Concentrations of ethane (C2H6) in the lower stratosphere and upper troposphere and acetylene (C2H2) in the upper troposphere deduced from Atmospheric Trace Molecule Spectroscopy/Spacelab 3 spectra

Science.gov (United States)

Rinsland, C. P.; Russell, J. M., III; Zander, R.; Farmer, C. B.; Norton, R. H.

1987-01-01

This paper reports the results of the spectroscopic analysis of C2H6 and C2H2 absorption spectra obtained by the Atmospheric Trace Molecule Spectroscopy (ATMOS) instrument flown on the Shuttle as part of the Spacelab 3 mission. The spectra were recorded during sunset occultations occurring between 25 deg N and 31 deg N latitudes, yielding volume-mixing ratio profiles of C2H6 in the lower stratosphere and the upper troposphere, and an upper tropospheric profile of C2H2. These results compare well with previous in situ and remote sounding data obtained at similar latitudes and with model calculations. The results demonstrate the feasibility of the ATMOS instrument to sound the lower atmosphere from space.

Humidification and secretion volume in mechanically ventilated patients.

Science.gov (United States)

Solomita, Mario; Palmer, Lucy B; Daroowalla, Feroza; Liu, Jeffrey; Miller, Dori; LeBlanc, Deniese S; Smaldone, Gerald C

2009-10-01

To determine potential effects of humidification on the volume of airway secretions in mechanically ventilated patients. Water vapor delivery from devices providing non-heated-wire humidification, heated-wire humidification, and heat and moisture exchanger (HME) were quantified on the bench. Then, patients requiring 24-hour mechanical ventilation were exposed sequentially to each of these humidification devices, and secretions were removed and measured by suctioning every hour during the last 4 hours of the 24-hour study period. In vitro water vapor delivery was greater using non-heated-wire humidification, compared to heated-wire humidification and HME. In vivo, a total of 9 patients were studied. Secretion volume following humidification by non-heated-wire humidification was significantly greater than for heated-wire humidification and HME (P=.004). The volume of secretions appeared to be linked to humidification, as greater water vapor delivery measured in vitro was associated with greater secretion volume in vivo.

Upper-tropospheric CO and O3 budget during the Asian summer monsoon

Directory of Open Access Journals (Sweden)

B. Barret

2016-07-01

Full Text Available During the Asian summer monsoon, the circulation in the upper troposphere/lower stratosphere (UTLS is dominated by the Asian monsoon anticyclone (AMA. Pollutants convectively uplifted to the upper troposphere are trapped within this anticyclonic circulation that extends from the Pacific Ocean to the Eastern Mediterranean basin. Among the uplifted pollutants are ozone (O3 and its precursors, such as carbon monoxide (CO and nitrogen oxides (NOx. Many studies based on global modeling and satellite data have documented the source regions and transport pathways of primary pollutants (CO, HCN into the AMA. Here, we aim to quantify the O3 budget by taking into consideration anthropogenic and natural sources. We first use CO and O3 data from the MetOp-A/IASI sensor to document their tropospheric distributions over Asia, taking advantage of the useful information they provide on the vertical dimension. These satellite data are used together with MOZAIC tropospheric profiles recorded in India to validate the distributions simulated by the global GEOS-Chem chemistry transport model. Over the Asian region, UTLS monthly CO and O3 distributions from IASI and GEOS-Chem display the same large-scale features. UTLS CO columns from GEOS-Chem are in agreement with IASI, with a low bias of 11 ± 9 % and a correlation coefficient of 0.70. For O3, the model underestimates IASI UTLS columns over Asia by 14 ± 26 % but the correlation between both is high (0.94. GEOS-Chem is further used to quantify the CO and O3 budget through sensitivity simulations. For CO, these simulations confirm that South Asian anthropogenic emissions have a more important impact on enhanced concentrations within the AMA (∼  25 ppbv than East Asian emissions (∼  10 ppbv. The correlation between enhanced emissions over the Indo-Gangetic Plain and monsoon deep convection is responsible for this larger impact. Consistently, South Asian anthropogenic NOx emissions also

Retrieval of global upper tropospheric and stratospheric formaldehyde (H2CO distributions from high-resolution MIPAS-Envisat spectra

Directory of Open Access Journals (Sweden)

G. P. Stiller

2008-02-01

Full Text Available The Fourier transform spectrometer MIPAS (Michelson Interferometer for Passive Atmospheric Sounding on Envisat measures infrared emission of the Earth's atmosphere in a limb viewing mode. High spectral resolution measurements of MIPAS are sensitive to formaldehyde from the upper troposphere to the stratopause. Single profile retrievals of formaldehyde are dominated by a 60% noise error; however zonal mean values for 30 days of data during 8 September 2003 and 1 December 2003 reduces this error by a factor of 20 or more. The number of degrees of freedom for single profile retrieval ranges from 2 to 4.5 depending on latitude and number of cloud-free tangent altitudes. In the upper tropical troposphere zonal mean values of about 70 parts per trillion by volume (pptv were found, which have been attributed to biomass burning emissions. In the stratosphere, formaldehyde values are determined by photochemical reactions. In the upper tropical stratosphere, formaldehyde zonal mean maximum values can reach 130 pptv. Diurnal variations in this region can be up to 50 pptv. Comparisons with other satellite instruments show generally good agreement in the region of upper troposphere and lower stratosphere as well as in the upper stratosphere.

First detection of ammonia (NH3 in the Asian summer monsoon upper troposphere

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M. Höpfner

2016-11-01

Full Text Available Ammonia (NH3 has been detected in the upper troposphere by the analysis of averaged MIPAS (Michelson Interferometer for Passive Atmospheric Sounding infrared limb-emission spectra. We have found enhanced amounts of NH3 within the region of the Asian summer monsoon at 12–15 km altitude. Three-monthly, 10° longitude  ×  10° latitude average profiles reaching maximum mixing ratios of around 30 pptv in this altitude range have been retrieved, with a vertical resolution of 3–8 km and estimated errors of about 5 pptv. These observations show that loss processes during transport from the boundary layer to the upper troposphere within the Asian monsoon do not deplete the air entirely of NH3. Thus, ammonia might contribute to the so-called Asian tropopause aerosol layer by the formation of ammonium aerosol particles. On a global scale, outside the monsoon area and during different seasons, we could not detect enhanced values of NH3 above the actual detection limit of about 3–5 pptv. This upper bound helps to constrain global model simulations.

Role of Aquaporin Water Channels in Airway Fluid Transport, Humidification, and Surface Liquid Hydration

Science.gov (United States)

Song, Yuanlin; Jayaraman, Sujatha; Yang, Baoxue; Matthay, Michael A.; Verkman, A.S.

2001-01-01

Several aquaporin-type water channels are expressed in mammalian airways and lung: AQP1 in microvascular endothelia, AQP3 in upper airway epithelia, AQP4 in upper and lower airway epithelia, and AQP5 in alveolar epithelia. Novel quantitative methods were developed to compare airway fluid transport–related functions in wild-type mice and knockout mice deficient in these aquaporins. Lower airway humidification, measured from the moisture content of expired air during mechanical ventilation with dry air through a tracheotomy, was 54–56% efficient in wild-type mice, and reduced by only 3–4% in AQP1/AQP5 or AQP3/AQP4 double knockout mice. Upper airway humidification, measured from the moisture gained by dry air passed through the upper airways in mice breathing through a tracheotomy, decreased from 91 to 50% with increasing ventilation from 20 to 220 ml/min, and reduced by 3–5% in AQP3/AQP4 knockout mice. The depth and salt concentration of the airway surface liquid in trachea was measured in vivo using fluorescent probes and confocal and ratio imaging microscopy. Airway surface liquid depth was 45 ± 5 μm and [Na+] was 115 ± 4 mM in wild-type mice, and not significantly different in AQP3/AQP4 knockout mice. Osmotic water permeability in upper airways, measured by an in vivo instillation/sample method, was reduced by ∼40% by AQP3/AQP4 deletion. In doing these measurements, we discovered a novel amiloride-sensitive isosmolar fluid absorption process in upper airways (13% in 5 min) that was not affected by aquaporin deletion. These results establish the fluid transporting properties of mouse airways, and indicate that aquaporins play at most a minor role in airway humidification, ASL hydration, and isosmolar fluid absorption. PMID:11382807

Evaluation of Satellite-Based Upper Troposphere Cloud Top Height Retrievals in Multilayer Cloud Conditions During TC4

Science.gov (United States)

Chang, Fu-Lung; Minnis, Patrick; Ayers, J. Kirk; McGill, Matthew J.; Palikonda, Rabindra; Spangenberg, Douglas A.; Smith, William L., Jr.; Yost, Christopher R.

2010-01-01

Upper troposphere cloud top heights (CTHs), restricted to cloud top pressures (CTPs) less than 500 hPa, inferred using four satellite retrieval methods applied to Twelfth Geostationary Operational Environmental Satellite (GOES-12) data are evaluated using measurements during the July August 2007 Tropical Composition, Cloud and Climate Coupling Experiment (TC4). The four methods are the single-layer CO2-absorption technique (SCO2AT), a modified CO2-absorption technique (MCO2AT) developed for improving both single-layered and multilayered cloud retrievals, a standard version of the Visible Infrared Solar-infrared Split-window Technique (old VISST), and a new version of VISST (new VISST) recently developed to improve cloud property retrievals. They are evaluated by comparing with ER-2 aircraft-based Cloud Physics Lidar (CPL) data taken during 9 days having extensive upper troposphere cirrus, anvil, and convective clouds. Compared to the 89% coverage by upper tropospheric clouds detected by the CPL, the SCO2AT, MCO2AT, old VISST, and new VISST retrieved CTPs less than 500 hPa in 76, 76, 69, and 74% of the matched pixels, respectively. Most of the differences are due to subvisible and optically thin cirrus clouds occurring near the tropopause that were detected only by the CPL. The mean upper tropospheric CTHs for the 9 days are 14.2 (+/- 2.1) km from the CPL and 10.7 (+/- 2.1), 12.1 (+/- 1.6), 9.7 (+/- 2.9), and 11.4 (+/- 2.8) km from the SCO2AT, MCO2AT, old VISST, and new VISST, respectively. Compared to the CPL, the MCO2AT CTHs had the smallest mean biases for semitransparent high clouds in both single-layered and multilayered situations whereas the new VISST CTHs had the smallest mean biases when upper clouds were opaque and optically thick. The biases for all techniques increased with increasing numbers of cloud layers. The transparency of the upper layer clouds tends to increase with the numbers of cloud layers.

Hydrogen Cyanide in the Upper Troposphere: GEM-AQ Simulation and Comparison with ACE-FTS Observations

Science.gov (United States)

Lupu, A.; Kaminski, J. W.; Neary, L.; McConnell, J. C.; Toyota, K.; Rinsland, C. P.; Bernath, P. F.; Walker, K. A.; Boone, C. D.; Nagahama, Y.;

A comparison of lightning and aircraft sources of NO{sub x} in the upper troposphere

Energy Technology Data Exchange (ETDEWEB)

Penner, J E; Walton, J J [Michigan Univ., Ann Arbor, MI (United States). Dept. of Atmospheric, Oceanic and Space Physics; Bergmann, D J; Kinnison, D; Rotman, D [Lawrence Livermore National Lab., CA (United States). Atmospheric Science Div.; Price, C [Tel Aviv Univ. (Israel). Dept. of Geophysics and Planetary Sciences; Prather, M J [California Univ., Irvine, CA (United States). Dept. of Earth System Science; Pickering, K E [Maryland Univ., College Park, MD (United States). Dept. of Meteorology; Baughcum, S L [Boeing Commerial Airplane Group, Seatlle, WA (United States)

1998-12-31

Uncertainties in the assessment of the contribution of aircraft to upper tropospheric NO{sub x} arise from uncertainties in model treatment of transport, uncertainties in source strengths, and uncertainties in chemical rates and reactions determining the partitioning between NO{sub x} and NO{sub y}. Two different chemical transport models are used to examine the range of uncertainty in the contribution of aircraft to upper tropospheric NO{sub x} from model representations of transport. Uncertainties caused by uncertainties in the rate of production of NO{sub x} from lightning and uncertainties from the range of background concentrations of HNO{sub 3} are also examined. Uncertainties in the treatment of vertical transport and uncertainties in the source strength from lightning contribute to a large range in model results for background NO{sub x}. (author) 18 refs.

A comparison of lightning and aircraft sources of NO{sub x} in the upper troposphere

Energy Technology Data Exchange (ETDEWEB)

Penner, J.E.; Walton, J.J. [Michigan Univ., Ann Arbor, MI (United States). Dept. of Atmospheric, Oceanic and Space Physics; Bergmann, D.J.; Kinnison, D.; Rotman, D. [Lawrence Livermore National Lab., CA (United States). Atmospheric Science Div.; Price, C. [Tel Aviv Univ. (Israel). Dept. of Geophysics and Planetary Sciences; Prather, M.J. [California Univ., Irvine, CA (United States). Dept. of Earth System Science; Pickering, K.E. [Maryland Univ., College Park, MD (United States). Dept. of Meteorology; Baughcum, S.L. [Boeing Commerial Airplane Group, Seatlle, WA (United States)

1997-12-31

Uncertainties in the assessment of the contribution of aircraft to upper tropospheric NO{sub x} arise from uncertainties in model treatment of transport, uncertainties in source strengths, and uncertainties in chemical rates and reactions determining the partitioning between NO{sub x} and NO{sub y}. Two different chemical transport models are used to examine the range of uncertainty in the contribution of aircraft to upper tropospheric NO{sub x} from model representations of transport. Uncertainties caused by uncertainties in the rate of production of NO{sub x} from lightning and uncertainties from the range of background concentrations of HNO{sub 3} are also examined. Uncertainties in the treatment of vertical transport and uncertainties in the source strength from lightning contribute to a large range in model results for background NO{sub x}. (author) 18 refs.

The Ozone Budget in the Upper Troposphere from Global Modeling Initiative (GMI)Simulations

Science.gov (United States)

Rodriquez, J.; Duncan, Bryan N.; Logan, Jennifer A.

2006-01-01

Ozone concentrations in the upper troposphere are influenced by in-situ production, long-range tropospheric transport, and influx of stratospheric ozone, as well as by photochemical removal. Since ozone is an important greenhouse gas in this region, it is particularly important to understand how it will respond to changes in anthropogenic emissions and changes in stratospheric ozone fluxes.. This response will be determined by the relative balance of the different production, loss and transport processes. Ozone concentrations calculated by models will differ depending on the adopted meteorological fields, their chemical scheme, anthropogenic emissions, and treatment of the stratospheric influx. We performed simulations using the chemical-transport model from the Global Modeling Initiative (GMI) with meteorological fields from (It)h e NASA Goddard Institute for Space Studies (GISS) general circulation model (GCM), (2) the atmospheric GCM from NASA's Global Modeling and Assimilation Office(GMAO), and (3) assimilated winds from GMAO . These simulations adopt the same chemical mechanism and emissions, and adopt the Synthetic Ozone (SYNOZ) approach for treating the influx of stratospheric ozone -. In addition, we also performed simulations for a coupled troposphere-stratosphere model with a subset of the same winds. Simulations were done for both 4degx5deg and 2degx2.5deg resolution. Model results are being tested through comparison with a suite of atmospheric observations. In this presentation, we diagnose the ozone budget in the upper troposphere utilizing the suite of GMI simulations, to address the sensitivity of this budget to: a) the different meteorological fields used; b) the adoption of the SYNOZ boundary condition versus inclusion of a full stratosphere; c) model horizontal resolution. Model results are compared to observations to determine biases in particular simulations; by examining these comparisons in conjunction with the derived budgets, we may pinpoint

Under-humidification and over-humidification during moderate induced hypothermia with usual devices.

Science.gov (United States)

Lellouche, François; Qader, Siham; Taille, Solenne; Lyazidi, Aissam; Brochard, Laurent

2006-07-01

In mechanically ventilated patients with induced hypothermia, the efficacy of heat and moisture exchangers and heated humidifiers to adequately humidify the airway is poorly known. The aim of the study was to assess the efficacy of different humidification devices during moderate hypothermia. Prospective, cross-over randomized study. Medical Intensive Care Unit in a University Hospital. Nine adult patients hospitalized after cardiac arrest in whom moderate hypothermia was induced (33 degrees C for 24[Symbol: see text]h). Patients were ventilated at admission (period designated "normothermia") with a heat and moisture exchanger, and were randomly ventilated during hypothermia with a heat and moisture exchanger, a heated humidifier, and an active heat and moisture exchanger. Core temperature, inspired and expired gas absolute and relative humidity were measured. Each system demonstrated limitations in its ability to humidify gases in the specific situation of hypothermia. Performances of heat and moisture exchangers were closely correlated to core temperature (r (2)[Symbol: see text]=[Symbol: see text]0.84). During hypothermia, heat and moisture exchangers led to major under-humidification, with absolute humidity below 25[Symbol: see text]mgH(2)O/l. The active heat and moisture exchanger slightly improved humidification. Heated humidifiers were mostly adequate but led to over-humidification in some patients, with inspiratory absolute humidity higher than maximal water content at 33 degrees C with a positive balance between inspiratory and expiratory water content. These results suggest that in the case of moderate hypothermia, heat and moisture exchangers should be used cautiously and that heated humidifiers may lead to over-humidification with the currently recommended settings.

Upper Troposphere Lower Stratosphere structure during convective systems using GPS radio occultations

DEFF Research Database (Denmark)

Biondi, Riccardo

The deep convective systems play a fundamental role in atmospheric circulation and climate. Thunderstorms and meso-scale convective systems produce fast vertical transport, redistributing water vapor and trace gases and influencing the thermal structure of the upper troposphere and lower...... stratosphere (UTLS) contributing to the troposphere-stratosphere transport and affecting the Earth global circulation and the climate changes. The Global Positioning System (GPS) Radio Occultation (RO) technique enables measurement of atmospheric density structure in any meteorological condition...... to the analysis of tropical storms for the future mission ACES will also be evaluated. Using data from the past and ongoing GPS RO missions we have defined an algorithm to detect the clouds top of the convective systems and their thermal structure. Other satellite and in-situ measurements co-located with GPS ROs...

Satellite observations and modeling of transport in the upper troposphere through the lower mesosphere during the 2006 major stratospheric sudden warming

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W. H. Daffer

2009-07-01

Full Text Available An unusually strong and prolonged stratospheric sudden warming (SSW in January 2006 was the first major SSW for which globally distributed long-lived trace gas data are available covering the upper troposphere through the lower mesosphere. We use Aura Microwave Limb Sounder (MLS, Atmospheric Chemistry Experiment-Fourier Transform Spectrometer (ACE-FTS data, the SLIMCAT Chemistry Transport Model (CTM, and assimilated meteorological analyses to provide a comprehensive picture of transport during this event. The upper tropospheric ridge that triggered the SSW was associated with an elevated tropopause and layering in trace gas profiles in conjunction with stratospheric and tropospheric intrusions. Anomalous poleward transport (with corresponding quasi-isentropic troposphere-to-stratosphere exchange at the lowest levels studied in the region over the ridge extended well into the lower stratosphere. In the middle and upper stratosphere, the breakdown of the polar vortex transport barrier was seen in a signature of rapid, widespread mixing in trace gases, including CO, H₂O, CH₄ and N₂O. The vortex broke down slightly later and more slowly in the lower than in the middle stratosphere. In the middle and lower stratosphere, small remnants with trace gas values characteristic of the pre-SSW vortex lingered through the weak and slow recovery of the vortex. The upper stratospheric vortex quickly reformed, and, as enhanced diabatic descent set in, CO descended into this strong vortex, echoing the fall vortex development. Trace gas evolution in the SLIMCAT CTM agrees well with that in the satellite trace gas data from the upper troposphere through the middle stratosphere. In the upper stratosphere and lower mesosphere, the SLIMCAT simulation does not capture the strong descent of mesospheric CO and H₂O values into the reformed vortex; this poor CTM performance in the upper stratosphere and lower mesosphere results

Hydrogen Radicals, Nitrogen Radicals, and the Production of Ozone in the Middle and Upper Troposphere

Science.gov (United States)

Bui, T. P.

1997-01-01

The concentrations of hydrogen radicals, OH and HO2, in the middle and upper troposphere were measured simultaneously with those of NO, O3,CO, H20, CH4, non-methane hydrocarbons, and with the ultraviolet and visible radiation field.

Y-piece temperature and humidification during mechanical ventilation.

Science.gov (United States)

Solomita, Mario; Daroowalla, Feroza; Leblanc, Deniese S; Smaldone, Gerald C

2009-04-01

Practitioners often presume there is adequate humidification in the ventilator circuit if the Y-piece is at a specified temperature, but control of Y-piece temperature may be inadequate to ensure adequate humidification. In an in vitro bench model we measured water-vapor delivery with several heated humidification setups and a wide range of minute volume (V (E)) values. The setup included a condenser, hygrometry, and thermometer. First, we calibrated the system with a point-source humidifier and water pump. Then we tested the water-vapor delivery during non-heated-wire humidification and during heated-wire humidification with a temperature gradient of +3 degrees C, 0 degrees C, and -3 degrees C between the humidifier and the Y-piece. We compared the results to 2 recommended humidification values: 100% saturated (absolute humidity 44 mg H(2)O/L) gas at 37 degrees C (saturated/37 degrees C); and 75% saturated (absolute humidity 33 mg H(2)O/L), which is the humidity recommended by the International Organization for Standardization (the ISO standard). In all the experiments the setup was set to provide 35 degrees C at the Y-piece. Our method for measuring water-vapor delivery closely approximated the amount delivered by a calibrated pump, but slightly underestimated the water-vapor delivery in all the experiments and the whole V (E) range. At all V (E) values, water-vapor delivery during non-heated-wire humidification matched or exceeded saturated/37 degrees C and was significantly greater than that during heated-wire humidification. During heated-wire humidification, water-vapor delivery varied with the temperature gradient and did not reach saturated/37 degrees C at V (E) > 6 L/min. Water-vapor delivery with the negative temperature gradient was below the ISO standard. Maintaining temperature at one point in the inspiratory circuit (eg, Y-piece), does not ensure adequate water-vapor delivery. Other factors (humidification system, V (E), gradient setting) are critical

Nasal high-frequency oscillatory ventilation impairs heated humidification: A neonatal bench study.

Science.gov (United States)

Ullrich, Tim L; Czernik, Christoph; Bührer, Christoph; Schmalisch, Gerd; Fischer, Hendrik S

2017-11-01

Nasal high-frequency oscillatory ventilation (nHFOV) is a novel mode of non-invasive ventilation used in neonates. However, upper airway obstructions due to viscous secretions have been described as specific adverse effects. We hypothesized that high-frequency oscillations reduce air humidity in the oropharynx, resulting in upper airway desiccation. Therefore, we aimed to investigate the effects of nHFOV ventilatory settings on oropharyngeal gas conditions. NHFOV or nasal continuous positive airway pressure (nCPAP) was applied, along with heated humidification, to a previously established neonatal bench model that simulates oropharyngeal gas conditions during spontaneous breathing through an open mouth. A digital thermo-hygro sensor measured oropharyngeal temperature (T) and humidity at various nHFOV frequencies (7, 10, 13 Hz), amplitudes (10, 20, 30 cmH 2 O), and inspiratory-to-expiratory (I:E) ratios (25:75, 33:66, 50:50), and also during nCPAP. Relative humidity was always >99%, but nHFOV resulted in lower mean T and absolute humidity (AH) in comparison to nCPAP (P humidification during nHFOV. © 2017 Wiley Periodicals, Inc.

Summertime mid-to-upper tropospheric nitrous oxide over the Mediterranean as a footprint of Indian emissions

Science.gov (United States)

Kangah, Yannick; Ricaud, Philippe; Attié, Jean-Luc; Saitoh, Naoko; Hauglustaine, Didier; El Amraoui, Laaziz; Zbinden, Regina; Delon, Claire

2016-04-01

We used global scale thermal infrared measurements of mid-to-upper tropospheric nitrous oxide (N2O) from the Greenhouse gases Observing SATellite (GOSAT) and outputs from the 3D Chemical Transport Model LMDz-OR-INCA to assess the impact of the Indian subcontinent N2O emissions on the N2O field over the eastern Mediterranean Basin (MB) during summer. The use of nitrogen fertilizer coupled with high soil humidity during summer monsoon period produce high emissions of N2O in many south Asian countries and especially the Indian subcontinent. N2O is transported to the upper troposphere by updrafts associated to the monsoon and redistributed westward to the eastern Mediterranean via the Asian Monsoon Anticyclone. This summertime (June-July-August) enrichment in N2O in the eastern Mediterranean produces a maximum in the east-west difference of MB mid-to-upper tropospheric N2O anomaly representative for the period 2010-2013 with a maximum in July and a peak-to-peak amplitude of ~1.0 ± 0.3 ppbv observed by GOSAT consistently with LMDz-OR-INCA but less intense (~0.5 ppbv). This summertime enrichment of N2O over the eastern Mediterranean is consistent with the increase of the surface emissions and the convective precipitations over the Indian subcontinent during the summer monsoon period. N2O over the eastern Mediterranean can therefore be considered as a footprint of Indian summertime emissions.

Artificial humidification for the mechanically ventilated patient.

Science.gov (United States)

Selvaraj, N

Caring for patients who are mechanically ventilated poses many challenges for critical care nurses. It is important to humidify the patient's airways artificially to prevent complications such as ventilator-associated pneumonia. There is no gold standard to determine which type of humidification is best for patients who are artificially ventilated. This article provides an overview of commonly used artificial humidification for mechanically ventilated patients and discusses nurses' responsibilities in caring for patients receiving artificial humidification.

Influence of isentropic transport on seasonal ozone variations in the lower stratosphere and subtropical upper troposphere

Science.gov (United States)

Jing, P.; Cunnold, D. M.; Yang, E.-S.; Wang, H.-J.

2005-01-01

The isentropic cross-tropopause ozone transport has been estimated in both hemispheres in 1999 based on the potential vorticity mapping of Stratospheric Aerosol and Gas Experiment 11 ozone measurements and contour advection calculations using the NASA Goddard Space Flight Center Global and Modeling Assimilation Office analysis. The estimated net isentropic stratosphere-to-troposphere ozone flux is approx.118 +/- 61 x 10(exp9)kg/yr globally within the layer between 330 and 370 K in 1999; 60% of it is found in the Northern Hemisphere, and 40% is found in the Southern Hemisphere. The monthly average ozone fluxes are strongest in summer and weakest in winter in both hemispheres. The seasonal variations of ozone in the lower stratosphere (LS) and upper troposphere (UT) have been analyzed using ozonesonde observations from ozonesonde stations in the extratropics and subtropics, respectively. It is shown that observed ozone levels increase in the UT over subtropical ozonesonde stations and decrease in the LS over extratropical stations in late spring/early summer and that the ozone increases in the summertime subtropical UT are unlikely to be explained by photochemical ozone production and diabatic transport alone. We conclude that isentropic transport is a significant contributor to ozone levels in the subtropical upper troposphere, especially in summer.

The Origins of Air Parcels Uplifted in a Two Dimensional Gravity Wave in the Tropical Upper Troposphere During the NASA Stratosphere Troposphere Exchange Project (STEP)

Science.gov (United States)

Selkirk, Henry B.; Pfister, Leonhard; Chan, K. Roland; Kritz, Mark; Kelly, Ken

1989-01-01

During January and February 1987, as part of the Stratosphere-Troposphere Exchange Project, the NASA ER-2 made 11 flights from Darwin, Australia to investigate dehydration mechanisms in the vicinity of the tropical tropopause. After the monsoon onset in the second week of January, steady easterly flow of 15-25 ms (exp -1) was established in the upper troposphere and lower stratosphere over northern Australia and adjacent seas. Penetrating into this regime were elements of the monsoon convection such as overshooting convective turrets and extensive anvils including cyclone cloud shields. In cases of the latter, the resulting flow obstructions tended to produce mesoscale gravity waves. In several instances the ER- 2 meteorological and trace constituent measurements provide a detailed description of the structure of these gravity waves. Among these was STEP Flight 6, 22-23 January. It is of particular interest to STEP because of the close proximity of ice-laden and dehydrated air on the same isentropic surfaces. Convective events inject large amounts of ice into the upper troposphere and lower stratosphere which may not be completely removed by local precipitation processes. In the present instance, a gravity wave for removed from the source region appears to induce relativity rapid upward motion in the ice-laden air and subsequent dessication. Potential mechanisms for such a localized removal process are under investigation.

Humidification during invasive and noninvasive mechanical ventilation: 2012.

Science.gov (United States)

Restrepo, Ruben D; Walsh, Brian K

2012-05-01

We searched the MEDLINE, CINAHL, and Cochrane Library databases for articles published between January 1990 and December 2011. The update of this clinical practice guideline is based on 184 clinical trials and systematic reviews, and 10 articles investigating humidification during invasive and noninvasive mechanical ventilation. The following recommendations are made following the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) scoring system: 1. Humidification is recommended on every patient receiving invasive mechanical ventilation. 2. Active humidification is suggested for noninvasive mechanical ventilation, as it may improve adherence and comfort. 3. When providing active humidification to patients who are invasively ventilated, it is suggested that the device provide a humidity level between 33 mg H(2)O/L and 44 mg H(2)O/L and gas temperature between 34°C and 41°C at the circuit Y-piece, with a relative humidity of 100%. 4. When providing passive humidification to patients undergoing invasive mechanical ventilation, it is suggested that the HME provide a minimum of 30 mg H(2)O/L. 5. Passive humidification is not recommended for noninvasive mechanical ventilation. 6. When providing humidification to patients with low tidal volumes, such as when lung-protective ventilation strategies are used, HMEs are not recommended because they contribute additional dead space, which can increase the ventilation requirement and P(aCO(2)). 7. It is suggested that HMEs are not used as a prevention strategy for ventilator-associated pneumonia.

Towards a Model Climatology of Relative Humidity in the Upper Troposphere for Estimation of Contrail and Contrail-Induced Cirrus

Science.gov (United States)

Selkirk, Henry B.; Manyin, M.; Ott, L.; Oman, L.; Benson, C.; Pawson, S.; Douglass, A. R.; Stolarski, R. S.

2011-01-01

The formation of contrails and contrail cirrus is very sensitive to the relative humidity of the upper troposphere. To reduce uncertainty in an estimate of the radiative impact of aviation-induced cirrus, a model must therefore be able to reproduce the observed background moisture fields with reasonable and quantifiable fidelity. Here we present an upper tropospheric moisture climatology from a 26-year ensemble of simulations using the GEOS CCM. We compare this free-running model's moisture fields to those obtained from the MLS and AIRS satellite instruments, our most comprehensive observational databases for upper tropospheric water vapor. Published comparisons have shown a substantial wet bias in GEOS-5 assimilated fields with respect to MLS water vapor and ice water content. This tendency is clear as well in the GEOS CCM simulations. The GEOS-5 moist physics in the GEOS CCM uses a saturation adjustment that prevents supersaturation, which is unrealistic when compared to in situ moisture observations from MOZAIC aircraft and balloon sondes as we will show. Further, the large-scale satellite datasets also consistently underestimate super-saturation when compared to the in-situ observations. We place these results in the context of estimates of contrail and contrail cirrus frequency.

Commentary on using equivalent latitude in the upper troposphere and lower stratosphere

Directory of Open Access Journals (Sweden)

L. L. Pan

2012-10-01

Full Text Available We discuss the use of potential vorticity (PV based equivalent latitude (EqLat and potential temperature (θ coordinates in the upper troposphere and lower stratosphere (UTLS for chemical transport studies. The main objective is to provide a cautionary note on using EqLat-θ coordinates for aggregating chemical tracers in the UTLS. Several examples are used to show 3-D distributions of EqLat together with chemical constituents for a range of θ. We show that the use of PV-θ coordinates may not be suitable for several reasons when tropospheric processes are an important part of a study. Due to the different static stability structures between the stratosphere and troposphere, the use of θ as a vertical coordinate does not provide equal representations of the UT and LS. Since the θ surfaces in the troposphere often intersect the surface of the Earth, the θ variable does not work well distinguishing the UT from the boundary layer when used globally as a vertical coordinate. We further discuss the duality of PV/EqLat as a tracer versus as a coordinate variable. Using an example, we show that while PV/EqLat serves well as a transport tracer in the UTLS region, it may conceal the chemical structure associated with wave breaking when used as a coordinate to average chemical tracers. Overall, when choosing these coordinates, considerations need to be made not only based on the time scale of PV being a conservative tracer, but also the specific research questions to be addressed.

Evaluating Lightning-generated NOx (LNOx) Parameterization based on Cloud Top Height at Resolutions with Partially-resolved Convection for Upper Tropospheric Chemistry Studies

Science.gov (United States)

Wong, J.; Barth, M. C.; Noone, D. C.

2012-12-01

Lightning-generated nitrogen oxides (LNOx) is an important precursor to tropospheric ozone production. With a meteorological time-scale variability similar to that of the ozone chemical lifetime, it can nonlinearly perturb tropospheric ozone concentration. Coupled with upper-air circulation patterns, LNOx can accumulate in significant amount in the upper troposphere with other precursors, thus enhancing ozone production (see attached figure). While LNOx emission has been included and tuned extensively in global climate models, its inclusions in regional chemistry models are seldom tested. Here we present a study that evaluates the frequently used Price and Rind parameterization based on cloud-top height at resolutions that partially resolve deep convection using the Weather Research and Forecasting model with Chemistry (WRF-Chem) over the contiguous United States. With minor modifications, the parameterization is shown to generate integrated flash counts close to those observed. However, the modeled frequency distribution of cloud-to-ground flashes do not represent well for storms with high flash rates, bringing into question the applicability of the intra-cloud/ground partitioning (IC:CG) formulation of Price and Rind in some studies. Resolution dependency also requires attention when sub-grid cloud-tops are used instead of the originally intended grid-averaged cloud-top. LNOx passive tracers being gathered by monsoonal upper tropospheric anticyclone.

Distribution of tropical tropospheric water vapor

Science.gov (United States)

Sun, De-Zheng; Lindzen, Richard S.

1993-01-01

Utilizing a conceptual model for tropical convection and observational data for water vapor, the maintenance of the vertical distribution of the tropical tropospheric water vapor is discussed. While deep convection induces large-scale subsidence that constrains the turbulent downgradient mixing to within the convective boundary layer and effectively dries the troposphere through downward advection, it also pumps hydrometeors into the upper troposphere, whose subsequent evaporation appears to be the major source of moisture for the large-scale subsiding motion. The development of upper-level clouds and precipitation from these clouds may also act to dry the outflow, thus explaining the low relative humidity near the tropopause. A one-dimensional model is developed to simulate the mean vertical structure of water vapor in the tropical troposphere. It is also shown that the horizontal variation of water vapor in the tropical troposphere above the trade-wind boundary layer can be explained by the variation of a moisture source that is proportional to the amount of upper-level clouds. Implications for the nature of water vapor feedback in global warming are discussed.

[Airway humidification practices in Chilean intensive care units].

Science.gov (United States)

Retamal, Jaime; Castillo, Juan; Bugedo, Guillermo; Bruhn, Alejandro

2012-11-01

In patients with an artificial airway, inspired gases can be humidified and heated using a passive (heat and moisture exchange filter - HMEF), or an active system (heated humidifier). To assess how humidification is carried out and what is the usual clinical practice in this field in Chilean intensive care units (ICUs). A specific survey to evaluate humidification system features as well as caregivers' preferences regarding humidification systems, was carried out on the same day in all Chilean ICUs. Fifty-five ICUs were contacted and 44 of them completed the survey. From a total of 367 patients, 254 (69%) required humidification because they were breathing through an artificial airway. A heated humidifier was employed only in 12 patients (5%). Forty-three ICUs (98%) used HMEF as their routine humidification system. In 52% of surveyed ICUs, heated humidifiers were not available. In Chile the main method to humidify and heat inspired gases in patients with an artificial airway is the HMEF. Although there are clear indications for the use of heated humidifiers, they are seldom employed.

A large impact of tropical biomass burning on CO and CO{sub 2} in the upper troposphere

Energy Technology Data Exchange (ETDEWEB)

Hidekazu Matsueda; Shoichi Taguchi; Hisayuki Y; Inoue & Masao Ishii [Meteorological Research Institute, Tsukuba-shi (Japan). Geochemical Research Department

2002-07-01

A large interannual variation of biomass burning emissions from Southeast Asia is associated with the ENSO events. During 1997/98 and 1994 El Nino years, uncontrolled wildfires of tropical rainforests and peat lands in Indonesia were enlarged due to a long drought. Enhanced CO injection into the upper troposphere from the intense Indonesian fires was clearly observed in the 8-year measurements from a regular flask sampling over the western Pacific using a JAL airliner between Australia and Japan. This airliner observation also revealed that upper tropospheric CO{sub 2} cycle largely changed during the 1997 El Nio year due partly to the biomass burning emissions. Widespread pollution from the biomass burnings in Southeast Asia was simulated using a CO tracer driven by a 3D global chemical transport model. This simulation indicates that tropical deep convections connected to rapid advection by the subtropical jet play a significant role in dispersing biomass-burning emissions from Southeast Asia on a global scale.

Generation of layering in the upper arctic troposphere away from the jet stream

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A. Karpetchko

Full Text Available Ozone sounding databases for two stations, So-dankylä (67° N, 27° E and Ny-Ålesund (79° N, 12° E were used in order to investigate the generation of layering in the upper and middle troposphere of the Arctic. We concentrated on dry, ozone-rich and stable layers observed below the thermal tropopause under light wind conditions. This condition ensures that the observed layer is not a tropopause fold, a well-known phenomenon that develops within frontal zones near the jet stream. Selection criteria for ozone, humidity and stability anomalies of the tropopause fold detection algorithm were used here to pick out for detailed studies the most pronounced examples of laminae. For all these cases the meteorological situations were investigated in order to establish the origin of the observed layers. We found that layers could be classified into two groups. Laminae of the first group were observed equatorward of the jet stream and those of a second group were observed poleward of the jet. The meteorological situation for the first group resembles that for equatorward stratospheric streamer propagation. It was found that this group accounts for only a small fraction of the layers observed at Sodankylä and for none of those observed at Ny-Ålesund during the period investigated. A large case-to-case variability in the synoptic situation was observed for the second group of laminae, which were detected northward of the jet stream. Nevertheless, in about half of the cases, streamers of tropospheric air were found in the vicinity of the stations on the isentropic surfaces just above the detected stratospheric layers. Back trajectory analyses showed that these layers originated in the vicinity of the polar jet stream. We suppose that laminae-like structures in the troposphere were caused, in both groups, by equatorward (poleward advection of the stratospheric (tropospheric air, together with differential vertical shear. Forward-trajectory calculations

Generation of layering in the upper arctic troposphere away from the jet stream

Directory of Open Access Journals (Sweden)

A. Karpetchko

2003-07-01

Full Text Available Ozone sounding databases for two stations, So-dankylä (67° N, 27° E and Ny-Ålesund (79° N, 12° E were used in order to investigate the generation of layering in the upper and middle troposphere of the Arctic. We concentrated on dry, ozone-rich and stable layers observed below the thermal tropopause under light wind conditions. This condition ensures that the observed layer is not a tropopause fold, a well-known phenomenon that develops within frontal zones near the jet stream. Selection criteria for ozone, humidity and stability anomalies of the tropopause fold detection algorithm were used here to pick out for detailed studies the most pronounced examples of laminae. For all these cases the meteorological situations were investigated in order to establish the origin of the observed layers. We found that layers could be classified into two groups. Laminae of the first group were observed equatorward of the jet stream and those of a second group were observed poleward of the jet. The meteorological situation for the first group resembles that for equatorward stratospheric streamer propagation. It was found that this group accounts for only a small fraction of the layers observed at Sodankylä and for none of those observed at Ny-Ålesund during the period investigated. A large case-to-case variability in the synoptic situation was observed for the second group of laminae, which were detected northward of the jet stream. Nevertheless, in about half of the cases, streamers of tropospheric air were found in the vicinity of the stations on the isentropic surfaces just above the detected stratospheric layers. Back trajectory analyses showed that these layers originated in the vicinity of the polar jet stream. We suppose that laminae-like structures in the troposphere were caused, in both groups, by equatorward (poleward advection of the stratospheric (tropospheric air, together with differential vertical shear. Forward-trajectory calculations

Desiccant wheels for air humidification: An experimental and numerical analysis

International Nuclear Information System (INIS)

De Antonellis, Stefano; Intini, Manuel; Joppolo, Cesare Maria; Molinaroli, Luca; Romano, Francesco

2015-01-01

Highlights: • The use of desiccant wheel to humidify an air stream is investigated. • Air humidification is obtained by extracting water vapour from outdoor air. • Experimental tests in winter humidification conditions are performed. • The design of the proposed humidification system is numerically analyzed. • Effects of boundary conditions on humidification capacity are investigated. - Abstract: In this work the use of a desiccant wheel for air humidification is investigated through a numerical and experimental approach. In the proposed humidification system, water vapour is adsorbed from outdoor environment and it is released directly to the air stream supplied to the building. Such a system can be an interesting alternative to steam humidifiers in hospitals or, more generally, in applications where air contamination is a critical issue and therefore adiabatic humidifiers are not allowed. Performance of the proposed system is deeply investigated and optimal values of desiccant wheel configuration parameters are discussed. It is shown that in the investigated conditions, which are representative of Southern Europe winter climate, the system can properly match the latent load of the building. Finally, power consumption referred to the primary source of the proposed humidification system is compared to the one of steam humidifiers. The present analysis is carried out through experimental tests of a desiccant wheel in winter humidification conditions and through a phenomenological model of the device, based on heat and mass transfer equations.

Domiciliary humidification improves lung mucociliary clearance in patients with bronchiectasis.

Science.gov (United States)

Hasani, A; Chapman, T H; McCool, D; Smith, R E; Dilworth, J P; Agnew, J E

2008-01-01

Inspired air humidification has been reported to show some benefit in bronchiectatic patients. We have investigated the possibility that one effect might be to enhance mucociliary clearance. Such enhancement might, if it occurs, help to lessen the risks of recurrent infective episodes. Using a radioaerosol technique, we measured lung mucociliary clearance before and after 7 days of domiciliary humidification. Patients inhaled high flow saturated air at 37 degrees C via a patient-operated humidification nasal inhalation system for 3 h per day. We assessed tracheobronchial mucociliary clearance from the retention of (99m)Tc-labelled polystyrene tracer particles monitored for 6 h, with a follow-up 24-h reading. Ten out of 14 initially recruited patients (age 37-75 years; seven females) completed the study (two withdrew after their initial screening and two prior to the initial clearance test). Seven patients studied were non-smokers; three were ex-smokers (1-9 pack-years). Initial tracer radioaerosol distribution was closely similar between pre- and post-treatment. Following humidification, lung mucociliary clearance significantly improved, the area under the tracheobronchial retention curve decreased from 319 +/- 50 to 271 +/- 46%h (p humidification treatment improved lung mucociliary clearance in our bronchiectatic patients. Given this finding plus increasing laboratory and clinical interest in humidification mechanisms and effects, we believe further clinical trials of humidification therapy are desirable, coupled with analysis of humidification effects on mucus properties and transport.

Influence of humidification on comfort during noninvasive ventilation with a helmet.

Science.gov (United States)

Ueta, Kazuyoshi; Tomita, Toshiji; Uchiyama, Akinori; Ohta, Noriyuki; Iguchi, Naoya; Goto, Yukiko; Fujino, Yuji

2013-05-01

To evaluate optimal humidifier water temperature when using a helmet for noninvasive ventilation. Twenty-eight healthy individuals underwent 8 cm H2O CPAP ventilation with FIO2 of 0.21 and 0.5. Each was sequentially tested in the following order: using the helmet without humidification at ambient temperature; with humidification with unheated chamber water; and with humidification with the chamber water at 31°C, 34°C, and 37°C. At each setting, after a 20 min stabilization period, measurements were taken. Comfort level at each setting was evaluated using a visual analog scale rated zero (least comfortable) to 10 (most comfortable). Temperature and relative and absolute humidity inside the helmet increased; however, the comfort scores significantly decreased as the humidification chamber water temperature increased. Regardless of the FIO2, statistically significantly highest comfort scores were obtained when humidification water, with and without active humidification, was at ambient temperature. Unacceptable absolute humidity was obtained only without humidification at room temperature when FIO2 was 0.5. With the clinical use of a helmet, for patient comfort and mucosal humidification during CPAP, the most desirable conditions are likely to be obtained by humidifying without heating, that is by leaving the water in the humidifier chamber at room temperature.

Nitric acid particles in cold thick ice clouds observed at global scale: Link with lightning, temperature, and upper tropospheric water vapor

Science.gov (United States)

Chepfer, H.; Minnis, P.; Dubuisson, P.; Chiriaco, M.; Sun-Mack, S.; RivièRe, E. D.

2007-03-01

Signatures of nitric acid particles (NAP) in cold thick ice clouds have been derived from satellite observations. Most NAP are detected in the tropics (9 to 20% of clouds with T < 202.5 K). Higher occurrences were found in the rare midlatitudes very cold clouds. NAP occurrence increases as cloud temperature decreases, and NAP are more numerous in January than July. Comparisons of NAP and lightning distributions show that lightning seems to be the main source of the NOx, which forms NAP in cold clouds over continents. Qualitative comparisons of NAP with upper tropospheric humidity distributions suggest that NAP may play a role in the dehydration of the upper troposphere when the tropopause is colder than 195 K.

Methane from the Tropospheric Emission Spectrometer (TES)

Science.gov (United States)

Payne, Vivienne; Worden, John; Kulawik, Susan; Frankenberg, Christian; Bowman, Kevin; Wecht, Kevin

2012-01-01

TES V5 CH4 captures latitudinal gradients, regional variability and interannual variation in the free troposphere. V5 joint retrievals offer improved sensitivity to lower troposphere. Time series extends from 2004 to present. V5 reprocessing in progress. Upper tropospheric bias. Mitigated by N2O correction. Appears largely spatially uniform, so can be corrected. How to relate free-tropospheric values to surface emissions.

Characteristics of PEMFC operating at high current density with low external humidification

International Nuclear Information System (INIS)

Fan, Linhao; Zhang, Guobin; Jiao, Kui

2017-01-01

Highlights: • PEMFC with low humidity and high current density is studied by numerical simulation. • At high current density, water production lowers external humidification requirement. • A steady anode circulation status without external humidification is demonstrated. • The corresponding detailed internal water transfer path in the PEMFC is illustrated. • Counter-flow is superior to co-flow at low anode external humidification. - Abstract: A three-dimensional multiphase numerical model for proton exchange membrane fuel cell (PEMFC) is developed to study the fuel cell performance and water transport properties with low external humidification. The results show that the sufficient external humidification is necessary to prevent the polymer electrolyte dehydration at low current density, while at high current density, the water produced in cathode CL is enough to humidify the polymer electrolyte instead of external humidification by flowing back and forth between the anode and cathode across the membrane. Furthermore, a steady anode circulation status without external humidification is demonstrated in this study, of which the detailed internal water transfer path is also illustrated. Additionally, it is also found that the water balance under the counter-flow arrangement is superior to co-flow at low anode external humidification.

Functional short- and long-term effects of nasal CPAP with and without humidification on the ciliary function of the nasal respiratory epithelium.

Science.gov (United States)

Sommer, J Ulrich; Kraus, Marius; Birk, Richard; Schultz, Johannes D; Hörmann, Karl; Stuck, Boris A

2014-03-01

Continuous positive airway pressure (CPAP) is the gold standard in the treatment of obstructive sleep apnea (OSA), but its impact on ciliary function is unclear to date. Furthermore, CPAP is associated with numerous side effects related to the nose and upper airway. Humidified CPAP is used to relieve these symptoms, but again, little is known regarding its effect on ciliary function of the nasal respiratory epithelium. In this prospective, randomized, crossover trial, 31 patients with OSA (AHI >15/h) were randomized to two treatment arms: nasal continuous positive airway pressure (nCPAP) with humidification or nCPAP without humidification for one night in each modality to assess short-term effects of ciliary beat frequency (CBF) and mucus transport time (MTT) and consecutively for 8 weeks in each modality to assess long-term effects in a crossover fashion. The baseline CBF was 4.8 ± 0.6 Hz, and baseline MTT was 540 ± 221 s. After one night of CPAP with and without humidification, ciliary function increased moderately yet with statistical significance (p humidification did not differ statistically significant. Regarding long-term effects of CPAP, a statistically significant increase in ciliary function above the baseline level and above the short-term level was shown without humidification (7.2 ± 0.4 Hz; 402 ± 176 s; p humidification (9.3 ± 0.7 Hz; 313 ± 95 s; p humidification, nCPAP has moderate effects on short-term ciliary function of the nasal respiratory epithelium. However, a significant increase in ciliary function-both in terms of an increased CBF and a decreased MTT-was detected after long-term use. The effect was more pronounced when humidification was used during nCPAP.

Home-based humidification for mucositis in patients undergoing radical radiotherapy: preliminary report.

Science.gov (United States)

Morton, Randall P; Thomson, Vicki C; Macann, Andrew; Gerard, Catherine M; Izzard, Mark; Hay, K David

2008-04-01

Oropharyngeal mucositis is a frequent, severe complication of local irradiation for tumours in the head and neck. We postulated that heated humidification of inspired air via a nasal interface may palliate symptoms of mucositis by reducing the discomfort associated with dry, sticky secretions. We sought to review the effect of home-based humidification on hospital admissions and the patient reported experience of that humidification. This study was a retrospective review. A historical (control) group of patients did not receive home humidification at any stage (n = 55) and a study group (n = 53) received home humidification at or after the onset of grade 3 mucositis. A questionnaire was sent to study group patients to obtain information about their experience of using the humidifier at home. There were no demographic differences between the study and control groups, but the study group had significantly more advanced cancer (stage IV; p = .0307) and significantly higher total fractions and days treated (p humidification were admitted after starting that use (p humidification was of benefit, and 81% stated that it relieved mouth or throat pain. Humidification of inspired gas offers a simple, drug-free option for managing a number of the adverse mucosal effects of radiation and chemoradiation in head and neck cancer patients.

The Relative Importance of Random Error and Observation Frequency in Detecting Trends in Upper Tropospheric Water Vapor

Science.gov (United States)

Whiteman, David N.; Vermeesch, Kevin C.; Oman, Luke D.; Weatherhead, Elizabeth C.

2011-01-01

Recent published work assessed the amount of time to detect trends in atmospheric water vapor over the coming century. We address the same question and conclude that under the most optimistic scenarios and assuming perfect data (i.e., observations with no measurement uncertainty) the time to detect trends will be at least 12 years at approximately 200 hPa in the upper troposphere. Our times to detect trends are therefore shorter than those recently reported and this difference is affected by data sources used, method of processing the data, geographic location and pressure level in the atmosphere where the analyses were performed. We then consider the question of how instrumental uncertainty plays into the assessment of time to detect trends. We conclude that due to the high natural variability in atmospheric water vapor, the amount of time to detect trends in the upper troposphere is relatively insensitive to instrumental random uncertainty and that it is much more important to increase the frequency of measurement than to decrease the random error in the measurement. This is put in the context of international networks such as the Global Climate Observing System (GCOS) Reference Upper-Air Network (GRUAN) and the Network for the Detection of Atmospheric Composition Change (NDACC) that are tasked with developing time series of climate quality water vapor data.

Is humidification always necessary during noninvasive ventilation in the hospital?

Science.gov (United States)

Branson, Richard D; Gentile, Michael A

2010-02-01

Noninvasive ventilation (NIV) is a standard of care for the treatment of exacerbation of chronic obstructive pulmonary disease, to prevent intubation and reduce morbidity and mortality. The need for humidification of NIV gas is controversial. Some unique aspects of NIV conspire to alter the delivered humidity and airway function. In the presence of air leaks, unidirectional air flow dries the airways and increases airway resistance. Patient comfort is also a critical issue, as tolerance of NIV is often tied to patient comfort. This paper provides the arguments for and against routine humidification during NIV in the hospital setting. Data from clinical research demonstrate the effects of delivered humidification on relevant physiologic variables. The impact of humidification on NIV success/failure remains speculative.

A distribution law for relative humidity in the upper troposphere and lower stratosphere derived from three years of MOZAIC measurements

Directory of Open Access Journals (Sweden)

K. Gierens

1999-09-01

Full Text Available Data from three years of MOZAIC measurements made it possible to determine a distribution law for the relative humidity in the upper troposphere and lower stratosphere. Data amounting to 13.5% of the total were obtained in regions with ice supersaturation. Troposphere and stratosphere are distinguished by an ozone concentration of 130 ppbv as threshold. The probability of measuring a certain amount of ice supersaturation in the troposphere decreases exponentially with the degree of ice supersaturation. The probability of measuring a certain relative humidity in the stratosphere (both with respect to water and ice decreases exponentially with the relative humidity. A stochastic model that naturally leads to the exponential distribution is provided. Mean supersaturation in the troposphere is about 15%, whereas ice nucleation requires 30% supersaturation on the average. This explains the frequency of regions in which aircraft induce persistent contrails but which are otherwise free of clouds. Ice supersaturated regions are 3-4 K colder and contain more than 50% more vapour than other regions in the upper troposphere. The stratospheric air masses sampled are dry, as expected, having mean relative humidity over water of 12% and over ice of 23%, respectively. However, 2% of the stratospheric data indicate ice supersaturation. As the MOZAIC measurements have been obtained on commercial flights mainly between Europe and North America, the data do not provide a complete global picture, but the exponential character of the distribution laws found is probably valid globally. Since water vapour is the most important greenhouse gas and since it might enhance the anthropogenic greenhouse effects via positive feedback mechanisms, it is important to represent its distribution correctly in climate models. The discovery of the distribution law of the relative humidity makes possible simple tests to show whether the hydrological cycle in climate models is

Met UM Upper-tropospheric summer jet teleconnections: A model assessment

Science.gov (United States)

Joao Carvalho, Maria; Rodriguez, Jose; Milton, Sean

2017-04-01

The upper tropospheric jet stream has been documented to act as a waveguide (Hoskins and Ambrizzi, 1993) and supporting quasi-stationary Rossby waves (Schubert et al. 2011). These have been associated with remote effects in surface level weather such as rainfall anomalies in the East Asian Summer Monsoon as well as extreme temperature events. The goal of this work was to analyse the intraseasonal to interannual upper level boreal summer jet variability and its coupling with low level atmospheric dynamics within the Met Office Unified Model using climate runs. Using the Wallace and Gutzler (1981) proposed approach to find teleconnection patterns on the 200 hPa level wind, lead-lag correlation and Empirical Orthogonal Function analysis on the upper-level jet and relating the results with surface weather variables as well as dynamical variables, it was found that the model presents too strong jet variability, particularly in the tropical region and. In addition, the model presents high teleconnectivity hotspots with higher importance in areas such as the Mediterranean and Caspian Sea which are important source areas for Rossby Waves. Further to this, the model was found to produce an area of teleconnectivity between the tropical Atlantic and western Africa which is not observed in the reanalysis but coexists with long lasting precipitation biases. As comparison for the model results, ERA-Interim circulation and wind data and the TRMM precipitation dataset were used. In order to assess the relative importance of relevant model parameters in the biases and process errors, work is currently underway using perturbed model parameter ensembles.

Artificial humidification for the mechanically ventilated patient

OpenAIRE

Selvaraj, Nelson

2010-01-01

Caring for patients who are mechanically ventilated poses many\\ud challenges for critical care nurses. It is important to humidify the\\ud patient’s airways artificially to prevent complications such as\\ud ventilator-associated pneumonia. There is no gold standard to\\ud determine which type of humidification is best for patients who\\ud are artificially ventilated. This article provides an overview of\\ud commonly used artificial humidification for mechanically ventilated\\ud patients and discuss...

Humidification of inspired gases during mechanical ventilation.

Science.gov (United States)

Gross, J L; Park, G R

2012-04-01

Humidification of inspired gas is mandatory for all mechanically ventilated patients to prevent secretion retention, tracheal tube blockage and adverse changes occurring to the respiratory tract epithelium. However, the debate over "ideal" humidification continues. Several devices are available that include active and passive heat and moisture exchangers and hot water humidifiers Each have their advantages and disadvantages in mechanically ventilated patients. This review explores each device in turn and defines their role in clinical practice.

CARIBIC observations of gaseous mercury in the upper troposphere and lower stratosphere

Directory of Open Access Journals (Sweden)

Slemr F.

2013-04-01

Full Text Available A unique set of gaseous mercury measurements in the upper troposphere and lower stratosphere (UT/LS has been obtained during the monthly CARIBIC (www.caribic-atmospheric.com flights since May 2005. The passenger Airbus 340-600 of Lufthansa covered routes to the Far East, North America, India, and the southern hemisphere. The accompanying measurements of CO, O3, NOy, H2O, aerosols, halocarbons, hydrocarbons, greenhouse gases, and several other parameters as well as backward trajectories enable a detailed analysis of these measurements. Speciation tests have shown that the CARIBIC measurements represent a good approximation of total gaseous mercury (TGM concentrations. Above the tropopause TGM always decrease with increasing potential vorticity (PV and O3 which implies its conversion to particle bound mercury. The observation of the lowest TGM concentrations at the highest particle concentrations in the stratosphere provides further evidence for such conversion. We will show how a seasonally dependent conversion rate could be derived using concomitantly measured SF6 mixing ratios as a timer. Tropospheric mercury data suggest the existence of a decreasing trend in the northern hemisphere whose size is comparable with the trend derived from long-term measurements by ship cruises, at Cape Point (South Africa and Mace Head (Ireland.

Origins of Tropospheric Ozone Interannual Variation (IAV) over Reunion: A Model Investigation

Science.gov (United States)

Liu, Junhua; Rodriguez, Jose M.; Thompson, Anne M.; Logan, Jennifer A.; Douglass, Anne R.; Olsen, Mark A.; Steenrod, Stephen D.; Posny, Francoise

2016-01-01

Observations from long-term ozonesonde measurements show robust variations and trends in the evolution of ozone in the middle and upper troposphere over Reunion Island (21.1 degrees South Latitude, 55.5 degrees East Longitude) in June-August. Here we examine possible causes of the observed ozone variation at Reunion Island using hindcast simulations by the stratosphere-troposphere Global Modeling Initiative chemical transport model for 1992-2014, driven by assimilated Modern-Era Retrospective Analysis for Research and Applications (MERRA) meteorological fields. Reunion Island is at the edge of the subtropical jet, a region of strong stratospheric-tropospheric exchange. Our analysis implies that the large interannual variation (IAV) of upper tropospheric ozone over Reunion is driven by the large IAV of the stratospheric influence. The IAV of the large-scale, quasi-horizontal wind patterns also contributes to the IAV of ozone in the upper troposphere. Comparison to a simulation with constant emissions indicates that increasing emissions do not lead to the maximum trend in the middle and upper troposphere over Reunion during austral winter implied by the sonde data. The effects of increasing emission over southern Africa are limited tothe lower troposphere near the surface in August-September.

Observations of HO{sub x}, NO{sub x}, NO{sub y}, and CO. NO{sub x} control of the photochemical production and removal of ozone in the upper troposphere

Energy Technology Data Exchange (ETDEWEB)

Wennberg, P O; Hanisco, T F; Lanzendorf, E L; Jaegle, L Y; Jacob, D J; Cohen, R C; Anderson, J G [Harvard Univ., Cambridge, MA (United States). Dept. of Chemistry; [Dept. of Earth and Planetary Sciences; Fahey, D W; Gao, R S; Keim, E R [National Oceanic and Atmospheric Administration, Boulder, CO (United States). Aeronomy Lab.; others, and

1998-12-31

In-situ measurements from the NASA ER2 aircraft provide the first observations of the odd-hydrogen radicals in the upper troposphere. A new photochemical model was constructed to explain the observations. Based on the model, the way of NO{sub x} influence on the photochemistry of ozone was determined. The measurements also explain why high NO{sub x}/NO{sub y} ratios are sustained in the upper troposphere. (R.P.)

Observations of HO{sub x}, NO{sub x}, NO{sub y}, and CO. NO{sub x} control of the photochemical production and removal of ozone in the upper troposphere

Energy Technology Data Exchange (ETDEWEB)

Wennberg, P.O.; Hanisco, T.F.; Lanzendorf, E.L.; Jaegle, L.Y.; Jacob, D.J.; Cohen, R.C.; Anderson, J.G. [Harvard Univ., Cambridge, MA (United States). Dept. of Chemistry]|[Dept. of Earth and Planetary Sciences; Fahey, D.W.; Gao, R.S.; Keim, E.R. [National Oceanic and Atmospheric Administration, Boulder, CO (United States). Aeronomy Lab.; and others

1997-12-31

In-situ measurements from the NASA ER2 aircraft provide the first observations of the odd-hydrogen radicals in the upper troposphere. A new photochemical model was constructed to explain the observations. Based on the model, the way of NO{sub x} influence on the photochemistry of ozone was determined. The measurements also explain why high NO{sub x}/NO{sub y} ratios are sustained in the upper troposphere. (R.P.)

The effects of deep convection on the concentration and size distribution of aerosol particles within the upper troposphere: A case study

Science.gov (United States)

Yin, Yan; Chen, Qian; Jin, Lianji; Chen, Baojun; Zhu, Shichao; Zhang, Xiaopei

2012-11-01

A cloud resolving model coupled with a spectral bin microphysical scheme was used to investigate the effects of deep convection on the concentration and size distribution of aerosol particles within the upper troposphere. A deep convective storm that occurred on 1 December, 2005 in Darwin, Australia was simulated, and was compared with available radar observations. The results showed that the radar echo of the storm in the developing stage was well reproduced by the model. Sensitivity tests for aerosol layers at different altitudes were conducted in order to understand how the concentration and size distribution of aerosol particles within the upper troposphere can be influenced by the vertical transport of aerosols as a result of deep convection. The results indicated that aerosols originating from the boundary layer can be more efficiently transported upward, as compared to those from the mid-troposphere, due to significantly increased vertical velocity through the reinforced homogeneous freezing of droplets. Precipitation increased when aerosol layers were lofted at different altitudes, except for the case where an aerosol layer appeared at 5.4-8.0 km, in which relatively more efficient heterogeneous ice nucleation and subsequent Wegener-Bergeron-Findeisen process resulted in more pronounced production of ice crystals, and prohibited the formation of graupel particles via accretion. Sensitivity tests revealed, at least for the cases considered, that the concentration of aerosol particles within the upper troposphere increased by a factor of 7.71, 5.36, and 5.16, respectively, when enhanced aerosol layers existed at 0-2.2 km, 2.2-5.4 km, and 5.4-8.0 km, with Aitken mode and a portion of accumulation mode (0.1-0.2μm) particles being the most susceptible to upward transport.

Acetylene C2H 2 retrievals from MIPAS data and regions of enhanced upper tropospheric concentrations in August 2003

Directory of Open Access Journals (Sweden)

V. P. Kanawade

2011-10-01

Full Text Available Acetylene (C2H2 volume mixing ratios (VMRs have been successfully retrieved from the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS Level 1B radiances during August 2003, providing the first global map of such data and ratios to CO in the literature. The data presented here contain most information between 300 hPa and 100 hPa with systematic errors less than 10% at the upper levels. Random errors per point are less than 15% at lower levels and are closer to 30% at 100 hPa. Global distributions of the C2H2 and C2H2/CO ratio confirm significant features associated with both the Asian monsoon anticyclone and biomass burning for this important hydrocarbon in a characteristic summer month (August 2003, showing tight correlations regionally, particularly at lower to medium values, but globally emphasising the differences between sources and lifetimes of CO and C2H2. The correlations are seen to be particularly disturbed in the regions of highest C2H2 concentrations, indicating variability in the surface emissions or fast processing. A strong isolation of C2H2 within the Asian monsoon anticyclone is observed, evidencing convective transport into the upper troposphere, horizontal advection within the anticyclone at 200 hPa, distinct gradients at the westward edge of the vortex and formation of a secondary dynamical feature from the eastward extension of the anticyclone outflow over the Asian Pacific. Ratios of C2H2/CO are consistent with the evidence from the cross-sections that the C2H2 is uplifted rapidly in convection. Observations are presented of enhanced C2H2 associated with the injection from biomass burning into the upper troposphere and the outflow from Africa at 200 hPa into both the Atlantic and Indian Oceans. In the biomass burning regions, C2H2 and CO are well correlated, but the uplift is less marked and peaks at lower altitudes compared to the strong effects observed in the Asian monsoon anticyclone. Ratios of C2H2/CO

Nasal inflammation in sleep apnoea patients using CPAP and effect of heated humidification.

Science.gov (United States)

Koutsourelakis, I; Vagiakis, E; Perraki, E; Karatza, M; Magkou, C; Kopaka, M; Roussos, C; Zakynthinos, S

2011-03-01

Nasal continuous positive airway pressure (CPAP) can cause undesirable nasal symptoms, such as congestion to obstructive sleep apnoea (OSA) patients, whose symptoms can be attenuated by the addition of heated humidification. However, neither the nature of nasal symptoms nor the effect of heated humidification on nasal pathophysiology and pathology are convincingly known. 20 patients with OSA on nasal CPAP who exhibited symptomatic nasal obstruction were randomised to receive either 3 weeks of CPAP treatment with heated humidification or 3 weeks of CPAP treatment with sham-heated humidification, followed by 3 weeks of the opposite treatment, respectively. Nasal symptom score, nasal resistance, nasal lavage interleukin-6, interleukin-12 and tumour necrosis factor-α and nasal mucosa histopathology were assessed at baseline and after each treatment arm. Heated humidification in comparison with sham-heated humidification was associated with decrease in nasal symptomatology, resistance and lavage cytokines, and attenuation of inflammatory cell infiltration and fibrosis of the nasal mucosa. In conclusion, nasal obstruction of OSA patients on CPAP treatment is inflammatory in origin and the addition of heated humidification decreases nasal resistance and mucosal inflammation.

Evidence of a 50-year increase in tropospheric ozone in Upper Bavaria

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M. Schmidt

Full Text Available In a series of ozone-sonde soundings at the Hohenpeißenberg observatory, starting in 1967, the most striking features are increases of sim2.2% per year in all tropospheric heights up to 8 km during the past 24 years. These facts have recently been published and discussed by several authors. In this paper, we present some evidence for the increase of tropospheric ozone concentrations during the past 50 years 1940-1990 in the territory of the northern edge of the Bavarian Alps, including the Hohenpeißenberg data. In December 1940 and August 1942, probably the first exact wet-chemical vertical soundings of ozone up to 9 km height were made by an aircraft in the region mentioned. These results were published in the earlier literature. We have converted the results of the flights on 4 days in December 1940 and on 6 days in August 1942 to modern units and have compared them with the Hohenpeißenberg ozone-sonde data of the December and August months. We also compared the data at the ground with the August results of Paris-Montsouris 1886-1898. Our results show an increase of ozone concentration at all tropospheric heights in Upper Bavaria during the past 50 years, compared with the Montsouris data in August during the past 105 years. In the recently published papers, the increases since 1967 were approximated linearly.Our results, extended to the past, show non-linear trends, with steeper increases since 1975-1979. Possible reasons for these findings are discussed. Quite recently (in case of the December months since 1986/87, the August months since 1990, the ozone mixing ratios at and above Hohenpeißenberg seem to have decreased.

Evidence of a 50-year increase in tropospheric ozone in Upper Bavaria

Directory of Open Access Journals (Sweden)

M. Schmidt

1994-12-01

Full Text Available In a series of ozone-sonde soundings at the Hohenpeißenberg observatory, starting in 1967, the most striking features are increases of \\sim2.2% per year in all tropospheric heights up to 8 km during the past 24 years. These facts have recently been published and discussed by several authors. In this paper, we present some evidence for the increase of tropospheric ozone concentrations during the past 50 years 1940-1990 in the territory of the northern edge of the Bavarian Alps, including the Hohenpeißenberg data. In December 1940 and August 1942, probably the first exact wet-chemical vertical soundings of ozone up to 9 km height were made by an aircraft in the region mentioned. These results were published in the earlier literature. We have converted the results of the flights on 4 days in December 1940 and on 6 days in August 1942 to modern units and have compared them with the Hohenpeißenberg ozone-sonde data of the December and August months. We also compared the data at the ground with the August results of Paris-Montsouris 1886-1898. Our results show an increase of ozone concentration at all tropospheric heights in Upper Bavaria during the past 50 years, compared with the Montsouris data in August during the past 105 years. In the recently published papers, the increases since 1967 were approximated linearly.Our results, extended to the past, show non-linear trends, with steeper increases since 1975-1979. Possible reasons for these findings are discussed. Quite recently (in case of the December months since 1986/87, the August months since 1990, the ozone mixing ratios at and above Hohenpeißenberg seem to have decreased.

MIPAS measurements of upper tropospheric C2H6 and O3 during the southern hemispheric biomass burning season in 2003

Directory of Open Access Journals (Sweden)

T. Steck

2007-11-01

Full Text Available Under cloud free conditions, the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS provides measurements of spectrally resolved limb radiances down to the upper troposphere. These are used to infer global distributions of mixing ratios of atmospheric constituents in the upper troposphere and the stratosphere. From 21 October to 12 November 2003, MIPAS observed enhanced amounts of upper tropospheric C2H6 (up to about 400 pptv and ozone (up to about 80 ppbv. The absolute values of C2H6, however, may be systematically low by about 30% due to uncertainties of the spectroscopic data used. By means of trajectory calculations, the enhancements observed in the southern hemisphere are, at least partly, attributed to a biomass burning plume, which covers wide parts of the Southern hemisphere, from South America, the Atlantic Ocean, Africa, the Indian Ocean to Australia. The chemical composition of the part of the plume-like pollution belt associated with South American fires, where rainforest burning is predominant appears different from the part of the plume associated with southern African savanna burning. In particular, African savanna fires lead to a larger ozone enhancement than equatorial American fires. In this analysis, MIPAS observations of high ozone were disregarded where low CFC-11 (below 245 pptv was observed, because this hints at a stratospheric component in the measured signal. Different type of vegetation burning (flaming versus smouldering combustion has been identified as a candidate explanation for the different plume compositions.

Routine use of humidification with nasal continuous positive airway pressure.

Science.gov (United States)

Worsnop, C J; Miseski, S; Rochford, P D

2010-09-01

Heated humidification can reduce nasal symptoms caused by continuous positive airway pressure (CPAP) treatment, but its routine use has not been studied over the medium term in a randomized controlled trial. The aim of this study is to determine if heated humidification would reduce nasal symptoms and improve adherence with CPAP treatment in all patients with sleep apnoea irrespective of whether they had nasal symptoms initially. A randomized, parallel group design. Patients were treated for 3 months with a Fisher & Paykel HC201 pump with built-in heated humidification, or with the heater disabled and without water. Adherence was measured with a timer built into the pumps. Nasal symptoms were measured with a 10-cm visual analogue scale. There were 25 in the humidification group and 29 in the non-humidification group. After 12 weeks mean (standard deviation) adherence with CPAP was 4.7 (2.4) and 4.5 (2.2) hours per night respectively. Nasal symptoms that were reduced were nose blocked* 6 (12), 18 (26); sneezing* 4 (8), 15 (25); dry nose* 8 (12), 24 (33); stuffy nose* 7 (14), 22(31); dry mouth* 13 (18), 33(36); and runny nose* 6 (17), 14 (29). Parameters marked with an asterisk '*' had P humidification with CPAP in all patients with sleep apnoea reduced nasal symptoms, but did not improve adherence. © 2010 The Authors. Internal Medicine Journal © 2010 Royal Australasian College of Physicians.

Effect of cathode gas humidification on performance and durability of Solid Oxide Fuel Cells

DEFF Research Database (Denmark)

Nielsen, Jimmi; Hagen, Anke; Liu, Yi-Lin

2010-01-01

The effect of cathode inlet gas humidification was studied on single anode supported Solid Oxide Fuel Cells (SOFC's). The studied cells were Risø 2 G and 2.5 G. The former consists of a LSM:YSZ composite cathode, while the latter consists of a LSCF:CGO composite cathode on a CGO protection layer....... The humidification effect was found to be dependent on both the degree of humidification and the cathode polarization. No significant effect of humidification was found at OCV which rules out the possibility of a traditional poisoning effect with a blocking of active sites. Post-mortem high resolution FEG......-SEM analysis showed clear changes at and around the cathode/electrolyte contact area. In contrast to Risø 2 G cells, a very high tolerance towards humidification of cathode gas air was observed for Risø 2.5 G cells with no detectable effect of humidification even when the humidification was as high as 12.8 mol%...

Airway Humidification Reduces the Inflammatory Response During Mechanical Ventilation.

Science.gov (United States)

Jiang, Min; Song, Jun-Jie; Guo, Xiao-Li; Tang, Yong-Lin; Li, Hai-Bo

2015-12-01

Currently, no clinical or animal studies have been performed to establish the relationship between airway humidification and mechanical ventilation-induced lung inflammatory responses. Therefore, an animal model was established to better define this relationship. Rabbits (n = 40) were randomly divided into 6 groups: control animals, sacrificed immediately after anesthesia (n = 2); dry gas group animals, subjected to mechanical ventilation for 8 h without humidification (n = 6); and experimental animals, subjected to mechanical ventilation for 8 h under humidification at 30, 35, 40, and 45°C, respectively (n = 8). Inflammatory cytokines in the bronchi alveolar lavage fluid (BALF) were measured. The integrity of the airway cilia and the tracheal epithelium was examined by scanning and transmission electron microscopy, respectively. Peripheral blood white blood cell counts and the wet to dry ratio and lung pathology were determined. Dry gas group animals showed increased tumor necrosis factor alpha levels in BALF compared with control animals (P humidification temperature was increased to 40°C. Scanning and transmission electron microscopy analysis revealed that cilia integrity was maintained in the 40°C groups. Peripheral white blood cell counts were not different among those groups. Compared with control animals, the wet to dry ratio was significantly elevated in the dry gas group (P humidification at 40°C resulted in reduced pathologic injury compared with the other groups based on the histologic score. Pathology and reduced inflammation observed in animals treated at 40°C was similar to that observed in the control animals, suggesting that appropriate humidification reduced inflammatory responses elicited as a consequence of mechanical ventilation, in addition to reducing damage to the cilia and reducing water loss in the airway. Copyright © 2015 by Daedalus Enterprises.

Membrane humidification--a new method for humidification of respiratory gases in ventilator treatment of neonates.

Science.gov (United States)

Hanssler, L; Tennhoff, W; Roll, C

1992-01-01

A humidifier system for neonatology that functions according to the 'membrane humidification' principle was subjected to a performance test in our laboratory. Humidification and heating of the respiratory gases took place in a module consisting of a net of hollow fibres placed inside the incubator. In 18 measurement combinations flow, respiratory gas temperature, and incubator temperature were varied. At respiratory gas temperatures within the range of 33-37 degrees C the minimum international standard for the absolute air humidity in the respiratory gas was achieved or exceeded in all measurements. No controlled clinical tests regarding the importance and long term effects of different temperatures and different humidity levels in the inspiratory air are yet available for the ventilation treatment of neonates. PMID:1444554

Correction Technique for Raman Water Vapor Lidar Signal-Dependent Bias and Suitability for Water Wapor Trend Monitoring in the Upper Troposphere

Science.gov (United States)

Whiteman, D. N.; Cadirola, M.; Venable, D.; Calhoun, M.; Miloshevich, L; Vermeesch, K.; Twigg, L.; Dirisu, A.; Hurst, D.; Hall, E.;

Inertia gravity waves in the upper troposphere during the MaCWAVE winter campaign. Part I. Observations with collocated radars

Energy Technology Data Exchange (ETDEWEB)

Hoffmann, P.; Serafimovich, A.; Peters, D.; Latteck, R. [Leibniz-Inst. fuer Atmosphaerenphysik, Kuehlungsborn (Germany); Dalin, P. [Swedish Inst. of Space Physics, Kiruna (Sweden); Goldberg, R. [NASA/Goddard Space Flight Center, Greenbelt, MD (United States)

2006-07-01

During the MaCWAVE campaign, combined rocket, radiosonde and ground-based measurements have been performed at the Norwegian Andoeya rocket range (ARR) near Andenes and the Swedish rocket range (ESRANGE) near Kiruna in January 2003 to study gravity waves in the vicinity of the Scandinavian mountain ridge. The investigations presented here are mainly based on the evaluation of continuous radar measurements with the ALWIN VHP radar in the upper troposphere/ lower stratosphere at Andenes (69.3 N, 16.0 E) and the ESRAD VHP radar near Kiruna (67.9 N, 21.9 E). Both radars are separated by about 260 km. Based on wavelet transformations of both data sets, the strongest activity of inertia gravity waves in the upper troposphere has been detected during the first period from 24-26 January 2003 with dominant vertical wavelengths of about 4-5 km as well as with dominant observed periods of about 13-14 h for the altitude range between 5 and 8 km under the additional influence of mountain waves. The results show the appearance of dominating inertia gravity waves with characteristic horizontal wavelengths of {proportional_to}200 km moving in the opposite direction than the mean background wind. The results show the appearance of dominating inertia gravity waves with intrinsic periods in the order of {proportional_to}5 h and with horizontal wavelengths of 200 km, moving in the opposite direction than the mean background wind. From the derived downward energy propagation it is supposed, that these waves are likely generated by a jet streak in the upper troposphere. The parameters of the jet-induced gravity waves have been estimated at both sites separately. The identified gravity waves are coherent at both locations and show higher amplitudes on the east-side of the Scandinavian mountain ridge, as expected by the influence of mountains. (orig.)

