WorldWideScience

Sample records for atmospheric water vapor

  1. DMSP SSMT/2 - Atmospheric Water Vapor Profiler

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The SSM/T-2 sensor is a five channel, total power microwave radiometer with three channels situated symmetrically about the 183.31 GHz water vapor resonance line and...

  2. Lunar absorption spectrophotometer for measuring atmospheric water vapor.

    Science.gov (United States)

    Querel, Richard R; Naylor, David A

    2011-02-01

    A novel instrument has been designed to measure the nighttime atmospheric water vapor column abundance by near-infrared absorption spectrophotometry of the Moon. The instrument provides a simple, effective, portable, and inexpensive means of rapidly measuring the water vapor content along the lunar line of sight. Moreover, the instrument is relatively insensitive to the atmospheric model used and, thus, serves to provide an independent calibration for other measures of precipitable water vapor from both ground- and space-based platforms.

  3. Atmospheric solar heating rate in the water vapor bands

    Science.gov (United States)

    Chou, Ming-Dah

    1986-01-01

    The total absorption of solar radiation by water vapor in clear atmospheres is parameterized as a simple function of the scaled water vapor amount. For applications to cloudy and hazy atmospheres, the flux-weighted k-distribution functions are computed for individual absorption bands and for the total near-infrared region. The parameterization is based upon monochromatic calculations and follows essentially the scaling approximation of Chou and Arking, but the effect of temperature variation with height is taken into account in order to enhance the accuracy. Furthermore, the spectral range is extended to cover the two weak bands centered at 0.72 and 0.82 micron. Comparisons with monochromatic calculations show that the atmospheric heating rate and the surface radiation can be accurately computed from the parameterization. Comparisons are also made with other parameterizations. It is found that the absorption of solar radiation can be computed reasonably well using the Goody band model and the Curtis-Godson approximation.

  4. Interpolating atmospheric water vapor delay by incorporating terrain elevation information

    Science.gov (United States)

    Xu, W. B.; Li, Z. W.; Ding, X. L.; Zhu, J. J.

    2011-09-01

    In radio signal-based observing systems, such as Global Positioning System (GPS) and Interferometric Synthetic Aperture Radar (InSAR), the water vapor in the atmosphere will cause delays during the signal transmission. Such delays vary significantly with terrain elevation. In the case when atmospheric delays are to be eliminated from the measured raw signals, spatial interpolators may be needed. By taking advantage of available terrain elevation information during spatial interpolation process, the accuracy of the atmospheric delay mapping can be considerably improved. This paper first reviews three elevation-dependent water vapor interpolation models, i.e., the Best Linear Unbiased Estimator in combination with the water vapor Height Scaling Model (BLUE + HSM), the Best Linear Unbiased Estimator coupled with the Elevation-dependent Covariance Model (BLUE + ECM), and the Simple Kriging with varying local means based on the Baby semi-empirical model (SKlm + Baby for short). A revision to the SKlm + Baby model is then presented, where the Onn water vapor delay model is adopted to substitute the inaccurate Baby semi-empirical model (SKlm + Onn for short). Experiments with the zenith wet delays obtained through the GPS observations from the Southern California Integrated GPS Network (SCIGN) demonstrate that the SKlm + Onn model outperforms the other three. The RMS of SKlm + Onn is only 0.55 cm, while those of BLUE + HSM, BLUE + ECM and SKlm + Baby amount to 1.11, 1.49 and 0.77 cm, respectively. The proposed SKlm + Onn model therefore represents an improvement of 29-63% over the other known models.

  5. A new passive sampler for collecting atmospheric tritiated water vapor

    Science.gov (United States)

    Feng, Bin; Chen, Bo; Zhuo, Weihai; Zhang, Weiyuan

    2017-04-01

    A new passive sampler was developed for collecting environmental tritiated water vapor. The construction of the sampler was improved according to computational fluid dynamics (CFD) simulations in which the influence on vapor collection by the turbulence inside the sampler was considered. Through changes in temperature from 5 °C to 35 °C and relative humidity from 45% to 90%, the new sampler revealed stable performance of the sampling rate. Compared with the previous samplers, the new sampler significantly lowered the effect of wind speed. Using the adsorption kinetic curve of the sampler provided in the co-comparison experiments, the quantitative relationship between the mass of adsorbed water and the cumulative absolute humidity exposure was established. Field applications in the vicinity of a nuclear power plant show that the data obtained by the new samplers is consistent with the active measurement. The sampler was preliminarily proven to be reliable and flexible for field investigation of HTO in the atmosphere.

  6. LBA-ECO CD-02 Oxygen Isotopes of Plant Tissue Water and Atmospheric Water Vapor

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set reports the oxygen isotope signatures of water extracted from plant tissue (xylem from the stems and leaf tissue) and of atmospheric water vapor from...

  7. Water vapor measurement system in global atmospheric sampling program, appendix

    Science.gov (United States)

    Englund, D. R.; Dudzinski, T. J.

    1982-01-01

    The water vapor measurement system used in the NASA Global Atmospheric Sampling Program (GASP) is described. The system used a modified version of a commercially available dew/frostpoint hygrometer with a thermoelectrically cooled mirror sensor. The modifications extended the range of the hygrometer to enable air sample measurements with frostpoint temperatures down to -80 C at altitudes of 6 to 13 km. Other modifications were made to permit automatic, unattended operation in an aircraft environment. This report described the hygrometer, its integration with the GASP system, its calibration, and operational aspects including measurement errors. The estimated uncertainty of the dew/frostpoint measurements was + or - 1.7 Celsius.

  8. Atmospheric water vapor retrieval from Landsat 8 thermal infrared images

    Science.gov (United States)

    Ren, Huazhong; Du, Chen; Liu, Rongyuan; Qin, Qiming; Yan, Guangjian; Li, Zhao-Liang; Meng, Jinjie

    2015-03-01

    Atmospheric water vapor (wv) is required for the accurate retrieval of the land surface temperature from remote sensing data and other applications. This work aims to estimate wv from Landsat 8 Thermal InfraRed Sensor (TIRS) images using a new modified split-window covariance-variance ratio (MSWCVR) method on the basis of the brightness temperatures of two thermal infrared bands. Results show that the MSWCVR method can theoretically retrieve wv with an accuracy better than 0.3 g/cm2 for dry atmosphere (wv Robotic Network) ground-measured data and MODIS (Moderate Resolution Imaging Spectroradiometer) products. The results show that the retrieved wv from the TIRS data is highly correlated with the wv of AERONET and MODIS but is generally larger. This difference was probably attributed to the uncertainty of radiometric calibration and stray light coming outside from field of view of TIRS instrument in the current images. Consequently, the data quality and radiometric calibration of the TIRS data should be improved in the future.

  9. Visualization of Atmospheric Water Vapor Data for SAGE

    Science.gov (United States)

    Kung, Mou-Liang; Chu, W. P. (Technical Monitor)

    2000-01-01

    The goal of this project was to develop visualization tools to study the water vapor dynamics using the Stratospheric Aerosol and Gas Experiment 11 (SAGE 11) water vapor data. During the past years, we completed the development of a visualization tool called EZSAGE, and various Gridded Water Vapor plots, tools deployed on the web to provide users with new insight into the water vapor dynamics. Results and experiences from this project, including papers, tutorials and reviews were published on the main Web page. Additional publishing effort has been initiated to package EZSAGE software for CD production and distribution. There have been some major personnel changes since Fall, 1998. Dr. Mou-Liang Kung, a Professor of Computer Science assumed the PI position vacated by Dr. Waldo Rodriguez who was on leave. However, former PI, Dr. Rodriguez continued to serve as a research adviser to this project to assure smooth transition and project completion. Typically in each semester, five student research assistants were hired and trained. Weekly group meetings were held to discuss problems, progress, new research direction, and activity planning. Other small group meetings were also held regularly for different objectives of this project. All student research assistants were required to submit reports for conference submission.

  10. An interim reference model for the variability of the middle atmosphere water vapor distribution

    Science.gov (United States)

    Remsberg, E. E.; Russell, J. M., III; Wu, C.-Y.

    1990-01-01

    A reference model for the middle atmosphere water vapor distribution for some latitudes and seasons was developed using two data sets. One is the seven months of Nimbus LIMS data obtained during November 1978 to May 1979 over the range 64 deg S - 84 deg N latitude and from about 100-mb to 1-mb altitude, and the other is represented by water vapor profiles from 0.2 mb to 0.01 mb in the mid-mesosphere, measured on ground at several fixed mid-latitude sites in the Northern Hemisphere, using microwave-emission techniques. This model provides an interim water vapor profile for the entire vertical range of the middle atmosphere, with accuracies of better than 25 percent. The daily variability of stratospheric water vapor profiles about the monthly mean is demonstrated, and information is provided on the longitudinal variability of LIMS water vapor profiles about the daily, weekly, and monthly zonal means.

  11. Determination of water vapor and aerosol densities in the tropospheric atmosphere from nitrogen and water vapor raman signals

    CERN Document Server

    Kim, D H; Lee, J M; Yeon, K H; Choi, S C

    1998-01-01

    A Raman lidar system has been developed for the measurement of the water-vapor mixing ratio and the aerosol backscatter and extinction coefficients. To suppress the elastic scattering from the XeCl excimer laser, an acetone edge filter and narrow-band interference filters are used. By using independently calculated backscatter and extinction coefficients, we calculate the lidar ratios (extinction coefficient divided by the backscatter coefficient). The obtained ratios between 30 and 50 sr explain the special characteristics of the aerosol existing in the atmosphere. These ratios are also used as important parameters in the lidar inversion program. We have also obtained the water-vapor mixing ratio and find that big differences exist between the ratios inside the boundary layer and those of other regions.

  12. Development and Validation of Water Vapor Tracers as Diagnostics for the Atmospheric Hydrologic Cycle

    Science.gov (United States)

    Bosilovich, Michael G.; Schubert, Siegfried D.; Einaudi, Franco (Technical Monitor)

    2000-01-01

    Understanding of the local and remote sources of water vapor can be a valuable diagnostic in understanding the regional atmospheric hydrologic cycle. In the present study, we have implemented passive tracers as prognostic variables to follow water vapor evaporated in predetermined regions until the water tracer precipitates. The formulation of the sources and sinks of tracer water is generally proportional to the prognostic water vapor variable. Because all water has been accounted for in tracers, the water vapor variable provides the validation of the tracer water and the formulation of the sources and sinks. The tracers have been implemented in a GEOS General Circulation Model (GCM) simulation consisting of several summer periods to determine the source regions of precipitation for the United States and India. The recycling of water and interannual variability of the sources of water will be examined. Potential uses in GCM sensitivity studies, predictability studies and data assimilation will be discussed.

  13. Vapor hydrogen and oxygen isotopes reflect water of combustion in the urban atmosphere.

    Science.gov (United States)

    Gorski, Galen; Strong, Courtenay; Good, Stephen P; Bares, Ryan; Ehleringer, James R; Bowen, Gabriel J

    2015-03-17

    Anthropogenic modification of the water cycle involves a diversity of processes, many of which have been studied intensively using models and observations. Effective tools for measuring the contribution and fate of combustion-derived water vapor in the atmosphere are lacking, however, and this flux has received relatively little attention. We provide theoretical estimates and a first set of measurements demonstrating that water of combustion is characterized by a distinctive combination of H and O isotope ratios. We show that during periods of relatively low humidity and/or atmospheric stagnation, this isotopic signature can be used to quantify the concentration of water of combustion in the atmospheric boundary layer over Salt Lake City. Combustion-derived vapor concentrations vary between periods of atmospheric stratification and mixing, both on multiday and diurnal timescales, and respond over periods of hours to variations in surface emissions. Our estimates suggest that up to 13% of the boundary layer vapor during the period of study was derived from combustion sources, and both the temporal pattern and magnitude of this contribution were closely reproduced by an independent atmospheric model forced with a fossil fuel emissions data product. Our findings suggest potential for water vapor isotope ratio measurements to be used in conjunction with other tracers to refine the apportionment of urban emissions, and imply that water vapor emissions associated with combustion may be a significant component of the water budget of the urban boundary layer, with potential implications for urban climate, ecohydrology, and photochemistry.

  14. Preconditioning of the YSZ-NiO Fuel Cell Anode in Hydrogenous Atmospheres Containing Water Vapor

    Science.gov (United States)

    Vasyliv, Bogdan; Podhurska, Viktoriya; Ostash, Orest

    2017-04-01

    The YSZ-NiO ceramics for solid oxide fuel cells (SOFCs) anode have been investigated. A series of specimens were singly reduced in a hydrogenous atmosphere (Ar-5 vol% H2 mixture) at 600 °C under the pressure of 0.15 MPa or subjected to `reduction in the mixture-oxidation in air' (redox) cycling at 600 °C. The YSZ-Ni cermets formed in both treatment conditions were then aged in `water vapor in Ar-5 vol% H2 mixture' atmosphere at 600 °C under the pressure of 0.15 MPa. Additionally, the behaviour of the as-received material in this atmosphere was studied. It was revealed that small amount of water vapor in Ar-5 vol% H2 mixture (water vapor pressure below 0.03 MPa) does not affect the reduction of the nickel phase in the YSZ-NiO ceramics, but causes some changes in the YSZ-Ni cermet structure. In particular, nanopore growth in tiny Ni particles takes place. At higher concentration of water vapor in the mixture (water vapor pressure above 0.03-0.05 MPa), converse changes in the kinetics of reduction occur. The best physical and mechanical properties were revealed for the material treated by redox cycling after holding at 600 °C in water depleted gas mixture. The dual effect of water vapor on nickel-zirconia anode behaviour is discussed basing on scanning electron microscopy analysis data, material electrical conductivity, and strength.

  15. Stable isotopes in atmospheric water vapor and applications to the hydrologic cycle

    Science.gov (United States)

    Galewsky, Joseph; Steen-Larsen, Hans Christian; Field, Robert D.; Worden, John; Risi, Camille; Schneider, Matthias

    2016-12-01

    The measurement and simulation of water vapor isotopic composition has matured rapidly over the last decade, with long-term data sets and comprehensive modeling capabilities now available. Theories for water vapor isotopic composition have been developed by extending the theories that have been used for the isotopic composition of precipitation to include a more nuanced understanding of evaporation, large-scale mixing, deep convection, and kinetic fractionation. The technologies for in situ and remote sensing measurements of water vapor isotopic composition have developed especially rapidly over the last decade, with discrete water vapor sampling methods, based on mass spectroscopy, giving way to laser spectroscopic methods and satellite- and ground-based infrared absorption techniques. The simulation of water vapor isotopic composition has evolved from General Circulation Model (GCM) methods for simulating precipitation isotopic composition to sophisticated isotope-enabled microphysics schemes using higher-order moments for water and ice size distributions. The incorporation of isotopes into GCMs has enabled more detailed diagnostics of the water cycle and has led to improvements in its simulation. The combination of improved measurement and modeling of water vapor isotopic composition opens the door to new advances in our understanding of the atmospheric water cycle, in processes ranging from the marine boundary layer, through deep convection and tropospheric mixing, and into the water cycle of the stratosphere. Finally, studies of the processes governing modern water vapor isotopic composition provide an improved framework for the interpretation of paleoclimate proxy records of the hydrological cycle.

  16. Evidence of water vapor in excess of saturation in the atmosphere of Mars.

    Science.gov (United States)

    Maltagliati, L; Montmessin, F; Fedorova, A; Korablev, O; Forget, F; Bertaux, J-L

    2011-09-30

    The vertical distribution of water vapor is key to the study of Mars' hydrological cycle. To date, it has been explored mainly through global climate models because of a lack of direct measurements. However, these models assume the absence of supersaturation in the atmosphere of Mars. Here, we report observations made using the SPICAM (Spectroscopy for the Investigation of the Characteristics of the Atmosphere of Mars) instrument onboard Mars Express that provide evidence of the frequent presence of water vapor in excess of saturation, by an amount far surpassing that encountered in Earth's atmosphere. This result contradicts the widespread assumption that atmospheric water on Mars cannot exist in a supersaturated state, directly affecting our long-term representation of water transport, accumulation, escape, and chemistry on a global scale.

  17. The Effect of Water Vapor on the Thermal Decomposition of Pyrite in N2 Atmosphere

    Directory of Open Access Journals (Sweden)

    Nesrin BOYABAT

    2009-03-01

    Full Text Available In this study, the effect of water vapor on the thermal decomposition of pyrite mineral in nitrogen atmosphere has been investigated in a horizontal tube furnace. Temperature, time and water vapor concentration were used as experimental parameters. According to the data obtained at nitrogen/ water vapor environment, it was observed that the water vapor on the decomposition of pyrite increased the decomposition rate. The decomposition reaction is well represented by the "shrinking core" model and can be divided into two regions with different rate controlling step. The rate controlling steps were determined from the heat transfer through the gas film for the low conversions, while it was determined from the mass transfer through product ash layer for the high conversions. The activation energies of this gas and ash film mechanisms were found to be 77 and 81 kJ/mol-1, respectively.