Heated air humidification versus cold air nebulization in newly tracheostomized patients.

Science.gov (United States)

Birk, Richard; Händel, Alexander; Wenzel, Angela; Kramer, Benedikt; Aderhold, Christoph; Hörmann, Karl; Stuck, Boris A; Sommer, J Ulrich

2017-12-01

After tracheostomy, the airway lacks an essential mechanism for warming and humidifying the inspired air with the consequent functional impairment and discomfort. The purpose of this study was to compare airway hydration with cold-air nebulization versus heated high-flow humidification on medical interventions and tracheal ciliary beat frequency (CBF). Newly tracheostomized patients (n = 20) were treated either with cold-air nebulization or heated humidification. The number of required tracheal suctioning procedures to clean the trachea and tracheal CBF were assessed. The number of required suctions per day was significantly lower in the heated humidification group with medians 3 versus 5 times per day. Mean CBF was significantly higher in the heated humidification group (6.36 ± 1.49 Hz) compared to the cold-air nebulization group (3.99 ± 1.39 Hz). The data suggest that heated humidification enhanced mucociliary transport leading to a reduced number of required suctioning procedures in the trachea, which may improve postoperative patient care. © 2017 The Authors Head & Neck Published by Wiley Periodicals, Inc.

Comparison of two humidification systems for long-term noninvasive mechanical ventilation.

Science.gov (United States)

Nava, S; Cirio, S; Fanfulla, F; Carlucci, A; Navarra, A; Negri, A; Ceriana, P

2008-08-01

There is no consensus concerning the best system of humidification during long-term noninvasive mechanical ventilation (NIMV). In a technical pilot randomised crossover 12-month study, 16 patients with stable chronic hypercapnic respiratory failure received either heated humidification or heat and moisture exchanger. Compliance with long-term NIMV, airway symptoms, side-effects and number of severe acute pulmonary exacerbations requiring hospitalisation were recorded. Two patients died. Intention-to-treat statistical analysis was performed on 14 patients. No significant differences were observed in compliance with long-term NIMV, but 10 out of 14 patients decided to continue long-term NIMV with heated humidification at the end of the trial. The incidence of side-effects, except for dry throat (significantly more often present using heat and moisture exchanger), hospitalisations and pneumonia were not significantly different. In the present pilot study, the use heated humidification and heat and moisture exchanger showed similar tolerance and side-effects, but a higher number of patients decided to continue long-term noninvasive mechanical ventilation with heated humidification. Further larger studies are required in order to confirm these findings.

Observations of fine-scale transport structure in the upper troposphere from the High-performance Instrumented Airborne Platform for Environmental Research

Science.gov (United States)

Bowman, Kenneth P.; Pan, Laura L.; Campos, Teresa; Gao, Rushan

2007-09-01

The Progressive Science Mission in December 2005 was the first research use of the new NCAR High-performance Instrumented Airborne Platform for Environmental Research (HIAPER) aircraft. The Stratosphere-Troposphere Analyses of Regional Transport (START) component of the mission was designed to investigate the dynamical and chemical structure of the upper troposphere and lower stratosphere. Flight 5 of the Progressive Science mission was a START flight that sampled near the tropopause in an area between the main jet stream and a large, quasi-stationary, cutoff low. The large-scale flow in this region was characterized by a hyperbolic (saddle) point. In this study the in situ measurements by HIAPER are combined with flow analyses and satellite data to investigate the quasi-isentropic stirring of trace species in the upper troposphere. As expected from theoretical considerations, strong stretching and folding deformation of the flow near the hyperbolic point resulted in rapid filamentation of air masses and sharp gradients of constituents. Calculations of the stirring using operational meteorological analyses from the NCEP Global Forecast System model produced excellent agreement with HIAPER and satellite observations of trace species. Back trajectories indicate that elevated ozone levels in some filaments likely came from a large stratospheric intrusion that occurred upstream in the jet over the north Pacific Ocean. The methods presented here can be used with operational forecasts for future flight planning.

Top-of-atmosphere radiative forcing affected by brown carbon in the upper troposphere

Science.gov (United States)

Zhang, Yuzhong; Forrister, Haviland; Liu, Jiumeng; Dibb, Jack; Anderson, Bruce; Schwarz, Joshua P.; Perring, Anne E.; Jimenez, Jose L.; Campuzano-Jost, Pedro; Wang, Yuhang; Nenes, Athanasios; Weber, Rodney J.

2017-07-01

Carbonaceous aerosols affect the global radiative balance by absorbing and scattering radiation, which leads to warming or cooling of the atmosphere, respectively. Black carbon is the main light-absorbing component. A portion of the organic aerosol known as brown carbon also absorbs light. The climate sensitivity to absorbing aerosols rapidly increases with altitude, but brown carbon measurements are limited in the upper troposphere. Here we present aircraft observations of vertical aerosol distributions over the continental United States in May and June 2012 to show that light-absorbing brown carbon is prevalent in the troposphere, and absorbs more short-wavelength radiation than black carbon at altitudes between 5 and 12 km. We find that brown carbon is transported to these altitudes by deep convection, and that in-cloud heterogeneous processing may produce brown carbon. Radiative transfer calculations suggest that brown carbon accounts for about 24% of combined black and brown carbon warming effect at the tropopause. Roughly two-thirds of the estimated brown carbon forcing occurs above 5 km, although most brown carbon is found below 5 km. The highest radiative absorption occurred during an event that ingested a wildfire plume. We conclude that high-altitude brown carbon from biomass burning is an unappreciated component of climate forcing.

Retrieval of water vapor vertical distributions in the upper troposphere and the lower stratosphere from SCIAMACHY limb measurements

OpenAIRE

Rozanov, A.; Weigel, K.; Bovensmann, H.; Dhomse, S.; Eichmann, K.-U.; Kivi, R.; Rozanov, V.; Vömel, H.; Weber, M.; Burrows, J. P.

2011-01-01

This study describes the retrieval of water vapor vertical distributions in the upper troposphere and lower stratosphere (UTLS) altitude range from space-borne observations of the scattered solar light made in limb viewing geometry. First results using measurements from SCIAMACHY (Scanning Imaging Absorption spectroMeter for Atmospheric CHartographY) aboard ENVISAT (Environmental Satellite) are presented here. In previous publications, the retrieval of water vapor vertical ...

Global distribution of upper tropospheric formic acid from the ACE-FTS

Directory of Open Access Journals (Sweden)

G. González Abad

2009-10-01

Full Text Available We present the first near global upper tropospheric distribution of formic acid (HCOOH observed from space using solar occultation measurements from the Fourier transform spectrometer (FTS on board the Atmospheric Chemistry Experiment (ACE satellite. Using a new set of spectroscopic line parameters recently published for formic acid by Vander Auwera et al. (2007 and Perrin and Vander Auwera (2007, we have retrieved the concentrations of HCOOH between 5 km and the tropopause for ACE-FTS observations from February 2004 to September 2007. We observe a significant seasonal dependence for the HCOOH concentrations related to vegetation growth and biomass burning. We estimate an emission ratio of 0.0051±0.0015 for HCOOH relative to CO for tropical South American fires using a selected set of data for September 2004. Results from the balloon-borne MkIV Fourier transform spectrometer are also presented and compared with the ACE measurements.

Stratosphere-troposphere exchange in a summertime extratropical low: analysis

Directory of Open Access Journals (Sweden)

J. Brioude

2006-01-01

Full Text Available Ozone and carbon monoxide measurements sampled during two commercial flights in airstreams of a summertime midlatitude cyclone are analysed with a Lagrangian-based study (backward trajectories and a Reverse Domain Filling technique to gain a comprehensive understanding of transport effects on trace gas distributions. The study demonstrates that summertime cyclones can be associated with deep stratosphere-troposphere transport. A tropopause fold is sampled twice in its life cycle, once in the lower troposphere (O3≃100 ppbv; CO≃90 ppbv in the dry airstream of the cyclone, and again in the upper troposphere (O3≃200 ppbv; CO≃90 ppbv on the northern side of the large scale potential vorticity feature associated with baroclinic development. In agreement with the maritime development of the cyclone, the chemical composition of the anticyclonic portion of the warm conveyor belt outflow (O3≃40 ppbv; CO≃85 ppbv corresponds to the lowest mixing ratios of both ozone and carbon monoxide in the upper tropospheric airborne observations. The uncertain degree of confidence of the Lagrangian-based technique applied to a 100 km segment of upper level airborne observations with high ozone (200 ppbv and relatively low CO (80 ppbv observed northwest of the cyclone prevents identification of the ozone enrichment process of air parcels embedded in the cyclonic part of the upper level outflow of the warm conveyor belt. Different hypotheses of stratosphere-troposphere exchange are discussed.

Low temperature humidification dehumidification desalination process

International Nuclear Information System (INIS)

Al-Enezi, Ghazi; Ettouney, Hisham; Fawzy, Nagla

2006-01-01

The humidification dehumidification desalination process is viewed as a promising technique for small capacity production plants. The process has several attractive features, which include operation at low temperature, ability to utilize sustainable energy sources, i.e. solar and geothermal, and requirements of low technology level. This paper evaluates the characteristics of the humidification dehumidification desalination process as a function of operating conditions. A small capacity experimental system is used to evaluate the process characteristics as a function of the flow rate of the water and air streams, the temperature of the water stream and the temperature of the cooling water stream. The experimental system includes a packed humidification column, a double pipe glass condenser, a constant temperature water circulation tank and a chiller for cooling water. The water production is found to depend strongly on the hot water temperature. Also, the water production is found to increase upon the increase of the air flow rate and the decrease of the cooling water temperature. The measured air and water temperatures, air relative humidity and the flow rates are used to calculate the air side mass transfer coefficient and the overall heat transfer coefficient. Measured data are found to be consistent with previous literature results

Inertia gravity waves in the upper troposphere during the MaCWAVE winter campaign – Part I: Observations with collocated radars

Directory of Open Access Journals (Sweden)

P. Hoffmann

2006-11-01

Full Text Available During the {MaCWAVE} campaign, combined rocket, radiosonde and ground-based measurements have been performed at the Norwegian Andøya Rocket Range (ARR near Andenes and the Swedish Rocket Range (ESRANGE near Kiruna in January 2003 to study gravity waves in the vicinity of the Scandinavian mountain ridge. The investigations presented here are mainly based on the evaluation of continuous radar measurements with the ALWIN VHF radar in the upper troposphere/ lower stratosphere at Andenes (69.3° N, 16.0° E and the ESRAD VHF radar near Kiruna (67.9° N, 21.9° E. Both radars are separated by about 260 km. Based on wavelet transformations of both data sets, the strongest activity of inertia gravity waves in the upper troposphere has been detected during the first period from 24–26 January 2003 with dominant vertical wavelengths of about 4–5 km as well as with dominant observed periods of about 13–14 h for the altitude range between 5 and 8 km under the additional influence of mountain waves. The results show the appearance of dominating inertia gravity waves with characteristic horizontal wavelengths of ~200 km moving in the opposite direction than the mean background wind. The results show the appearance of dominating inertia gravity waves with intrinsic periods in the order of ~5 h and with horizontal wavelengths of 200 km, moving in the opposite direction than the mean background wind. From the derived downward energy propagation it is supposed, that these waves are likely generated by a jet streak in the upper troposphere. The parameters of the jet-induced gravity waves have been estimated at both sites separately. The identified gravity waves are coherent at both locations and show higher amplitudes on the east-side of the Scandinavian mountain ridge, as expected by the influence of mountains.

Theoretical design strategies of bipolar membrane fuel cell with enhanced self-humidification behavior

Science.gov (United States)

Li, Qiushi; Gong, Jian; Peng, Sikan; Lu, Shanfu; Sui, Pang-Chieh; Djilali, Ned; Xiang, Yan

2016-03-01

The bipolar membrane fuel cells (BPMFCs), which have a unique acid-alkaline jointed membrane electrode assembly (MEA) structure, have demonstrated their great potential for self-humidification during operation. Although the self-humidification ability of such bipolar membranes (BPMs) has recently been validated by a one-dimensional BPM model, the transport mechanism and the formation of self-humidification in the MEAs are not well understood. In the present study, a two-dimensional cross-channel MEA model is developed to elucidate the mechanisms and enhancement of water transport on self-humidification with comprehensive consideration of the three electrochemical reaction zones. The water-formation interface model has been successfully investigated by theoretical and experimental interface reaction kinetics, streamlines of water flux present the formation process and mechanism of self-humidification. A critical current (voltage) value, beyond which self-humidification is initiated, is identified. It is also found that such critical current (voltage) can be adjusted by changing the membrane thickness and the water uptake property of the ionomer. It is concluded that fabricating BPMs with proper membrane thickness and water uptake property are effective strategies to enhance the water management and cell performance in BPMFCs.

On the Climate Impacts of Upper Tropospheric and Lower Stratospheric Ozone

Science.gov (United States)

Xia, Yan; Huang, Yi; Hu, Yongyun

2018-01-01

The global warming simulations of the general circulation models (GCMs) are generally performed with different ozone prescriptions. We find that the differences in ozone distribution, especially in the upper tropospheric and lower stratospheric (UTLS) region, account for important model discrepancies shown in the ozone-only historical experiment of the Coupled Model Intercomparison Project Phase 5 (CMIP5). These discrepancies include global high cloud fraction, stratospheric temperature, and stratospheric water vapor. Through a set of experiments conducted by an atmospheric GCM with contrasting UTLS ozone prescriptions, we verify that UTLS ozone not only directly radiatively heats the UTLS region and cools the upper parts of the stratosphere but also strongly influences the high clouds due to its impact on relative humidity and static stability in the UTLS region and the stratospheric water vapor due to its impact on the tropical tropopause temperature. These consequences strongly affect the global mean effective radiative forcing of ozone, as noted in previous studies. Our findings suggest that special attention should be paid to the UTLS ozone when evaluating the climate effects of ozone depletion in the 20th century and recovery in the 21st century. UTLS ozone difference may also be important for understanding the intermodel discrepancy in the climate projections of the CMIP6 GCMs in which either prescribed or interactive ozone is used.

Reducing the negative vocal effects of superficial laryngeal dehydration with humidification.

Science.gov (United States)

Levendoski, Elizabeth Erickson; Sundarrajan, Anusha; Sivasankar, M Preeti

2014-07-01

Environmental humidification is a simple, cost-effective method believed to reduce superficial laryngeal drying. This study sought to validate this belief by investigating whether humidification treatment would reduce the negative effects of superficial laryngeal dehydration on phonation threshold pressure (PTP). Phonation threshold pressure data analysis may be vulnerable to bias because of lack of investigator blinding. Consequently, this study investigated the extent of PTP analysis reliability between unblinded and blinded investigators. Healthy male and female adults were assigned to a vocal fatigue (n = 20) or control group (n = 20) based on their responses to a questionnaire. PTP was assessed after 2 hours of mouth breathing in low humidity (dehydration challenge), following a 5-minute break in ambient humidity, and after 2 hours of mouth breathing in high humidity (humidification). PTP significantly increased following the laryngeal dehydration challenge. After humidification, PTP returned toward baseline. These effects were observed in both subject groups. PTP measurements were highly correlated between the unblinded and blinded investigator. Humidification may be an effective approach to decrease the detrimental voice effects of superficial laryngeal dehydration. These data lay the foundation for future investigations aimed at preventing and treating the negative voice changes associated with chronic, surface laryngeal drying.

An upper tropospheric ‘ozone river’ from Africa to India during the 2008 Asian post-monsoon season

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Flore Tocquer

2015-03-01

Full Text Available We have used ozone data from the Infrared Atmospheric Sounding Interferometer to follow an event of ozone-enriched air-masses in the upper troposphere from eastern Africa to northern India. The ozone transport (hereafter called ‘ozone river’ or O3R occurred during the Asian post-monsoon season in 2008 and was associated with Rossby wave propagation. The persistence of the O3R in a narrow channel was confirmed by MOZAIC airborne data over the northwestern Indian coast. The regions of origin of the O3R were identified by a transport analysis based on the Lagrangian model FLEXPART. The Lagrangian simulations combined with potential vorticity fields indicate that stratospheric intrusions are not likely to be the most important contributor to the observed O3 enhancements. A high-resolution Eulerian model, Meso-NH, with tagged tracers was used to discriminate between African biomass burning, lightnings and Indian anthropogenic pollution as potential sources of precursors for the O3R. Lightning NOx emissions, associated with convective clouds over Africa, were found to be the principal contributor to the ozone enhancement over the Indian Ocean taking advantage of a northeastward jet. This case study illustrates African lightning emissions as an important source for enhanced O3 in the upper troposphere over the Indian Ocean region during the post-monsoon season.

Reactive Nitrogen, Ozone and Ozone Production in the Arctic Troposphere and the Impact of Stratosphere-Troposphere Exchange

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Liang, Q.; Rodriquez, J. M.; Douglass, A. R.; Crawford, J. H.; Apel, E.; Bian, H.; Blake, D. R.; Brune, W.; Chin, M.; Colarco, P. R.;

A new prototype of an electronic jet-ventilator and its humidification system

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Kraincuk, Paul; Kepka, Anton; Ihra, Gerald; Schabernig, Christa; Aloy, Alexander

1999-01-01

Background: Adequate humidification in long-term jet ventilation is a critical aspect in terms of clinical safety. Aim: To assess a prototype of an electronic jet-ventilator and its humidification system. Methods: Forty patients with respiratory insufficiency were randomly allocated to one of four groups. The criterion for inclusion in this study was respiratory insufficiency exhibiting a Murray score above 2. The four groups of patients were ventilated with three different respirators and four different humidification systems. Patients in groups A and B received superimposed high-frequency jet ventilation (SHFJV) by an electronic jet-ventilator either with (group A) or without (group B) an additional humidification system. Patients in group C received high-frequency percussive ventilation (HFPV) by a pneumatic high-frequency respirator, using a hot water humidifier for warming and moistening the inspiration gas. Patients in group D received conventional mechanical ventilation using a standard intensive care unit respirator with a standard humidification system. SHFJV and HFPV were used for a period of 100 h (4days). Results: A significantly low inspiration gas temperature was noted in patients in group B, initially (27.2 ± 2.5°C) and after 2 days (28.0 ± 1.6°C) (P humidification associated with jet ventilation can be fully prevented by using this new jet-ventilator. These data were sustained by nondeteriorating MIS values at the end of the 4-day study period in groups A, C and D. PMID:11056732

Active humidification with Boussignac CPAP: in vitro study of a new method.

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Alonso-Iñigo, José M; Almela, Amadeo; Albert, Alejandro; Carratalá, José M; Fas, María J

2013-04-01

To carry out an in vitro study of Boussignac CPAP valve performance with a new humidification method, using a heated humidifier. Two heated humidifiers were evaluated: Fisher & Paykel MR850, and Covidien Kendall Aerodyne 2000. Baseline measurements were taken in all experimental conditions without humidification. The Boussignac valve was adapted to the input of the humidification chamber. The system was connected to a test lung to assess the degree of pressurization. Hygrometric and pressure measurements were performed with the following gas flows: 10, 20, 30 and 40 L/min. The mean values of pressure generated by the Boussignac valve were 1.99 ± 0.02, 6.97 ± 0.05, 16.61 ± 0.08 and 21.24 ± 0.08 cm H2O, 10, 20, 30 and 40 L/min, respectively, no differences being detected between study groups. Overall absolute humidity was significantly greater with a heated humidifier than without humidification (range 40.01 ± 0.57-25.46 ± 0.49 compared to 0.16 ± 0.13 mgH2O/L, P humidification yielded humidity values above 25 mg H2O/L regardless of the heated humidifier and flow used. Pressurization values remained constant in each experimental situation and were not influenced by adding humidification. These data open up the possibility of using Boussignac CPAP on different types of patients, with different interfaces and for long periods of time.

Influence of mouth opening on oropharyngeal humidification and temperature in a bench model of neonatal continuous positive airway pressure.

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Fischer, Hendrik S; Ullrich, Tim L; Bührer, Christoph; Czernik, Christoph; Schmalisch, Gerd

2017-02-01

Clinical studies show that non-invasive respiratory support by continuous positive airway pressure (CPAP) affects gas conditioning in the upper airways, especially in the presence of mouth leaks. Using a new bench model of neonatal CPAP, we investigated the influence of mouth opening on oropharyngeal temperature and humidity. The model features the insertion of a heated humidifier between an active model lung and an oropharyngeal head model to simulate the recurrent expiration of heated, humidified air. During unsupported breathing, physiological temperature and humidity were attained inside the model oropharynx, and mouth opening had no significant effect on oropharyngeal temperature and humidity. During binasal CPAP, the impact of mouth opening was investigated using three different scenarios: no conditioning in the CPAP circuit, heating only, and heated humidification. Mouth opening had a strong negative impact on oropharyngeal humidification in all tested scenarios, but heated humidification in the CPAP circuit maintained clinically acceptable humidity levels regardless of closed or open mouths. The model can be used to test new equipment for use with CPAP, and to investigate the effects of other methods of non-invasive respiratory support on gas conditioning in the presence of leaks. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

Observations of peroxyacetyl nitrate (PAN) in the upper troposphere by the Atmospheric Chemistry Experiment-Fourier Transform Spectrometer (ACE-FTS)

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Tereszchuk, K. A.; Moore, D. P.; Harrison, J. J.; Boone, C. D.; Park, M.; Remedios, J. J.; Randel, W. J.; Bernath, P. F.

2013-06-01

Peroxyacetyl nitrate (CH3CO·O2NO2, abbreviated as PAN) is a trace molecular species present in the troposphere and lower stratosphere due primarily to pollution from fuel combustion and the pyrogenic outflows from biomass burning. In the lower troposphere, PAN has a relatively short lifetime and is principally destroyed within a few hours through thermolysis, but it can act as a reservoir and carrier of NOx in the colder temperatures of the upper troposphere, where UV photolysis becomes the dominant loss mechanism. Pyroconvective updrafts from large biomass burning events can inject PAN into the upper troposphere and lower stratosphere (UTLS), providing a means for the long-range transport of NOx. Given the extended lifetimes at these higher altitudes, PAN is readily detectable via satellite remote sensing. A new PAN data product is now available for the Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS) version 3.0 data set. We report observations of PAN in boreal biomass burning plumes recorded during the BORTAS (quantifying the impact of BOReal forest fires on Tropospheric oxidants over the Atlantic using Aircraft and Satellites) campaign (12 July to 3 August 2011). The retrieval method employed by incorporating laboratory-recorded absorption cross sections into version 3.0 of the ACE-FTS forward model and retrieval software is described in full detail. The estimated detection limit for ACE-FTS PAN is 5 pptv, and the total systematic error contribution to the ACE-FTS PAN retrieval is ~ 16%. The retrieved volume mixing ratio (VMR) profiles are compared to coincident measurements made by the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) instrument on the European Space Agency (ESA) Environmental Satellite (ENVISAT). The MIPAS measurements demonstrated good agreement with the ACE-FTS VMR profiles for PAN, where the measured VMR values are well within the associated measurement errors for both instruments and comparative

Energy-Saving Benefits of Adiabatic Humidification in the Air Conditioning Systems of Semiconductor Cleanrooms

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Min-Suk Jo

2017-11-01

Full Text Available This paper aimed to evaluate the applicability of adiabatic humidification in the heating, ventilation, and air conditioning (HVAC systems of semiconductor cleanrooms. Accurate temperature and humidity control are essential in semiconductor cleanrooms and high energy consumption steam humidification is commonly used. Therefore, we propose an adiabatic humidification system employing a pressurized water atomizer to reduce the energy consumption. The annual energy consumption of three different HVAC systems were analyzed to evaluate the applicability of adiabatic humidification. The studied cases were as follows: (1 CASE 1: a make-up air unit (MAU with a steam humidifier, a dry cooling coil (DCC, and a fan filter unit (FFU; (2 CASE 2: a MAU with the pressurized water atomizer, a DCC, and a FFU; and (3 CASE 3: a MAU, a DCC, and a FFU, and the pressurized water atomizer installed in the return duct. The energy saving potential of adiabatic humidification over steam humidification has been proved, with savings of 8% and 23% in CASE 2 and CASE 3 compared to CASE 1, respectively. Furthermore, the pressurized water atomizer installed in the return duct exhibits greater energy saving effect than when installed in the MAU.

Observations of peroxyacetyl nitrate (PAN) in the upper troposphere by the Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS)

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Tereszchuk, K. A.; Moore, D. P.; Harrison, J. J.; Boone, C. D.; Park, M.; Remedios, J. J.; Randel, W. J.; Bernath, P. F.

2013-01-01

Peroxyacetyl nitrate (CH3CO·O2NO2, abbreviated as PAN) is a trace molecular species present in the troposphere and lower stratosphere due primarily to pollution from fuel combustion and the pyrogenic outflows from biomass burning. In the lower troposphere, PAN has a relatively short life-time and is principally destroyed within a few hours through thermolysis, but it can act as a reservoir and carrier of NOx in the colder temperatures of the upper troposphere where UV photolysis becomes the dominant loss mechanism. Pyroconvective updrafts from large biomass burning events can inject PAN into the upper troposphere and lower stratosphere (UTLS), providing a means for the long-range transport of NOx. Given the extended lifetimes at these higher altitudes, PAN is readily detectable via satellite remote sensing. A new PAN data product is now available for the Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS) Version 3.0 data set. We report measurements of PAN in Boreal biomass burning plumes recorded during the Quantifying the impact of BOReal forest fires on Tropospheric oxidants over the Atlantic using Aircraft and Satellites (BORTAS) campaign. The retrieval method employed and errors analysis are described in full detail. The retrieved volume mixing ratio (VMR) profiles are compared to coincident measurements made by the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) instrument on the European Space Agency (ESA) ENVIronmental SATellite (ENVISAT). Three ACE-FTS occultations containing measurements of Boreal biomass burning outflows, recorded during BORTAS, were identified as having coincident measurements with MIPAS. In each case, the MIPAS measurements demonstrated good agreement with the ACE-FTS VMR profiles for PAN. The ACE-FTS PAN data set is used to obtain zonal mean distributions of seasonal averages from ~5 to 20 km. A strong seasonality is clearly observed for PAN concentrations in the global UTLS. Since the

[Effects of two different methods for airway humidification for patients with tracheostomy: a Meta-analysis].

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Wang, Jing; Pi, Hongying

2016-01-01

To evaluate the effects of two different kinds of airway humidification for tracheostomy patients, and to provide their relevant clinical effect and suggestions for their use. Online databases, including PubMed, EMBASE, JBI evidence-based nursing center library, the Cochrane Library, and Chinese databases (CNKI, Wanfang database, VIP, CBM) were searched systematically up to March 2015. Randomized controlled trials (RCTs) were considered eligible for inclusion if the following criteria were met: no history of respiratory tract infection; satisfactory nutritional status; tracheotomy performed; 18 years older. Two different humidification methods were used. Continuous airway humidification was used in the experiment group, while intermittent airway humidification was used in the control group. Two qualified reviewers reviewed the original articles, evaluating the quality of articles, and data were extracted independently. The enrolled RCTs were analyzed by Meta-analysis. A total of nine RCTs were included, containing 631 cases, among them 316 cases in expertment group, and 315 cases in control group. Continuous airway humidification was shown to be able to reduce the incidence of irritable cough [odds ratio (OR) = 0.20, 95% confidence interval (95%CI) = 0.12-0.34, P humidification for tracheostomy patients. Because the number of including articles was relative small, and the quality of some articles was poor, it is impossible to draw a reliable conclusion that continuous airway humidification could lower the incidence of complications for patients undergone tracheostomy.

Mask humidity during CPAP: influence of ambient temperature, heated humidification and heated tubing.

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Nilius, Georg; Domanski, Ulrike; Schroeder, Maik; Woehrle, Holger; Graml, Andrea; Franke, Karl-Josef

2018-01-01

Mucosal drying during continuous positive airway pressure (CPAP) therapy is problematic for many patients. This study assessed the influence of ambient relative humidity (rH) and air temperature (T) in winter and summer on mask humidity during CPAP, with and without mask leak, and with or without heated humidification ± heated tubing. CPAP (8 and 12 cmH 2 O) without humidification (no humidity [nH]), with heated humidification controlled by ambient temperature and humidity (heated humidity [HH]) and HH plus heated tubing climate line (CL), with and without leakage, were compared in 18 subjects with OSA during summer and winter. The absolute humidity (aH) and the T inside the mask during CPAP were significantly lower in winter versus summer under all applied conditions. Overall, absolute humidity differences between summer and winter were statistically significant in both HH and CL vs. nH ( p humidification or with standard HH. Clinically-relevant reductions in aH were documented during CPAP given under winter conditions. The addition of heated humidification, using a heated tube to avoid condensation is recommended to increase aH, which could be useful in CPAP users complaining of nose and throat symptoms.

Characteristics of intercontinental transport of tropospheric ozone from Africa to Asia

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Han, Han; Liu, Jane; Yuan, Huiling; Zhuang, Bingliang; Zhu, Ye; Wu, Yue; Yan, Yuhan; Ding, Aijun

2018-03-01

In this study, we characterize the transport of ozone from Africa to Asia through the analysis of the simulations of a global chemical transport model, GEOS-Chem, from 1987 to 2006. The receptor region Asia is defined within 5-60° N and 60-145° E, while the source region Africa is within 35° S-15° N and 20° W-55° E and within 15-35° N and 20° W-30° E. The ozone generated in the African troposphere from both natural and anthropogenic sources is tracked through tagged ozone simulation. Combining this with analysis of trajectory simulations using the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model, we find that the upper branch of the Hadley cell connects with the subtropical westerlies in the Northern Hemisphere (NH) to form a primary transport pathway from Africa to Asia in the middle and upper troposphere throughout the year. The Somali jet that runs from eastern Africa near the equator to the Indian subcontinent in the lower troposphere is the second pathway that appears only in NH summer. The influence of African ozone mainly appears over Asia south of 40° N. The influence shows strong seasonality, varying with latitude, longitude, and altitude. In the Asian upper troposphere, imported African ozone is largest from March to May around 30° N (12-16 ppbv) and lowest during July-October around 10° N ( ˜ 2 ppbv). In the Asian middle and lower troposphere, imported African ozone peaks in NH winter between 20 and 25° N. Over 5-40° N, the mean fractional contribution of imported African ozone to the overall ozone concentrations in Asia is largest during NH winter in the middle troposphere ( ˜ 18 %) and lowest in NH summer throughout the tropospheric column ( ˜ 6 %). This seasonality mainly results from the collective effects of the ozone precursor emissions in Africa and meteorology and chemistry in Africa, in Asia and along the transport pathways. The seasonal swing of the Hadley circulation and subtropical westerlies along the

Perception of cabin air quality in airline crew related to air humidification, on intercontinental flights.

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Lindgren, T; Norbäck, D; Wieslander, G

2007-06-01

The influence of air humidification in aircraft, on perception of cabin air quality among airline crew (N = 71) was investigated. In-flight investigations were performed in the forward part and in the aft part on eight intercontinental flights with one Boeing 767 individually, equipped with an evaporation humidifier combined with a dehumidifying unit, to reduce accumulation of condensed water in the wall construction. Four flights had the air humidification active when going out, and turned off on the return flight. The four others had the inverse humidification sequence. The sequences were randomized, and double blind. Air humidification increased relative air humidity (RH) by 10% in forward part, and by 3% in aft part of the cabin and in the cockpit. When the humidification device was active, the cabin air was perceived as being less dry (P = 0.008), and fresher (P = 0.002). The mean concentration of viable bacteria (77-108 cfu/m(3)), viable molds (74-84 cfu/m(3)), and respirable particles (1-8 microg/m3) was low, both during humidified and non-humidified flights. On flights with air humidification, there were less particles in the forward part of the aircraft (P = 0.01). In conclusion, RH can be slightly increased by using ceramic evaporation humidifier, without any measurable increase of microorganisms in cabin air. The cabin air quality was perceived as being better with air humidification. PRACTICAL IMPLICATION: Relative air humidity is low (10-20%) during intercontinental flights, and can be increased by using ceramic evaporation humidifier, without any measurable increase of microorganism in cabin air. Air humidification could increase the sensation of better cabin air quality.

Multi-station synthesis of early twentieth century surface atmospheric electricity measurements for upper tropospheric properties

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R. G. Harrison

2007-07-01

Full Text Available The vertical columnar current density in the global atmospheric electrical circuit depends on the local columnar resistance. A simple model for the columnar resistance is suggested, which separates the local boundary layer component from the upper troposphere cosmic ray component, and calculates the boundary layer component from a surface measurement of air conductivity. This theory is shown to provide reasonable agreement with observations. One application of the simple columnar model theory is to provide a basis for the synthesis of surface atmospheric electrical measurements made simultaneously at several European sites. Assuming the ionospheric potential to be common above all the sites, the theoretical air-earth current density present in the absence of a boundary layer columnar resistance can be found by extrapolation. This is denoted the free troposphere limit air-earth current density, J₀. Using early surface data from 1909 when no ionospheric potential data are available for corroboration, J₀ is found to be ~6 pA m⁻², although this is subject to uncertainties in the data and limitations in the theory. Later (1966–1971 European balloon and surface data give J₀=2.4 pA m⁻².

The clinical utility of long-term humidification therapy in chronic airway disease.

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Rea, Harold; McAuley, Sue; Jayaram, Lata; Garrett, Jeffrey; Hockey, Hans; Storey, Louanne; O'Donnell, Glenis; Haru, Lynne; Payton, Matthew; O'Donnell, Kevin

2010-04-01

Persistent airway inflammation with mucus retention in patients with chronic airway disorders such as COPD and bronchiectasis may lead to frequent exacerbations, reduced lung function and poor quality of life. This study investigates if long-term humidification therapy with high flow fully humidified air at 37 degrees C through nasal cannulae can improve these clinical outcomes in this group of patients. 108 patients diagnosed with COPD or bronchiectasis were randomised to daily humidification therapy or usual care for 12 months over which exacerbations were recorded. Lung function, quality of life, exercise capacity, and measures of airway inflammation were also recorded at baseline, 3 and 12 months. Patients on long-term humidification therapy had significantly fewer exacerbation days (18.2 versus 33.5 days; p = 0.045), increased time to first exacerbation (median 52 versus 27 days; p = 0.0495) and reduced exacerbation frequency (2.97/patient/year versus 3.63/patient/year; p = 0.067) compared with usual care. Quality of life scores and lung function improved significantly with humidification therapy compared with usual care at 3 and 12 months. Long-term humidification therapy significantly reduced exacerbation days, increased time to first exacerbation, improved lung function and quality of life in patients with COPD and bronchiectasis. Clinical trial registered with www.actr.org.au; Number ACTRN2605000623695. Copyright 2010 Elsevier Ltd. All rights reserved.

[Effect of airway humidification on lung injury induced by mechanical ventilation].

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Song, Junjie; Jiang, Min; Qi, Guiyan; Xie, Yuying; Wang, Huaiquan; Tian, Yonggang; Qu, Jingdong; Zhang, Xiaoming; Li, Haibo

2014-12-01

To explore the effect of airway humidification on lung injury as a result of mechanical ventilation with different tidal volume (VT). Twenty-four male Japanese white rabbits were randomly divided into four groups: low VT with airway humidification group, high VT with airway humidification group, low VT and high VT group without humidification, with 6 rabbits in each group. Mechanical ventilation was started after intubation and lasted for 6 hours. Low VT denoted 8 mL/kg, while high VT was 16 mL/kg, fraction of inspired oxygen (FiO₂) denoted 0.40, positive end-expiratory pressure (PEEP) was 0. Temperature at Y piece of circuit in airway humidification groups was monitored and controlled at 40 centigrade. Arterial blood gas analysis, including pH value, arterial partial pressure of oxygen (PaO₂), arterial partial pressure of carbon dioxide (PaCO₂), lung mechanics indexes, including peak airway pressure (P(peak)) and airway resistance (Raw), and lung compliance was measured at 0, 2, 4, 6 hours of mechanical ventilation. The levels of tumor necrosis factor-α (TNF-α) and interleukin-8 (IL-8) in plasma and bronchoalveolar lavage fluid (BALF) were determined by enzyme linked immunosorbent assay (ELISA). The animals were sacrificed at the end of mechanical ventilation. The wet to dry (W/D) ratio of lung tissues was calculated. Histopathologic changes in the lung tissueies were observed with microscope, and lung injury score was calculated. Scanning and transmission electron microscopies were used to examine the integrity of the airway cilia and the tracheal epithelium. Compared with low V(T) group, pH value in high V(T) group was significantly increased, PaCO₂was significantly lowered, and no difference in PaO₂was found. P(peak), Raw, and lung compliance were significantly increased during mechanical ventilation. There were no significant differences in blood gas analysis and lung mechanics indexes between low V(T) with airway humidification group and low V

Humidification of inspired oxygen is increased with pre-nasal cannula, compared to intranasal cannula.

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Dellweg, Dominic; Wenze, Markus; Hoehn, Ekkehard; Bourgund, Olaf; Haidl, Peter

2013-08-01

Oxygen therapy is usually combined with a humidification device, to prevent mucosal dryness. Depending on the cannula design, oxygen can be administered pre- or intra-nasally (administration of oxygen in front of the nasal ostia vs cannula system inside the nasal vestibulum). The impact of cannula design on intra-nasal humidity, however, has not been investigated to date. First, to develop a system, that samples air from the nasal cavity and analyzes the humidity of these samples. Second, to investigate nasal humidity during pre-nasal and intra-nasal oxygen application, with and without humidification. We first developed and validated a sampling and analysis system to measure humidity from air samples. By means of this system we measured inspiratory air samples from 12 subjects who received nasal oxygen with an intra-nasal and pre-nasal cannula at different flows, with and without humidification. The sampling and analysis system showed good correlation to a standard hygrometer within the tested humidity range (r = 0.99, P humidification (P = .001, P humidification. With the addition of humidification we observed no significant change in humidity at any flow, and independent of pre- or intranasal oxygen administration. Pre-nasal administration of dry oxygen achieves levels of intranasal humidity similar to those achieved by intranasal administration in combination with a bubble through humidifier. Pre-nasal oxygen simplifies application and may reduce therapy cost.

Large-scale upper tropospheric pollution observed by MIPAS HCN and C2H6 global distributions

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Glatthor, N.; von Clarmann, T.; Stiller, G. P.; Funke, B.; Koukouli, M. E.; Fischer, H.; Grabowski, U.; Höpfner, M.; Kellmann, S.; Linden, A.

2009-12-01

We present global upper tropospheric HCN and C2H6 amounts derived from MIPAS/ENVISAT limb emission spectra. HCN and C2H6 are retrieved in the spectral regions 715.5-782.7 cm-1 and 811.5-835.7 cm-1, respectively. The datasets consist of 54 days between September 2003 and March 2004. This period covers the peak and decline of the southern hemispheric biomass burning period and some months thereafter. HCN is a nearly unambiguous tracer of biomass burning with an assumed tropospheric lifetime of several months. Indeed, the most significant feature in the MIPAS HCN dataset is an upper tropospheric plume of enhanced values caused by southern hemispheric biomass burning, which in September and October 2003 extended from tropical South America over Africa, Australia to the Southern Pacific. The spatial extent of this plume agrees well with the MOPITT CO distribution of September 2003. Further there is good agreement with the shapes and mixing ratios of the southern hemispheric HCN and C2H6 fields measured by the ACE experiment between September and November 2005. The MIPAS HCN plume extended from the lowermost observation height of 8 km up to about 16 km altitude, with maximum values of 500-600 pptv in October 2003. It was still clearly visible in December 2003, but had strongly decreased by March 2004, confirming the assumed tropospheric lifetime. The main sources of C2H6 are production and transmission of fossil fuels, followed by biofuel use and biomass burning. The C2H6 distribution also clearly reflected the southern hemispheric biomass burning plume and its seasonal variation, with maximum amounts of 600-700 pptv. Generally there was good spatial overlap between the southern hemispheric distributions of both pollution tracers, except for the region between Peru and the mid-Pacific. Here C2H6was considerably enhanced, whereas the HCN amounts were low. Backward trajectory calculations suggested that industrial pollution was responsible for the elevated C2H6

Large-scale upper tropospheric pollution observed by MIPAS HCN and C2H6 global distributions

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A. Linden

2009-12-01

Full Text Available We present global upper tropospheric HCN and C2H6 amounts derived from MIPAS/ENVISAT limb emission spectra. HCN and C2H6 are retrieved in the spectral regions 715.5–782.7 cm−1 and 811.5–835.7 cm−1, respectively. The datasets consist of 54 days between September 2003 and March 2004. This period covers the peak and decline of the southern hemispheric biomass burning period and some months thereafter. HCN is a nearly unambiguous tracer of biomass burning with an assumed tropospheric lifetime of several months. Indeed, the most significant feature in the MIPAS HCN dataset is an upper tropospheric plume of enhanced values caused by southern hemispheric biomass burning, which in September and October 2003 extended from tropical South America over Africa, Australia to the Southern Pacific. The spatial extent of this plume agrees well with the MOPITT CO distribution of September 2003. Further there is good agreement with the shapes and mixing ratios of the southern hemispheric HCN and C2H6 fields measured by the ACE experiment between September and November 2005. The MIPAS HCN plume extended from the lowermost observation height of 8 km up to about 16 km altitude, with maximum values of 500–600 pptv in October 2003. It was still clearly visible in December 2003, but had strongly decreased by March 2004, confirming the assumed tropospheric lifetime. The main sources of C2H6 are production and transmission of fossil fuels, followed by biofuel use and biomass burning. The C2H6 distribution also clearly reflected the southern hemispheric biomass burning plume and its seasonal variation, with maximum amounts of 600–700 pptv. Generally there was good spatial overlap between the southern hemispheric distributions of both pollution tracers, except for the region between Peru and the mid-Pacific. Here C2H6was considerably enhanced, whereas the HCN amounts were low. Backward trajectory calculations suggested that industrial pollution was responsible

Water vapour and ozone profiles in the midlatitude upper troposphere

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G. Vaughan

2005-01-01

Full Text Available We present an investigation of upper tropospheric humidity profiles measured with a standard radiosonde, the Vaisala RS80-A, and a commercial frost-point hygrometer, the Snow White. Modifications to the Snow White, to enable the mirror reflectivity and Peltier cooling current to be monitored during flight, were found to be necessary to determine when the instrument was functioning correctly; a further modification to prevent hydrometeors entering the inlet was also implemented. From 23 combined flights of an ozonesonde, radiosonde and Snow White between September 2001 and July 2002, clear agreement was found between the two humidity sensors, with a mean difference of <2% in relative humidity from 2 to 10km, and 2.2% between 10 and 13km. This agreement required a correction to the radiosonde humidity, as described by Miloshevich et al. (2001. Using this result, the dataset of 324 ozonesonde/RS80-A profiles measured from Aberystwyth between 1991 and 2002 was examined to derive statistics for the distribution of water vapour and ozone. Supersaturation with respect to ice was frequently seen at the higher levels - 24% of the time in winter between 8 and 10km. The fairly uniform distribution of relative humidity persisted to 120% in winter, but decreased rapidly above 100% in summer.

Heated humidification versus heat and moisture exchangers for ventilated adults and children.

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Kelly, Margaret; Gillies, Donna; Todd, David A; Lockwood, Catherine

2010-10-01

Humidification by artificial means must be provided when the upper airway is bypassed during mechanical ventilation. Heated humidification (HH) and heat and moisture exchangers (HMEs) are the most commonly used types of artificial humidification in this situation. To determine whether HHs or HMES are more effective in preventing mortality and other complications in people who are mechanically ventilated. We searched the Cochrane Central Register of Controlled Trials (The Cochrane Library 2010, Issue 4) and MEDLINE, EMBASE and CINAHL (January, 2010) to identify relevant randomized controlled trials. We included randomized controlled trials comparing HMEs to HHs in mechanically ventilated adults and children. We included randomized crossover studies. We assessed the quality of each study and extracted the relevant data. Where appropriate, results from relevant studies were meta-analyzed for individual outcomes. We included 33 trials with 2833 participants; 25 studies were parallel group design (n = 2710) and 8 crossover design (n = 123). Only 3 included studies reported data for infants or children. There was no overall effect on artificial airway occlusion, mortality, pneumonia, or respiratory complications; however, the PaCO(2) and minute ventilation were increased when HMEs were compared to HHs and body temperature was lower. The cost of HMEs was lower in all studies that reported this outcome. There was some evidence that hydrophobic HMEs may reduce the risk of pneumonia and that blockages of artificial airways may be increased with the use of HMEs in certain subgroups of patients. There is little evidence of an overall difference between HMEs and HHs. However, hydrophobic HMEs may reduce the risk of pneumonia and the use of an HMEs may increase artificial airway occlusion in certain subgroups of patients. Therefore, HMEs may not be suitable for patients with limited respiratory reserve or prone to airway blockage. Further research is needed relating to

Particulate sulfur in the upper troposphere and lowermost stratosphere – sources and climate forcing

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B. G. Martinsson

2017-09-01

Full Text Available This study is based on fine-mode aerosol samples collected in the upper troposphere (UT and the lowermost stratosphere (LMS of the Northern Hemisphere extratropics during monthly intercontinental flights at 8.8–12 km altitude of the IAGOS-CARIBIC platform in the time period 1999–2014. The samples were analyzed for a large number of chemical elements using the accelerator-based methods PIXE (particle-induced X-ray emission and PESA (particle elastic scattering analysis. Here the particulate sulfur concentrations, obtained by PIXE analysis, are investigated. In addition, the satellite-borne lidar aboard CALIPSO is used to study the stratospheric aerosol load. A steep gradient in particulate sulfur concentration extends several kilometers into the LMS, as a result of increasing dilution towards the tropopause of stratospheric, particulate sulfur-rich air. The stratospheric air is diluted with tropospheric air, forming the extratropical transition layer (ExTL. Observed concentrations are related to the distance to the dynamical tropopause. A linear regression methodology handled seasonal variation and impact from volcanism. This was used to convert each data point into stand-alone estimates of a concentration profile and column concentration of particulate sulfur in a 3 km altitude band above the tropopause. We find distinct responses to volcanic eruptions, and that this layer in the LMS has a significant contribution to the stratospheric aerosol optical depth and thus to its radiative forcing. Further, the origin of UT particulate sulfur shows strong seasonal variation. We find that tropospheric sources dominate during the fall as a result of downward transport of the Asian tropopause aerosol layer (ATAL formed in the Asian monsoon, whereas transport down from the Junge layer is the main source of UT particulate sulfur in the first half of the year. In this latter part of the year, the stratosphere is the clearly dominating source of

Numerical simulation of humidification and heating during inspiration within an adult nose.

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Sommer, F; Kroger, R; Lindemann, J

2012-06-01

The temperature of inhaled air is highly relevant for the humidification process. Narrow anatomical conditions limit possibilities for in vivo measurements. Numerical simulations offer a great potential to examine the function of the human nose. In the present study, the nasal humidification of inhaled air was simulated simultaneously with temperature distribution during a respiratory cycle. A realistic nose model based on a multislice CT scan was created. The simulation was performed by the Software Fluent(r). Boundary conditions were based on previous in vivo measurements. Inhaled air had a temperature of 20(deg)C and relative humidity of 30%. The wall temperature was assumed to be variable from 34(deg)C to 30(deg)C with constant humidity saturation of 100% during the respiratory cycle. A substantial increase in temperature and humidity can be observed after passing the nasal valve area. Areas with high speed air flow, e.g. the space around the turbinates, show an intensive humidification and heating potential. Inspired air reaches 95% humidity and 28(deg)C within the nasopharynx. The human nose features an enormous humidification and heating capability. Warming and humidification are dependent on each other and show a similar spacial pattern. Concerning the climatisation function, the middle turbinate is of high importance. In contrast to in vivo measurements, numerical simulations can explore the impact of airflow distribution on nasal air conditioning. They are an effective method to investigate nasal pathologies and impacts of surgical procedures.

[Humidification assessment of four heat and moisture exchanger filters according to ISO 9360: 2000 standard].

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Lannoy, D; Décaudin, B; Resibois, J-P; Barrier, F; Wierre, L; Horrent, S; Batt, C; Moulront, S; Odou, P

2008-02-01

This work consisted of the assessment of humidification parameters and flow resistance for different heat and moisture exchanger filters (HMEF) used in intensive care unit. Four electrostatic HMEF were assessed: Hygrobac S (Tyco); Humidvent compact S (Teleflex); Hygrovent S/HME (Medisize-Dräger); Clear-Therm+HMEF (Intersurgical). Humidification parameters (loss of water weight, average absolute moisture [AAM], absolute variation of moisture) have been evaluated on a bench-test in conformity with the ISO 9360: 2000 standard, for 24h with the following ventilatory settings: tidal volume at 500 ml, respiratory rate at 15 c/min, and inspiration/expiration ratio at 1:1. The flow resistance of HMEFs assessed using the pressure drop method was measured before and after 24h of humidification for three increasing air flows of 30, 60, and 90 l/min. All the HMEFs allowed satisfactory level of humidification exceeding 30 mgH(2)O/l. The less powerful remained the Clear-Therm. Concerning HMEFs flow resistance, results showed a pressure drop slightly more important for the Hygrobac S filter as compared with other filters. This test showed differences between the HMEFs for both humidification and resistance parameters. When compared to the new version of the standards, HMEFs demonstrated their reliability. However, evolution of humidification and flow resistance characteristics over 24h showed a structural degradation of HMEFs, limiting their use over a longer period.

Heated humidification improves clinical outcomes, compared to a heat and moisture exchanger in children with tracheostomies.

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McNamara, David G; Asher, M Innes; Rubin, Bruce K; Stewart, Alistair; Byrnes, Catherine A

2014-01-01

The upper airway humidifies and warms inspired gases before they reach the trachea, a process bypassed by the insertion of a tracheostomy, necessitating humidification of inspired gases. The optimal method of humidification is not known. We conducted a short-term 20-hour study and a long-term 10-week randomized crossover study comparing a heated humidifier (HH) to a heat and moisture exchanger (HME) in children with established tracheostomies. Subjects were assessed for clinical events, clinical examination findings, airway cytokine levels, and airway secretion viscoelasticity. For the short-term study, 15 children were recruited; for the long-term study, 14 children were recruited. Children using the HH had decreased respiratory examination score (P < .001) but no change in clinical events over the short term. There was a decrease in acute clinical events (P = .008) in the long-term study. No differences were found in airway secretion viscoelasticity results or cytokine levels in either study, but these sample numbers were limited. Over 20 hours use, HH, compared to HME, improved work of breathing. Over a longer 10 week treatment period HH resulted in decreased adverse clinical events.

Concentration variations of the tropospheric carbon dioxide over the Antarctic region

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Shohei Murayama

1997-03-01

Full Text Available Aircraft measurements of the atmospheric CO_2 concentration have been made over Syowa Station, Antarctica since 1983. The minimum concentration of the average seasonal CO_2 cycle appears in March throughout the troposphere, while the maximum concentration occurs in mid-August in the upper troposphere and in late September in the middle and lower troposphere. The peak-to-peak amplitude of the seasonal cycle decreases with height. The CO_2 concentration increases with height during most of the year; however, this height dependency is larger from summer to early winter than in the remaining seasons. The average concentration difference between the upper troposphere and the ground surface is about 0.3ppmv. From comparisons with the results of the ground-based and aircraft measurements at southern middle and high latitudes and trajectory analysis, it is hypothesized that the seasonal cycle of height-dependent atmospheric transport processes could influence the seasonal cycle and the vertical distribution of the CO_2 concentration over Syowa Station.

A hybrid desalination system using humidification-dehumidification and solar stills integrated with evacuated solar water heater

International Nuclear Information System (INIS)

Sharshir, S.W.; Peng, Guilong; Yang, Nuo; Eltawil, Mohamed A.; Ali, Mohamed Kamal Ahmed; Kabeel, A.E.

2016-01-01

Highlights: • Evacuated solar water heater integrated with humidification-dehumidification system. • Reuse of warm water drained from humidification-dehumidification to feed solar stills. • The thermal performance of hybrid system is increased by 50% and maximum yield is 63.3 kg/day. • The estimated price of the freshwater produced from the hybrid system is $0.034/L. - Abstract: This paper offers a hybrid solar desalination system comprising a humidification-dehumidification and four solar stills. The developed hybrid desalination system reuses the drain warm water from humidification-dehumidification to feed solar stills to stop the massive warm water loss during desalination. Reusing the drain warm water increases the gain output ratio of the system by 50% and also increased the efficiency of single solar still to about 90%. Furthermore, the production of a single solar still as a part of the hybrid system was more than that of the conventional one by approximately 200%. The daily water production of the conventional one, single solar still, four solar still, humidification- dehumidification and hybrid system were 3.2, 10.5, 42, 24.3 and 66.3 kg/day, respectively. Furthermore, the cost per unit liter of distillate from conventional one, humidification- dehumidification and hybrid system were around $0.049, $0.058 and $0.034, respectively.

Humidification and perceived indoor air quality in the office environment.

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Reinikainen, L M; Aunela-Tapola, L; Jaakkola, J J

1997-01-01

OBJECTIVE: To evaluate the effect of humidification on the odour, acceptability, and stuffiness of indoor air. METHODS: In a six period cross over trial at the Pasila Office Center, Helsinki, the air of two wings of the building in turn were ventilated with air of 30%-40% humidity. A third wing served as a non-humidified control area. The quality of indoor air was assessed weekly by a panel containing 18 to 23 members. The intraindividual differences in the ratings for odour, stuffiness, and acceptability between humidified and non-humidified wings were used to assess the effect of humidification. The roles of sex, current smoking, and age as potential effect modifiers were assessed by comparing the mean intraindividual differences in ratings between the groups. RESULTS: Humidified air was found to be more odorous and stuffy (paired t test P = 0.0001) and less acceptable than the non-humidified air (McNemar's test P humidification decreases the perceived air quality. This effect is strongest in women and young subjects. PMID:9196454

Experimental analysis of humidification process by air passing through seawater

International Nuclear Information System (INIS)

El-Agouz, S.A.; Abugderah, M.

2008-01-01

An experimental investigation of humidification process by air passing through seawater is presented. The main objective of this work was to determine the humid air behaviour through single-stage of heating-humidifying processes. This experimental work studied the influence of the operating conditions such as the water temperature, the headwater difference, the air velocity and the inlet air temperature to evaporator chamber on the vapour content difference and humidification efficiency. Two cases of different inlet conditions of ambient and heated air cases are studied. The experimental results show that, the vapour content difference and the humidification efficiency of the system is strongly affected by the saline water temperature in the evaporator chamber, headwater difference and the air velocity. The inlet air temperature to evaporator chamber variation was found to have a small affect on the vapour content difference. The obtained maximum vapour content difference of the air was about 222 gr w /kg a at 75 deg. C for water and air. The obtained vapour content is high compared to that obtained in literature for single-stage and very similar for multi-stage

Remote sensed and in situ constraints on processes affecting tropical tropospheric ozone

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B. Sauvage

2007-01-01

Full Text Available We use a global chemical transport model (GEOS-Chem to evaluate the consistency of satellite measurements of lightning flashes and ozone precursors with in situ measurements of tropical tropospheric ozone. The measurements are tropospheric O3, NO2, and HCHO columns from the GOME satellite instrument, lightning flashes from the OTD and LIS satellite instruments, profiles of O3, CO, and relative humidity from the MOZAIC aircraft program, and profiles of O3 from the SHADOZ ozonesonde network. We interpret these multiple data sources with our model to better understand what controls tropical tropospheric ozone. Tropical tropospheric ozone is mainly affected by lightning NOx and convection in the upper troposphere and by surface emissions in the lower troposphere. Scaling the spatial distribution of lightning in the model to the observed flashes improves the simulation of O3 in the upper troposphere by 5–20 ppbv versus in situ observations and by 1–4 Dobson Units versus GOME retrievals of tropospheric O3 columns. A lightning source strength of 6±2 Tg N/yr best represents in situ observations from aircraft and ozonesonde. Tropospheric NO2 and HCHO columns from GOME are applied to provide top-down constraints on emission inventories of NOx (biomass burning and soils and VOCs (biomass burning. The top-down biomass burning inventory is larger than the bottom-up inventory by a factor of 2 for HCHO and alkenes, and by a factor of 2.6 for NOx over northern equatorial Africa. These emissions increase lower tropospheric O3 by 5–20 ppbv, improving the simulation versus aircraft observations, and by 4 Dobson Units versus GOME observations of tropospheric O3 columns. Emission factors in the a posteriori inventory are more consistent with a recent compilation from in situ measurements. The ozone simulation using two different dynamical schemes (GEOS-3 and GEOS-4 is evaluated versus observations; GEOS-4 better represents O3 observations by 5–15 ppbv

Humidification of unwrapped chilled meat on retail display using an ultrasonic fogging system.

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Brown, Tim; Corry, Janet E L; Evans, Judith A

2007-12-01

The effects of an ultrasonic humidification system on unwrapped meat in a chilled retail display cabinet were assessed. Humidification raised the relative humidity of the cabinet air from a mean of 76.7% to just below saturation at 98.8%. This reduced the mean evaporative weight loss from whole samples of meat after 14h from 1.68% to 0.62% of their initial weight. The rate of deterioration in the appearance of the meat due to dehydration was reduced to the extent that while the unhumidified trial was terminated after 14h because all samples were judged to be unacceptable, the humidified trial was continued for 24h without any major changes in appearance. Levels of presumptive pseudomonas bacteria were relatively high in water samples taken from the humidification system and defrost water during the humidified trial, but Legionella spp. were not isolated. Significant increases in the numbers of bacteria on the meat during either trial were only found in one case, that of humidified minced beef. However, some of the samples had high counts even before display, and this may have masked any effect due to humidification. Differences in levels of air-borne contamination were small and inconsistent. Air temperatures were raised by humidification by between 1 and 2°C and this was reflected in similarly raised product temperatures. Temperatures of air leaving the evaporator indicated that this was due to icing of the evaporator in the periods leading up to defrosts.

Design and control of the oxygen partial pressure of UO2 in TGA using the humidification system

International Nuclear Information System (INIS)

Lee, S.; Knight, T.W.; Roberts, E.

2015-01-01

Highlights: • We focus on measurement of oxygen partial pressure and change of O/M ratio under specific conditions produced by the humidification system. • This shows that the humidification system is stable, accurate, and reliable enough to be used for experiments of the oxygen partial pressure measurement for the oxide fuels. • The humidification system has benefits of easy control and flexibility for producing various oxygen partial pressures with fixed hydrogen gas flow rate. - Abstract: The oxygen to uranium (O/U) ratio of UO 2±x is determined by the oxygen content of the sample and is affected by oxygen partial pressure (pO 2 ) of the surrounding gas. Oxygen partial pressure is controllable by several methods. A common method to produce different oxygen partial pressures is the use of equilibria of different reaction gases. There are two common methods: H 2 O/H 2 reaction and CO 2 /CO reaction. In this work, H 2 O/H 2 reaction using a humidifier was employed and investigated to ensure that this humidification system for oxygen partial pressure is stable and accurate for use in Thermogravimetric Analyzer (TGA) experiments with UO 2 . This approach has the further advantage of flexibility to make a wide range of oxygen partial pressure with fixed hydrogen gas flow rate only by varying temperature of water in the humidifier. The whole system for experiments was constructed and includes the humidification system, TGA, oxygen analyzer, and gas flow controller. Uranium dioxide (UO 2 ) samples were used for experiments and oxygen partial pressure was measured at the equilibrium state of stoichiometric UO 2.0 . Oxygen partial pressures produced by humidification (wet gas) system were compared to the approach using mixed dry gases (without humidification system) to demonstrate that the humidification system provides for more stable and accurate oxygen partial pressure control. This work provides the design, method, and analysis of a humidification system for

Aerosol characteristics and particle production in the upper troposphere over the Amazon Basin

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Andreae, Meinrat O.; Afchine, Armin; Albrecht, Rachel; Amorim Holanda, Bruna; Artaxo, Paulo; Barbosa, Henrique M. J.; Borrmann, Stephan; Cecchini, Micael A.; Costa, Anja; Dollner, Maximilian; Fütterer, Daniel; Järvinen, Emma; Jurkat, Tina; Klimach, Thomas; Konemann, Tobias; Knote, Christoph; Krämer, Martina; Krisna, Trismono; Machado, Luiz A. T.; Mertes, Stephan; Minikin, Andreas; Pöhlker, Christopher; Pöhlker, Mira L.; Pöschl, Ulrich; Rosenfeld, Daniel; Sauer, Daniel; Schlager, Hans; Schnaiter, Martin; Schneider, Johannes; Schulz, Christiane; Spanu, Antonio; Sperling, Vinicius B.; Voigt, Christiane; Walser, Adrian; Wang, Jian; Weinzierl, Bernadett; Wendisch, Manfred; Ziereis, Helmut

2018-01-01

Airborne observations over the Amazon Basin showed high aerosol particle concentrations in the upper troposphere (UT) between 8 and 15 km altitude, with number densities (normalized to standard temperature and pressure) often exceeding those in the planetary boundary layer (PBL) by 1 or 2 orders of magnitude. The measurements were made during the German-Brazilian cooperative aircraft campaign ACRIDICON-CHUVA, where ACRIDICON stands for Aerosol, Cloud, Precipitation, and Radiation Interactions and Dynamics of Convective Cloud Systems and CHUVA is the acronym for Cloud Processes of the Main Precipitation Systems in Brazil: A Contribution to Cloud Resolving Modeling and to the GPM (global precipitation measurement), on the German High Altitude and Long Range Research Aircraft (HALO). The campaign took place in September-October 2014, with the objective of studying tropical deep convective clouds over the Amazon rainforest and their interactions with atmospheric trace gases, aerosol particles, and atmospheric radiation. Aerosol enhancements were observed consistently on all flights during which the UT was probed, using several aerosol metrics, including condensation nuclei (CN) and cloud condensation nuclei (CCN) number concentrations and chemical species mass concentrations. The UT particles differed sharply in their chemical composition and size distribution from those in the PBL, ruling out convective transport of combustion-derived particles from the boundary layer (BL) as a source. The air in the immediate outflow of deep convective clouds was depleted of aerosol particles, whereas strongly enhanced number concentrations of small particles ( 90 nm) particles in the UT, which consisted mostly of organic matter and nitrate and were very effective CCN. Our findings suggest a conceptual model, where production of new aerosol particles takes place in the continental UT from biogenic volatile organic material brought up by deep convection and converted to condensable

The effect of mouth leak and humidification during nasal non-invasive ventilation.

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Tuggey, Justin M; Delmastro, Monica; Elliott, Mark W

2007-09-01

Poor mask fit and mouth leak are associated with nasal symptoms and poor sleep quality in patients receiving domiciliary non-invasive ventilation (NIV) through a nasal mask. Normal subjects receiving continuous positive airways pressure demonstrate increased nasal resistance following periods of mouth leak. This study explores the effect of mouth leak during pressure-targeted nasal NIV, and whether this results in increased nasal resistance and consequently a reduction in effective ventilatory support. A randomised crossover study of 16 normal subjects was performed on separate days. Comparison was made of the effect of 5 min of mouth leak during daytime nasal NIV with and without heated humidification. Expired tidal volume (V(T)), nasal resistance (R(N)), and patient comfort were measured. Mean change (Delta) in V(T) and R(N) were significantly less following mouth leak with heated humidification compared to the without (DeltaV(T) -36+/-65 ml vs. -88+/-50 ml, phumidification (5.3+/-0.4 vs. 6.2+/-0.4, phumidification. In normal subjects, heated humidification during nasal NIV attenuates the adverse effects of mouth leak on effective tidal volume, nasal resistance and improves overall comfort. Heated humidification should be considered as part of an approach to patients who are troubled with nasal symptoms, once leak has been minimised.

Field Study on Humidification Performance of a Desiccant Air-Conditioning System Combined with a Heat Pump

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Koichi Kawamoto

2016-01-01

Full Text Available A desiccant air-conditioning system was developed as a latent-load-processing air conditioner in a dedicated outdoor air system during the summer. This study investigated the application of this air-conditioning system to humidification during the winter without using make-up water, thereby eliminating the cause of microbial contamination in air-conditioning systems. The experiments were conducted with a system used for summer applications to determine the feasibility of adsorbing vapor from outdoor air and supplying it to an indoor space. The humidification performance, energy efficiency, and operating conditions were examined. Although the conditions were subpar because the experiments were performed with an actual dedicated outdoor air system, the results showed that it is possible to supply air with a minimum humidity ratio of 5.8 g/kg dry air (DA when the humidity ratio of outdoor air ranges from 1.8 to 2.3 g/kg DA. The minimum humidification performance required for a dedicated outdoor air system was achieved by increasing the airflow rate of the moisture-adsorption side to 2–3 times that of the humidification side. In addition, air leaking from the moisture-adsorption side to the humidification side, improving the mechanical structure, such as by the insulation of the moisture-adsorption side, and an efficient operating method were examined for humidification during the winter.

Interrelated variations of O3, CO and deep convection in the tropical/subtropical upper troposphere observed by the Aura Microwave Limb Sounder (MLS during 2004–2011

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L. Froidevaux

2013-01-01

Full Text Available The interrelated geographic and temporal variability seen in more than seven years of tropical and subtropical upper tropospheric (215 hPa ozone, carbon monoxide and cloud ice water content (IWC observations by the Aura Microwave Limb Sounder (MLS are presented. Observed ozone abundances and their variability (geographic and temporal agree to within 10–15 ppbv with records from sonde observations. MLS complements these (and other observations with global coverage and simultaneous measurements of related parameters. Previously-reported phenomena such as the ozone "wave one" feature are clearly seen in the MLS observations, as is a double peak in ozone abundance over tropical East Africa, with enhanced abundances in both May to June and September to November. While repeatable seasonal cycles are seen in many regions, they are often accompanied by significant interannual variability. Ozone seasonal cycles in the southern tropics and subtropics tend to be more distinct (i.e., annually repeatable than in the northern. By contrast, carbon monoxide shows distinct seasonal cycles in many northern subtropical regions, notably from India to the Eastern Pacific. Deep convection (as indicated by large values of IWC is typically associated with reductions in upper tropospheric ozone. Convection over polluted regions is seen to significantly enhance upper tropospheric carbon monoxide. While some regions show statistically significant correlations among ozone, carbon monoxide and IWC, simple correlations fall well short of accounting for the observed variability. The observed interrelated variations and metrics of annual and interannual variability described here represent a new resource for validation of atmospheric chemistry models.

Persistence of Upper-Airway Symptoms During CPAP Compromises Adherence at 1 Year.

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Kreivi, Hanna-Riikka; Maasilta, Paula; Bachour, Adel

2016-05-01

The most common adverse effects of CPAP are related to the upper airways. We evaluated upper-airway symptoms before and after a CPAP trial as well as their effect on CPAP adherence. We also evaluated the effect of humidification added to CPAP therapy on upper-airway symptoms. We followed for 1 y 536 subjects with obstructive sleep apnea scheduled consecutively for CPAP initiation. Subjects completed visual analog questionnaires on nasal stuffiness, rhinorrhea, and mouth dryness (0 = no symptoms, 100 = severe symptoms). Before CPAP initiation, mean nasal stuffiness score was 29.6 ± 24.9, rhinorrhea score was 16.0 ± 21.7, and mouth dryness score was 43.8 ± 33.1. In subjects who quit CPAP treatment before the 1-y follow-up, the increase in rhinorrhea score during CPAP initiation was significant, 5.3 (95% CI 0.5-9.5, P = .02), and in those using CPAP at 1 y, nasal stuffiness score and mouth dryness score decreased significantly during initiation, -5.1 (95% CI -7.9 to -2.4, P CPAP regardless of humidification: change with humidification, -18.1 (95% CI -22.1 to -14.3), P CPAP, whereas its absence induced a significant rise in symptom scores: change in rhinorrhea, 11.5 (95% CI 7.1-16.7), P CPAP does not predict CPAP use at 1 y, whereas CPAP non-users at 1 y had smaller or no alleviation in symptom scores during initiation compared with those who continued CPAP treatment. Copyright © 2016 by Daedalus Enterprises.

Large differences in reanalyses of diabatic heating in the tropical upper troposphere and lower stratosphere

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Wright, J. S.; Fueglistaler, S.

2013-09-01

We present the time mean heat budgets of the tropical upper troposphere (UT) and lower stratosphere (LS) as simulated by five reanalysis models: the Modern-Era Retrospective Analysis for Research and Applications (MERRA), European Reanalysis (ERA-Interim), Climate Forecast System Reanalysis (CFSR), Japanese 25-yr Reanalysis and Japan Meteorological Agency Climate Data Assimilation System (JRA-25/JCDAS), and National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) Reanalysis 1. The simulated diabatic heat budget in the tropical UTLS differs significantly from model to model, with substantial implications for representations of transport and mixing. Large differences are apparent both in the net heat budget and in all comparable individual components, including latent heating, heating due to radiative transfer, and heating due to parameterised vertical mixing. We describe and discuss the most pronounced differences. Discrepancies in latent heating reflect continuing difficulties in representing moist convection in models. Although these discrepancies may be expected, their magnitude is still disturbing. We pay particular attention to discrepancies in radiative heating (which may be surprising given the strength of observational constraints on temperature and tropospheric water vapour) and discrepancies in heating due to turbulent mixing (which have received comparatively little attention). The largest differences in radiative heating in the tropical UTLS are attributable to differences in cloud radiative heating, but important systematic differences are present even in the absence of clouds. Local maxima in heating and cooling due to parameterised turbulent mixing occur in the vicinity of the tropical tropopause.

Humidification during high-frequency oscillation ventilation is affected by ventilator circuit and ventilatory setting.

Science.gov (United States)

Chikata, Yusuke; Imanaka, Hideaki; Onishi, Yoshiaki; Ueta, Masahiko; Nishimura, Masaji

2009-08-01

High-frequency oscillation ventilation (HFOV) is an accepted ventilatory mode for acute respiratory failure in neonates. As conventional mechanical ventilation, inspiratory gas humidification is essential. However, humidification during HFOV has not been clarified. In this bench study, we evaluated humidification during HFOV in the open circumstance of ICU. Our hypothesis is that humidification during HFOV is affected by circuit design and ventilatory settings. We connected a ventilator with HFOV mode to a neonatal lung model that was placed in an infant incubator set at 37 degrees C. We set a heated humidifier (Fisher & Paykel) to obtain 37 degrees C at the chamber outlet and 40 degrees C at the distal temperature probe. We measured absolute humidity and temperature at the Y-piece using a rapid-response hygrometer. We evaluated two types of ventilator circuit: a circuit with inner heating wire and another with embedded heating element. In addition, we evaluated three lengths of the inspiratory limb, three stroke volumes, three frequencies, and three mean airway pressures. The circuit with embedded heating element provided significantly higher absolute humidity and temperature than one with inner heating wire. As an extended tube lacking a heating wire was shorter, absolute humidity and temperature became higher. In the circuit with inner heating wire, absolute humidity and temperature increased as stroke volume increased. Humidification during HFOV is affected by circuit design and ventilatory settings.

Thermodynamic and numerical analysis of intake air humidification ...

Indian Academy of Sciences (India)

Bin Chen

2018-05-14

May 14, 2018 ... ciency while reducing emissions to meet the market requirements. For gasoline ... and the effects of intake air humidification on knock. In this case, this ..... efficient strategy of suppressing knock occurrence of gasoline engines.

Tropospheric ozone annual variation and possible troposphere-stratosphere coupling in the Arctic and Antarctic as derived from ozone soundings at Resolute and Amundsen-Scott stations

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Gruzdev, A.N.; Sitnov, S.A. (Russian Academy of Sciences, Moscow (Russian Federation). Inst. of Atmospheric Physics)

1993-01-01

The tropospheric ozone annual variation in the northern and southern polar regions is analyzed from ozone sounding data obtained at Resolute during a 15-year period and Amundsen-Scott during a 7-year period. The phase of ozone annual variation above Resolute changes (increases) gradually from the stratosphere across the tropopause to the middle troposphere. Unlike this, the phase of the Antarctic ozone annual harmonic has a discontinuity in the layer of the changing tropopause level, so that the annual harmonic in the upper troposphere, lower stratosphere is 4-to-5 months out of phase (earlier) to that above and beneath. Above both the Arctic and Antarctic stations, the ozone mixing ratio and its vertical gradient evolve in a similar manner in the wide layer from the lower stratosphere to the middle troposphere. This likely points out that ozone in this layer is controlled from above. An indication of the stratospheric-tropospheric ozone exchange above Resolute is noted from mid-winter to spring. The analysis of columnar tropospheric ozone changes gives a lower estimate of the cross-tropopause ozone flux up to 5x10[sup 10] mol cm[sup -2] s[sup -1]. Above the South Pole, the cross-tropopause ozone flux is not usually large. There is also some evidence that early in the spring, when the stratospheric ozone 'hole' is developed, the stratospheric-tropospheric exchange conducts the influence of the 'hole' into the upper troposphere, where the integrated ozone destruction is estimated to be 8x10[sup 10] mol cm[sup -2] s[sup -1]. Correlation analysis gives no ozone-tropopause correlation in the Antarctic in winter, while in other seasons as well as during all seasons in the Arctic, there are negative correlation peaks just above the tropopause. (19 refs., 6 figs.).

A modelling study of the impact of cirrus clouds on the moisture budget of the upper troposphere

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S. Fueglistaler

2006-01-01

Full Text Available We present a modelling study of the effect of cirrus clouds on the moisture budget of the layer wherein the cloud formed. Our framework simplifies many aspects of cloud microphysics and collapses the problem of sedimentation onto a 0-dimensional box model, but retains essential feedbacks between saturation mixing ratio, particle growth, and water removal through particle sedimentation. The water budget is described by two coupled first-order differential equations for dimensionless particle number density and saturation point temperature, where the parameters defining the system (layer depth, reference temperature, amplitude and time scale of temperature perturbation and inital particle number density, which may or may not be a function of reference temperature and cooling rate are encapsulated in a single coefficient. This allows us to scale the results to a broad range of atmospheric conditions, and to test sensitivities. Results of the moisture budget calculations are presented for a range of atmospheric conditions (T: 238–205 K; p: 325–180 hPa and a range of time scales τT of the temperature perturbation that induces the cloud formation. The cirrus clouds are found to efficiently remove water for τT longer than a few hours, with longer perturbations (τT≳10 h required at lower temperatures (T≲210 K. Conversely, we find that temperature perturbations of duration order 1 h and less (a typical timescale for e.g., gravity waves do not efficiently dehydrate over most of the upper troposphere. A consequence is that (for particle densities typical of current cirrus clouds the assumption of complete dehydration to the saturation mixing ratio may yield valid predictions for upper tropospheric moisture distributions if it is based on the large scale temperature field, but this assumption is not necessarily valid if it is based on smaller scale temperature fields.

The Vertical Structure of Relative Humidity and Ozone in the Tropical Upper Troposphere: Intercomparisons Among In Situ Observations, A-Train Measurements and Large-Scale Models

Science.gov (United States)

Selkirk, Henry B.; Manyin, Michael; Douglass, Anne R.; Oman, Luke; Pawson, Steven; Ott, Lesley; Benson, Craig; Stolarski, Richard

2010-01-01

In situ measurements in the tropics have shown that in regions of active convection, relative humidity with respect to ice in the upper troposphere is typically close to saturation on average, and supersaturations greater than 20% are not uncommon. Balloon soundings with the cryogenic frost point hygrometer (CFH) at Costa Rica during northern summer, for example, show this tendency to be strongest between 11 and 15.5 km (345-360 K potential temperature, or approximately 250-120 hPa). this is the altitude range of deep convective detrainment. Additionally, simultaneous ozonesonde measurements show that stratospheric air (O3 greater than 150 ppbv) can be found as low as approximately 14 km (350 K/150 hPa). In contrast, results from northern winter show a much drier upper troposphere and little penetration of stratospheric air below the tropopause at 17.5 km (approximately 383 K). We show that these results are consistent with in situ measurements from the Measurement of Ozone and water vapor by Airbus In-service airCraft (MOZAIC) program which samples a wider, though still limited, range of tropical locations. To generalize to the tropics as a whole, we compare our insitu results to data from two A-Train satellite instruments, the Atmospheric Infrared Sounder (AIRS) and the Microwave Limb Sounder (MLS) on the Aqua and Aura satellites respectively. Finally, we examine the vertical structure of water vapor, relative humidity and ozone in the NASA Goddard MERRA analysis, an assimilation dataset, and a new version of the GEOS CCM, a free-running chemistry-climate model. We demonstrate that conditional probability distributions of relative humidity and ozone are a sensitive diagnostic for assessing the representation of deep convection and upper troposphere/lower stratosphere mixing processes in large-scale analyses and climate models.