  18. Constraining the Surficial Liquid Water and Resulting Atmospheric Water Vapor Abundance at Recurring Slope Lineae (RSL) Locations on Mars

    Science.gov (United States)

    Berdis, Jodi; Murphy, Jim; Wilson, Robert John

    2017-10-01

    Possible signatures of atmospheric water vapor arising from Martian Recurring Slope Lineae (RSLs) are investigated in this study. RSLs appear during local spring and summer on downward, equator-facing slopes at southern mid-latitudes (~31-52°S Stillman et al. 2014), and have been linked to liquid water which leaves behind streaks of briny material (McEwen et al. 2011, McEwen et al. 2014). Viking Orbiter Mars Atmospheric Water Detector (VO MAWD) and Mars Global Surveyor Thermal Emission Spectrometer (MGS TES) derived atmospheric water vapor abundance values are interrogated to determine whether four RSL locations at southern mid-latitudes (Palikir Crater, Hale Crater, Horowitz Crater, Coprates Chasma) exhibit episodic, enhanced local atmospheric water vapor abundance during southern spring and summer (Ls = 180-360°) when RSLs are observed to develop (Stillman et al. 2014, Ojha et al. 2015). Significant water vapor signals at these locations might reveal RSLs as the source of the enhanced water vapor. Detected atmospheric water vapor signals would expand upon current knowledge of RSLs, whereas non-detection could provide upper limits on RSL water source content. In order to assess how much surficial RSL water would be required to produce a detectable signal, we utilize the high spatial resolution Geophysical Fluid Dynamics Laboratory Mars Climate General Circulation Model to simulate the evaporation of RSL-producing surface water and quantify the magnitude and temporal duration of water vapor content that might be anticipated in response to inferred RSL surface water release. Finally, we will assess the ability of past and future orbiter-based instruments to detect such water vapor quantities.

  19. Alexandrite lidar for the atmospheric water vapor detection and development of powerful tunable sources in IR

    Science.gov (United States)

    Uchiumi, M.; Maeda, M.; Muraoka, K.; Uchino, O.

    1992-01-01

    New tunable solid-state lasers, such as alexandrite and Ti-sapphire lasers, provide a powerful technique to detect various molecules in the atmosphere whose absorption bands are in the infrared region. The differential absorption lidar (DIAL) system to measure the tropospheric water vapor has been investigated by many authors, in an early stage, by dye and ruby lasers. Using the alpha band of water vapor, the longest detection range can be obtained with high accuracy, and the alexandrite laser is the most suitable laser for this purpose. In this paper, we describe the detection of water vapor in the atmosphere by an alexandrite lidar, and the development of powerful tunable sources based on Raman lasers in the infrared region.

  20. Conversion function between the Linke turbidity and the atmospheric water vapor and aerosol content

    OpenAIRE

    Ineichen, Pierre

    2008-01-01

    This technical note presents a conversion function between the widely used Linke turbidity coefficient TL, the atmospheric water vapor and urban aerosol content. It takes into account the altitude of the application site. The function is based on radiative transfer calculations and validated with the help of an independent clear sky model. Its precision is around 0.12 units of TL.

  1. Preconditioning of the YSZ-NiO Fuel Cell Anode in Hydrogenous Atmospheres Containing Water Vapor.

    Science.gov (United States)

    Vasyliv, Bogdan; Podhurska, Viktoriya; Ostash, Orest

    2017-12-01

    The YSZ-NiO ceramics for solid oxide fuel cells (SOFCs) anode have been investigated. A series of specimens were singly reduced in a hydrogenous atmosphere (Ar-5 vol% H2 mixture) at 600 °C under the pressure of 0.15 MPa or subjected to 'reduction in the mixture-oxidation in air' (redox) cycling at 600 °C. The YSZ-Ni cermets formed in both treatment conditions were then aged in 'water vapor in Ar-5 vol% H2 mixture' atmosphere at 600 °C under the pressure of 0.15 MPa. Additionally, the behaviour of the as-received material in this atmosphere was studied. It was revealed that small amount of water vapor in Ar-5 vol% H2 mixture (water vapor pressure below 0.03 MPa) does not affect the reduction of the nickel phase in the YSZ-NiO ceramics, but causes some changes in the YSZ-Ni cermet structure. In particular, nanopore growth in tiny Ni particles takes place. At higher concentration of water vapor in the mixture (water vapor pressure above 0.03-0.05 MPa), converse changes in the kinetics of reduction occur. The best physical and mechanical properties were revealed for the material treated by redox cycling after holding at 600 °C in water depleted gas mixture. The dual effect of water vapor on nickel-zirconia anode behaviour is discussed basing on scanning electron microscopy analysis data, material electrical conductivity, and strength.

  2. An Analytical Formula for Potential Water Vapor in an Atmosphere of Constant Lapse Rate

    Directory of Open Access Journals (Sweden)

    Ali Varmaghani

    2012-01-01

    Full Text Available Accurate calculation of precipitable water vapor (PWV in the atmosphere has always been a matter of importance for meteorologists. Potential water vapor (POWV or maximum precipitable water vapor can be an appropriate base for estimation of probable maximum precipitation (PMP in an area, leading to probable maximum flood (PMF and flash flood management systems. PWV and POWV have miscellaneously been estimated by means of either discrete solutions such as tables, diagrams or empirical methods; however, there is no analytical formula for POWV even in a particular atmospherical condition. In this article, fundamental governing equations required for analytical calculation of POWV are first introduced. Then, it will be shown that this POWV calculation relies on a Riemann integral solution over a range of altitude whose integrand is merely a function of altitude. The solution of the integral gives rise to a series function which is bypassed by approximation of saturation vapor pressure in the range of -55 to 55 degrees Celsius, and an analytical formula for POWV in an atmosphere of constant lapse rate is proposed. In order to evaluate the accuracy of the suggested equation, exact calculations of saturated adiabatic lapse rate (SALR at different surface temperatures were performed. The formula was compared with both the diagrams from the US Weather Bureau and SALR. The results demonstrated unquestionable capability of analytical solutions and also equivalent functions.

  3. The influence of water vapor on atmospheric exchange measurements with an ICOS* based Laser absorption analyzer

    Science.gov (United States)

    Bunk, Rüdiger; Quan, Zhi; Wandel, Matthias; Yi, Zhigang; Bozem, Heiko; Kesselmeier, Jürgen

    2014-05-01

    Carbonyl sulfide and carbon monoxide are both atmospheric trace gases of high interest. Recent advances in the field of spectroscopy have enabled instruments that measure the concentration of the above and other trace gases very fast and with good precision. Increasing the effective path length by reflecting the light between two mirrors in a cavity, these instruments reach impressive sensitivities. Often it is possible to measure the concentration of more than one trace gas at the same time. The OCS/CO2 Analyzer by LGR (Los Gatos Research, Inc.) measures the concentration of water vapor [H2O], carbonyl sulfide [COS], carbon dioxide [CO2] and carbon monoxide [CO] simultaneously. For that the cavity is saturated with light, than the attenuation of light is measured as in standard absorption spectroscopy. The instrument proved to be very fast with good precision and to be able to detect even very low concentrations, especially for COS (as low as 30ppt in the case of COS). However, we observed a rather strong cross sensitivity to water vapor. Altering the water vapor content of the sampled air with two different methods led to a change in the perceived concentration of COS, CO and CO2. This proved especially problematic for enclosure (cuvette) measurements, where the concentrations of one of the above species in an empty cuvette are compared to the concentration of another cuvette containing a plant whose exchange of trace gases with the atmosphere is of interest. There, the plants transpiration leads to a large difference in water vapor content between the cuvettes and that in turn produces artifacts in the concentration differences between the cuvettes for the other above mentioned trace gases. For CO, simultaneous measurement with a UV-Emission Analyzer (AL 5002, Aerolaser) and the COS/CO Analyzer showed good agreement of perceived concentrations as long as the sample gas was dry and an increasing difference in perceived concentration when the sample gas was

  4. Tracking atmospheric boundary layer dynamics with water vapor D-excess observations

    KAUST Repository

    Parkes, Stephen

    2015-04-01

    Stable isotope water vapor observations present a history of hydrological processes that have impacted on an air mass. Consequently, there is scope to improve our knowledge of how different processes impact on humidity budgets by determining the isotopic end members of these processes and combining them with in-situ water vapor measurements. These in-situ datasets are still rare and cover a limited geographical expanse, so expanding the available data can improve our ability to define isotopic end members and knowledge about atmospheric humidity dynamics. Using data collected from an intensive field campaign across a semi-arid grassland site in eastern Australia, we combine multiple methods including in-situ stable isotope observations to study humidity dynamics associated with the growth and decay of the atmospheric boundary layer and the stable nocturnal boundary layer. The deuterium-excess (D-excess) in water vapor is traditionally thought to reflect the sea surface temperature and relative humidity at the point of evaporation over the oceans. However, a number of recent studies suggest that land-atmosphere interactions are also important in setting the D-excess of water vapor. These studies have shown a highly robust diurnal cycle for the D-excess over a range of sites that could be exploited to better understand variations in atmospheric humidity associated with boundary layer dynamics. In this study we use surface radon concentrations as a tracer of surface layer dynamics and combine these with the D-excess observations. The radon concentrations showed an overall trend that was inversely proportional to the D-excess, with early morning entrainment of air from the residual layer of the previous day both diluting the radon concentration and increasing the D-excess, followed by accumulation of radon at the surface and a decrease in the D-excess as the stable nocturnal layer developed in the late afternoon and early evening. The stable nocturnal boundary layer

  5. LBA-ECO CD-02 Oxygen Isotopes of Plant Tissue Water and Atmospheric Water Vapor

    Data.gov (United States)

    National Aeronautics and Space Administration — ABSTRACT: This data set reports the oxygen isotope signatures of water extracted from plant tissue (xylem from the stems and leaf tissue) and of atmospheric water...

  6. Algorithm for Recovery of Integrated Water Vapor Content in the Atmosphere over Land Surfaces Based on Satellite Spectroradiometer Data

    Science.gov (United States)

    Lisenko, S. A.

    2017-05-01

    An algorithm is proposed for making charts of the distribution of water vapor in the atmosphere based on multispectral images of the earth by the Ocean and Land Color Instrument (OLCI) on board of the European research satellite Sentinel-3. The algorithm is based on multiple regression fits of the spectral brightness coefficients at the upper boundary of the atmosphere, the geometric parameters of the satellite location (solar and viewing angles), and the total water vapor content in the atmosphere. A regression equation is derived from experimental data on the variation in the optical characteristics of the atmosphere and underlying surface, together with Monte-Carlo calculations of the radiative transfer characteristics. The equation includes the brightness coefficients in the near IR channels of the OLCI for the absorption bands of water vapor and oxygen, as well as for the transparency windows of the atmosphere. Together these make it possible to eliminate the effect of the reflection spectrum of the underlying surface and air pressure on the accuracy of the measurements. The algorithm is tested using data from a prototype OLCI, the medium resolution imaging spectrometer (MERIS). A sample chart of the distribution of water vapor in the atmosphere over Eastern Europe is constructed without using subsatellite data and digital models of the surface relief. The water vapor contents in the atmosphere determined using MERIS images and data provided by earthbound measurements with the aerosol robotic network (AERONET) are compared with a mean square deviation of 1.24 kg/m2.

  7. Enhancing our Understanding of the Arctic Atmospheric Hydrological Cycle using Observations from an International Arctic Water Vapor Isotope Network

    Science.gov (United States)

    Masson-Delmotte, V.; Steen-Larsen, H. C.; Werner, M.

    2014-12-01

    Due to the role of water vapor and clouds in positive feedback mechanisms, water vapor is a key player in the future of Arctic climate. Ecosystems and human societies are vulnerable to climate change through even minor changes in precipitation patterns, including the occurrence of extreme events. It is therefore essential to monitor, understand and model correctly the mechanisms of transport of moisture, at the regional scale. Water isotopes - the relative abundance of heavy and light water in the atmosphere - hold the key to understanding the physical processes influencing future Arctic climate. Water isotope observations in the atmosphere are a modern analog to the Rosetta Stone for understanding the processes involved in evaporation, moisture transport, cloud formation and to track moisture origin. Indeed, technological progress now allows continuous, in situ or remote sensing monitoring of water isotopic composition. In parallel, a growing number of atmospheric circulation models are equipped with the explicit modeling of water stable isotopes, allowing evaluation at the process scale. We present here data obtained through national or bi-national initiatives from stations onboard an icebreaker and land based stations in Greenland, Iceland, Svalbard, and Siberia - together forming an emerging international Arctic water vapor isotope network. Using water tagging and back trajectories we show water vapor of Arctic origin to have a high d-excess fingerprint. This show the potential of using water vapor isotopes as tracer for changes in the Arctic hydrological cycle. Using the network of monitoring stations we quantify using the isotopes advection of air masses and the key processes affecting the water vapor en-route between stations. We have successfully used the obtained atmospheric water vapor isotope observations to benchmark isotope-enabled general circulation models. This comparison allows us to address key processes of the atmospheric hydrological cycle for

  8. Atmospheric absorption model for dry air and water vapor at microwave frequencies below 100 GHz derived from spaceborne radiometer observations

    Science.gov (United States)

    Wentz, Frank J.; Meissner, Thomas

    2016-05-01

    The Liebe and Rosenkranz atmospheric absorption models for dry air and water vapor below 100 GHz are refined based on an analysis of antenna temperature (TA) measurements taken by the Global Precipitation Measurement Microwave Imager (GMI) in the frequency range 10.7 to 89.0 GHz. The GMI TA measurements are compared to the TA predicted by a radiative transfer model (RTM), which incorporates both the atmospheric absorption model and a model for the emission and reflection from a rough-ocean surface. The inputs for the RTM are the geophysical retrievals of wind speed, columnar water vapor, and columnar cloud liquid water obtained from the satellite radiometer WindSat. The Liebe and Rosenkranz absorption models are adjusted to achieve consistency with the RTM. The vapor continuum is decreased by 3% to 10%, depending on vapor. To accomplish this, the foreign-broadening part is increased by 10%, and the self-broadening part is decreased by about 40% at the higher frequencies. In addition, the strength of the water vapor line is increased by 1%, and the shape of the line at low frequencies is modified. The dry air absorption is increased, with the increase being a maximum of 20% at the 89 GHz, the highest frequency considered here. The nonresonant oxygen absorption is increased by about 6%. In addition to the RTM comparisons, our results are supported by a comparison between columnar water vapor retrievals from 12 satellite microwave radiometers and GPS-retrieved water vapor values.

  9. Where do winds come from? A new theory on how water vapor condensation influences atmospheric pressure and dynamics

    CERN Document Server

    Makarieva, A M; Sheil, D; Nobre, A D; Li, B -L

    2010-01-01

    Phase transitions of atmospheric water play a ubiquitous role in the Earth's climate system, but their direct impact on atmospheric dynamics has escaped wide attention. Here we examine and advance a theory as to how condensation influences atmospheric pressure through the mass removal of water from the gas phase with a simultaneous account of the latent heat release. Building from the fundamental physical principles we show that condensation is associated with a decline in air pressure in the lower atmosphere. This decline occurs up to a certain height, which ranges from 3 to 4 km for surface temperatures from 10 to 30 deg C. We then estimate the horizontal pressure differences associated with water vapor condensation and find that these are comparable in magnitude with the pressure differences driving observed circulation patterns. The water vapor delivered to the atmosphere via evaporation represents a store of potential energy available to accelerate air and thus drive winds. Our estimates suggest that the...

  10. Adsorption tests of water vapor on synthetic zeolites for an atmospheric detritiation dryer

    Energy Technology Data Exchange (ETDEWEB)

    Kim, K.R. [Korea Atomic Energy Research Institute, 150 Deokjin-dong, Yuseong-gu, Daejeon 305-353 (Korea, Republic of)]. E-mail: krkim1@kaeri.re.kr; Lee, M.S. [Korea Atomic Energy Research Institute, 150 Deokjin-dong, Yuseong-gu, Daejeon 305-353 (Korea, Republic of); Paek, S. [Korea Atomic Energy Research Institute, 150 Deokjin-dong, Yuseong-gu, Daejeon 305-353 (Korea, Republic of); Yim, S.P. [Korea Atomic Energy Research Institute, 150 Deokjin-dong, Yuseong-gu, Daejeon 305-353 (Korea, Republic of); Ahn, D.H. [Korea Atomic Energy Research Institute, 150 Deokjin-dong, Yuseong-gu, Daejeon 305-353 (Korea, Republic of); Chung, H. [Korea Atomic Energy Research Institute, 150 Deokjin-dong, Yuseong-gu, Daejeon 305-353 (Korea, Republic of)

    2007-08-15

    Tritiated hydrogen and hydrocarbon are usually oxidized to a tritiated water vapor to make the tritium adsorbable and easy to treat. The adsorption system as a subsequent process plays an important role in a tritium recovery and its performance affects the overall detritiation efficiency significantly. In order to quantify an adsorbent's utilization and its dynamic capacity against an inlet humidity and a flow rate, a series of quantitative tests based on the breakthrough behavior were carried out in an isothermal fixed bed of synthetic zeolites such as molecular sieve 4A, 5A, 13X and mordenite. The amount of water vapor breaking during the adsorption was estimated to provide a breakthrough capacity at the various inlet flow rates and humidity conditions. The molecular sieve 13X exhibited a better adsorption performance at a given bed height. The existence of CO{sub 2} in a humid atmosphere had a minor effect on the net adsorption capacity and the hydrogen isotopic water (HDO) in the elution stream showed a delayed behavior during a thermal desorption.