Carbon monoxide distributions from the upper troposphere to the mesosphere inferred from 4.7 μm non-local thermal equilibrium emissions measured by MIPAS on Envisat

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B. Funke

2009-04-01

Full Text Available We present global distributions of carbon monoxide (CO from the upper troposphere to the mesosphere observed by the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS on Envisat. Vertically resolved volume mixing ratio profiles have been retrieved from 4.7 μm limb emission spectra under consideration of non-local thermodynamic equilibrium. The precision of individual CO profiles is typically 5–30 ppbv (15–40% for altitudes greater than 40 km and lower than 15 km and 30–90% within 15–40 km. Estimated systematic errors are in the order of 8–15%. Below 60 km, the vertical resolution is 4–7 km. The data set which covers 54 days from September 2003 to March 2004 has been derived with an improved retrieval version including (i the retrieval of log(vmr, (ii the consideration of illumination-dependent vibrational population gradients along the instrument's line of sight, and (iii joint-fitted vmr horizontal gradients in latitudinal and longitudinal directions. A detailed analysis of spatially resolved CO distributions during the 2003/2004 Northern Hemisphere major warming event demonstrate the potential of MIPAS CO observations to obtain new information on transport processes during dynamical active episodes, particularly on those acting in the vertical. From the temporal evolution of zonally averaged CO abundances, we derived extraordinary polar winter descent velocities of 1200 m per day inside the recovered polar vortex in January 2004. Middle stratospheric CO abundances show a well established correlation with the chemical source CH₄, particularly in the tropics. In the upper troposphere, a moderate CO decrease from September 2003 to March 2004 was observed. Upper tropospheric CO observations provide a detailed picture of long-range transport of polluted air masses and uplift events. MIPAS observations taken on 9–11 September 2003 confirm the trapping of convective outflow of polluted CO-rich air from

On the origin of subvisible cirrus clouds in the tropical upper troposphere

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M. Reverdy

2012-12-01

Full Text Available Spaceborne lidar observations have recently revealed a previously undetected significant population of Subvisible Cirrus (SVC. We show them to be colder than −74 °, with an optical depth below 0.0015 on average. The formation and persistence over time of this new cloud population could be related to several atmospheric phenomena. In this paper, we investigate if these clouds follow the same formation mechanisms as the general tropical cirrus population (including convection and in-situ ice nucleation, or if specific nucleation sites and trace species play a role in their formation. The importance of three scenarios in the formation of the global SVC population is investigated through different approaches that include comparisons with data imaging from several spaceborne instruments and back-trajectories that document the history and behavior of air masses leading to the point in time and space where subvisible cirrus were detected. In order to simplify the study of their formation, we singled out SVC with coherent temperature histories (mean variance lower than 4 K according to back-trajectories along 5, 10 or 15 days (respectively 58, 25 and 11% of SVC. Our results suggest that external processes, including local increases in liquid and hygroscopic aerosol concentration (either through biomass burning or volcanic injection forming sulfate-based aerosols in the troposphere or the stratosphere have very limited short-term or mid-term impact on the SVC population. On the other hand, we find that ~20% of air masses leading to SVC formation interacted with convective activity 5 days before they led to cloud formation and detection, a number that climbs to 60% over 15 days. SVC formation appears especially linked to convection over Africa and Central America, more so during JJA than DJF. These results support the view that the SVC population observed by CALIOP is an extension of the general upper tropospheric ice clouds population with its extreme

Mask humidity during CPAP: influence of ambient temperature, heated humidification and heated tubing

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Nilius G

2018-05-01

Full Text Available Georg Nilius,1,2 Ulrike Domanski,1 Maik Schroeder,1 Holger Woehrle,3,4 Andrea Graml,4 Karl-Josef Franke,1,2 1Helios Klinik Hagen-Ambrock, Department of Pneumology, Hagen, Germany; 2Department of Internal Medicine, Witten-Herdecke University, Witten, Germany; 3Sleep and Ventilation Center Blaubeuren, Respiratory Center Ulm, Ulm, Germany; 4ResMed Science Center, ResMed Germany, Martinsried, Germany Purpose: Mucosal drying during continuous positive airway pressure (CPAP therapy is problematic for many patients. This study assessed the influence of ambient relative humidity (rH and air temperature (T in winter and summer on mask humidity during CPAP, with and without mask leak, and with or without heated humidification ± heated tubing. Methods: CPAP (8 and 12 cmH2O without humidification (no humidity [nH], with heated humidification controlled by ambient temperature and humidity (heated humidity [HH] and HH plus heated tubing climate line (CL, with and without leakage, were compared in 18 subjects with OSA during summer and winter. Results: The absolute humidity (aH and the T inside the mask during CPAP were significantly lower in winter versus summer under all applied conditions. Overall, absolute humidity differences between summer and winter were statistically significant in both HH and CL vs. nH (p < 0.05 in the presence and absence of mouth leak. There were no significant differences in aH between HH and CL. However, in-mask temperature during CL was higher (p < 0.05 and rH lower than during HH. In winter, CPAP with CL was more likely to keep rH constant at 80% than CPAP without humidification or with standard HH. Conclusion: Clinically-relevant reductions in aH were documented during CPAP given under winter conditions. The addition of heated humidification, using a heated tube to avoid condensation is recommended to increase aH, which could be useful in CPAP users complaining of nose and throat symptoms. Keywords: continuous positive

Thermoeconomic Optimization of a Combined Heating and Humidification Coil for HVAC Systems

Science.gov (United States)

Teodoros, Liliana; Andresen, Bjarne

2016-07-01

The total cost of ownership is calculated for a combined heating and humidification coil of an air-handling unit taking into account investment and operation costs simultaneously. This total cost represents the optimization function for which the minimum is sought. The parameters for the cost dependencies are the physical dimensions of the coil: length, width and height. The term "coil" is used generically since in this setup it generates heating as well as humidification in a single unit. The first part of the paper deals with the constructive optimization and finds the relationship between the dimensions for a minimum cost. The second part of the paper takes the results of the constructive optimization further and, based on the data derived in our previous papers, analyzes the minimum total cost for the humidification coil while balancing the amount of water used to humidify the air and modify its temperature.

Inertia gravity waves in the upper troposphere during the MaCWAVE winter campaign. Part II. Radar investigations and modelling studies

Energy Technology Data Exchange (ETDEWEB)

Serafimovich, A.; Zuelicke, C.; Hoffmann, P.; Peters, D.; Singer, W. [Leibniz-Inst. fuer Atmosphaerenphysik, Kuehlungsborn (Germany); Dalin, P. [Swedish Inst. of Space Physics, Kiruna (Sweden)

2006-07-01

We present an experimental and modelling study of a strong gravity wave event in the upper troposphere/lower stratosphere near the Scandinavian mountain ridge. Continuous VHP radar measurements during the MaCWAVE rocket and ground-based measurement campaign were performed at the Norwegian Andoya rocket range (ARR) near Andenes (69.3 N, 16 E) in January 2003. Detailed gravity wave investigations based on PSU/NCAR fifth-generation mesoscale model (MM5) data have been used for comparison with experimentally obtained results. The model data show the presence of a mountain wave and of an inertia gravity wave generated by a jet streak near the tropopause region. Temporal and spatial dependencies of jet induced inertia gravity waves with dominant observed periods of about 13 h and vertical wavelengths of {proportional_to}4.5-5 km are investigated with wavelet transform applied on radar measurements and model data. The jet induced wave packet is observed to move upstream and downward in the upper troposphere. The model data agree with the experimentally obtained results fairly well. Possible reasons for the observed differences, e.g. in the time of maximum of the wave activity, are discussed. Finally, the vertical fluxes of horizontal momentum are estimated with different methods and provide similar amplitudes. We found indications that the derived positive vertical flux of the horizontal momentum corresponds to the obtained parameters of the jet-induced inertia gravity wave, but only at the periods and heights of the strongest wave activity. (orig.)

Investigation of inertia-gravity waves in the upper troposphere/lower stratosphere over Northern Germany observed with collocated VHF/UHF radars

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A. Serafimovich

2005-01-01

Full Text Available A case study to investigate the properties of inertia-gravity waves in the upper troposphere/lower stratosphere has been carried out over Northern Germany during the occurrence of an upper tropospheric jet in connection with a poleward Rossby wave breaking event from 17-19 December 1999. The investigations are based on the evaluation of continuous radar measurements with the OSWIN VHF radar at Kühlungsborn (54.1 N, 11.8 E and the 482 MHz UHF wind profiler at Lindenberg (52.2 N, 14.1 E. Both radars are separated by about 265 km. Based on wavelet transformations of both data sets, the dominant vertical wavelengths of about 2-4 km for fixed times as well as the dominant observed periods of about 11 h and weaker oscillations with periods of  6 h for the altitude range between 5 and 8 km are comparable. Gravity wave parameters have been estimated at both locations separately and by a complex cross-spectral analysis of the data of both radars. The results show the appearance of dominating inertia-gravity waves with characteristic horizontal wavelengths of  300 km moving in the opposite direction than the mean background wind and a secondary less pronounced wave with a horizontal wavelength in the order of about 200 km moving with the wind. Temporal and spatial differences of the observed waves are discussed.

Systematic studies of the gas humidification effects on spatial PEMFC performance distributions

International Nuclear Information System (INIS)

Reshetenko, Tatyana V.; Bender, Guido; Bethune, Keith; Rocheleau, Richard

2012-01-01

Highlights: ► We investigated impacts of gases humidification on a local PEMFC performance. ► The spatial performance and EIS were studied by a segmented cell system. ► The data were analyzed in the terms of voltage losses. ► A reduction in anode/cathode gases humidification decreased a PEMFC performance. ► A decrease of humidification led to non-uniform performances and voltage losses distributions. - Abstract: The overall current density that is measured in a proton exchange membrane fuel cell (PEMFC) represents the average of the local reaction rates. The overall and local PEMFC performances are determined by several primary loss mechanisms, namely activation, ohmic, and mass transfer. Spatial performance and loss variabilities are significant and depend on the cell design and operating conditions. A segmented cell system was used to quantify different loss distributions along the gas channel to understand the effects of gas humidification. A reduction in the reactant stream humidification decreased cell performance and resulted in non-uniform distributions of overpotentials and performance along the flow field. Activation and ohmic overpotentials increased with a relative humidity decrease due to insufficient membrane and catalyst layer hydration. The relative humidity of the cathode had a strong impact on the mass transfer overpotential due to a lower oxygen permeability through the dry Nafion film covering the catalyst surface. The mass transfer loss distribution was non-uniform, and the mass transfer overpotential increased for the outlet segments due to the oxygen consumption at the inlet segments, which reduced the oxygen concentration downstream, and a progressive water accumulation from upstream segments. Electrochemical impedance spectroscopy (EIS) and an equivalent electric circuit (EEC) facilitated the analysis and interpretation of the segmented cell data.

Potential impact of carbonaceous aerosol on the upper troposphere and lower stratosphere (UTLS) and precipitation during Asian summer monsoon in a global model simulation

KAUST Repository

Fadnavis, Suvarna

2017-09-28

Recent satellite observations show efficient vertical transport of Asian pollutants from the surface to the upper-level anticyclone by deep monsoon convection. In this paper, we examine the transport of carbonaceous aerosols, including black carbon (BC) and organic carbon (OC), into the monsoon anticyclone using of ECHAM6-HAM, a global aerosol climate model. Further, we investigate impacts of enhanced (doubled) carbonaceous aerosol emissions on the upper troposphere and lower stratosphere (UTLS), underneath monsoon circulation and precipitation from sensitivity simulations. The model simulation shows that boundary layer aerosols are transported into the monsoon anticyclone by the strong monsoon convection from the Bay of Bengal, southern slopes of the Himalayas and the South China Sea. Doubling of emissions of both BC and OC aerosols over Southeast Asia (10° S–50° N, 65–155° E) shows that lofted aerosols produce significant warming (0.6–1 K) over the Tibetan Plateau (TP) near 400–200 hPa and instability in the middle/upper troposphere. These aerosols enhance radiative heating rates (0.02–0.03 K day−1) near the tropopause. The enhanced carbonaceous aerosols alter aerosol radiative forcing (RF) at the surface by −4.74 ± 1.42 W m−2, at the top of the atmosphere (TOA) by +0.37 ± 0.26 W m−2 and in the atmosphere by +5.11 ± 0.83 W m−2 over the TP and Indo-Gangetic Plain region (15–35° N, 80–110° E). Atmospheric warming increases vertical velocities and thereby cloud ice in the upper troposphere. Aerosol induced anomalous warming over the TP facilitates the relative strengthening of the monsoon Hadley circulation and increases moisture inflow by strengthening the cross-equatorial monsoon jet. This increases precipitation amounts over India (1–4 mm day−1) and eastern China (0.2–2 mm day−1). These results are significant at the 99 % confidence level.

Upper-Level Waves of Synoptic Scale at Midlatitudes

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Rivest, Chantal

1990-01-01

Upper-level waves of synoptic scale are important dynamical entities at midlatitudes. They often induce surface cyclogenesis (cf. Peterssen and Smebye, 1971), and their life duration is typically longer than time scales for disruption by the ambient shear (Sanders, 1988). The objectives of the present thesis are to explain the maintenance and genesis of upper-level synoptic-scale waves in the midlatitude flow. We develop an analytical model of waves on generalized Eady basic states that have uniform tropospheric and stratospheric potential vorticity, but allow for the decay of density with height. The Eady basic state represents the limiting case of infinite stratospheric stability and constant density. We find that the Eady normal mode characteristics hold in the presence of realistic tropopause and stratosphere. In particular, the basic states studied support at the synoptic scale upper-level normal modes. These modes provide simple models for the dynamics of upper-level synoptic-scale waves, as waves supported by the large latitudinal gradients of potential vorticity at the tropopause. In the presence of infinitesimal positive tropospheric gradients of potential vorticity, the upper-level normal mode solutions no longer exist, as was demonstrated in Green (1960). Disappearance of the normal mode solution when a parameter changes slightly represents a dilemma that we seek to understand. We examine what happens to the upper-level normal modes in the presence of tropospheric gradients of potential vorticity in a series of initial -value experiments. Our results show that the normal modes become slowly decaying quasi-modes. Mathematically the quasi-modes consist of a superposition of singular modes sharply peaked in the phase speed domain, and their decay proceeds as the modes interfere with one another. We repeat these experiments in basic states with a smooth tropopause in the presence of tropospheric and stratospheric gradients, and similar results are obtained

Sub-seasonal temperature variability in the tropical upper troposphere and lower stratosphere observed with GPS radio occultation

Science.gov (United States)

Scherllin-Pirscher, Barbara; Randel, William J.; Kim, Joowan

2017-04-01

We investigate sub-seasonal temperature variability in the tropical upper troposphere and lower stratosphere (UTLS) region using daily gridded fields of GPS radio occultation measurements. The unprecedented vertical resolution (from about 100 m in the troposphere to about 1.5 km in the stratosphere) and high accuracy and precision (0.7 K to 1 K between 8 km and 25 km) make these data ideal for characterizing temperature oscillations with short vertical wavelengths. Long-term behavior of sub-seasonal temperature variability is investigated using the entire RO record from January 2002 to December 2014 (13 years of data). Transient sub-seasonal waves including eastward-propagating Kelvin waves (isolated with space-time spectral analysis) dominate large-scale zonal temperature variability in the tropical tropopause region and in the lower stratosphere. Above 20 km, Kelvin waves are strongly modulated by the quasi-biennial oscillation (QBO). Enhanced wave activity can be found during the westerly shear phase of the QBO. In the tropical tropopause region, however, sub-seasonal waves are highly transient in time. Several peaks of Kelvin-wave activity coincide with short-term fluctuations in tropospheric deep convection, but other episodes are not evidently related. Also, there are no obvious relationships with zonal winds or stability fields near the tropical tropopause. Further investigations of convective forcing and atmospheric background conditions along the waves' trajectories are needed to better understand sub-seasonal temperature variability near the tropopause. For more details, see Scherllin-Pirscher, B., Randel, W. J., and Kim, J.: Tropical temperature variability and Kelvin-wave activity in the UTLS from GPS RO measurements, Atmos. Chem. Phys., 17, 793-806, doi:10.5194/acp-17-793-2017, 2017. http://www.atmos-chem-phys.net/17/793/2017/acp-17-793-2017.html

Effect of Heated Humidification on CPAP Therapy Adherence in Subjects With Obstructive Sleep Apnea With Nasopharyngeal Symptoms.

Science.gov (United States)

Soudorn, Chuleekorn; Muntham, Dittapol; Reutrakul, Sirimon; Chirakalwasan, Naricha

2016-09-01

The addition of heated humidification to CPAP has been shown to improve nasal adverse effects in subjects with obstructive sleep apnea (OSA). However, current data regarding improvement in CPAP adherence is conflicting. Furthermore, there are no data from a tropical climate area with a high humidity level. In this prospective randomized crossover study conducted in Thailand, subjects with moderate to severe OSA with nasopharyngeal symptoms post-split-night study were enrolled in the study. Subjects were randomly assigned to receive CPAP with or without heated humidification for 4 weeks and then crossed over. Information on CPAP adherence, quality of life assessed by the Functional Outcomes of Sleep Questionnaire, nasopharyngeal symptoms assessed by a modified XERO questionnaire, and bedroom ambient humidity and temperature data were obtained. Data were collected on 20 subjects with OSA during the period of January to December 2014. Although the addition of heated humidification appeared to improve average hours of use for all days when compared with conventional CPAP, the difference was not statistically significant (CPAP with heated humidification = 4.6 ± 1.7 h/night; conventional CPAP = 4.0 ± 1.7 h/night, P = .1). However, the addition of heated humidification improved CPAP adherence on the days of use (5.5 ± 1.5 h/night) compared with conventional CPAP (5.2 ± 1.4 h/night), P = .033. Quality of life was also improved according to the Functional Outcomes of Sleep Questionnaire score (median 17.6 [interquartile range 3.5]) in the heated humidification group compared with conventional CPAP group (median 17.6 [interquartile range 4.5]), P = .046. Significant reduction in the dry throat/sore throat symptom was noted only when CPAP with heated humidification was used. Even in a tropical climate area, CPAP adherence and quality of life appeared to improve when heated humidification was employed in subjects with moderate to severe OSA with nasopharyngeal symptoms

Large differences in reanalyses of diabatic heating in the tropical upper troposphere and lower stratosphere

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J. S. Wright

2013-09-01

Full Text Available We present the time mean heat budgets of the tropical upper troposphere (UT and lower stratosphere (LS as simulated by five reanalysis models: the Modern-Era Retrospective Analysis for Research and Applications (MERRA, European Reanalysis (ERA-Interim, Climate Forecast System Reanalysis (CFSR, Japanese 25-yr Reanalysis and Japan Meteorological Agency Climate Data Assimilation System (JRA-25/JCDAS, and National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR Reanalysis 1. The simulated diabatic heat budget in the tropical UTLS differs significantly from model to model, with substantial implications for representations of transport and mixing. Large differences are apparent both in the net heat budget and in all comparable individual components, including latent heating, heating due to radiative transfer, and heating due to parameterised vertical mixing. We describe and discuss the most pronounced differences. Discrepancies in latent heating reflect continuing difficulties in representing moist convection in models. Although these discrepancies may be expected, their magnitude is still disturbing. We pay particular attention to discrepancies in radiative heating (which may be surprising given the strength of observational constraints on temperature and tropospheric water vapour and discrepancies in heating due to turbulent mixing (which have received comparatively little attention. The largest differences in radiative heating in the tropical UTLS are attributable to differences in cloud radiative heating, but important systematic differences are present even in the absence of clouds. Local maxima in heating and cooling due to parameterised turbulent mixing occur in the vicinity of the tropical tropopause.

Aqueous aerosol may build up large upper tropospheric ice supersaturation

Science.gov (United States)

Bogdan, Anatoli; Molina, Mario J.

2010-05-01

Keywords: ice supersaturation, upper tropospheric cirrus clouds, freezing of aqueous aerosol. Observations often reveal enhanced and persistent upper tropospheric (UT) ice supersaturation, Si up to 100%, independently of whether cirrus ice clouds are present or not (Krämer et al., 2009; Lawson et al., 2008). However, a water activity criterion (WAC) (Koop et al., 2000) does not allow the formation of Si > ~67% by the homogeneous freezing of aqueous droplets even at the lowest atmospheric temperature of ~185 K. For aqueous aerosol the WAC predicts the existence of a so called homogeneous ice nucleation threshold which, being expressed as Si, is between ~52 and 67% in the temperature range of ~220 - 185 K. The nature of the formation of large Si remains unclear. Since water vapor is the dominant greenhouse gas it is important to know the nature of the accumulation and persistence of water vapor in the UT. We studied the freezing behavior of micrometer-scaled 3-, 4-, and 5-component droplets, which contain different weight fractions of H2O, H2SO4, HNO3, (NH4)2SO4, (NH4)HSO4, NH4NO3, and (NH4)3H(SO4)2. The study was performed between 133 and 278 K at cooling rates of 3, 0.1, and 0.05 K/min using differential scanning calorimetry (DSC) (Bogdan and Molina, 2010). The cooling rates of 0.1 and 0.05 K/min (6 and 3 K/h) are similar to the smallest reported synoptic temperature change of ~2 K/h (Carslaw et al., 1998). Using the measured freezing temperature of ice, Ti, and the thermodynamic E-AIM model of the system of H+ - NH4+ - SO42-- NO3-- H2O (Clegg et al., 1998), we calculated the corresponding clear-sky Si which would be built up immediately prior to the formation of ice cirrus clouds by the homogeneous freezing of aqueous aerosol of similar composition. We found that our calculated values of Si are both larger and smaller than the homogeneous ice nucleation threshold. For example, for the droplets of compositions of 15/10 and 20/10 wt % (NH4)3H(SO4)2/H2SO4, which

Tropospheric Ozone as a Short-lived Chemical Climate Forcer

Science.gov (United States)

Pickering, Kenneth E.

2012-01-01

Tropospheric ozone is the third most important greenhouse gas according to the most recent IPCC assessment. However, tropospheric ozone is highly variable in both space and time. Ozone that is located in the vicinity of the tropopause has the greatest effect on climate forcing. Nitrogen oxides (NOx) are the most important precursors for ozone In most of the troposphere. Therefore, pollution that is lofted upward in thunderstorm updrafts or NOx produced by lightning leads to efficient ozone production in the upper troposphere, where ozone is most important climatically. Global and regional model estimates of the impact of North American pollution and lightning on ozone radiative forcing will be presented. It will be shown that in the Northern Hemisphere summer, the lightning effect on ozone radiative forcing can dominate over that of pollution, and that the radiative forcing signal from North America extends well into Europe and North Africa. An algorithm for predicting lightning flash rates and estimating lightning NOx emissions is being incorporated into the NASA GEOS-5 Chemistry and Climate Model. Changes in flash rates and emissions over an ENSO cycle and in future climates will be assessed, along with the resulting changes in upper tropospheric ozone. Other research on the production of NOx per lightning flash and its distribution in the vertical based on cloud-resolving modeling and satellite observations will be presented. Distributions of NO2 and O3 over the Middle East from the OMI instrument on NASA's Aura satellite will also be shown.

Humidification tower for humid air gas turbine cycles: Experimental analysis

International Nuclear Information System (INIS)

Traverso, A.

2010-01-01

In the HAT (humid air turbine) cycle, the humidification of compressed air can be provided by a pressurised saturator (i.e. humidification tower or saturation tower), this solution being known to offer several attractive features. This work is focused on an experimental study of a pressurised humidification tower, with structured packing. After a description of the test rig employed to carry out the measuring campaign, the results relating to the thermodynamic process are presented and discussed. The experimental campaign was carried out over 162 working points, covering a relatively wide range of possible operating conditions. It is shown that the saturator behaviour, in terms of air outlet humidity and temperature, is primarily driven by, in decreasing order of relevance, the inlet water temperature, the inlet water over inlet dry air mass flow ratio and the inlet air temperature. The exit relative humidity is consistently over 100%, which may be explained partially by measurement accuracy and droplet entrainment, and partially by the non-ideal behaviour of air-steam mixtures close to saturation. Experimental results have been successfully correlated using a set of new non-dimensional groups: such a correlation is able to capture the air outlet temperature with a standard deviation σ = 2.8 K.

Randomized controlled trial on postoperative pulmonary humidification after total laryngectomy: External humidifier versus heat and moisture exchanger

NARCIS (Netherlands)

Mérol, Jean-Claude; Charpiot, Anne; Langagne, Thibault; Hémar, Patrick; Ackerstaff, Annemieke H.; Hilgers, Frans J. M.

2012-01-01

Objectives/Hypothesis: Assessment of immediate postoperative airway humidification after total laryngectomy (TLE), comparing the use of an external humidifier (EH) with humidification through a heat and moisture exchanger (HME). Study Design: Randomized controlled trial (RCT). Methods: Fifty-three

Randomized controlled trial on postoperative pulmonary humidification after total laryngectomy: external humidifier versus heat and moisture exchanger

NARCIS (Netherlands)

Mérol, J.-C.; Charpiot, A.; Langagne, T.; Hémar, P.; Ackerstaff, A.H.; Hilgers, F.J.M.

2012-01-01

Objectives/Hypothesis: Assessment of immediate postoperative airway humidification after total laryngectomy (TLE), comparing the use of an external humidifier (EH) with humidification through a heat and moisture exchanger (HME). Study Design: Randomized controlled trial (RCT). Methods: Fifty-three

Use of a new novel humidification system with high frequency percussive ventilation in a patient with inhalation injury.

Science.gov (United States)

Jones, Samuel W; Short, Kathy A; Joseph, Mark; Sommer, Courtney; Cairns, Bruce A

2010-01-01

Historically, it has been difficult to provide adequate humidification delivery with the high frequency percussive ventilator (HFPV) used in many burn centers. It is possible burn centers have avoided using HFPV because of the risk of mucus plugging, dried secretions, and cast formation. Experiences with HFPV provided doubt that the HFPV ventilator circuit could supply adequate humidification to patients receiving this mode of ventilation. Independent gas-flow delivery through the ventilator circuit inherent in HFPV provided a challenge in maintaining adequate humidification delivery to the patient. This report describes a dramatic reduction in dried, inspissated secretions by using a novel new humidification device with HFPV. The new device called the Hydrate Omni (Hydrate, Inc., Midlothian, VA) uses a small ceramic disk to provide fine water particles delivered by a pump to the HFPV circuit. This new device may alleviate previous concerns related to the delivery of adequate humidification with the HFPV. This case report was approved by the University of North Carolina School of Medicine Institutional Review Board.

Evaluating a tobacco leaf humidification system involving nebulisation

Directory of Open Access Journals (Sweden)

Néstor Enrique Cerquera Peña

2010-05-01

Full Text Available A tobacco leaf humidifying system involving nebulisation was designned, implemented and evaluated; it had a system for monitoring and recording environmental conditions thereby producing an environment having more homogeneous relative humidity, ensuring better water use, better control of relative humidity and better control in managing cured tobacco leaf moisture content, thereby leading to a consequent improvement in final product quality. 55% to 75% relative humidity and 4 to 6 hour working ranges were obtained to en- sure leaf humidification reached 16% humidity on a wet basis. Two new designs are proposed for the conditioning stage regarding this conditioning chamber’s operational management, based on the results and field observations, which would allow better leaf management, thereby avoiding the risk of losses due to manipulation and over-humidification. This work strengthens research in the field of tobacco pos- tharvest technology, complementing other research projects which have been carried out in Colombia.

Humidification during high-frequency oscillatory ventilation for adults: a bench study.

Science.gov (United States)

Chikata, Yusuke; Imanaka, Hideaki; Ueta, Masahiko; Nishimura, Masaji

2010-12-01

High-frequency oscillatory ventilation (HFOV) has recently been applied to acute respiratory distress syndrome patients. However, the issue of humidification during HFOV has not been investigated. In a bench study, we evaluated humidification during HFOV for adults to test if adequate humidification was achieved in 2 different HFOV systems. We tested 2 brands of adult HFOV ventilators, the R100 (Metran, Japan) and the 3100B (SensorMedics, CA), under identical bias flow. A heated humidifier consisting of porous hollow fiber (Hummax II, Metran) was set for the R100, and a passover-type heated humidifier (MR850, Fisher & Paykel) was set for the 3100B, while inspiratory heating wire was applied to both systems. Each ventilator was connected to a lung model in an incubator. Absolute humidity, relative humidity and temperature at the airway opening were measured using a hygrometer under a variety of ventilatory settings: 3 stroke volumes/amplitudes, 3 frequencies, and 2 mean airway pressures. The R100 ventilator showed higher absolute humidity, higher relative humidity, and lower temperature than the 3100B. In the R100, as stroke volume and frequency increased, absolute humidity and temperature increased. In the 3100B, amplitude, frequency, and mean airway pressure minimally affected absolute humidity and temperature. Relative humidity was almost 100% in the R100, while it was 80.5±2.3% in the 3100B. Humidification during HFOV for adults was affected by stroke volume and frequency in the R100, but was not in the 3100B. Absolute humidity was above 33 mgH_2 O/L in these 2 systems under a range of settings.

Numerical simulation of humidification and heating during inspiration in nose models with three different located septal perforations.

Science.gov (United States)

Lindemann, Jörg; Reichert, Michael; Kröger, Ralf; Schuler, Patrick; Hoffmann, Thomas; Sommer, Fabian

2016-07-01

Nasal septum perforations (SP) are characterized by nasal obstruction, bleeding and crusting. The disturbed heating and humidification of the inhaled air are important factors, which cause these symptoms due to a disturbed airflow. Numerical simulations offer a great potential to avoid these limitations and to provide valid data. The aim of the study was to simulate the humidification and heating of the inhaled air in digital nose models with three different SPs and without SP. Four realistic bilateral nose models based on a multi-slice CT scan were created. The SP were located anterior caudal, anterior cranial and posterior caudal. One model was without SP. A numerical simulation was performed. Boundary conditions were based on previous in vivo measurements. Heating and humidification of the inhaled air were displayed, analyzed in each model and compared to each other. Anterior caudal SPs cause a disturbed decrease of temperature and humidity of the inhaled air. The reduced temperature and humidity values can still be shown in the posterior nose. The anterior cranial and the posterior caudal perforation have only a minor influence on heating and humidification. A reduced humidification and heating of the air can be shown by numerical simulations due to SP depending on their localization. The anterior caudal SP representing a typical localization after previous surgery has the biggest influence on heating and humidification. The results explain the typical symptoms such as crusting by drying-out the nasal mucosa. The size and the localization of the SP are essential for the symptoms.

Clinical outcome associated with the use of different inhalation method with and without humidification in asthmatic mechanically ventilated patients.

Science.gov (United States)

Moustafa, Islam O F; ElHansy, Muhammad H E; Al Hallag, Moataz; Fink, James B; Dailey, Patricia; Rabea, Hoda; Abdelrahim, Mohamed E A

2017-08-01

Inhaled-medication delivered during mechanical-ventilation is affected by type of aerosol-generator and humidity-condition. Despite many in-vitro studies related to aerosol-delivery to mechanically-ventilated patients, little has been reported on clinical effects of these variables. The aim of this study was to determine effect of humidification and type of aerosol-generator on clinical status of mechanically ventilated asthmatics. 72 (36 females) asthmatic subjects receiving invasive mechanical ventilation were enrolled and assigned randomly to 6 treatment groups of 12 (6 females) subjects each received, as possible, all inhaled medication using their assigned aerosol generator and humidity condition during delivery. Aerosol-generators were placed immediately after humidifier within inspiratory limb of mechanical ventilation circuit. First group used vibrating-mesh-nebulizer (Aerogen Solo; VMN) with humidification; Second used VMN without humidification; Third used metered-dose-inhaler with AeroChamber Vent (MDI-AV) with humidification; Forth used MDI-AV without humidification; Fifth used Oxycare jet-nebulizer (JN) with humidification; Sixth used JN without humidification. Measured parameters included clinical-parameters reflected patient response (CP) and endpoint parameters e.g. length-of-stay in the intensive-care-unit (ICU-days) and mechanical-ventilation days (MV-days). There was no significant difference between studied subjects in the 6 groups in baseline of CP. VMN resulted in trend to shorter ICU-days (∼1.42days) compared to MDI-AV (p = 0.39) and relatively but not significantly shorter ICU-days (∼0.75days) compared JN. Aerosol-delivery with or without humidification did not have any significant effect on any of parameters studied with very light insignificant tendency of delivery at humid condition to decrease MV-days and ICU-days. No significant effect was found of changing humidity during aerosol-delivery to ventilated-patient. VMN to deliver

Chemical processes related to net ozone tendencies in the free troposphere

Science.gov (United States)

Bozem, Heiko; Butler, Tim M.; Lawrence, Mark G.; Harder, Hartwig; Martinez, Monica; Kubistin, Dagmar; Lelieveld, Jos; Fischer, Horst

2017-09-01

Ozone (O3) is an important atmospheric oxidant, a greenhouse gas, and a hazard to human health and agriculture. Here we describe airborne in situ measurements and model simulations of O3 and its precursors during tropical and extratropical field campaigns over South America and Europe, respectively. Using the measurements, net ozone formation/destruction tendencies are calculated and compared to 3-D chemistry-transport model simulations. In general, observation-based net ozone tendencies are positive in the continental boundary layer and the upper troposphere at altitudes above ˜ 6 km in both environments. On the other hand, in the marine boundary layer and the middle troposphere, from the top of the boundary layer to about 6-8 km altitude, net O3 destruction prevails. The ozone tendencies are controlled by ambient concentrations of nitrogen oxides (NOx). In regions with net ozone destruction the available NOx is below the threshold value at which production and destruction of O3 balance. While threshold NO values increase with altitude, in the upper troposphere NOx concentrations are generally higher due to the integral effect of convective precursor transport from the boundary layer, downward transport from the stratosphere and NOx produced by lightning. Two case studies indicate that in fresh convective outflow of electrified thunderstorms net ozone production is enhanced by a factor 5-6 compared to the undisturbed upper tropospheric background. The chemistry-transport model MATCH-MPIC generally reproduces the pattern of observation-based net ozone tendencies but mostly underestimates the magnitude of the net tendency (for both net ozone production and destruction).

Evidence of Convective Redistribution of Carbon Monoxide in Aura Tropospheric Emission Sounder (TES) and Microwave Limb Sounder (MLS) Observations

Science.gov (United States)

Manyin, Michael; Douglass, Anne; Schoeberl, Mark

2010-01-01

Vertical convective transport is a key element of the tropospheric circulation. Convection lofts air from the boundary layer into the free troposphere, allowing surface emissions to travel much further, and altering the rate of chemical processes such as ozone production. This study uses satellite observations to focus on the convective transport of CO from the boundary layer to the mid and upper troposphere. Our hypothesis is that strong convection associated with high rain rate regions leads to a correlation between mid level and upper level CO amounts. We first test this hypothesis using the Global Modeling Initiative (GMI) chemistry and transport model. We find the correlation is robust and increases as the precipitation rate (the strength of convection) increases. We next examine three years of CO profiles from the Tropospheric Emission Sounder (TES) and Microwave Limb Sounder (MLS) instruments aboard EOS Aura. Rain rates are taken from the Tropical Rainfall Measuring Mission (TRMM) 3B-42 multi-satellite product. Again we find a correlation between mid-level and upper tropospheric CO, which increases with rain rate. Our result shows the critical importance of tropical convection in coupling vertical levels of the troposphere in the transport of trace gases. The effect is seen most clearly in strong convective regions such as the Inter-tropical Convergence Zone.

An experimental study of the air humidification process using a membrane contactor

Directory of Open Access Journals (Sweden)

Englart Sebastian

2017-01-01

Full Text Available The article presents the results of the experimental examination of the effectiveness of air humidification using a membrane module. The construction of the membrane module and the measuring stand is also discussed. In order to assess the effectiveness of air humidification using the membrane module, the measurements of temperature and humidity at the membrane module’s inlet and outlet, air flow rate, water flow rate and water temperature were taken. Based on the measurements, the effectiveness coefficients, E, have been determined. The power demand for the solution under study has also been discussed.

Thermodynamic constraint on the depth of the global tropospheric circulation.

Science.gov (United States)

Thompson, David W J; Bony, Sandrine; Li, Ying

2017-08-01

The troposphere is the region of the atmosphere characterized by low static stability, vigorous diabatic mixing, and widespread condensational heating in clouds. Previous research has argued that in the tropics, the upper bound on tropospheric mixing and clouds is constrained by the rapid decrease with height of the saturation water vapor pressure and hence radiative cooling by water vapor in clear-sky regions. Here the authors contend that the same basic physics play a key role in constraining the vertical structure of tropospheric mixing, tropopause temperature, and cloud-top temperature throughout the globe. It is argued that radiative cooling by water vapor plays an important role in governing the depth and amplitude of large-scale dynamics at extratropical latitudes.

Changes in ocular and nasal signs and symptoms among air crew in relation to air humidification on intercontinental flights.

Science.gov (United States)

Norbäck, Dan; Lindgren, Torsten; Wieslander, Gunilla

2006-04-01

This study evaluates the influence of air humidification in aircraft on symptoms, tear-film stability, nasal patency, and peak expiratory flow. Commercial air crew (N=71) were given a medical examination during eight flights from Stockholm to Chicago and eight flights in the opposite direction. Examinations were done onboard one Boeing 767 aircraft equipped with an evaporation humidifier in the forward part of the cabin. The investigators followed the air crew, staying one night in Chicago and returning with the same crew. Four of the flights had the air humidification device active in-flight to Chicago and deactivated when returning to Stockholm. The other four flights had the inverse humidification sequence. The humidification sequence was randomized and double blind. Hygienic measurements were performed. The humidification increased the relative air humidity by 10% in the 1st row in business class, by 3% in the last row (39th row) in tourist class, and by 3% in the cockpit. Air humidification increased tear-film stability and nasal patency and decreased ocular, nasal, and dermal symptoms and headache. The mean concentration of viable bacteria [77-108 colony-forming units (cfu)/m(3)], viable molds (74-84 cfu/m(3)), and particulate matter (1-8 microg/m(3)) was low, both during the humidified and non-humidified flights. Relative air humidity is low (10-12%) during intercontinental flights and can be increased by the use of a ceramic evaporation humidifier, without any measurable increase of microorganisms in cabin air. Air humidification could increase passenger and crew comfort by increasing tear-film stability and nasal patency and reducing various symptoms.

Inertia gravity waves in the upper troposphere during the MaCWAVE winter campaign – Part II: Radar investigations and modelling studies

Directory of Open Access Journals (Sweden)

A. Serafimovich

2006-11-01

Full Text Available We present an experimental and modelling study of a strong gravity wave event in the upper troposphere/lower stratosphere near the Scandinavian mountain ridge. Continuous VHF radar measurements during the MaCWAVE rocket and ground-based measurement campaign were performed at the Norwegian Andoya Rocket Range (ARR near Andenes (69.3° N, 16° E in January 2003. Detailed gravity wave investigations based on PSU/NCAR Fifth-Generation Mesoscale Model (MM5 data have been used for comparison with experimentally obtained results. The model data show the presence of a mountain wave and of an inertia gravity wave generated by a jet streak near the tropopause region. Temporal and spatial dependencies of jet induced inertia gravity waves with dominant observed periods of about 13 h and vertical wavelengths of ~4.5–5 km are investigated with wavelet transform applied on radar measurements and model data. The jet induced wave packet is observed to move upstream and downward in the upper troposphere. The model data agree with the experimentally obtained results fairly well. Possible reasons for the observed differences, e.g. in the time of maximum of the wave activity, are discussed. Finally, the vertical fluxes of horizontal momentum are estimated with different methods and provide similar amplitudes. We found indications that the derived positive vertical flux of the horizontal momentum corresponds to the obtained parameters of the jet-induced inertia gravity wave, but only at the periods and heights of the strongest wave activity.

The Governing Processes and Timescales of Stratosphere-to-Troposphere Transport and its Contribution to Ozone in the Arctic Troposphere

Science.gov (United States)

Liang, Q.; Douglass, A. R.; Duncan, B. N.; Stolarski, R. S.; Witte, J. C.

2009-01-01

We used the seasonality of a combination of atmospheric trace gases and idealized tracers to examine stratosphere-to-troposphere transport and its influence on tropospheric composition in the Arctic. Maximum stratosphere-to-troposphere transport of CFCs and O3 occurs in April as driven by the Brewer-Dobson circulation. Stratosphere-troposphere exchange (STE) occurs predominantly between 40 deg N to 80 deg N with stratospheric influx in the mid-latitudes (30-70 deg N) accounting for 67.81 percent of the air of stratospheric origin in the Northern Hemisphere extratropical troposphere. Transport from the lower stratosphere to the lower troposphere (LT) takes three months on average, one month to cross the tropopause, the second month to travel from the upper troposphere (UT) to the middle troposphere (MT), and the third month to reach the LT. During downward transport, the seasonality of a trace gas can be greatly impacted by wet removal and chemistry. A comparison of idealized tracers with varying lifetimes suggests that when initialized with the same concentrations and seasonal cycles at the tropopause, trace gases that have shorter lifetimes display lower concentrations, smaller amplitudes, and earlier seasonal maxima during transport to the LT. STE contributes to O3 in the Arctic troposphere directly from the transport of O3 and indirectly from the transport of NOy . Direct transport of O3 from the stratosphere accounts for 78 percent of O3 in the Arctic UT with maximum contributions occurring from March to May. The stratospheric contribution decreases significantly in the MT/LT (20.25 percent of total O3) and shows a very weak March.April maximum. Our NOx budget analysis in the Arctic UT shows that during spring and summer, the stratospheric injection of NO y-rich air increases NOx concentrations above the 20 pptv threshold level, thereby shifting the Arctic UT from a regime of net photochemical ozone loss to one of net production with rates as high as +16 ppbv/month.

The governing processes and timescales of stratosphere-to-troposphere transport and its contribution to ozone in the Arctic troposphere

Science.gov (United States)

Liang, Q.; Douglass, A. R.; Duncan, B. N.; Stolarski, R. S.; Witte, J. C.

2009-05-01

We used the seasonality of a combination of atmospheric trace gases and idealized tracers to examine stratosphere-to-troposphere transport and its influence on tropospheric composition in the Arctic. Maximum stratosphere-to-troposphere transport of CFCs and O3 occurs in April as driven by the Brewer-Dobson circulation. Stratosphere-troposphere exchange (STE) occurs predominantly between 40° N to 80° N with stratospheric influx in the mid-latitudes (30-70° N) accounting for 67-81% of the air of stratospheric origin in the Northern Hemisphere extratropical troposphere. Transport from the lower stratosphere to the lower troposphere (LT) takes three months on average, one month to cross the tropopause, the second month to travel from the upper troposphere (UT) to the middle troposphere (MT), and the third month to reach the LT. During downward transport, the seasonality of a trace gas can be greatly impacted by wet removal and chemistry. A comparison of idealized tracers with varying lifetimes suggests that when initialized with the same concentrations and seasonal cycles at the tropopause, trace gases that have shorter lifetimes display lower concentrations, smaller amplitudes, and earlier seasonal maxima during transport to the LT. STE contributes to O3 in the Arctic troposphere directly from the transport of O3 and indirectly from the transport of NOy. Direct transport of O3 from the stratosphere accounts for 78% of O3 in the Arctic UT with maximum contributions occurring from March to May. The stratospheric contribution decreases significantly in the MT/LT (20-25% of total O3) and shows a very weak March-April maximum. Our NOx budget analysis in the Arctic UT shows that during spring and summer, the stratospheric injection of NOy-rich air increases NOx concentrations above the 20 pptv threshold level, thereby shifting the Arctic UT from a regime of net photochemical ozone loss to one of net production with rates as high as +16 ppbv/month.

Airway humidification with a heated wire humidifier during high-frequency ventilation using Babylog 8000 plus in neonates.

Science.gov (United States)

Nagaya, Ken; Okamoto, Toshio; Nakamura, Eiki; Hayashi, Tokitsugi; Fujieda, Kenji

2009-03-01

Little data are available on airway humidity during high-frequency ventilation (HFV). Our purpose is to evaluate the airway humidification during HFV. We examined the airway humidification and temperature in a neonatal HFV system using Babylog 8000 plus. The absolute humidity (AH), relative humidity (RH), and temperature at different sites and under different HFV conditions were compared with those during conventional intermittent positive pressure ventilation (IPPV). The mean AH and RH at the patient end of the respiratory circuit under 37 degrees C in the humidification chamber (HC) during HFV were less than 35 mg/L and 65%, respectively, while those during IPPV were 42.3 mg/L and 96.8%, respectively. The humidification at the outlet of the HC was similar results. Moreover, during HFV an increase in the bias-flow of ventilator led to a further decrease in the humidity at the patient end of respiratory circuit and the outlet of HC. It was necessary to set the temperature in the HC at >39 degrees C to maintain adequate humidity at the HC and the patient end of respiratory circuit during HFV. An increase in the incubator temperature led to an increase in the temperature at the patient end of the respiratory circuit. The temperature at the patient end of the respiratory circuit was about 39-40 degrees C when the incubator temperature was 35-37 degrees C. The airway humidification at the patient end of respiratory circuit and the outlet of HC in HFV were poorer than those in IPPV. However, the adequacy of humidification and safety in HFV remain to be demonstrated in clinical practice.

Influence of vapor absorption cooling on humidification-dehumidification (HDH desalination

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C. Chiranjeevi

2016-09-01

Full Text Available The desalination yield in humidification-dehumidification (HDH process is increased by proposing cooling plant integration with two stage operation. The current work is targeted on the investigation of vapor absorption refrigeration (VAR parameters on overall energy utilization factor (EUF. The dephlegmator heat is recovered internally in VAR instead of rejecting to environment. This work can be used to control the operational conditions of VAR to enhance the desalination and cooling together. The studied process parameters in VAR are strong solution concentration, separator or generator temperature, dephlegmator effectiveness, circulating water inlet temperature and evaporator temperature. Out of these five variables, lower limit of separator temperature, upper limit of dephlegmator effectiveness and lower limit of circulating water temperature are fixed in the specified range to attain the optimum strong solution concentration and optimum evaporator temperature. At the specified boundaries of three variables, the optimized strong solution concentration and evaporator temperature are 0.47 and 10 °C respectively. At this condition, the maximized cycle EUF is 0.358.

Oxalic acid as a heterogeneous ice nucleus in the upper troposphere and its indirect aerosol effect

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B. Zobrist

2006-01-01

Full Text Available Heterogeneous ice freezing points of aqueous solutions containing various immersed solid dicarboxylic acids (oxalic, adipic, succinic, phthalic and fumaric have been measured with a differential scanning calorimeter. The results show that only the dihydrate of oxalic acid (OAD acts as a heterogeneous ice nucleus, with an increase in freezing temperature between 2 and 5 K depending on solution composition. In several field campaigns, oxalic acid enriched particles have been detected in the upper troposphere with single particle aerosol mass spectrometry. Simulations with a microphysical box model indicate that the presence of OAD may reduce the ice particle number density in cirrus clouds by up to ~50% when compared to exclusively homogeneous cirrus formation without OAD. Using the ECHAM4 climate model we estimate the global net radiative effect caused by this heterogeneous freezing to result in a cooling as high as −0.3 Wm−2.

Regular in situ measurements of HDO/H216O in the northern and southern hemispherical upper troposphere reveal tropospheric transport processes.

Science.gov (United States)

Christner, Emanuel; Dyroff, Christoph; Sanati, Shahrokh; Brenninkmeijer, Carl; Zahn, Andreas

2013-04-01

influence of convection on the isotopic composition of water in the upper troposphere. This finding is consistent with the well-known regions of deep convection over Africa, Malaysia and South America.

Improvement of OMI Ozone Profile Retrievals in the Troposphere and Lower Troposphere by the Use of the Tropopause-Based Ozone Profile Climatology

Science.gov (United States)

Bak, Juseon; Liu, X.; Wei, J.; Kim, J. H.; Chance, K.; Barnet, C.

2011-01-01

An advance algorithm based on the optimal estimation technique has beeen developed to derive ozone profile from GOME UV radiances and have adapted it to OMI UV radiances. OMI vertical resolution : 7-11 km in the troposphere and 10-14 km in the stratosphere. Satellite ultraviolet measurements (GOME, OMI) contain little vertical information for the small scale of ozone, especially in the upper troposphere (UT) and lower stratosphere (LS) where the sharp O3 gradient across the tropopause and large ozone variability are observed. Therefore, retrievals depend greatly on the a-priori knowledge in the UTLS

Experimental study on the self-humidification effect in proton exchange membrane fuel cells containing double gas diffusion backing layer

International Nuclear Information System (INIS)

Kong, Im Mo; Choi, Jong Won; Kim, Sung Il; Lee, Eun Sook; Kim, Min Soo

2015-01-01

Highlights: • Investigated self-humidification effect of structurally modified GDBLs in PEMFCs. • One conventional and two modified GDLs were prepared. • Structural design of the GDBLs significantly affected self-humidification. • Stacking was found to have negligible effect on self-humidification. • It can be applied readily to self-humidified PEMFCs. - Abstract: Adequate hydration of the membrane is required to ensure high proton conductivity in proton exchange membrane fuel cells (PEMFCs), which, in turn, is required for achieving high cell performances. While external humidifiers are typically used to humidify the supplied air in conventional systems, their use increases the complexity, weight, volume, and parasitic power loss in fuel cell systems, rendering them unviable in some systems, particularly for portable applications. In this study, the structure of a gas diffusion backing layer (GDBL) was modified to enhance the self-humidification effect in PEMFCs. Three types of GDLs were prepared for the experiments: a conventional GDL (GDL-A with uniform single GDBL) and two modified GDLs (GDL-A′B with uniform double GDBL and GDL-A′C with heterogeneous double GDBLs). In order to evaluate the effect of stacking and structural design on the self-humidification characteristics, some characteristics of the GDLs such as contact angle, resistance, and vapor permeation rate were measured. The electrochemical performances of the fuel cells were also measured at various relative humidity (RH) and stoichiometric ratio (SR) conditions. The results showed that stacking had a negligible effect, whereas the structural design of the GDBL had a significant effect on self-humidification. The self-humidification effect and the cell performance were improved significantly in the structurally modified GDBL. In addition, considering the actual field conditions and the results of the present study, it was concluded that the structural modifications made to the GDBL would

Model Calculations of Changes in Tropospheric Ozone Over Europe and the Role of Surface Sources and Aircraft Emissions

Energy Technology Data Exchange (ETDEWEB)

Hov, Oe [Bergen Univ. (Norway)

1996-01-01

This conference paper deals with a study of the impact of various sources of NO{sub x} on the ozone production in the free troposphere. A comprehensive two-dimensional zonally averaged chemistry/transport model and a three-dimensional meso-scale chemical transport (MCT) model are used in the study. Using the two-dimensional model, three surches of NO{sub x} in the upper troposphere were examined covering NO{sub x} produced by lightening, NO{sub x} (and NO{sub y}) brought to the upper troposphere from the planetary boundary layer by rapid vertical transport processes, and NO{sub x} emitted from aircraft. 4 refs.

Influence of the Gulf Stream on the troposphere.

Science.gov (United States)

Minobe, Shoshiro; Kuwano-Yoshida, Akira; Komori, Nobumasa; Xie, Shang-Ping; Small, Richard Justin

2008-03-13

The Gulf Stream transports large amounts of heat from the tropics to middle and high latitudes, and thereby affects weather phenomena such as cyclogenesis and low cloud formation. But its climatic influence, on monthly and longer timescales, remains poorly understood. In particular, it is unclear how the warm current affects the free atmosphere above the marine atmospheric boundary layer. Here we consider the Gulf Stream's influence on the troposphere, using a combination of operational weather analyses, satellite observations and an atmospheric general circulation model. Our results reveal that the Gulf Stream affects the entire troposphere. In the marine boundary layer, atmospheric pressure adjustments to sharp sea surface temperature gradients lead to surface wind convergence, which anchors a narrow band of precipitation along the Gulf Stream. In this rain band, upward motion and cloud formation extend into the upper troposphere, as corroborated by the frequent occurrence of very low cloud-top temperatures. These mechanisms provide a pathway by which the Gulf Stream can affect the atmosphere locally, and possibly also in remote regions by forcing planetary waves. The identification of this pathway may have implications for our understanding of the processes involved in climate change, because the Gulf Stream is the upper limb of the Atlantic meridional overturning circulation, which has varied in strength in the past and is predicted to weaken in response to human-induced global warming in the future.

Effect of some climatic parameters on tropospheric and total ozone ...

Indian Academy of Sciences (India)

carbon, carbon monoxide, nitrogen dioxide, and sulphur dioxide) that are collected from India Meteo- rological Department .... and the upper troposphere is not only able to absorb ... lar traffic, thermal power plants, very busy ports, small and ...

A model study of ozone in the eastern Mediterranean free troposphere during MINOS (August 2001

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G. J. Roelofs

2003-01-01

Full Text Available A coupled tropospheric chemistry-climate model is used to analyze tropospheric ozone distributions observed during the MINOS campaign in the eastern Mediterranean region (August, 2001. Modeled ozone profiles are generally in good agreement with the observations. Our analysis shows that the atmospheric dynamics in the region are strongly influenced by the occurrence of an upper tropospheric anti-cyclone, associated with the Asian summer monsoon and centered over the Tibetan Plateau. The anti-cyclone affects the chemical composition of the upper troposphere, where ozone concentrations of about 50 ppbv were measured, through advection of boundary layer air from South-East Asia. A layer between 4-6 km thickness was present beneath, containing up to 120 ppbv of ozone with substantial contributions by transport from the stratosphere and through lightning NOx. Additionally, pollutant ozone from North America was mixed in. Ozone in the lower troposphere originated mainly from the European continent. The stratospheric influence may be overestimated due to too strong vertical diffusion associated with the relatively coarse vertical resolution. The estimated tropospheric ozone column over the eastern Mediterranean is ~50 DU in summer, to which ozone from recent stratospheric origin contributes about 30%, ozone from lightning 13%, and from South-East Asia, North America and Europe about 7%, 8% and 14%, respectively, adding to a long-term hemispheric background of 25% of the column.

Improving environmental performance of post-harvest supply chains of fruits and vegetables in Europe: Potential contribution from ultrasonic humidification

DEFF Research Database (Denmark)

Fabbri, Serena; Olsen, Stig Irving; Owsianiak, Mikołaj

2018-01-01

Post-harvest losses of fruits and vegetables during refrigerated storage, transportation and retail are an important contributor to total environmental impacts of food supply chains in Europe. Ultrasonic humidification can reduce these post-harvest losses, but it is currently unknown whether...... that humidification may be an attractive technology for making supply chain management more sustainable....... implementing the technology in practice improves the environmental performance of the supply chains. Here, using life cycle assessment we showed that ultrasonic humidification has the potential to reduce environmental impacts, including climate change impacts, of selected fruits and vegetables in Europe by up...

Humidification mitigates acute mucosal toxicity during radiotherapy when factoring volumetric parameters. Trans Tasman Radiation Oncology Group (TROG) RadioHUM 07.03 substudy.

Science.gov (United States)

Macann, A; Fauzi, F; Simpson, J; Sasso, G; Krawitz, H; Fraser-Browne, C; Manitz, J; Raith, A

2017-12-01

To model in a subset of patients from TROG 07.03 managed at a single site the association between domiciliary based humidification use and mucositis symptom burden during radiotherapy (RT) for head and neck cancer (HNC) when factoring in volumetric radiotherapy parameters derived from tumour and normal tissue regions of interest. From June 2008 through June 2011, 210 patients with HNC receiving RT were randomised to either a control arm or humidification using the Fisher & Paykel Healthcare MR880 humidifier. This subset analysis involves patients recruited from Auckland City Hospital treated with a prescribed dose of ≥70 Gy. Regression models included control variables for Planning Target Volume 70 GY (PTV70Gy); Equivalent Uniform Dose (EUD) MOIST and TSV (surrogates of total mucosal and total swallowing volumes respectively). The analysis included 39 patients (humidification 20, control 19). There was a significant odds reduction in CTCAE v3.0 functional mucositis score of 0.29 associated with the use of humidification (pfactor of 11.11 for humidification patients (p=.013). The results support the hypothesis that humidification can help mitigate mucositis symptom burden. Radiotherapy dosimetric parameters assist in the evaluation of toxicity interventions. Copyright © 2017 Elsevier Ltd. All rights reserved.

Sulfur dioxide (SO2 from MIPAS in the upper troposphere and lower stratosphere 2002–2012

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M. Höpfner

2015-06-01

Full Text Available Vertically resolved distributions of sulfur dioxide (SO2 with global coverage in the height region from the upper troposphere to ~20 km altitude have been derived from observations by the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS on Envisat for the period July 2002 to April 2012. Retrieved volume mixing ratio profiles representing single measurements are characterized by typical errors in the range of 70–100 pptv and by a vertical resolution ranging from 3 to 5 km. Comparison with observations by the Atmospheric Chemistry Experiment Fourier transform spectrometer (ACE-FTS revealed a slightly varying bias with altitude of −20 to 50 pptv for the MIPAS data set in case of volcanically enhanced concentrations. For background concentrations the comparison showed a systematic difference between the two major MIPAS observation periods. After debiasing, the difference could be reduced to biases within −10 to 20 pptv in the altitude range of 10–20 km with respect to ACE-FTS. Further comparisons of the debiased MIPAS data set with in situ measurements from various aircraft campaigns showed no obvious inconsistencies within a range of around ±50 pptv. The SO2 emissions of more than 30 volcanic eruptions could be identified in the upper troposphere and lower stratosphere (UTLS. Emitted SO2 masses and lifetimes within different altitude ranges in the UTLS have been derived for a large part of these eruptions. Masses are in most cases within estimations derived from other instruments. From three of the major eruptions within the MIPAS measurement period – Kasatochi in August 2008, Sarychev in June 2009 and Nabro in June 2011 – derived lifetimes of SO2 for the altitude ranges 10–14, 14–18 and 18–22 km are 13.3 ± 2.1, 23.6 ± 1.2 and 32.3 ± 5.5 days respectively. By omitting periods with obvious volcanic influence we have derived background mixing ratio distributions of SO2. At 10 km altitude these indicate an annual

Assessment of upper tropospheric and stratospheric water vapor and ozone in reanalyses as part of S-RIP

Science.gov (United States)

Davis, Sean M.; Hegglin, Michaela I.; Fujiwara, Masatomo; Dragani, Rossana; Harada, Yayoi; Kobayashi, Chiaki; Long, Craig; Manney, Gloria L.; Nash, Eric R.; Potter, Gerald L.; Tegtmeier, Susann; Wang, Tao; Wargan, Krzysztof; Wright, Jonathon S.

2017-10-01

Reanalysis data sets are widely used to understand atmospheric processes and past variability, and are often used to stand in as "observations" for comparisons with climate model output. Because of the central role of water vapor (WV) and ozone (O3) in climate change, it is important to understand how accurately and consistently these species are represented in existing global reanalyses. In this paper, we present the results of WV and O3 intercomparisons that have been performed as part of the SPARC (Stratosphere-troposphere Processes and their Role in Climate) Reanalysis Intercomparison Project (S-RIP). The comparisons cover a range of timescales and evaluate both inter-reanalysis and observation-reanalysis differences. We also provide a systematic documentation of the treatment of WV and O3 in current reanalyses to aid future research and guide the interpretation of differences amongst reanalysis fields.The assimilation of total column ozone (TCO) observations in newer reanalyses results in realistic representations of TCO in reanalyses except when data coverage is lacking, such as during polar night. The vertical distribution of ozone is also relatively well represented in the stratosphere in reanalyses, particularly given the relatively weak constraints on ozone vertical structure provided by most assimilated observations and the simplistic representations of ozone photochemical processes in most of the reanalysis forecast models. However, significant biases in the vertical distribution of ozone are found in the upper troposphere and lower stratosphere in all reanalyses.In contrast to O3, reanalysis estimates of stratospheric WV are not directly constrained by assimilated data. Observations of atmospheric humidity are typically used only in the troposphere, below a specified vertical level at or near the tropopause. The fidelity of reanalysis stratospheric WV products is therefore mainly dependent on the reanalyses' representation of the physical drivers that

Study on bubble column humidification and dehumidification system for coal mine wastewater treatment.

Science.gov (United States)

Gao, Penghui; Zhang, Meng; Du, Yuji; Cheng, Bo; Zhang, Donghai

2018-04-01

Water is important resource for human survival and development. Coal mine wastewater (CMW) is a byproduct of the process of coal mining, which is about 7.0 × 10 10 m 3 in China in 2016. Considering coal mine wastewater includes different ingredients, a new bubble column humidification and dehumidification system is proposed for CMW treatment. The system is mainly composed of a bubble column humidification and dehumidification unit, solar collector, fan and water tank, in which air is used as a circulating medium. The system can avoid water treatment component blocking for reverse osmosis (RO) and multi effect distillation (MED) dealing with CMW, and produce water greenly. By analysis of heat and mass transfer, the effects of solar radiation, air bubble velocity and mine water temperature on water treatment production characteristics are studied. Compared with other methods, thermal energy consumption (TEC) of bubble column humidification and dehumidification (BCHD) is moderate, which is about 700 kJ/kg (powered by solar energy). The results would provide a new method for CMW treatment and insights into the efficient coal wastewater treatment, besides, it helps to identify the parameters for the technology development in mine water treatment.

Randomized controlled trial on postoperative pulmonary humidification after total laryngectomy: external humidifier versus heat and moisture exchanger.

Science.gov (United States)

Mérol, Jean-Claude; Charpiot, Anne; Langagne, Thibault; Hémar, Patrick; Ackerstaff, Annemieke H; Hilgers, Frans J M

2012-02-01

Assessment of immediate postoperative airway humidification after total laryngectomy (TLE), comparing the use of an external humidifier (EH) with humidification through a heat and moisture exchanger (HME). Randomized controlled trial (RCT). Fifty-three patients were randomized into the standard (control) EH (N = 26) or the experimental HME arm (N = 27). Compliance, pulmonary and sleeping problems, patients' and nursing staff satisfaction, nursing time, and cost-effectiveness were assessed with trial-specific structured questionnaires and tally sheets. In the EH arm data were available for all patients, whereas in the HME arm data were incomplete for four patients. The 24/7 compliance rate in the EH arm was 12% and in the HME arm 87% (77% if the four nonevaluable patients are considered noncompliant). Compliance and patients' satisfaction were significantly better, and the number of coughing episodes, mucus expectoration for clearing the trachea, and sleeping disturbances were significantly less in the HME arm (P humidification by means of an HME over the use of an EH after TLE. This study therefore underlines that HMEs presently can be considered the better option for early postoperative airway humidification after TLE. Copyright © 2011 The American Laryngological, Rhinological, and Otological Society, Inc.

The representation of tropical upper tropospheric water in EC Earth V2

Energy Technology Data Exchange (ETDEWEB)

Johnston, M.S. [Chalmers University of Technology, Department of Earth and Space Sciences, Goeteburg (Sweden); Swedish Meteorological and Hydrological Institute (SMHI), Norrkoeping (Sweden); Eriksson, P.; Murtagh, D.P. [Chalmers University of Technology, Department of Earth and Space Sciences, Goeteburg (Sweden); Eliasson, S. [Luleaa University of Technology, Department of Computer Science, Electrical and Space Engineering, Kiruna (Sweden); Jones, C.G. [Swedish Meteorological and Hydrological Institute (SMHI), Norrkoeping (Sweden); Forbes, R.M. [ECMWF, Reading, Berkshire (United Kingdom)

2012-12-15

Tropical upper tropospheric humidity, clouds, and ice water content, as well as outgoing longwave radiation (OLR), are evaluated in the climate model EC Earth with the aid of satellite retrievals. The Atmospheric Infrared Sounder and Microwave Limb Sounder together provide good coverage of relative humidity. EC Earth's relative humidity is in fair agreement with these observations. CloudSat and CALIPSO data are combined to provide cloud fractions estimates throughout the altitude region considered (500-100 hPa). EC Earth is found to overestimate the degree of cloud cover above 200 hPa and underestimate it below. Precipitating and non-precipitating EC Earth ice definitions are combined to form a complete ice water content. EC Earth's ice water content is below the uncertainty range of CloudSat above 250 hPa, but can be twice as high as CloudSat's estimate in the melting layer. CERES data show that the model underestimates the impact of clouds on OLR, on average with about 9 W m{sup -2}. Regionally, EC Earth's outgoing longwave radiation can be {proportional_to}20 W m{sup -2} higher than the observation. A comparison to ERA-Interim provides further perspectives on the model's performance. Limitations of the satellite observations are emphasised and their uncertainties are, throughout, considered in the analysis. Evaluating multiple model variables in parallel is a more ambitious approach than is customary. (orig.)

Continental outflow from the US to the upper troposphere over the North Atlantic during the NASA INTEX-NA Airborne Campaign

Directory of Open Access Journals (Sweden)

S. Y. Kim

2008-04-01

Full Text Available A case of continental outflow from the United States (US was examined using airborne measurements from NASA DC-8 flight 13 during the Intercontinental Chemical Transport Experiment – North America (INTEX-NA. Mixing ratios of methane (CH₄ and carbon monoxide (CO at 8–11 km altitude over the North Atlantic were elevated to 1843 ppbv and 134 ppbv respectively, while those of carbon dioxide (CO₂ and carbonyl sulfide (COS were reduced to 372.4 ppmv and 411 pptv respectively. In this region, urban and industrial influences were evidenced by elevated mixing ratios and good linear relationships between urban and industrial tracers compared to North Atlantic background air. Moreover, low mixing ratios and a good correlation between COS and CO₂ showed a fingerprint of terrestrial uptake and minimal dilution during rapid transport over a 1–2 day time period. Analysis of synoptic conditions, backward trajectories, and photochemical aging estimates based on C₃H₈/C₂H₆ strongly suggested that elevated anthropogenic tracers in the upper troposphere of the flight region were the result of transport via convection and warm conveyor belt (WCB uplifting of boundary layer air over the southeastern US. This mechanism is supported by the similar slope values of linear correlations between long-lived (months anthropogenic tracers (e.g., C₂Cl₄ and CHCl₃ from the flight region and the planetary boundary layer in the southeastern US. In addition, the aircraft measurements suggest that outflow from the US augmented the entire tropospheric column at mid-latitudes over the North Atlantic. Overall, the flight 13 data demonstrate a pervasive impact of US anthropogenic emissions on the troposphere over the North Atlantic.

The effects of de-humidification and O{sub 2} direct injection in oxy-PC combustion

Energy Technology Data Exchange (ETDEWEB)

Choi, C.G.; Na, I.H.; Lee, J.W.; Chae, T.Y.; Yang, W. [Korea Insitute of Industrial Technology, Seoul (Korea, Republic of). Energy System R and D Dept.

2013-07-01

This study is aimed to derive effects of de-humidification and O{sub 2} direct injection in oxy-PC combustion system. Temperature distribution and flue gas composition were observed for various air and oxy-fuel conditions such as effect of various O{sub 2} concentration of total oxidant, O{sub 2} concentration of primary stream and O{sub 2} direct injection through 0-D heat and mass balance calculation and experiments in the oxy-PC combustion system of 0.3 MW scale in KITECH (Korea Institute of Industrial Technology). Flame attachment characteristic related to O{sub 2} direct injection was also observed experimentally. We found that FEGT (furnace exit gas temperature) of 100% de-humidification to oxidizer is lower than humidification condition; difference between two conditions is lower than 20 C in all cases. The efficiency changing of combustion was negligible in O{sub 2} direct injection. But O{sub 2} direct injection should be carefully designed to produce a stable flame.

Solar Desalination by Humidification-Dehumidification of Air

OpenAIRE

Moumouh J.; Tahiri M.; Balli L.

2018-01-01

The importance of supplying potable water can hardly be overstressed. In many arid zones, coastal or inlands, seawater or brackish water desalination may be the only solution to the shortage of fresh water. The process based on humidification-dehumidification of air (HDH) principle mimic the natural water cycle. HDH technique has been subjected to many studies in recent years due to the low temperature, renewable energy use, simplicity, low cost installation and operation. An experimental tes...

Humidification of incubators.

Science.gov (United States)

Harpin, V A; Rutter, N

1985-01-01

The effect of increasing the humidity in incubators was examined in 62 infants of less than 30 weeks' gestation. Thirty three infants nursed in high humidity for two weeks were compared retrospectively with 29 infants from an earlier study who were nursed under plastic bubble blankets or with topical paraffin but without raised humidity. Humidification reduced skin water loss and improved maintenance of body temperature from birth, but did not delay the normal postnatal maturation of the skin. Infants nursed without humidity frequently became hypothermic in spite of a high incubator air temperature. These advantages must be weighed against the finding that overheating was more common and Pseudomonas was more commonly isolated from the infants. It is recommended that incubator humidity is raised for babies under 30 weeks' gestation in the first days of life but meticulous attention should be paid to fluid balance, avoiding overheating, and cleansing of the humidifier reservoir. PMID:3985653

Impact of heated humidification with automatic positive airway pressure in obstructive sleep apnea therapy.

Science.gov (United States)

Salgado, Sara Moreira da Silva Trindade; Boléo-Tomé, José Pedro Correia Fernandes; Canhão, Cristina Maria Sardinha; Dias, Ana Rita Tavares; Teixeira, Joana Isaac; Pinto, Paula Maria Gonçalves; Caetano, Maria Cristina de Brito Eusébio Bárbara Prista

2008-09-01

To study the impact that heated humidification instituted in the beginning of automatic positive airway pressure (APAP) therapy has on compliance with and the side effects of the treatment. Thirty-nine treatment-naïve patients with obstructive sleep apnea were randomized into two groups to receive APAP using one of two modalities: with heated humidification (APAPwith group); and without heated humidification (APAPw/o group).Patients were evaluated at 7 and 30 days after APAP initiation. The following parameters were analyzed: compliance with treatment (mean number of hours/night); side effects (dry nose or mouth, nasal obstruction and rhinorrhea); daytime sleepiness (Epworth sleepiness scale score) and subjective comfort (visual analog scale score). Patients were also evaluated in terms of residual apnea-hypopnea index (AHI), as well as mean pressures and leaks registered in the ventilators. There were no differences between the two groups in terms of mean age (APAPwith: 57.4 +/- 9.2; APAPw/o: 56.5 +/- 10.7 years), AHI (APAPwith: 28.1 +/- 14.0; APAPw/o: 28.8 +/- 20.5 events/hour of sleep), baseline Epworth score (APAPwith: 11.2 +/- 5.8; APAPw/o: 11.9 +/- 6.3) and initial nasal symptoms. Compliance was similar in both groups (APAPwith: 5.3 +/- 2.4; APAPw/o: 5.2 +/- 2.3 h/night). There were no differences in any of the other parameters analyzed. The introduction of heated humidification at the beginning of APAP therapy provided no advantage in terms of treatment compliance or side effects of treatment.

Humidification performance of 48 passive airway humidifiers: comparison with manufacturer data.

Science.gov (United States)

Lellouche, François; Taillé, Solenne; Lefrançois, Frédéric; Deye, Nicolas; Maggiore, Salvatore Maurizio; Jouvet, Philippe; Ricard, Jean-Damien; Fumagalli, Bruno; Brochard, Laurent

2009-02-01

Heat and moisture exchangers (HMEs) are increasingly used in the ICU for gas conditioning during mechanical ventilation. Independent assessments of the humidification performance of HMEs are scarce. The aim of the present study was thus to assess the humidification performance of a large number of adult HMEs. We assessed 48 devices using a bench test apparatus that simulated real-life physiologic ventilation conditions. Thirty-two devices were described by the manufacturers as HMEs, and 16 were described as antibacterial filters. The test apparatus provided expiratory gases with an absolute humidity (AH) of 35 mg H(2)O/L. The AH of inspired gases was measured after steady state using the psychrometric method. We performed three hygrometric measurements for each device, measured their resistance, and compared our results with the manufacturer data. Of the 32 HMEs tested, only 37.5% performed well (>or= 30 mg H(2)O/L), while 25% performed poorly ( 4 mg H(2)O/L. The mean difference for the antibacterial filters was 0.2 +/- 1.4 mg H(2)O/L. The mean resistance of all the tested devices was 2.17 +/- 0.70 cm H(2)O/L/s. Several HMEs performed poorly and should not be used as HMEs. The values determined by independent assessments may be lower than the manufacturer data. Describing a device as an HME does not guarantee that it provides adequate humidification. The performance of HMEs must be verified by independent assessment.

NASA Goddard Earth Sciences Graduate Student Program. [FIRE CIRRUS-II examination of coupling between an upper tropospheric cloud system and synoptic-scale dynamics

Science.gov (United States)

Ackerman, Thomas P.

1994-01-01

The evolution of synoptic-scale dynamics associated with a middle and upper tropospheric cloud event that occurred on 26 November 1991 is examined. The case under consideration occurred during the FIRE CIRRUS-II Intensive Field Observing Period held in Coffeyville, KS during Nov. and Dec., 1991. Using data from the wind profiler demonstration network and a temporally and spatially augmented radiosonde array, emphasis is given to explaining the evolution of the kinematically-derived ageostrophic vertical circulations and correlating the circulation with the forcing of an extensively sampled cloud field. This is facilitated by decomposing the horizontal divergence into its component parts through a natural coordinate representation of the flow. Ageostrophic vertical circulations are inferred and compared to the circulation forcing arising from geostrophic confluence and shearing deformation derived from the Sawyer-Eliassen Equation. It is found that a thermodynamically indirect vertical circulation existed in association with a jet streak exit region. The circulation was displaced to the cyclonic side of the jet axis due to the orientation of the jet exit between a deepening diffluent trough and building ridge. The cloud line formed in the ascending branch of the vertical circulation with the most concentrated cloud development occurring in conjunction with the maximum large-scale vertical motion. The relationship between the large scale dynamics and the parameterization of middle and upper tropospheric clouds in large-scale models is discussed and an example of ice water contents derived from a parameterization forced by the diagnosed vertical motions and observed water vapor contents is presented.

A change in humidification system can eliminate endotracheal tube occlusion.

Science.gov (United States)

Doyle, Alex; Joshi, Manasi; Frank, Peter; Craven, Thomas; Moondi, Parvez; Young, Peter

2011-12-01

Inadequate airway humidification can result in endotracheal tube occlusion. There is evidence that heat and moisture exchangers (HMEs) are more prone to endotracheal tube occlusion than heated humidifiers (HHs) that contain a heated wire circuit. We aimed to compare the incidence of endotracheal tube occlusion while introducing a new dual-heated wire circuit HH in place of an established hydrophobic HME. This was a prospective observational study. All patients who required intubation were included in our analysis. Univariate statistical analysis was performed using a Fisher exact test. P humidification exclusively by HH. In the subsequent 18-month period, there were no further episodes of endotracheal tube occlusion. Our study demonstrates that there is a significant increase in the incidence of endotracheal tube occlusion when using a hydrophobic HME compared with an HH and that using a dual-heated wire circuit HH can eliminate endotracheal tube occlusion. Copyright © 2011 Elsevier Inc. All rights reserved.

Analysis of the summertime buildup of tropospheric ozone abundances over the Middle East and North Africa as observed by the Tropospheric Emission Spectrometer instrument

Science.gov (United States)

Liu, Jane J.; Jones, Dylan B. A.; Worden, John R.; Noone, David; Parrington, Mark; Kar, Jay

2009-03-01

We use the GEOS-Chem chemical transport model to interpret observations of tropospheric ozone from the Tropospheric Emission Spectrometer (TES) satellite instrument in summer 2005. Observations from TES reveal elevated ozone in the middle troposphere (500-400 hPa) across North Africa and the Middle East. Observed ozone abundances in the middle troposphere are at a maximum in summer and a minimum in winter, consistent with the previously predicted summertime "Middle East ozone maximum." This summertime enhancement in ozone is associated with the Arabian and Sahara anticyclones, centered over the Zagros and Atlas Mountains, respectively. These anticyclones isolate the middle troposphere over northeast Africa and the Middle East, with westerlies to the north and easterlies to the south, facilitating the buildup of ozone. Over the Middle East, we find that in situ production and transport from Asia provides comparable contributions of 30-35% to the ozone buildup. Over North Africa, in situ production is dominant (at about 20%), with transport from Asia, North America, and equatorial Africa each contributing about 10-15% to the total ozone. We find that although the eastern Mediterranean is characterized by strong descent in the middle and upper troposphere in summer, transport from the boundary layer accounts for about 25% of the local Middle Eastern contribution to the ozone enhancement in the middle troposphere. This upward transport of boundary layer air is associated with orographic lifting along the Zagros Mountains in Iran and the Asir and Hijaz Mountain ranges in Saudi Arabia, and is consistent with TES observations of deuterated water.

Tropospheric ozone climatology at two Southern Hemisphere tropical/subtropical sites, (Reunion Island and Irene, South Africa from ozonesondes, LIDAR, and in situ aircraft measurements

Directory of Open Access Journals (Sweden)

G. Clain

2009-03-01

Full Text Available This paper presents a climatology and trends of tropospheric ozone in the Southwestern Indian Ocean (Reunion Island and South Africa (Irene and Johannesburg. This study is based on a multi-instrumental dataset: PTU-O₃ ozonesondes, DIAL LIDAR and MOZAIC airborne instrumentation.

The seasonal profiles of tropospheric ozone at Reunion Island have been calculated from two different data sets: ozonesondes and LIDAR. The two climatological profiles are similar, except in austral summer when the LIDAR profiles show greater values in the free troposphere, and in the upper troposphere when the LIDAR profiles show lower values during all seasons. These results show that the climatological value of LIDAR profiles must be discussed with care since LIDAR measurements can be performed only under clear sky conditions, and the upper limit of the profile depends on the signal strength.