  11. Influence of long-range transboundary transport on atmospheric water vapor mercury collected at the largest city of Tibet

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Jie [Key Laboratory of Tibetan Environment Changes and Land Surface Processes, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing 100101 (China); CAS Center for Excellence in Tibetan Plateau Earth Sciences, Chinese Academy of Sciences, Beijing 100101 (China); Laboratory of Green Chemistry, Lappeenranta University of Technology, Sammonkatu 12, Mikkeli FI 50130 (Finland); Kang, Shichang, E-mail: shichang.kang@lzb.ac.cn [State Key Laboratory of Cryospheric Sciences, Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou 730000 (China); CAS Center for Excellence in Tibetan Plateau Earth Sciences, Chinese Academy of Sciences, Beijing 100101 (China); Tian, Lide [Key Laboratory of Tibetan Environment Changes and Land Surface Processes, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing 100101 (China); CAS Center for Excellence in Tibetan Plateau Earth Sciences, Chinese Academy of Sciences, Beijing 100101 (China); Guo, Junming [Key Laboratory of Tibetan Environment Changes and Land Surface Processes, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing 100101 (China); Graduate University of the Chinese Academy of Sciences, Beijing 100049 (China); Zhang, Qianggong; Cong, Zhiyuan [Key Laboratory of Tibetan Environment Changes and Land Surface Processes, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing 100101 (China); CAS Center for Excellence in Tibetan Plateau Earth Sciences, Chinese Academy of Sciences, Beijing 100101 (China); Sillanpää, Mika [Laboratory of Green Chemistry, Lappeenranta University of Technology, Sammonkatu 12, Mikkeli FI 50130 (Finland); and others

    2016-10-01

    Monsoon circulation is an important process that affects long-range transboundary transport of anthropogenic contaminants such as mercury (Hg). During the Indian monsoon season of 2013, a total of 92 and 26 atmospheric water vapor samples were collected at Lhasa, the largest city of the Tibet, for Hg and major ions analysis, respectively. The relatively low pH/high electronic conductivity values, together with the fact that NH{sub 4}{sup +} in atmospheric water vapor was even higher than that determined in precipitation of Lhasa, indicated the effects of anthropogenic perturbations through long-range transboundary atmospheric transport. Concentrations of Hg in atmospheric water vapor ranged from 2.5 to 73.7 ng L{sup −1}, with an average of 12.5 ng L{sup −1}. The elevated Hg and major ions concentrations, and electronic conductivity values were generally associated with weak acidic samples, and Hg mainly loaded with anthropogenic ions such as NH{sub 4}{sup +}. The results of principal component analysis and trajectory analysis suggested that anthropogenic emissions from the Indian subcontinent may have largely contributed to the determined Hg in atmospheric water vapor. Furthermore, our study reconfirmed that below-cloud scavenging contribution was significant for precipitation Hg in Lhasa, and evaluated that on average 74.1% of the Hg in precipitation could be accounted for by below-cloud scavenging. - Highlights: • The low pH/high electronic conductivity was found in atmospheric water vapor. • Anthropogenic NH{sub 4}{sup +} was higher than that determined in precipitation of Lhasa. • Elevated Hg and major ions levels were usually associated with weak acidic samples. • Hg in atmospheric water vapor was largely influenced by transboundary transport. • Below-cloud scavenging accounted for most Hg in precipitation.

  12. Investigation of water adsorption and hygroscopicity of atmospherically relevant particles using a commercial vapor sorption analyzer

    Science.gov (United States)

    Gu, Wenjun; Li, Yongjie; Zhu, Jianxi; Jia, Xiaohong; Lin, Qinhao; Zhang, Guohua; Ding, Xiang; Song, Wei; Bi, Xinhui; Wang, Xinming; Tang, Mingjin

    2017-10-01

    Water adsorption and hygroscopicity are among the most important physicochemical properties of aerosol particles, largely determining their impacts on atmospheric chemistry, radiative forcing, and climate. Measurements of water adsorption and hygroscopicity of nonspherical particles under subsaturated conditions are nontrivial because many widely used techniques require the assumption of particle sphericity. In this work we describe a method to directly quantify water adsorption and mass hygroscopic growth of atmospheric particles for temperature in the range of 5-30 °C, using a commercial vapor sorption analyzer. A detailed description of instrumental configuration and experimental procedures, including relative humidity (RH) calibration, is provided first. It is then demonstrated that for (NH4)2SO4 and NaCl, deliquescence relative humidities and mass hygroscopic growth factors measured using this method show good agreements with experimental and/or theoretical data from literature. To illustrate its ability to measure water uptake by particles with low hygroscopicity, we used this instrument to investigate water adsorption by CaSO4 ṡ 2H2O as a function of RH at 25 °C. The mass hygroscopic growth factor of CaSO4 ṡ 2H2O at 95 % RH, relative to that under dry conditions (RH < 1 %), was determined to be (0.450±0.004) % (1σ). In addition, it is shown that this instrument can reliably measure a relative mass change of 0.025 %. Overall, we have demonstrated that this commercial instrument provides a simple, sensitive, and robust method to investigate water adsorption and hygroscopicity of atmospheric particles.

  13. Comparison of Radiophysical and Optical Infrared Ground-Based Methods for Measuring Integrated Content of Atmospheric Water Vapor in Atmosphere

    Science.gov (United States)

    Ionov, D. V.; Kalinnikov, V. V.; Timofeyev, Yu. M.; Zaitsev, N. A.; Virolainen, Y. A.; Kostsov, V. S.; Poberovskii, A. V.

    2017-09-01

    By virtue of their all-weather capabilities, the radiophysical atmospheric sensing methods allow one, in particular, to perform continuous observations of variations in the atmospheric content of water vapor being the most important natural greenhouse gas. The measurement station of St. Petersburg State University at Peterhof (59.88° N, 29.83° E) runs a number of ground-based instruments to determine total water-vapor content (TWVC) in the atmosphere. During a year period from September 2014 to September 2015, the TWVC was synchronously measured by two radiophysical methods, namely, the microwave and radio-refraction techniques, as well as the optical infrared method. Comparisons show that the average systematic and random discrepancies among the three methods amount to 0.3-0.5 kg/m2 (3-7%) and 0.4-0.6 kg/m2 (8-11%), respectively. The maximum relative differences (up to 20%) among the results of different-type measurements are observed for very small TWVC values (below 5 kg/m2). Empirical estimates of the random errors of the methods were 0.5, 0.3, and 0.3 kg/m2 for the radio-refraction, microwave, and infrared methods, respectively. The results of the TWVC measuring by the radio-refraction and microwave methods are in good agreement and yield greater values than those obtained by the optical method. The obtained discrepancies in the TWVC estimates are small compared with the published results of similar comparisons, which can, in particular, be attributed to the high spatiotemporal matching of various measurements.

  14. Airborne Lidar for Simultaneous Measurement of Column CO2 and Water Vapor in the Atmosphere

    Science.gov (United States)

    Singh, Upendra N.; Petros, Mulugeta; Refaat, Tamer F.; Antill, Charles W.; Remus, Ruben; Yu, Jirong

    2016-01-01

    The 2-micron wavelength region is suitable for atmospheric carbon dioxide (CO2) measurements due to the existence of distinct absorption feathers for the gas at this particular wavelength. For more than 20 years, researchers at NASA Langley Research Center (LaRC) have developed several high-energy and high repetition rate 2-micron pulsed lasers. This paper will provide status and details of an airborne 2-micron triple-pulse integrated path differential absorption (IPDA) lidar. The development of this active optical remote sensing IPDA instrument is targeted for measuring both CO2 and water vapor (H2O) in the atmosphere from an airborne platform. This presentation will focus on the advancement of the 2-micron triple-pulse IPDA lidar development. Updates on the state-of-the-art triple-pulse laser transmitter will be presented including the status of seed laser locking, wavelength control, receiver telescope, detection system and data acquisition. Future plans for the IPDA lidar system for ground integration, testing and flight validation will also be presented.

  15. Airborne lidar for simultaneous measurement of column CO2 and water vapor in the atmosphere

    Science.gov (United States)

    Singh, Upendra N.; Petros, Mulugeta; Refaat, Tamer F.; Antill, Charles W.; Remus, Ruben; Yu, Jirong

    2016-10-01

    The 2-micron wavelength region is suitable for atmospheric carbon dioxide (CO2) measurements due to the existence of distinct absorption feathers for the gas at this particular wavelength. For more than 20 years, researchers at NASA Langley Research Center (LaRC) have developed several high-energy and high repetition rate 2-micron pulsed lasers. This paper will provide status and details of an airborne 2-micron triple-pulse integrated path differential absorption (IPDA) lidar. The development of this active optical remote sensing IPDA instrument is targeted for measuring both CO2 and water vapor (H2O) in the atmosphere from an airborne platform. This presentation will focus on the advancement of the 2-micron triple-pulse IPDA lidar development. Updates on the state-of-the-art triple-pulse laser transmitter will be presented including the status of seed laser locking, wavelength control, receiver telescope, detection system and data acquisition. Future plans for the IPDA lidar system for ground integration, testing and flight validation will also be presented.

  16. Water vapor in the middle atmosphere of Mars during the 2007 global dust storm

    Science.gov (United States)

    Fedorova, Anna; Bertaux, Jean-Loup; Betsis, Daria; Montmessin, Franck; Korablev, Oleg; Maltagliati, Luca; Clarke, John

    2018-01-01

    Recent observations of the Martian hydrogen corona in the UV H Ly-alpha emission by the Hubble Space Telescope (HST) (Clarke et al., 2014) and the SPICAM UV spectrometer on Mars Express (Chaffin et al., 2014) reported its rapid change by an order of magnitude over a short few months period in 2007 (MY28), which is inconsistent with the existing models. One proposed explanation of the observed increase of the coronal emission is that during the global dust storm water vapor from the lower atmosphere can be transported to higher altitudes, where its photodissociation rate by near-UV sunlight increases, providing an additional source of hydrogen for the upper atmosphere. In this work we study the water vapor vertical distribution in the middle atmosphere of Mars during the 2007 global dust storm based on solar occultation measurements by the SPICAM IR spectrometer onboard the Mars-Express spacecraft. The vertical profiles of H2O density and mixing ratio have been obtained for solar longitudes Ls = 255°-300° in MY28. In the Northern hemisphere from Ls = 268° to Ls = 285° the H2O density at altitudes of 60-80 km increased by an order of magnitude. During the dust storm the profiles extended up to 80 km, with an H2O density exceeding 1010 molecules/cm3 (mixing ratio ≥200 ppm). Two maxima of the H2O density were detected. The largest H2O densities observed at latitudes higher than 60°N, over Ls = 269°-275°, do not directly correlate with the aerosol loading and likely relate to the downwelling branch of the meridional circulation that was intensified during the dust storm, and transported water from the Southern hemisphere to high northern latitudes. The second smaller maximum coincides with the high dust loading at middle northern latitudes. The comparison with geographically close observations in the quiet Mars year MY32, when the H2O content in the Northern hemisphere did not exceed 2 × 1010 molecules/cm3 and 50 ppm at 60 km, showed that the global dust storm

  17. Where do winds come from? A new theory on how water vapor condensation influences atmospheric pressure and dynamics

    Directory of Open Access Journals (Sweden)

    A. M. Makarieva

    2013-01-01

    Full Text Available Phase transitions of atmospheric water play a ubiquitous role in the Earth's climate system, but their direct impact on atmospheric dynamics has escaped wide attention. Here we examine and advance a theory as to how condensation influences atmospheric pressure through the mass removal of water from the gas phase with a simultaneous account of the latent heat release. Building from fundamental physical principles we show that condensation is associated with a decline in air pressure in the lower atmosphere. This decline occurs up to a certain height, which ranges from 3 to 4 km for surface temperatures from 10 to 30 °C. We then estimate the horizontal pressure differences associated with water vapor condensation and find that these are comparable in magnitude with the pressure differences driving observed circulation patterns. The water vapor delivered to the atmosphere via evaporation represents a store of potential energy available to accelerate air and thus drive winds. Our estimates suggest that the global mean power at which this potential energy is released by condensation is around one per cent of the global solar power – this is similar to the known stationary dissipative power of general atmospheric circulation. We conclude that condensation and evaporation merit attention as major, if previously overlooked, factors in driving atmospheric dynamics.

  18. Increasing vertical resolution of three-dimensional atmospheric water vapor retrievals using a network of scanning compact microwave radiometers

    Science.gov (United States)

    Sahoo, Swaroop

    2011-12-01

    The thermodynamic properties of the troposphere, in particular water vapor content and temperature, change in response to physical mechanisms, including frictional drag, evaporation, transpiration, heat transfer and flow modification due to terrain. The planetary boundary layer (PBL) is characterized by a high rate of change in its thermodynamic state on time scales of typically less than one hour. Large horizontal gradients in vertical wind speed and steep vertical gradients in water vapor and temperature in the PBL are associated with high-impact weather. Observation of these gradients in the PBL with high vertical resolution and accuracy is important for improvement of weather prediction. Satellite remote sensing in the visible, infrared and microwave provide qualitative and quantitative measurements of many atmospheric properties, including cloud cover, precipitation, liquid water content and precipitable water vapor in the upper troposphere. However, the ability to characterize the thermodynamic properties of the PBL is limited by the confounding factors of ground emission in microwave channels and of cloud cover in visible and IR channels. Ground-based microwave radiometers are routinely used to measure thermodynamic profiles. The vertical resolution of such profiles retrieved from radiometric brightness temperatures depends on the number and choice of frequency channels, the scanning strategy and the accuracy of brightness temperature measurements. In the standard technique, which uses brightness temperatures from vertically pointing radiometers, the vertical resolution of the retrieved water vapor profile is similar to or larger than the altitude at which retrievals are performed. This study focuses on the improvement of the vertical resolution of water vapor retrievals by including scanning measurements at a variety of elevation angles. Elevation angle scanning increases the path length of the atmospheric emission, thus improving the signal-to-noise ratio

  19. Diurnal variation of atmospheric water vapor at Gale crater: Analysis from ground-based measurements

    Science.gov (United States)

    Martinez, German; McConnochie, Timothy; Renno, Nilton; Meslin, Pierre-Yves; Fischer, Erik; Vicente-Retortillo, Alvaro; Borlina, Caue; Kemppinen, Osku; Genzer, Maria; Harri, Ari-Matti; de la Torre-Juárez, Manuel; Zorzano, Mari-Paz; Martin-Torres, Javier; Bridges, Nathan; Maurice, Sylvestre; Gasnault, Olivier; Gomez-Elvira, Javier; Wiens, Roger

    2016-04-01

    We analyze measurements obtained by Curiosity's Rover Environmental Monitoring Station (REMS) and ChemCam (CCAM) instruments to shed light on the hydrological cycle at Gale crater. In particular, we use nighttime REMS measurements taken when the atmospheric volume mixing ratio (VMR) and its uncertainty are the lowest (between 05:00 and 06:00 LTST) [1], and daytime CCAM passive sky measurements taken when the VMR is expected to be the highest (between 10:00 and 14:00 LTST) [2]. VMR is calculated from simultaneous REMS measurements of pressure (P), temperature (T) and relative humidity (RH) at 1.6 m (VMR is defined as RH×es(T)/P , where es is the saturation water vapor pressure over ice). The REMS relative humidity sensor has recently been recalibrated (June 2015), providing RH values slightly lower than those in the previous calibration (Dec 2014). The full diurnal cycle of VMR cannot be analyzed using only REMS data because the uncertainty in daytime VMR derived from REMS measurements is extremely high. Daytime VMR is inferred by fitting the output of a multiple-scattering discrete-ordinates radiative transfer model to CCAM passive sky observations [3]. CCAM makes these observations predominately in the vicinity of 11:00 - 12:00 LTST, but occasionally in the early morning near 08:00 LTST. We find that throughout the Martian year, the daytime VMR is higher than at night, with a maximum day-to-night ratio of about 6 during winter. Various processes might explain the differences between nighttime REMS and daytime CCAM VMR values. Potential explanations include: (i) surface nighttime frost formation followed by daytime sublimation [1], (ii) surface nighttime adsorption of water vapor by the regolith followed by daytime desorption and (iii) large scale circulations changing vertical H2O profiles at different times of the year. Potential formation of surface frost can only occur in late fall and winter [1], coinciding with the time when the diurnal amplitude of the near

  20. Ultra Narrowband Optical Filters for Water Vapor Differential Absorption Lidar (DIAL) Atmospheric Measurements

    Science.gov (United States)

    Stenholm, Ingrid; DeYoung, Russell J.