In addition, linear trends have been calculated from ozonesonde data at Reunion and Irene. Considering the whole tropospheric column, the trend is slightly positive for Reunion, and more clearly positive for Irene. Trend calculations have also been made separating the troposphere into three layers, and separating the dataset into seasons. Results show that the positive trend for Irene is governed by the lower layer that is affected by industrial pollution and biomass burning. On the contrary, for Reunion Island, the strongest trends are observed in the upper troposphere, and in winter when stratosphere-troposphere exchange is more frequently expected.

First airborne water vapor lidar measurements in the tropical upper troposphere and mid-latitudes lower stratosphere: accuracy evaluation and intercomparisons with other instruments

Directory of Open Access Journals (Sweden)

C. Schiller

2008-09-01

Full Text Available In the tropics, deep convection is the major source of uncertainty in water vapor transport to the upper troposphere and into the stratosphere. Although accurate measurements in this region would be of first order importance to better understand the processes that govern stratospheric water vapor concentrations and trends in the context of a changing climate, they are sparse because of instrumental shortcomings and observational challenges. Therefore, the Falcon research aircraft of the Deutsches Zentrum für Luft- und Raumfahrt (DLR flew a zenith-viewing water vapor differential absorption lidar (DIAL during the Tropical Convection, Cirrus and Nitrogen Oxides Experiment (TROCCINOX in 2004 and 2005 in Brazil. The measurements were performed alternatively on three water vapor absorption lines of different strength around 940 nm. These are the first aircraft DIAL measurements in the tropical upper troposphere and in the mid-latitudes lower stratosphere. Sensitivity analyses reveal an accuracy of 5% between altitudes of 8 and 16 km. This is confirmed by intercomparisons with the Fast In-situ Stratospheric Hygrometer (FISH and the Fluorescent Advanced Stratospheric Hygrometer (FLASH onboard the Russian M-55 Geophysica research aircraft during five coordinated flights. The average relative differences between FISH and DIAL amount to −3%±8% and between FLASH and DIAL to −8%±14%, negative meaning DIAL is more humid. The average distance between the probed air masses was 129 km. The DIAL is found to have no altitude- or latitude-dependent bias. A comparison with the balloon ascent of a laser absorption spectrometer gives an average difference of 0%±19% at a distance of 75 km. Six tropical DIAL under-flights of the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS on board ENVISAT reveal a mean difference of −8%±49% at an average distance of 315 km. While the comparison with MIPAS is somewhat less significant due to poorer

Active versus passive humidification for self-ventilating tracheostomy and laryngectomy patients: a systematic review of the literature.

Science.gov (United States)

Wong, C Y Y; Shakir, A A; Farboud, A; Whittet, H B

2016-12-01

To determine whether active or passive humidification methods are more effective in preventing pulmonary complications in self-ventilating neck breather patients. Systematic Review adhering to PRISMA guidance (checklist sourced from www.equator-network.org/). Review of current published relevant literature at a tertiary department of Otolaryngology and Head & Neck Surgery. We included all separate studies and comparison studies of active and passive humidification techniques in adult and paediatric neck breather patients. The primary outcome is the reduction in pulmonary complications. Secondary outcomes include patient compliance; carer and user satisfaction. Seven studies were included in this review: two RCTs (133 patients), one randomised controlled cross-over trial (29 patients), three randomised prospective studies (171 patients), and one retrospective study (73 patients). Only one study was conducted on paediatric neck breathers. The overall quality of the studies was low. Five studies were at a high risk of bias. Of the remaining two studies, one study had a low risk of bias and the other had an unclear risk. Despite limited subject evidence, results show that passive methods of humidification (mainly HME) is the preferred choice of humidification in the spontaneously breathing neck breather patients group mainly due to the reduction in pulmonary complaints, and better patient compliance. © 2015 John Wiley & Sons Ltd.

The use of satellite data to determine the distribution of ozone in the troposphere

Science.gov (United States)

Fishman, Jack; Watson, Catherine E.; Brackett, Vincent G.; Fakhruzzaman, Khan; Veiga, Robert E.

1991-01-01

Measurements from two independent satellite data sets have been used to derive the climatology of the integrated amount of ozone in the troposphere. These data have led to the finding that large amounts of ozone pollution are generated by anthropogenic activity originating from both the industrialized regions of the Northern Hemisphere and from the southern tropical regions of Africa. To verify the existence of this ozone anomaly at low latitudes, an ozonesonde capability has been established at Ascension Island (8 deg S, 15 deg W) since July 1990. According to the satellite analyses, Ascension Island is located downwind of the primary source region of this ozone pollution, which likely results from the photochemical oxidation of emissions emanating from the widespread burning of savannas and other biomass. These in situ measurements confirm the existence of large amounts of ozone in the lower atmosphere. A summary of these ozonesonde data to date will be presented. In addition, we will present some ozone profile measurements from SAGE II which can be used to provide upper tropospheric ozone measurements directly in the tropical troposphere. A preliminary comparison between the satellite observations and the ozonesonde profiles in the upper troposphere and lower stratosphere will also be presented.

An experimental study on the cathode humidification and evaporative cooling of polymer electrolyte membrane fuel cells using direct water injection method at high current densities

International Nuclear Information System (INIS)

Hwang, Seong Hoon; Kim, Min Soo

2016-01-01

Highlights: • Proposal of a cathode humidification and evaporative cooling system for PEM fuel cells. • An external-mixing air-assist atomizer is used to produce a very fine water spray. • The system is effective in both cathode humidification and stack cooling. • Increased water flow rate improves stack performance and evaporative cooling capacity. • At a given water flow rate, lower stack temperatures cause greater humidification effect. - Abstract: Humidification and cooling are critical issues in enhancing the efficiency and durability of polymer electrolyte membrane fuel cells (PEMFCs). However, existing humidifiers and cooling systems have the disadvantage that they must be quite large to achieve adequate PEMFC performance. In this study, to eliminate the need for a bulky humidifier and to lighten the cooling load of PEMFCs, a cathode humidification and evaporative cooling system using an external-mixing air-assist atomizer was developed and its performance was investigated. The atomization performance of the nozzle was analyzed experimentally under various operating conditions with minimal changes in the system design. Experiments with a five-cell PEMFC stack with an active area of 250 cm"2 were carried out to analyze the effects of various parameters (such as the operating temperature, current density, and water injection flow rate) on the evaporation of injected water for humidification and cooling performances. The experimental results demonstrate that the direct water injection method proposed in this study is quite effective in cathode humidification and stack cooling in PEM fuel cells at high current densities. The stack performance was improved by humidification effect and the coolant temperature at the stack outlet decreased by evaporative cooling effect.

Momentum flux associated with gravity waves in the low-latitude troposphere

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S. R. Prabhakaran Nayar

Full Text Available The vertical fluxes of horizontal momentum at tropospheric heights are calculated for four days, 25–28 August 1999. The mean zonal wind during these days show the presence of strong westward wind at the upper troposphere. Both the symmetric beam radar method and the power spectral method of evaluation of vertical flux of zonal and meridional momentum shows nearly the same result for quiet conditions. The temporal evolution of the momentum flux is estimated for a day with strong zonal shear and convection. These results indicate that on 28 August 1999, the strong downward vertical wind in the lower altitude range is associated with upward vertical flux of zonal momentum, and strong upward vertical wind is associated with downward vertical flux. Similarly, the strong shear in zonal wind is associated with the increase in negative values in vertical flux in the upper troposphere. Analysis of the role of wave periods in the transport of momentum flux indicates that the vertical momentum flux magnitude is not evenly distributed in all wave periods, but instead it peaks at certain wave periods in the range 10 to 100 min.

Key words. Meteorology and atmospheric dynamics (convective process; tropical meteorology; precipitation

Mid-upper tropospheric methane retrieval from IASI and its validation

Directory of Open Access Journals (Sweden)

X. Xiong

2013-09-01

Full Text Available Mid-upper tropospheric methane (CH4, as an operational product at NOAA's (National Oceanic and Atmospheric Administration Comprehensive Large Array-data Stewardship System (CLASS, has been retrieved from the Infrared Atmospheric Sounding Interferometer (IASI since 2008. This paper provides a description of the retrieval method and the validation using 596 CH4 vertical profiles from aircraft measurements by the HIAPER Pole-to-Pole Observations (HIPPO program over the Pacific Ocean. The number of degrees of freedom for the CH4 retrieval is mostly less than 1.5, and it decreases under cloudy conditions. The retrievals show greatest sensitivity between 100–600 hPa in the tropics and 200–750 hPa in the mid- to high latitude. Validation is accomplished using aircraft measurements (convolved by applying the monthly mean averaging kernels collocated with all the retrieved profiles within 200 km and on the same day, and the results show that, on average, a larger error of CH4 occurs at 300–500 hPa. The bias in the trapezoid of 374–477 hPa is −1.74% with a residual standard deviation of 1.20%, and at layer 596–753 hPa the bias is −0.69% with a residual standard deviation of 1.07%. The retrieval error is relatively larger in the high northern latitude regions and/or under cloudy conditions. The main reasons for this negative bias include the uncertainty in the spectroscopy near the methane Q branch and/or the empirical bias correction, plus residual cloud contamination in the cloud-cleared radiances. It is expected for NOAA to generate the CH4 product for 20 + years using a similar algorithm from three similar thermal infrared sensors: Atmospheric Infrared Sounder (AIRS, IASI and the Cross-track Infrared Sounder (CrIS. Such a unique product will provide a supplementary to the current ground-based observation network, particularly in the Arctic, for monitoring the CH4 cycle, its transport and trend associated with climate change.

Effect of air humidification on the sick building syndrome and perceived indoor air quality in hospitals: a four month longitudinal study.

Science.gov (United States)

Nordström, K; Norbäck, D; Akselsson, R

1994-01-01

The sensation of dryness and irritation is essential in the sick building syndrome (SBS), and such symptoms are common in both office and hospital employees. In Scandinavia, the indoor relative humidity in well ventilated buildings is usually in the range 10-35% in winter. The aim of this study was to evaluate the effect of steam air humidification on SBS and perceived air quality during the heating season. The study base consisted of a dynamic population of 104 hospital employees, working in four new and well ventilated geriatric hospital units in southern Sweden. Air humidification raised the relative air humidity to 40-45% in two units during a four months period, whereas the other two units served as controls with relative humidity from 25-35%. Symptoms and perceived indoor air quality were measured before and after the study period by a standardised self administered questionnaire. The technical measurements comprised room temperature, air humidity, static electricity, exhaust air flow, aerosols, microorganisms, and volatile organic compounds in the air. The most pronounced effect of the humidification was a significant decrease of the sensation of air dryness, static electricity, and airway symptoms. After four months of air humidification during the heating season, 24% reported a weekly sensation of dryness in humidified units, compared with 73% in controls. No significant changes in symptoms of SBS or perceived air quality over time were found in the control group. The room temperature in all units was between 21-23 degrees C, and no significant effect of air humidification on the air concentration of aerosols or volatile organic compounds was found. No growth of microorganisms was found in the supply air ducts, and no legionella bacteria were found in the supply water of the humidifier. Air humidification, however, significantly reduced the measured personal exposure to static electricity. It is concluded that air humidification during the heating season

Aerosol delivery and humidification with the Boussignac continuous positive airway pressure device.

Science.gov (United States)

Thille, Arnaud W; Bertholon, Jean-François; Becquemin, Marie-Hélène; Roy, Monique; Lyazidi, Aissam; Lellouche, François; Pertusini, Esther; Boussignac, Georges; Maître, Bernard; Brochard, Laurent

2011-10-01

A simple method for effective bronchodilator aerosol delivery while administering continuing continuous positive airway pressure (CPAP) would be useful in patients with severe bronchial obstruction. To assess the effectiveness of bronchodilator aerosol delivery during CPAP generated by the Boussignac CPAP system and its optimal humidification system. First we assessed the relationship between flow and pressure generated in the mask with the Boussignac CPAP system. Next we measured the inspired-gas humidity during CPAP, with several humidification strategies, in 9 healthy volunteers. We then measured the bronchodilator aerosol particle size during CPAP, with and without heat-and-moisture exchanger, in a bench study. Finally, in 7 patients with acute respiratory failure and airway obstruction, we measured work of breathing and gas exchange after a β(2)-agonist bronchodilator aerosol (terbutaline) delivered during CPAP or via standard nebulization. Optimal humidity was obtained only with the heat-and-moisture exchanger or heated humidifier. The heat-and-moisture exchanger had no influence on bronchodilator aerosol particle size. Work of breathing decreased similarly after bronchodilator via either standard nebulization or CPAP, but P(aO(2)) increased significantly only after CPAP aerosol delivery. CPAP bronchodilator delivery decreases the work of breathing as effectively as does standard nebulization, but produces a greater oxygenation improvement in patients with airway obstruction. To optimize airway humidification, a heat-and-moisture exchanger could be used with the Boussignac CPAP system, without modifying aerosol delivery.

Humidification performance of heat and moisture exchangers for pediatric use.

Science.gov (United States)

Chikata, Yusuke; Sumida, Chihiro; Oto, Jun; Imanaka, Hideaki; Nishimura, Masaji

2012-01-01

Background. While heat and moisture exchangers (HMEs) have been increasingly used for humidification during mechanical ventilation, the efficacy of pediatric HMEs has not yet been fully evaluated. Methods. We tested ten pediatric HMEs when mechanically ventilating a model lung at respiratory rates of 20 and 30 breaths/min and pressure control of 10, 15, and 20 cmH(2)O. The expiratory gas passed through a heated humidifier. We created two rates of leakage: 3.2 L/min (small) and 5.1 L/min (large) when pressure was 10 cmH(2)O. We measured absolute humidity (AH) at the Y-piece. Results. Without leakage, eight of ten HMEs maintained AH at more than 30 mg/L. With the small leak, AH decreased below 30 mg/L (26.6 to 29.5 mg/L), decreasing further (19.7 to 27.3 mg/L) with the large leak. Respiratory rate and pressure control level did not affect AH values. Conclusions. Pediatric HMEs provide adequate humidification performance when leakage is absent.

Humidification Performance of Heat and Moisture Exchangers for Pediatric Use

Directory of Open Access Journals (Sweden)

Yusuke Chikata

2012-01-01

Full Text Available Background. While heat and moisture exchangers (HMEs have been increasingly used for humidification during mechanical ventilation, the efficacy of pediatric HMEs has not yet been fully evaluated. Methods. We tested ten pediatric HMEs when mechanically ventilating a model lung at respiratory rates of 20 and 30 breaths/min and pressure control of 10, 15, and 20 cmH2O. The expiratory gas passed through a heated humidifier. We created two rates of leakage: 3.2 L/min (small and 5.1 L/min (large when pressure was 10 cmH2O. We measured absolute humidity (AH at the Y-piece. Results. Without leakage, eight of ten HMEs maintained AH at more than 30 mg/L. With the small leak, AH decreased below 30 mg/L (26.6 to 29.5 mg/L, decreasing further (19.7 to 27.3 mg/L with the large leak. Respiratory rate and pressure control level did not affect AH values. Conclusions. Pediatric HMEs provide adequate humidification performance when leakage is absent.

A Laser-Induced Fluorescence Instrument for Aircraft Measurements of Sulfur Dioxide in the Upper Troposphere and Lower Stratosphere

Science.gov (United States)

Rollins, Andrew W.; Thornberry, Troy D.; Ciciora, Steven J.; McLaughlin, Richard J.; Watts, Laurel A.; Hanisco, Thomas F.; Baumann, Esther; Giorgetta, Fabrizio R.; Bui, Thaopaul V.; Fahey, David W.

2016-01-01

This work describes the development and testing of a new instrument for in situ measurements of sulfur dioxide (SO2) on airborne platforms in the upper troposphere and lower stratosphere (UTLS). The instrument is based on the laser-induced fluorescence technique and uses the fifth harmonic of a tunable fiber-amplified semiconductor diode laser system at 1084.5 nm to excite SO2 at 216.9 nm. Sensitivity and background checks are achieved in flight by additions of SO2 calibration gas and zero air, respectively. Aircraft demonstration was performed during the NASA Volcano Plume Investigation Readiness and Gas-Phase and Aerosol Sulfur (VIRGAS) experiment, which was a series of flights using the NASA WB-57F during October 2015 based at Ellington Field and Harlingen, Texas. During these flights, the instrument successfully measured SO2 in the UTLS at background (non-volcanic) conditions with a precision of 2 ppt at 10 s and an overall uncertainty determined primarily by instrument drifts of +/- (16% + 0.9 ppt).

A simple climatology of westerly jet streams in global reanalysis datasets part 1: mid-latitude upper tropospheric jets

Science.gov (United States)

Rikus, Lawrie

2018-04-01

A simple closed contour object identification scheme has been applied to the zonal mean monthly mean zonal wind fields from nine global reanalysis data sets for 31 years of the satellite era (1979-2009) to identify objects corresponding to westerly jet streams. The results cluster naturally into six individual jet streams but only the mid-latitude upper-tropospheric jets are considered here. The time series of the jet properties from all reanalyses are decomposed into seasonal means and anomalies, and correlations between variables are evaluated, with the aim of identifying robust features which can form the basis of evaluation metrics for climate model simulations of the twentieth century. There is substantial agreement between all the reanalyses for all jet properties although there are some systematic differences with particular data sets. Some of the results from the object identification applied to the reanalyses are used in a simple example of a model evaluation score for the zonal mean jet seasonal cycle.

Heated CO(2) with or without humidification for minimally invasive abdominal surgery.

Science.gov (United States)

Birch, Daniel W; Manouchehri, Namdar; Shi, Xinzhe; Hadi, Ghassan; Karmali, Shahzeer

2011-01-19

Intraoperative hypothermia during both open and laparoscopic abdominal surgery may be associated with adverse events. For laparoscopic abdominal surgery, the use of heated insufflation systems for establishing pneumoperitoneum has been described to prevent hypothermia. Humidification of the insufflated gas is also possible. Past studies have shown inconclusive results with regards to maintenance of core temperature and reduction of postoperative pain and recovery times. To determine the effect of heated gas insufflation on patient outcomes following minimally invasive abdominal surgery. The Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library), MEDLINE (PubMed), EMBASE, International Pharmaceutical Abstracts (IPA), Web of Science, Scopus, www.clinicaltrials.gov and the National Research Register were searched (1956 to 14 June 2010). Grey literature and cross-references were also searched. Searches were limited to human studies without language restriction. All included studies were randomized trials comparing heated (with or without humidification) gas insufflation with cold gas insufflation in adult and pediatric populations undergoing minimally invasive abdominal procedures. Study quality was assessed in regards to relevance, design, sequence generation, allocation concealment, blinding, possibility of incomplete data and selective reporting. The selection of studies for the review was done independently by two authors, with any disagreement resolved in consensus with a third co-author. Screening of eligible studies, data extraction and methodological quality assessment of the trials were performed by the authors. Data from eligible studies were collected using data sheets. Results were presented using mean differences for continuous outcomes and relative risks with 95% confidence intervals for dichotomous outcomes. The estimated effects were calculated using the latest version of RevMan software. Publication bias was taken into

Inadequate humidification of respiratory gases during mechanical ventilation of the newborn.

Science.gov (United States)

Tarnow-Mordi, W O; Sutton, P; Wilkinson, A R

1986-01-01

Proximal airway humidity was measured during mechanical ventilation in 14 infants using an electronic hygrometer. Values below recommended minimum humidity of adult inspired gas were recorded on 251 of 396 occasions. Inadequate humidification, largely due to inadequate proximal airway temperature, is commoner than recognised in infants receiving mechanical ventilation. PMID:3740912

Effects of regional-scale and convective transports on tropospheric ozone chemistry revealed by aircraft observations during the wet season of the AMMA campaign

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G. Ancellet

2009-01-01

Full Text Available The African Monsoon Multidisciplinary Analyses (AMMA fourth airborne campaign was conducted in July–August 2006 to study the chemical composition of the middle and upper troposphere in West Africa with the major objective to better understand the processing of chemical emissions by the West African Monsoon (WAM and its associated regional-scale and vertical transports. In particular, the french airborne experiment was organized around two goals. The first was to characterize the impact of Mesoscale Convective Systems (MCSs on the ozone budget in the upper troposphere and the evolution of the chemical composition of these convective plumes as they move westward toward the Atlantic Ocean. The second objective was to discriminate the impact of remote sources of pollution over West Africa, including transport from the middle east, Europe, Asia and from southern hemispheric fires. Observations of O₃, CO, NO_x, H₂O and hydroperoxide above West Africa along repeated meridional transects were coupled with transport analysis based on the FLEXPART lagrangian model. The cross analysis of trace gas concentrations and transport pathways revealed 5 types of air masses: convective uplift of industrial and urban emissions, convective uplift of biogenic emissions, slow advection from Cotonou polluted plumes near the coast, meridional transport of upper tropospheric air from the subtropical barrier region, and meridional transport of Southern Hemisphere (SH biomass burning emissions. O₃/CO correlation plots and the correlation plots of H₂O₂ with a OH proxy revealed not only a control of the trace gas variability by transport processes but also significant photochemical reactivity in the mid- and upper troposphere. The study of four MCSs outflow showed contrasted chemical composition and air mass origins depending on the MCSs lifetime and latitudinal position. Favorables conditions for ozone

Potential impact of carbonaceous aerosol on the upper troposphere and lower stratosphere (UTLS) and precipitation during Asian summer monsoon in a global model simulation

KAUST Repository

Fadnavis, Suvarna; Kalita, Gayatry; Kumar, K. Ravi; Gasparini, Blaž; Li, Jui-Lin Frank

2017-01-01

The model simulation shows that boundary layer aerosols are transported into the monsoon anticyclone by the strong monsoon convection from the Bay of Bengal, southern slopes of the Himalayas and the South China Sea. Doubling of emissions of both BC and OC aerosols over Southeast Asia (10° S–50° N, 65–155° E) shows that lofted aerosols produce significant warming (0.6–1 K) over the Tibetan Plateau (TP) near 400–200 hPa and instability in the middle/upper troposphere. These aerosols enhance radiative heating rates (0.02–0.03 K day−1) near the tropopause. The enhanced carbonaceous aerosols alter aerosol radiative forcing (RF) at the surface by −4.74 ± 1.42 W m−2, at the top of the atmosphere (TOA) by +0.37 ± 0.26 W m−2 and in the atmosphere by +5.11 ± 0.83 W m−2 over the TP and Indo-Gangetic Plain region (15–35° N, 80–110° E). Atmospheric warming increases vertical velocities and thereby cloud ice in the upper troposphere. Aerosol induced anomalous warming over the TP facilitates the relative strengthening of the monsoon Hadley circulation and increases moisture inflow by strengthening the cross-equatorial monsoon jet. This increases precipitation amounts over India (1–4 mm day−1) and eastern China (0.2–2 mm day−1). These results are significant at the 99 % confidence level.

Overview and sample applications of SMILES and Odin-SMR retrievals of upper tropospheric humidity and cloud ice mass

Directory of Open Access Journals (Sweden)

P. Eriksson

2014-12-01

Full Text Available Retrievals of cloud ice mass and humidity from the Superconducting Submillimeter-Wave Limb-Emission Sounder (SMILES and the Odin-SMR (Sub-Millimetre Radiometer limb sounder are presented and example applications of the data are given. SMILES data give an unprecedented view of the diurnal variation of cloud ice mass. Mean regional diurnal cycles are reported and compared to some global climate models. Some improvements in the models regarding diurnal timing and relative amplitude were noted, but the models' mean ice mass around 250 hPa is still low compared to the observations. The influence of the ENSO (El Niño–Southern Oscillation state on the upper troposphere is demonstrated using 12 years of Odin-SMR data. The same retrieval scheme is applied for both sensors, and gives low systematic differences between the two data sets. A special feature of this Bayesian retrieval scheme, of Monte Carlo integration type, is that values are produced for all measurements but for some atmospheric states retrieved values only reflect a priori assumptions. However, this "all-weather" capability allows a direct statistical comparison to model data, in contrast to many other satellite data sets. Another strength of the retrievals is the detailed treatment of "beam filling" that otherwise would cause large systematic biases for these passive cloud ice mass retrievals. The main retrieval inputs are spectra around 635/525 GHz from tangent altitudes below 8/9 km for SMILES/Odin-SMR, respectively. For both sensors, the data cover the upper troposphere between 30° S and 30° N. Humidity is reported as both relative humidity and volume mixing ratio. The vertical coverage of SMILES is restricted to a single layer, while Odin-SMR gives some profiling capability between 300 and 150 hPa. Ice mass is given as the partial ice water path above 260 hPa, but for Odin-SMR ice water content, estimates are also provided. Besides a smaller contrast between most dry and wet

Modern air humidification in the tension field of hygiene and technology; Moderne Luftbefeuchtung im Spannungsfeld von Hygiene und Technik

Energy Technology Data Exchange (ETDEWEB)

Huester, R. [SCIENTICON Scientific Consulting, Rielasingen (Germany)

2006-07-01

The new methods of air conditioning must also guarantee sufficient air humidification in the supplied rooms. In order to avoid the humidified air being a special risk for diseases and allergies, the drinking water quality and humidification technology must be adjusted to each other. The use of water with a low content of alive or dead bacteria or cell components is as important as avoiding large magnitudes of aerosols, which access lungs or alveoli. (orig.)

How predictable is the northern hemisphere summer upper-tropospheric circulation?

Energy Technology Data Exchange (ETDEWEB)

Lee, June-Yi; Wang, Bin [University of Hawaii/IPRC, International Pacific Research Center, Honolulu, HI (United States); Ding, Q. [University of Washington, Department of Earth and Space Sciences and Quaternary Research Center, Seattle, WA (United States); Ha, K.J.; Ahn, J.B. [Pusan National University, Division of Earth Environmental System, Busan (Korea, Republic of); Kumar, A. [NCEP/CPC, Camp Springs, MD (United States); Stern, B. [Princeton University, NOAA/GFDL, Princeton, NJ (United States); Alves, O. [Bureau of Meteorology, Centre for Australia Weather and Climate Research (CAWCR), Melbourne, VIC (Australia)

2011-09-15

The retrospective forecast skill of three coupled climate models (NCEP CFS, GFDL CM2.1, and CAWCR POAMA 1.5) and their multi-model ensemble (MME) is evaluated, focusing on the Northern Hemisphere (NH) summer upper-tropospheric circulation along with surface temperature and precipitation for the 25-year period of 1981-2005. The seasonal prediction skill for the NH 200-hPa geopotential height basically comes from the coupled models' ability in predicting the first two empirical orthogonal function (EOF) modes of interannual variability, because the models cannot replicate the residual higher modes. The first two leading EOF modes of the summer 200-hPa circulation account for about 84% (35.4%) of the total variability over the NH tropics (extratropics) and offer a hint of realizable potential predictability. The MME is able to predict both spatial and temporal characteristics of the first EOF mode (EOF1) even at a 5-month lead (January initial condition) with a pattern correlation coefficient (PCC) skill of 0.96 and a temporal correlation coefficient (TCC) skill of 0.62. This long-lead predictability of the EOF1 comes mainly from the prolonged impacts of El Nino-Southern Oscillation (ENSO) as the EOF1 tends to occur during the summer after the mature phase of ENSO. The second EOF mode (EOF2), on the other hand, is related to the developing ENSO and also the interdecadal variability of the sea surface temperature over the North Pacific and North Atlantic Ocean. The MME also captures the EOF2 at a 5-month lead with a PCC skill of 0.87 and a TCC skill of 0.67, but these skills are mainly obtained from the zonally symmetric component of the EOF2, not the prominent wavelike structure, the so-called circumglobal teleconnection (CGT) pattern. In both observation and the 1-month lead MME prediction, the first two leading modes are accompanied by significant rainfall and surface air temperature anomalies in the continental regions of the NH extratropics. The MME

Aerosol indirect effect on tropospheric ozone via lightning

Science.gov (United States)

Yuan, T.; Remer, L. A.; Bian, H.; Ziemke, J. R.; Albrecht, R. I.; Pickering, K. E.; Oreopoulos, L.; Goodman, S. J.; Yu, H.; Allen, D. J.

2012-12-01

Tropospheric ozone (O3) is a pollutant and major greenhouse gas and its radiative forcing is still uncertain. The unresolved difference between modeled and observed natural background O3 concentrations is a key source of the uncertainty. Here we demonstrate remarkable sensitivity of lightning activity to aerosol loading with lightning activity increasing more than 30 times per unit of aerosol optical depth over our study area. We provide observational evidence that indicates the observed increase in lightning activity is caused by the influx of aerosols from a volcano. Satellite data analyses suggest O3 is increased as a result of aerosol-induced increase in lightning and lightning produced NOx. Model simulations with prescribed lightning change corroborate the satellite data analysis. This aerosol-O3 connection is achieved via aerosol increasing lightning and thus lightning produced nitrogen oxides. This aerosol-lightning-ozone link provides a potential physical mechanism that may account for a part of the model-observation difference in background O3 concentration. More importantly, O3 production increase from this link is concentrated in the upper troposphere, where O3 is most efficient as a greenhouse gas. Both of these implications suggest a stronger O3 historical radiative forcing. This introduces a new pathway, through which increasing in aerosols from pre-industrial time to present day enhances tropospheric O3 production. Aerosol forcing thus has a warming component via its effect on O3 production. Sensitivity simulations suggest that 4-8% increase of tropospheric ozone, mainly in the tropics, is expected if aerosol-lighting-ozone link is parameterized, depending on the background emission scenario. We note, however, substantial uncertainties remain on the exact magnitude of aerosol effect on tropospheric O3 via lightning. The challenges for obtaining a quantitative global estimate of this effect are also discussed. Our results have significant implications

Stratospheric Ozone Distribution and Tropospheric General Circulation: Interconnections in the UTLS Region

Science.gov (United States)

Barodka, S.; Krasovsky, A.; Shalamyansky, A.

2014-12-01

The height of the tropopause, which divided the stratosphere and the troposphere, is a result of two rival categories of processes: the tropospheric vertical convection and the radiative heating of the stratosphere resulting from the ozone cycle. Hence, it is natural that tropospheric and stratospheric phenomena can have effect each other in manifold processes of stratosphere-troposphere interactions. In the present study we focus our attention to the "top-down" side of the interaction: the impact of stratospheric ozone distribution on the features of tropospheric circulation and the associated weather patterns and regional climate conditions. We proceed from analyzes of the observational data performed at the A.I. Voeikov Main Geophysical Observatory, which suggest a distinct correlation between stratospheric ozone distribution, synoptic formations and air-masses boundaries in the upper troposphere and the temperature field of the lower stratosphere [1]. Furthermore, we analyze local features of atmospheric general circulation and stratospheric ozone distribution from the atmospheric reanalyses and general circulation model data, focusing our attention to instantaneous positions of subtropical and polar stationary atmospheric fronts, which define regional characteristics of the general circulation cells in the troposphere and separate global tropospheric air-masses, correspond to distinct meteorological regimes in the TOC field [2, 3]. We assume that by altering the tropopause height, stratospheric ozone-related processes can have an impact on the location of the stationary atmospheric fronts, thereby exerting influence on circulation processes in troposphere and lower stratosphere. For midlatitudes, the tropopause height controls the position of the polar stationary front, which has a direct impact on the trajectory of motion of active vortices on synoptic tropospheric levels, thereby controlling weather patterns in that region and the regional climate. This

Exergy Analysis of a Solar Humidification- Dehumidification Desalination Unit

OpenAIRE

Mohammed A. Elhaj; Jamal S. Yassin

2013-01-01

This paper presents the exergy analysis of a desalination unit using humidification-dehumidification process. Here, this unit is considered as a thermal system with three main components, which are the heating unit by using a solar collector, the evaporator or the humidifier, and the condenser or the dehumidifier. In these components the exergy is a measure of the quality or grade of energy and it can be destroyed in them. According to the second law of thermodynamics thi...

A feasibility and efficacy trial of a hand-held humidification device in patients undergoing radiotherapy for head and neck cancer.

Science.gov (United States)

Ghosh, Priyanka; Lazar, Ann A; Ryan, William R; Yom, Sue S

2017-08-01

This study aimed to evaluate the effects of warm-mist humidification during and after head and neck radiation therapy (HN RT) on quality of life (QOL), as measured by the M. D. Anderson Symptom Inventory-Head and Neck (MDASI-HN) HN score. A secondary aim was to compare QOL among compliers (≥60% of protocol-recommended usage) versus non-compliers. Twenty patients self-administered a hand-held, self-sterilizing humidification device for a recommended time of at least 15 min twice daily for 12 weeks. Patients completed the MDASI-HN instrument at RT start, after 6 weeks, and after 12 weeks. Compliance was reported weekly. The average HN score at baseline was 1.7 (SD = 1.8) and increased to 6.0 (SD = 1.6) after 6 weeks; this increase was much higher than anticipated and the primary endpoint could not be reached. However, compliers had an average of nearly two less HN symptoms (-1.8, 95% CI -4 to 0.2; p = 0.08) than non-compliers at 6 weeks and fewer symptoms at 12 weeks as well (-0.9, 95% CI -2.9 to 1.2; p = 0.39). The most common terms patients used to describe humidification were "helpful" and "soothing." Compliance with humidification during RT was associated with fewer reported HN symptoms and a strong trend to better QOL. Improvements were seen from compliance with occasional required use of a portable, inexpensive device. Our findings support continued efforts to reduce barriers to humidification, as an intervention that should be considered for standard HN RT clinical practice.

Effects of 1997-1998 El Nino on Tropospheric Ozone and Water Vapor

Science.gov (United States)

Chandra, S.; Ziemke, J. R.; Min, W.; Read, W. G.

1998-01-01

This paper analyzes the impact of the 1997-1998 El Nino on tropospheric column ozone and tropospheric water vapor derived respectively from the Total Ozone Mapping Spectrometer (TOMS) on Earth Probe and the Microwave Limb Scanning instrument on the Upper Atmosphere Research Satellite. The 1997-1998 El Nino, characterized by an anomalous increase in sea-surface temperature (SST) across the eastern and central tropical Pacific Ocean, is one of the strongest El Nino Southern Oscillation (ENSO) events of the century, comparable in magnitude to the 1982-1983 episode. The major impact of the SST change has been the shift in the convection pattern from the western to the eastern Pacific affecting the response of rain-producing cumulonimbus. As a result, there has been a significant increase in rainfall over the eastern Pacific and a decrease over the western Pacific and Indonesia. The dryness in the Indonesian region has contributed to large-scale burning by uncontrolled wildfires in the tropical rainforests of Sumatra and Borneo. Our study shows that tropospheric column ozone decreased by 4-8 Dobson units (DU) in the eastern Pacific and increased by about 10-20 DU in the western Pacific largely as a result of the eastward shift of the tropical convective activity as inferred from National Oceanic and Atmospheric Administration (NOAA) outgoing longwave radiation (OLR) data. The effect of this shift is also evident in the upper tropospheric water vapor mixing ratio which varies inversely as ozone (O3). These conclusions are qualitatively consistent with the changes in atmospheric circulation derived from zonal and vertical wind data obtained from the Goddard Earth Observing System data assimilation analyses. The changes in tropospheric column O3 during the course of the 1997-1998 El Nino appear to be caused by a combination of large-scale circulation processes associated with the shift in the tropical convection pattern and surface/boundary layer processes associated with

The effect of clouds on photolysis rates and ozone formation in the unpolluted troposphere

Science.gov (United States)

Thompson, A. M.

1984-01-01

The photochemistry of the lower atmosphere is sensitive to short- and long-term meteorological effects; accurate modeling therefore requires photolysis rates for trace gases which reflect this variability. As an example, the influence of clouds on the production of tropospheric ozone has been investigated, using a modification of Luther's two-stream radiation scheme to calculate cloud-perturbed photolysis rates in a one-dimensional photochemical transport model. In the unpolluted troposphere, where stratospheric inputs of odd nitrogen appear to represent the photochemical source of O3, strong cloud reflectance increases the concentration of NO in the upper troposphere, leading to greatly enhanced rates of ozone formation. Although the rate of these processes is too slow to verify by observation, the calculation is useful in distinguishing some features of the chemistry of regions of differing mean cloudiness.

Two-dimensional performance of MIPAS observation modes in the upper-troposphere/lower-stratosphere

Directory of Open Access Journals (Sweden)

M. Carlotti

2011-02-01

Full Text Available In this paper we analyze the performance of the three MIPAS (Michelson Interferometer for Passive Atmospheric Sounding observation modes that sound the Upper-Troposphere/Lower-Stratosphere (UT/LS region. The two-dimensional (2-D tomographic retrieval approach is assumed to derive the atmospheric field of geophysical parameters. For each observation mode we have calculated the 2-D distribution of the information load quantifier relative to the main MIPAS targets. The performance of the observation modes has been evaluated in terms of strength and spatial coverage of the information-load distribution along the full orbit. The indications of the information-load analysis has been validated with simulated retrievals based on the observational parameters of real orbits. In the simulation studies we have assessed the precision and the spatial (both horizontal and vertical resolution of the retrieval products. The performance of the three observation modes has been compared for the MIPAS main products in both the UT/LS and the extended altitude range. This study shows that the two observation modes that were specifically designed for the UT/LS region are actually competitive with the third one, designed for the whole stratosphere, up to altitudes that far exceed the UT/LS. In the UT/LS the performance of the two specific observation modes is comparable even if the best performance in terms of horizontal resolution is provided by the observation mode that was excluded by the European Space Agency (ESA from the current MIPAS duty cycle. This paper reports the first application of the information-load analysis and highlights the worthiness of this approach to make qualitative considerations about retrieval potential and selection of retrieval grid.

Experimental analysis of pressurised humidification tower for humid air gas turbine cycles. Part A: Experimental campaign

International Nuclear Information System (INIS)

Pedemonte, A.A.; Traverso, A.; Massardo, A.F.

2008-01-01

One of the most interesting methods of water introduction in a gas turbine circuit is represented by the humid air turbine cycle (HAT). In the HAT cycle, the humidification can be provided by a pressurised saturator (i.e. humidification tower or saturation tower), this solution being known to offer several attractive features. This part A is focused on an experimental study of a pressurised humidification tower, with structured packing inside. After a description of the test rig employed to carry out the measuring campaign, the results relating to the thermodynamic process are presented and discussed. The experimental campaign was carried out over 162 working points, covering a relatively wide range of possible operating conditions. Details about measured data are provided in the appendix. It is shown that the saturator's behaviour, in terms of air outlet humidity and temperature, is primarily driven by, in decreasing order of relevance, the inlet water temperature, the inlet water over inlet dry air mass flow ratio and the inlet air temperature. Finally, the exit relative humidity is shown to be consistently over 100%, which may be explained partially by measurement accuracy and droplet entrainment, and partially by the non-ideal behaviour of air-steam mixtures close to saturation

Humidification policies for mechanically ventilated intensive care patients and prevention of ventilator-associated pneumonia: a systematic review of randomized controlled trials.

Science.gov (United States)

Niël-Weise, B S; Wille, J C; van den Broek, P J

2007-04-01

The Dutch Working Party on Infection Prevention (WIP) aimed to determine whether certain humidification policies are better than others in terms of prevention of ventilator-associated pneumonia (VAP) in mechanically ventilated intensive care unit (ICU) patients. Publications were retrieved by a systematic search of Medline and the Cochrane Library up to February 2006. All (quasi-) randomized trials and systematic reviews/meta-analyses comparing humidification methods in ventilated ICU patients were selected. Two reviewers independently assessed trial quality and extracted data. If the data was incomplete, clarification was sought from original authors and used to calculate the relative risk of VAP. Data for VAP were combined in the analysis, where appropriate, using a random-effects model. Ten trials were included in the review. In general, the quality of the trials and the way they were reported were unsatisfactory. The results did not show any benefit from specific humidification techniques in terms of reducing VAP. WIP do not recommend either passive or active humidifiers to prevent VAP, nor the type of passive humidifiers to be used. Regarding active humidification, WIP recommends using heated wire circuits. This is due to the theoretical consideration that less condensate reduces colonization and subsequent risk of spread throughout an ICU when condensate is removed.

Closed-Loop Control of Humidification for Artifact Reduction in Capacitive ECG Measurements.

Science.gov (United States)

Leicht, Lennart; Eilebrecht, Benjamin; Weyer, Soren; Leonhardt, Steffen; Teichmann, Daniel

2017-04-01

Recording biosignals without the need for direct skin contact offers new opportunities for ubiquitous health monitoring. Electrodes with capacitive coupling have been shown to be suitable for the monitoring of electrical potentials on the body surface, in particular ECG. However, due to triboelectric charge generation and motion artifacts, signal and thus diagnostic quality is inferior to galvanic coupling. Active closed-loop humidification of capacitive electrodes is proposed in this work as a new concept to improve signal quality. A capacitive ECG recording system integrated into a common car seat is presented. It can regulate the micro climate at the interface of electrode and patient by actively dispensing water vapour and monitoring humidity in a closed-loop approach. As a regenerative water reservoir, silica gel is used. The system was evaluated with respect to subjective and objective ECG signal quality. Active humidification was found to have a significant positive effect in case of previously poor quality. Also, it had no diminishing effect in case of already good signal quality.

Spectropolarimetric Measurements of Scattered Sunlight in the Huggins Bands: Retrieval of Tropospheric Ozone Profiles

Science.gov (United States)

Fu, D.; Sander, S. P.; Stutz, J.; Pongetti, T. J.; Yung, Y. L.; Wong, M.; Natraj, V.; Li, K.; Shia, R.

2009-12-01

Ozone concentrations in the troposphere have increased over the past century as a result of anthropogenic emissions of NOx and volatile organic compounds. In addition to being harmful to human health and plant life, ozone is an important greenhouse gas, especially in the middle and upper troposphere. Therefore, accurate monitoring of tropospheric ozone vertical distributions is crucial for a better understanding of air quality and climate change. Simulations of vector radiative transfer in the near ultraviolet region have shown that tropospheric ozone profiles can be retrieved using polarization measurements. However, to date there has been no experimental test of this method. A new compact, portable spectropolarimeter has been built for atmospheric remote sensing. The first comprehensive description of the configuration and performance of this instrument for ground-based operation is provided and sample atmospheric scattered sunlight spectra are shown. Using optimal estimation retrieval theory we study the information content of polarization spectra in the Huggins band and uncertainties in the retrieval associated with the measurement parameters, such as aerosol scattering.

Chemical and aerosol characterisation of the troposphere over West Africa during the monsoon period as part of AMMA

Directory of Open Access Journals (Sweden)

C. E. Reeves

2010-08-01

Full Text Available During June, July and August 2006 five aircraft took part in a campaign over West Africa to observe the aerosol content and chemical composition of the troposphere and lower stratosphere as part of the African Monsoon Multidisciplinary Analysis (AMMA project. These are the first such measurements in this region during the monsoon period. In addition to providing an overview of the tropospheric composition, this paper provides a description of the measurement strategy (flights performed, instrumental payloads, wing-tip to wing-tip comparisons and points to some of the important findings discussed in more detail in other papers in this special issue.

The ozone data exhibits an "S" shaped vertical profile which appears to result from significant losses in the lower troposphere due to rapid deposition to forested areas and photochemical destruction in the moist monsoon air, and convective uplift of ozone-poor air to the upper troposphere. This profile is disturbed, particularly in the south of the region, by the intrusions in the lower and middle troposphere of air from the southern hemisphere impacted by biomass burning. Comparisons with longer term data sets suggest the impact of these intrusions on West Africa in 2006 was greater than in other recent wet seasons. There is evidence for net photochemical production of ozone in these biomass burning plumes as well as in urban plumes, in particular that from Lagos, convective outflow in the upper troposphere and in boundary layer air affected by nitrogen oxide emissions from recently wetted soils. This latter effect, along with enhanced deposition to the forested areas, contributes to a latitudinal gradient of ozone in the lower troposphere. Biogenic volatile organic compounds are also important in defining the composition both for the boundary layer and upper tropospheric convective outflow.

Mineral dust was found to be the most abundant and ubiquitous aerosol type in the

Assessing environmental performance of humidification technology used in supply of fresh fruit and vegetables

DEFF Research Database (Denmark)

Fabbri, Serena; Owsianiak, Mikolaj

-harvest losses of fruit and vegetables. Humidifiers release a fine mist thereby reducing the difference in water vapour pressure at the surface of the fruit or vegetable and in the air, preventing dry-out of fruits and deterioration. In addition, humidification provides cooling as a result of the evaporation...... scenarios considered strawberries, flat peaches, asparagus, and table grapes. The results show that the technology has the potential to reduce life cycle environmental impacts, provided that it allows reducing food loss in the post-harvest. When compared to the conventional supply chain of lettuce without...... humidification, the impact scores are reduced on average by 2.6, 6.0 and 7.4% when the total losses of the supply chain are decreased by 2, 5 and 6%, respectively (corresponding to low, medium and high efficiency of the technology). This is true for all impact categories, except resource depletion which...

Evidence of a tropospheric aerosol backscatter background mode

Science.gov (United States)

Rothermel, Jeffry; Bowdle, David A.; Vaughan, J. Michael; Post, Madison J.

1989-01-01

Vertical profiles of atmospheric aerosol backscatter coefficients at 10.6 microns obtained with airborne and ground-based lidar are compared. Both sets of profiles show a high frequency of occurrence of low backscatter over a limited range of values in the middle and upper troposphere. It is suggested that this narrow range indicates a ubiquitous background mode for atmospheric backscatter around the globe. Implications of such a mode for global scale aerosol models and for the design of satellite-borne lidar-based sensors are discussed.

Class and Home Problems: Humidification, a True "Home" Problem for p. Chemical Engineer

Science.gov (United States)

Condoret, Jean-Stephane

2012-01-01

The problem of maintaining hygrothermal comfort in a house is addressed using the chemical engineer's toolbox. A simple dynamic modelling proved to give a good description of the humidification of the house in winter, using a domestic humidifier. Parameters of the model were identified from a simple experiment. Surprising results, especially…

Retrieval of water vapor vertical distributions in the upper troposphere and the lower stratosphere from SCIAMACHY limb measurements

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A. Rozanov

2011-05-01

Full Text Available This study describes the retrieval of water vapor vertical distributions in the upper troposphere and lower stratosphere (UTLS altitude range from space-borne observations of the scattered solar light made in limb viewing geometry. First results using measurements from SCIAMACHY (Scanning Imaging Absorption spectroMeter for Atmospheric CHartographY aboard ENVISAT (Environmental Satellite are presented here. In previous publications, the retrieval of water vapor vertical distributions has been achieved exploiting either the emitted radiance leaving the atmosphere or the transmitted solar radiation. In this study, the scattered solar radiation is used as a new source of information on the water vapor content in the UTLS region. A recently developed retrieval algorithm utilizes the differential absorption structure of the water vapor in 1353–1410 nm spectral range and yields the water vapor content in the 11–25 km altitude range. In this study, the retrieval algorithm is successfully applied to SCIAMACHY limb measurements and the resulting water vapor profiles are compared to in situ balloon-borne observations. The results from both satellite and balloon-borne instruments are found to agree typically within 10 %.

Secondary ozone peaks in the troposphere over the Himalayas

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N. Ojha

2017-06-01

Full Text Available Layers with strongly enhanced ozone concentrations in the middle–upper troposphere, referred to as secondary ozone peaks (SOPs, have been observed in different regions of the world. Here we use the global ECHAM5/MESSy atmospheric chemistry model (EMAC to (i investigate the processes causing SOPs, (ii explore both their frequency of occurrence and seasonality, and (iii assess their effects on the tropospheric ozone budget over the Himalayas. The vertical profiles of potential vorticity (PV and a stratospheric ozone tracer (O3s in EMAC simulations, in conjunction with the structure of SOPs, suggest that SOPs over the Himalayas are formed by stratosphere-to-troposphere transport (STT of ozone. The spatial distribution of O3s further shows that such effects are in general most pronounced in the northern part of India. Model simulated ozone distributions and backward air trajectories show that ozone rich air masses, associated with STT, originate as far as northern Africa and the North Atlantic Ocean, the Middle East, as well as in nearby regions in Afghanistan and Pakistan, and are rapidly (within 2–3 days transported to the Himalayas. Analysis of a 15-year (2000–2014 EMAC simulation shows that the frequency of SOPs is highest during the pre-monsoon season (e.g. 11 % of the time in May, while no intense SOP events are found during the July–October period. The SOPs are estimated to enhance the tropospheric column ozone (TCO over the central Himalayas by up to 21 %.

Emgas pioneers gas conditioning by humidification

Energy Technology Data Exchange (ETDEWEB)

de Winton, C

1975-03-01

As a first solution to any problems of serious joint leaking in low- and medium-pressure distribution networks, East Midlands Gas is using gas conditioning by steam or water injection and/or oil fogging. The project has been conceived on a sufficiently large scale to take in the whole area of supply; plans call for completion over a period of 7 yr. Emgas has based its humidification process on a positive control system, first and foremost to avoid certain serious pitfalls which can befall the casual injection of steam or water into a gas main. The control system used has been built around the Foxboro Dewcel, a thin-walled metal socket covered with a woven glass tape impregnated with lithium chloride. A 25-V ac source is connected to a pair of gold wires wound around the tape.

NOAA Climate Data Record for Mean Layer Temperature (Upper Troposphere & Lower Stratosphere) from UCAR, Version 2

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The Temperatures of Troposphere / Stratosphere (TTS) (AMSU channel 7 and MSU channel 3) CDR is generated by using National Oceanic and Atmospheric Administration...

Performance analysis of a novel heat pump type air conditioner coupled with a liquid dehumidification/humidification cycle

International Nuclear Information System (INIS)

Cai, Dehua; Qiu, Chengbo; Zhang, Jiazheng; Liu, Yue; Liang, Xiao; He, Guogeng

2017-01-01

Graphical abstract: Cycle performance of a small scale heat pump type air conditioner coupled with a liquid desiccant/humidification cycle has been theoretically and experimentally evaluated by the present study. The liquid desiccant and humidification cycle is driven by the exhaust heat of the compressor. LDAC not only greatly improves the indoor air quality by controlling the humidity and temperature independently, but also decrease the electrical energy consumption of the traditional air conditioner. Parametric analysis on cycle performance of the present cycle based on both theoretical and experimental methods are carried out. - Highlights: • Hybrid cycle consists of refrigeration cycle and liquid desiccant cycle is proposed. • Liquid desiccant cycle is driven by the compressor exhaust heat. • Theoretical and experimental studies on cycle performance are provided. • Energy consumption decreases about 22.64% compared with the conventional one. - Abstract: In recent years, liquid desiccant air-conditioning system (LDAC) has shown a great potential alternative to the conventional vapor compression systems. LDAC not only greatly improves the indoor air quality by controlling the humidity and temperature independently, but also deceases the electrical energy consumption of the conventional air conditioner. In this work, the liquid desiccant and humidification cycle is driven by the exhaust heat of the compressor. Cycle performance of a small-scale heat pump type air conditioner coupled with a liquid desiccant/humidification cycle has been theoretically and experimentally evaluated by the present study. Parametric analysis on cycle performance of the present cycle is carried out through both theoretical and experimental methods, and lithium chloride aqueous solution is used as the working fluid of the solution cycle. The thermodynamic analysis results show that while the evaporating temperature of the present cycle increases to 15 °C, the energy consumption

Effectiveness of Humidification with Heat and Moisture Exchanger-booster in Tracheostomized Patients.

Science.gov (United States)

Gonzalez, Isabel; Jimenez, Pilar; Valdivia, Jorge; Esquinas, Antonio

2017-08-01

The two most commonly used types of humidifiers are heated humidifiers and heat and moisture exchange humidifiers. Heated humidifiers provide adequate temperature and humidity without affecting the respiratory pattern, but overdose can cause high temperatures and humidity resulting in condensation, which increases the risk of bacteria in the circuit. These devices are expensive. Heat and moisture exchanger filter is a new concept of humidification, increasing the moisture content in inspired gases. This study aims to determine the effectiveness of the heat and moisture exchanger (HME)-Booster system to humidify inspired air in patients under mechanical ventilation. We evaluated the humidification provided by 10 HME-Booster for tracheostomized patients under mechanical ventilation using Servo I respirators, belonging to the Maquet company and Evita 4. There was an increase in the inspired air humidity after 1 h with the humidifier. The HME-Booster combines the advantages of heat and moisture exchange minimizing the negatives. It increases the amount of moisture in inspired gas in mechanically ventilated tracheostomized patients. It is easy and safe to use. The type of ventilator used has no influence on the result.

Phase 3 Trial of Domiciliary Humidification to Mitigate Acute Mucosal Toxicity During Radiation Therapy for Head-and-Neck Cancer: First Report of Trans Tasman Radiation Oncology Group (TROG) 07.03 RadioHUM Study

International Nuclear Information System (INIS)

Macann, Andrew; Fua, Tsien; Milross, Chris G.; Porceddu, Sandro V.; Penniment, Michael; Wratten, Chris; Krawitz, Hedley; Poulsen, Michael; Tang, Colin I.; Morton, Randall P.; Hay, K. David; Thomson, Vicki; Bell, Melanie L.; King, Madeleine T.; Fraser-Browne, Carol L.; Hockey, Hans-Ulrich P.

2014-01-01

Purpose: To assess the impact of domicile-based humidification on symptom burden during radiation therapy (RT) for head-and-neck (H and N) cancer. Methods and Materials: From June 2007 through June 2011, 210 patients with H and N cancer receiving RT were randomized to either a control arm or to receive humidification using the Fisher and Paykel Healthcare MR880 humidifier. Humidification commenced on day 1 of RT and continued until Common Terminology Criteria for Adverse Events (CTCAE), version 3.0, clinical mucositis (CMuc) grade ≤1 occurred. Forty-three patients (42%) met a defined benchmark for humidification compliance and contributed to per protocol (PP) analysis. Acute toxicities, hospitalizations, and feeding tube events were recorded prospectively. The McMaster University Head and Neck Radiotherapy Questionnaire (HNRQ) was used for patient-reported outcomes. The primary endpoint was area under the curve (AUC) for CMuc grade ≥2. Results: There were no significant differences in AUC for CMuc ≥2 between the 2 arms. Humidification patients had significantly fewer days in hospital (P=.017). In compliant PP patients, the AUC for CTCAE functional mucositis score (FMuc) ≥2 was significantly reduced (P=.009), and the proportion who never required a feeding tube was significantly greater (P=.04). HNRQ PP analysis estimates also in the direction favoring humidification with less symptom severity, although differences at most time points did not reach significance. Conclusions: TROG 07.03 has provided efficacy signals consistent with a role for humidification in reducing symptom burden from mucositis, but the influence of humidification compliance on the results moderates recommendations regarding its practical utility

Phase 3 Trial of Domiciliary Humidification to Mitigate Acute Mucosal Toxicity During Radiation Therapy for Head-and-Neck Cancer: First Report of Trans Tasman Radiation Oncology Group (TROG) 07.03 RadioHUM Study

Energy Technology Data Exchange (ETDEWEB)

Macann, Andrew, E-mail: amacann@adhb.govt.nz [Department of Radiation Oncology, Auckland City Hospital, Auckland (New Zealand); Fua, Tsien [Department of Radiation Oncology, Peter MacCallum Cancer Centre, East Melbourne, Victoria (Australia); Milross, Chris G. [Department of Radiation Oncology, Royal Prince Alfred Hospital, Camperdown, New South Wales (Australia); Porceddu, Sandro V. [Oncology Services, Princess Alexandra Hospital, Woolloongabba, Queensland (Australia); Penniment, Michael [Radiation Oncology, Royal Adelaide Hospital, Adelaide, South Australia (Australia); Wratten, Chris [Radiation Oncology, Calvary Mater Newcastle, Waratah, New South Wales (Australia); Krawitz, Hedley [Department of Radiation Oncology, Auckland City Hospital, Auckland (New Zealand); Poulsen, Michael [Department of Radiation Oncology, Radiation Oncology Mater Centre, South Brisbane, Queensland (Australia); Tang, Colin I. [Department of Radiation Oncology, Sir Charles Gairdner Hospital, Nedlands, Western Australia (Australia); Morton, Randall P. [Department of Otorhinolaryngology, Middlemore Hospital, Otahuhu, Auckland (New Zealand); Hay, K. David [Department of Oral Health, Auckland City Hospital, Auckland (New Zealand); Thomson, Vicki [Department of Otorhinolaryngology, Auckland City Hospital, Auckland (New Zealand); Bell, Melanie L.; King, Madeleine T. [Psycho-oncology Cooperative Research Group, Univerity of Sydney, Sydney, New South Wales (Australia); Fraser-Browne, Carol L. [Adult Oncology Research Centre, Auckland City Hospital, Auckland (New Zealand); Hockey, Hans-Ulrich P. [Biometrics Matters Ltd, Hamilton (New Zealand)

2014-03-01

Purpose: To assess the impact of domicile-based humidification on symptom burden during radiation therapy (RT) for head-and-neck (H and N) cancer. Methods and Materials: From June 2007 through June 2011, 210 patients with H and N cancer receiving RT were randomized to either a control arm or to receive humidification using the Fisher and Paykel Healthcare MR880 humidifier. Humidification commenced on day 1 of RT and continued until Common Terminology Criteria for Adverse Events (CTCAE), version 3.0, clinical mucositis (CMuc) grade ≤1 occurred. Forty-three patients (42%) met a defined benchmark for humidification compliance and contributed to per protocol (PP) analysis. Acute toxicities, hospitalizations, and feeding tube events were recorded prospectively. The McMaster University Head and Neck Radiotherapy Questionnaire (HNRQ) was used for patient-reported outcomes. The primary endpoint was area under the curve (AUC) for CMuc grade ≥2. Results: There were no significant differences in AUC for CMuc ≥2 between the 2 arms. Humidification patients had significantly fewer days in hospital (P=.017). In compliant PP patients, the AUC for CTCAE functional mucositis score (FMuc) ≥2 was significantly reduced (P=.009), and the proportion who never required a feeding tube was significantly greater (P=.04). HNRQ PP analysis estimates also in the direction favoring humidification with less symptom severity, although differences at most time points did not reach significance. Conclusions: TROG 07.03 has provided efficacy signals consistent with a role for humidification in reducing symptom burden from mucositis, but the influence of humidification compliance on the results moderates recommendations regarding its practical utility.

Phase 3 trial of domiciliary humidification to mitigate acute mucosal toxicity during radiation therapy for head-and-neck cancer: first report of Trans Tasman Radiation Oncology Group (TROG) 07.03 RadioHUM study.

Science.gov (United States)

Macann, Andrew; Fua, Tsien; Milross, Chris G; Porceddu, Sandro V; Penniment, Michael; Wratten, Chris; Krawitz, Hedley; Poulsen, Michael; Tang, Colin I; Morton, Randall P; Hay, K David; Thomson, Vicki; Bell, Melanie L; King, Madeleine T; Fraser-Browne, Carol L; Hockey, Hans-Ulrich P

2014-03-01

To assess the impact of domicile-based humidification on symptom burden during radiation therapy (RT) for head-and-neck (H&N) cancer. From June 2007 through June 2011, 210 patients with H&N cancer receiving RT were randomized to either a control arm or to receive humidification using the Fisher & Paykel Healthcare MR880 humidifier. Humidification commenced on day 1 of RT and continued until Common Terminology Criteria for Adverse Events (CTCAE), version 3.0, clinical mucositis (CMuc) grade ≤1 occurred. Forty-three patients (42%) met a defined benchmark for humidification compliance and contributed to per protocol (PP) analysis. Acute toxicities, hospitalizations, and feeding tube events were recorded prospectively. The McMaster University Head and Neck Radiotherapy Questionnaire (HNRQ) was used for patient-reported outcomes. The primary endpoint was area under the curve (AUC) for CMuc grade ≥2. There were no significant differences in AUC for CMuc ≥2 between the 2 arms. Humidification patients had significantly fewer days in hospital (P=.017). In compliant PP patients, the AUC for CTCAE functional mucositis score (FMuc) ≥2 was significantly reduced (P=.009), and the proportion who never required a feeding tube was significantly greater (P=.04). HNRQ PP analysis estimates also in the direction favoring humidification with less symptom severity, although differences at most time points did not reach significance. TROG 07.03 has provided efficacy signals consistent with a role for humidification in reducing symptom burden from mucositis, but the influence of humidification compliance on the results moderates recommendations regarding its practical utility. Copyright © 2014 Elsevier Inc. All rights reserved.

Oxygenated Organic Chemicals in the Pacific Troposphere: Distribution, Sources and Chemistry

Science.gov (United States)

Singh, Hanwant B.; Salas, L.; Chatfield, R.; Czech, E.; Fried, A.; Evans, M.; Jacob, D. J.; Blake, D.; Heikes, B.; Talbot, R.

2003-01-01

Airborne measurements of a large number of oxygenated organic chemicals (Oxorgs) were carried out in the Pacific troposphere (0.1-12 km) in the Spring of 2001 (Feb. 24-April 10). Specifically these measuremen ts included acetone, methylethyl ketone (MEK), methanol, ethanol, ace taldehyde, propionaldehyde, PANS, and organic nitrates. Complementary measurements of formaldehyde, organic peroxides, and tracers were al so available. Ox-orgs were abundant in the clean troposphere and were greatly enhanced in the outflow regions from Asia. Their mixing ratios were typically highest in the lower troposphere and declined toward s the upper troposphere and the lowermost stratosphere. Their total a bundance (Ox-orgs) significantly exceeded that of NMHC (C2-C8 NMHC). A comparison of these data with observations collected some seven yea rs earlier (Feb.-March, 1994), did not reveal any significant changes . Throughout the troposphere mixing ratios of Ox-orgs were strongly c orrelated with each other as well as with tracers of fossil and bioma sshiof'uel combustion. Analysis of the relative enhancement of selected Oxorgs with respect to CH3Cl and CO in twelve sampled plumes, origi nating from fires, is used to assess their primary and secondary sour ces from biomass combustion. The composition of these plumes also ind icates a large shift of reactive nitrogen into the PAN reservoir ther eby limiting ozone formation. The Harvard 3-D photochemical model, th at uses state of the art chemistry and source information, is used to compare simulated and observed mixing ratios of selected species. A 1 -D model is used to explore the chemistry of aldehydes. These results will be presented.

The global warming potential of methane reassessed with combined stratosphere and troposphere chemistry

Science.gov (United States)

Holmes, C. D.; Archibald, A. T.; Eastham, S. D.; Søvde, O. A.

2017-12-01

Methane is a direct and indirect greenhouse gas. The direct greenhouse effect comes from the radiation absorbed and emitted by methane itself. The indirect greenhouse effect comes from radiatively active gases that are produced during methane oxidation: principally O3, H2O, and CO2. Methane also suppresses tropospheric OH, which indirectly affects numerous greenhouses gases and aerosols. Traditionally, the methane global warming potential (GWP) has included the indirect effects on tropospheric O3 and OH and stratospheric H2O, with these effects estimated independently from unrelated tropospheric and stratospheric chemistry models and observations. Using this approach the CH4 is about 28 over 100 yr (without carbon cycle feedbacks, IPCC, 2013). Here we present a comprehensive analysis of the CH4 GWP in several 3-D global atmospheric models capable of simulating both tropospheric and stratospheric chemistry (GEOS-Chem, Oslo CTM3, UKCA). This enables us to include, for the first time, the indirect effects of CH4 on stratospheric O3 and stratosphere-troposphere coupling. We diagnose the GWP from paired simulations with and without a 5% perturbation to tropospheric CH4 concentrations. Including stratospheric chemistry nearly doubles the O3 contribution to CH4 GWP because of O3 production in the lower stratosphere and because CH4 inhibits Cl-catalyzed O3 loss in the upper stratosphere. In addition, stratosphere-troposphere coupling strengthens the chemical feedback on its own lifetime. In the stratosphere, this feedback operates by a CH4 perturbation thickening the stratospheric O3 layer, which impedes UV-driven OH production in the troposphere and prolongs the CH4 lifetime. We also quantify the impact of CH4-derived H2O on the stratospheric HOx cycles but these effects are small. Combining all of the above, these models suggest that the 100-yr GWP of CH4 is over 33.5, a 20% increase over the latest IPCC assessment.

Poleward upgliding Siberian atmospheric rivers over sea ice heat up Arctic upper air.

Science.gov (United States)

Komatsu, Kensuke K; Alexeev, Vladimir A; Repina, Irina A; Tachibana, Yoshihiro

2018-02-13

We carried out upper air measurements with radiosondes during the summer over the Arctic Ocean from an icebreaker moving poleward from an ice-free region, through the ice edge, and into a region of thick ice. Rapid warming of the Arctic is a significant environmental issue that occurs not only at the surface but also throughout the troposphere. In addition to the widely accepted mechanisms responsible for the increase of tropospheric warming during the summer over the Arctic, we showed a new potential contributing process to the increase, based on our direct observations and supporting numerical simulations and statistical analyses using a long-term reanalysis dataset. We refer to this new process as "Siberian Atmospheric Rivers (SARs)". Poleward upglides of SARs over cold air domes overlying sea ice provide the upper atmosphere with extra heat via condensation of water vapour. This heating drives increased buoyancy and further strengthens the ascent and heating of the mid-troposphere. This process requires the combination of SARs and sea ice as a land-ocean-atmosphere system, the implication being that large-scale heat and moisture transport from the lower latitudes can remotely amplify the warming of the Arctic troposphere in the summer.

The chemical effects on the summertime ozone in the upper troposphere and lower stratosphere over the Tibetan Plateau and the South Asian monsoon region

Science.gov (United States)

Gu, Yixuan; Liao, Hong; Xu, Jianming; Zhou, Guangqiang

2018-01-01

We use the global three-dimensional Goddard Earth Observing System chemical transport model with the Universal tropospheric-stratospheric Chemistry eXtension mechanism to examine the contributions of the chemical processes to summertime O3 in the upper troposphere and lower stratosphere (UTLS) over the Tibetan Plateau and the South Asian monsoon region (TP/SASM). Simulated UTLS O3 concentrations are evaluated by comparisons with Microwave Limb Sounder products and net chemical production of O3 (NPO3) are evaluated by comparisons with model results in previous studies. Simulations show that the chemical processes lead to an increase in O3 concentration, which is opposite to the effect of O3 transport in the UTLS over the TP/SASM region throughout the boreal summer. NPO3 in UTLS over the TP/SASM region is the largest in summer. Elevated values (0.016-0.020 Tg year-1) of the seasonal mean NPO3 are simulated to locate at 100 hPa in the TP/SASM region, where the mixing ratios of O3 are low and those of O3 precursors (NO x , VOCs, and CO) are high. The high concentrations of O3 precursors (NO x , VOCs, and CO) together with the active photochemical reactions of NO2 in the UTLS over the TP/SASM region during summertime could be important reasons for the enhancement of {NP}_{{{O}3 }} over the studied region.

Ozone sonde cell current measurements and implications for observations of near-zero ozone concentrations in the tropical upper troposphere

Directory of Open Access Journals (Sweden)

H. Vömel

2010-04-01

Full Text Available Laboratory measurements of the Electrochemical Concentration Cell (ECC ozone sonde cell current using ozone free air as well as defined amounts of ozone reveal that background current measurements during sonde preparation are neither constant as a function of time, nor constant as a function of ozone concentration. Using a background current, measured at a defined timed after exposure to high ozone may often overestimate the real background, leading to artificially low ozone concentrations in the upper tropical troposphere, and may frequently lead to operator dependent uncertainties. Based on these laboratory measurements an improved cell current to partial pressure conversion is proposed, which removes operator dependent variability in the background reading and possible artifacts in this measurement. Data from the Central Equatorial Pacific Experiment (CEPEX have been reprocessed using the improved background treatment based on these laboratory measurements. In the reprocessed data set near-zero ozone events no longer occur. At Samoa, Fiji, Tahiti, and San Cristóbal, nearly all near-zero ozone concentrations occur in soundings with larger background currents. To a large extent, these events are no longer observed in the reprocessed data set using the improved background treatment.

UV Raman lidar measurements of relative humidity for the characterization of cirrus cloud microphysical properties

Directory of Open Access Journals (Sweden)

G. Masiello

2009-11-01

Full Text Available Raman lidar measurements performed in Potenza by the Raman lidar system BASIL in the presence of cirrus clouds are discussed. Measurements were performed on 6 September 2004 in the frame of the Italian phase of the EAQUATE Experiment.

The major feature of BASIL is represented by its capability to perform high-resolution and accurate measurements of atmospheric temperature and water vapour, and consequently relative humidity, both in daytime and night-time, based on the application of the rotational and vibrational Raman lidar techniques in the UV. BASIL is also capable to provide measurements of the particle backscatter and extinction coefficient, and consequently lidar ratio (at the time of these measurements, only at one wavelength, which are fundamental to infer geometrical and microphysical properties of clouds.

A case study is discussed in order to assess the capability of Raman lidars to measure humidity in presence of cirrus clouds, both below and inside the cloud. While air inside the cloud layers is observed to be always under-saturated with respect to water, both ice super-saturation and under-saturation conditions are found inside these clouds. Upper tropospheric moistening is observed below the lower cloud layer.

The synergic use of the data derived from the ground based Raman Lidar and of spectral radiances measured by the NAST-I Airborne Spectrometer allows the determination of the temporal evolution of the atmospheric cooling/heating rates due to the presence of the cirrus cloud.

Lidar measurements beneath the cirrus cloud layer have been interpreted using a 1-D cirrus cloud model with explicit microphysics. The 1-D simulations indicate that sedimentation-moistening has contributed significantly to the moist anomaly, but other mechanisms are also contributing. This result supports the hypothesis that the observed mid-tropospheric humidification is a real feature which is

Source attribution of tropospheric ozone

Science.gov (United States)

Butler, T. M.

2015-12-01

Tropospheric ozone is a harmful pollutant with adverse effects on human health and ecosystems. As well as these effects, tropospheric ozone is also a powerful greenhouse gas, with an anthropogenic radiative forcing one quarter of that of CO2. Along with methane and atmospheric aerosol, tropospheric ozone belongs to the so-called Short Lived Climate forcing Pollutants, or SLCP. Recent work has shown that efforts to reduce concentrations of SLCP in the atmosphere have the potential to slow the rate of near-term climate change, while simultaneously improving public health and reducing crop losses. Unlike many other SLCP, tropospehric ozone is not directly emitted, but is instead influenced by two distinct sources: transport of air from the ozone-rich stratosphere; and photochemical production in the troposphere from the emitted precursors NOx (oxides of nitrogen), CO (Carbon Monoxide), and VOC (volatile organic compounds, including methane). Better understanding of the relationship between ozone production and the emissions of its precursors is essential for the development of targeted emission reduction strategies. Several modeling methods have been employed to relate the production of tropospheric ozone to emissions of its precursors; emissions perturbation, tagging, and adjoint sensitivity methods all deliver complementary information about modelled ozone production. Most studies using tagging methods have focused on attribution of tropospheric ozone production to emissions of NOx, even though perturbation methods have suggested that tropospheric ozone is also sensitive to VOC, particularly methane. In this study we describe the implementation into a global chemistry-climate model of a scheme for tagging emissions of NOx and VOC with an arbitrary number of labels, which are followed through the chemical reactions of tropospheric ozone production in order to perform attribution of tropospehric ozone to its emitted precursors. Attribution is performed to both

Humidification performance of humidifying devices for tracheostomized patients with spontaneous breathing: a bench study.

Science.gov (United States)

Chikata, Yusuke; Oto, Jun; Onodera, Mutsuo; Nishimura, Masaji

2013-09-01

Heat and moisture exchangers (HMEs) are commonly used for humidifying respiratory gases administered to mechanically ventilated patients. While they are also applied to tracheostomized patients with spontaneous breathing, their performance in this role has not yet been clarified. We carried out a bench study to investigate the effects of spontaneous breathing parameters and oxygen flow on the humidification performance of 11 HMEs. We evaluated the humidification provided by 11 HMEs for tracheostomized patients, and also by a system delivering high-flow CPAP, and an oxygen mask with nebulizer heater. Spontaneous breathing was simulated with a mechanical ventilator, lung model, and servo-controlled heated humidifier at tidal volumes of 300, 500, and 700 mL, and breathing frequencies of 10 and 20 breaths/min. Expired gas was warmed to 37°C. The high-flow CPAP system was set to deliver 15, 30, and 45 L/min. With the 8 HMEs that were equipped with ports to deliver oxygen, and with the high-flow CPAP system, measurements were taken when delivering 0 and 3 L/min of dry oxygen. After stabilization we measured the absolute humidity (AH) of inspired gas with a hygrometer. AH differed among HMEs applied to tracheostomized patients with spontaneous breathing. For all the HMEs, as tidal volume increased, AH decreased. At 20 breaths/min, AH was higher than at 10 breaths/min. For all the HMEs, when oxygen was delivered, AH decreased to below 30 mg/L. With an oxygen mask and high-flow CPAP, at all settings, AH exceeded 30 mg/L. None of the HMEs provided adequate humidification when supplemental oxygen was added. In the ICU, caution is required when applying HME to tracheostomized patients with spontaneous breathing, especially when supplemental oxygen is required.

Tropospheric aerosol backscatter background mode at CO2 wavelengths

Science.gov (United States)

Rothermel, Jeffry; Bowdle, David A.; Menzies, Robert T.; Post, Madison J.; Vaughan, J. Michael

1989-01-01

A comparison is made between three climatologies of backscatter measurements in the troposphere and lower stratosphere at CO2 wavelengths. These were obtained from several locations using ground-based and airborne lidar systems. All three measurement sets show similar features, specifically, a high frequency of occurrence of low backscatter over a limited range of values in the middle and upper atmosphere (the 'background mode'). This background mode is important for the design and performance simulation of the prospective satellite sensors that rely on atmospheric aerosols as scattering targets.

Impact of the water symmetry factor on humidification and cooling strategies for PEM fuel cell stacks

Energy Technology Data Exchange (ETDEWEB)

Picot, D; Metkemeijer, R; Bezian, J J; Rouveyre, L [Centre d` Energetique, Ecole des Mines de Paris, 06 - Sophia Antipolis (France)

1998-10-01

In this paper, experimental water and thermal balances with three proton exchange membrane fuel cells (PEMFC) are proposed. On the test facility of Ecole des Mines de Paris, three De Nora SPA fuel cell stacks have been successfully studied: An 1 kW{sub e} prototype using Nafion {sup trademark} 117, a 5 and 10 kW{sub e} module using Nafion {sup trademark} 115. The averaged water symmetry factor determines strategies to avoid drying membrane. So, we propose analytical solutions to find compromises between humidification and cooling conditions, which determines outlet temperatures of gases. For transport applications, the space occupied by the power module must be reduced. One of the main efforts consists in decreasing the operative pressure. Thus, if adequate cooling power is applied, we show experimentally and theoretically the possibility to use De Nora PEM fuel cells with low pressure, without specific external humidification. (orig.)

Northern Winter Climate Change: Assessment of Uncertainty in CMIP5 Projections Related to Stratosphere-Troposphere Coupling

Science.gov (United States)

Manzini, E.; Karpechko, A.Yu.; Anstey, J.; Shindell, Drew Todd; Baldwin, M.P.; Black, R.X.; Cagnazzo, C.; Calvo, N.; Charlton-Perez, A.; Christiansen, B.;

Observing Tropospheric Ozone From Space

Science.gov (United States)

Fishman, Jack

2000-01-01

The importance of tropospheric ozone embraces a spectrum of relevant scientific issues ranging from local environmental concerns, such as damage to the biosphere and human health, to those that impact global change questions, Such is climate warming. From an observational perspective, the challenge is to determine the tropospheric ozone global distribution. Because its lifetime is short compared with other important greenhouse gases that have been monitored over the past several decades, the distribution of tropospheric ozone cannot be inferred from a relatively small set of monitoring stations. Therefore, the best way to obtain a true global picture is from the use of space-based instrumentation where important spatial gradients over vast ocean expanses and other uninhabited areas can be properly characterized. In this paper, the development of the capability to measure tropospheric ozone from space over the past 15 years is summarized. Research in the late 1980s successfully led to the determination of the climatology of tropospheric ozone as a function of season; more recently, the methodology has improved to the extent where regional air pollution episodes can be characterized. The most recent modifications now provide quasi-global (50 N) to 50 S) maps on a daily basis. Such a data set would allow for the study of long-range (intercontinental) transport of air pollution and the quantification of how regional emissions feed into the global tropospheric ozone budget. Future measurement capabilities within this decade promise to offer the ability to provide Concurrent maps of the precursors to the in situ formation of tropospheric ozone from which the scientific community will gain unprecedented insight into the processes that control global tropospheric chemistry

Spatial variability of the structure of the lower troposphere over north western Indian Ocean during 1983 summer monsoon

Digital Repository Service at National Institute of Oceanography (India)

RameshKumar, M.R.; Sadhuram, Y.; Michael, G.S.; Rao, L.V.G.

The spatial variability of the structure of the lower troposphere over the north western Indian Ocean during the period 12th July to 2nd September, 1983 has been studied using the upper air data collected during the first scientific cruise of @i...