    2001-01-01

    Differential absorption lidar (DIAL) systems are being deployed to make vertical profile measurements of atmospheric water vapor from ground and airborne platforms. One goal of this work is to improve the technology of such DIAL systems that they could be deployed on space-based platforms. Since background radiation reduces system performance, it is important to reduce it. One way to reduce it is to narrow the bandwidth of the optical receiver system. However, since the DIAL technique uses two or more wavelengths, in this case separated by 0.1 nm, a fixed-wavelength narrowband filter that would encompass both wavelengths would be broader than required for each line, approximately 0.02 nm. The approach employed in this project is to use a pair of tunable narrowband reflective fiber Bragg gratings. The Bragg gratings are germanium-doped silica core fiber that is exposed to ultraviolet radiation to produce index-of-refraction changes along the length of the fiber. The gratings can be tuned by stretching. The backscattered laser radiation is transmitted through an optical circulator to the gratings, reflected back to the optical circulator by one of the gratings, and then sent to a photodiode. The filter reflectivities were >90 percent, and the overall system efficiency was 30 percent.

  1. An all-fiber spectroscopic Raman lidar system for atmospheric water vapor measurements

    Science.gov (United States)

    Wang, Yufeng; Zhao, Meina; Fu, Qiang; Li, Zhao; Di, Huige; Wang, Li; Hua, Dengxin

    2016-01-01

    Aimed to establish a Raman lidar system with high-reliability and high anti-interference performance, an newly all-fiber spectroscopic Raman lidar system was proposed for atmospheric water vapor measurement, in which optical fiber couplers, fiber band-width filters and fiber F-P filters constitute the all-fiber spectroscopic system. On the basis of the design of fiber F-P filters and its transmission analysis, the series connection of optical fiber coupler is designed as fiber optics splitter, which is not only to obtain fiber coupling of the input and output of lidar returns, and also to achieve the optimal energy output ratio at three fiber channels. Furthermore, fiber band-width filters are proposed to replace the dichroic mirrors, and the structure of fiber band-width filters and fiber F-P filters is to constitute the secondary cascade filter system, achieving the fine extraction of interested spectrum and high rejection rate to elastic scattering signals. Preliminary test results indicated that, the energy at the three output ports is %sim;5: 2.5: 2.5, and the two fiber band-width filters are provided with the central wavelength of 606nm and 660nm, the bandwidth of 20nm, and the out of band inhibition of >0.5%, which met the design requirements. The design and results will provide a reliable basis for the integration and experiment of the subsequent all-fiber spectroscopic system.

  2. Measurements of the vertical profile of water vapor abundance in the Martian atmosphere from Mars Observer

    Science.gov (United States)

    Schofield, J. T.; Mccleese, Daniel J.

    1988-01-01

    An analysis is presented of the Pressure Modulator Infrared Radiometer (PMIRR) capabilities along with how the vertical profiles of water vapor will be obtained. The PMIRR will employ filter and pressure modulation radiometry using nine spectral channels, in both limb scanning and nadir sounding modes, to obtain daily, global maps of temperature, dust extinction, condensate extinction, and water vapor mixing ratio profiles as a function of pressure to half scale height or 5 km vertical resolution. Surface thermal properties will also be mapped, and the polar radiactive balance will be monitored.

  3. Water vaporization on Ceres

    Science.gov (United States)

    A'Hearn, Michael F.; Feldman, Paul D.

    1992-01-01

    A search is presently conducted for OH generated by the photodissociation of atmospheric water vapor in long-exposure IUE spectra of the region around Ceres. A statistically significant detection of OH is noted in an exposure off the northern limb of Ceres after perihelion. The amount of OH is consistent with a polar cap that might be replenished during winter by subsurface percolation, but which dissipates in summer.

  4. Estimation of the Total Atmospheric Water Vapor Content and Land Surface Temperature Based on AATSR Thermal Data

    Science.gov (United States)

    Zhang, Tangtang; Wen, Jun; van der Velde, Rogier; Meng, Xianhong; Li, Zhenchao; Liu, Yuanyong; Liu, Rong

    2008-01-01

    The total atmospheric water vapor content (TAWV) and land surface temperature (LST) play important roles in meteorology, hydrology, ecology and some other disciplines. In this paper, the ENVISAT/AATSR (The Advanced Along-Track Scanning Radiometer) thermal data are used to estimate the TAWV and LST over the Loess Plateau in China by using a practical split window algorithm. The distribution of the TAWV is accord with that of the MODIS TAWV products, which indicates that the estimation of the total atmospheric water vapor content is reliable. Validations of the LST by comparing with the ground measurements indicate that the maximum absolute derivation, the maximum relative error and the average relative error is 4.0K, 11.8% and 5.0% respectively, which shows that the retrievals are believable; this algorithm can provide a new way to estimate the LST from AATSR data. PMID:27879795

  5. Estimating trends in atmospheric water vapor and temperature time series over Germany

    Science.gov (United States)

    Alshawaf, Fadwa; Balidakis, Kyriakos; Dick, Galina; Heise, Stefan; Wickert, Jens

    2017-08-01

    Ground-based GNSS (Global Navigation Satellite System) has efficiently been used since the 1990s as a meteorological observing system. Recently scientists have used GNSS time series of precipitable water vapor (PWV) for climate research. In this work, we compare the temporal trends estimated from GNSS time series with those estimated from European Center for Medium-Range Weather Forecasts (ECMWF) reanalysis (ERA-Interim) data and meteorological measurements. We aim to evaluate climate evolution in Germany by monitoring different atmospheric variables such as temperature and PWV. PWV time series were obtained by three methods: (1) estimated from ground-based GNSS observations using the method of precise point positioning, (2) inferred from ERA-Interim reanalysis data, and (3) determined based on daily in situ measurements of temperature and relative humidity. The other relevant atmospheric parameters are available from surface measurements of meteorological stations or derived from ERA-Interim. The trends are estimated using two methods: the first applies least squares to deseasonalized time series and the second uses the Theil-Sen estimator. The trends estimated at 113 GNSS sites, with 10 to 19 years temporal coverage, vary between -1.5 and 2.3 mm decade-1 with standard deviations below 0.25 mm decade-1. These results were validated by estimating the trends from ERA-Interim data over the same time windows, which show similar values. These values of the trend depend on the length and the variations of the time series. Therefore, to give a mean value of the PWV trend over Germany, we estimated the trends using ERA-Interim spanning from 1991 to 2016 (26 years) at 227 synoptic stations over Germany. The ERA-Interim data show positive PWV trends of 0.33 ± 0.06 mm decade-1 with standard errors below 0.03 mm decade-1. The increment in PWV varies between 4.5 and 6.5 % per degree Celsius rise in temperature, which is comparable to the theoretical rate of the Clausius

  6. Water vapor mapping by fusing InSAR and GNSS remote sensing data and atmospheric simulations

    OpenAIRE

    Alshawaf, F.; Fersch, B.; Hinz, S; Kunstmann, H.; Mayer, M; Meyer, F.J.

    2015-01-01

    Data fusion aims at integrating multiple data sources that can be redundant or complementary to produce complete, accurate information of the parameter of interest. In this work, data fusion of precipitable water vapor (PWV) estimated from remote sensing observations and data from the Weather Research and Forecasting (WRF) modeling system is applied to provide complete, accurate grids of PWV. Our goal is to infer spatially continuous, prec...

  7. Validation of Atmospheric Water Vapor Derived from Ship-Borne GPS Measurements in the Chinese Bohai Sea

    Directory of Open Access Journals (Sweden)

    Shi-Jie Fan

    2016-04-01

    Full Text Available Atmospheric water vapor (AWV was investigated for the first time in the Chinese Bohai Sea using a Global Positioning System (GPS receiver aboard a lightweight (300-ton ship. An experiment was conducted to retrieve the AWV using the state-of-the-art GPS precise point positioning (PPP technique. The effects of atmospheric weighted mean temperature model and zenith wet delay constraint on GPS AWV estimates were discussed in the PPP estimation system. The GPS-derived precipitable water vapor (PWV and slant-path water vapor (SWV were assessed by comparing with those derived from the Fifth Generation NCAR/Penn State Mesoscale Model (MM5. The results showed the PWV and SWV differences between those derived from both GPS and MM5 are 1.5 mm root mean square (RMS with a bias of 0.2 and 3.9 mm RMS with a bias of -0.7 mm respectively. These good agreements indicate that the GPS-derived AWV in dynamic environments has a comparable accuracy with that of the MM5 model. This suggests that high accuracy and high spatio-temporal resolution humidity fields can be obtained using GPS in the Chinese Bohai Sea, which offers significant potential for meteorological applications and climate studies in this region.