Changes to Saturn's zonal-mean tropospheric thermal structure after the 2010-2011 northern hemisphere storm

Energy Technology Data Exchange (ETDEWEB)

Achterberg, R. K.; Hesman, B. E. [Department of Astronomy, University of Maryland, College Park, MD 20742 (United States); Gierasch, P. J.; Conrath, B. J. [Department of Astronomy, Cornell University, Ithaca, NY 14853 (United States); Fletcher, L. N. [Atmospheric Oceanic and Planetary Physics, University of Oxford, Clarenden Laboratory, Parks Road, Oxford OX1 3PU (United Kingdom); Bjoraker, G. L.; Flasar, F. M., E-mail: Richard.K.Achterberg@nasa.gov [Planetary Systems Laboratory NASA/GSFC, Greenbelt, MD 20771 (United States)

2014-05-10

We use far-infrared (20-200 μm) data from the Composite Infrared Spectrometer on the Cassini spacecraft to determine the zonal-mean temperature and hydrogen para-fraction in Saturn's upper troposphere from observations taken before and after the large northern hemisphere storm in 2010-2011. During the storm, zonal mean temperatures in the latitude band between approximately 25°N and 45°N (planetographic latitude) increased by about 3 K, while the zonal mean hydrogen para-fraction decreased by about 0.04 over the same latitudes, at pressures greater than about 300 mbar. These changes occurred over the same latitude range as the disturbed cloud band seen in visible images. The observations are consistent with low para-fraction gas being brought up from the level of the water cloud by the strong convective plume associated with the storm, while being heated by condensation of water vapor, and then advected zonally by the winds near the plume tops in the upper troposphere.

Impact of land convection on troposphere-stratosphere exchange in the tropics

Directory of Open Access Journals (Sweden)

P. Ricaud

2007-11-01

Full Text Available The mechanism of troposphere-stratosphere exchange in the tropics was investigated from space-borne observations of the horizontal distributions of tropospheric-origin long-lived species, nitrous oxide (N₂O, methane (CH₄ and carbon monoxide (CO, from 150 to 70 hPa in March-April-May by the ODIN/Sub-Millimeter Radiometer (SMR, the Upper Atmosphere Research Satellite (UARS/Halogen Occultation Experiment (HALOE and the TERRA/Measurements Of Pollution In The Troposphere (MOPITT instruments in 2002–2004, completed by recent observations of the AURA/Microwave Limb Sounder (MLS instrument during the same season in 2005. The vertical resolution of the satellite measurements ranges from 2 to 4 km. The analysis has been performed on isentropic surfaces: 400 K (lower stratosphere for all the species and 360 K (upper troposphere only for CO. At 400 K (and 360 K for CO, all gases show significant longitudinal variations with peak-to-trough values of ~5–11 ppbv for N₂O, 0.07–0.13 ppmv for CH₄, and ~10 ppbv for CO (~40 ppbv at 360 K. The maximum amounts are primarily located over Africa and, depending on the species, secondary more or less pronounced maxima are reported above northern South America and South-East Asia. The lower stratosphere over the Western Pacific deep convective region where the outgoing longwave radiation is the lowest, the tropopause the highest and the coldest, appears as a region of minimum concentration of tropospheric trace species. The possible impact on trace gas concentration at the tropopause of the inhomogeneous distribution and intensity of the sources, mostly continental, of the horizontal and vertical transports in the troposphere, and of cross-tropopause transport was explored with the MOCAGE Chemistry Transport Model. In the simulations, significant longitudinal variations were found on the medium-lived CO (2-month lifetime with peak-to-trough value of ~20 ppbv at 360 K and

Heat loss during carbon dioxide insufflation: comparison of a nebulization based humidification device with a humidification and heating system.

Science.gov (United States)

Noll, Eric; Schaeffer, Roland; Joshi, Girish; Diemunsch, Sophie; Koessler, Stefanie; Diemunsch, Pierre

2012-12-01

This study compared the heat loss observed with the use of MR860 AEA Humidifier™ system (Fisher & Paykel Healthcare, New Zealand), which humidifies and heats the insufflated CO(2), and the use of the AeronebPro™ device (Aerogen, Ireland), which humidifies but does not heat the insufflated CO(2). With institutional approval, 16 experiments were conducted in 4 pigs. Each animal, acting as its own control, was studied at 8-day intervals in randomized sequence with the following four conditions: (1) control (C) no pneumoperitoneum; (2) standard (S) insufflation with nonhumidified, nonheated CO(2); (3) Aeroneb™ (A): insufflation with humidified, nonheated CO(2); and (4) MR860 AEA humidifier™ (MR): insufflation with humidified and heated CO(2). The measured heat loss after 720L CO(2) insufflation during the 4 h was 1.03 ± 0.75 °C (mean ± SEM) in group C; 3.63 ± 0.31 °C in group S; 3.03 ± 0.39 °C in group A; and 1.98 ± 0.09 °C in group MR. The ANOVA showed a significant difference with time (p = 0.0001) and with the insufflation technique (p = 0.024). Heat loss in group C was less than in group S after 60 min (p = 0.03), less than in group A after 70 min (p = 0.03), and less than in group MR after 150 min (p = 0.03). The heat loss in group MR was less than in group S after 50 min (p = 0.04) and less than in group A after 70 min (p = 0.02). After 160 min, the heat loss in group S was greater than in group A (p = 0.03). As far as heat loss is concerned, for laparoscopic procedures of less than 60 min, there is no benefit of using any humidification with or without heating. However, for procedures greater than 60 min, use of heating along with humidification, is superior.

Clinical factors affecting inspired gas humidification and oral dryness during noninvasive ventilation.

Science.gov (United States)

Oto, Jun; Imanaka, Hideaki; Nishimura, Masaji

2011-10-01

Oral dryness is a common complication during noninvasive ventilation (NIV). We measured the oral dryness of patients and performed a bench study to investigate factors related to humidification during NIV. Patients were randomly assigned into 2 groups: medium (Med group) and maximum (Max group) heated humidifier (HH) settings. Oral moistness was measured using an oral moisture-checking device, and the feeling of oral dryness was evaluated using a 0 to 10 numerical rating scale (NRS) at 0, 12, and 24 hours from the beginning of NIV and at 12 and 24 hours after NIV was discontinued. A bench study was performed to assess the effects of positive end-expiratory pressure (PEEP), the fraction of inspired oxygen (F(I)O(2)), and air leaks on absolute humidity. We evaluated 3 HH settings: no HH, HH at the medium setting, and HH at the maximum setting. The temperature in the outlet chamber was 31°C to 32°C for the medium HH setting and 38°C to 41°C for the maximum HH setting. In the clinical study, 12 patients were assigned to the Med group and 11 to the Max group. In the Med group, oral moistness decreased and NRS increased at 12 and 24 hours compared with 0 hours (P humidification and oral dryness during NIV. Copyright © 2011 Elsevier Inc. All rights reserved.

Humidification-Dehumidification (HDH) Spray Column Direct Contact Condenser Part I: Countercurrent Flow

International Nuclear Information System (INIS)

Karameldin, A.; Shouman, L.; Fadel, D.

2016-01-01

Humidification-De humidification (HDH) is a low grade energy desalination technology. Hot humid air and cooling spray water in counter current flow with direct contact is theoretically analyzed in the present work. Direct contact spray condenser is studied to obtain the effect of various parameters on its performance. A computer program describing the theoretical model is designed to solve one-dimensional differential equations by using Rung-Kutta method. The results show that the column length has a great effect on the performance of the spray condenser. At a column height of 2, 5,10, and 20 m the humidity of the outlet air decreases by 72, 89, 97, and 99% respectively. The humid air temperature has a great influence on the productivity; me an while the temperature difference between the humid air and sprayed water has less effect. A case study of a contiguous co-generation electricity and water in Nuclear Power Plants (NPP) shows that the optimal productivity by HDH is feasible and can reach more than 15 m"3 /day.m"2, enabling a total productivity that varied from 120,000 to 300,000 m"3 /day. The design curves describing the process are obtained together in addition to a formula for the optimal productivity in terms of humid air and sprayed water fluxes at different humid air temperatures is derived

Size distribution of salbutamol/ipratropium aerosols produced by different nebulizers in the absence and presence of heat and humidification.

Science.gov (United States)

Yang, Ssu-Han; Yang, Tsung-Ming; Lin, Hui-Ling; Tsai, Ying-Huang; Fang, Tien-Pei; Wan, Gwo-Hwa

2018-02-01

Few studies have evaluated the size distribution of inhaled and exhaled aerosolized drugs, or the effect of heated humidification on particle size and lung deposition. The present study evaluated these aspects of bronchodilator (salbutamol/ipratropium) delivery using a lung model in the absence and presence of heat and humidification. We positioned filters to collect and measure the initial drug, inhaled drug, and exhaled drug. Particle size distribution was evaluated using an 8-stage Marple personal cascade impactor with 0.2-μm polycarbonate filters. A greater inhaled drug mass was delivered using a vibrating mesh nebulizer (VMN) than by using a small volume nebulizer (SVN), when heated humidifiers were not employed. When heated and humidified medical gas was used, there was no significant difference between the inhaled drug mass delivered by the VMN and that delivered by the SVN. A significantly greater mass of inhaled 1.55-μm drug particles was produced by the VMN than with the SVN, under heated and humidified conditions. However, the mass median aerodynamic diameters (MMADs) of the aerosolized drug produced by the SVN and VMN did not differ significantly under the same conditions. The VMN produced more fine particles of salbutamol/ipratropium, and the drug particle size clearly increased in the presence of heat and humidification. Copyright © 2017 Elsevier Ltd. All rights reserved.

Warming and humidification of insufflation carbon dioxide in laparoscopic colonic surgery: a double-blinded randomized controlled trial.

Science.gov (United States)

Sammour, Tarik; Kahokehr, Arman; Hayes, Julian; Hulme-Moir, Mike; Hill, Andrew G

2010-06-01

We aimed to test the hypothesis that warming and humidification of insufflation CO2 would lead to reduced postoperative pain and improved recovery by reducing peritoneal inflammation in laparoscopic colonic surgery. Warming and humidification of insufflation gas is thought be beneficial in laparoscopic surgery, but evidence in prolonged laparoscopic procedures is lacking. We used a multicenter, double-blinded, randomized controlled design. The Study Group received warmed (37 degrees C), humidified (98% RH) insufflation carbon dioxide, and the Control Group received standard gas (19 degrees C, 0% RH). Anesthesia and analgesia were standardized. Intraoperative oesophageal temperature was measured at 15 minutes intervals. At the conclusion of surgery, the primary surgeon was asked to rate camera fogging on a Likert scale. Postoperative opiate usage was determined using Morphine Equivalent Daily Dose (MEDD), and pain was measured using visual analogue scores. Peritoneal and plasma cytokine concentrations were measured at 20 hours postoperatively. Postoperative recovery was measured using defined discharge and complication criteria, and the Surgical Recovery Score. Eighty-two patients were randomized, with 41 in each arm. Groups were well matched at baseline. Intraoperative core temperature was similar in both groups. Median camera fogging score was significantly worse in the Study group (4 vs. 2, P = 0.040). There were marginal differences in pain scores, but no significant differences were detected in MEDD usage, cytokine concentrations, or any recovery parameters measured. Warming and humidification of insufflation CO2 does not attenuate the early inflammatory cytokine response, and confers no clinically significant benefit in laparoscopic colonic surgery.

Variations of tropospheric methane over Japan during 1988–2010

Directory of Open Access Journals (Sweden)

Taku Umezawa

2014-05-01

Full Text Available We present observations of CH4 concentrations from the lower to upper troposphere (LT and UT over Japan during 1988–2010 based on aircraft measurements from the Tohoku University (TU. The analysis is aided by simulation results using an atmospheric chemistry transport model (i.e. ACTM. Tropospheric CH4 over Japan shows interannual and seasonal variations that are dependent on altitudes, primarily reflecting differences in air mass origins at different altitudes. The long-term trend and interannual variation of CH4 in the LT are consistent with previous reports of measurements at surface baseline stations in the northern hemisphere. However, those in the UT show slightly different features from those in the LT. In the UT, CH4 concentrations show a seasonal maximum in August due to efficient transport of air masses influenced by continental CH4 sources, while LT CH4 reaches its seasonal minimum during summer due to enhanced chemical loss. Vertical profiles of the CH4 concentrations also vary with season, reflecting the seasonal cycles at the respective altitudes. In summer, transport of CH4-rich air from Asian regions elevates UT CH4 levels, forming a uniform vertical profile above the mid-troposphere. On the other hand, CH4 decreases nearly monotonically with altitude in winter–spring. The ACTM simulations with different emission scenarios reproduce general features of the tropospheric CH4 variations over Japan. Tagged tracer simulations using the ACTM indicate substantial contributions of CH4 sources in South Asia and East Asia to the summertime high CH4 values observed in the UT. This suggests that our observations over Japan are highly sensitive to CH4 emission signals particularly from Asia.

Interpretation of TOMS Observations of Tropical Tropospheric Ozone with a Global Model and In Situ Observations

Science.gov (United States)

Martin, Randall V.; Jacob, Daniel J.; Logan, Jennifer A.; Bey, Isabelle; Yantosca, Robert M.; Staudt, Amanda C.; Fiore, Arlene M.; Duncan, Bryan N.; Liu, Hongyu; Ginoux, Paul

2004-01-01

We interpret the distribution of tropical tropospheric ozone columns (TTOCs) from the Total Ozone Mapping Spectrometer (TOMS) by using a global three-dimensional model of tropospheric chemistry (GEOS-CHEM) and additional information from in situ observations. The GEOS-CHEM TTOCs capture 44% of the variance of monthly mean TOMS TTOCs from the convective cloud differential method (CCD) with no global bias. Major discrepancies are found over northern Africa and south Asia where the TOMS TTOCs do not capture the seasonal enhancements from biomass burning found in the model and in aircraft observations. A characteristic feature of these northern topical enhancements, in contrast to southern tropical enhancements, is that they are driven by the lower troposphere where the sensitivity of TOMS is poor due to Rayleigh scattering. We develop an efficiency correction to the TOMS retrieval algorithm that accounts for the variability of ozone in the lower troposphere. This efficiency correction increases TTOC's over biomass burning regions by 3-5 Dobson units (DU) and decreases them by 2-5 DU over oceanic regions, improving the agreement between CCD TTOCs and in situ observations. Applying the correction to CCD TTOCs reduces by approximately DU the magnitude of the "tropical Atlantic paradox" [Thompson et al, 2000], i.e. the presence of a TTOC enhancement over the southern tropical Atlantic during the northern African biomass burning season in December-February. We reproduce the remainder of the paradox in the model and explain it by the combination of upper tropospheric ozone production from lightning NOx, peristent subsidence over the southern tropical Atlantic as part of the Walker circulation, and cross-equatorial transport of upper tropospheric ozone from northern midlatitudes in the African "westerly duct." These processes in the model can also account for the observed 13-17 DU persistent wave-1 pattern in TTOCs with a maximum above the tropical Atlantic and a minimum

The protective effect of different airway humidification liquids to lung after tracheotomy in traumatic brain injury: The role of pulmonary surfactant protein-A (SP-A).

Science.gov (United States)

Su, Xinyang; Li, Zefu; Wang, Meilin; Li, Zhenzhu; Wang, Qingbo; Lu, Wenxian; Li, Xiaoli; Zhou, Youfei; Xu, Hongmei

2016-02-10

The purpose of this study was to establish a rat model of a brain injury with tracheotomy and compared the wetting effects of different airway humidification liquids, afterward, the best airway humidification liquid was selected for the clinical trial, thus providing a theoretical basis for selecting a proper airway humidification liquid in a clinical setting. Rats were divided into a sham group, group A (0.9% NaCl), group B (0.45% NaCl), group C (0.9% NaCl+ambroxol) and group D (0.9% NaCl+Pulmicort). An established rat model of traumatic brain injury with tracheotomy was used. Brain tissue samples were taken to determine water content, while lung tissue samples were taken to determine wet/dry weight ratio (W/D), histological changes and expression levels of SP-A mRNA and SP-A protein. 30 patients with brain injury and tracheotomy were selected and divided into two groups based on the airway humidification liquid instilled in the trachea tube, 0.45% NaCl and 0.9% NaCl+ambroxol. Blood was then extracted from the patients to measure the levels of SP-A, interleukin-6 (IL-6), interleukin-8 (IL-8) and tumour necrosis factor-α (TNF-α). The difference between group C and other groups in lung W/D and expression levels of SP-A mRNA and SP-A protein was significant (Phumidification liquid. Copyright © 2015 Elsevier B.V. All rights reserved.

Ground-based remote sensing of tropospheric water vapour isotopologues within the project MUSICA

Directory of Open Access Journals (Sweden)

M. Schneider

2012-12-01

Full Text Available Within the project MUSICA (MUlti-platform remote Sensing of Isotopologues for investigating the Cycle of Atmospheric water, long-term tropospheric water vapour isotopologue data records are provided for ten globally distributed ground-based mid-infrared remote sensing stations of the NDACC (Network for the Detection of Atmospheric Composition Change. We present a new method allowing for an extensive and straightforward characterisation of the complex nature of such isotopologue remote sensing datasets. We demonstrate that the MUSICA humidity profiles are representative for most of the troposphere with a vertical resolution ranging from about 2 km (in the lower troposphere to 8 km (in the upper troposphere and with an estimated precision of better than 10%. We find that the sensitivity with respect to the isotopologue composition is limited to the lower and middle troposphere, whereby we estimate a precision of about 30‰ for the ratio between the two isotopologues HD¹⁶O and H₂¹⁶O. The measurement noise, the applied atmospheric temperature profiles, the uncertainty in the spectral baseline, and the cross-dependence on humidity are the leading error sources. We introduce an a posteriori correction method of the cross-dependence on humidity, and we recommend applying it to isotopologue ratio remote sensing datasets in general. In addition, we present mid-infrared CO₂ retrievals and use them for demonstrating the MUSICA network-wide data consistency. In order to indicate the potential of long-term isotopologue remote sensing data if provided with a well-documented quality, we present a climatology and compare it to simulations of an isotope incorporated AGCM (Atmospheric General Circulation Model. We identify differences in the multi-year mean and seasonal cycles that significantly exceed the estimated errors, thereby indicating deficits in the modeled atmospheric water cycle.

Ground-based remote sensing of tropospheric water vapour isotopologues within the project MUSICA

Science.gov (United States)

Schneider, M.; Barthlott, S.; Hase, F.; González, Y.; Yoshimura, K.; García, O. E.; Sepúlveda, E.; Gomez-Pelaez, A.; Gisi, M.; Kohlhepp, R.; Dohe, S.; Blumenstock, T.; Wiegele, A.; Christner, E.; Strong, K.; Weaver, D.; Palm, M.; Deutscher, N. M.; Warneke, T.; Notholt, J.; Lejeune, B.; Demoulin, P.; Jones, N.; Griffith, D. W. T.; Smale, D.; Robinson, J.

2012-12-01

Within the project MUSICA (MUlti-platform remote Sensing of Isotopologues for investigating the Cycle of Atmospheric water), long-term tropospheric water vapour isotopologue data records are provided for ten globally distributed ground-based mid-infrared remote sensing stations of the NDACC (Network for the Detection of Atmospheric Composition Change). We present a new method allowing for an extensive and straightforward characterisation of the complex nature of such isotopologue remote sensing datasets. We demonstrate that the MUSICA humidity profiles are representative for most of the troposphere with a vertical resolution ranging from about 2 km (in the lower troposphere) to 8 km (in the upper troposphere) and with an estimated precision of better than 10%. We find that the sensitivity with respect to the isotopologue composition is limited to the lower and middle troposphere, whereby we estimate a precision of about 30‰ for the ratio between the two isotopologues HD16O and H216O. The measurement noise, the applied atmospheric temperature profiles, the uncertainty in the spectral baseline, and the cross-dependence on humidity are the leading error sources. We introduce an a posteriori correction method of the cross-dependence on humidity, and we recommend applying it to isotopologue ratio remote sensing datasets in general. In addition, we present mid-infrared CO2 retrievals and use them for demonstrating the MUSICA network-wide data consistency. In order to indicate the potential of long-term isotopologue remote sensing data if provided with a well-documented quality, we present a climatology and compare it to simulations of an isotope incorporated AGCM (Atmospheric General Circulation Model). We identify differences in the multi-year mean and seasonal cycles that significantly exceed the estimated errors, thereby indicating deficits in the modeled atmospheric water cycle.

Is tropospheric weather influenced by solar wind through atmospheric vertical coupling downward control?

Science.gov (United States)

Prikryl, Paul; Tsukijihara, Takumi; Iwao, Koki; Muldrew, Donald B.; Bruntz, Robert; Rušin, Vojto; Rybanský, Milan; Turňa, Maroš; Šťastný, Pavel; Pastirčák, Vladimír

2017-04-01

More than four decades have passed since a link between solar wind magnetic sector boundary structure and mid-latitude upper tropospheric vorticity was discovered (Wilcox et al., Science, 180, 185-186, 1973). The link has been later confirmed and various physical mechanisms proposed but apart from controversy, little attention has been drawn to these results. To further emphasize their importance we investigate the occurrence of mid-latitude severe weather in the context of solar wind coupling to the magnetosphere-ionosphere-atmosphere (MIA) system. It is observed that significant snowstorms, windstorms and heavy rain, particularly if caused by low pressure systems in winter, tend to follow arrivals of high-speed solar wind. Previously published statistical evidence that explosive extratropical cyclones in the northern hemisphere tend to occur after arrivals of high-speed solar wind streams from coronal holes (Prikryl et al., Ann. Geophys., 27, 1-30, 2009; Prikryl et al., J. Atmos. Sol.-Terr. Phys., 149, 219-231, 2016) is corroborated for the southern hemisphere. A physical mechanism to explain these observations is proposed. The leading edge of high-speed solar wind streams is a locus of large-amplitude magneto-hydrodynamic waves that modulate Joule heating and/or Lorentz forcing of the high-latitude lower thermosphere generating medium-scale atmospheric gravity waves that propagate upward and downward through the atmosphere. Simulations of gravity wave propagation in a model atmosphere using the Transfer Function Model (Mayr et al., Space Sci. Rev., 54, 297-375, 1990) show that propagating waves originating in the thermosphere can excite a spectrum of gravity waves in the lower atmosphere. In spite of significantly reduced amplitudes but subject to amplification upon reflection in the upper troposphere, these gravity waves can provide a lift of unstable air to release instabilities in the troposphere thus initiating convection to form cloud/precipitation bands

Energy, exergy, economic and environmental (4E) analysis of a solar desalination system with humidification-dehumidification

International Nuclear Information System (INIS)

Deniz, Emrah; Çınar, Serkan

2016-01-01

Highlights: • Possibility of suppling all energy consumption from solar energy was tested. • Air and water-heated humidification-dehumidification desalination system was proposed. • Energy, exergy, economic and environmental analysis were performed. • Productivity and performance of the desalination system was analyzed. • Various operational parameters were investigated. - Abstract: A novel humidification-dehumidification (HDH) solar desalination system is designed and tested with actual conditions and solar energy was used to provide both thermal and electrical energy. Energy-exergy analyses of the system are made and economic and enviro-economic properties are investigated using data obtained from experimental studies. In this way, economic and environmental impacts of the HDH solar desalination systems have also been determined. The maximum daily energy efficiency of the system was calculated as 31.54% and the maximum exergy efficiency was found as 1.87%. The maximum fresh water production rate is obtained as 1117.3 g/h. The estimated cost of fresh water produced through the designed HDH system is 0.0981 USD/L and enviro-economic parameter is 2.4041 USD/annum.

Observed OH and HO2 concentrations in the upper troposphere inside and outside of Asian monsoon influenced air.

Science.gov (United States)

Marno, D. R.; Künstler, C.; Hens, K.; Tatum Ernest, C.; Broch, S.; Fuchs, H.; Martinez, M.; Bourtsoukidis, E.; Williams, J.; Holland, F.; Hofzumahaus, A.; Tomsche, L.; Fischer, H.; Klausner, T.; Schlager, H.; Eirenschmalz, L.; Stratmann, G.; Stock, P.; Ziereis, H.; Roiger, A.; Bohn, B.; Zahn, A.; Wahner, A.; Lelieveld, J.; Harder, H.

2016-12-01

The Asian monsoon convectively transports pollutants like volatile organic compounds (VOCs), NOx, and SO2 from the boundary layer over South Asia into the upper troposphere where they can potentially enter the stratosphere, or be dispersed globally. Therefore, it is crucial to understand the oxidizing capacity of this system regarding the rate of aerosol formation, and conversion of pollutants into compounds that have much shorter atmospheric lifetimes. OH plays a central role in this oxidation process. During the OMO-ASIA campaign in the summer of 2015, OH and HO2 were measured onboard the High Altitude Long-Range (HALO) Research Aircraft. Two laser-induced fluorescence instruments based on the fluorescence assay by gas expansion technique (LIF-FAGE) had been deployed, the AIR-LIF instrument from Forschungszentrum Jülich GmbH and the HORUS instrument from the Max Planck Institute for Chemistry, Mainz. To measure the chemical background of OH potentially produced inside the HORUS instrument from highly oxidized VOCs, atmospheric OH is scavenged by an Inlet Pre-injector (IPI) system. This was the first time an IPI system was implemented within an airborne LIF-FAGE instrument measuring OH and HO2. Throughout this campaign OH and HO2 were measured at 12 to 15km within the Asian monsoon anticyclone. These measurements have been contrasted by probing air outside the anticyclone in air masses influenced by North American emissions, and in very clean air masses originated from the southern hemisphere.

Innovation, systemic appropriation and prevention in the granite mining sector: The case of humidification.

Science.gov (United States)

Mendes, R W B; Pueyo, V; Béguin, P; Duarte, F J C M

2017-01-01

This research was conducted in the Brazilian granite mining sector. After epidemiological studies, it was established that professional pneumoconiosis is related to the inhalation of dust. Therefore, the Brazilian mining health and safety regulatory standard made it compulsory to provide humidification throughout the extraction and mineral treatment processes. To develop the concept of systemic appropriation of the technological innovations that aim to protect the worker's health. Until now, appropriation has usually been presented in its individual dimensions. In this article, the focus is placed on the collective and organizational aspects of this appropriation. Two methodological approaches were used: interviews with the different individuals involved in order to report the history of the implementation of technical devices which meet the humidification norm; and ergonomic analysis of the work of the operators who used these devices. The appropriation of the technical devices occurred at two distinct levels: 1) Individual, related to the direct contact of the operator with the instrument; 2) Systemic, as the effects of the innovation propagated through the system affecting interdependent tasks, adaptation of the work organization and new production strategies. The implementation of prevention norms require innovations which are necessarily accompanied by transformations in the companies' techniques, work and management.

Tropospheric Ozone Climatology over Irene, South Africa, From 1990-1994 and 1998-2002

Science.gov (United States)

Diab, R. D.; Thompson, A. M.; Marl, K.; Ramsay, L.; Coetzee, G. J. R.

2004-01-01

This paper describes ozone profiles from sonde data during the period of NASA s TRACE-A and the more recent SHADOZ (Southern Hemisphere Additional Ozonesondes) period. The data were taken by the South African Weather Service at the Irene (25 deg.54 min S; 28 deg. 13 min. E) station near Pretoria, South Africa, an area that is a unique mixture of local industry, heavy biofuels use and importation of biomass burning ozone from neighboring countries to the north. The main findings are: (1) With its geographical position at the edge of the subtropical transition zone, mid- latitude dynamical influences are evident at Irene, predominantly in winter when upper tropospheric ozone is enhanced as a result of stratospheric-tropospheric exchange. (2) There has been an increase in the near-surface ozone amount between the early 1990s and a decade later, presumably due to an influx of rural population toward the Johannesburg-Pretoria area, as well as with industrial growth and development. (3) Most significant for developing approaches for satellite ozone profile climatologies, cluster analysis has enabled the delineation of a background and "most polluted" profile. Enhancements of at least 30% occur throughout the troposphere in spring and in certain layers increases of 100 % are observed.

Tropospheric Ozone from the TOMS TDOT (TOMS-Direct-Ozone-in-Troposphere) Technique During SAFARI-2000

Science.gov (United States)

Stone, J. B.; Thompson, A. M.; Frolov, A. D.; Hudson, R. D.; Bhartia, P. K. (Technical Monitor)

2002-01-01

There are a number of published residual-type methods for deriving tropospheric ozone from TOMS (Total Ozone Mapping Spectrometer). The basic concept of these methods is that within a zone of constant stratospheric ozone, the tropospheric ozone column can be computed by subtracting stratospheric ozone from the TOMS Level 2 total ozone column, We used the modified-residual method for retrieving tropospheric ozone during SAFARI-2000 and found disagreements with in-situ ozone data over Africa in September 2000. Using the newly developed TDOT (TOMS-Direct-Ozone-in-Troposphere) method that uses TOMS radiances and a modified lookup table based on actual profiles during high ozone pollution periods, new maps were prepared and found to compare better to soundings over Lusaka, Zambia (15.5 S, 28 E), Nairobi and several African cities where MOZAIC aircraft operated in September 2000. The TDOT technique and comparisons are described in detail.

Kinetics programs for simulation of tropospheric photochemistry on the global scale

International Nuclear Information System (INIS)

Elliott, S.; Kao, C.Y.J.; Turco, R.P.; Zhao, X.P.

1993-08-01

The study of tropospheric kinetics underlies global change because key greenhouse gases are photochemically active. Modeling of tropospheric chemistry on a global scale is essential because some indirect greenhouse gases are short-lived and interact in a non-linear fashion. It is also extremely challenging, however; the global change grid is extensive in both the physical and temporal domains, and critical lower atmospheric species include the organics and their oxidized derivatives, which are numerous. Several types of optimization may be incorporated into kinetics modules to enhance their ability to simulate the complete lower atmospheric gas phase chemical system. (1) The photochemical integrator can be accelerated by avoiding matrix and iterative solutions and by establishing families. Accuracy and mass conservation are sacrificed in the absence of iteration, but atom balancing is restorable post hoc. (2) Chemistry can be arranged upon the massive grid to exploit parallel processing, and solutions to its continuity equations can be automated to permit experimentation with species and reaction lists or family definitions. Costs in programming effort will be incurred in these cases. (3) Complex hydrocarbon decay sequences can be streamlined either through structural lumping methods descended from smog investigations, which require considerable calibration, or by defining surrogates for classes of compounds, with a loss in constituent detail. From among the available options, the most advantageous permutations will vary with the specific nature of any eventual global scale study, and there is likely to be demand for many approaches. Tracer transport codes serve as a foundation upon which tropospheric chemistry packages will be tested. Encroachment of the NO x sphere of influence upon tropical rain forests and the upper free troposphere are two examples of specific problems to which full three-dimensional chemical simulations might be applied

Effects of anthropogenic emissions on tropospheric ozone and its radiative forcing

Energy Technology Data Exchange (ETDEWEB)

Berntsen, T.; Isaksen, I.S.A.; Fuglestvedt, J.S.; Myhre, G.; Larsen, T. Alsvik; Stordal, F.; Freckleton, R.S.; Shine, K.P.

1997-12-31

As described in this report, changes in tropospheric ozone since pre-industrial times due to changes in emissions have been calculated by the University of Oslo global three-dimensional photochemical model. The radiative forcing caused by the increase in ozone has been calculated by means of two independent radiative transfer models: the University of Reading model (Reading), and the University of Oslo/Norwegian Institute for Air Research model (OsloRad). Significant increases in upper tropospheric ozone concentrations are found at northern mid-latitudes at about 10 km altitude. In the tropical regions the largest increase is found at about 15 km altitude. The increase is found to be caused mainly by enhanced in situ production due to transport of precursors from the boundary layer, with a smaller contribution from increased transport of ozone produced in the boundary layer. The lifetime of ozone in the troposphere decreased by about 35% as a result of enhanced concentrations of HO{sub 2}. The calculated increase in surface ozone in Europe is in good agreement with observations. The calculations of radiative forcing include the effect of clouds and allow for thermal adjustment in the stratosphere. The global and annual averaged radiative forcing at the tropopause from both models are in the lower part of the Intergovernmental Panel on Climate Change estimated range. The calculated radiative forcing is similar in magnitude to the negative radiative forcing by sulfate aerosols, but displaced southward in source regions at northern mid-latitudes. The increase in tropospheric ozone is calculated to have cooled the lower stratosphere by up to 0.9 K, with possibly half of this cooling occurring in the past 2 to 3 decades. 76 refs., 16 figs., 9 tabs.

Complex chemical composition of colored surface films formed from reactions of propanal in sulfuric acid at upper troposphere/lower stratosphere aerosol acidities.

Science.gov (United States)

Van Wyngarden, A L; Pérez-Montaño, S; Bui, J V H; Li, E S W; Nelson, T E; Ha, K T; Leong, L; Iraci, L T

Particles in the upper troposphere and lower stratosphere (UT/LS) consist mostly of concentrated sulfuric acid (40-80 wt %) in water. However, airborne measurements have shown that these particles also contain a significant fraction of organic compounds of unknown chemical composition. Acid-catalyzed reactions of carbonyl species are believed to be responsible for significant transfer of gas phase organic species into tropospheric aerosols and are potentially more important at the high acidities characteristic of UT/LS particles. In this study, experiments combining sulfuric acid (H 2 SO 4 ) with propanal and with mixtures of propanal with glyoxal and/or methylglyoxal at acidities typical of UT/LS aerosols produced highly colored surface films (and solutions) that may have implications for aerosol properties. In order to identify the chemical processes responsible for the formation of the surface films, attenuated total reflectance-Fourier transform infrared (ATR-FTIR) and 1 H nuclear magnetic resonance (NMR) spectroscopies were used to analyze the chemical composition of the films. Films formed from propanal were a complex mixture of aldol condensation products, acetals and propanal itself. The major aldol condensation products were the dimer (2-methyl-2-pentenal) and 1,3,5-trimethylbenzene that was formed by cyclization of the linear aldol condensation trimer. Additionally, the strong visible absorption of the films indicates that higher-order aldol condensation products must also be present as minor species. The major acetal species were 2,4,6-triethyl-1,3,5-trioxane and longer-chain linear polyacetals which are likely to separate from the aqueous phase. Films formed on mixtures of propanal with glyoxal and/or methylglyoxal also showed evidence of products of cross-reactions. Since cross-reactions would be more likely than self-reactions under atmospheric conditions, similar reactions of aldehydes like propanal with common aerosol organic species like glyoxal

Tropospheric NO2 over China

NARCIS (Netherlands)

A, van der R.J.; Peters, D.H.M.U.; Kuenen, J.J.P.; Eskes, H.J.; Boersma, K.F.; Roozendael, Van M.; Smedt, de I.; Zhang, P.; Kelder, H.M.; Lacoste, H.; Ouwehand, L.

2006-01-01

The results are presented of a study to tropospheric NO2 over China, based on measurements from the satellite instruments GOME and SCIAMACHY. A data set of 10 year tropospheric NO2 has been processed from GOME and SCIAMACHY observations using a combined retrieval/assimilation approach. This approach

Stratospheric ozone intrusion events and their impacts on tropospheric ozone in the Southern Hemisphere

Directory of Open Access Journals (Sweden)

J. W. Greenslade

2017-09-01

Full Text Available Stratosphere-to-troposphere transport (STT provides an important natural source of ozone to the upper troposphere, but the characteristics of STT events in the Southern Hemisphere extratropics and their contribution to the regional tropospheric ozone budget remain poorly constrained. Here, we develop a quantitative method to identify STT events from ozonesonde profiles. Using this method we estimate the seasonality of STT events and quantify the ozone transported across the tropopause over Davis (69° S, 2006–2013, Macquarie Island (54° S, 2004–2013, and Melbourne (38° S, 2004–2013. STT seasonality is determined by two distinct methods: a Fourier bandpass filter of the vertical ozone profile and an analysis of the Brunt–Väisälä frequency. Using a bandpass filter on 7–9 years of ozone profiles from each site provides clear detection of STT events, with maximum occurrences during summer and minimum during winter for all three sites. The majority of tropospheric ozone enhancements owing to STT events occur within 2.5 and 3 km of the tropopause at Davis and Macquarie Island respectively. Events are more spread out at Melbourne, occurring frequently up to 6 km from the tropopause. The mean fraction of total tropospheric ozone attributed to STT during STT events is  ∼ 1. 0–3. 5 % at each site; however, during individual events, over 10 % of tropospheric ozone may be directly transported from the stratosphere. The cause of STTs is determined to be largely due to synoptic low-pressure frontal systems, determined using coincident ERA-Interim reanalysis meteorological data. Ozone enhancements can also be caused by biomass burning plumes transported from Africa and South America, which are apparent during austral winter and spring and are determined using satellite measurements of CO. To provide regional context for the ozonesonde observations, we use the GEOS-Chem chemical transport model, which is too coarsely

The Effect of Cirrus Clouds on Water Vapor Transport in the Upper Troposphere and Lower Stratosphere

Science.gov (United States)

Lei, L.; McCormick, M. P.; Anderson, J.

2017-12-01

Water vapor plays an important role in the Earth's radiation budget and stratospheric chemistry. It is widely accepted that a large percentage of water vapor entering the stratosphere travels through the tropical tropopause and is dehydrated by the cold tropopause temperature. The vertical transport of water vapor is also affected by the radiative effects of cirrus clouds in the tropical tropopause layer. This latter effect of cirrus clouds was investigated in this research. The work focuses on the tropical and mid-latitude region (50N-50S). Water vapor data from the Microwave Limb Sounder (MLS) and cirrus cloud data from the Cloud-Aerosol Lidar and Infrared pathfinder Satellite Observation (CALIPSO) instruments were used to investigate the relationship between the water vapor and the occurrence of cirrus cloud. A 10-degree in longitude by 10-degree in latitude resolution was chosen to bin the MLS and CALIPSO data. The result shows that the maximum water vapor in the upper troposphere (below 146 hPa) is matched very well with the highest frequency of cirrus cloud occurrences. Maximum water vapor in the lower stratosphere (100 hPa) is partly matched with the maximum cirrus cloud occurrence in the summer time. The National Oceanic and Atmospheric Administration Interpolated Outgoing Longwave Radiation data and NCEP-DOE Reanalysis 2 wind data were used also to investigate the relationship between the water vapor entering the stratosphere, deep convection, and wind. Results show that maximum water vapor at 100 hPa coincides with the northern hemisphere summer-time anticyclone. The effects from both single-layer cirrus clouds and cirrus clouds above the anvil top on the water vapor entering the stratosphere were also studied and will be presented.

Driving Roles of Tropospheric and Stratospheric Thermal Anomalies in Intensification and Persistence of the Arctic Superstorm in 2012

Science.gov (United States)

Tao, Wei; Zhang, Jing; Fu, Yunfei; Zhang, Xiangdong

2017-10-01

Intense synoptic-scale storms have been more frequently observed over the Arctic during recent years. Specifically, a superstorm hit the Arctic Ocean in August 2012 and preceded a new record low Arctic sea ice extent. In this study, the major physical processes responsible for the storm's intensification and persistence are explored through a series of numerical modeling experiments with the Weather Research and Forecasting model. It is found that thermal anomalies in troposphere as well as lower stratosphere jointly lead to the development of this superstorm. Thermal contrast between the unusually warm Siberia and the relatively cold Arctic Ocean results in strong troposphere baroclinicity and upper level jet, which contribute to the storm intensification initially. On the other hand, Tropopause Polar Vortex (TPV) associated with the thermal anomaly in lower stratosphere further intensifies the upper level jet and accordingly contributes to a drastic intensification of the storm. Stacking with the enhanced surface low, TPV intensifies further, which sustains the storm to linger over the Arctic Ocean for an extended period.

[Comparison of ability to humidification of inspired air through the nose and oral cavity using dew point hygrometer].

Science.gov (United States)

Paczesny, Daniel; Rapiejko, Piotr; Weremczuk, Jerzy; Jachowicz, Ryszard; Jurkiewicz, Dariusz

2007-01-01

Aim of this study was to check at the hospital the dew point hygrometer for fast measurement of air humidity in upper airways. The nose ability to humidification of inspired air and partially recover moisture from expired air was evaluated. Measurements from respiration through the nose and oral cavity were compared. The study was carried out in a group of 30 people (8 female and 22 male), age group 18 to 70 (mean age: 37 years old). In 22 of the participants there were no deviation from normal state in laryngologic examination, while in 4 participants nasal septum deviation without imaired nasal; oatency was found, in other 3--nasal vonchae hyperthrophy and in 1--nasal polips (grade I). The measurements of air humidity in upper air ways was done using specially designed and constructed measurement system. The air inspired through the nose and oral cavity is humidified. For typical external conditions (T = 22 degrees C i RH = 50%) the nose humidifies inspired air two times better then oral cavity (short time range of measurement approximately 1 min). Moisture from expired air through the nose is partially recovered (for patients with regular patency is 25% of the value of humidifying of inspired air). The oral cavity does not have ability to partially recovery moisture form expired air. The paper presented fast dew point hygrometer based on semiconductor microsystems for measurement humidity in inspired and expired air through the nose and oral cavity. Presented system can be a proper instrument for evaluation of nasal functions.

Exposure and acute exposure-effects before and after modification of a contaminated humidification system in a synthetic-fibre plant

NARCIS (Netherlands)

Pal, TM; de Monchy, JGR; Groothoff, JW; Post, D

Objective: Follow-up study of exposure and acute exposure-effects after modification to steam humidification of a contaminated cold water system which had caused an outbreak of humidifier fever in a synthetic-fibre plant. Methods: Before and after modification of the system aerobiological

Photochemistry and transport of tropospheric ozone and its precursors in urban and remote environments

Science.gov (United States)

Anderson, Daniel Craig

Tropospheric ozone (O3) adversely affects human health, reduces crop yields, and contributes to climate forcing. To limit these effects, the processes controlling O3 abundance as well as that of its precursor molecules must be fully characterized. Here, I examine three facets of O 3 production, both in heavily polluted and remote environments. First, using in situ observations from the DISCOVER-AQ field campaign in the Baltimore/Washington region, I evaluate the emissions of the O 3 precursors CO and NOx (NOx = NO + NO2) in the National Emissions Inventory (NEI). I find that CO/NOx emissions ratios derived from observations are 21% higher than those predicted by the NEI. Comparisons to output from the CMAQ model suggest that CO in the NEI is accurate within 15 +/- 11%, while NOx emissions are overestimated by 51-70%, likely due to errors in mobile sources. These results imply that ambient ozone concentrations will respond more efficiently to NOx controls than current models suggest. I then investigate the source of high O3 and low H2O structures in the Tropical Western Pacific (TWP). A combination of in situ observations, satellite data, and models show that the high O3 results from photochemical production in biomass burning plumes from fires in tropical Southeast Asia and Central Africa; the low relative humidity results from large-scale descent in the tropics. Because these structures have frequently been attributed to mid-latitude pollution, biomass burning in the tropics likely contributes more to the radiative forcing of climate than previously believed. Finally, I evaluate the processes controlling formaldehyde (HCHO) in the TWP. Convective transport of near surface HCHO leads to a 33% increase in upper tropospheric HCHO mixing ratios; convection also likely increases upper tropospheric CH 3OOH to ~230 pptv, enough to maintain background HCHO at ~75 pptv. The long-range transport of polluted air, with NO four times the convectively controlled background

Impact of uncertainties in inorganic chemical rate constants on tropospheric composition and ozone radiative forcing

Directory of Open Access Journals (Sweden)

B. Newsome

2017-12-01

regions such as the tropics, poles and upper troposphere are most uncertain. This chemical uncertainty is sufficiently large to suggest that rate constant uncertainty should be considered alongside other processes when model results disagree with measurement. Calculations for the pre-industrial simulation allow a tropospheric ozone radiative forcing to be calculated of 0.412 ± 0.062 W m−2. This uncertainty (13 % is comparable to the inter-model spread in ozone radiative forcing found in previous model–model intercomparison studies where the rate constants used in the models are all identical or very similar. Thus, the uncertainty of tropospheric ozone radiative forcing should expanded to include this additional source of uncertainty. These rate constant uncertainties are significant and suggest that refinement of supposedly well-known chemical rate constants should be considered alongside other improvements to enhance our understanding of atmospheric processes.

Seasonality of Peroxyacetyl nitrate (PAN in the upper troposphere and lower stratosphere using the MIPAS-E instrument

Directory of Open Access Journals (Sweden)

D. P. Moore

2010-07-01

Full Text Available The Michelson Interferometer for Passive Atmospheric Sounding onboard ENVISAT (MIPAS–E offers the opportunity to detect and spectrally resolve many atmospheric minor constituents affecting atmospheric chemistry. In this paper, we retrieve global, seasonal PAN volume mixing ratio (vmr data from MIPAS-E measurements made in January, March, August and October 2003 and present results from this scheme between approximately 300 and 150 hPa. The total error on a single PAN retrieval is better than 20% outside the tropics and better than 50% in the tropics where uncertainties in water vapor dominate the total error budget. We observe clear differences in the seasonal cycle of PAN in our data, linked closely to biomass burning regions and growing seasons. Highest Northern Hemisphere mid-latitude PAN vmrs were observed in August (300–600 pptv on average compared with the January and October data (less than 250 pptv on average. In the March 2003 data we observe highest PAN vmrs in the tropics with evidence of vmrs between 600 and 1000 pptv over Eastern Asia and over the Central Pacific at 333 hPa. The vertical distribution of PAN as a function of latitude (i.e. the zonal mean highlights the strong inter-annual variability of PAN in the upper troposphere and lower stratosphere (UTLS, most pronounced poleward of 40° N (up to 400 pptv over the year. The variability of PAN in the tropical UTLS is also significant and we derive a variability of up to 250 pptv in the averages between January and October 2003. These results represent the first seasonal observations of PAN in the UTLS.

Tropospheric radiowave propagation beyond the horizon

CERN Document Server

Du Castel, François

1966-01-01

Tropospheric Radiowave Propagation Beyond the Horizon deals with developments concerning the tropospheric propagation of ultra-short radio waves beyond the horizon, with emphasis on the relationship between the theoretical and the experimental. Topics covered include the general conditions of propagation in the troposphere; general characteristics of propagation beyond the horizon; and attenuation in propagation. This volume is comprised of six chapters and begins with a brief historical look at the various stages that have brought the technique of transhorizon links to its state of developmen

The effects of gas humidification with high-flow nasal cannula on cultured human airway epithelial cells.

Science.gov (United States)

Chidekel, Aaron; Zhu, Yan; Wang, Jordan; Mosko, John J; Rodriguez, Elena; Shaffer, Thomas H

2012-01-01

Humidification of inspired gas is important for patients receiving respiratory support. High-flow nasal cannula (HFNC) effectively provides temperature and humidity-controlled gas to the airway. We hypothesized that various levels of gas humidification would have differential effects on airway epithelial monolayers. Calu-3 monolayers were placed in environmental chambers at 37°C with relative humidity (RH) 90% (HFNC) for 4 and 8 hours with 10 L/min of room air. At 4 and 8 hours, cell viability and transepithelial resistance measurements were performed, apical surface fluid was collected and assayed for indices of cell inflammation and function, and cells were harvested for histology (n = 6/condition). Transepithelial resistance and cell viability decreased over time (P < 0.001) between HFNC and dry groups (P < 0.001). Total protein secretion increased at 8 hours in the dry group (P < 0.001). Secretion of interleukin (IL)-6 and IL-8 in the dry group was greater than the other groups at 8 hours (P < 0.001). Histological analysis showed increasing injury over time for the dry group. These data demonstrate that exposure to low humidity results in reduced epithelial cell function and increased inflammation.

The Effects of Gas Humidification with High-Flow Nasal Cannula on Cultured Human Airway Epithelial Cells

Directory of Open Access Journals (Sweden)

Aaron Chidekel

2012-01-01

Full Text Available Humidification of inspired gas is important for patients receiving respiratory support. High-flow nasal cannula (HFNC effectively provides temperature and humidity-controlled gas to the airway. We hypothesized that various levels of gas humidification would have differential effects on airway epithelial monolayers. Calu-3 monolayers were placed in environmental chambers at 37°C with relative humidity (RH 90% (HFNC for 4 and 8 hours with 10 L/min of room air. At 4 and 8 hours, cell viability and transepithelial resistance measurements were performed, apical surface fluid was collected and assayed for indices of cell inflammation and function, and cells were harvested for histology (n=6/condition. Transepithelial resistance and cell viability decreased over time (P<0.001 between HFNC and dry groups (P<0.001. Total protein secretion increased at 8 hours in the dry group (P<0.001. Secretion of interleukin (IL-6 and IL-8 in the dry group was greater than the other groups at 8 hours (P<0.001. Histological analysis showed increasing injury over time for the dry group. These data demonstrate that exposure to low humidity results in reduced epithelial cell function and increased inflammation.

Tropospheric ozone changes, radiative forcing and attribution to emissions in the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP

Directory of Open Access Journals (Sweden)

D. S. Stevenson

2013-03-01

: decreases in the tropical lower troposphere, associated with increases in water vapour; and increases in the sub-tropical to mid-latitude upper troposphere, associated with increases in lightning and stratosphere-to-troposphere transport. Climate change has relatively small impacts on global mean tropospheric ozone RF.

An Aircraft-Based Upper Troposphere Lower Stratosphere O3, CO, and H2O Climatology for the Northern Hemisphere

Science.gov (United States)

Tilmes, S.; Pan, L. L.; Hoor, P.; Atlas, E.; Avery, M. A.; Campos, T.; Christensen, L. E.; Diskin, G. S.; Gao, R.-S.; Herman, R. L.;

Differential impact of flow and mouth leak on oropharyngeal humidification during high-flow nasal cannula: a neonatal bench study.

Science.gov (United States)

Ullrich, Tim Leon; Czernik, Christoph; Bührer, Christoph; Schmalisch, Gerd; Fischer, Hendrik Stefan

2018-03-09

Heated humidification is paramount during neonatal high-flow nasal cannula (HFNC) therapy. However, there is little knowledge about the influence of flow rate and mouth leak on oropharyngeal humidification and temperature. The effect of the Optiflow HFNC on oropharyngeal gas conditioning was investigated at flow rates of 4, 6 and 8 L min -1 with and without mouth leak in a bench model simulating physiological oropharyngeal air conditions during spontaneous breathing. Temperature and absolute humidity (AH) were measured using a digital thermo-hygrosensor. Without mouth leak, oropharyngeal temperature and AH increased significantly with increasing flow (P < 0.001). Mouth leak did not affect this increase up to 6 L min -1 , but at 8 L min -1 , temperature and AH plateaued, and the effect of mouth leak became statistically significant (P < 0.001). Mouth leak during HFNC had a negative impact on oropharyngeal gas conditioning when high flows were applied. However, temperature and AH always remained clinically acceptable.

A new device for 100 per cent humidification of inspired air

Science.gov (United States)

Larsson, Anders; Gustafsson, Ann; Svanborg, Lennart

2000-01-01

Introduction: Devices for active humidification of the inspired air in mechanically ventilated patients cause water condensation in the ventilator tubing, which may become contaminated or interfere with the function of the ventilator. The present study describes and tests the performance of a new humidifier, which is designed to eliminate water condensation. Objectives: To test the performance of the new humidifier at different ventilator settings in a lung model, and to compare this new humidifier with a conventional active humidifier in ventilator-treated critically ill patients. Materials and methods: The humidifier (Humid-Heat; Louis Gibeck AB, Upplands Väsby, Sweden) consists of a supply unit with a microprocessor and a water pump, and a humidification device, which is placed between the Y-piece and the endotracheal tube. The humidification device is based on a hygroscopic heat-moisture exchanger (HME), which absorbs the expired heat and moisture and releases it into the inspired gas. External heat and water are then added to the patient side of the HME, so the inspired gas should reach 100% humidity at 37°C (44 mg H2O/l air). The external water is delivered to the humidification device via a pump onto a wick and then evaporated into the inspired air by an electrical heater. The microprocessor controls the water pump and the heater by an algorithm using the minute ventilation (which is fed into the microprocessor) and the airway temperature measured by a sensor mounted in the flex-tube on the patient side of the humidification device. The performance characteristics were tested in a lung model ventilated with a constant flow (inspiratory:expiratory ratio 1:2, rate 12–20 breaths/min and a minute ventilation of 3–25 l/min) or with a decelerating flow (inspiratory:expiratory ratio 1:2, rate 12–15 breaths/min and a minute ventilation of 4.7–16.4 l/min). The device was also tested prospectively and in a randomized order compared with a conventional active

The influence of biogenic emissions from Africa on tropical tropospheric ozone during 2006: a global modeling study

Directory of Open Access Journals (Sweden)

J. E. Williams

2009-08-01

Full Text Available We have performed simulations using a 3-D global chemistry-transport model to investigate the influence that biogenic emissions from the African continent exert on the composition of the troposphere in the tropical region. For this purpose we have applied two recently developed biogenic emission inventories provided for use in large-scale global models (Granier et al., 2005; Lathière et al., 2006 whose seasonality and temporal distribution for biogenic emissions of isoprene, other volatile organic compounds and NO is markedly different. The use of the 12 year average values for biogenic emissions provided by Lathière et al. (2006 results in an increase in the amount of nitrogen sequestrated into longer lived reservoir compounds which contributes to the reduction in the tropospheric ozone burden in the tropics. The associated re-partitioning of nitrogen between PAN, HNO₃ and organic nitrates also results in a ~5% increase in the loss of nitrogen by wet deposition. At a global scale there is a reduction in the oxidizing capacity of the model atmosphere which increases the atmospheric lifetimes of CH₄ and CO by ~1.5% and ~4%, respectively. Comparisons against a range of different measurements indicate that applying the 12 year average of Lathière et al. (2006 improves the performance of TM4_AMMA for 2006 in the tropics. By the use of sensitivity studies we show that the release of NO from soils in Africa accounts for between ~2–45% of tropospheric ozone in the African troposphere, ~10% in the upper troposphere and between ~5–20% of the tropical tropospheric ozone column over the tropical Atlantic Ocean. The subsequent reduction in OH over the source regions allows enhanced transport of CO out of the region. For biogenic volatile organic C1 to C3 species released from Africa, the effects on tropical tropospheric ozone are rather limited, although this source contributes to the global burden of VOC by between ~2–4% and

Thermal structure of the TTL and its relation to stratospheric-tropospheric exchange of water.

Science.gov (United States)

de La Torre Juárez, M.; Ao, C. O.; Schr\\O der, T. M.; Hermann, R.

2004-12-01

The annual cycle of the TTL fine scale thermal structure is described as captured by GPS radio occultation and the pressure levels of the ECMWF weather analysis. This annual cycle is compared to the annual cycle in water concentrations at the upper troposphere/lower stratosphere measured by HALOE. It is found that the saturation mixing ratios at the Cold Point Tropopause temperatures are consistent and sligthly below HALOE values with some temporal lag. This suggests that if dehydration mechanisms other than those associated with slow vertical asscent are working effectively, they must be counterbalanced by other hydration mechanisms. A comparison between saturation mixing ratios at the temperatures captured by GPS radio occultation and HALOE concentrations of water vapor show an annual cycle dominated by supersaturation in the boreal winter months, when the upward mass fluxes are larger, and subsaturation in the summer. The longitudinal dependence of these cycles is discussed and so is its possible implication for the seasonality of statospheric-tropospheric exchange of water.

Follow-up study of workers in a nylon carpet yarn plant after remedial actions taken against a contaminated humidification system

NARCIS (Netherlands)

Pal, TM; Groothoff, JW; Post, D; de Monchy, JGR

Objective: To investigate the effectiveness of remedial actions taken against a contaminated humidification system, after an outbreak of humidifier disease in a nylon carpet yam plant. Methods: Two and 6 years after modification, a follow-up investigation of a strati tied (age, smoking habits)

Prevention of hypothermia in patients undergoing orthotopic liver transplantation using the humigard® open surgery humidification system: a prospective randomized pilot and feasibility clinical trial.

Science.gov (United States)

Weinberg, Laurence; Huang, Andrew; Alban, Daniel; Jones, Robert; Story, David; McNicol, Larry; Pearce, Brett

2017-01-23

Perioperative thermal disturbances during orthotopic liver transplantation (OLT) are common. We hypothesized that in patients undergoing OLT the use of a humidified high flow CO 2 warming system maintains higher intraoperative temperatures when compared to standardized multimodal strategies to maintain thermoregulatory homeostasis. We performed a randomized pilot study in adult patients undergoing primary OLT. Participants were randomized to receive either open wound humidification with a high flow CO 2 warming system in addition to standard care (Humidification group) or to standard care alone (Control group). The primary end point was nasopharyngeal core temperature measured 5 min immediately prior to reperfusion of the donor liver (Stage 3 - 5 min). Secondary endpoints included intraoperative PaCO 2 , minute ventilation and the use of vasoconstrictors. Eleven patients were randomized to each group. Both groups were similar for age, body mass index, MELD, SOFA and APACHE II scores, baseline temperature, and duration of surgery. Immediately prior to reperfusion (Stage 3 - 5 min) the mean (SD) core temperature was higher in the Humidification Group compared to the Control Group: 36.0 °C (0.13) vs. 35.4 °C (0.22), p = 0.028. Repeated measured ANOVA showed that core temperatures over time during the stages of the transplant were higher in the Humidification Group compared to the Control Group (p < 0.0001). There were no significant differences in the ETCO 2 , PaCO 2 , minute ventilation, or inotropic support. The humidified high flow CO 2 warming system was superior to standardized multimodal strategies in maintaining normothermia in patients undergoing OLT. Use of the device was feasible and did not interfere with any aspects of surgery. A larger study is needed to investigate if the improved thermoregulation observed is associated with improved patient outcomes. ACTRN12616001631493 . Retrospectively registered 25 November 2016.

Insufficient Humidification of Respiratory Gases in Patients Who Are Undergoing Therapeutic Hypothermia at a Paediatric and Adult Intensive Care Unit.

Science.gov (United States)

Tanaka, Yukari; Iwata, Sachiko; Kinoshita, Masahiro; Tsuda, Kennosuke; Tanaka, Shoichiro; Hara, Naoko; Shindou, Ryota; Harada, Eimei; Kijima, Ryouji; Yamaga, Osamu; Ohkuma, Hitoe; Ushijima, Kazuo; Sakamoto, Teruo; Yamashita, Yushiro; Iwata, Osuke

2017-01-01

For cooled newborn infants, humidifier settings for normothermic condition provide excessive gas humidity because absolute humidity at saturation is temperature-dependent. To assess humidification of respiratory gases in patients who underwent moderate therapeutic hypothermia at a paediatric/adult intensive care unit, 6 patients were studied over 9 times. Three humidifier settings, 37-default (chamber-outlet, 37°C; Y-piece, 40°C), 33.5-theoretical (chamber-outlet, 33.5°C; Y-piece, 36.5°C), and 33.5-adjusted (optimised setting to achieve saturated vapour at 33.5°C using feedback from a thermohygrometer), were tested. Y-piece gas temperature/humidity and the incidence of high (>40.6 mg/L) and low (humidification were highlighted in patients cooled at a paediatric/adult intensive care unit. Y-piece gas conditions can be controlled to the theoretically optimal level by adjusting the setting guided by Y-piece gas temperature/humidity.

Evaluating the lower-tropospheric COSMIC GPS radio occultation sounding quality over the Arctic

Science.gov (United States)

Yu, Xiao; Xie, Feiqin; Ao, Chi O.

2018-04-01

Lower-tropospheric moisture and temperature measurements are crucial for understanding weather prediction and climate change. Global Positioning System radio occultation (GPS RO) has been demonstrated as a high-quality observation technique with high vertical resolution and sub-kelvin temperature precision from the upper troposphere to the stratosphere. In the tropical lower troposphere, particularly the lowest 2 km, the quality of RO retrievals is known to be degraded and is a topic of active research. However, it is not clear whether similar problems exist at high latitudes, particularly over the Arctic, which is characterized by smooth ocean surface and often negligible moisture in the atmosphere. In this study, 3-year (2008-2010) GPS RO soundings from COSMIC (Constellation Observing System for Meteorology, Ionosphere, and Climate) over the Arctic (65-90° N) show uniform spatial sampling with average penetration depth within 300 m above the ocean surface. Over 70 % of RO soundings penetrate deep into the lowest 300 m of the troposphere in all non-summer seasons. However, the fraction of such deeply penetrating profiles reduces to only about 50-60 % in summer, when near-surface moisture and its variation increase. Both structural and parametric uncertainties of GPS RO soundings were also analyzed. The structural uncertainty (due to different data processing approaches) is estimated to be within ˜ 0.07 % in refractivity, ˜ 0.72 K in temperature, and ˜ 0.05 g kg-1 in specific humidity below 10 km, which is derived by comparing RO retrievals from two independent data processing centers. The parametric uncertainty (internal uncertainty of RO sounding) is quantified by comparing GPS RO with near-coincident radiosonde and European Centre for Medium-Range Weather Forecasts (ECMWF) ERA-Interim profiles. A systematic negative bias up to ˜ 1 % in refractivity below 2 km is only seen in the summer, which confirms the moisture impact on GPS RO quality.

The influence of tropospheric static stability on upper-level frontogenesis

OpenAIRE

Saute, Marcel

2011-01-01

Upper-level frontogenesis in an inviscid, dry and adiabatic fluid forced by confluence is investigated by means of a two-dimensional semi-geostrophic model using the specific volume as an isentropic vertical coordinate. The initial conditions are specified given an analytical continuous potential vorticity field in the presence of a temperature contrast at the ground, the lower boundary condition requiring an appropriate treatment because the ground intersects the first levels of the model. T...

Tropospheric mercury vertical profiles between 500 and 10 000 m in central Europe

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A. Weigelt

2016-03-01

Full Text Available The knowledge of the vertical distribution of atmospheric mercury (Hg plays an important role in determining the transport and cycling of mercury. However, measurements of the vertical distribution are rare, because airborne measurements are expensive and labour intensive. Consequently, only a few vertical Hg profile measurements have been reported since the 1970s. Besides the Civil Aircraft for the Regular Investigation of the atmosphere Based on an Instrument Container (CARIBIC observations, the latest vertical profile over Europe was measured in 1996. Within the Global Mercury Observation System (GMOS project, four vertical profiles were taken on board research aircraft (CASA-212 in August 2013 in background air over different locations in Slovenia and Germany. Each vertical profile consists of at least seven 5 min horizontal flight sections from 500 m above ground to 3000 m a.s.l. Gaseous elemental mercury (GEM and total gaseous mercury (TGM were measured with Tekran 2537X and Tekran 2537B analysers. In addition to the mercury measurements, SO2, CO, O3, NO, and NO2, basic meteorological parameters (pressure, temperature, relative humidity have been measured. Additional ground-based mercury measurements at the GMOS master site in Waldhof, Germany and measurements onboard the CARIBIC passenger aircraft were used to extend the profile to the ground and upper troposphere respectively. No vertical gradient was found inside the well-mixed boundary layer (variation of less than 0.1 ng m−3 at different sites, with GEM varying from location to location between 1.4 and 1.6 ng m−3 (standard temperature and pressure, STP: T  =  273.15 K, p  =  1013.25 hPa. At all locations GEM dropped to 1.3 ng m−3 (STP when entering the free troposphere and remained constant at higher altitudes. The combination of the vertical profile, measured on 21 August 2013 over Leipzig, Germany, with the CARIBIC measurements during ascent and descent to

Homepage for the Global Tropospheric Experiment

Science.gov (United States)

Ward, Eugene

1995-01-01

The objective of my NASA summer research project was to create a homepage to describe and present results from the NASA Global Tropospheric Experiment (GTE). The GTE is a major component of NASA's Tropospheric Chemistry Program and is managed in the Atmospheric Studies Branch, Atmospheric Sciences Division at the NASA Langley Research Center.

Assessment of atmospheric processes driving ozone variations in the subtropical North Atlantic free troposphere

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E. Cuevas

2013-02-01

Full Text Available An analysis of the 22-yr ozone (O₃ series (1988–2009 at the subtropical high mountain Izaña~station (IZO; 2373 m a.s.l., representative of free troposphere (FT conditions, is presented. Diurnal and seasonal O₃ variations as well as the O₃ trend (0.19 ± 0.05 % yr⁻¹ or 0.09 ppbv yr⁻¹, are assessed. A climatology of O₃ transport pathways using backward trajectories shows that higher O₃ values are associated with air masses travelling above 4 km altitude from North America and North Atlantic Ocean, while low O₃ is transported from the Saharan continental boundary layer (CBL. O₃ data have been compared with PM₁₀, ²¹⁰Pb, ⁷Be, potential vorticity (PV and carbon monoxide (CO. A clear negative logarithmic relationship was observed between PM₁₀ and surface O₃ for all seasons. A similar relationship was found between O₃ and ²¹⁰Pb. The highest daily O₃ values (90th percentile are observed in spring and in the first half of summer time. A positive correlation between O₃ and PV, and between O₃ and ⁷Be is found throughout the year, indicating that relatively high surface O₃ values at IZO originate from the middle and upper troposphere. We find a good correlation between O₃ and CO in winter, supporting the hypothesis of long-range transport of photochemically generated O₃ from North America. Aged air masses, in combination with sporadic inputs from the upper troposphere, are observed in spring, summer and autumn. In summer time high O₃ values seem to be the result of stratosphere-to-troposphere (STT exchange processes in regions neighbouring the Canary Islands. Since 1995–1996, the North Atlantic Oscillation has changed from a predominantly high positive phase to alternating between negative

Uncertainty in the Future Distribution of Tropospheric Ozone over West Africa due to Variability in Anthropogenic Emissions Estimates between 2025 and 2050

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J. E. Williams

2011-01-01

Full Text Available Particle and trace gas emissions due to anthropogenic activity are expected to increase significantly in West Africa over the next few decades due to rising population and more energy intensive lifestyles. Here we perform 3D global chemistry-transport model calculations for 2025 and 2050 using both a “business-as-usual” (A1B and “clean economy” (B1 future anthropogenic emission scenario to focus on the changes in the distribution and uncertainties associated with tropospheric O3 due to the various projected emission scenarios. When compared to the present-day troposphere we find that there are significant increases in tropospheric O3 for the A1B emission scenario, with the largest increases being located in the lower troposphere near the source regions and into the Sahel around 15–20°N. In part this increase is due to more efficient NOx re-cycling related to increases in the background methane concentrations. Examining the uncertainty across different emission inventories reveals that there is an associated uncertainty of up to ~20% in the predicted increases at 2025 and 2050. For the upper troposphere, where increases in O3 have a more pronounced impact on radiative forcing, the uncertainty is influenced by transport of O3 rich air from Asia on the Tropical Easterly Jet.

Does acetone react with HO2 in the upper-troposphere?

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J. Lelieveld

2012-02-01

Full Text Available Recent theoretical calculations showed that reaction with HO2 could be an important sink for acetone (CH3C(OCH3 and source of acetic acid (CH3C(OOH in cold parts of the atmosphere (e.g. the tropopause region. This work details studies of HO2 + CH3C(OCH3 (CH32C(OHOO (R1 in laboratory-based and theoretical chemistry experiments; the atmospheric significance of Reaction (R1 was assessed in a global 3-D chemical model. Pulsed laser-kinetic experiments were conducted, for the first time, at the low-temperatures representative of the tropopause. Reaction with NO converted HO2 to OH for detection by laser induced fluorescence. Reduced yields of OH at T 2 by CH3C(OCH3 with a forward rate coefficient greater than 2 × 10−12 cm3 molecule−1 s−1. No evidence for Reaction (R1 was observed at T > 230 K, probably due to rapid thermal dissociation back to HO2 + CH3C(OCH3. Numerical simulations of the data indicate that these experiments were sensitive to only (R1a HO2-CH3C(OCH3 complex formation, the first step in (R1. Rearrangement (R1b of the complex to form peroxy radicals, and hence the atmospheric significance of (R1 has yet to be rigorously verified by experiment. Results from new quantum chemical calculations indicate that K1 is characterised by large uncertainties of at least an order of magnitude at T 3C(OCH3 near the tropopause, it cannot explain observations of CH3C(OOH throughout the troposphere.

Theoretical investigation of solar humidification-dehumidification desalination system using parabolic trough concentrators

International Nuclear Information System (INIS)

Mohamed, A.M.I.; El-Minshawy, N.A.

2011-01-01

Highlights: → We evaluated the performance of sea water HDD system powered by solar PTC. → The proposed design to the expected desalination plant performance was introduced. → The collector thermal efficiency was a function of solar radiation value. → The highest fresh water productivity is found to be in the summer season. → The production time reaches 42% of the day time in the summer season. - Abstract: This paper deals with the status of solar energy as a clean and renewable energy applications in desalination. The object of this research is to theoretically investigate the principal operating parameters of a proposed desalination system based on air humidification-dehumidification principles. A parabolic trough solar collector is adapted to drive and optimize the considered desalination system. A test set-up of the desalination system was designed and a theoretical simulation model was constructed to evaluate the performance and productivity of the proposed solar humidification-dehumidification desalination system. The theoretical simulation model was developed in which the thermodynamic models of each component of the considered were set up respectively. The study showed that, parabolic trough solar collector is the suitable to drive the proposed desalination system. A comparison study had been presented to show the effect of the different parameters on the performance and the productivity of the system. The productivity of the proposed system showed also an increase with the increase of the day time till an optimum value and then decreased. The highest fresh water productivity is found to be in the summer season, when high direct solar radiation and long solar time are always expected. The production time reaches a maximum value in the summer season, which is 42% of the day.

Some regularities of spatial and time distribution of organogenous material in Upper-Pleistocene and Holocene sediments of Central Asia (from the data of Carbon-isotope dating)

International Nuclear Information System (INIS)

Pshenin, G.N.; Steklenkov, A.P.; Varushchenko, A.N.

1991-01-01

The analysis of space time distribution of ancient organogenous material is carried out through generalization of practically all available at the present time data on radiocarbon dating of Upper-Pleistocene and Holocene sediments in the Middle Asia. The investigations were performed to study the variability of humidification over the specific territory of the Middle Asia within a determined period of time. Three rather clearly limited vertical height intervals are determined by the results of the isotope dating of wood, coal, peat and mollus samples

Sulfate Aerosols from Non-Explosive Volcanoes: Chemical-Radiative Effects in the Troposphere and Lower Stratosphere

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Giovanni Pitari

2016-06-01

Full Text Available SO2 and H2S are the two most important gas-phase sulfur species emitted by volcanoes, with a global amount from non-explosive emissions of the order 10 Tg-S/yr. These gases are readily oxidized forming SO42− aerosols, which effectively scatter the incoming solar radiation and cool the surface. They also perturb atmospheric chemistry by enhancing the NOx to HNO3 heterogeneous conversion via hydrolysis on the aerosol surface of N2O5 and Br-Cl nitrates. This reduces formation of tropospheric O3 and the OH to HO2 ratio, thus limiting the oxidation of CH4 and increasing its lifetime. In addition to this tropospheric chemistry perturbation, there is also an impact on the NOx heterogeneous chemistry in the lower stratosphere, due to vertical transport of volcanic SO2 up to the tropical tropopause layer. Furthermore, the stratospheric O3 formation and loss, as well as the NOx budget, may be slightly affected by the additional amount of upward diffused solar radiation and consequent increase of photolysis rates. Two multi-decadal time-slice runs of a climate-chemistry-aerosol model have been designed for studying these chemical-radiative effects. A tropopause mean global net radiative flux change (RF of −0.23 W·m−2 is calculated (including direct and indirect aerosol effects with a 14% increase of the global mean sulfate aerosol optical depth. A 5–15 ppt NOx decrease is found in the mid-troposphere subtropics and mid-latitudes and also from pole to pole in the lower stratosphere. The tropospheric NOx perturbation triggers a column O3 decrease of 0.5–1.5 DU and a 1.1% increase of the CH4 lifetime. The surface cooling induced by solar radiation scattering by the volcanic aerosols induces a tropospheric stabilization with reduced updraft velocities that produce ice supersaturation conditions in the upper troposphere. A global mean 0.9% decrease of the cirrus ice optical depth is calculated with an indirect RF of −0.08 W·m−2.

Impact of climate variability on tropospheric ozone

International Nuclear Information System (INIS)

Grewe, Volker

2007-01-01

A simulation with the climate-chemistry model (CCM) E39/C is presented, which covers both the troposphere and stratosphere dynamics and chemistry during the period 1960 to 1999. Although the CCM, by its nature, is not exactly representing observed day-by-day meteorology, there is an overall model's tendency to correctly reproduce the variability pattern due to an inclusion of realistic external forcings, like observed sea surface temperatures (e.g. El Nino), major volcanic eruption, solar cycle, concentrations of greenhouse gases, and Quasi-Biennial Oscillation. Additionally, climate-chemistry interactions are included, like the impact of ozone, methane, and other species on radiation and dynamics, and the impact of dynamics on emissions (lightning). However, a number of important feedbacks are not yet included (e.g. feedbacks related to biogenic emissions and emissions due to biomass burning). The results show a good representation of the evolution of the stratospheric ozone layer, including the ozone hole, which plays an important role for the simulation of natural variability of tropospheric ozone. Anthropogenic NO x emissions are included with a step-wise linear trend for each sector, but no interannual variability is included. The application of a number of diagnostics (e.g. marked ozone tracers) allows the separation of the impact of various processes/emissions on tropospheric ozone and shows that the simulated Northern Hemisphere tropospheric ozone budget is not only dominated by nitrogen oxide emissions and other ozone pre-cursors, but also by changes of the stratospheric ozone budget and its flux into the troposphere, which tends to reduce the simulated positive trend in tropospheric ozone due to emissions from industry and traffic during the late 80s and early 90s. For tropical regions the variability in ozone is dominated by variability in lightning (related to ENSO) and stratosphere-troposphere exchange (related to Northern Hemisphere Stratospheric

EOF analysis of COSMIC observations on the global zonal mean temperature structure of the Upper Troposphere and Lower Stratosphere from 2007 to 2013

Science.gov (United States)

Salinas, Cornelius Csar Jude H.; Chang, Loren C.

2018-06-01

This work presents the results of a Conventional Empirical Orthogonal Function Analysis on daily global zonal mean temperature profiles in the Upper Troposphere and Lower Stratosphere (15-35 km), as measured by the FORMOSAT-3/COSMIC mission from January 2007 to June 2013. For validation, results were compared with ERA-Interim reanalysis. Results show that, the leading global EOF mode (27%) from COSMIC is consistent with temperature anomalies due to the tropical cooling associated with boreal winter Sudden Stratospheric Warmings (SSW). The second global EOF mode from COSMIC (15.3%) is consistent with temperature anomalies due to the Quasi-biennial Oscillation (QBO). The third global mode from COSMIC (10.9%) is consistent with temperature anomalies due to the El Nino Southern Oscillation. This work also shows that the second northern hemisphere EOF mode from COSMIC (16.8%) is consistent with temperature anomalies due Rossby-wave breaking (RWB) which is expected to only be resolved by a high vertical and temporal resolution dataset like COSMIC. Our work concludes that the use of a high vertical and temporal resolution dataset like COSMIC yields non-seasonal EOF modes that are consistent with relatively more intricate temperature anomalies due to the SSW, QBO, ENSO and RWB.

Impact of humidification and nebulization during expiratory limb protection: an experimental bench study.

Science.gov (United States)

Tonnelier, Alexandre; Lellouche, François; Bouchard, Pierre Alexandre; L'Her, Erwan

2013-08-01

Different filtering devices are used during mechanical ventilation to avoid dysfunction of flow and pressure transducers or for airborne microorganisms containment. Water condensates, resulting from the use of humidifiers, but also residual nebulization particles may have a major influence on expiratory limb resistance. To evaluate the influence of nebulization and active humidification on the resistance of expiratory filters. A respiratory system analog was constructed using a test lung, an ICU ventilator, heated humidifiers, and a piezoelectric nebulizer. Humidifiers were connected to different types of circuits (unheated, mono-heated, new-generation and old-generation bi-heated). Five filter types were evaluated: electrostatic, heat-and-moisture exchanger, standard, specific, and internal heated high-efficiency particulate air [HEPA] filter. Baseline characteristics were obtained from each dry filter. Differential pressure measurements were carried out after 24 hours of continuous in vitro use for each condition, and after 24 hours of use with an old-generation bi-heated circuit without nebulization. While using unheated circuits, measurements had to be interrupted before 24 hours for all the filtering devices except the internal heated HEPA filter. The heat-and-moisture exchangers occluded before 24 hours with the unheated and mono-heated circuits. The circuit type, nebulization practice, and duration of use did not influence the internal heated HEPA filter resistance. Expiratory limb filtration is likely to induce several major adverse events. Expiratory filter resistance increase is due mainly to the humidification circuit type, rather than to nebulization. If filtration is mandatory while using an unheated circuit, a dedicated filter should be used for ≤ 24 hours, or a heated HEPA for a longer duration.

Free-tropospheric BrO investigations based on GOME

Science.gov (United States)

Post, P.; van Roozendael, M.; Backman, L.; Damski, J.; Thölix, L.; Fayt, C.; Taalas, P.

2003-04-01

Bromine compounds contribute significantly to the stratospheric ozone depletion. However measurements of most bromine compounds are sparse or non-existent, and experimental studies essentially rely on BrO observations. The differences between balloon and ground based measurements of stratospheric BrO columns and satellite total column measurements are too large to be explained by measurement uncertainties. Therefore, it has been assumed that there is a concentration of BrO in the free troposphere of about 1-3 ppt. In a previous work, we have calculated the tropospheric BrO abundance as the difference between total BrO and stratospheric BrO columns. The total vertical column densities of BrO are extracted from GOME measurements using IASB-BIRA algorithms. The stratospheric amount has been calculated using chemical transport models (CTM). Results from SLIMCAT and FinROSE simulations are used for this purpose. SLIMCAT is a widely used 3D CTM that has been tested against balloon measurements. FinROSE is a 3D CTM developed at FMI. We have tried several different tropospheric BrO profiles. Our results show that a profile with high BrO concentrations in the boundary layer usually gives unrealistically high tropospheric column values over areas of low albedo (like oceans). This suggests that the tropospheric BrO would be predominantly distributed in the free troposphere. In this work, attempts are made to identify the signature of a free tropospheric BrO content when comparing cloudy and non-cloudy scenes. The possible impact of orography on measured BrO columns is also investigated.

Performance analysis of NOAA tropospheric signal delay model

International Nuclear Information System (INIS)

Ibrahim, Hassan E; El-Rabbany, Ahmed

2011-01-01

Tropospheric delay is one of the dominant global positioning system (GPS) errors, which degrades the positioning accuracy. Recent development in tropospheric modeling relies on implementation of more accurate numerical weather prediction (NWP) models. In North America one of the NWP-based tropospheric correction models is the NOAA Tropospheric Signal Delay Model (NOAATrop), which was developed by the US National Oceanic and Atmospheric Administration (NOAA). Because of its potential to improve the GPS positioning accuracy, the NOAATrop model became the focus of many researchers. In this paper, we analyzed the performance of the NOAATrop model and examined its effect on ionosphere-free-based precise point positioning (PPP) solution. We generated 3 year long tropospheric zenith total delay (ZTD) data series for the NOAATrop model, Hopfield model, and the International GNSS Services (IGS) final tropospheric correction product, respectively. These data sets were generated at ten IGS reference stations spanning Canada and the United States. We analyzed the NOAATrop ZTD data series and compared them with those of the Hopfield model. The IGS final tropospheric product was used as a reference. The analysis shows that the performance of the NOAATrop model is a function of both season (time of the year) and geographical location. However, its performance was superior to the Hopfield model in all cases. We further investigated the effect of implementing the NOAATrop model on the ionosphere-free-based PPP solution convergence and accuracy. It is shown that the use of the NOAATrop model improved the PPP solution convergence by 1%, 10% and 15% for the latitude, longitude and height components, respectively

Five year follow-up of a randomized controlled trial on warming and humidification of insufflation gas in laparoscopic colonic surgery--impact on small bowel obstruction and oncologic outcomes.

Science.gov (United States)

Sammour, Tarik; Hill, Andrew G

2015-04-01

Warming and humidification of insufflation gas has been shown to reduce adhesion formation and tumor implantation in the laboratory setting, but clinical evidence is lacking. We aimed to test the hypothesis that warming and humidification of insufflation CO2 would lead to reduced adhesion formation, and improve oncologic outcomes in laparoscopic colonic surgery. This was a 5-year follow-up of a multicenter, double-blinded, randomized, controlled trial investigating warming and humidification of insufflation gas. The study group received warmed (37°C), humidified (98%) insufflation carbon dioxide, and the control group received standard gas (19°C, 0%). All other aspects of patient care were standardized. Admissions for small bowel obstruction were recorded, as well as whether management was operative or nonoperative. Local and systemic cancer recurrence, 5-year overall survival, and cancer specific survival rates were also recorded. Eighty two patients were randomized, with 41 in each arm. Groups were well matched at baseline. There was no difference between the study and control groups in the rate of clinical small bowel obstruction (5.7% versus 0%, P 0.226); local recurrence (6.5% versus 6.1%, P 1.000); overall survival (85.7% versus 82.1%, P 0.759); or cancer-specific survival (90.3% versus 87.9%, P 1.000). Warming and humidification of insufflation CO2 in laparoscopic colonic surgery does not appear to confer a clinically significant long term benefit in terms of adhesion reduction or oncological outcomes, although a much larger randomized controlled trial (RCT) would be required to confirm this. ClinicalTrials.gov Trial identifier: NCT00642005; US National Library of Medicine, 8600 Rockville Pike, Bethesda, MD 20894, USA.

Five Year Follow-Up of a Randomized Controlled Trial on Warming and Humidification of Insufflation Gas in Laparoscopic Colonic Surgery—Impact on Small Bowel Obstruction and Oncologic Outcomes

Science.gov (United States)

Sammour, Tarik; Hill, Andrew G.

2015-01-01

Warming and humidification of insufflation gas has been shown to reduce adhesion formation and tumor implantation in the laboratory setting, but clinical evidence is lacking. We aimed to test the hypothesis that warming and humidification of insufflation CO2 would lead to reduced adhesion formation, and improve oncologic outcomes in laparoscopic colonic surgery. This was a 5-year follow-up of a multicenter, double-blinded, randomized, controlled trial investigating warming and humidification of insufflation gas. The study group received warmed (37°C), humidified (98%) insufflation carbon dioxide, and the control group received standard gas (19°C, 0%). All other aspects of patient care were standardized. Admissions for small bowel obstruction were recorded, as well as whether management was operative or nonoperative. Local and systemic cancer recurrence, 5-year overall survival, and cancer specific survival rates were also recorded. Eighty two patients were randomized, with 41 in each arm. Groups were well matched at baseline. There was no difference between the study and control groups in the rate of clinical small bowel obstruction (5.7% versus 0%, P 0.226); local recurrence (6.5% versus 6.1%, P 1.000); overall survival (85.7% versus 82.1%, P 0.759); or cancer-specific survival (90.3% versus 87.9%, P 1.000). Warming and humidification of insufflation CO2 in laparoscopic colonic surgery does not appear to confer a clinically significant long term benefit in terms of adhesion reduction or oncological outcomes, although a much larger randomized controlled trial (RCT) would be required to confirm this. ClinicalTrials.gov Trial identifier: NCT00642005; US National Library of Medicine, 8600 Rockville Pike, Bethesda, MD 20894, USA. PMID:25875541

Impact of the new HNO3-forming channel of the HO2+NO reaction on tropospheric HNO3, NOx, HOx and ozone

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A. Kukui

2008-07-01

Full Text Available We have studied the impact of the recently observed reaction NO+HO2→HNO3 on atmospheric chemistry. A pressure and temperature-dependent parameterisation of this minor channel of the NO+HO2→NO2+OH reaction has been included in both a 2-D stratosphere-troposphere model and a 3-D tropospheric chemical transport model (CTM. Significant effects on the nitrogen species and hydroxyl radical concentrations are found throughout the troposphere, with the largest percentage changes occurring in the tropical upper troposphere (UT. Including the reaction leads to a reduction in NOx everywhere in the troposphere, with the largest decrease of 25% in the tropical and Southern Hemisphere UT. The tropical UT also has a corresponding large increase in HNO3 of 25%. OH decreases throughout the troposphere with the largest reduction of over 20% in the tropical UT. The mean global decrease in OH is around 13%, which is very large compared to the impact that typical photochemical revisions have on this modelled quantity. This OH decrease leads to an increase in CH4 lifetime of 5%. Due to the impact of decreased NOx on the OH:HO2 partitioning, modelled HO2 actually increases in the tropical UT on including the new reaction. The impact on tropospheric ozone is a decrease in the range 5 to 12%, with the largest impact in the tropics and Southern Hemisphere. Comparison with observations shows that in the region of largest changes, i.e. the tropical UT, the inclusion of the new reaction tends to degrade the model agreement. Elsewhere the model comparisons are not able to critically assess the impact of including this reaction. Only small changes are calculated in the minor species distributions in the stratosphere.

Solar Desalination by Humidification-Dehumidification of Air

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Moumouh J.

2018-01-01

Full Text Available The importance of supplying potable water can hardly be overstressed. In many arid zones, coastal or inlands, seawater or brackish water desalination may be the only solution to the shortage of fresh water. The process based on humidification-dehumidification of air (HDH principle mimic the natural water cycle. HDH technique has been subjected to many studies in recent years due to the low temperature, renewable energy use, simplicity, low cost installation and operation. An experimental test set-up has been fabricated and assembled. The prototype equipped with appropriate measuring and controlling devices. Detailed experiments have been carried out at various operating conditions. The heat and mass transfer coefficients have been obtained experimentally. The results of the investigation have shown that the system productivity increases with the increase in the mass flow rate of water through the unit. Water temperature at condenser exit increases linearly with water temperature at humidifier inlet and it decreases as water flow rate increases. HDH desalination systems realised on also work at atmospheric pressure; hence they do not need mechanical energy except for circulation pumps and fans. These kinds of systems are suitable for developing countries. The system is modular, it is possible to increase productivity with additional solar collectors and additional HDH cycles.

NASA's Upper Atmosphere Research Program (UARP) and Atmospheric Chemistry Modeling and Analysis Program (ACMAP): Research Summaries 1997-1999

Science.gov (United States)

Kurylo, M. J.; DeCola, P. L.; Kaye, J. A.

2000-01-01

Under the mandate contained in the FY 1976 NASA Authorization Act, the National Aeronautics and Space Administration (NASA) has developed and is implementing a comprehensive program of research, technology development, and monitoring of the Earth's upper atmosphere, with emphasis on the upper troposphere and stratosphere. This program aims at expanding our chemical and physical understanding to permit both the quantitative analysis of current perturbations as well as the assessment of possible future changes in this important region of our environment. It is carried out jointly by the Upper Atmosphere Research Program (UARP) and the Atmospheric Chemistry Modeling and Analysis Program (ACMAP), both managed within the Research Division in the Office of Earth Science at NASA. Significant contributions to this effort have also been provided by the Atmospheric Effects of Aviation Project (AEAP) of NASA's Office of Aero-Space Technology. The long-term objectives of the present program are to perform research to: understand the physics, chemistry, and transport processes of the upper troposphere and the stratosphere and their control on the distribution of atmospheric chemical species such as ozone; assess possible perturbations to the composition of the atmosphere caused by human activities and natural phenomena (with a specific emphasis on trace gas geographical distributions, sources, and sinks and the role of trace gases in defining the chemical composition of the upper atmosphere); understand the processes affecting the distributions of radiatively active species in the atmosphere, and the importance of chemical-radiative-dynamical feedbacks on the meteorology and climatology of the stratosphere and troposphere; and understand ozone production, loss, and recovery in an atmosphere with increasing abundances of greenhouse gases. The current report is composed of two parts. Part 1 summarizes the objectives, status, and accomplishments of the research tasks supported

Experimental particle formation rates spanning tropospheric sulfuric acid and ammonia abundances, ion production rates, and temperatures

CERN Document Server

Kürten, Andreas; Almeida, Joao; Kupiainen-Määttä, Oona; Dunne, Eimear M.; Duplissy, Jonathan; Williamson, Christina; Barmet, Peter; Breitenlechner, Martin; Dommen, Josef; Donahue, Neil M.; Flagan, Richard C.; Franchin, Alessandro; Gordon, Hamish; Hakala, Jani; Hansel, Armin; Heinritzi, Martin; Ickes, Luisa; Jokinen, Tuija; Kangasluoma, Juha; Kim, Jaeseok; Kirkby, Jasper; Kupc, Agnieszka; Lehtipalo, Katrianne; Leiminger, Markus; Makhmutov, Vladimir; Onnela, Antti; Ortega, Ismael K.; Petäjä, Tuukka; Praplan, Arnaud P.; Riccobono, Francesco; Rissanen, Matti P.; Rondo, Linda; Schnitzhofer, Ralf; Schobesberger, Siegfried; Smith, James N.; Steiner, Gerhard; Stozhkov, Yuri; Tomé, António; Tröstl, Jasmin; Tsagkogeorgas, Georgios; Wagner, Paul E.; Wimmer, Daniela; Ye, Penglin; Baltensperger, Urs; Carslaw, Ken; Kulmala, Markku; Curtius, Joachim

2016-01-01

Binary nucleation of sulfuric acid and water as well as ternary nucleation involving ammonia arethought to be the dominant processes responsible for new particle formation (NPF) in the cold temperaturesof the middle and upper troposphere. Ions are also thought to be important for particle nucleation inthese regions. However, global models presently lack experimentally measured NPF rates under controlledlaboratory conditions and so at present must rely on theoretical or empirical parameterizations. Here withdata obtained in the European Organization for Nuclear Research CLOUD (Cosmics Leaving OUtdoor Droplets)chamber, we present the first experimental survey of NPF rates spanning free tropospheric conditions. Theconditions during nucleation cover a temperature range from 208 to 298 K, sulfuric acid concentrationsbet ween 5 × 105and 1 × 109cm3, and ammonia mixing ratios from zero added ammonia, i.e., nominally purebinary, to a maximum of ~1400 parts per trillion by volume (pptv). We performed nucleation s...

Sources of tropospheric ozone along the Asian Pacific Rim: An analysis of ozonesonde observations

Science.gov (United States)

Liu, Hongyu; Jacob, Daniel J.; Chan, Lo Yin; Oltmans, Samuel J.; Bey, Isabelle; Yantosca, Robert M.; Harris, Joyce M.; Duncan, Bryan N.; Martin, Randall V.

2002-11-01

The sources contributing to tropospheric ozone over the Asian Pacific Rim in different seasons are quantified by analysis of Hong Kong and Japanese ozonesonde observations with a global three-dimensional (3-D) chemical transport model (GEOS-CHEM) driven by assimilated meteorological observations. Particular focus is placed on the extensive observations available from Hong Kong in 1996. In the middle-upper troposphere (MT-UT), maximum Asian pollution influence along the Pacific Rim occurs in summer, reflecting rapid convective transport of surface pollution. In the lower troposphere (LT) the season of maximum Asian pollution influence shifts to summer at midlatitudes from fall at low latitudes due to monsoonal influence. The UT ozone minimum and high variability observed over Hong Kong in winter reflects frequent tropical intrusions alternating with stratospheric intrusions. Asian biomass burning makes a major contribution to ozone at pollution influence (pollution influence exceeds European influence in the UT-MT, reflecting the uplift from convection and the warm conveyor belts over the eastern seaboard of North America. African outflow makes a major contribution to ozone in the low-latitude MT-UT over the Pacific Rim during November-April. Lightning influence over the Pacific Rim is minimum in summer due to westward UT transport at low latitudes associated with the Tibetan anticyclone. The Asian outflow flux of ozone to the Pacific is maximum in spring and fall and includes a major contribution from Asian anthropogenic sources year-round.

Global 3-D modeling of atmospheric ozone in the free troposphere and the stratosphere with emphasis on midlatitude regions. Final report

Energy Technology Data Exchange (ETDEWEB)

Brasseur, G.; Tie, X.; Walters, S.

1999-03-01

The authors have used several global chemical/transport models (1) to study the contribution of various physical, chemical, and dynamical processes to the budget of mid-latitude ozone in the stratosphere and troposphere; (2) to analyze the potential mechanisms which are responsible for the observed ozone perturbations at mid-latitudes of the lower stratosphere and in the upper troposphere; (3) to calculate potential changes in atmospheric ozone response to anthropogenic changes (e.g., emission of industrially manufactured CFCs, CO, and NO{sub x}) and to natural perturbations (e.g., volcanic eruptions and biomass burning); and (4) to estimate the impact of these changes on the radiative forcing to the climate system and on the level of UV-B radiation at the surface.

Vertical distribution and sources of tropospheric ozone over South China in spring 2004: Ozonesonde measurements and modeling analysis

Science.gov (United States)

Zhang, Y.; Liu, H.; Crawford, J. H.; Considine, D. B.; Chan, C.; Scientific Team Of Tapto

2010-12-01

The Transport of Air Pollutant and Tropospheric Ozone over China (TAPTO-China) science initiative is a two-year (TAPTO 2004 and 2005) field measurement campaign to help improve our understanding of the physical and chemical processes that control the tropospheric ozone budget over the Chinese subcontinent (including the Asian Pacific rim) and its surrounding SE Asia. In this paper, we use two state-of-the-art 3-D global chemical transport models (GEOS-Chem and Global Modeling Initiative or GMI) to examine the characteristics of vertical distribution and quantify the sources of tropospheric ozone by analysis of TAPTO in-situ ozonesonde data obtained at five stations in South China during spring (April and May) 2004: Lin’an (30.30N, 119.75E), Tengchong (25.01N, 98.30E), Taipei (25.0N, 121.3E), Hong Kong (22.21N, 114.30E) and Sanya (18.21N, 110.31E). The observed tropospheric ozone concentrations show strong spatial and temporal variability, which is largely captured by the models. The models simulate well the observed vertical gradients of tropospheric ozone at higher latitudes but are too low at lower latitudes. Model tagged ozone simulations suggest that stratosphere has a large impact on the upper and middle troposphere (UT/MT) at Lin’an and Tengchong. Continental SE Asian biomass burning emissions are maximum in March but still contribute significantly to the photochemical production of tropopheric ozone in South China in early April. Asian anthropogenic emissions are the major contribution to lower tropospheric ozone at all stations. On the other hand, there are episodes of influence from European/North American anthropogenic emissions. For example, model tagged ozone simulations show that over Lin’an in April 2004, stratosphere contributes 20% (13 ppbv) at 5 km, Asian boundary layer contributes 70% (46 ppbv) to ozone in the boundary layer, European boundary layer contributes 5% (3-4 ppbv) at 1.2 km, and North American boundary layer contributes 4.5% (3

Performance Evaluation of Blind Tropospheric Delay correction ...

African Journals Online (AJOL)

lekky

and Temperature 2 wet (GPT2w) models) for tropospheric delay correction, ... In practice, a user often employs a certain troposphere model based on the popularity ... comparisons between some of the models have been carried out in the past for .... prediction of meteorological parameter values, which are then used to ...

Sensitivity of stomatal conductance to soil moisture: implications for tropospheric ozone

Directory of Open Access Journals (Sweden)

A. Anav

2018-04-01

Full Text Available Soil moisture and water stress play a pivotal role in regulating stomatal behaviour of plants; however, in the last decade, the role of water availability has often been neglected in atmospheric chemistry modelling studies as well as in integrated risk assessments, despite the fact that plants remove a large amount of atmospheric compounds from the lower troposphere through stomata. The main aim of this study is to evaluate, within the chemistry transport model CHIMERE, the effect of soil water limitation on stomatal conductance and assess the resulting changes in atmospheric chemistry testing various hypotheses of water uptake by plants in the rooting zone. Results highlight how dry deposition significantly declines when soil moisture is used to regulate the stomatal opening, mainly in the semi-arid environments: in particular, over Europe the amount of ozone removed by dry deposition in one year without considering any soil water limitation to stomatal conductance is about 8.5 TgO3, while using a dynamic layer that ensures that plants maximize the water uptake from soil, we found a reduction of about 10 % in the amount of ozone removed by dry deposition ( ∼  7.7 TgO3. Although dry deposition occurs from the top of canopy to ground level, it affects the concentration of gases remaining in the lower atmosphere, with a significant impact on ozone concentration (up to 4 ppb extending from the surface to the upper troposphere (up to 650 hPa. Our results shed light on the importance of improving the parameterizations of processes occurring at plant level (i.e. from the soil to the canopy as they have significant implications for concentration of gases in the lower troposphere and resulting risk assessments for vegetation or human health.

Sensitivity of stomatal conductance to soil moisture: implications for tropospheric ozone

Science.gov (United States)

Anav, Alessandro; Proietti, Chiara; Menut, Laurent; Carnicelli, Stefano; De Marco, Alessandra; Paoletti, Elena

2018-04-01

Soil moisture and water stress play a pivotal role in regulating stomatal behaviour of plants; however, in the last decade, the role of water availability has often been neglected in atmospheric chemistry modelling studies as well as in integrated risk assessments, despite the fact that plants remove a large amount of atmospheric compounds from the lower troposphere through stomata. The main aim of this study is to evaluate, within the chemistry transport model CHIMERE, the effect of soil water limitation on stomatal conductance and assess the resulting changes in atmospheric chemistry testing various hypotheses of water uptake by plants in the rooting zone. Results highlight how dry deposition significantly declines when soil moisture is used to regulate the stomatal opening, mainly in the semi-arid environments: in particular, over Europe the amount of ozone removed by dry deposition in one year without considering any soil water limitation to stomatal conductance is about 8.5 TgO3, while using a dynamic layer that ensures that plants maximize the water uptake from soil, we found a reduction of about 10 % in the amount of ozone removed by dry deposition ( ˜ 7.7 TgO3). Although dry deposition occurs from the top of canopy to ground level, it affects the concentration of gases remaining in the lower atmosphere, with a significant impact on ozone concentration (up to 4 ppb) extending from the surface to the upper troposphere (up to 650 hPa). Our results shed light on the importance of improving the parameterizations of processes occurring at plant level (i.e. from the soil to the canopy) as they have significant implications for concentration of gases in the lower troposphere and resulting risk assessments for vegetation or human health.

Tropospheric weather influenced by solar wind through atmospheric vertical coupling downward control

Science.gov (United States)

Prikryl, Paul; Bruntz, Robert; Tsukijihara, Takumi; Iwao, Koki; Muldrew, Donald B.; Rušin, Vojto; Rybanský, Milan; Turňa, Maroš; Šťastný, Pavel

2018-06-01

Occurrence of severe weather in the context of solar wind coupling to the magnetosphere-ionosphere-atmosphere (MIA) system is investigated. It is observed that significant snowfall, wind and heavy rain, particularly if caused by low pressure systems in winter, tend to follow arrivals of high-speed solar wind. Previously published statistical evidence that explosive extratropical cyclones in the northern hemisphere tend to occur within a few days after arrivals of high-speed solar wind streams from coronal holes (Prikryl et al., 2009, 2016) is corroborated for the southern hemisphere. Cases of severe weather events are examined in the context of the magnetosphere-ionosphere-atmosphere (MIA) coupling. Physical mechanism to explain these observations is proposed. The leading edge of high-speed solar wind streams is a locus of large-amplitude magneto-hydrodynamic waves that modulate Joule heating and/or Lorentz forcing of the high-latitude lower thermosphere generating medium-scale atmospheric gravity waves that propagate upward and downward through the atmosphere. Simulations of gravity wave propagation in a model atmosphere using the Transfer Function Model (Mayr et al., 1990) reveal that propagating waves originating in the lower thermosphere can excite a spectrum of gravity waves in the lower atmosphere. In spite of significantly reduced amplitudes but subject to amplification upon reflection in the upper troposphere, these gravity waves can provide a lift of unstable air to release instabilities in the troposphere and initiate convection to form cloud/precipitation bands. It is primarily the energy provided by release of latent heat that leads to intensification of storms. These results indicate that vertical coupling in the atmosphere exerts downward control from solar wind to the lower atmospheric levels influencing tropospheric weather development.

Efficient transport of tropospheric aerosol into the stratosphere via the Asian summer monsoon anticyclone

Science.gov (United States)

Yu, Pengfei; Rosenlof, Karen H.; Liu, Shang; Telg, Hagen; Thornberry, Troy D.; Rollins, Andrew W.; Portmann, Robert W.; Bai, Zhixuan; Ray, Eric A.; Duan, Yunjun; Pan, Laura L.; Toon, Owen B.; Bian, Jianchun; Gao, Ru-Shan

2017-07-01

An enhanced aerosol layer near the tropopause over Asia during the June-September period of the Asian summer monsoon (ASM) was recently identified using satellite observations. Its sources and climate impact are presently not well-characterized. To improve understanding of this phenomenon, we made in situ aerosol measurements during summer 2015 from Kunming, China, then followed with a modeling study to assess the global significance. The in situ measurements revealed a robust enhancement in aerosol concentration that extended up to 2 km above the tropopause. A climate model simulation demonstrates that the abundant anthropogenic aerosol precursor emissions from Asia coupled with rapid vertical transport associated with monsoon convection leads to significant particle formation in the upper troposphere within the ASM anticyclone. These particles subsequently spread throughout the entire Northern Hemispheric (NH) lower stratosphere and contribute significantly (˜15%) to the NH stratospheric column aerosol surface area on an annual basis. This contribution is comparable to that from the sum of small volcanic eruptions in the period between 2000 and 2015. Although the ASM contribution is smaller than that from tropical upwelling (˜35%), we find that this region is about three times as efficient per unit area and time in populating the NH stratosphere with aerosol. With a substantial amount of organic and sulfur emissions in Asia, the ASM anticyclone serves as an efficient smokestack venting aerosols to the upper troposphere and lower stratosphere. As economic growth continues in Asia, the relative importance of Asian emissions to stratospheric aerosol is likely to increase.

Effect of tropical cyclones on the stratosphere–troposphere exchange observed using satellite observations over the north Indian Ocean

Directory of Open Access Journals (Sweden)

M. Venkat Ratnam

2016-07-01

Full Text Available Tropical cyclones play an important role in modifying the tropopause structure and dynamics as well as stratosphere–troposphere exchange (STE processes in the upper troposphere and lower stratosphere (UTLS region. In the present study, the impact of cyclones that occurred over the north Indian Ocean during 2007–2013 on the STE processes is quantified using satellite observations. Tropopause characteristics during cyclones are obtained from the Global Positioning System (GPS radio occultation (RO measurements, and ozone and water vapour concentrations in the UTLS region are obtained from Aura Microwave Limb Sounder (MLS satellite observations. The effect of cyclones on the tropopause parameters is observed to be more prominent within 500 km of the centre of the tropical cyclone. In our earlier study, we observed a decrease (increase in the tropopause altitude (temperature up to 0.6 km (3 K, and the convective outflow level increased up to 2 km. This change leads to a total increase in the tropical tropopause layer (TTL thickness of 3 km within 500 km of the centre of cyclone. Interestingly, an enhancement in the ozone mixing ratio in the upper troposphere is clearly noticed within 500 km from the cyclone centre, whereas the enhancement in the water vapour in the lower stratosphere is more significant on the south-east side, extending from 500 to 1000 km away from the cyclone centre. The cross-tropopause mass flux for different intensities of cyclones is estimated and it is found that the mean flux from the stratosphere to the troposphere for cyclonic storms is 0.05 ± 0.29 × 10−3 kg m−2, and for very severe cyclonic storms it is 0.5 ± 1.07 × 10−3 kg m−2. More downward flux is noticed on the north-west and south-west side of the cyclone centre. These results indicate that the cyclones have significant impact in effecting the tropopause structure, ozone and water vapour budget, and

Water recovery and air humidification by condensing the moisture in the outlet gas of a proton exchange membrane fuel cell stack

International Nuclear Information System (INIS)

Wan, Z.M.; Wan, J.H.; Liu, J.; Tu, Z.K.; Pan, M.; Liu, Z.C.; Liu, W.

2012-01-01

Humidification is one of the most important factors for the operation of proton exchange membrane fuel cell (PEMFC). To maintain the membrane at hydrated state, plenty of water is needed for the state-of-the-art of PEMFC technology, especially in large power applications or long time operation. A condenser is introduced to separate liquid water from the air outlet for air self-sufficient in water of the stack in this study. The condensed temperature at the outlet of the condenser and water recovered amount for air self-sufficient in water are investigated theoretically and experimentally. It is shown that the condensed temperature for air self-sufficient in water is irrelevant with the working current of the stack. When the condenser outlet temperature was above the theoretical line, recovery water was not sufficient for the air humidification. On the contrary, it is sufficient while the temperature was below the theoretical line. It is also shown that when the moisture is sufficiently cooled, large amount water can be separated from the outlet gas, and it increased almost linearly with the time. With the introduction of the condenser, the recovered amount of water can easily satisfy the air self-sufficient in water by condensing the outlet gas to a proper temperature. - Highlights: ► We introduce a condenser to separate liquid water from the air outlet in the stack. ► The mechanism of air self-sufficient in water by condensing gas is presented. ► The condensed temperature and water recovered amount are investigated. ► An experiment is present to validate simplicity and feasibility of the criterion. ► The criterion for air humidification is used for choosing the condenser.

Development of an active solar humidification-dehumidification (HDH) desalination system integrated with geothermal energy

International Nuclear Information System (INIS)

Elminshawy, Nabil A.S.; Siddiqui, Farooq R.; Addas, Mohammad F.

2016-01-01

Highlights: • Productivity increases with increasing geothermal water flow rate up to 0.15 kg/s. • Geothermal energy increases productivity by 187–465% when used with solar energy. • Daytime experimental productivity (8AM-5PM) up to 104 L/m"2 was achieved. • Daily experimental productivity (24 h) up to 192 L/m"2 was achieved. • Fresh potable water can be produced at 0.003 USD/L using this desalination setup. - Abstract: This paper investigates the technical and economic feasibility of using a hybrid solar-geothermal energy source in a humidification-dehumidification (HDH) desalination system. The newly developed HDH system is a modified solar still with air blower and condenser used at its inlet and outlet respectively. A geothermal water tank in a temperature range 60–80 °C which imitates a low-grade geothermal energy source was used to supply heat to water inside the humidification chamber. The experiments were conducted in January 2015 under the climatological conditions of Madinah (latitude: 24°33′N, longitude: 39°36′0″E), Saudi Arabia to study the effect of geothermal water temperature and flow rate on the performance and productivity of proposed desalination system. Analytical model was also developed to compare the effect of solar energy and combined solar-geothermal energy on accumulated productivity. Daytime experimental accumulated productivity up to 104 L/m"2 and daily average gained output ratio (GOR) in the range 1.2–1.58 was achieved using the proposed desalination system. Cost of fresh water produced using the presented desalination system is 0.003 USD/L.

Spatial Heterodyne Observations of Water (SHOW) vapour in the upper troposphere and lower stratosphere from a high altitude aircraft: Modelling and sensitivity analysis

Science.gov (United States)

Langille, J. A.; Letros, D.; Zawada, D.; Bourassa, A.; Degenstein, D.; Solheim, B.

2018-04-01

A spatial heterodyne spectrometer (SHS) has been developed to measure the vertical distribution of water vapour in the upper troposphere and the lower stratosphere with a high vertical resolution (∼500 m). The Spatial Heterodyne Observations of Water (SHOW) instrument combines an imaging system with a monolithic field-widened SHS to observe limb scattered sunlight in a vibrational band of water (1363 nm-1366 nm). The instrument has been optimized for observations from NASA's ER-2 aircraft as a proof-of-concept for a future low earth orbit satellite deployment. A robust model has been developed to simulate SHOW ER-2 limb measurements and retrievals. This paper presents the simulation of the SHOW ER-2 limb measurements along a hypothetical flight track and examines the sensitivity of the measurement and retrieval approach. Water vapour fields from an Environment and Climate Change Canada forecast model are used to represent realistic spatial variability along the flight path. High spectral resolution limb scattered radiances are simulated using the SASKTRAN radiative transfer model. It is shown that the SHOW instrument onboard the ER-2 is capable of resolving the water vapour variability in the UTLS from approximately 12 km - 18 km with ±1 ppm accuracy. Vertical resolutions between 500 m and 1 km are feasible. The along track sampling capability of the instrument is also discussed.

Tropospheric VOC measurements by PTR-MS

International Nuclear Information System (INIS)

Hansel, A.; Wisthaler, A.; Graus, M.; Grabmer, W.

2002-01-01

Full text: O 3 is formed photochemically from the photolysis of NO 2 , and because O 3 reacts rapidly with NO these reactions result in a photoequilibrium between NO, NO 2 with no net formation or loss of O 3 , However, in the presence of volatile organic compounds (VOCs), the degradation reactions of VOCs lead to the formation of intermediate peroxy radicals which react with NO, converting NO to NO 2 , which then photolyze to form O 3 . Thus, in order to understand quantitatively tropospheric ozone chemistry, it is necessary to know the VOC distribution within the troposphere as well as VOC fluxes from individual sources. Examples will be presented how the use of Proton Transfer Reaction Mass Spectrometry (PTR-MS) has enhanced our understanding of anthropogenic VOC emissions, biosphere-atmosphere exchange processes, and photochemical processing of both anthropogenic and biogenic VOCs in the troposphere. (author)

Air mass origins and troposphere-to-stratosphere exchange associated with mid-latitude cyclogenesis and tropopause folding inferred from Be-7 measurements

Science.gov (United States)

Kritz, Mark A.; Rosner, Stefan W.; Danielsen, Edwin F.; Selkirk, Henry B.

1991-01-01

The 1984 extratropical mission of NASA's Stratosphere-Troposphere Exchange Project (STEP) studied cross-jet transport in regions of cyclogenesis and tropopause folding. Correlations of Be-7, ozone, water vapor, and potential vorticity measured on a NASA U-2 research aircraft flying in high shear regions above the jet core are indicative of mixing between the cyclonic and the anticyclonic sides of the jet and are consistent with the hypothesis that small-scale entrainments of upper tropospheric air into the lower stratosphere during cyclogenesis are important in maintaining the vertical gradients of Be-7, ozone, water vapor and other trace constituents in the lower few kilometers of the midlatitude stratosphere. Correlations between Be-7, and ozone suggest a lower tropical stratospheric origin for the ozone-poor lamina observed above the jet core.

Troc: a proposed tropospheric sounder for chemistry and climate

Science.gov (United States)

Camy-Peyret, C.

TROC has been submitted to ESA in the last call for proposals of the Earth Explorer Opportunity Missions and its focus is on tropospheric composition and chemistry-climate interactions. The mission objectives of TROC cover four research subjects. Global tropospheric chemistry: perform global measurements from space of tropospheric composition in order to improve our understanding and to constrain models of tropospheric chemistry with emphasis on tropospheric ozone. Pollution: establish the impact of mega cities of industrialised or developing countries by monitoring their pollution plumes. Biomass burning: monitor the chemical species and aerosols injected in the free troposphere during major burning episodes in the intertropical region as well as by major forest fires at other latitudes. Chemistry-climate interactions: quantify on a global scale the distributions and the sources of greenhouse gases like CO2, CH4, O3, N2O and the CFCs. Contribute to demonstration studies for monitoring from space how Montreal and Kyoto protocols are enforced as far as human impacts on atmospheric chemistry and climate are concerned. To fulfil these objectives, passive remote sensing of the troposphere has been selected as the best compromise between technical maturity and multi-species coverage. The main elements of TROC are a Fourier transform infrared (FTIR) instrument and an ultraviolet-visible (UV-vis) spectrometer, both operating in the downward-looking geometry with a 10 km diameter footprint at nadir. An ``intelligent'' pointing mirror coupled to an infrared imager is used to optimise day/night sounding down to the surface. The FTIR instrument covers at 0.1 cm-1 apodised spectral resolution 3 bands from 14 to 3.3 μ m in thermal emission and one band in solar reflected light around 2.3 μ m. The UV-vis instrument covers the regions 290-490 nm (1 nm resolution) and 520-1030 nm (2.5 nm resolution) with 43 array detectors (2 bands × 2 polarizations) in reflected

TROPOSPHERIC AEROSOL PROGRAM, PROGRAM PLAN, MARCH 2001

Energy Technology Data Exchange (ETDEWEB)

SCHWARTZ,S.E.; LUNN,P.

2001-03-01

The goal of Tropospheric Aerosol Program (TAP) will be to develop the fundamental scientific understanding required to construct tools for simulating the life cycle of tropospheric aerosols--the processes controlling their mass loading, composition, and microphysical properties, all as a function of time, location, and altitude. The TAP approach to achieving this goal will be by conducting closely linked field, modeling, laboratory, and theoretical studies focused on the processes controlling formation, growth, transport, and deposition of tropospheric aerosols. This understanding will be represented in models suitable for describing these processes on a variety of geographical scales; evaluation of these models will be a key component of TAP field activities. In carrying out these tasks TAP will work closely with other programs in DOE and in other Federal and state agencies, and with the private sector. A forum to directly work with our counterparts in industry to ensure that the results of this research are translated into products that are useful to that community will be provided by NARSTO (formerly the North American Research Strategy on Tropospheric Ozone), a public/private partnership, whose membership spans government, the utilities, industry, and university researchers in Mexico, the US, and Canada.

Raman Lidar Measurements During the International H2O Project. 2; Instrument Comparisons and Case Studies

Science.gov (United States)

Whiteman, D. N.; Demoz, B.; DiGirolamo, P.; Corner, J.; Veselovskii, I.; Evans, K.; Wang, Z.; Sabatino, D.; Schwemmer, G.; Gentry, B.

2005-01-01

The NASA/GSFC Scanning Raman Lidar (SRL) participated in the International H2O Project (IHOP) that occurred in May and June, 2002 in the midwestern part of the U. S. The SRL system configuration and methods of data analysis were described in part I of this paper. In this second part, comparisons of SRL water vapor measurements and those of chilled mirror radiosonde and LASE airborne water vapor lidar are performed. Two case studies are presented; one for daytime and one for nighttime. The daytime case study is of a convectively driven boundary layer event and is used to characterize the SRL water vapor random error characteristics. The nighttime case study is of a thunderstorm-generated cirrus cloud case that is studied in it s meteorological context. Upper tropospheric humidification due to precipitation from the cirrus cloud is quantified as is the cirrus cloud ice water content and particle depolarization ratio. These detailed cirrus cloud measurements are being used in a cirrus cloud modeling study.

Acetone in theGlobal Troposphere: Its Possible Role as a Global Source of PAN

Science.gov (United States)

Singh, H. B.; Kanakidou, M.

1994-01-01

Oxygenated hydrocarbons are thought to be important components of the atmosphere but, with the exception of formaldehyde, very little about their distribution and fate is known. Aircraft measurements of acetone (CH3COCH3), PAN (CH3CO3NO2) and other organic species (e. g. acetaldehyde, methanol and ethanol) have been performed over the Pacific, the southern Atlantic, and the subarctic atmospheres. Sampled areas extended from 0 to 12 km altitude over latitudes of 70 deg N to 40 deg S. All measurements are based on real time in-situ analysis of cryogenically preconcentrated air samples. Substantial concentrations of these oxygenated species (10-2000 ppt) have been observed at all altitudes and geographical locations in the troposphere. Important sources include, emissions from biomass burning, plant and vegetation, secondary oxidation of primary non-methane hydrocarbons, and man-made emissions. Direct measurements within smoke plumes have been used to estimate the biomass burning source. Photochemistry studies are used to suggest that acetone could provide a major source of peroxyacetyl radicals in the atmosphere and play an important role in sequestering reactive nitrogen. Model calculations show that acetone photolysis contributes significantly to PAN formation in the middle and upper troposphere.

Hydrological controls on the tropospheric ozone greenhouse gas effect

Directory of Open Access Journals (Sweden)

Le Kuai

2017-03-01

Full Text Available The influence of the hydrological cycle in the greenhouse gas (GHG effect of tropospheric ozone (O3 is quantified in terms of the O3longwave radiative effect (LWRE, which is defined as the net reduction of top-of-atmosphere flux due to total tropospheric O3absorption. The O3LWRE derived from the infrared spectral measurements by Aura’s Tropospheric Emission Spectrometer (TES show that the spatiotemporal variation of LWRE is relevant to relative humidity, surface temperature, and tropospheric O3column. The zonally averaged subtropical LWRE is ~0.2 W m-2higher than the zonally averaged tropical LWRE, generally due to lower water vapor concentrations and less cloud coverage at the downward branch of the Hadley cell in the subtropics. The largest values of O3LWRE over the Middle East (>1 W/m2 are further due to large thermal contrasts and tropospheric ozone enhancements from atmospheric circulation and pollution. Conversely, the low O3LWRE over the Inter-Tropical Convergence Zone (on average 0.4 W m-2 is due to strong water vapor absorption and cloudiness, both of which reduce the tropospheric O3absorption in the longwave radiation. These results show that changes in the hydrological cycle due to climate change could affect the magnitude and distribution of ozone radiative forcing.

Profiles of CH4, HDO, H2O, and N2O with improved lower tropospheric vertical resolution from Aura TES radiances

Directory of Open Access Journals (Sweden)

D. Noone

2012-02-01

Full Text Available Thermal infrared (IR radiances measured near 8 microns contain information about the vertical distribution of water vapor (H2O, the water isotopologue HDO, and methane (CH4, key gases in the water and carbon cycles. Previous versions (Version 4 or less of the TES profile retrieval algorithm used a "spectral-window" approach to minimize uncertainty from interfering species at the expense of reduced vertical resolution and sensitivity. In this manuscript we document changes to the vertical resolution and uncertainties of the TES version 5 retrieval algorithm. In this version (Version 5, joint estimates of H2O, HDO, CH4 and nitrous oxide (N2O are made using radiances from almost the entire spectral region between 1100 cm−1 and 1330 cm−1. The TES retrieval constraints are also modified in order to better use this information. The new H2O estimates show improved vertical resolution in the lower troposphere and boundary layer, while the new HDO/H2O estimates can now profile the HDO/H2O ratio between 925 hPa and 450 hPa in the tropics and during summertime at high latitudes. The new retrievals are now sensitive to methane in the free troposphere between 800 and 150 mb with peak sensitivity near 500 hPa; whereas in previous versions the sensitivity peaked at 200 hPa. However, the upper troposphere methane concentrations are biased high relative to the lower troposphere by approximately 4% on average. This bias is likely related to temperature, calibration, and/or methane spectroscopy errors. This bias can be mitigated by normalizing the CH4 estimate by the ratio of the N2O estimate relative to the N2O prior, under the assumption that the same systematic error affects both the N2O and CH4 estimates. We demonstrate that applying this ratio theoretically reduces the CH4 estimate for non-retrieved parameters that jointly affect both the N2O and CH4 estimates. The relative upper troposphere to lower troposphere bias is approximately 2.8% after this bias

Sensitivity of airborne radio occultation to tropospheric properties over ocean and land

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F. Xie

2018-02-01

Full Text Available Airborne radio occultation (ARO measurements collected during a ferry flight at the end of the PRE-Depression Investigation of Cloud-systems in the Tropics (PREDICT field campaign from the Virgin Islands to Colorado are analyzed. The large contrast in atmospheric conditions along the flight path from the warm and moist Caribbean Sea to the much drier and cooler continental conditions provides a unique opportunity to address the sensitivity of ARO measurements to the tropospheric temperature and moisture changes. This long flight at nearly constant altitude (∼ 13 km provided an optimal configuration for simultaneous high-quality ARO measurements from two high-gain side-looking antennas, as well as one relatively lower gain zenith (top antenna. The omnidirectional top antenna has the advantage of tracking robustly more occulting satellites in all direction as compared to the limited-azimuth tracking of the side-looking antennas. Two well-adapted radio-holographic bending angle retrieval methods, full-spectrum inversion (FSI and phase matching (PM, were compared with the standard geometric-optics (GO retrieval method. Comparison of the ARO retrievals from the top antenna with the near-coincident ECMWF reanalysis-interim (ERA-I profiles shows only a small root-mean-square (RMS refractivity difference of ∼ 0.3 % in the drier upper troposphere from ∼ 5 to ∼ 11.5 km over both land and ocean. Both the FSI and PM methods improve the ARO retrievals in the moist lower troposphere and reduce the negative bias found in the GO retrieval due to atmospheric multipath. In the lowest layer of the troposphere, the ARO refractivity derived using FSI shows a negative bias of about −2 %. The increase of the refractivity bias occurs below 5 km over the ocean and below 3.5 km over land, corresponding to the approximate altitude of large vertical moisture gradients above the ocean and land surface, respectively. In comparisons to

Heated wire humidification circuit attenuates the decrease of core temperature during general anesthesia in patients undergoing arthroscopic hip surgery.

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Park, Sooyong; Yoon, Seok-Hwa; Youn, Ann Misun; Song, Seung Hyun; Hwang, Ja Gyung

2017-12-01

Intraoperative hypothermia is common in patients undergoing general anesthesia during arthroscopic hip surgery. In the present study, we assessed the effect of heating and humidifying the airway with a heated wire humidification circuit (HHC) to attenuate the decrease of core temperature and prevent hypothermia in patients undergoing arthroscopic hip surgery under general anesthesia. Fifty-six patients scheduled for arthroscopic hip surgery were randomly assigned to either a control group using a breathing circuit connected with a heat and moisture exchanger (HME) (n = 28) or an HHC group using a heated wire humidification circuit (n = 28). The decrease in core temperature was measured from anesthetic induction and every 15 minutes thereafter using an esophageal stethoscope. Decrease in core temperature from anesthetic induction to 120 minutes after induction was lower in the HHC group (-0.60 ± 0.27℃) compared to the control group (-0.86 ± 0.29℃) (P = 0.001). However, there was no statistically significant difference in the incidence of intraoperative hypothermia or the incidence of shivering in the postanesthetic care unit. The use of HHC may be considered as a method to attenuate intraoperative decrease in core temperature during arthroscopic hip surgery performed under general anesthesia and exceeding 2 hours in duration.

Tropospheric chemistry over the lower Great Plains of the United States. 2. Trace gas profiles and distributions

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Luke, Winston T.; Dickerson, Russell R.; Ryan, William F.; Pickering, Kenneth E.; Nunnermacker, Linda J.

1992-12-01

Convective clouds and thunderstorms redistribute air pollutants vertically, and by altering the chemistry and radiative balance of the upper troposphere, these local actions can have global consequences. To study these effects, measurements of trace gases ozone, O3, carbon monoxide, CO, and odd nitrogen were made aboard the NCAR Sabreliner on 18 flights over the southern Great Plains during June 1985. To demonstrate chemical changes induced by vertical motions in the atmosphere and to facilitate comparison with computer model calculations, these data were categorized according to synoptic flow patterns. Part 1 of this two-part paper details the alternating pulses of polar and maritime air masses that dominate the vertical mixing in this region. In this paper, trace gas measurements are presented as altitude profiles (0-12 km) with statistical distributions of mixing ratios for each species in each flow pattern. The polar flow regime is characterized by northwesterly winds, subsiding air, and convective stability. Concentrations of CO and total odd nitrogen (NOy) are relatively high in the shallow planetary boundary layer (PBL) but decrease rapidly with altitude. Ozone, on the other hand, is uniformly distributed, suggesting limited photochemical production; in fact, nitric oxide, NO, mixing ratios fell below 10 ppt (parts per 1012 by volume) in the midtroposphere. The maritime regime is characterized by southerly surface winds, convective instability, and a deep PBL; uniformly high concentrations of trace gases were found up to 4 km on one flight. Severe storms occur in maritime flow, especially when capped by a dry layer, and they transport large amounts of CO, O3, and NOy into the upper troposphere. Median NO levels at high altitude exceeded 300 ppt. Lightning produces spikes of NO (but not CO) with mixing ratios sometimes exceeding 1000 ppt. This flow pattern tends to leave the midtroposphere relatively clean with concentrations of trace gases similar to those

ATom observations of new particle formation in the tropical upper troposphere. The role of convection and nucleation mechanisms

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Kupc, A.; Williamson, C.; Hodshire, A. L.; Pierce, J. R.; Ray, E. A.; Froyd, K. D.; Richardson, M.; Weinzierl, B.; Dollner, M.; Erdesz, F.; Bui, T. V.; Diskin, G. S.; Brock, C. A.

2017-12-01

Measurements of size distributions during the Atmospheric Tomography Mission (ATom) reveal high number concentrations (>>1000 cm-3) of nucleation mode particles at high altitudes in the tropics and subtropics under low condensation sink conditions and are associated with upwelling in convective clouds. The broad spatial extent of these newly formed particles shows that the upper free troposphere (FT) of the tropics and subtropics is a globally significant source. In this study, we investigate the link between convection and new particle formation (NPF) by exploring the processes that govern NPF and growth in the tropical and subtropical FT of the Pacific and Atlantic Oceans. We use measurements of the size distributions made with a suite of fast-response instruments on board of a NASA DC-8 aircraft during ATom mission. ATom maps the remote atmosphere over the Pacific and Atlantic basins ( 80 °N and 65 °S) in continuous ascents and descents (0.2 and 13 km), providing the latitudinal and vertical information on the greenhouse gases, reactive and tracer species and aerosol properties and their seasonal variability. We couple measurements of size distributions between 0.003 and 4.8 µm and potential aerosol precursor vapors measured on ATom (August 2016 and February 2017) with calculated air mass back trajectories and the TwO-Moment Aerosol Sectional (TOMAS) box model. The back trajectories identify air masses potentially influenced by recent convection. We then use TOMAS to model particle nucleation, condensation and coagulation along that trajectory to investigate the link between convection and NPF. Through TOMAS, we explore the influence of different nucleation mechanisms (such as binary, ternary or the one with organics) and gas-phase aerosol precursors (such as sulfur dioxide) on observed particle size distributions. We discuss similarities and differences in NPF over the Pacific and Atlantic Oceans and their relationship to convection, examine particle

Impact of selected troposphere models on Precise Point Positioning convergence

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Kalita, Jakub; Rzepecka, Zofia

2016-04-01

The Precise Point Positioning (PPP) absolute method is currently intensively investigated in order to reach fast convergence time. Among various sources that influence the convergence of the PPP, the tropospheric delay is one of the most important. Numerous models of tropospheric delay are developed and applied to PPP processing. However, with rare exceptions, the quality of those models does not allow fixing the zenith path delay tropospheric parameter, leaving difference between nominal and final value to the estimation process. Here we present comparison of several PPP result sets, each of which based on different troposphere model. The respective nominal values are adopted from models: VMF1, GPT2w, MOPS and ZERO-WET. The PPP solution admitted as reference is based on the final troposphere product from the International GNSS Service (IGS). The VMF1 mapping function was used for all processing variants in order to provide capability to compare impact of applied nominal values. The worst case initiates zenith wet delay with zero value (ZERO-WET). Impact from all possible models for tropospheric nominal values should fit inside both IGS and ZERO-WET border variants. The analysis is based on data from seven IGS stations located in mid-latitude European region from year 2014. For the purpose of this study several days with the most active troposphere were selected for each of the station. All the PPP solutions were determined using gLAB open-source software, with the Kalman filter implemented independently by the authors of this work. The processing was performed on 1 hour slices of observation data. In addition to the analysis of the output processing files, the presented study contains detailed analysis of the tropospheric conditions for the selected data. The overall results show that for the height component the VMF1 model outperforms GPT2w and MOPS by 35-40% and ZERO-WET variant by 150%. In most of the cases all solutions converge to the same values during first

Applying Kalman filtering to investigate tropospheric effects in VLBI

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Soja, Benedikt; Nilsson, Tobias; Karbon, Maria; Heinkelmann, Robert; Liu, Li; Lu, Cuixian; Andres Mora-Diaz, Julian; Raposo-Pulido, Virginia; Xu, Minghui; Schuh, Harald

2014-05-01

Very Long Baseline Interferometry (VLBI) currently provides results, e.g., estimates of the tropospheric delays, with a delay of more than two weeks. In the future, with the coming VLBI2010 Global Observing System (VGOS) and increased usage of electronic data transfer, it is planned that the time between observations and results is decreased. This may, for instance, allow the integration of VLBI-derived tropospheric delays into numerical weather prediction models. Therefore, future VLBI analysis software packages need to be able to process the observational data autonomously in near real-time. For this purpose, we have extended the Vienna VLBI Software (VieVS) by a Kalman filter module. This presentation describes the filter and discusses its application for tropospheric studies. Instead of estimating zenith wet delays as piece-wise linear functions in a least-squares adjustment, the Kalman filter allows for more sophisticated stochastic modeling. We start with a random walk process to model the time-dependent behavior of the zenith wet delays. Other possible approaches include the stochastic model described by turbulence theory, e.g. the model by Treuhaft and Lanyi (1987). Different variance-covariance matrices of the prediction error, depending on the time of the year and the geographic latitude, have been tested. In winter and closer to the poles, lower variances and covariances are appropriate. The horizontal variations in tropospheric delays have been investigated by comparing three different strategies: assumption of a horizontally stratified troposphere, using north and south gradients modeled, e.g., as Gauss-Markov processes, and applying a turbulence model assuming correlations between observations in different azimuths. By conducting Monte-Carlo simulations of current standard VLBI networks and of future VGOS networks, the different tropospheric modeling strategies are investigated. For this purpose, we use the simulator module of VieVS which takes into

Retrieval of tropospheric carbon monoxide for the MOPITT experiment

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Pan, Liwen; Gille, John C.; Edwards, David P.; Bailey, Paul L.; Rodgers, Clive D.

1998-12-01

A retrieval method for deriving the tropospheric carbon monoxide (CO) profile and column amount under clear sky conditions has been developed for the Measurements of Pollution In The Troposphere (MOPITT) instrument, scheduled for launch in 1998 onboard the EOS-AM1 satellite. This paper presents a description of the method along with analyses of retrieval information content. These analyses characterize the forward measurement sensitivity, the contribution of a priori information, and the retrieval vertical resolution. Ensembles of tropospheric CO profiles were compiled both from aircraft in situ measurements and from chemical model results and were used in retrieval experiments to characterize the method and to study the sensitivity to different parameters. Linear error analyses were carried out in parallel with the ensemble experiments. Results of these experiments and analyses indicate that MOPITT CO column measurements will have better than 10% precision, and CO profile measurement will have approximately three pieces of independent information that will resolve 3-5 tropospheric layers to approximately 10% precision. These analyses are important for understanding MOPITT data, both for application of data in tropospheric chemistry studies and for comparison with in situ measurements.

Measurements of upper atmosphere water vapor made in situ with a new moisture sensor

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Chleck, D.

1979-01-01

A new thin-film aluminum oxide sensor, Aquamax II, has been developed for the measurement of stratospheric and upper tropospheric water vapor levels. The sensor is briefly described with attention given to its calibration and performance. Data obtained from six balloon flights are presented; almost all the results show a constant water vapor mixing ratio, in agreement with other data from midlatitude regions.

Tropospheric Emissions: Monitoring of Pollution (TEMPO)

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Zoogman, P.; Liu, X.; Suleiman, R. M.; Pennington, W. F.; Flittner, D. E.; Al-Saadi, J. A.; Hilton, B. B.; Nicks, D. K.; Newchurch, M. J.; Carr, J. L.;

Transport of Formaldehyde to the Upper Troposphere In Deep Convective Storms During the 2012 DC3 Study

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Fried, A.; Weibring, P.; Richter, D.; Walega, J.; Olson, J. R.; Crawford, J. H.; Barth, M. C.; Apel, E. C.; Hornbrook, R. S.; Bela, M. M.; Toon, O. B.; Blake, D. R.; Blake, N. J.; Luo, Z. J.

2014-12-01

The Deep Convective Clouds and Chemistry (DC3) campaign in the summer of 2012 provided an opportunity to study the impacts of deep convection on reactive and soluble precursors of ozone and HOx radicals, including CH2O, in the upper troposphere and lower stratosphere (UTLS) over North America. Formaldehyde measurements were acquired in the inflow and outflow of numerous storms on the NASA DC-8 and NSF/NCAR GV-aircraft employing fast, sensitive, and accurate difference frequency generation infrared absorption spectrometers. Since our Fall 2013 AGU Meeting poster, we have developed an improved methodology based upon 3 independent approaches, to determine the amount of CH2O that is scavenged by deep convective storms. The first approach is based upon WRF-Chem model simulations, which provides greater confidence in the determination of CH2O scavenging efficiencies and allows the estimation of CH2O ice retention factors.The second approach is a modified mixing model employing 4 non-reactive passive tracers (n,i-butane, n,i-pentane) to estimate altitude-dependent lateral entrainment rates. This information is coupled with time-dependent measurements in the outflow of various storms, which when extrapolated to time zero in the storm core, results in estimates of CH2O scavenging efficiencies. This analysis includes estimates of photochemically produced CH2O in the storm core. A third approach is based upon CH2O/n-butane ratio comparisons in both the storm inflow and outflow. Results from various storms over Oklahoma, Colorado, and Alabama will be presented. However, the analysis will primarily focus on the May 29, 2012 supercell storm in Oklahoma. During this storm, the 4 passive tracers produced a very consistent lateral entrainment rate of 0.083 ± 0.008 km-1, a value that broadly agrees with entrainment rates determined previously from analyzing moist static energy profiles (Luo et al., Geophys. Res. Lett., 2010). For this storm, the 3-independent approaches give CH2O

Transport pathways of CO in the African upper troposphere during the monsoon season: a study based upon the assimilation of spaceborne observations

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B. Barret

2008-06-01

Full Text Available The transport pathways of carbon monoxide (CO in the African Upper Troposphere (UT during the West African Monsoon (WAM is investigated through the assimilation of CO observations by the Aura Microwave Limb Sounder (MLS in the MOCAGE Chemistry Transport Model (CTM. The assimilation setup, based on a 3-D First Guess at Assimilation Time (3-D-FGAT variational method is described. Comparisons between the assimilated CO fields and in situ airborne observations from the MOZAIC program between Europe and both Southern Africa and Southeast Asia show an overall good agreement around the lowermost pressure level sampled by MLS (~215 hPa. The 4-D assimilated fields averaged over the month of July 2006 have been used to determine the main dynamical processes responsible for the transport of CO in the African UT. The studied period corresponds to the second AMMA (African Monsoon Multidisciplinary Analyses aircraft campaign. At 220 hPa, the CO distribution is characterized by a latitudinal maximum around 5° N mostly driven by convective uplift of air masses impacted by biomass burning from Southern Africa, uplifted within the WAM region and vented predominantly southward by the upper branch of the winter hemisphere Hadley cell. Above 150 hPa, the African CO distribution is characterized by a broad maximum over northern Africa. This maximum is mostly controlled by the large scale UT circulation driven by the Asian Summer Monsoon (ASM and characterized by the Asian Monsoon Anticyclone (AMA centered at 30° N and the Tropical Easterly Jet (TEJ on the southern flank of the anticyclone. Asian pollution uplifted to the UT over large region of Southeast Asia is trapped within the AMA and transported by the anticyclonic circulation over Northeast Africa. South of the AMA, the TEJ is responsible for the tranport of CO-enriched air masses from India and Southeast Asia over Africa. Using the high time resolution provided by the 4-D assimilated fields, we give evidence

The Potential of Tropospheric Gradients for Regional Precipitation Prediction

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Boisits, Janina; Möller, Gregor; Wittmann, Christoph; Weber, Robert

2017-04-01

Changes of temperature and humidity in the neutral atmosphere cause variations in tropospheric path delays and tropospheric gradients. By estimating zenith wet delays (ZWD) and gradients using a GNSS reference station network the obtained time series provide information about spatial and temporal variations of water vapour in the atmosphere. Thus, GNSS-based tropospheric parameters can contribute to the forecast of regional precipitation events. In a recently finalized master thesis at TU Wien the potential of tropospheric gradients for weather prediction was investigated. Therefore, ZWD and gradient time series at selected GNSS reference stations were compared to precipitation data over a period of six months (April to September 2014). The selected GNSS stations form two test areas within Austria. All required meteorological data was provided by the Central Institution for Meteorology and Geodynamics (ZAMG). Two characteristics in ZWD and gradient time series can be anticipated in case of an approaching weather front. First, an induced asymmetry in tropospheric delays results in both, an increased magnitude of the gradient and in gradients pointing towards the weather front. Second, an increase in ZWD reflects the increased water vapour concentration right before a precipitation event. To investigate these characteristics exemplary test events were processed. On the one hand, the sequence of the anticipated increase in ZWD at each GNSS station obtained by cross correlation of the time series indicates the direction of the approaching weather front. On the other hand, the corresponding peak in gradient time series allows the deduction of the direction of movement as well. To verify the results precipitation data from ZAMG was used. It can be deduced, that tropospheric gradients show high potential for predicting precipitation events. While ZWD time series rather indicate the orientation of the air mass boundary, gradients rather indicate the direction of movement

Automatic humidification system to support the assessment of food drying processes

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Ortiz Hernández, B. D.; Carreño Olejua, A. R.; Castellanos Olarte, J. M.

2016-07-01

This work shows the main features of an automatic humidification system to provide drying air that match environmental conditions of different climate zones. This conditioned air is then used to assess the drying process of different agro-industrial products at the Automation and Control for Agro-industrial Processes Laboratory of the Pontifical Bolivarian University of Bucaramanga, Colombia. The automatic system allows creating and improving control strategies to supply drying air under specified conditions of temperature and humidity. The development of automatic routines to control and acquire real time data was made possible by the use of robust control systems and suitable instrumentation. The signals are read and directed to a controller memory where they are scaled and transferred to a memory unit. Using the IP address is possible to access data to perform supervision tasks. One important characteristic of this automatic system is the Dynamic Data Exchange Server (DDE) to allow direct communication between the control unit and the computer used to build experimental curves.

Multi-objective Optimization of a Solar Humidification Dehumidification Desalination Unit

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Rafigh, M.; Mirzaeian, M.; Najafi, B.; Rinaldi, F.; Marchesi, R.

2017-11-01

In the present paper, a humidification-dehumidification desalination unit integrated with solar system is considered. In the first step mathematical model of the whole plant is represented. Next, taking into account the logical constraints, the performance of the system is optimized. On one hand it is desired to have higher energetic efficiency, while on the other hand, higher efficiency results in an increment in the required area for each subsystem which consequently leads to an increase in the total cost of the plant. In the present work, the optimum solution is achieved when the specific energy of the solar heater and also the areas of humidifier and dehumidifier are minimized. Due to the fact that considered objective functions are in conflict, conventional optimization methods are not applicable. Hence, multi objective optimization using genetic algorithm which is an efficient tool for dealing with problems with conflicting objectives has been utilized and a set of optimal solutions called Pareto front each of which is a tradeoff between the mentioned objectives is generated.

Oxygen With Cold Bubble Humidification Is No Better Than Dry Oxygen in Preventing Mucus Dehydration, Decreased Mucociliary Clearance, and Decline in Pulmonary Function.

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Franchini, Michelle Lisidati; Athanazio, Rodrigo; Amato-Lourenço, Luis Fernando; Carreirão-Neto, Waldir; Saldiva, Paulo Hilario Nascimento; Lorenzi-Filho, Geraldo; Rubin, Bruce K; Nakagawa, Naomi Kondo

2016-08-01

Little is known about the effects of long-term nasal low-flow oxygen (NLFO) on mucus and symptoms and how this variable is affected by dry or cold humidified gas. The aim of this study was to investigate the effects of dry-NLFO and cold bubble humidified-NLFO on nasal mucociliary clearance (MCC), mucus properties, inflammation, and symptoms in subjects with chronic hypoxemia requiring long-term domiciliary oxygen therapy. Eighteen subjects (mean age, 68 years; 7 male; 66% with COPD) initiating NLFO were randomized to receive dry-NLFO (n = 10) or humidified-NLFO (n = 8). Subjects were assessed at baseline, 12 h, 7 days, 30 days, 12 months, and 24 months by measuring nasal MCC using the saccharin transit test, mucus contact angle (surface tension), inflammation (cells and cytokine concentration in nasal lavage), and symptoms according to the Sino-Nasal Outcome Test-20. Nasal MCC decreased significantly (40% longer saccharin transit times) and similarly in both groups over the study period. There was a significant association between impaired nasal MCC and decline in lung function. Nasal lavage revealed an increased proportion of macrophages, interleukin-8, and epidermal growth factor concentrations with decreased interleukin-10 during the study. No changes in the proportion of ciliated cells or contact angle were observed. Coughing and sleep symptoms decreased similarly in both groups. There were no outcome differences comparing dry vs cold bubble humidified NLFO. In subjects receiving chronic NLFO, cold bubble humidification does not adequately humidify inspired oxygen to prevent deterioration of MCC, mucus hydration, and pulmonary function. The unheated bubble humidification performed no better than no humidification. ClinicalTrials.gov; No.: NCT02515786; URL: www.clinicaltrials.gov. Copyright © 2016 American College of Chest Physicians. Published by Elsevier Inc. All rights reserved.

Heated insufflation with or without humidification for laparoscopic abdominal surgery.

Science.gov (United States)

Birch, Daniel W; Dang, Jerry T; Switzer, Noah J; Manouchehri, Namdar; Shi, Xinzhe; Hadi, Ghassan; Karmali, Shahzeer

2016-10-19

Intraoperative hypothermia during both open and laparoscopic abdominal surgery may be associated with adverse events. For laparoscopic abdominal surgery, the use of heated insufflation systems for establishing pneumoperitoneum has been described to prevent hypothermia. Humidification of the insufflated gas is also possible. Past studies on heated insufflation have shown inconclusive results with regards to maintenance of core temperature and reduction of postoperative pain and recovery times. To determine the effect of heated gas insufflation compared to cold gas insufflation on maintaining intraoperative normothermia as well as patient outcomes following laparoscopic abdominal surgery. We searched Cochrane Colorectal Cancer Specialised Register (September 2016), the Cochrane Central Register of Controlled Trials (CENTRAL; The Cochrane Library 2016, Issue 8), Ovid MEDLINE (1950 to September 2016), Ovid Embase (1974 to September 2016), International Pharmaceutical Abstracts (IPA) (September 2016), Web of Science (1985 to September 2016), Scopus, www.clinicaltrials.gov and the National Research Register (1956 to September 2016). We also searched grey literature and cross references. Searches were limited to human studies without language restriction. Only randomised controlled trials comparing heated (with or without humidification) with cold gas insufflation in adult and paediatric populations undergoing laparoscopic abdominal procedures were included. We assessed study quality in regards to relevance, design, sequence generation, allocation concealment, blinding, possibility of incomplete data and selective reporting. Two review authors independently selected studies for the review, with any disagreement resolved in consensus with a third co-author. Two review authors independently performed screening of eligible studies, data extraction and methodological quality assessment of the trials. We classified a study as low-risk of bias if all of the first six main

Evaluation of the tropospheric flows to a major Southern Hemisphere stratospheric warming event using NCEP/NCAR Reanalysis data with a PSU/NCAR nudging MM5V3 model

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Wang, K.

2008-04-01

Previous studies of the exceptional 2002 Southern Hemisphere (SH) stratospheric warming event lead to some uncertainty, namely the question of whether excessive heat fluxes in the upper troposphere and lower stratosphere are a symptom or cause of the 2002 SH warming event. In this work, we use a hemispheric version of the MM5 model with nudging capability and we devised a novel approach to separately test the significance of the stratosphere and troposphere for this year. We paired the flow conditions from 2002 in the stratosphere and troposphere, respectively, against the conditions in 1998 (a year with displaced polar vortex) and in 1948 (a year with strong polar vortex that coincided with the geographical South Pole). Our experiments show that the flow conditions from below determine the stratospheric flow features over the polar region. Regardless of the initial stratospheric conditions in 1998 or 1948, when we simulated these past stratospheres with the troposphere/lower stratosphere conditions constrained to 2002 levels, the simulated middle stratospheres resemble those observed in 2002 stratosphere over the polar region. On the other hand, when the 2002 stratosphere was integrated with the troposphere/lower stratosphere conductions constrained to 1948 and 1998, respectively, the simulated middle stratospheric conditions over the polar region shift toward those of 1948 and 1998. Thus, our experiments further support the wave-forcing theory as the cause of the 2002 SH warming event.

Influence of the North Atlantic Oscillation on European tropospheric composition: an observational and modelling study

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Pope, R.; Chipperfield, M.

2017-12-01

The North Atlantic Oscillation (NAO) has a strong influence on winter-time North Atlantic and European circulation patterns. Under the positive phase of the NAO (NAO+), intensification of the climatological Icelandic low and Azores high pressure systems results in strong westerly flow across the Atlantic into Europe. Under the NAO negative phase (NAO-), there is a weakening of this meridional pressure gradient resulting in a southerly shift in the westerlies flow towards the sub-tropical Atlantic. Therefore, NAO+ and NAO- introduce unstable stormy and drier stable conditions into Europe, respectively. Under NAO+ conditions, the strong westerlies tend to enhance transport of European pollution (e.g. nitrogen oxides) away from anthropogenic source regions. While during NAO-, the more stable conditions lead to a build up of pollutants. However, secondary pollutants (i.e. tropospheric ozone) show the opposite signal where NAO+, while transporting primary pollutants away, introduces Atlantic ozone enriched air into Europe. Here ozone can form downwind of pollution from continental North America and be transported into Europe via the westerly flow. Under NAO-, this westerly ozone transport is reduced yielding lower European ozone concentrations also depleted further by ozone loss through the reaction with NOx, which has accumulated over the continent. Peroxyacetyl nitrate (PAN), observed in the upper troposphere - lower stratosphere (UTLS) by satellite, peaks over Iceland/Southern Greenland in NAO-, between 200-100 hPa, consistent with trapping by an anticyclone at this altitude. During NAO+, PAN is enhanced over the sub-tropical Atlantic and Arctic. Model simulations show that enhanced PAN over Iceland/Southern Greenland in NAO- is associated with vertical transport from the troposphere into the UTLS, while peak Arctic PAN in NAO+ is its accumulation given the strong northerly meridional transport in the UTLS. UTLS ozone spatial anomalies, relative to the winter

Photochemistry of the African troposphere: Influence of biomass-burning emissions

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Marufu, L.; Dentener, F.; Lelieveld, J.; Andreae, M. O.; Helas, G.

2000-06-01

The relative importance of biomass-burning (pyrogenic) emissions from savannas, deforestation, agricultural waste burning, and biofuel consumption to tropospheric ozone abundance over Africa has been estimated for the year 1993, on the basis of global model calculations. We also calculated the importance of this emission source to tropospheric ozone in other regions of the world and compared it to different sources on the African regional and global scales. The estimated annual average total tropospheric ozone abundance over Africa for the reference year is 26 Tg. Pyrogenic, industrial, biogenic, and lightning emissions account for 16, 19, 12, and 27%, respectively, while stratospheric ozone input accounts for 26%. In the planetary boundary layer over Africa, the contribution by biomass burning is ˜24%. A large fraction of the African biomass-burning-related ozone is transported away from the continent. On a global scale, biomass burning contributes ˜9% to tropospheric ozone. Our model calculations suggest that Africa is the single most important region for biomass-burning-related tropospheric ozone, accounting for ˜35% of the global annual pyrogenic ozone enhancement of 29 Tg in 1993.

(abstract) Tropospheric Calibration for the Mars Observer Gravity Wave Experiment

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Walter, Steven J.; Armstrong, John

1994-01-01

In spring 1993, microwave radiometer-based tropospheric calibration was provided for the Mars Observer gravitational wave search. The Doppler shifted X-band radio signals propagating between Earth and the Mars Observer satellite were precisely measured to determine path length variations that might signal passage of gravitational waves. Experimental sensitivity was restricted by competing sources of variability in signal transit time. Principally, fluctuations in the solar wind and ionospheric plasma density combined with fluctions in tropospheric refractivity determined the detection limit. Troposphere-induced path delay fluctions are dominated by refractive changes caused by water vapor inhomogeneities blowing through the signal path. Since passive microwave remote sensing techniques are able to determine atmospheric propagation delays, radiometer-based tropospheric calibration was provided at the Deep Space Network Uranus tracking site (DSS-15). Two microwave water vapor radiometers (WVRs), a microwave temperature profiler (MTP), and a ground based meterological station were deployed to determine line-of-sight vapor content and vertical temperature profile concurrently with Mars Observer tracking measurements. This calibration system provided the capability to correct Mars Observer Doppler data for troposphere-induced path variations. We present preliminary analysis of the Doppler and WVR data sets illustrating the utility of WVRs to calibrate Doppler data. This takes an important step toward realizing the ambitious system required to support future Ka-band Cassini satellite gravity wave tropospheric calibration system.

The Tropospheric Ozone Assessment Report (TOAR): A community-wide effort to quantify tropospheric ozone in a rapidly changing world

Science.gov (United States)

Cooper, O. R.; Schultz, M.; Paoletti, E.; Galbally, I. E.; Naja, M. K.; Tarasick, D. W.; Evans, M. J.; Thompson, A. M.

2017-12-01

Tropospheric ozone is a greenhouse gas and pollutant detrimental to human health and crop and ecosystem productivity. Since 1990 a large portion of the anthropogenic emissions that react in the atmosphere to produce ozone has shifted from North America and Europe to Asia. This rapid shift, coupled with limited ozone monitoring in developing nations, left scientists unable to answer the most basic questions: Which regions of the world have the greatest human and plant exposure to ozone pollution? Is ozone continuing to decline in nations with strong emissions controls? To what extent is ozone increasing in the developing world? How can the atmospheric sciences community facilitate access to the ozone metrics necessary for quantifying ozone's impact on human health and crop/ecosystem productivity? To answer these questions the International Global Atmospheric Chemistry Project (IGAC) initiated the Tropospheric Ozone Assessment Report (TOAR). With over 220 member scientists and air quality specialists from 36 nations, TOAR's mission is to provide the research community with an up-to-date scientific assessment of tropospheric ozone's global distribution and trends from the surface to the tropopause. TOAR has also built the world's largest database of surface ozone observations and generated ozone exposure and dose metrics at thousands of measurement sites around the world, freely accessible for research on the global-scale impact of ozone on climate, human health and crop/ecosystem productivity. Plots of these metrics show the regions of the world with the greatest ozone exposure for humans and crops/ecosystems, at least in areas where observations are available. The results also highlight regions where air quality is improving and where it has degraded. TOAR has also conducted the first intercomparison of tropospheric column ozone from ozonesondes and multiple satellite instruments, which provide similar estimates of the present-day tropospheric ozone burden.

Tropospheric Emission Spectrometer (TES) Data

Data.gov (United States)

National Aeronautics and Space Administration — TES focuses on the troposphere, the layer of atmosphere that stretches from the ground to the altitude at which airplanes fly. With very high spectral resolution,...

Airborne measurement of peroxy radicals in the lower troposphere

Science.gov (United States)

Andrés Hernández, Maria Dolores; Horstjann, Markus; Kartal, Deniz; Krebsbach, Marc; Linke, Christian; Lichtenstern, Michael; Andrey, Javier; Burrows, John P.

2013-04-01

The importance of peroxy radicals in the tropospheric chemistry is well recognized in the scientific literature. Hydroxy- and organic peroxy radicals (HO2 and RO2, R being an organic chain) are key intermediates in the OH radical initiated oxidation of CO and SO2, of volatile organic compounds (VOC), in the ozonolysis of alkenes and photo-oxidation of carbonyl species. Peroxy radicals are responsible for the ozone production in the troposphere, the formation of peroxides and other oxidants. Although radical chemistry in the troposphere has been subject of intensive research in the past three decades, it is still very few known about the vertical distribution of peroxy radicals. Airborne observations are scarce in spite of their particular importance to improve the understanding of the tropospheric chemistry and the oxidising capacity of the atmosphere at different altitudes. In situ trace gas measurements were carried out in summer 2010 on board of the INTA (Instituto Nacional de Técnicas Aeroespaciales) C212 aircraft over Spain in the frame of the EUFAR project VERDRILLT (VERtical Distribution of Radicals In the Lower Layers of the Troposphere), and in cooperation with the DLR (Deutsches Zentrum für Luft- und Raumfahrt), the University of Wuppertal, the CEAM (Centro de Estudios Ambientales del Mediterráneo) and the UPV-EHU University in Bilbao. VERDRILLT aimed at getting a deeper understanding of the vertical distribution of peroxy radicals in the lower layers of the troposphere. Measurements were taken over urban areas and extensions of different vegetation under meteorological conditions favouring active photochemistry and convection from the ground into close atmospheric layers. Results and main findings will be presented and discussed.

Climate change projections and stratosphere-troposphere interaction

Energy Technology Data Exchange (ETDEWEB)

Scaife, Adam A.; Fereday, David R.; Butchart, Neal; Hardiman, Steven C. [Met Office Hadley Centre, Exeter (United Kingdom); Spangehl, Thomas; Cubasch, Ulrich; Langematz, Ulrike [Freie Universitaet Berlin, Berlin (Germany); Akiyoshi, Hideharu [National Institute for Environmental Studies, Tsukuba (Japan); Bekki, Slimane [LATMOS-IPSL, UVSQ, UPMC, CNRS/INSU, Paris (France); Braesicke, Peter [University of Cambridge, Cambridge (United Kingdom); Chipperfield, Martyn P. [University of Leeds, School of Earth and Environment, Leeds (United Kingdom); Gettelman, Andrew [National Center for Atmospheric Research, Boulder, CO (United States); Michou, Martine [GAME/CNRM (Meteo France, CNRS), Toulouse (France); Rozanov, Eugene [PMOD/WRC and ETHZ, Davos (Switzerland); Shepherd, Theodore G. [University of Toronto, Toronto, ON (Canada)

2012-05-15

Climate change is expected to increase winter rainfall and flooding in many extratropical regions as evaporation and precipitation rates increase, storms become more intense and storm tracks move polewards. Here, we show how changes in stratospheric circulation could play a significant role in future climate change in the extratropics through an additional shift in the tropospheric circulation. This shift in the circulation alters climate change in regional winter rainfall by an amount large enough to significantly alter regional climate change projections. The changes are consistent with changes in stratospheric winds inducing a change in the baroclinic eddy growth rate across the depth of the troposphere. A change in mean wind structure and an equatorward shift of the tropospheric storm tracks relative to models with poor stratospheric resolution allows coupling with surface climate. Using the Atlantic storm track as an example, we show how this can double the predicted increase in extreme winter rainfall over Western and Central Europe compared to other current climate projections. (orig.)

Effect of the hydrophilic and hydrophobic characteristics of the gas diffusion medium on polymer electrolyte fuel cell performance under non-humidification condition

International Nuclear Information System (INIS)

Park, Heesung

2014-01-01

Highlights: • GDM played significant role in the PEFC performance under dry condition. • Hydrophobicity of GDM affect the water condensation at the surface. • Optimum water saturation in the porous layer was between 0.1 and 0.3. - Abstract: Water is a significant component of polymer electrolyte fuel cells, affecting the proton conductivity in the membrane electrolyte. Therefore, polymer electrolyte fuel cells are generally operated with a humidifier to maintain a high relative humidity of the supplied gases; however, the humidifier contributes additional weight and cost. Although many studies have attempted to develop polymer electrolyte fuel cells without a humidifier, the studies have been mainly focused on the self-humidified membrane electrolyte and catalyst layer. In this paper, the author investigates the effect of polytetrafluoroethylene coated gas diffusion medium on the water content in the membrane electrolyte. The water condensation on the surfaces of the gas diffusion medium is visualised when the polymer electrolyte fuel cell is operated under non-humidification conditions. Numerical simulation suggests that the optimum water saturation is between 0.1 and 0.3 at the gas diffusion medium to hydrate the membrane electrolyte sufficiently without significantly blocking the diffused species under non-humidification conditions

Impacts of stratospheric sulfate geoengineering on tropospheric ozone

Directory of Open Access Journals (Sweden)

L. Xia

2017-10-01

Full Text Available A range of solar radiation management (SRM techniques has been proposed to counter anthropogenic climate change. Here, we examine the potential effects of stratospheric sulfate aerosols and solar insolation reduction on tropospheric ozone and ozone at Earth's surface. Ozone is a key air pollutant, which can produce respiratory diseases and crop damage. Using a version of the Community Earth System Model from the National Center for Atmospheric Research that includes comprehensive tropospheric and stratospheric chemistry, we model both stratospheric sulfur injection and solar irradiance reduction schemes, with the aim of achieving equal levels of surface cooling relative to the Representative Concentration Pathway 6.0 scenario. This allows us to compare the impacts of sulfate aerosols and solar dimming on atmospheric ozone concentrations. Despite nearly identical global mean surface temperatures for the two SRM approaches, solar insolation reduction increases global average surface ozone concentrations, while sulfate injection decreases it. A fundamental difference between the two geoengineering schemes is the importance of heterogeneous reactions in the photochemical ozone balance with larger stratospheric sulfate abundance, resulting in increased ozone depletion in mid- and high latitudes. This reduces the net transport of stratospheric ozone into the troposphere and thus is a key driver of the overall decrease in surface ozone. At the same time, the change in stratospheric ozone alters the tropospheric photochemical environment due to enhanced ultraviolet radiation. A shared factor among both SRM scenarios is decreased chemical ozone loss due to reduced tropospheric humidity. Under insolation reduction, this is the dominant factor giving rise to the global surface ozone increase. Regionally, both surface ozone increases and decreases are found for both scenarios; that is, SRM would affect regions of the world differently in terms of air

Impacts of stratospheric sulfate geoengineering on tropospheric ozone

Science.gov (United States)

Xia, Lili; Nowack, Peer J.; Tilmes, Simone; Robock, Alan

2017-10-01

A range of solar radiation management (SRM) techniques has been proposed to counter anthropogenic climate change. Here, we examine the potential effects of stratospheric sulfate aerosols and solar insolation reduction on tropospheric ozone and ozone at Earth's surface. Ozone is a key air pollutant, which can produce respiratory diseases and crop damage. Using a version of the Community Earth System Model from the National Center for Atmospheric Research that includes comprehensive tropospheric and stratospheric chemistry, we model both stratospheric sulfur injection and solar irradiance reduction schemes, with the aim of achieving equal levels of surface cooling relative to the Representative Concentration Pathway 6.0 scenario. This allows us to compare the impacts of sulfate aerosols and solar dimming on atmospheric ozone concentrations. Despite nearly identical global mean surface temperatures for the two SRM approaches, solar insolation reduction increases global average surface ozone concentrations, while sulfate injection decreases it. A fundamental difference between the two geoengineering schemes is the importance of heterogeneous reactions in the photochemical ozone balance with larger stratospheric sulfate abundance, resulting in increased ozone depletion in mid- and high latitudes. This reduces the net transport of stratospheric ozone into the troposphere and thus is a key driver of the overall decrease in surface ozone. At the same time, the change in stratospheric ozone alters the tropospheric photochemical environment due to enhanced ultraviolet radiation. A shared factor among both SRM scenarios is decreased chemical ozone loss due to reduced tropospheric humidity. Under insolation reduction, this is the dominant factor giving rise to the global surface ozone increase. Regionally, both surface ozone increases and decreases are found for both scenarios; that is, SRM would affect regions of the world differently in terms of air pollution. In conclusion

Diurnal variation of tropospheric temperature at a tropical station

Directory of Open Access Journals (Sweden)

K. Revathy

2001-08-01

Full Text Available The vertical velocity in the troposphere-lower stratosphere region measured using MST radar has been utilized to evaluate the temperature profile in the region. The diurnal variation of the tropospheric temperature on one day in August 1998 at the tropical station Gadanki (13.5° N, 79.2° E has been studied using the MST radar technique. The diurnal variation of the temperature revealed a prominent diurnal variation with the peak in the afternoon hours increasingly delayed in altitude. The tropopause temperature and altitude exhibited a clear diurnal cycle.Key words. Atmospheric composition and structure (pressure, density and temperature; troposphere - composition and chemistry; instruments and technique

Tropospheric ozone trend over Beijing from 2002–2010: ozonesonde measurements and modeling analysis

Directory of Open Access Journals (Sweden)

Y. Wang

2012-09-01

Full Text Available Using a combination of ozonesonde data and numerical simulations of the Chemical Lagrangian Model of the Stratosphere (CLaMS, the trend of tropospheric ozone (O₃ during 2002–2010 over Beijing was investigated. Tropospheric ozone over Beijing shows a winter minimum and a broad summer maximum with a clear positive trend in the maximum summer ozone concentration over the last decade. The observed significant trend of tropospheric column ozone is mainly caused by photochemical production (3.1% yr⁻¹ for a mean level of 52 DU. This trend is close to the significant trend of partial column ozone in the lower troposphere (0–3 km resulting from the enhanced photochemical production during summer (3.0% yr⁻¹ for a mean level of 23 DU. Analysis of the CLaMS simulation shows that transport rather than chemistry drives most of the seasonality of tropospheric ozone. However, dynamical processes alone cannot explain the trend of tropospheric ozone in the observational data. Clearly enhanced ozone values and a negative vertical ozone gradient in the lower troposphere in the observational data emphasize the importance of photochemistry within the troposphere during spring and summer, and suggest that the photochemistry within the troposphere significantly contributes to the tropospheric ozone trend over Beijing during the last decade.

The GCOS Reference Upper-Air Network (GRUAN)

Science.gov (United States)

Vömel, H.; Berger, F. H.; Immler, F. J.; Seidel, D.; Thorne, P.

2009-04-01

While the global upper-air observing network has provided useful observations for operational weather forecasting for decades, its measurements lack the accuracy and long-term continuity needed for understanding climate change. Consequently, the scientific community faces uncertainty on such key issues as the trends of temperature in the upper troposphere and stratosphere or the variability and trends of stratospheric water vapour. To address these shortcomings, and to ensure that future climate records will be more useful than the records to date, the Global Climate Observing System (GCOS) program initiated the GCOS Reference Upper Air Network (GRUAN). GRUAN will be a network of about 30-40 observatories with a representative sampling of geographic regions and surface types. These stations will provide upper-air reference observations of the essential climate variables, i.e. temperature, geopotential, humidity, wind, radiation and cloud properties using specialized radiosondes and complementary remote sensing profiling instrumentation. Long-term stability, quality assurance / quality control, and a detailed assessment of measurement uncertainties will be the key aspects of GRUAN observations. The network will not be globally complete but will serve to constrain and adjust data from more spatially comprehensive global observing systems including satellites and the current radiosonde networks. This paper outlines the scientific rationale for GRUAN, its role in the Global Earth Observation System of Systems, network requirements and likely instrumentation, management structure, current status and future plans.

A Prototype of Tropospheric Delay Correction in L1-SAIF Augmentation

Science.gov (United States)

Takeichi, Noboru; Sakai, Takeyasu; Fukushima, Sounosuke; Ito, Ken

L1-SAIF signal is one of the navigation signals of Quasi-Zenith Satellite System, which provides an augmentation function for mobile users in Japan. This paper presents the detail of the tropospheric delay correction in L1-SAIF augmentation. The tropospheric delay correction information is generated at the ground station using the data collected at GEONET (GPS Earth Observation NETwork) stations. The correction message contains the information of the zenith tropospheric delay (ZTD) values at 105 Tropospheric Grid Points (TGP) in the experiment area. From this message a mobile user can acquire the ZTD value at some neighboring TGPs, and estimate the local ZTD value accurately by using a suitable ZTD model function. Only 3 L1-SAIF messages are necessary to provide all of the tropospheric correction information. Several investigations using the actual data observed at many GEONET stations overall Japan have proved that it is possible to achieve the correction accuracy of 13.2mm (rms).

Tropospheric Ozone Assessment Report: Present-day distribution and trends of tropospheric ozone relevant to climate and global atmospheric chemistry model evaluation

Directory of Open Access Journals (Sweden)

A. Gaudel

2018-05-01

Full Text Available 'The Tropospheric Ozone Assessment Report' (TOAR is an activity of the International Global Atmospheric Chemistry Project. This paper is a component of the report, focusing on the present-day distribution and trends of tropospheric ozone relevant to climate and global atmospheric chemistry model evaluation. Utilizing the TOAR surface ozone database, several figures present the global distribution and trends of daytime average ozone at 2702 non-urban monitoring sites, highlighting the regions and seasons of the world with the greatest ozone levels. Similarly, ozonesonde and commercial aircraft observations reveal ozone’s distribution throughout the depth of the free troposphere. Long-term surface observations are limited in their global spatial coverage, but data from remote locations indicate that ozone in the 21st century is greater than during the 1970s and 1980s. While some remote sites and many sites in the heavily polluted regions of East Asia show ozone increases since 2000, many others show decreases and there is no clear global pattern for surface ozone changes since 2000. Two new satellite products provide detailed views of ozone in the lower troposphere across East Asia and Europe, revealing the full spatial extent of the spring and summer ozone enhancements across eastern China that cannot be assessed from limited surface observations. Sufficient data are now available (ozonesondes, satellite, aircraft across the tropics from South America eastwards to the western Pacific Ocean, to indicate a likely tropospheric column ozone increase since the 1990s. The 2014–2016 mean tropospheric ozone burden (TOB between 60°N–60°S from five satellite products is 300 Tg ± 4%. While this agreement is excellent, the products differ in their quantification of TOB trends and further work is required to reconcile the differences. Satellites can now estimate ozone’s global long-wave radiative effect, but evaluation is difficult due to limited

Tropospheric Halogen Chemistry

Science.gov (United States)

von Glasow, R.; Crutzen, P. J.

2003-12-01

Halogens are very reactive chemicals that are known to play an important role in anthropogenic stratospheric ozone depletion chemistry, first recognized by Molina and Rowland (1974). However, they also affect the chemistry of the troposphere. They are of special interest because they are involved in many reaction cycles that can affect the oxidation power of the atmosphere indirectly by influencing the main oxidants O3 and its photolysis product OH and directly, e.g., by reactions of the Cl radical with hydrocarbons (e.g., CH4).Already by the middle of the nineteenth century, Marchand (1852) reported the presence of bromine and iodine in rain and other natural waters. He also mentions the benefits of iodine in drinking water through the prevention of goitres and cretinism. In a prophetic monograph "Air and Rain: The Beginnings of a Chemical Climatology," Smith (1872) describes measurements of chloride in rain water, which he states to originate partly from the oceans by a process that he compares with the bursting of "soap bubbles" which produces "small vehicles" that transfer small spray droplets of seawater to the air. From deviations of the sulfate-to-chloride ratio in coastal rain compared to seawater, Smith concluded that chemical processes occur once the particles are airborne.For almost a century thereafter, however, atmospheric halogens received little attention. One exception was the work by Cauer (1939), who reported that iodine pollution has been significant in Western and Central Europe due to the inefficient burning of seaweed, causing mean gas phase atmospheric concentrations as high as or greater than 0.5 μg m-3. In his classical textbook Air Chemistry and Radioactivity, Junge (1963) devoted less than three pages to halogen gas phase chemistry, discussing chlorine and iodine. As reviewed by Eriksson (1959a, b), the main atmospheric source of halogens is sea salt, derived from the bursting of bubbles of air which are produced by ocean waves and other

Relationships between lower tropospheric stability, low cloud cover, and water vapor isotopic composition in the subtropical Pacific

Science.gov (United States)

Galewsky, J.

2017-12-01

Understanding the processes that govern the relationships between lower tropospheric stability and low-cloud cover is crucial for improved constraints on low-cloud feedbacks and for improving the parameterizations of low-cloud cover used in climate models. The stable isotopic composition of atmospheric water vapor is a sensitive recorder of the balance of moistening and drying processes that set the humidity of the lower troposphere and may thus provide a useful framework for improving our understanding low-cloud processes. In-situ measurements of water vapor isotopic composition collected at the NOAA Mauna Loa Observatory in Hawaii, along with twice-daily soundings from Hilo and remote sensing of cloud cover, show a clear inverse relationship between the estimated inversion strength (EIS) and the mixing ratios and water vapor δ -values, and a positive relationship between EIS, deuterium excess, and Δ δ D, defined as the difference between an observation and a reference Rayleigh distillation curve. These relationships are consistent with reduced moistening and an enhanced upper-tropospheric contribution above the trade inversion under high EIS conditions and stronger moistening under weaker EIS conditions. The cloud fraction, cloud liquid water path, and cloud-top pressure were all found to be higher under low EIS conditions. Inverse modeling of the isotopic data for the highest and lowest terciles of EIS conditions provide quantitative constraints on the cold-point temperatures and mixing fractions that govern the humidity above the trade inversion. The modeling shows the moistening fraction between moist boundary layer air and dry middle tropospheric air 24±1.5% under low EIS conditions is and 6±1.5% under high EIS conditions. A cold-point (last-saturation) temperature of -30C can match the observations for both low and high EIS conditions. The isotopic composition of the moistening source as derived from the inversion (-114±10‰ ) requires moderate

Real-Time Tropospheric Product Establishment and Accuracy Assessment in China

Science.gov (United States)

Chen, M.; Guo, J.; Wu, J.; Song, W.; Zhang, D.

2018-04-01

Tropospheric delay has always been an important issue in Global Navigation Satellite System (GNSS) processing. Empirical tropospheric delay models are difficult to simulate complex and volatile atmospheric environments, resulting in poor accuracy of the empirical model and difficulty in meeting precise positioning demand. In recent years, some scholars proposed to establish real-time tropospheric product by using real-time or near-real-time GNSS observations in a small region, and achieved some good results. This paper uses real-time observing data of 210 Chinese national GNSS reference stations to estimate the tropospheric delay, and establishes ZWD grid model in the country wide. In order to analyze the influence of tropospheric grid product on wide-area real-time PPP, this paper compares the method of taking ZWD grid product as a constraint with the model correction method. The results show that the ZWD grid product estimated based on the national reference stations can improve PPP accuracy and convergence speed. The accuracy in the north (N), east (E) and up (U) direction increase by 31.8 %,15.6 % and 38.3 %, respectively. As with the convergence speed, the accuracy of U direction experiences the most improvement.

Influence of corona discharge on the ozone budget in the tropical free troposphere: a case study of deep convection during GABRIEL

Science.gov (United States)

Bozem, H.; Fischer, H.; Gurk, C.; Schiller, C. L.; Parchatka, U.; Koenigstedt, R.; Stickler, A.; Martinez, M.; Harder, H.; Kubistin, D.; Williams, J.; Eerdekens, G.; Lelieveld, J.

2014-09-01

Convective redistribution of ozone and its precursors between the boundary layer (BL) and the free troposphere (FT) influences photochemistry, in particular in the middle and upper troposphere (UT). We present a case study of convective transport during the GABRIEL campaign over the tropical rain forest in Suriname in October 2005. During one measurement flight the inflow and outflow regions of a cumulonimbus cloud (Cb) have been characterized. We identified a distinct layer between 9 and 11 km altitude with enhanced mixing ratios of CO, O3, HOx, acetone and acetonitrile. The elevated O3 contradicts the expectation that convective transport brings low-ozone air from the boundary layer to the outflow region. Entrainment of ozone-rich air is estimated to account for 62% (range: 33-91%) of the observed O3. Ozone is enhanced by only 5-6% by photochemical production in the outflow due to enhanced NO from lightning, based on model calculations using observations including the first reported HOx measurements over the tropical rainforest. The "excess" ozone in the outflow is most probably due to direct production by corona discharge associated with lightning. We deduce a production rate of 5.12 × 1028 molecules O3 flash-1 (range: 9.89 × 1026-9.82 × 1028 molecules O3 flash-1), which is at the upper limit of the range reported previously.

Aerosol indirect effects on lightning in the generation of induced NOx and tropospheric ozone over an Indian urban metropolis

Science.gov (United States)

Saha, Upal; Maitra, Animesh; Talukdar, Shamitaksha; Jana, Soumyajyoti

increase in lightning activity is caused by the indirect influx of aerosols, especially in the upper troposphere. This is due to the warming-effect of aerosol forcing via its effect on tropospheric ozone production. Due to the increased production of O3 by lightning-induced NOx and high aerosol loading in the pre-monsoon and monsoon months, the positive climate feedback indicates a warmer climate. As a consequence, convective activity as well as lightning flashes may increase due to this indirect effect of AOD over the region. The generation of induced NOx has a positive correlation (r = 0.723) with the LFR during 2001-2012 over Kolkata. Thus, our results have significant implications for understanding the tropospheric ozone forcing by investigating the coupled aerosol-cloud-chemistry system on the generation of lightning and lightning-induced NOx over the urban metropolis.

Rapid increases in tropospheric ozone production and export from China

NARCIS (Netherlands)

Verstraeten, W.W.; Neu, J.L.; Williams, J.E.; Bowman, K.W.; Worden, J.R.; Boersma, K.F.

2015-01-01

Rapid population growth and industrialization have driven substantial increases in Asian ozone precursor emissions over the past decade1, with highly uncertain impacts on regional and global tropospheric ozone levels. According to ozonesonde measurements2, 3, tropospheric ozone concentrations at two

Physics of the tropospheric radiopropagation

International Nuclear Information System (INIS)

Ajayi, G.O.

1989-02-01

The physics of the tropospheric radiopropagation is presented considering the atmospheric radio refractive index and taking into account the influence of precipitation and the attenuation due to the atmospheric gases. 35 refs, 20 figs, 3 tabs

Evaluation of an active humidification system for inspired gas.

Science.gov (United States)

Roux, Nicolás G; Plotnikow, Gustavo A; Villalba, Darío S; Gogniat, Emiliano; Feld, Vivivana; Ribero Vairo, Noelia; Sartore, Marisa; Bosso, Mauro; Scapellato, José L; Intile, Dante; Planells, Fernando; Noval, Diego; Buñirigo, Pablo; Jofré, Ricardo; Díaz Nielsen, Ernesto

2015-03-01

The effectiveness of the active humidification systems (AHS) in patients already weaned from mechanical ventilation and with an artificial airway has not been very well described. The objective of this study was to evaluate the performance of an AHS in chronically tracheostomized and spontaneously breathing patients. Measurements were quantified at three levels of temperature (T°) of the AHS: level I, low; level II, middle; and level III, high and at different flow levels (20 to 60 L/minute). Statistical analysis of repeated measurements was performed using analysis of variance and significance was set at a P<0.05. While the lowest temperature setting (level I) did not condition gas to the minimum recommended values for any of the flows that were used, the medium temperature setting (level II) only conditioned gas with flows of 20 and 30 L/minute. Finally, at the highest temperature setting (level III), every flow reached the minimum absolute humidity (AH) recommended of 30 mg/L. According to our results, to obtain appropiate relative humidity, AH and T° of gas one should have a device that maintains water T° at least at 53℃ for flows between 20 and 30 L/m, or at T° of 61℃ at any flow rate.

Radiative forcing for changes in tropospheric O3

International Nuclear Information System (INIS)

Grossman, A.S.; Wuebbles, D.J.; Grant, K.E.

1994-06-01

We have evaluated the radiative forcing for assumed changes in tropospheric O 3 in the 500-1650 cm -1 wavenumber range. The radiative forcing calculations were performed as a function of latitude as well as for a globally and seasonally averaged model atmosphere, both in a clear sky approximation and in a model containing a representative cloud distribution. The scenarios involved radiative forcing calculations for O 3 at normal atmospheric abundance and at a tropospheric abundance depleted by 25 ppbv, at each altitude, for all northern hemisphere latitudes. Normal abundances of H 2 O, CO 2 , CH 4 , and N 2 O were included in the calculations. The IR radiative forcing was calculated using a correlated k-distribution radiative transfer model. The tropospheric radiative forcing values are compared to the IPCC formulae for ozone tropospheric forcing as well as other published values to determine the validity of the correlated k-distribution approach to the radiative forcing calculations. The results for the global average atmosphere show agreement with previous results to the order of 10 percent. We conclude that the O 3 forcing is linear in the background abundance and that the radiative forcing for ozone for the globally averaged atmosphere and the latitude averaged radiative forcing in the clear sky approximation are in agreement to within 10 percent. For the case of an atmosphere in which the tropospheric ozone has been depleted by 25 ppbv at all altitudes in the northern hemisphere, the mid latitude zone contributes ∼50 percent of the forcing, tropic zone contributes ∼37 percent of the forcing and the polar zone contributes ∼13 percent of the total forcing

Methyl chloride in the upper troposphere observed by the CARIBIC passenger aircraft observatory: Large-scale distributions and Asian summer monsoon outflow

Science.gov (United States)

Umezawa, T.; Baker, A. K.; Oram, D.; Sauvage, C.; O'Sullivan, D.; Rauthe-Schöch, A.; Montzka, S. A.; Zahn, A.; Brenninkmeijer, C. A. M.

2014-05-01

We present spatial and temporal variations of methyl chloride (CH3Cl) in the upper troposphere (UT) observed mainly by the Civil Aircraft for Regular Investigation of the atmosphere Based on an Instrument Container (CARIBIC) passenger aircraft for the years 2005-2011. The CH3Cl mixing ratio in the UT over Europe was higher than that observed at a European surface baseline station throughout the year, indicative of a persistent positive vertical gradient at Northern Hemisphere midlatitudes. A series of flights over Africa and South Asia show that CH3Cl mixing ratios increase toward tropical latitudes, and the observed UT CH3Cl level over these two regions and the Atlantic was higher than that measured at remote surface sites. Strong emissions of CH3Cl in the tropics combined with meridional air transport through the UT may explain such vertical and latitudinal gradients. Comparisons with carbon monoxide (CO) data indicate that noncombustion sources in the tropics dominantly contribute to forming the latitudinal gradient of CH3Cl in the UT. We also observed elevated mixing ratios of CH3Cl and CO in air influenced by biomass burning in South America and Africa, and the enhancement ratios derived for CH3Cl to CO in those regions agree with previous observations. In contrast, correlations indicate a high CH3Cl to CO ratio of 2.9 ± 0.5 ppt ppb-1 in the Asian summer monsoon anticyclone and domestic biofuel emissions in South Asia are inferred to be responsible. We estimated the CH3Cl emission in South Asia to be 134 ± 23 Gg Cl yr-1, which is higher than a previous estimate due to the higher CH3Cl to CO ratio observed in this study.

Measurement of low-ppm mixing ratios of water vapor in the upper troposphere and lower stratosphere using chemical ionization mass spectrometry

Directory of Open Access Journals (Sweden)

T. D. Thornberry

2013-06-01

Full Text Available A chemical ionization mass spectrometer (CIMS instrument has been developed for the fast, precise, and accurate measurement of water vapor (H2O at low mixing ratios in the upper troposphere and lower stratosphere (UT/LS. A low-pressure flow of sample air passes through an ionization volume containing an α-particle radiation source, resulting in a cascade of ion-molecule reactions that produce hydronium ions (H3O+ from ambient H2O. The production of H3O+ ions from ambient H2O depends on pressure and flow through the ion source, which were tightly controlled in order to maintain the measurement sensitivity independent of changes in the airborne sampling environment. The instrument was calibrated every 45 min in flight by introducing a series of H2O mixing ratios between 0.5 and 153 parts per million (ppm, 10−6 mol mol−1 generated by Pt-catalyzed oxidation of H2 standards while overflowing the inlet with dry synthetic air. The CIMS H2O instrument was deployed in an unpressurized payload area aboard the NASA WB-57F high-altitude research aircraft during the Mid-latitude Airborne Cirrus Properties Experiment (MACPEX mission in March and April 2011. The instrument performed successfully during seven flights, measuring H2O mixing ratios below 5 ppm in the lower stratosphere at altitudes up to 17.7 km, and as low as 3.5 ppm near the tropopause. Data were acquired at 10 Hz and reported as 1 s averages. In-flight calibrations demonstrated a typical sensitivity of 2000 Hz ppm−1 at 3 ppm with a signal to noise ratio (2 σ, 1 s greater than 32. The total measurement uncertainty was 9 to 11%, derived from the uncertainty in the in situ calibrations.

Seasonal Variability of Saturn's Tropospheric Temperatures, Winds and Para-H2 from Cassini Far-IR Spectroscopy

Science.gov (United States)

Fletcher, Leigh N.; Irwin, P. G. J; Achterberg, R. K.; Orton, G. S.; Flasar, F. M.

2015-01-01

Far-IR 16-1000 micrometer spectra of Saturn's hydrogen-helium continuum measured by Cassini's Composite Infrared Spectrometer (CIRS) are inverted to construct a near-continuous record of upper tropospheric (70-700 mbar) temperatures and para-H2 fraction as a function of latitude, pressure and time for a third of a saturnian year (2004-2014, from northern winter to northern spring). The thermal field reveals evidence of reversing summertime asymmetries superimposed onto the belt/zone structure. The temperature structure is almost symmetric about the equator by 2014, with seasonal lag times that increase with depth and are qualitatively consistent with radiative climate models. Localised heating of the tropospheric hazes (100-250 mbar) create a distinct perturbation to the temperature profile that shifts in magnitude and location, declining in the autumn hemisphere and growing in the spring. Changes in the para-H2 (f(sub p)) distribution are subtle, with a 0.02-0.03 rise over the spring hemisphere (200-500 mbar) perturbed by (i) low-f(sub p) air advected by both the springtime storm of 2010 and equatorial upwelling; and (ii) subsidence of high-f(sub p) air at northern high latitudes, responsible for a developing north-south asymmetry in f(sub p). Conversely, the shifting asymmetry in the para-H2 disequilibrium primarily reflects the changing temperature structure (and hence the equilibrium distribution of f(sub p)), rather than actual changes in f(sub p) induced by chemical conversion or transport. CIRS results interpolated to the same point in the seasonal cycle as re-analysed Voyager-1 observations (early northern spring) show qualitative consistency from year to year (i.e., the same tropospheric asymmetries in temperature and f(sub p)), with the exception of the tropical tropopause near the equatorial zones and belts, where downward propagation of a cool temperature anomaly associated with Saturn's stratospheric oscillation could potentially perturb tropopause

On the relationship between tropospheric conditions and widespread hot days in Iran

Science.gov (United States)

Asakereh, Hossein; Shadman, Hassan

2018-01-01

The present study investigated how the tropospheric conditions relate to the occurrence of widespread hot days (WHD) in Iran using the data of maximum daily temperature and other tropospheric variables. To better understand the tropospheric conditions during WHD, different patterns of tropospheric circulation were examined systematically. Four tropospheric types were identified based on sea level pressure (SLP). SLP, 500 hPa height, anomaly patterns, and warm advection maps were constructed for typical days of each group. The tropospheric conditions associated with hot days occurred simultaneously with a low-pressure system at sea level, a ridge at middle troposphere over Iran, and a pronounced trough over the Mediterranean Sea at 500 hPa. These conditions caused air mass from subtropical regions toward Iran. That is, northward, northeastward, and even eastward winds injected heat with warm origins toward the country. Hot days compounded by drought conditions have affected many parts of the country in different ways such as decrease in the agricultural products in numerous areas and significant discharge reduction in many rivers. The society is also very likely to face considerable challenges to cope with hot days. The findings of the study can be utilized in climate modeling and climate prediction of hot days in the country. Accordingly, water and electricity consumption can be planned with further precision and water consumption can be managed in crises.

Clinical evidence on high flow oxygen therapy and active humidification in adults.

Science.gov (United States)

Gotera, C; Díaz Lobato, S; Pinto, T; Winck, J C

2013-01-01

Recently there has been growing interest in an alternative to conventional oxygen therapy: the heated, humidified high flow nasal cannula oxygen therapy (HFNC). A number of physiological effects have been described with HFNC: pharyngeal dead space washout, reduction of nasopharyngeal resistance, a positive expiratory pressure effect, an alveolar recruitment, greater humidification, more comfort and better tolerance by the patient, better control of FiO2 and mucociliary clearance. There is limited experience of HFNC in adults. There are no established guidelines or decision-making pathways to guide use of the HFNC therapy for adults. In this article we review the existing evidence of HFNC oxygen therapy in adult patients, its advantages, limitations and the current literature on clinical applications. Further research is required to determine the long-term effect of this therapy and identify the adult patient population to whom it is most beneficial. Copyright © 2013 Sociedade Portuguesa de Pneumologia. Published by Elsevier España. All rights reserved.

Impact of NO2 Profile Shape in OMI Tropospheric NO2 Retrievals

Science.gov (United States)

Lamsal, Lok; Krotkov, Nickolay A.; Pickering, K.; Schwartz, W. H.; Celarier, E. A.; Bucsela, E. J.; Gleason, J. F.; Philip, S.; Nowlan, C.; Martin, R. V.;

Tropospheric Emissions: Monitoring of Pollution (TEMPO)

Science.gov (United States)

Chance, Kelly; Liu, Xiong; Suleiman, Raid M.; Flittner, David E.; Al-Saadi, Jassim; Janz, Scott J.

2014-06-01

TEMPO, selected by NASA as the first Earth Venture Instrument, will measure atmospheric pollution for greater North America from space using ultraviolet and visible spectroscopy. TEMPO measures from Mexico City to the Canadian oil sands, and from the Atlantic to the Pacific, hourly and at high spatial resolution. TEMPO provides a tropospheric measurement suite that includes the key elements of tropospheric air pollution chemistry. Measurements are from geostationary (GEO) orbit, to capture the inherent high variability in the diurnal cycle of emissions and chemistry. The small product spatial footprint resolves pollution sources at sub-urban scale. Together, this temporal and spatial resolution improves emission inventories, monitors population exposure, and enables effective emission-control strategies. TEMPO takes advantage of a GEO host spacecraft to provide a modest-cost mission that measures the spectra required to retrieve O3, NO2, SO2, H2CO, C2H2O2, H2O, aerosols, cloud parameters, and UVB radiation. TEMPO thus measures the major elements, directly or by proxy, in the tropospheric O3 chemistry cycle. Multi-spectral observations provide sensitivity to O3 in the lowermost troposphere, reducing uncertainty in air quality predictions by 50 %. TEMPO quantifies and tracks the evolution of aerosol loading. It provides near-real-time air quality products that will be made widely, publicly available. TEMPO makes the first tropospheric trace gas measurements from GEO, by building on the heritage of five spectrometers flown in low-earth-orbit (LEO). These LEO instruments measure the needed spectra, although at coarse spatial and temporal resolutions, to the precisions required for TEMPO and use retrieval algorithms developed for them by TEMPO Science Team members and currently running in operational environments. This makes TEMPO an innovative use of a well-proven technique, able to produce a revolutionary data set. TEMPO provides much of the atmospheric measurement

Measured and modeled humidification factors of fresh smoke particles from biomass burning: role of inorganic constituents

Directory of Open Access Journals (Sweden)

J. L. Hand

2010-07-01

Full Text Available During the 2006 FLAME study (Fire Laboratory at Missoula Experiment, laboratory burns of biomass fuels were performed to investigate the physico-chemical, optical, and hygroscopic properties of fresh biomass smoke. As part of the experiment, two nephelometers simultaneously measured dry and humidified light scattering coefficients (b_sp(dry and b_sp(RH, respectively in order to explore the role of relative humidity (RH on the optical properties of biomass smoke aerosols. Results from burns of several biomass fuels from the west and southeast United States showed large variability in the humidification factor (f(RH=b_sp(RH/b_sp(dry. Values of f(RH at RH=80–85% ranged from 0.99 to 1.81 depending on fuel type. We incorporated measured chemical composition and size distribution data to model the smoke hygroscopic growth to investigate the role of inorganic compounds on water uptake for these aerosols. By assuming only inorganic constituents were hygroscopic, we were able to model the water uptake within experimental uncertainty, suggesting that inorganic species were responsible for most of the hygroscopic growth. In addition, humidification factors at 80–85% RH increased for smoke with increasing inorganic salt to carbon ratios. Particle morphology as observed from scanning electron microscopy revealed that samples of hygroscopic particles contained soot chains either internally or externally mixed with inorganic potassium salts, while samples of weak to non-hygroscopic particles were dominated by soot and organic constituents. This study provides further understanding of the compounds responsible for water uptake by young biomass smoke, and is important for accurately assessing the role of smoke in climate change studies and visibility regulatory efforts.

Energy efficient and adiabatic humidification. Reversed osmosis principle purifies water; Energiezuinig en adiabatisch bevochtigen. Omgekeerd-osmose principe zuivert water

Energy Technology Data Exchange (ETDEWEB)

Brands, R. [Cumulus Nederland, Cuijk (Netherlands)

2006-11-15

For decades air conditioners are equipped with humidifiers. A large number of humidifier types are available. Adiabatic humidification is an energy efficient technique, although it is important to control the installation conditions, water treatment (reversed osmosis) and the risk of legionella. [Dutch] Al decennia lang worden er luchtbehandelingkasten gebouwd met een bevochtigingssectie. Door de jaren heen is een enorme verscheidenheid ontstaan van bevochtigingssystemen. Adiabatische bevochtiging staat in de belangstelling vanwege het lagere energiegebruik. Hierbij moeten de installatievoorwaarden, de waterbehandeling (omgekeerde osmose) en het legionellarisico goed in de gaten worden gehouden.

Tropospheric ozone climatology over Beijing: analysis of aircraft data from the MOZAIC program

Directory of Open Access Journals (Sweden)

A. J. Ding

2008-01-01

Full Text Available Ozone (O₃ profiles recorded over Beijing from 1995 to 2005 by the Measurement of Ozone and Water Vapor by Airbus In-Service Aircraft (MOZAIC program were analyzed to provide a first climatology of tropospheric O₃ over Beijing and the North China Plains (NCPs, one of the most populated and polluted regions in China. A pooled method was adopted in the data analysis to reduce the influence of irregular sampling frequency. The tropospheric O₃ over Beijing shows a seasonal and vertical distribution typical of mid-latitude locations in the Northern Hemisphere, but has higher daytime concentrations in the lower troposphere, when compared to New York City, Tokyo, and Paris at similar latitude. The tropospheric O₃ over Beijing exhibits a common summer maximum and a winter minimum, with a broad summer maximum in the middle troposphere and a narrower early summer (June peak in the lower troposphere. Examination of meteorological and satellite data suggests that the lower tropospheric O₃ maximum in June is a result of strong photochemical production, transport of regional pollution, and possibly also more intense burnings of biomass in Central-Eastern China. Trajectory analysis indicates that in summer the regional pollution from the NCPs, maybe mixed with urban plumes from Beijing, played important roles on the high O₃ concentrations in the boundary layer, but had limited impact on the O₃ concentrations in the middle troposphere. A comparison of the data recorded before and after 2000 reveals that O₃ in the lower troposphere over Beijing had a strong positive trend (approximately 2% per year from 1995 to 2005 in contrast to a flat or a decreasing trend over Tokyo, New York City, and Paris, indicating worsening photochemical pollution in Beijing and the NCPs.

Tropospheric ozone observations - How well can we assess tropospheric ozone changes?

Science.gov (United States)

Tarasick, D. W.; Galbally, I. E.; Ancellet, G.; Leblanc, T.; Wallington, T. J.; Ziemke, J. R.; Steinbacher, M.; Stähelin, J.; Vigouroux, C.; Hannigan, J. W.; García, O. E.; Foret, G.; Zanis, P.; Liu, X.; Weatherhead, E. C.; Petropavlovskikh, I. V.; Worden, H. M.; Osman, M.; Liu, J.; Lin, M.; Cooper, O. R.; Schultz, M. G.; Granados-Muñoz, M. J.; Thompson, A. M.; Cuesta, J.; Dufour, G.; Thouret, V.; Hassler, B.; Trickl, T.

2017-12-01

Since the early 20th century, measurements of ozone in the free troposphere have evolved and changed. Data records have different uncertainties and biases, and differ with respect to coverage, information content, and representativeness. Almost all validation studies employ ECC ozonesondes. These have been compared to UV-absorption measurements in a number of intercomparison studies, and show a modest ( 1-5%) high bias in the troposphere, with an uncertainty of 5%, but no evidence of a change over time. Umkehr, lidar, FTIR, and commercial aircraft all show modest low biases relative to the ECCs, and so -- if the ECC biases are transferable -- all agree within 1σ with the modern UV standard. Relative to the UV standard, Brewer-Mast sondes show a 20% increase in sensitivity from 1970-1995, while Japanese KC sondes show an increase of 5-10%. Combined with the shift of the global ozonesonde network to ECCs, this can induce a false positive trend, in analyses based on sonde data. Passive sounding methods -- Umkehr, FTIR and satellites -- have much lower vertical resolution than active methods, and this can limit the attribution of trends. Satellite biases are larger than those of other measurement systems, ranging between -10% and +20%, and standard deviations are large: about 10-30%, versus 5-10% for sondes, aircraft, lidar and ground-based FTIR. There is currently little information on measurement drift for satellite measurements of tropospheric ozone. This is an evident area of concern if satellite retrievals are used for trend studies. The importance of ECC sondes as a transfer standard for satellite validation means that efforts to homogenize existing records, by correcting for known changes and by adopting strict standard operating procedures, should continue, and additional research effort should be put into understanding and reducing sonde uncertainties. Representativeness is also a potential source of large errors, which are difficult to quantify. The global

Tropospheric radiative forcing of CH4

International Nuclear Information System (INIS)

Grossman, A.S.; Grant, K.E.

1994-04-01

We have evaluated the tropospheric radiative forcing of CH 4 in the 0-3000 cm -1 wavenumber range and compared this with prior published calculations. The atmospheric test cases involved perturbed methane scenarios in both a McClatchey mid latitude, summer, clear sky approximation, model atmosphere, as well as a globally and seasonally averaged model atmosphere containing a representative cloud distribution. The scenarios involved pure CH 4 radiative forcing and CH 4 plus a mixture of H 2 O, CO 2 , O 3 , and N 2 O. The IR radiative forcing was calculated using a correlated k-distribution transmission model. The major purposes of this paper are to first, use the correlated k-distribution model to calculate the tropospheric radiative forcing for CH 4 , as the only radiatively active gas, and in a mixture with H 2 O, CO 2 , O 3 , and N 2 O, for a McClatchey mid-latitude summer, clear-sky model atmosphere, and to compare the results to those obtained in the studies mentioned above. Second, we will calculate the tropospheric methane forcing in a globally and annually averaged atmosphere with and without a representative cloud distribution in order to validate the conjecture given in IPCC (1990) that the inclusion of clouds in the forcing calculations results in forcing values which are approximately 20 percent less than those obtained using clear sky approximations

Airborne differential absorption lidar for water vapour measurements in the upper troposphere and lower stratosphere in the spectral region around 940 nm

Energy Technology Data Exchange (ETDEWEB)

Poberaj, G.

2000-07-01

Two all-solid-state laser systems were developed and studied in detail to optimise their performance for an airborne water vapour differential absorption lidar (DIAL). Their special features are high average output powers and excellent spectral properties in the 940-nm spectral region relevant for monitoring very low water vapour contents in the upper troposphere and lower stratosphere. One system is an injection-seeded pulsed Ti:sapphire ring laser with a spectral bandwidth of 105 MHz and an average power of 1.1 W. The other system is an injection-seeded optical parametric oscillator (OPO) in a ring configuration. Using KTP as nonlinear crystal, a signal output with a spectral bandwidth of 140 MHz and an average power of 1.2 W was achieved. Both systems, the Ti:sapphire ring laser and the KTP OPO, possess spectral purity values higher than 99%. The pump source for these systems is a frequency doubled diode-pumped Nd:YAG laser operating at a repetition rate of 100 Hz. The KTP OPO system has been used as a transmitter in a new airborne water vapour DIAL instrument. For the first time, measurements of two-dimensional water vapour distributions with a high vertical (500 m) and horizontal (20 km) resolution across several potential vorticity streamers were performed. Very low water vapour mixing ratios (10-50 ppmv) and strong gradients were observed in the tropopause region. The sensitivity of the DIAL instrument in the centre of a stratospheric intrusion ranges from 3% in the near field to 12% in the far field (4 km). The first comparison experiments with in situ measuring instruments show a good agreement. Considerable differences are found between DIAL measurements and data obtained from the ECMWF operational analyses and a mesoscale numerical model. (orig.)

A tropospheric ozone maximum over the equatorial Southern Indian Ocean

Directory of Open Access Journals (Sweden)

L. Zhang

2012-05-01

Full Text Available We examine the distribution of tropical tropospheric ozone (O₃ from the Microwave Limb Sounder (MLS and the Tropospheric Emission Spectrometer (TES by using a global three-dimensional model of tropospheric chemistry (GEOS-Chem. MLS and TES observations of tropospheric O₃ during 2005 to 2009 reveal a distinct, persistent O₃ maximum, both in mixing ratio and tropospheric column, in May over the Equatorial Southern Indian Ocean (ESIO. The maximum is most pronounced in 2006 and 2008 and less evident in the other three years. This feature is also consistent with the total column O₃ observations from the Ozone Mapping Instrument (OMI and the Atmospheric Infrared Sounder (AIRS. Model results reproduce the observed May O₃ maximum and the associated interannual variability. The origin of the maximum reflects a complex interplay of chemical and dynamic factors. The O₃ maximum is dominated by the O₃ production driven by lightning nitrogen oxides (NO_x emissions, which accounts for 62% of the tropospheric column O₃ in May 2006. We find the contribution from biomass burning, soil, anthropogenic and biogenic sources to the O₃ maximum are rather small. The O₃ productions in the lightning outflow from Central Africa and South America both peak in May and are directly responsible for the O₃ maximum over the western ESIO. The lightning outflow from Equatorial Asia dominates over the eastern ESIO. The interannual variability of the O₃ maximum is driven largely by the anomalous anti-cyclones over the southern Indian Ocean in May 2006 and 2008. The lightning outflow from Central Africa and South America is effectively entrained by the anti-cyclones followed by northward transport to the ESIO.

Ozone in the Tropical Troposphere

NARCIS (Netherlands)

Peters, Wouter

2002-01-01

The aim of the research presented here is to acquire knowledge of the past, present, and future composition, stability, sensitivity, and variability of the troposphere. We focus mostly on the tropical regions because it has received little attention so far, measurements here are scarce, and large

Applications of Satellite Observations of Tropospheric Composition

Science.gov (United States)

Monks, Paul S.; Beirle, Steffen

A striking feature of the field of tropospheric composition is the sheer number of chemical species that have been detected and measured with satellite instruments. The measurements have found application both in atmospheric chemistry itself, providing evidence, for example, of unexpected cryochemistry in the Arctic regions, and also in environmental monitoring with, for example, the observed growth in NO2 emissions over eastern Asia. Chapter 8 gives an overview of the utility of satellite observations for measuring tropospheric composition, dealing with each of the many compounds seen in detail. A comprehensive compound by compound table of the many studies performed is a most useful feature.

Tropospheric emissions: Monitoring of pollution (TEMPO)

Science.gov (United States)

Zoogman, P.; Liu, X.; Suleiman, R. M.; Pennington, W. F.; Flittner, D. E.; Al-Saadi, J. A.; Hilton, B. B.; Nicks, D. K.; Newchurch, M. J.; Carr, J. L.; Janz, S. J.; Andraschko, M. R.; Arola, A.; Baker, B. D.; Canova, B. P.; Chan Miller, C.; Cohen, R. C.; Davis, J. E.; Dussault, M. E.; Edwards, D. P.; Fishman, J.; Ghulam, A.; González Abad, G.; Grutter, M.; Herman, J. R.; Houck, J.; Jacob, D. J.; Joiner, J.; Kerridge, B. J.; Kim, J.; Krotkov, N. A.; Lamsal, L.; Li, C.; Lindfors, A.; Martin, R. V.; McElroy, C. T.; McLinden, C.; Natraj, V.; Neil, D. O.; Nowlan, C. R.; O`Sullivan, E. J.; Palmer, P. I.; Pierce, R. B.; Pippin, M. R.; Saiz-Lopez, A.; Spurr, R. J. D.; Szykman, J. J.; Torres, O.; Veefkind, J. P.; Veihelmann, B.; Wang, H.; Wang, J.; Chance, K.

2017-01-01

TEMPO was selected in 2012 by NASA as the first Earth Venture Instrument, for launch between 2018 and 2021. It will measure atmospheric pollution for greater North America from space using ultraviolet and visible spectroscopy. TEMPO observes from Mexico City, Cuba, and the Bahamas to the Canadian oil sands, and from the Atlantic to the Pacific, hourly and at high spatial resolution ( 2.1 km N/S×4.4 km E/W at 36.5°N, 100°W). TEMPO provides a tropospheric measurement suite that includes the key elements of tropospheric air pollution chemistry, as well as contributing to carbon cycle knowledge. Measurements are made hourly from geostationary (GEO) orbit, to capture the high variability present in the diurnal cycle of emissions and chemistry that are unobservable from current low-Earth orbit (LEO) satellites that measure once per day. The small product spatial footprint resolves pollution sources at sub-urban scale. Together, this temporal and spatial resolution improves emission inventories, monitors population exposure, and enables effective emission-control strategies. TEMPO takes advantage of a commercial GEO host spacecraft to provide a modest cost mission that measures the spectra required to retrieve ozone (O3), nitrogen dioxide (NO2), sulfur dioxide (SO2), formaldehyde (H2CO), glyoxal (C2H2O2), bromine monoxide (BrO), IO (iodine monoxide), water vapor, aerosols, cloud parameters, ultraviolet radiation, and foliage properties. TEMPO thus measures the major elements, directly or by proxy, in the tropospheric O3 chemistry cycle. Multi-spectral observations provide sensitivity to O3 in the lowermost troposphere, substantially reducing uncertainty in air quality predictions. TEMPO quantifies and tracks the evolution of aerosol loading. It provides these near-real-time air quality products that will be made publicly available. TEMPO will launch at a prime time to be the North American component of the global geostationary constellation of pollution monitoring

Future changes in large-scale transport and stratosphere-troposphere exchange

Science.gov (United States)

Abalos, M.; Randel, W. J.; Kinnison, D. E.; Garcia, R. R.

2017-12-01

Future changes in large-scale transport are investigated in long-term (1955-2099) simulations of the Community Earth System Model - Whole Atmosphere Community Climate Model (CESM-WACCM) under an RCP6.0 climate change scenario. We examine artificial passive tracers in order to isolate transport changes from future changes in emissions and chemical processes. The model suggests enhanced stratosphere-troposphere exchange in both directions (STE), with decreasing tropospheric and increasing stratospheric tracer concentrations in the troposphere. Changes in the different transport processes are evaluated using the Transformed Eulerian Mean continuity equation, including parameterized convective transport. Dynamical changes associated with the rise of the tropopause height are shown to play a crucial role on future transport trends.

Global model of zenith tropospheric delay proposed based on EOF analysis

Science.gov (United States)

Sun, Langlang; Chen, Peng; Wei, Erhu; Li, Qinzheng

2017-07-01

Tropospheric delay is one of the main error budgets in Global Navigation Satellite System (GNSS) measurements. Many empirical correction models have been developed to compensate this delay, and models which do not require meteorological parameters have received the most attention. This study established a global troposphere zenith total delay (ZTD) model, called Global Empirical Orthogonal Function Troposphere (GEOFT), based on the empirical orthogonal function (EOF, also known as geographically weighted PCAs) analysis method and the Global Geodetic Observing System (GGOS) Atmosphere data from 2012 to 2015. The results showed that ZTD variation could be well represented by the characteristics of the EOF base function Ek and associated coefficients Pk. Here, E1 mainly signifies the equatorial anomaly; E2 represents north-south asymmetry, and E3 and E4 reflects regional variation. Moreover, P1 mainly reflects annual and semiannual variation components; P2 and P3 mainly contains annual variation components, and P4 displays semiannual variation components. We validated the proposed GEOFT model using tropospheric delay data of GGOS ZTD grid data and the tropospheric product of the International GNSS Service (IGS) over the year 2016. The results showed that GEOFT model has high accuracy with bias and RMS of -0.3 and 3.9 cm, respectively, with respect to the GGOS ZTD data, and of -0.8 and 4.1 cm, respectively, with respect to the global IGS tropospheric product. The accuracy of GEOFT demonstrating that the use of the EOF analysis method to characterize ZTD variation is reasonable.

Tropospheric ozone and biomass burning in intertropical Africa

International Nuclear Information System (INIS)

Cros, B.; Nganga, D.; Delmas, R.A.; Fontan, J.

1991-01-01

To obtain a better understanding of tropospheric ozone's behavior in the equatorial belt of Africa, surface ozone measurements were made in the northern Congo (forest region) and on the other side of the equator in a savanna area. The data show a seasonal cycle with maximum values during the dry season: January and February in the northern tropics and June to October in the southern ones. Satellite data are needed to explain the eventual disappearance or non-appearance of a maximum of total tropospheric ozone during the northern dry season

New capability for ozone dial profiling measurements in the troposphere and lower stratosphere from aircraft

Science.gov (United States)

Hair, Johnathan; Hostetler, Chris; Cook, Anthony; Harper, David; Notari, Anthony; Fenn, Marta; Newchurch, Mike; Wang, Lihua; Kuang, Shi; Knepp, Travis; Burton, Sharon; Ferrare, Richard; Butler, Carolyn; Collins, Jim; Nehrir, Amin

2018-04-01

Recently, we successfully demonstrated a new compact and robust ozone DIAL lidar for smaller aircraft such as the NASA B200 and the ER-2 high-altitude aircraft. This is the first NASA airborne lidar to incorporate advanced solid-state lasers to produce the required power at the required ultraviolet wavelengths, and is compact and robust enough to operate nearly autonomously on the high-altitude ER-2 aircraft. This technology development resulted in the first new NASA airborne ozone DIAL instrument in more than 15 years. The combined ozone, aerosol, and clouds measurements provide valuable information on the chemistry, radiation, and dynamics of the atmosphere. In particular, from the ER-2 it offers a unique capability to study the upper troposphere and lower stratosphere.

Carbon monoxide and methane in the North American Arctic and Subarctic troposphere - July-August 1988

Science.gov (United States)

Harriss, Robert C.; Sachse, Glen W.; Hill, Gerald F.; Wade, Larry; Bartlett, Karen B.; Collins, James E.; Steele, L. P.; Novelli, Paul C.

1992-01-01

Enhanced concentrations of CH4 in the unpolluted atmospheric mixed layer over both Arctic and subarctic tundra landscapes are documented here using data from the NASA Arctic Boundary Layer Expedition (ABLE 3A). The CH4 concentration gradients were determined mainly by interactions of biogenic emission from wet tundra and turbulent mixing proceses. The gradient were most frequently associated with intrusion of upper tropospheric or stratospheric air into the midtroposphere, emissions from forest and tundra fires, and long-range transport of enhanced concentration of these gases from unidentified sources. Summertime haze layers exhibited midtropospheric enhancements of CH4 similar to those measured in winter Arctic events. The observations confirm the importance of Arctic and Subarctic wetland environments as a regional source of global atmospheric CH4.

New capability for ozone dial profiling measurements in the troposphere and lower stratosphere from aircraft

Directory of Open Access Journals (Sweden)

Hair Johnathan

2018-01-01

Full Text Available Recently, we successfully demonstrated a new compact and robust ozone DIAL lidar for smaller aircraft such as the NASA B200 and the ER-2 high-altitude aircraft. This is the first NASA airborne lidar to incorporate advanced solid-state lasers to produce the required power at the required ultraviolet wavelengths, and is compact and robust enough to operate nearly autonomously on the high-altitude ER-2 aircraft. This technology development resulted in the first new NASA airborne ozone DIAL instrument in more than 15 years. The combined ozone, aerosol, and clouds measurements provide valuable information on the chemistry, radiation, and dynamics of the atmosphere. In particular, from the ER-2 it offers a unique capability to study the upper troposphere and lower stratosphere.

Interactive chemistry in the Laboratoire de Météorologie Dynamique general circulation model: model description and impact analysis of biogenic hydrocarbons on tropospheric chemistry

Directory of Open Access Journals (Sweden)

G. A. Folberth

2006-01-01

-INCA calculates an increase of PAN surface mixing ratios ranging from 75 to 750 pptv and 10 to 250 pptv during northern hemispheric summer and winter, respectively. Acetone and methanol are found to play a significant role in the upper troposphere/lower stratosphere (UT/LS budget of peroxy radicals. Calculations with LMDz-INCA show an increase in HOx concentrations region of 8 to 15% and 10 to 15% due to methanol and acetone biogenic surface emissions, respectively. The model has been used to estimate the global tropospheric CO budget. A global CO source of 3019 Tg CO yr-1 is estimated. This source divides into a primary source of 1533 Tg CO yr-1 and secondary source of 1489 Tg CO yr-1 deriving from VOC photooxidation. Global VOC-to-CO conversion efficiencies of 90% for methane and between 20 and 45% for individual VOC are calculated by LMDz-INCA.

An investigation of the processes controlling ozone in the upper stratosphere

International Nuclear Information System (INIS)

Patten, K.O. Jr.; Connell, P.S.; Kinnison, D.E.; Wuebbles, D.J.; Waters, J.; Froidevaux, L.; Slanger, T.G.

1992-01-01

Photolysis of vibrationally excited oxygen produced by ultraviolet photolysis of ozone in the upper stratosphere is incorporated into the Lawrence Livermore National Laboratory 2-D zonally averaged chemical-radiative-transport model of the troposphere and stratosphere. The importance of this potential contributor of odd oxygen to the concentration of ozone is evaluated based upon recent information on vibrational distributions of excited oxygen and upon preliminary studies of energy transfer from the excited oxygen. When the energy transfer rate constants of previous work are assumed, increases in model ozone concentrations of up to 40 percent in the upper stratosphere are found, and the ozone concentrations of the model agree with measurements, including data from the Upper Atmosphere Research Satellite. However, the increase is about 0.4 percent when the larger energy transfer rate constants suggested by more recent experimental work are applied in the model. This indicates the importance of obtaining detailed information on vibrationally excited oxygen properties, particularly the state-specific energy transfer rate constants, to evaluation of tills precess for stratospheric modeling

Humidification of base flow gas during adult high-frequency oscillatory ventilation: an experimental study using a lung model.

Science.gov (United States)

Shiba, Naoki; Nagano, Osamu; Hirayama, Takahiro; Ichiba, Shingo; Ujike, Yoshihito

2012-01-01

In adult high-frequency oscillatory ventilation (HFOV) with an R100 artificial ventilator, exhaled gas from patient's lung may warm the temperature probe and thereby disturb the humidification of base flow (BF) gas. We measured the humidity of BF gas during HFOV with frequencies of 6, 8 and 10 Hz, maximum stroke volumes (SV) of 285, 205, and 160 ml at the respective frequencies, and, BFs of 20, 30, 40 l/min using an original lung model. The R100 device was equipped with a heated humidifier, Hummax Ⅱ, consisting of a porous hollow fiber in circuit. A 50-cm length of circuit was added between temperature probe (located at 50 cm proximal from Y-piece) and the hollow fiber. The lung model was made of a plastic container and a circuit equipped with another Hummax Ⅱ. The lung model temperature was controlled at 37℃. The Hummax Ⅱ of the R100 was inactivated in study-1 and was set at 35℃ or 37℃ in study-2. The humidity was measured at the distal end of the added circuit in study-1 and at the proximal end in study-2. In study-1, humidity was detected at 6 Hz (SV 285 ml) and BF 20 l/min, indicating the direct reach of the exhaled gas from the lung model to the temperature probe. In study-2 the absolute humidity of the BF gas decreased by increasing SV and by increasing BF and it was low with setting of 35℃. In this study setting, increasing the SV induced significant reduction of humidification of the BF gas during HFOV with R100.

Tropospheric Delay from VLBI and GNSS Measurements

Science.gov (United States)

Gubanov, V. S.

2018-02-01

Using an updated version of the QUASAR software package developed at the Institute of Applied Astronomy of the Russian Academy of Sciences, we have processed the VLBI observations within the international CONT14 program (May 6-20, 2014), in which a global network of 17 stations was involved (a total of 250 000 observations). The package update concerned the optimization of data structure and the refinement of stochastic models for the random variations in wet tropospheric delay and atomic clock difference. The main goal of this paper is to compare the VLBI determinations of the tropospheric delay with its independent determinations using global navigation satellite systems (GNSS). We show that both these determinations agree well between themselves only in the case of a global analysis of the VLBI observations, where the VLBI station coordinates are also refined, along with the tropospheric delay and the clock synchronization and Earth orientation parameters. If, alternatively, the station coordinates are insufficiently accurate and are not refined from VLBI observations, then it is appropriate not to determine the tropospheric delay from these observations, but to take it from the publicly accessible independent GNSS data. However, this requires that the VLBI and GNSS techniques operate simultaneously at a common observing site. We have established the shortcomings of the universally accepted method of stabilizing the global solution associated with the absence of a criterion for choosing reference stations and radio sources. Two ways of their elimination are proposed: (i) introducing a coordinated list of weight factors for the errors in the coordinates of such stations and sources into the stabilization algorithm and (ii) adopting a coordinated list of stations and sources the refinement of whose coordinates is not required at all for a certain time.

Solar desalination using humidification dehumidification processes. Part I. A numerical investigation

International Nuclear Information System (INIS)

Nafey, A.S.; Fath, H.E.S.; El-Helaby, S.O.; Soliman, A.M.

2004-01-01

A numerical investigation of a humidification dehumidification desalination (HDD) process using solar energy is presented. The HDD system consists mainly of a concentrating solar water heating collector, flat plate solar air heating collector, humidifying tower and dehumidifying exchanger. Two separate circulating loops constitute the HDD system, the first for heating the feed water and the second for heating air. A mathematical model is developed, simulating the HDD system, to study the influence of the different system configurations, weather and operating conditions on the system productivity. The model validity is examined by comparing the theoretical and experimental results of the same authors. It is found that the results of the developed mathematical model are in good agreement with the experimental results and other published works. The results show also that the productivity of the unit is strongly influenced by the air flow rate, cooling water flow rate and total solar energy incident through the day. Wind speed and ambient temperature variations show a very small effect on the system productivity. In addition, the obtained results indicate that the solar water collector area strongly affects the system productivity, more so than the solar air collector area

Solar desalination system of combined solar still and humidification-dehumidification unit

Science.gov (United States)

Ghazy, Ahmed; Fath, Hassan E. S.

2016-11-01

Solar stills, as a simple technology, have many advantages such as simple design; unsophisticated fabrication; low capital and operation costs and easily maintained. However, their low daily production has put constraints on their usage. A radical improvement in the performance of solar stills can be achieved by the partial recovery of the energy losses from the glass cover of the still. This paper simulates a direct solar distillation system of combined solar still with an air heating humidification-dehumidification (HDH) sub-system. The main objective of the Still-HDH system is to improve the productivity and thermal efficiency of the conventional solar still by partially recovering the still energy losses to the ambient for additional water production. Various procedures have been employed to improve the thermal performance of the integrated system by recovering heat losses from one component in another component of the system. Simulations have been carried out for the performance of the Still-HDH system under different weather conditions. A comparison has been held between the Still-HDH system and a conventional solar still of the same size and under the same operating conditions.

A new cavity ring-down instrument for airborne monitoring of N2O5, NO3, NO2 and O3 in the upper troposphere lower stratosphere

Science.gov (United States)

Ruth, Albert A.; Brown, Steven S.; Dinesan, Hemanth; Dubé, William P.; Goulette, Marc; Hübler, Gerhard; Orphal, Johannes; Zahn, Andreas

2016-04-01

The chemistry of NO3 and N2O5 is important to the regulation of both tropospheric and stratospheric ozone. In situ detection of NO3 and N2O5 in the upper troposphere lower stratosphere (UTLS) represents a new scientific direction as the only previous measurements of these species in this region of the atmosphere has been via remote sensing techniques. Because both the sources and the sinks for NO3 and N2O5 are potentially stratified spatially, their mixing ratios, and their influence on nitrogen oxide and ozone transport and loss at night can show large variability as a function of altitude. Aircraft-based measurements of heterogeneous N2O5 uptake in the lower troposphere have uncovered a surprising degree of variability in the uptake coefficient [1], but there are no corresponding high altitude measurements.The UTLS is routinely sampled by the IAGOS-CARIBIC program (Civil Aircraft for the Regular Investigation of the atmosphere Based on an Instrument Container, www.caribic-atmospheric.com), a European infrastructural program with the aim of studying the chemistry and transport across this part of the atmosphere. An airfreight container with 15 different automated instruments from 8 European research partners is utilized on board a commercial Lufthansa airbus 340-600 to monitor ~ 100 atmospheric species (trace gases and aerosol parameters) in the UTLS. The instrumentation in the CARIBIC container is now to be supplemented by a new cavity ring-down device for monitoring nitrogen oxides, jointly developed by researchers from Cork (Ireland), Boulder (USA) and Karlsruhe (Germany). The compact and light-weight instrument is designed to monitor not only NO3 and N2O5, but also NO2 and O3. The detection is based on 4 high-finesse optical cavities (cavity length ~ 44 cm). Two cavities are operated at 662 nm (maximum absorption of NO3), the other two at 405 nm (maximum absorption of NO2). The inlet to one of the (662)-cavities is heated in order to thermally decompose N2O5

Tropospheric chemistry research in the U.S.: 1991-1994

Science.gov (United States)

Penner, Joyce E.; Atherton, Cynthia S.; Dignon, Jane

1995-07-01

The troposphere is chemically complex. Many of the important species in the troposphere are short-lived, with lifetimes less than or of order of a month. Hence, the composition of the troposphere is regionally diverse, leading to regionally diverse chemical processes which control that composition. With the advent of three-dimensional models and regionally-specific estimates of emissions, however, it has become clear that human activity has perturbed the composition of even short-lived species over vast regions of the globe. The list of short-lived species of concern includes the reactive nitrogen oxides, reactive sulfur, ozone, nonmethane hydrocarbons and carbon monoxide. Observations have established that increases in the long-lived species such as carbon dioxide, methane, nitrous oxide, and the chlorofluorocarbons are taking place with important resulting impacts on stratospheric chemistry. Further, there is some indication that carbonyl sulfide (a major precursor to stratospheric aerosols) may have an important anthropogenic source. Growth of pollutants such as these are of concern because they act as greenhouse gases or aerosol precursors (CO2, CH4, O3, N2O, chlorofluorocarbons, carbonyl sufide, reactive sulfur), as agents for depletion of stratospheric ozone (N2O, chlorofluorocarbons), are harmful to vegetation (O3, acids) or act as nutrients (nitrate, sulfate, trace metals). The chemical interactions are important to understand, because the build up of pollutants depends not only on the rates of their release into the troposphere but on their rate of removal in the troposphere. Removal rates depend on processes which determine the rate of oxidation of the component (which for most species proceeds mainly by reaction with the hydroxyl radical) or through precipitation scavenging or dissolution in the ocean (which requires that the pollutant or its oxidation product(s) be soluble in water).

Highly resolved global distribution of tropospheric NO2 using GOME narrow swath mode data

Directory of Open Access Journals (Sweden)

S. Beirle

2004-01-01

Full Text Available The Global Ozone Monitoring Experiment (GOME allows the retrieval of tropospheric vertical column densities (VCDs of NO2 on a global scale. Regions with enhanced industrial activity can clearly be detected, but the standard spatial resolution of the GOME ground pixels (320x40km2 is insufficient to resolve regional trace gas distributions or individual cities. Every 10 days within the nominal GOME operation, measurements are executed in the so called narrow swath mode with a much better spatial resolution (80x40km2. We use this data (1997-2001 to construct a detailed picture of the mean global tropospheric NO2 distribution. Since - due to the narrow swath - the global coverage of the high resolution observations is rather poor, it has proved to be essential to deseasonalize the single narrow swath mode observations to retrieve adequate mean maps. This is done by using the GOME backscan information. The retrieved high resolution map illustrates the shortcomings of the standard size GOME pixels and reveals an unprecedented wealth of details in the global distribution of tropospheric NO2. Localised spots of enhanced NO2 VCD can be directly associated to cities, heavy industry centers and even large power plants. Thus our result helps to check emission inventories. The small spatial extent of NO2 'hot spots' allows us to estimate an upper limit of the mean lifetime of boundary layer NOx of 17h on a global scale. The long time series of GOME data allows a quantitative comparison of the narrow swath mode data to the nominal resolution. Thus we can analyse the dependency of NO2 VCDs on pixel size. This is important for comparing GOME data to results of new satellite instruments like SCIAMACHY (launched March 2002 on ENVISAT, OMI (launched July 2004 on AURA or GOME II (to be launched 2005 with an improved spatial resolution.

An assessment of 10-year NOAA aircraft-based tropospheric ozone profiling in Colorado

Science.gov (United States)

Leonard, Mark; Petropavlovskikh, Irina; Lin, Meiyun; McClure-Begley, Audra; Johnson, Bryan J.; Oltmans, Samuel J.; Tarasick, David

2017-06-01

The Global Greenhouse Gas Reference Network Aircraft Program at NOAA has sampled ozone and other atmospheric trace constituents in North America for over a decade (2005-present). The method to derive tropospheric ozone climatology from the light aircraft measurements equipped with the 2B Technology instruments is described in this paper. Since ozone instruments at most of aircraft locations are flown once a month, this raises the question of whether the sampling frequency allows for deriving a climatology that can adequately represent ozone seasonal and vertical variability over various locations. Here we interpret the representativeness of the tropospheric ozone climatology derived from these under-sampled observations using hindcast simulations conducted with the Geophysical Fluid Dynamics Laboratory chemistry-climate model (GFDL-AM3). We first focus on ozone measurements from monthly aircraft profiles over the Front Range of Colorado and weekly ozonesondes launched in Boulder, Colorado. The climatology is presented as monthly values separated in 5th, 25th, 50th, 75th, 95th percentiles, and averaged at three vertical layers: lower (1.6-3 km), middle (3-6 km), and upper (6-8 km) troposphere. The aircraft-based climatology is compared to the climatology derived from the nearest located ozonesondes launched from Boulder, Colorado, from GFDL-AM3 co-sampled in time with in-situ observations, and from GFDL-AM3 continuous 3-h samples. Based on these analyses, we recommend the sampling frequency to obtain adequate representation of ozone climatology in the free troposphere. The 3-h sampled AM3 model is used as a benchmark reference for the under-sampled time series. We find that the minimal number of soundings required per month for the all altitude bins (1.6-3, 3-6, and 6-8 km) to sufficiently match the 95% confidence level of the fully sampled monthly ozone means vary between 3 and 5 sounding per month, except in August with a minimum of 6 soundings per month. The

Real-Time Tropospheric Delay Estimation using IGS Products

Science.gov (United States)

Stürze, Andrea; Liu, Sha; Söhne, Wolfgang

2014-05-01

The Federal Agency for Cartography and Geodesy (BKG) routinely provides zenith tropospheric delay (ZTD) parameter for the assimilation in numerical weather models since more than 10 years. Up to now the results flowing into the EUREF Permanent Network (EPN) or E-GVAP (EUMETNET EIG GNSS water vapour programme) analysis are based on batch processing of GPS+GLONASS observations in differential network mode. For the recently started COST Action ES1206 about "Advanced Global Navigation Satellite Systems tropospheric products for monitoring severe weather events and climate" (GNSS4SWEC), however, rapid updates in the analysis of the atmospheric state for nowcasting applications require changing the processing strategy towards real-time. In the RTCM SC104 (Radio Technical Commission for Maritime Services, Special Committee 104) a format combining the advantages of Precise Point Positioning (PPP) and Real-Time Kinematic (RTK) is under development. The so-called State Space Representation approach is defining corrections, which will be transferred in real-time to the user e.g. via NTRIP (Network Transport of RTCM via Internet Protocol). Meanwhile messages for precise orbits, satellite clocks and code biases compatible to the basic PPP mode using IGS products are defined. Consequently, the IGS Real-Time Service (RTS) was launched in 2013 in order to extend the well-known precise orbit and clock products by a real-time component. Further messages e.g. with respect to ionosphere or phase biases are foreseen. Depending on the level of refinement, so different accuracies up to the RTK level shall be reachable. In co-operation of BKG and the Technical University of Darmstadt the real-time software GEMon (GREF EUREF Monitoring) is under development. GEMon is able to process GPS and GLONASS observation and RTS product data streams in PPP mode. Furthermore, several state-of-the-art troposphere models, for example based on numerical weather prediction data, are implemented. Hence, it

Lidar Profiling In the lower Troposphere: experience from PECAN

Science.gov (United States)

Demoz, Belay B.; Delgado, Ruben; Caroll, Brian; Vermeesch, Kevin; Whiteman, David N.; Sakai, Ricardo; Tesfay, Sium; Cooper, Lorenza

2018-04-01

Results from the PECAN (Plains Elevated Convection at Night) campaign are discussed. In particular, the utility of simple backscatter lidars/ceilometers in quantifying atmospheric dynamics parameters and variables as well as evolution of the lower tropospheric dynamics are made. Cases of bore wave dynamics and the potential of these events in lofting of low level, moist, airmass and its consequence in thunderstorm initiation are made. A suite of thermodynamic profiling instruments are combined and compared to describe and visualize lower tropospheric dynamic evolution.

Uncertainties in models of tropospheric ozone based on Monte Carlo analysis: Tropospheric ozone burdens, atmospheric lifetimes and surface distributions

Science.gov (United States)

Derwent, Richard G.; Parrish, David D.; Galbally, Ian E.; Stevenson, David S.; Doherty, Ruth M.; Naik, Vaishali; Young, Paul J.

2018-05-01

Recognising that global tropospheric ozone models have many uncertain input parameters, an attempt has been made to employ Monte Carlo sampling to quantify the uncertainties in model output that arise from global tropospheric ozone precursor emissions and from ozone production and destruction in a global Lagrangian chemistry-transport model. Ninety eight quasi-randomly Monte Carlo sampled model runs were completed and the uncertainties were quantified in tropospheric burdens and lifetimes of ozone, carbon monoxide and methane, together with the surface distribution and seasonal cycle in ozone. The results have shown a satisfactory degree of convergence and provide a first estimate of the likely uncertainties in tropospheric ozone model outputs. There are likely to be diminishing returns in carrying out many more Monte Carlo runs in order to refine further these outputs. Uncertainties due to model formulation were separately addressed using the results from 14 Atmospheric Chemistry Coupled Climate Model Intercomparison Project (ACCMIP) chemistry-climate models. The 95% confidence ranges surrounding the ACCMIP model burdens and lifetimes for ozone, carbon monoxide and methane were somewhat smaller than for the Monte Carlo estimates. This reflected the situation where the ACCMIP models used harmonised emissions data and differed only in their meteorological data and model formulations whereas a conscious effort was made to describe the uncertainties in the ozone precursor emissions and in the kinetic and photochemical data in the Monte Carlo runs. Attention was focussed on the model predictions of the ozone seasonal cycles at three marine boundary layer stations: Mace Head, Ireland, Trinidad Head, California and Cape Grim, Tasmania. Despite comprehensively addressing the uncertainties due to global emissions and ozone sources and sinks, none of the Monte Carlo runs were able to generate seasonal cycles that matched the observations at all three MBL stations. Although

Tropospheric effects of energy conversion

International Nuclear Information System (INIS)

Derwent, R.G.

1992-01-01

The tropospheric concentrations of a number of trace gases are increasing due to man's activities. For some trace gases, their atmospheric life cycles are not fully understood and it is difficult to be certain about the role of man's activities. Emissions from the energy industries and energy conversion processes represent an important subset of source terms in these life cycles, along with agriculture, deforestation, cement manufacture, biomass burning, process industries and natural biospheric processes. Global Warming Potentials (GWPs) allow the tropospheric effects of a range of climate forcing trace gases to be assessed on a comparable basis. If a short term view of the commitment to global warming is adopted then the contribution from other trace gases may approach and exceed that of carbon dioxide, itself. Over longer time horizons, the long atmospheric lifetime of carbon dioxide shows through as a major influence and the contributions from the other trace gases appear to be much smaller, representing an additional 13-18% contribution on top of that from CO 2 itself

Comparisons of the tropospheric specific humidity from GPS radio occultations with ERA-Interim, NASA MERRA, and AIRS data

Science.gov (United States)

Vergados, Panagiotis; Mannucci, Anthony J.; Ao, Chi O.; Verkhoglyadova, Olga; Iijima, Byron

2018-03-01

We construct a 9-year data record (2007-2015) of the tropospheric specific humidity using Global Positioning System radio occultation (GPS RO) observations from the Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) mission. This record covers the ±40° latitude belt and includes estimates of the zonally averaged monthly mean specific humidity from 700 up to 400 hPa. It includes three major climate zones: (a) the deep tropics (±15°), (b) the trade winds belts (±15-30°), and (c) the subtropics (±30-40°). We find that the RO observations agree very well with the European Centre for Medium-Range Weather Forecasts Re-Analysis Interim (ERA-Interim), the Modern-Era Retrospective Analysis for Research and Applications (MERRA), and the Atmospheric Infrared Sounder (AIRS) by capturing similar magnitudes and patterns of variability in the monthly zonal mean specific humidity and interannual anomaly over annual and interannual timescales. The JPL and UCAR specific humidity climatologies differ by less than 15 % (depending on location and pressure level), primarily due to differences in the retrieved refractivity. In the middle-to-upper troposphere, in all climate zones, JPL is the wettest of all data sets, AIRS is the driest of all data sets, and UCAR, ERA-Interim, and MERRA are in very good agreement, lying between the JPL and AIRS climatologies. In the lower-to-middle troposphere, we present a complex behavior of discrepancies, and we speculate that this might be due to convection and entrainment. Conclusively, the RO observations could potentially be used as a climate variable, but more thorough analysis is required to assess the structural uncertainty between centers and its origin.

Verification and Validation of Tropospheric Model/Database

National Research Council Canada - National Science Library

Junho, choi

1998-01-01

A verification and validation of tropospheric models and databases has been performed based on ray tracing algorithm, statistical analysis, test on real time system operation, and other technical evaluation process...

Tropospheric Emissions: Monitoring of Pollution Overview

Science.gov (United States)

Chance, Kelly; Liu, Xiong; Suleiman, Raid M.; Flittner, David; Al-Saadi, Jay; Janz, Scott

2015-01-01

TEMPO is now well into its implementation phase, having passed both its Key Decision Point C and the Critical Design Review (CDR) for the instrument. The CDR for the ground systems will occur in March 2016 and the CDR for the Mission component at a later date, after the host spacecraft has been selected. TEMPO is on schedule to measure atmospheric pollution for greater North America from space using ultraviolet and visible spectroscopy. TEMPO measures from Mexico City to the Canadian oil sands, and from the Atlantic to the Pacific, hourly and at high spatial resolution. TEMPO provides a tropospheric measurement suite that includes the key elements of tropospheric air pollution chemistry. Measurements are from geostationary (GEO) orbit, to capture the inherent high variability in the diurnal cycle of emissions and chemistry. The small product spatial footprint resolves pollution sources at sub-urban scale. Together, this temporal and spatial resolution improves emission inventories, monitors population exposure, and enables effective emission-control strategies. TEMPO takes advantage of a GEO host spacecraft to provide a modest cost mission that measures the spectra required to retrieve O3, NO2, SO2, H2CO, C2H2O2, H2O, aerosols, cloud parameters, and UVB radiation. TEMPO thus measures the major elements, directly or by proxy, in the tropospheric O3 chemistry cycle. Multi-spectral observations provide sensitivity to O3 in the lowermost troposphere, substantially reducing uncertainty in air quality predictions by 50 percent. TEMPO quantifies and tracks the evolution of aerosol loading. It provides near-real-time air quality products that will be made widely, publicly available. TEMPO provides much of the atmospheric measurement capability recommended for GEO-CAPE in the 2007 National Research Council Decadal Survey, Earth Science and Applications from Space: National Imperatives for the Next Decade and Beyond. Instruments from Europe (Sentinel 4) and Asia (GEMS) will

Tropospheric ozone over Equatorial Africa: regional aspects from the MOZAIC data

Directory of Open Access Journals (Sweden)

B. Sauvage

2005-01-01

Full Text Available We analyze ozone observations recorded over Equatorial Africa between April 1997 and March 2003 by the MOZAIC programme, providing the first ozone climatology deriving from continental in-situ data over this region. Three-dimensional streamlines strongly suggests connections between the characteristics of the ozone monthly mean vertical profiles, the most persistent circulation patterns in the troposphere over Equatorial Africa (on a monthly basis such as the Harmattan, the African Easterly Jet, the Trades and the regions of ozone precursors emissions by biomass burning. During the biomass burning season in each hemisphere, the lower troposphere exhibits layers of enhanced ozone (i.e. 70 ppbv over the coast of Gulf of Guinea in December-February and 85 ppbv over Congo in June-August. The characteristics of the ozone monthly mean vertical profiles are clearly connected to the regional flow regime determined by seasonal dynamic forcing. The mean ozone profile over the coast of Gulf of Guinea in the burning season is characterized by systematically high ozone below 650hPa ; these are due to the transport by the Harmattan and the AEJ of the pollutants originating from upwind fires. The confinement of high ozone to the lower troposphere is due to the high stability of the Harmattan and the blocking Saharan anticyclone which prevents efficient vertical mixing. In contrast, ozone enhancements observed over Central Africa during the local dry season (June-August are not only found in the lower troposphere but throughout the troposphere. Moreover, this study highlights a connection between the regions of the coast of Gulf of Guinea and regions of Congo to the south that appears on a semi annual basis. Vertical profiles in wet-season regions exhibit ozone enhancements in the lower troposphere due to biomass burning products transport from fires situated in the opposite dry-season hemisphere.

An Assessment of Ground Level and Free Tropospheric Ozone Over California and Nevada

Science.gov (United States)

Yates, E. L.; Johnson, M. S.; Iraci, L. T.; Ryoo, J.-M.; Pierce, R. B.; Cullis, P. D.; Gore, W.; Ives, M. A.; Johnson, B. J.; Leblanc, T.; Marrero, J. E.; Sterling, C. W.; Tanaka, T.

2017-09-01

Increasing free tropospheric ozone (O3), combined with the high elevation and often deep boundary layers at western U.S. surface stations, poses challenges in attaining the more stringent 70 ppb O3 National Ambient Air Quality Standard. As such, use of observational data to identify sources and mechanisms that contribute to surface O3 is increasingly important. This work analyzes surface and vertical O3 observations over California and Nevada from 1995 to 2015. Over this period, the number of high O3 events (95th percentile) at the U.S. Environmental Protection Agency Clean Air Status and Trends Network (CASTNET) sites has decreased during summer, as a result of decreasing U.S. emissions. In contrast, an increase in springtime 5th percentile O3 indicates a general increase of baseline O3. During 2012 there was a peak in exceedances and in the average spring-summer O3 mixing ratios at CASTNET sites. Goddard Earth Observing System-Chem results show that the surface O3 attributable to transport from the upper troposphere and stratosphere was increased in 2013 compared to 2012, highlighting the importance of measurements aloft. Vertical O3 measurements from aircraft, ozonesondes, and lidar show distinct seasonal trends, with a high percentage of elevated O3 laminae (O3 > 70 ppb, 3-8 km) during spring and summer. Analysis of the timing of high O3 surface events and correlation between surface and vertical O3 data is used to discuss varying sources of western U.S. surface O3.

Derivation of Tropospheric Ozone Climatology and Trends from TOMS Data

Science.gov (United States)

Newchurch, Michael J.; McPeters, Rich; Logan, Jennifer; Kim, Jae-Hwan

2002-01-01

This research addresses the following three objectives: (1) Derive tropospheric ozone columns from the TOMS instruments by computing the difference between total-ozone columns over cloudy areas and over clear areas in the tropics; (2) Compute secular trends in Nimbus-7 derived tropospheric Ozone column amounts and associated potential trends in the decadal-scale tropical cloud climatology; (3) Explain the occurrence of anomalously high ozone retrievals over high ice clouds.

A joint data record of tropospheric ozone from Aura-TES and MetOp-IASI

Directory of Open Access Journals (Sweden)

H. Oetjen

2016-08-01

Full Text Available The Tropospheric Emission Spectrometer (TES on Aura and Infrared Atmospheric Sounding Interferometer (IASI on MetOp-A together provide a time series of 10 years of free-tropospheric ozone with an overlap of 3 years. We characterise the differences between TES and IASI ozone measurements and find that IASI's coarser vertical sensitivity leads to a small (< 5 ppb low bias relative to TES for the free troposphere. The TES-IASI differences are not dependent on season or any other factor and hence the measurements from the two instruments can be merged, after correcting for the offset, in order to study decadal-scale changes in tropospheric ozone. We calculate time series of regional monthly mean ozone in the free troposphere over eastern Asia, the western United States (US, and Europe, carefully accounting for differences in spatial sampling between the instruments. We show that free-tropospheric ozone over Europe and the western US has remained relatively constant over the past decade but that, contrary to expectations, ozone over Asia in recent years does not continue the rapid rate of increase observed from 2004 to 2010.

THE METHOD FOR IDENTIFYING THE MOST VULNERABLE AREAS CAUSED BY EXOGENOUS PROCESSES UNDER ARIDIFICATION/HUMIDIFICATION (BASED ON GIS AND RS

Directory of Open Access Journals (Sweden)

D. A. Chupina

2017-01-01

Full Text Available The paper presents the method of identifying the most vulnerable territories under exogenous processes caused by aridification/humidification. It is based on the assumption that some forms and types of relief increase resistance of terrestrial ecosystems to external influences, while other kinds of relief make them vulnerable. The relationship between landscape and moistening (ground and climatic is of great importance to plains which have groundwater close to the surface. We have used morphometric analysis to divide the territory into hydromorphic and automorphic landscapes. Hydromorphic territories are those that are affected by additional surface moistening and groundwater, while automorphic landscapes are less dependent on groundwater under normal atmospheric moisture. The territory is ranked according to the degree of vulnerability by expert evaluation method. The developed approach is based entirely on using GIS software (ArcGIS 10.2.1 and processing the DEM SRTM. As a result, two models of vulnerability of natural terrestrial ecosystems to exogenic processes on Baraba Plain (Western Siberia have been created for both aridification and humidification cases. The opportunity to estimate the vulnerability is the novel feature for these models of terrestrial ecosystems, in both regional and local scales. The results obtained confirm the existing ideas about the discrete mosaic character of changes in spatial landscape patterns in the area under consideration. For the southern part of Western Siberia where farming is risky the assessment of the potential degree of vulnerability for ecosystems under conditions of increasing climate aridity and extremes is relevant.

Influence of corona discharge on the ozone budget in the tropical free troposphere: a case study of deep convection during GABRIEL

Science.gov (United States)

Bozem, H.; Fischer, H.; Gurk, C.; Schiller, C. L.; Parchatka, U.; Koenigstedt, R.; Stickler, A.; Martinez, M.; Harder, H.; Kubistin, D.; Williams, J.; Eerdekens, G.; Lelieveld, J.

2014-02-01

Convective redistribution of ozone and its precursors between the boundary layer (BL) and the free troposphere (FT) influences photochemistry, in particular that of the middle and upper troposphere (UT). We present a case study of convective transport during the GABRIEL campaign over the tropical rain forest in Suriname in October 2005. During a measurement flight on 12 October the inflow and outflow regions of a cumulonimbus cloud (Cb) have been characterized, providing evidence of convective transport. We identified a distinct layer between 9 and 11 km altitude with enhanced mixing ratios of CO, O3, HOx, acetone and acetonitrile. The elevated O3 contradicts the expectation that convective transport brings low ozone air from the boundary layer to the outflow region. The enhanced mixing ratio of ozone in the outflow was mainly of dynamical origin. Entrainment of ozone rich air at the outflow level into the convective outflow accounts for 62% (range: 33-91%) of the observed O3. Ozone is enhanced by only 5-6% by photochemical production in the outflow due to enhanced NO from lightning, based on steady state model calculations, using in-situ observations including the first reported HOx measurements over the tropical rainforest. The "excess" ozone in the outflow is most probably due to direct production by corona discharge associated with lightning. We deduce a production rate of 5.12 × 1028 molecules O3 flash-1 (range: 9.89 × 1026-9.82 × 1028 molecules O3 flash-1), which is at the upper limit of the range of the values reported previously.

Lidar Profiling In the lower Troposphere: experience from PECAN

Directory of Open Access Journals (Sweden)

Demoz Belay B.

2018-01-01

Full Text Available Results from the PECAN (Plains Elevated Convection at Night campaign are discussed. In particular, the utility of simple backscatter lidars/ceilometers in quantifying atmospheric dynamics parameters and variables as well as evolution of the lower tropospheric dynamics are made. Cases of bore wave dynamics and the potential of these events in lofting of low level, moist, airmass and its consequence in thunderstorm initiation are made. A suite of thermodynamic profiling instruments are combined and compared to describe and visualize lower tropospheric dynamic evolution.

Carbon monoxide and methane in the North American Arctic and Subarctic troposphere - July-August 1988

Energy Technology Data Exchange (ETDEWEB)

Harriss, R.C.; Sachse, G.W.; Hill, G.F.; Wade, L.; Bartlett, K.B.; Collins, J.E.; Steele, L.P.; Novelli, P.C. (New Hampshire Univ., Durham (United States) NASA, Langley Research Center, Hampton, VA (United States) Lockheed Engineering Sciences Co., Hampton, VA (United States) Science and Technology Corp., Hampton, VA (United States) Cooperative Inst. for Research in Environmental Sciences, Boulder, CO (United States))

1992-10-01

Enhanced concentrations of CH4 in the unpolluted atmospheric mixed layer over both Arctic and subarctic tundra landscapes are documented here using data from the NASA Arctic Boundary Layer Expedition (ABLE 3A). The CH4 concentration gradients were determined mainly by interactions of biogenic emission from wet tundra and turbulent mixing proceses. The gradient were most frequently associated with intrusion of upper tropospheric or stratospheric air into the midtroposphere, emissions from forest and tundra fires, and long-range transport of enhanced concentration of these gases from unidentified sources. Summertime haze layers exhibited midtropospheric enhancements of CH4 similar to those measured in winter Arctic events. The observations confirm the importance of Arctic and Subarctic wetland environments as a regional source of global atmospheric CH4. 33 refs.

Impact of West African Monsoon convective transport and lightning NOx production upon the upper tropospheric composition: a multi-model study

Directory of Open Access Journals (Sweden)

H. Schlager

2010-06-01

Full Text Available Within the African Monsoon Multidisciplinary Analysis (AMMA, we investigate the impact of nitrogen oxides produced by lightning (LiNOx and convective transport during the West African Monsoon (WAM upon the composition of the upper troposphere (UT in the tropics. For this purpose, we have performed simulations with 4 state-of-the-art chemistry transport models involved within AMMA, namely MOCAGE, TM4, LMDz-INCA and p-TOMCAT. The model intercomparison is complemented with an evaluation of the simulations based on both spaceborne and airborne observations. The baseline simulations show important differences between the UT CO and O3 distributions simulated by each of the 4 models when compared to measurements from the MOZAIC program and fom the Aura/MLS spaceborne sensor. We show that such model discrepancies can be explained by differences in the convective transport parameterizations and, more particularly, the altitude reached by convective updrafts (ranging between ~200–125 hPa. Concerning UT O3, the models exhibit a good agreement with the main observed features. Nevertheless the majority of models simulate low O3 concentrations compared to both MOZAIC and Aura/MLS observations south of the equator, and rather high concentrations in the Northern Hemisphere. Sensitivity studies are performed to quantify the effect of deep convective transport and the influence of LiNOx production on the UT composition. These clearly indicate that the CO maxima and the elevated O3 concentrations south of the equator are due to convective uplift of air masses impacted by Southern African biomass burning, in agreement with previous studies. Moreover, during the WAM, LiNOx from Africa are responsible for the highest UT O3 enhancements (10–20 ppbv over the tropical Atlantic between 10° S–20° N. Differences between models are primarily due to the performance of the parameterizations used to simulate lightning activity which are evaluated using spaceborne

Experimental investigation of a multi-stage humidification-dehumidification desalination system heated directly by a cylindrical Fresnel lens solar concentrator

International Nuclear Information System (INIS)

Wu, Gang; Zheng, Hongfei; Ma, Xinglong; Kutlu, Cagri; Su, Yuehong

2017-01-01

Highlights: • A solar desalination system heated directly by curved Fresnel lens concentrator. • Desalination system is based on the humidification-dehumidification process. • Four-stage multi-effect desalination system is proposed. • Condensation latent heat and residual heat in the brine are recycled and reutilized. • The maximum yield and GOR of the unit can reach 3.4 kg/h and 2.1, respectively. - Abstract: This study demonstrates a multi-stage humidification-dehumidification (HDH) solar desalination system heated directly by a cylindrical Fresnel lens concentrator. In this novel system, the solar radiation is sent directly into desalination unit. That is to say, the solar receiver and the evaporator of the system are a whole in which the black fillers in seawater directly absorb the concentrated solar lights to heat the seawater film to produce the evaporation. The configuration and working processes of the proposed design are described in detail. In order to analyze its performance, a small solar desalination prototype unit incorporated with a cylindrical Fresnel lens concentrator was designed and built in our laboratory. Using three-stage isothermal tandem heating mode, the variation of the fresh water yield rate and the absorber temperature with time were measured experimentally and were compared with theoretical calculations. The experimental results show that the maximum yield of the unit is about 3.4 kg/h, the maximum gained output ratio (GOR) is about 2.1, when the average intensity of solar radiation is about 867 W/m"2. This study indicates that the proposed system has the characteristics of compact structure and GOR high. It still can be improved when the design and operation are optimized further.

Where should the upper boundary of the earth's critical zone be?

Science.gov (United States)

Liu, W.; Zhang, X. J.

2017-12-01

Recently increasing attention has been paid to the study of the critical zone (CZ) of the earth. The upper boundary of the CZ is generally defined as the top of plant canopy, and the lower boundary at the bottom of deep groundwater. The question is whether the ecological, biogeochemical and hydrological processes that are the focuses of CZ research occur within the scope of such boundaries. The role of water is central in these processes as is shown by the current studies as follows. First, there exist water vapor transport strips or pathways with higher flux strength than the surrounding areas in the troposphere, known as "tropospheric rivers" or "atmospheric rivers" (Newell, et al, 1992; Zhu, et al, 1998), specially dubbed as "sky rivers" (Wang, et al, 2016). The sky rivers are connected with the surface and underground rivers by precipitation and evapotranspiration processes, forming a complete water cycle system of the earth. Second, changes in atmospheric composition, such as aerosol increases, the formation of smog, CO2 concentration rising, directly or indirectly affected solar radiation and plant growth, which to a large extent determine potential evapotranspiration and vegetation cover change. Based on the Budyko model, annual water balance at a catchment is closely related to these changes (Zhang, et al., 2001; Ning, et al., 2017). Third, the theory of evaporation complementarity holds that surface evapotranspiration can be completely determined and calculated by meteorological data. Based on the eddy covariance observation for water and heat flux in the Loess Plateau (Brutsaert, et al., 2017), the relationship between calculated and observed ET values becomes stronger from 2m to 32m, which may be related to the existence of a blending height at higher elevations above the ground. Therefore, we deem that the CZ upper boundary should be selected at the tropopause of the atmosphere. The troposphere, directly affected by the earth surface, contains 3/4 of

The Tropospheric Products of the International VLBI Service for Geodesy and Astrometry

Science.gov (United States)

Heinkelmann, Robert; Schwatke, Christian

2010-01-01

The IVS runs two tropospheric products: The IVS tropospheric parameter rapid combination monitors the zenith wet delay (ZWD) and zenith total delay (ZTD) of the rapid turnaround sessions R1 and R4. Goal of the combination is the identification and the exclusion of outliers by comparison and the assessment of the precision of current VLBI solutions in terms of tropospheric parameters. The rapid combination is done on a weekly basis four weeks after the observation files are released on IVS Data Centers. Since tropospheric and geodetic parameters, such as vertical station components, can significantly correlate, the consistency of the ZTD can be a measure of the consistency of the corresponding TRF as well. The ZWD mainly rely on accurate atmospheric pressure data. Thus, besides estimation techniques, modeling and analyst s noise, ZWD reflects differences in the atmospheric pressure data applied to the VLBI analysis. The second product, called tropospheric parameter long-term combination, aims for an accurate determination of climatological signals, such as trends of the atmospheric water vapor observed by VLBI. Therefore, the long-term homogeneity of atmospheric pressure data plays a crucial role for this product. The paper reviews the methods applied and results achieved so far and describes the new maintenance through DGFI.

Seasonal variations and vertical features of aerosol particles in the Antarctic troposphere

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Keiichiro Hara

2010-12-01

Full Text Available Tethered balloon-borne aerosol measurements were carried out at Syowa Station, Antarctica during the 46th Japanese Antarctic Research Expedition. CN concentration had a maximum in the summer, whereas the number concentrations of fine particles (D_p>0.3 μm and coarse particles (D_p>2.0 μm increased during the winter-spring. The range of CN concentration was 30-2200 cm^ near the surface (surface-500 m and 7-7250 cm^ in the lower free troposphere (>1500 m. During the austral summer, higher CN concentration was often observed in the lower free troposphere. Frequent appearance of higher CN concentration in the free troposphere relative to the surface measurements strongly suggests that new particle formation in the Antarctic regions occurs in the lower free troposphere. Single particle analysis indicated that most of the aerosol particles during the winter were composed of Mg-enriched sea-salt particles originated from sea-salt fractionation on the sea-ice and their modified particles by NO_3^ and SO_4^. This suggests that sea-salt fractionation on sea-ice and modification of sea-salt particles were affected greatly by aerosol hygroscopicity during the winter. Antarctic haze layer was observed not only in the boundary layer but also in the lower free troposphere.

Greenhouse Observations of the Stratosphere and Troposphere (GHOST): a novel shortwave infrared spectrometer developed for the Global Hawk unmanned aerial vehicle

Science.gov (United States)

Humpage, Neil; Boesch, Hartmut; Palmer, Paul; Parr-Burman, Phil; Vick, Andy; Bezawada, Naidu; Black, Martin; Born, Andy; Pearson, David; Strachan, Jonathan; Wells, Martyn

2014-05-01

The tropospheric distribution of greenhouse gases (GHGs) is dependent on surface flux variations, atmospheric chemistry and transport processes over a wide range of spatial and temporal scales. Errors in assumed atmospheric transport can adversely affect surface flux estimates inferred from surface, aircraft or satellite observations of greenhouse gas concentrations using inverse models. We present a novel, compact shortwave infrared spectrometer (GHOST) for installation on the NASA Global Hawk unmanned aerial vehicle to provide tropospheric column observations of CO2, CO, CH4, H2O and HDO over the ocean to address the need for large-scale, simultaneous, finely resolved measurements of key GHGs. These species cover a range of lifetimes and source processes, and measurements of their tropospheric columns will reflect the vertically integrated signal of their vertical and horizontal transport within the troposphere. The primary science objectives of GHOST are to: 1) provide observations which can be used to test atmospheric transport models; 2) validate satellite observations of GHG column observations over oceans, thus filling a critical gap in current validation capabilities; and 3) complement in-situ tropopause transition layer tracer observations from other instrumentation on board the Global Hawk to provide a link between upper and lower troposphere concentration measurements. The GHOST spectrometer system comprises a target acquisition module (TAM), a fibre slicer and feed system, and a multiple order spectrograph. The TAM design utilises a gimbal behind an optical dome, which is programmed to direct solar radiation reflected by the ocean surface into a fibre optic bundle. The fibre slicer and feed system then splits the light into the four spectral bands using order sorting filters. The fibres corresponding to each band are arranged with a small sideways offset to correctly centre each spectrum on the detector array. The spectrograph design is unique in that a

How Can TOLNet Help to Better Understand Tropospheric Ozone? A Satellite Perspective

Science.gov (United States)

Johnson, Matthew S.

2018-01-01

Potential sources of a priori ozone (O3) profiles for use in Tropospheric Emissions: Monitoring of Pollution (TEMPO) satellite tropospheric O3 retrievals are evaluated with observations from multiple Tropospheric Ozone Lidar Network (TOLNet) systems in North America. An O3 profile climatology (tropopause-based O3 climatology (TB-Clim), currently proposed for use in the TEMPO O3 retrieval algorithm) derived from ozonesonde observations and O3 profiles from three separate models (operational Goddard Earth Observing System (GEOS-5) Forward Processing (FP) product, reanalysis product from Modern-Era Retrospective analysis for Research and Applications version 2 (MERRA2), and the GEOS-Chem chemical transport model (CTM)) were: 1) evaluated with TOLNet measurements on various temporal scales (seasonally, daily, hourly) and 2) implemented as a priori information in theoretical TEMPO tropospheric O3 retrievals in order to determine how each a priori impacts the accuracy of retrieved tropospheric (0-10 km) and lowermost tropospheric (LMT, 0-2 km) O3 columns. We found that all sources of a priori O3 profiles evaluated in this study generally reproduced the vertical structure of summer-averaged observations. However, larger differences between the a priori profiles and lidar observations were observed when evaluating inter-daily and diurnal variability of tropospheric O3. The TB-Clim O3 profile climatology was unable to replicate observed inter-daily and diurnal variability of O3 while model products, in particular GEOS-Chem simulations, displayed more skill in reproducing these features. Due to the ability of models, primarily the CTM used in this study, on average to capture the inter-daily and diurnal variability of tropospheric and LMT O3 columns, using a priori profiles from CTM simulations resulted in TEMPO retrievals with the best statistical comparison with lidar observations. Furthermore, important from an air quality perspective, when high LMT O3 values were

Transportable lidar for the measurement of ozone concentration and flux profiles in the lower troposphere

International Nuclear Information System (INIS)

Zhao, Yanzeng; Howell, J.N.; Hardesty, R.M.

1992-01-01

In many areas of the United States, as well as in other industrial areas (such as Europe), elevated and potentially harmful levels of ozone are being measured during summer. Most of this ozone is photochemically produced. The relatively long lifetime of ozone allows industrially produced ozone to be transported on a hemispheric scale. Since the trends of tropospheric ozone are very likely dependent on the source strengths and distributions of the pollutants and the chemical/ transport process involved, a predictive understanding of tropospheric ozone climatology requires a focus on the chemical and transport processes that link regional emissions to hemispheric ozone trends and distributions. Of critical importance to these studies is a satisfactory data base of tropospheric ozone distribution from which global and regional tropospheric ozone climatology can be derived, and the processes controlling tropospheric ozone can be better understood. A transportable lidar for measuring ozone concentration and flux profiles in the lower troposphere is needed. One such system is being developed at the National Oceanic and Atmospheric Administration/Earth Resources Laboratory (NOAA/ERL) Wave Propagation Laboratory (WPL)

VLBI-derived troposphere parameters during CONT08

Science.gov (United States)

Heinkelmann, R.; Böhm, J.; Bolotin, S.; Engelhardt, G.; Haas, R.; Lanotte, R.; MacMillan, D. S.; Negusini, M.; Skurikhina, E.; Titov, O.; Schuh, H.

2011-07-01

Time-series of zenith wet and total troposphere delays as well as north and east gradients are compared, and zenith total delays ( ZTD) are combined on the level of parameter estimates. Input data sets are provided by ten Analysis Centers (ACs) of the International VLBI Service for Geodesy and Astrometry (IVS) for the CONT08 campaign (12-26 August 2008). The inconsistent usage of meteorological data and models, such as mapping functions, causes systematics among the ACs, and differing parameterizations and constraints add noise to the troposphere parameter estimates. The empirical standard deviation of ZTD among the ACs with regard to an unweighted mean is 4.6 mm. The ratio of the analysis noise to the observation noise assessed by the operator/software impact (OSI) model is about 2.5. These and other effects have to be accounted for to improve the intra-technique combination of VLBI-derived troposphere parameters. While the largest systematics caused by inconsistent usage of meteorological data can be avoided and the application of different mapping functions can be considered by applying empirical corrections, the noise has to be modeled in the stochastic model of intra-technique combination. The application of different stochastic models shows no significant effects on the combined parameters but results in different mean formal errors: the mean formal errors of the combined ZTD are 2.3 mm (unweighted), 4.4 mm (diagonal), 8.6 mm [variance component (VC) estimation], and 8.6 mm (operator/software impact, OSI). On the one hand, the OSI model, i.e. the inclusion of off-diagonal elements in the cofactor-matrix, considers the reapplication of observations yielding a factor of about two for mean formal errors as compared to the diagonal approach. On the other hand, the combination based on VC estimation shows large differences among the VCs and exhibits a comparable scaling of formal errors. Thus, for the combination of troposphere parameters a combination of the two

Solar desalination using humidification-dehumidification processes. Part II. An experimental investigation

International Nuclear Information System (INIS)

Nafey, A.S.; Fath, H.E.S.; El-Helaby, S.O.; Soliman, A.

2004-01-01

An experimental investigation of a humidification-dehumidification desalination (HDD) process using solar energy at the weather conditions of Suez City, Egypt, is presented. A test rig is designed and constructed to conduct this investigation under different environmental and operating conditions. The test rig consists of a solar water heater (concentrator solar collector type), solar air heater (flat plate solar collector type), humidifier tower and dehumidifier exchanger. Different variables are examined including the feed water flow rate, the air flow rate, the cooling water flow rate in the dehumidifier and the weather conditions. Comparisons between the experimental results and other published results are presented. It is found that the results of the developed mathematical model by the same authors are in good agreement with the experimental results. The tested results show that the productivity of the system is strongly affected by the saline water temperature at the inlet to the humidifier, dehumidifier cooling water flow rate, air flow rate and solar intensity. The wind speed and ambient temperature variation were found to have a very small effect on the system productivity. A general correlation is developed to predict the unit productivity under different operating conditions. The results of this correlation have a reasonable confidence level (maximum error ±6%)

Software for Generating Troposphere Corrections for InSAR Using GPS and Weather Model Data

Science.gov (United States)

Moore, Angelyn W.; Webb, Frank H.; Fishbein, Evan F.; Fielding, Eric J.; Owen, Susan E.; Granger, Stephanie L.; Bjoerndahl, Fredrik; Loefgren, Johan; Fang, Peng; Means, James D.;

Mathematical model for solar-hydrogen heated desalination plant using humidification-dehumidification process

International Nuclear Information System (INIS)

Yassin, Jamal S.; Eljrushi, Gibril S.

2006-01-01

This paper presents a mathematical model for thermal desalination plant operating with solar energy and hydrogen. This plant is composed of two main systems, the heating system and the distillation system. The distillation system is composed of multi-cells; each cell is using the humidification-dehumidification (H-D) process in the distillation unit and getting the required amount of heat from feed seawater heater. The feed seawater heater is a heat exchanger used to raise the temperature of the preheated seawater coming from the condensation chamber (Dehumidifier) of each cell to about 85 degree centigrade. The heating amount in the heat exchangers is obtained from the thermal storage tank, which gets its energy from solar thermal system and is coupled with a hydrogen-fired backup system to guaranty necessary operating conditions and permit 24 hours solar H-D desalination plant to enhance the performance of this system. The mathematical model studies the performance of the proposed desalination system using thermal solar energy and hydrogen as fuel. Other pertinent variable in the heating and distillation system are also studied. The outcomes of this study are analyzed to enhance the used solar desalination process and make commercial.(Author)

Effects of the 2004 El Nino on tropospheric ozone and water vapor

NARCIS (Netherlands)

Chandra, S.; Ziemke, J.R.; Schoeberl, M.R.; Froidevaux, L.; Read, W.G.; Levelt, P.F.; Bhartia, P.K.

2007-01-01

The global effects of the 2004 El Nino on tropospheric ozone and H/sub 2/O based on Aura OMI and MLS measurements are analyzed. Although it was a weak El Nino from a historical perspective, it produced significant changes in these parameters in tropical latitudes. Tropospheric ozone increased by

Global observations of tropospheric BrO columns using GOME-2 satellite data

Science.gov (United States)

Theys, N.; van Roozendael, M.; Hendrick, F.; Yang, X.; de Smedt, I.; Richter, A.; Begoin, M.; Errera, Q.; Johnston, P. V.; Kreher, K.; de Mazière, M.

2011-02-01

Measurements from the GOME-2 satellite instrument have been analyzed for tropospheric BrO using a residual technique that combines measured BrO columns and estimates of the stratospheric BrO content from a climatological approach driven by O3 and NO2 observations. Comparisons between the GOME-2 results and BrO vertical columns derived from correlative ground-based and SCIAMACHY nadir observations, present a good level of consistency. We show that the adopted technique enables separation of stratospheric and tropospheric fractions of the measured total BrO columns and allows quantitative study of the BrO plumes in polar regions. While some satellite observed plumes of enhanced BrO can be explained by stratospheric descending air, we show that most BrO hotspots are of tropospheric origin, although they are often associated to regions with low tropopause heights as well. Elaborating on simulations using the p-TOMCAT tropospheric chemical transport model, this result is found to be consistent with the mechanism of bromine release through sea salt aerosols production during blowing snow events. No definitive conclusion can be drawn however on the importance of blowing snow sources in comparison to other bromine release mechanisms. Outside polar regions, evidence is provided for a global tropospheric BrO background with column of 1-3 × 1013 molec cm-2, consistent with previous estimates.

Tropospheric ozone trend over Beijing from 2002–2010: ozonesonde measurements and modeling analysis

OpenAIRE

Y. Wang; P. Konopka; Y. Liu; H. Chen; R. Müller; F. Plöger; M. Riese; Z. Cai; D. Lü

2012-01-01

Using a combination of ozonesonde data and numerical simulations of the Chemical Lagrangian Model of the Stratosphere (CLaMS), the trend of tropospheric ozone (O₃) during 2002–2010 over Beijing was investigated. Tropospheric ozone over Beijing shows a winter minimum and a broad summer maximum with a clear positive trend in the maximum summer ozone concentration over the last decade. The observed significant trend of tropospheric column ozone is mainly caused by photoche...

Tropospheric products of the second GOP European GNSS reprocessing (1996-2014)

Science.gov (United States)

Dousa, Jan; Vaclavovic, Pavel; Elias, Michal

2017-09-01

In this paper, we present results of the second reprocessing of all data from 1996 to 2014 from all stations in International Association of Geodesy (IAG) Reference Frame Sub-Commission for Europe (EUREF) Permanent Network (EPN) as performed at the Geodetic Observatory Pecný (GOP). While the original goal of this research was to ultimately contribute to the realization of a new European Terrestrial Reference System (ETRS), we also aim to provide a new set of GNSS (Global Navigation Satellite System) tropospheric parameter time series with possible applications to climate research. To achieve these goals, we improved a strategy to guarantee the continuity of these tropospheric parameters and we prepared several variants of troposphere modelling. We then assessed all solutions in terms of the repeatability of coordinates as an internal evaluation of applied models and strategies and in terms of zenith tropospheric delays (ZTDs) and horizontal gradients with those of the ERA-Interim numerical weather model (NWM) reanalysis. When compared to the GOP Repro1 (first EUREF reprocessing) solution, the results of the GOP Repro2 (second EUREF reprocessing) yielded improvements of approximately 50 and 25 % in the repeatability of the horizontal and vertical components, respectively, and of approximately 9 % in tropospheric parameters. Vertical repeatability was reduced from 4.14 to 3.73 mm when using the VMF1 mapping function, a priori ZHD (zenith hydrostatic delay), and non-tidal atmospheric loading corrections from actual weather data. Raising the elevation cut-off angle from 3 to 7° and then to 10° increased RMS from coordinates' repeatability, which was then confirmed by independently comparing GNSS tropospheric parameters with the NWM reanalysis. The assessment of tropospheric horizontal gradients with respect to the ERA-Interim revealed a strong sensitivity of estimated gradients to the quality of GNSS antenna tracking performance. This impact was demonstrated at the

Impact of climate change on tropospheric ozone and its global budgets

Directory of Open Access Journals (Sweden)

G. Zeng

2008-01-01

Full Text Available We present the chemistry-climate model UM_CAM in which a relatively detailed tropospheric chemical module has been incorporated into the UK Met Office's Unified Model version 4.5. We obtain good agreements between the modelled ozone/nitrogen species and a range of observations including surface ozone measurements, ozone sonde data, and some aircraft campaigns.

Four 2100 calculations assess model responses to projected changes of anthropogenic emissions (SRES A2, climate change (due to doubling CO₂, and idealised climate change-associated changes in biogenic emissions (i.e. 50% increase of isoprene emission and doubling emissions of soil-NO_x. The global tropospheric ozone burden increases significantly for all the 2100 A2 simulations, with the largest response caused by the increase of anthropogenic emissions. Climate change has diverse impacts on O₃ and its budgets through changes in circulation and meteorological variables. Increased water vapour causes a substantial ozone reduction especially in the tropical lower troposphere (>10 ppbv reduction over the tropical ocean. On the other hand, an enhanced stratosphere-troposphere exchange of ozone, which increases by 80% due to doubling CO₂, contributes to ozone increases in the extratropical free troposphere which subsequently propagate to the surface. Projected higher temperatures favour ozone chemical production and PAN decomposition which lead to high surface ozone levels in certain regions. Enhanced convection transports ozone precursors more rapidly out of the boundary layer resulting in an increase of ozone production in the free troposphere. Lightning-produced NO_x increases by about 22% in the doubled CO₂ climate and contributes to ozone production.

The response to the increase of isoprene emissions shows that the change of ozone is largely determined by background NO_x levels: high

Mid-latitude tropospheric ozone columns from the MOZAIC program: climatology and interannual variability

Directory of Open Access Journals (Sweden)

R. M. Zbinden

2006-01-01

Full Text Available Several thousands of ozone vertical profiles collected in the course of the MOZAIC programme (Measurements of Ozone, Water Vapour, Carbon Monoxide and Nitrogen Oxides by In-Service Airbus Aircraft from August 1994 to February 2002 are investigated to bring out climatological and interannual variability aspects. The study is centred on the most frequently visited MOZAIC airports, i.e. Frankfurt (Germany, Paris (France, New York (USA and the cluster of Tokyo, Nagoya and Osaka (Japan. The analysis focuses on the vertical integration of ozone from the ground to the dynamical tropopause and the vertical integration of stratospheric-origin ozone throughout the troposphere. The characteristics of the MOZAIC profiles: frequency of flights, accuracy, precision, and depth of the troposphere observed, are presented. The climatological analysis shows that the Tropospheric Ozone Column (TOC seasonal cycle ranges from a wintertime minimum at all four stations to a spring-summer maximum in Frankfurt, Paris, and New York. Over Japan, the maximum occurs in spring presumably because of the earlier springtime sun. The incursion of monsoon air masses into the boundary layer and into the mid troposphere then steeply diminishes the summertime value. Boundary layer contributions to the TOC are 10% higher in New York than in Frankfurt and Paris during spring and summer, and are 10% higher in Japan than in New York, Frankfurt and Paris during autumn and early spring. Local and remote anthropogenic emissions, and biomass burning over upstream regions of Asia may be responsible for the larger low- and mid-tropospheric contributions to the tropospheric ozone column over Japan throughout the year except during the summer-monsoon season. A simple Lagrangian analysis has shown that a minimum of 10% of the TOC is of stratospheric-origin throughout the year. Investigation of the short-term trends of the TOC over the period 1995–2001 shows a linear increase 0.7%/year in

Tropospheric Enhancement of Ozone over the UAE

Science.gov (United States)

Abbasi, Naveed Ali; Majeed, Tariq; Iqbal, Mazhar; Kaminski, Jacek; Struzewska, Joanna; Durka, Pawel; Tarasick, David; Davies, Jonathan

2015-04-01

We use the Global Environmental Multiscale - Air Quality (GEM-AQ) model to interpret the vertical profiles of ozone acquired with ozone sounding experiments at the meteorological site located at the Abu Dhabi airport. The purpose of this study is to gain insight into the chemical and dynamical structures in the atmosphere of this unique subtropical location (latitude 24.45N; longitude 54.22E). Ozone observations for years 2012 - 2013 reveal elevated ozone abundances in the range from 70 ppbv to 120 ppbv near 500-400 hPa during summer. The ozone abundances in other seasons are much lower than these values. The preliminary results indicate that summertime enhancement in ozone is associated with the Arabian anticyclones centered over the Zagros Mountains in Iran and the Asir and Hijaz Mountain ranges in Saudi Arabia, and is consistent with TES observations of deuterated water. The model also shows considerable seasonal variation in the tropospheric ozone which is transported from the stratosphere by dynamical processes. The domestic production of ozone in the middle troposphere is estimated and compared GEM-AQ model. It is estimated that about 40-50% of ozone in the UAE is transported from the neighbouring petrochemical industries in the Gulf region. We will present ozone sounding data and GEM-AQ results including a discussion on the high levels of the tropospheric ozone responsible for contaminating the air quality in the UAE. This work is supported by National Research Foundation, UAE.

LOSA-M3: multi-wave polarization scanning lidar for research of the troposphere and cirrus clouds

Science.gov (United States)

Kokhanenko, G. P.; Balin, Yu. S.; Klemasheva, M. G.; Penner, I. E.; Nasonov, S. V.; Samoilova, S. V.

2017-11-01

Lidar is designed to study the aerosol fields of the troposphere and the polarization characteristics of crystal clouds. Two laser wavelengths are used - 1064 and 532 nm, elastic scattering signals and spontaneous Raman scattering of nitrogen (607 nm) are recorded. Lidar is made in a mobile version, allowing its transportation by road and working under expeditionary conditions. The lidar transceiver is placed on a scanning column, which allows to change the direction of sounding within the upper hemisphere at a speed of 1 degree per second. The polarization characteristics of the transmitter and receiver can be changed by rotating the phase plates synchronously with the the laser pulses. In combination with conical scanning of the lidar, this makes it possible to detect the anisotropy of scattering and the possible azimuthal orientation of the crystal particles.

Insufficient Humidification of Respiratory Gases in Patients Who Are Undergoing Therapeutic Hypothermia at a Paediatric and Adult Intensive Care Unit

Directory of Open Access Journals (Sweden)

Yukari Tanaka

2017-01-01

Full Text Available For cooled newborn infants, humidifier settings for normothermic condition provide excessive gas humidity because absolute humidity at saturation is temperature-dependent. To assess humidification of respiratory gases in patients who underwent moderate therapeutic hypothermia at a paediatric/adult intensive care unit, 6 patients were studied over 9 times. Three humidifier settings, 37-default (chamber-outlet, 37°C; Y-piece, 40°C, 33.5-theoretical (chamber-outlet, 33.5°C; Y-piece, 36.5°C, and 33.5-adjusted (optimised setting to achieve saturated vapour at 33.5°C using feedback from a thermohygrometer, were tested. Y-piece gas temperature/humidity and the incidence of high (>40.6 mg/L and low (<32.9 mg/L humidity relative to the target level (36.6 mg/L were assessed. Y-piece gas humidity was 32.0 (26.8–37.3, 22.7 (16.9–28.6, and 36.9 (35.5–38.3 mg/L {mean (95% confidence interval} for 37-default setting, 33.5-theoretical setting, and 33.5-adjusted setting, respectively. High humidity was observed in 1 patient with 37-default setting, whereas low humidity was seen in 5 patients with 37-default setting and 8 patients with 33.5-theoretical setting. With 33.5-adjusted setting, inadequate Y-piece humidity was not observed. Potential risks of the default humidifier setting for insufficient respiratory gas humidification were highlighted in patients cooled at a paediatric/adult intensive care unit. Y-piece gas conditions can be controlled to the theoretically optimal level by adjusting the setting guided by Y-piece gas temperature/humidity.

Insufficient Humidification of Respiratory Gases in Patients Who Are Undergoing Therapeutic Hypothermia at a Paediatric and Adult Intensive Care Unit

Science.gov (United States)

Tanaka, Yukari; Iwata, Sachiko; Kinoshita, Masahiro; Tsuda, Kennosuke; Tanaka, Shoichiro; Hara, Naoko; Shindou, Ryota; Harada, Eimei; Kijima, Ryouji; Yamaga, Osamu; Ohkuma, Hitoe; Ushijima, Kazuo; Sakamoto, Teruo; Yamashita, Yushiro

2017-01-01

For cooled newborn infants, humidifier settings for normothermic condition provide excessive gas humidity because absolute humidity at saturation is temperature-dependent. To assess humidification of respiratory gases in patients who underwent moderate therapeutic hypothermia at a paediatric/adult intensive care unit, 6 patients were studied over 9 times. Three humidifier settings, 37-default (chamber-outlet, 37°C; Y-piece, 40°C), 33.5-theoretical (chamber-outlet, 33.5°C; Y-piece, 36.5°C), and 33.5-adjusted (optimised setting to achieve saturated vapour at 33.5°C using feedback from a thermohygrometer), were tested. Y-piece gas temperature/humidity and the incidence of high (>40.6 mg/L) and low (<32.9 mg/L) humidity relative to the target level (36.6 mg/L) were assessed. Y-piece gas humidity was 32.0 (26.8–37.3), 22.7 (16.9–28.6), and 36.9 (35.5–38.3) mg/L {mean (95% confidence interval)} for 37-default setting, 33.5-theoretical setting, and 33.5-adjusted setting, respectively. High humidity was observed in 1 patient with 37-default setting, whereas low humidity was seen in 5 patients with 37-default setting and 8 patients with 33.5-theoretical setting. With 33.5-adjusted setting, inadequate Y-piece humidity was not observed. Potential risks of the default humidifier setting for insufficient respiratory gas humidification were highlighted in patients cooled at a paediatric/adult intensive care unit. Y-piece gas conditions can be controlled to the theoretically optimal level by adjusting the setting guided by Y-piece gas temperature/humidity. PMID:28512388

Tropospheric Bromine Chemistry: Implications for Present and Pre-industrial Ozone and Mercury

Science.gov (United States)

Parella, J. P.; Jacob, D. J.; Liang, Q.; Zhang, Y.; Mickley, L. J.; Miller, B.; Evans, M. J.; Yang, X.; Pyle, J. A.; Theys, N.;

Tropospheric ozone variations in polar regions; Troposphaerische Ozonvariationen in Polarregionen

Energy Technology Data Exchange (ETDEWEB)

Wessel, S.

1997-08-01

An extensive analysis for the description of chemical and dynamical processes during tropospheric ozone minima in the Arctic and Antarctic was carried out in this work. One main task was the analysis of the source regions of tropospheric ozone destruction and the following transport of ozone depleted air masses to the measuring site. Furtheron the ozone destruction mechanism itself should be examined as well as the efficiency of heterogeneous reactions for the regeneration of non-reative bromine compounds, which seems to be necessary because bromine may be the key component in the destruction of tropospheric ozone in polar regions. (orig./KW) [Deutsch] In der vorliegenden Arbeit wurde eine umfangreiche Analyse zur Beschreibung der chemischen und dynamischen Prozesse waehrend troposphaerischer Ozonminima in der Arktis und Antarktis durchgefuehrt. Ziel war es, die Quellregion des Ozonabbaus sowie den ausloesenden ozonabbauenden Mechanismus zu benennen, die Effizienz heterogener Reaktionen zur Regenerierung nichtreaktiver Bromverbindungen waehrend des Ozonabbaus zu ermitteln und den Transport der ozonarmen Luftmassen zum Messort zu untersuchen. (orig./KW)

North American Tropospheric Ozone Profiles from IONS (INTEX Ozonesonde Network Study, 2004, 2006): Ozone Budgets, Polution Statistics, Satellite Retrievals

Science.gov (United States)

Dougherty, M.; Thompson, A. M.; Witte, J. C.; Miller, S. K.; Oltmans, S. J.; Cooper, O. R.; Tarasick, D. W.; Chatfield, R. B.; Taubman, B. F.; Joseph, E.; Baumgardner, D.; Merrill, J. T.; Morris, G. A.; Rappenglueck, B.; Lefer, B.; Forbes, G.; Newchurch, M. J.; Schmidlin, F. J.; Pierce, R. B.; Leblanc, T.; Dubey, M.; Minschwaner, K.

2007-12-01

During INTEX-B (both Milagro and IMPEX phases in Spring 2006) and during the summer TEXAQS- 2006/GOMACCS period, the INTEX Ozonesonde Network Study (IONS-06) coordinated ozonesonde launches over North America for Aura overpasses. IONS-06 supported aircraft operations and provided profiles for ozone budgets and pollution transport, satellite validation and evaluation of models. In contrast to IONS-04, IONS-06 had a greater range (all but one 2004 IONS site plus a dozen in California, New Mexico, Mexico City, Barbados and southwestern Canada), yielding more than 700 profiles. Tropospheric pollution statistics to guide Aura satellite retrievals and contrasts in UT-LS (upper tropospheric-lower stratospheric) ozone between 2004 and 2006 are presented. With IONS-04 dominated by low-pressure conditions over northeastern North America, UT ozone originated 25% from the stratosphere [Thompson et al., 2007a,b] with significant amounts from aged or relatively fresh pollution and lightning [Cooper et al., 2006; Morris et al., 2006]. Both IONS-04 and IONS-06 summer periods displayed a persistent UT ozone maximum [Cooper et al., 2007] over the south-central US. March 2006 IONS sondes over Mexico manifested persistent UT/LS gravity wave influence and more sporadic pollution. Regional and seasonal contrasts in IONS-06 ozone distributions are described. intexb/ions06.html

Quantifying Aerosol Delivery in Simulated Spontaneously Breathing Patients With Tracheostomy Using Different Humidification Systems With or Without Exhaled Humidity.

Science.gov (United States)

Ari, Arzu; Harwood, Robert; Sheard, Meryl; Alquaimi, Maher Mubarak; Alhamad, Bshayer; Fink, James B

2016-05-01

Aerosol and humidification therapy are used in long-term airway management of critically ill patients with a tracheostomy. The purpose of this study was to determine delivery efficiency of jet and mesh nebulizers combined with different humidification systems in a model of a spontaneously breathing tracheotomized adult with or without exhaled heated humidity. An in vitro model was constructed to simulate a spontaneously breathing adult (tidal volume, 400 mL; breathing frequency, 20 breaths/min; inspiratory-expiratory ratio, 1:2) with a tracheostomy using a teaching manikin attached to a test lung through a collecting filter (Vital Signs Respirgard II). Exhaled heat and humidity were simulated using a cascade humidifier set to deliver 37°C and >95% relative humidity. Albuterol sulfate (2.5 mg/3 mL) was administered with a jet nebulizer (AirLife Misty Max) operated at 10 L/min and a mesh nebulizer (Aeroneb Solo) using a heated pass-over humidifier, unheated large volume humidifier both at 40 L/min output and heat-and-moisture exchanger. Inhaled drug eluted from the filter was analyzed via spectrophotometry (276 nm). Delivery efficiency of the jet nebulizer was less than that of the mesh nebulizer under all conditions (P < .05). Aerosol delivery with each nebulizer was greatest on room air and lowest when heated humidifiers with higher flows were used. Exhaled humidity decreased drug delivery up to 44%. The jet nebulizer was less efficient than the mesh nebulizer in all conditions tested in this study. Aerosol deposition with each nebulizer was lowest with the heated humidifier with high flow. Exhaled humidity reduced inhaled dose of drug compared with a standard model with nonheated/nonhumidified exhalation. Further clinical research is warranted to understand the impact of exhaled humidity on aerosol drug delivery in spontaneously breathing patients with tracheostomy using different types of humidifiers. Copyright © 2016 by Daedalus Enterprises.

Global observations of BrO in the troposphere using GOME-2 satellite data

Science.gov (United States)

Theys, N.; van Roozendael, M.; Hendrick, F.; Xin, Y.; Isabelle, D.; Richter, A.; Mathias, B.; Quentin, E.; Johnston, P. V.; Kreher, K.; Martine, D.

2010-12-01

Measurements from the GOME-2 satellite instrument have been analyzed for tropospheric BrO using a residual technique that combines measured BrO columns and estimates of the stratospheric BrO content from a climatological approach driven by O3 and NO2 observations. Comparisons between the GOME-2 results and correlative data including ground-based BrO vertical columns and total BrO columns derived from SCIAMACHY nadir observations, present a good level of consistency. We show that the adopted technique enables to separate the stratospheric and tropospheric fractions of the measured total BrO columns and allows studying the BrO plumes in polar region in more detail. While several satellite BrO plumes can largely be explained by an influence of stratospheric descending air, we show that numerous tropospheric BrO hotspots are associated to regions with low tropopause heights as well. Elaborating on simulations using the p-TOMCAT tropospheric chemical transport model, this finding is found to be consistent with the mechanism of bromine release through sea salt aerosols production during blowing snow events. Outside the polar region, evidences are provided for a global tropospheric BrO background with columns of 1-3 x 1013 molec/cm2.

Balance of the tropospheric ozone and its relation to stratospheric intrusions indicated by cosmogenic radionuclides. Technical progress report, November 1, 1980-June 30, 1981

International Nuclear Information System (INIS)

Reiter, R.; Kanter, H.J.; Sladkovic, R.; Jaeger, H.; Munzert, K.H.

1981-06-01

The balance of the tropospheric ozone is studied with regard to sources and sinks. The influx of stratospheric ozone through stratospheric intrusions and photochemical production under pure air conditions is discussed. The 4-year measuring series (1977-1980) of the ozone concentration measured at 3 different levels are evaluated, the influence of meteorological parameters is examined. The time variation of the ozone layer between 1000 and 3000 m ASL is investigated as a function of different ozone sources. First results show that stratospheric ozone arriving at the troposphere penetrates only in a few rare cases to the ground layer below 1500 m ASL. Most of the time, the variation of ozone concentration in this layer is determined by photochemical processes which are, in turn, controlled by meteorological parameters. The upper boundary of the photochemically active layer is found at about 500 m above ground. Variability of the concentration of stratospheric aerosol and its optical properties after the volcanic eruptions in the year 1980 are discussed on the basis on lidar backscattering measurements

Global observations of tropospheric BrO columns using GOME-2 satellite data

Directory of Open Access Journals (Sweden)

N. Theys

2011-02-01

Full Text Available Measurements from the GOME-2 satellite instrument have been analyzed for tropospheric BrO using a residual technique that combines measured BrO columns and estimates of the stratospheric BrO content from a climatological approach driven by O₃ and NO₂ observations. Comparisons between the GOME-2 results and BrO vertical columns derived from correlative ground-based and SCIAMACHY nadir observations, present a good level of consistency. We show that the adopted technique enables separation of stratospheric and tropospheric fractions of the measured total BrO columns and allows quantitative study of the BrO plumes in polar regions. While some satellite observed plumes of enhanced BrO can be explained by stratospheric descending air, we show that most BrO hotspots are of tropospheric origin, although they are often associated to regions with low tropopause heights as well. Elaborating on simulations using the p-TOMCAT tropospheric chemical transport model, this result is found to be consistent with the mechanism of bromine release through sea salt aerosols production during blowing snow events. No definitive conclusion can be drawn however on the importance of blowing snow sources in comparison to other bromine release mechanisms. Outside polar regions, evidence is provided for a global tropospheric BrO background with column of 1–3 × 10¹³ molec cm⁻², consistent with previous estimates.

Study of stratosphere-troposphere exchange via 10Be/7Be isotope ratios

International Nuclear Information System (INIS)

Priller, A.; Berger, M.; Golser, R.; Kutschera, W.; Steier, P.; Vockenhuber, C.; Wild, E.M.

2001-01-01

Full text: The present study is part of the European project STACCATO (influence of stratosphere-troposphere exchange in a changing climate on atmospheric transport and oxidation capacity). Stratosphere-troposphere exchange (STE) is one of the key factors controlling the budgets of ozone, water vapor and other substances in both the troposphere and the lower stratosphere. However, its contribution to their ozone budget relative to photo-chemical ozone formation from natural and anthropogenic precursor emissions is still uncertain. An international effort is made to estimate the strength of STE and its impact on tropospheric chemistry. The two cosmogenic radioisotopes of beryllium, 10 Be and 7 Be have very different half-lives of 1.51 Ma and 53.4 d, respectively. The combination of production rates, half-lives and different residence times in the stratosphere and troposphere, respectively, results in 10 Be/ 7 Be isotope ratios which can be used as fingerprints for STE. This ratio helps to give a much improved estimate of STE. However, only few 10 Be measurements exist, because its detection requires the rather elaborate method of accelerator mass spectrometry (AMS). At the AMS facility VERA we are now measuring the 10 Be content of air filters from the high-alpine stations 'Hoher Sonnblick', Austria, and 'Zugspitze', Germany. The TBe content is measured separately by decay counting. In this presentation, we want to describe the method of measuring 10 Be with AMS, and to discuss the results of first 10 Be/ 7 Be ratios. (author)

The distribution and speciation of mercury in the free troposphere of the Pacific Northwest

Science.gov (United States)

Swartzendruber, Philip C.

2009-12-01

suggests that upper tropospheric influence is not a controlling factor. There was no mean vertical trend in total Hg (GEM + RGM) up to 5 km. The only factor common to all high RGM, was low aerosol scattering (<2 M/m).

Respiratory mechanics and plasma levels of tumor necrosis factor alpha and interleukin 6 are affected by gas humidification during mechanical ventilation in dogs.

Science.gov (United States)

Hernández-Jiménez, Claudia; García-Torrentera, Rogelio; Olmos-Zúñiga, J Raúl; Jasso-Victoria, Rogelio; Gaxiola-Gaxiola, Miguel O; Baltazares-Lipp, Matilde; Gutiérrez-González, Luis H

2014-01-01

The use of dry gases during mechanical ventilation has been associated with the risk of serious airway complications. The goal of the present study was to quantify the plasma levels of TNF-alpha and IL-6 and to determine the radiological, hemodynamic, gasometric, and microscopic changes in lung mechanics in dogs subjected to short-term mechanical ventilation with and without humidification of the inhaled gas. The experiment was conducted for 24 hours in 10 dogs divided into two groups: Group I (n = 5), mechanical ventilation with dry oxygen dispensation, and Group II (n = 5), mechanical ventilation with oxygen dispensation using a moisture chamber. Variance analysis was used. No changes in physiological, hemodynamic, or gasometric, and radiographic constants were observed. Plasma TNF-alpha levels increased in group I, reaching a maximum 24 hours after mechanical ventilation was initiated (ANOVA p = 0.77). This increase was correlated to changes in mechanical ventilation. Plasma IL-6 levels decreased at 12 hours and increased again towards the end of the study (ANOVA p>0.05). Both groups exhibited a decrease in lung compliance and functional residual capacity values, but this was more pronounced in group I. Pplat increased in group I (ANOVA p = 0.02). Inhalation of dry gas caused histological lesions in the entire respiratory tract, including pulmonary parenchyma, to a greater extent than humidified gas. Humidification of inspired gases can attenuate damage associated with mechanical ventilation.

Respiratory mechanics and plasma levels of tumor necrosis factor alpha and interleukin 6 are affected by gas humidification during mechanical ventilation in dogs.

Directory of Open Access Journals (Sweden)

Claudia Hernández-Jiménez

Full Text Available The use of dry gases during mechanical ventilation has been associated with the risk of serious airway complications. The goal of the present study was to quantify the plasma levels of TNF-alpha and IL-6 and to determine the radiological, hemodynamic, gasometric, and microscopic changes in lung mechanics in dogs subjected to short-term mechanical ventilation with and without humidification of the inhaled gas. The experiment was conducted for 24 hours in 10 dogs divided into two groups: Group I (n = 5, mechanical ventilation with dry oxygen dispensation, and Group II (n = 5, mechanical ventilation with oxygen dispensation using a moisture chamber. Variance analysis was used. No changes in physiological, hemodynamic, or gasometric, and radiographic constants were observed. Plasma TNF-alpha levels increased in group I, reaching a maximum 24 hours after mechanical ventilation was initiated (ANOVA p = 0.77. This increase was correlated to changes in mechanical ventilation. Plasma IL-6 levels decreased at 12 hours and increased again towards the end of the study (ANOVA p>0.05. Both groups exhibited a decrease in lung compliance and functional residual capacity values, but this was more pronounced in group I. Pplat increased in group I (ANOVA p = 0.02. Inhalation of dry gas caused histological lesions in the entire respiratory tract, including pulmonary parenchyma, to a greater extent than humidified gas. Humidification of inspired gases can attenuate damage associated with mechanical ventilation.

Measurements of ice nucleating particle concentrations at 242 K in the free troposphere

Science.gov (United States)

Lacher, L.; Lohmann, U.; Boose, Y.; Zipori, A.; Herrmann, E.; Bukowiecki, N.; Steinbacher, M.; Gute, E.; Kanji, Z. A.

2017-12-01

Clouds containing ice play an important role in the Earth's system, but some fundamental knowledge on their formation and further development is still missing. The phase change from vapor or liquid to ice in the atmosphere can occur heterogeneously in the presence of ice nucleating particles (INPs) at temperatures warmer, and supersaturations lower than required for homogeneous freezing. Only a small fraction of particles in an environment relevant for the occurrence of ice- and mixed-phase clouds are INPs, and their identification and quantification remains challenging. We measure INP concentrations with the ETH Horizontal Ice Nucleation Chamber (HINC) at the High Altitude Research Station Jungfraujoch (JFJ) during several field campaigns in different seasons and years. The measurements are performed at 242 K and above water saturation, representing ice- and mixed-phase clouds conditions. Due to its elevation of 3580 m a.s.l. the site encounters mostly free tropospheric conditions, and is influenced by boundary layer injections up to 80% of the time in summer. JFJ regularly encounters Saharan dust events and receives air masses of marine origin, which can both occur within the free troposphere. Our measurements show that INP concentrations in the free troposphere do not follow a seasonal cycle. They are remarkably constant, with concentrations from 0.5 - 8 L-1 (interquartile range), which compares well to measurements performed under the same conditions at another location within the free troposphere, the Izaña Atmospheric Research Station in Tenerife. At JFJ, correlations with parameters of physical properties of ambient particles, meteorology and air mass characteristics do not show a single best estimator to predict INP concentrations, emphasizing the complexity of ice nucleation in the free troposphere. Increases in INP concentrations of a temporary nature were observed in the free troposphere during Saharan dust events and marine air mass influence, which

Vertical profile of tropospheric ozone derived from synergetic retrieval using three different wavelength ranges, UV, IR, and microwave: sensitivity study for satellite observation

Directory of Open Access Journals (Sweden)

T. O. Sato

2018-03-01

Full Text Available We performed a feasibility study of constraining the vertical profile of the tropospheric ozone by using a synergetic retrieval method on multiple spectra, i.e., ultraviolet (UV, thermal infrared (TIR, and microwave (MW ranges, measured from space. This work provides, for the first time, a quantitative evaluation of the retrieval sensitivity of the tropospheric ozone by adding the MW measurement to the UV and TIR measurements. Two observation points in East Asia (one in an urban area and one in an ocean area and two observation times (one during summer and one during winter were assumed. Geometry of line of sight was nadir down-looking for the UV and TIR measurements, and limb sounding for the MW measurement. The retrieval sensitivities of the ozone profiles in the upper troposphere (UT, middle troposphere (MT, and lowermost troposphere (LMT were estimated using the degree of freedom for signal (DFS, the pressure of maximum sensitivity, reduction rate of error from the a priori error, and the averaging kernel matrix, derived based on the optimal estimation method. The measurement noise levels were assumed to be the same as those for currently available instruments. The weighting functions for the UV, TIR, and MW ranges were calculated using the SCIATRAN radiative transfer model, the Line-By-Line Radiative Transfer Model (LBLRTM, and the Advanced Model for Atmospheric Terahertz Radiation Analysis and Simulation (AMATERASU, respectively. The DFS value was increased by approximately 96, 23, and 30 % by adding the MW measurements to the combination of UV and TIR measurements in the UT, MT, and LMT regions, respectively. The MW measurement increased the DFS value of the LMT ozone; nevertheless, the MW measurement alone has no sensitivity to the LMT ozone. The pressure of maximum sensitivity value for the LMT ozone was also increased by adding the MW measurement. These findings indicate that better information on LMT ozone can be obtained by adding

Vertical profile of tropospheric ozone derived from synergetic retrieval using three different wavelength ranges, UV, IR, and microwave: sensitivity study for satellite observation

Science.gov (United States)

Sato, Tomohiro O.; Sato, Takao M.; Sagawa, Hideo; Noguchi, Katsuyuki; Saitoh, Naoko; Irie, Hitoshi; Kita, Kazuyuki; Mahani, Mona E.; Zettsu, Koji; Imasu, Ryoichi; Hayashida, Sachiko; Kasai, Yasuko

2018-03-01

We performed a feasibility study of constraining the vertical profile of the tropospheric ozone by using a synergetic retrieval method on multiple spectra, i.e., ultraviolet (UV), thermal infrared (TIR), and microwave (MW) ranges, measured from space. This work provides, for the first time, a quantitative evaluation of the retrieval sensitivity of the tropospheric ozone by adding the MW measurement to the UV and TIR measurements. Two observation points in East Asia (one in an urban area and one in an ocean area) and two observation times (one during summer and one during winter) were assumed. Geometry of line of sight was nadir down-looking for the UV and TIR measurements, and limb sounding for the MW measurement. The retrieval sensitivities of the ozone profiles in the upper troposphere (UT), middle troposphere (MT), and lowermost troposphere (LMT) were estimated using the degree of freedom for signal (DFS), the pressure of maximum sensitivity, reduction rate of error from the a priori error, and the averaging kernel matrix, derived based on the optimal estimation method. The measurement noise levels were assumed to be the same as those for currently available instruments. The weighting functions for the UV, TIR, and MW ranges were calculated using the SCIATRAN radiative transfer model, the Line-By-Line Radiative Transfer Model (LBLRTM), and the Advanced Model for Atmospheric Terahertz Radiation Analysis and Simulation (AMATERASU), respectively. The DFS value was increased by approximately 96, 23, and 30 % by adding the MW measurements to the combination of UV and TIR measurements in the UT, MT, and LMT regions, respectively. The MW measurement increased the DFS value of the LMT ozone; nevertheless, the MW measurement alone has no sensitivity to the LMT ozone. The pressure of maximum sensitivity value for the LMT ozone was also increased by adding the MW measurement. These findings indicate that better information on LMT ozone can be obtained by adding constraints

An investigation into a laboratory scale bubble column humidification dehumidification desalination system powered by biomass energy

International Nuclear Information System (INIS)

Rajaseenivasan, T.; Srithar, K.

2017-01-01

Highlights: • A biomass based humidification dehumidification desalination system is tested. • System is analyzed with the direct and preheated air supply. • Highest distillate rate of 6.1 kg/h is collected with the preheated air supply. • The minimum fuel feed of 0.2 kg is needed to produce 1 kg of fresh water. - Abstract: This article describes a biomass powered bubble column humidification-dehumidification desalination system. This system mainly consists of a biomass stove, air heat exchanger, bubble column humidifier and dehumidifier. Saw dust briquettes are used as biomass fuel in the stove. First level of experiments are carried out in bubble column humidifier with ambient air supply to select the best water depth, bubble pipe hole diameter and water temperature. Experiments are conducted by integrating the humidifier with the dehumidifier. Air is sent to the humidifier with and without pre-heating. Preheating of air is carried out in the air heat exchanger by using the flue gas and flame from the combustion chamber. It is observed that the humidifier ability is augmented with the rise in water depth, water temperature, mass flow rate of air and cooling water flow rate, and reduction in bubble pipe hole diameter. It is found from Taguchi analysis that the water temperature dominates in controlling the humidifier performance compared to other parameters. Better specific humidity is recorded with a bubble pipe hole diameter of 1 mm, water depth of 170 mm and water temperature of 60 °C. Highest distillate of 6.1 kg/h and 3.5 kg/h is collected for the HDH desalination system with preheated air and direct air supply respectively. Recovery of waste heat using an air heat exchanger reduces the fuel consumption from 0.36 kg to 0.2 kg for producing 1 kg of distilled water. Lowest distilled water cost of 0.0133 US $/kg through preheated air supply and 0.0231 US $/kg through direct air supply is observed. A correlation is developed to estimate the mass transfer

Application of ray-traced tropospheric slant delays to geodetic VLBI analysis

Science.gov (United States)

Hofmeister, Armin; Böhm, Johannes

2017-08-01

The correction of tropospheric influences via so-called path delays is critical for the analysis of observations from space geodetic techniques like the very long baseline interferometry (VLBI). In standard VLBI analysis, the a priori slant path delays are determined using the concept of zenith delays, mapping functions and gradients. The a priori use of ray-traced delays, i.e., tropospheric slant path delays determined with the technique of ray-tracing through the meteorological data of numerical weather models (NWM), serves as an alternative way of correcting the influences of the troposphere on the VLBI observations within the analysis. In the presented research, the application of ray-traced delays to the VLBI analysis of sessions in a time span of 16.5 years is investigated. Ray-traced delays have been determined with program RADIATE (see Hofmeister in Ph.D. thesis, Department of Geodesy and Geophysics, Faculty of Mathematics and Geoinformation, Technische Universität Wien. http://resolver.obvsg.at/urn:nbn:at:at-ubtuw:1-3444, 2016) utilizing meteorological data provided by NWM of the European Centre for Medium-Range Weather Forecasts (ECMWF). In comparison with a standard VLBI analysis, which includes the tropospheric gradient estimation, the application of the ray-traced delays to an analysis, which uses the same parameterization except for the a priori slant path delay handling and the used wet mapping factors for the zenith wet delay (ZWD) estimation, improves the baseline length repeatability (BLR) at 55.9% of the baselines at sub-mm level. If no tropospheric gradients are estimated within the compared analyses, 90.6% of all baselines benefit from the application of the ray-traced delays, which leads to an average improvement of the BLR of 1 mm. The effects of the ray-traced delays on the terrestrial reference frame are also investigated. A separate assessment of the RADIATE ray-traced delays is carried out by comparison to the ray-traced delays from the

Variable influence on the equatorial troposphere associated with ...

Indian Academy of Sciences (India)

sphere to the stratosphere due to the uneven land profile (Matsuno ... an impact of the North Atlantic ocean-atmosphere heat flux, Eurasian ... convective clouds in the stratosphere–troposphere dynamics ..... modeling benchmarks; J. Clim.

Trace gas composition in the free and upper troposphere over Asia: Examining the influence of long-range transport and convection of local pollution

Science.gov (United States)

Baker, A. K.; Traud, S.; Brenninkmeijer, C. A.; Hoor, P. M.; Neumaier, M.; Oram, D.; Rauthe-Schöch, A.; Schloegl, S.; Sprung, D.; Slemr, F.; van Velthoven, P.; Wernli, H.; Zahn, A.; Ziereis, H.

2013-12-01

Between May 2005 and March 2008 the CARIBIC observatory (Civil Aircraft for the Regular Investigation of the atmosphere Based on an Instrument Container) was deployed to make atmospheric observations during 21 round-trip flights between Frankfurt, Germany and Manila, the Philippines with a stopover in Guangzhou, China. This nearly 3 year flight series provides us with information about atmospheric composition in the free and upper troposphere over Asia during all seasons and was used to investigate seasonal and regional differences in trace gas distributions and the relative influences of long range transport and convected local air masses on composition. The flight route was separated into three different regions having unique characteristics in transport and composition; these were Western Asia (5°E to 70°E), Central Asia (70°E to 100°E) and East Asia (100°E to 125°E). The region over Western Asia was heavily influenced by long range transport of air masses from North America and had elevated levels of NOy and acetone, while the region over East Asia was mostly influenced by convected local (South East Asian) pollution, particularly from biomass/biofuel burning as indicated by high levels of acetonitrile and carbon monoxide. Air masses over Central Asia were found to be influenced by both recently convected air masses from the Indian subcontinent and mid-range transport from Eastern Europe and the Middle East. Elevated levels of propane and other non-methane hydrocarbons, both with and without concommitant elevations in other trace gases (i.e. carbon monoxide, acetonitrile) were a persisent feature of this region in all seasons except summer, and were particularly prominent in fall. Influences on composition over Central Asia were investigated more thoroughly in a case study from a series of flights in October 2006, and elevated levels of pollutants were found to be the result of convective transport of both biomass/biofuel burning and urban emissions from

Variations in Upper-Level Water Vapor Transport Diagnosed from Climatological Satellite Data

Science.gov (United States)

Lerner, Jeffrey A; Jedlovee, Gary J.; Atkinson, Robert J.

1998-01-01

GOES-7 VAS measurements during the Pathfinder period (1987-88) have been analysed to reveal seasonal and interannual variations in moisture transport. Long term measurements of quality winds and humidity from satellite estimates show superior benefit in diagnosing middle and upper tropospheric large scale climate variations such as ENSO events and direct circulation systems such as the Hadley Cell. A water Vapor Transport Index (WVTI) has been developed to diagnose preferred regions of strong moisture transport and to gauge the seasonal and interannual intensities detected in the GOES viewing area. Second-order variables that may be derived from GOES winds will be also discussed on the poster.

Implementation of Tropospheric Emissions: Monitoring of Pollution (TEMPO)

Science.gov (United States)

Chance, K.; Liu, X.; Suleiman, R. M.; Flittner, D. E.; Al-Saadi, J. A.; Janz, S. J.

2014-12-01

The updated status of TEMPO, as it proceeds from formulation phase into implementation phase is presented. TEMPO, the first NASA Earth Venture Instrument, will measure atmospheric pollution for greater North America from space using ultraviolet and visible spectroscopy. TEMPO measures from Mexico City to the Canadian oil sands, and from the Atlantic to the Pacific, hourly and at high spatial resolution. TEMPO provides a tropospheric measurement suite that includes the key elements of tropospheric air pollution chemistry. Measurements are from geostationary (GEO) orbit, to capture the inherent high variability in the diurnal cycle of emissions and chemistry. The small product spatial footprint resolves pollution sources at sub-urban scale. Together, this temporal and spatial resolution improves emission inventories, monitors population exposure, and enables effective emission-control strategies. TEMPO takes advantage of a GEO host spacecraft to provide a modest cost mission that measures the spectra required to retrieve O3, NO2, SO2, H2CO, C2H2O2, H2O, aerosols, cloud parameters, and UVB radiation. TEMPO thus measures the major elements, directly or by proxy, in the tropospheric O3 chemistry cycle. Multi-spectral observations provide sensitivity to O3 in the lowermost troposphere, reducing uncertainty in air quality predictions by 50%. TEMPO quantifies and tracks the evolution of aerosol loading. It provides near-real-time air quality products that will be made widely, publicly available. TEMPO provides much of the atmospheric measurement capability recommended for GEO-CAPE in the 2007 National Research Council Decadal Survey, Earth Science and Applications from Space: National Imperatives for the Next Decade and Beyond. GEO-CAPE is not planned for implementation this decade. However, instruments from Europe (Sentinel 4) and Asia (GEMS) will form parts of a global GEO constellation for pollution monitoring later this decade, with a major focus on intercontinental

Chemistry and dynamics of the lower troposphere over North America and the North Atlantic Ocean in fall 1997 observed using an airborne UV DIAL system

Science.gov (United States)

Grant, William B.; Butler, Carolyn F.; Fenn, Marta A.; Kooi, Susan A.; Browell, Edward V.; Fuelberg, Henry

1998-01-01

The NASA Langley Research Center's airborne UV Differential Absorption Lidar (DIAL) system participated in the Subsonic Assessment, Ozone and Nitrogen Oxide Experiment (SONEX) mission from October 13 to November 12, 1997. The purpose of the mission was to study the upper troposphere/lower stratosphere in and near the North Atlantic flight corridor to better understand this region of the atmosphere and how civilian air travel in the corridor might be affecting the atmospheric chemistry. Bases of operations included NASA Ames, California (37.4 deg N, 122.1 deg W); Bangor, Maine (44.8 deg N, 68.8 deg W); Shannon, Ireland (52.7 deg N, 8.9 deg W); and Lajes, Terceira Island, Azores (38.8 deg N, 27.1 deg W). Since the UV DIAL system observes in the nadir as well as the zenith, aerosol and ozone data were obtained from near the Earth's surface to the lower stratosphere. A number of interesting features were noted relating to both chemistry and dynamics of the troposphere, which are reported here.

Quantifying the causes of differences in tropospheric OH within global models

Science.gov (United States)

Nicely, Julie M.; Salawitch, Ross J.; Canty, Timothy; Anderson, Daniel C.; Arnold, Steve R.; Chipperfield, Martyn P.; Emmons, Louisa K.; Flemming, Johannes; Huijnen, Vincent; Kinnison, Douglas E.; Lamarque, Jean-François; Mao, Jingqiu; Monks, Sarah A.; Steenrod, Stephen D.; Tilmes, Simone; Turquety, Solene

2017-02-01

The hydroxyl radical (OH) is the primary daytime oxidant in the troposphere and provides the main loss mechanism for many pollutants and greenhouse gases, including methane (CH4). Global mean tropospheric OH differs by as much as 80% among various global models, for reasons that are not well understood. We use neural networks (NNs), trained using archived output from eight chemical transport models (CTMs) that participated in the Polar Study using Aircraft, Remote Sensing, Surface Measurements and Models, of Climate, Chemistry, Aerosols and Transport Model Intercomparison Project (POLMIP), to quantify the factors responsible for differences in tropospheric OH and resulting CH4 lifetime (τCH4) between these models. Annual average τCH4, for loss by OH only, ranges from 8.0 to 11.6 years for the eight POLMIP CTMs. The factors driving these differences were quantified by inputting 3-D chemical fields from one CTM into the trained NN of another CTM. Across all CTMs, the largest mean differences in τCH4 (ΔτCH4) result from variations in chemical mechanisms (ΔτCH4 = 0.46 years), the photolysis frequency (J) of O3 → O(1D) (0.31 years), local O3 (0.30 years), and CO (0.23 years). The ΔτCH4 due to CTM differences in NOx (NO + NO2) is relatively low (0.17 years), although large regional variation in OH between the CTMs is attributed to NOx. Differences in isoprene and J(NO2) have negligible overall effect on globally averaged tropospheric OH, although the extent of OH variations due to each factor depends on the model being examined. This study demonstrates that NNs can serve as a useful tool for quantifying why tropospheric OH varies between global models, provided that essential chemical fields are archived.

Seasonal variations and vertical features of aerosol particles in the Antarctic troposphere

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K. Hara

2011-06-01

Full Text Available Tethered balloon-borne aerosol measurements were conducted at Syowa Station, Antarctica during the 46th Japanese Antarctic expedition (2005–2006. The CN concentration reached a maximum in the summer, although the number concentrations of fine particles (D_p>0.3 μm and coarse particles (D_p>2.0 μm increased during the winter–spring. The CN concentration was 30–2200 cm⁻³ near the surface (surface – 500 m and 7–7250 cm⁻³ in the lower free troposphere (>1500 m. During the austral summer, higher CN concentration was often observed in the lower free troposphere, where the number concentrations in fine and coarse modes were remarkably lower. The frequent appearance of higher CN concentrations in the free troposphere relative to continuous aerosol measurements at the ground strongly suggests that new particle formation is more likely to occur in the lower free troposphere in Antarctic regions. Seasonal variations of size distribution of fine-coarse particles show that the contribution of the coarse mode was greater in the winter–spring than in summer because of the dominance of sea-salt particles in the winter–spring. The number concentrations of fine and coarse particles were high in air masses from the ocean and mid-latitudes. Particularly, aerosol enhancement was observed not only in the boundary layer, but also in the lower free troposphere during and immediately after Antarctic haze events occurring in May, July and September.

Effect of heat and moisture exchanger (HME positioning on inspiratory gas humidification

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Nishimura Masaji

2006-08-01

Full Text Available Abstract Background In mechanically ventilated patients, we investigated how positioning the heat and moisture exchanger (HME at different places on the ventilator circuit affected inspiratory gas humidification. Methods Absolute humidity (AH and temperature (TEMP at the proximal end of endotracheal tube (ETT were measured in ten mechanically ventilated patients. The HME was connected either directly proximal to the ETT (Site 1 or at before the circuit Y-piece (Site 2: distance from proximal end of ETT and Site 2 was about 19 cm (Figure. 1. Two devices, Hygrobac S (Mallinckrodt Dar, Mirandola, Italy and Thermovent HEPA (Smiths Medical International Ltd., Kent, UK were tested. AH and TEMP were measured with a hygrometer (Moiscope, MERA Co., Ltd., Tokyo, Japan. Results Hygrobac S provided significantly higher AH and TEMP at both sites than Thermovent HEPA. Both Hygrobac S and with Thermovent HEPA provided significantly higher AH and TEMP when placed proximally to the ETT. Conclusion Although placement proximal to the ETT improved both AH and TEMP in both HMEs tested, one HME performed better in the distal position than the other HME in the proximal position. We conclude the both the type and placement of HME can make a significant difference in maintaining AH and TEMP during adult ventilation.

Effect of heat and moisture exchanger (HME) positioning on inspiratory gas humidification

Science.gov (United States)

Inui, Daisuke; Oto, Jun; Nishimura, Masaji

2006-01-01

Background In mechanically ventilated patients, we investigated how positioning the heat and moisture exchanger (HME) at different places on the ventilator circuit affected inspiratory gas humidification. Methods Absolute humidity (AH) and temperature (TEMP) at the proximal end of endotracheal tube (ETT) were measured in ten mechanically ventilated patients. The HME was connected either directly proximal to the ETT (Site 1) or at before the circuit Y-piece (Site 2: distance from proximal end of ETT and Site 2 was about 19 cm) (Figure. 1). Two devices, Hygrobac S (Mallinckrodt Dar, Mirandola, Italy) and Thermovent HEPA (Smiths Medical International Ltd., Kent, UK) were tested. AH and TEMP were measured with a hygrometer (Moiscope, MERA Co., Ltd., Tokyo, Japan). Results Hygrobac S provided significantly higher AH and TEMP at both sites than Thermovent HEPA. Both Hygrobac S and with Thermovent HEPA provided significantly higher AH and TEMP when placed proximally to the ETT. Conclusion Although placement proximal to the ETT improved both AH and TEMP in both HMEs tested, one HME performed better in the distal position than the other HME in the proximal position. We conclude the both the type and placement of HME can make a significant difference in maintaining AH and TEMP during adult ventilation. PMID:16895607

Tropospheric ozone. Formation, properties, effects. Expert opinion