  8. Transient desorption of water vapor - A potential source of error in upper atmosphere rocket experiments

    Science.gov (United States)

    Kendall, B. R. F.; Weeks, J. O.

    1974-01-01

    Results of measurements of the outgassing rates of samples of materials and surface finishes used on the outer skins of rocket-borne experiment packages in simulated rocket ascents. The results showed outgassing rates for anodized aluminum in the second minute of flight which are two to three orders of magnitude higher than those given in typical tables of outgassing rates. The measured rates for aluminum with chromate conversion surface coatings were also abnormally high. These abnormally high initial rates fell quickly after about five to ten minutes to values comparable with those in the published literature. It is concluded that anodized and chromate conversion coatings on the aluminum outer surfaces of a sounding rocket experiment package will cause gross distortion of the true water vapor environment.

  9. Data Assimilation of AIRS Water Vapor Profiles: Impact on Precipitation Forecasts for Atmospheric River Cases Affecting the Western of the United States

    Science.gov (United States)

    Blankenship, Clay; Zavodsky, Bradley; Jedlovec, Gary; Wick, Gary; Neiman, Paul

    2013-01-01

    Atmospheric rivers are transient, narrow regions in the atmosphere responsible for the transport of large amounts of water vapor. These phenomena can have a large impact on precipitation. In particular, they can be responsible for intense rain events on the western coast of North America during the winter season. This paper focuses on attempts to improve forecasts of heavy precipitation events in the Western US due to atmospheric rivers. Profiles of water vapor derived from from Atmospheric Infrared Sounder (AIRS) observations are combined with GFS forecasts by a three-dimensional variational data assimilation in the Gridpoint Statistical Interpolation (GSI). Weather Research and Forecasting (WRF) forecasts initialized from the combined field are compared to forecasts initialized from the GFS forecast only for 3 test cases in the winter of 2011. Results will be presented showing the impact of the AIRS profile data on water vapor and temperature fields, and on the resultant precipitation forecasts.

  10. Ozone, water vapor, and temperature anomalies associated with atmospheric blocking events over Eastern Europe in spring - summer 2010

    Science.gov (United States)

    Sitnov, S. A.; Mokhov, I. I.; Lupo, A. R.

    2017-09-01

    Using data from the AIRS satellite instrument (V6, L3), ozone, water vapor (WV), and temperature anomalies associated with the relatively short spring atmospheric blocking event and anomalously prolonged summer block over European Russia (ER) in 2010 are analyzed. Within the domain of the blocking anticyclones, negative total column ozone (TCO) anomalies and positive total column water vapor (TCWV) anomalies reaching the values of -25 and -32 Dobson Units (DU) and 10 and 11 kg m-2 during the spring and summer blocks are observed, respectively. Conversely, within the regions adjacent to the anticyclones to the west and east, positive TCO anomalies (77 and 45 DU) and negative TCWV anomalies (-3 and -4 kg m-2) are found. These TCO and TCWV anomalies are conditioned by the regional atmospheric circulation associated with the strong omega-type blocking. The TCO deficit and TCWV surplus within the atmospheric blocking domain are explained primarily by the poleward advection of subtropical air with low TCO and high TCWV content and tropopause uplift. The TCO and TCWV anomalies are also associated with quasi-stationary Rossby wave trains that accompanied these blocking events. An analysis of the anomaly vertical structure shows that the marked TCO decrease is primarily due to the lower stratospheric ozone decrease, while the strong TCWV increase is mainly the result of an increase of lower tropospheric WV content. The possible role of photochemical ozone destruction in the lower stratosphere due to WV advection within the blocked regions is also discussed. Vertical profiles of the thermal anomalies during both atmospheric blocking events reveal dipole-like structures characterized by positive temperature anomalies in the troposphere and negative anomalies in the lower stratosphere.

  11. Observation of a strong inverse temperature dependence for the opacity of atmospheric water vapor in the mm continuum near 280 GHz

    Science.gov (United States)

    Emmons, Louisa K.; De Zafra, Robert L.

    1990-01-01

    Results are presented of the field measurements of atmospheric opacity at 278 GHz (9.3/cm) conducted at the McMurdo Station (Antarctica) during the austral springs of 1986 and 1987, in conjunction with balloon measurements of water vapor profile and total column density, showing a strong inverse temperature dependence when normalized to precipitable water vapor. The value of measured opacity per mm of precipitable water vapor (PWV) is roughly two times greater at -35 C than at -10 C and three times greater than measurements at +25 C reported by Zammit and Ade (1981). Various theories proposed to explain excess absorption in continuum regions are reviewed.

  12. Retrieval techniques and information content analysis to improve remote sensing of atmospheric water vapor, liquid water and temperature from ground-based microwave radiometer measurements

    Science.gov (United States)

    Sahoo, Swaroop

    Observation of profiles of temperature, humidity and winds with sufficient accuracy and fine vertical and temporal resolution are needed to improve mesoscale weather prediction, track conditions in the lower to mid-troposphere, predict winds for renewable energy, inform the public of severe weather and improve transportation safety. In comparing these thermodynamic variables, the absolute atmospheric temperature varies only by 15%; in contrast, total water vapor may change by up to 50% over several hours. In addition, numerical weather prediction (NWP) models are initialized using water vapor profile information, so improvements in their accuracy and resolution tend to improve the accuracy of NWP. Current water vapor profile observation systems are expensive and have insufficient spatial coverage to observe humidity in the lower to mid-troposphere. To address this important scientific need, the principal objective of this dissertation is to improve the accuracy, vertical resolution and revisit time of tropospheric water vapor profiles retrieved from microwave and millimeter-wave brightness temperature measurements. This dissertation advances the state of knowledge of retrieval of atmospheric water vapor from microwave brightness temperature measurements. It focuses on optimizing two information sources of interest for water vapor profile retrieval, i.e. independent measurements and background data set size. From a theoretical perspective, it determines sets of frequencies in the ranges of 20-23, 85-90 and 165-200 GHz that are optimal for water vapor retrieval from each of ground-based and airborne radiometers. The maximum number of degrees of freedom for the selected frequencies for ground-based radiometers is 5-6, while the optimum vertical resolution is 0.5 to 1.5 km. On the other hand, the maximum number of degrees of freedom for airborne radiometers is 8-9, while the optimum vertical resolution is 0.2 to 0.5 km. From an experimental perspective, brightness

  13. Water vapor adsorption on goethite.

    Science.gov (United States)

    Song, Xiaowei; Boily, Jean-François

    2013-07-02

    Goethite (α-FeOOH) is an important mineral contributing to processes of atmospheric and terrestrial importance. Their interactions with water vapor are particularly relevant in these contexts. In this work, molecular details of water vapor (0.0-19.0 Torr; 0-96% relative humidity at 25 °C) adsorption at surfaces of synthetic goethite nanoparticles reacted with and without HCl and NaCl were resolved using vibrational spectroscopy. This technique probed interactions between surface (hydr)oxo groups and liquid water-like films. Molecular dynamics showed that structures and orientations adopted by these waters are comparable to those adopted at the interface with liquid water. Particle surfaces reacted with HCl accumulated less water than acid-free surfaces due to disruptions in hydrogen bond networks by chemisorbed waters and chloride. Particles reacted with NaCl had lower loadings below ∼10 Torr water vapor but greater loadings above this value than salt-free surfaces. Water adsorption reactions were here affected by competitive hydration of coexisting salt-free surface regions, adsorbed chloride and sodium, as well as precipitated NaCl. Collectively, the findings presented in this study add further insight into the initial mechanisms of thin water film formation at goethite surfaces subjected to variations in water vapor pressure that are relevant to natural systems.

  14. Development of a GPS buoy system for monitoring tsunami, sea waves, ocean bottom crustal deformation and atmospheric water vapor

    Science.gov (United States)

    Kato, Teruyuki; Terada, Yukihiro; Nagai, Toshihiko; Koshimura, Shun'ichi

    2010-05-01

    bottom positions with a few centimeters in accuracy. The system is now operational for more than ten sites along the Japanese coasts. Currently, however, the measurements are not continuous but have been done once to several times a year using a boat. If a GPS and acoustic system is placed on a buoy, ocean bottom position could be monitored in near real-time and continuous manner. This will allow us to monitor more detailed and short term crustal deformations at the sea bottom. Another application plan is for an atmospheric research. Previous researchers have shown that GPS is capable of measuring atmospheric water vapor through estimating tropospheric zenith delay measurements of GPS at the sea surface. Information of water vapor content and its temporal variation over sea surface will much contribute to weather forecast on land which has mostly been conducted only by land observations. Considering that the atmospheric mass moves from west to east in general in and around Japanese islands, information of water vapor together with other atmospheric data from an array of GPS buoy placed in the west of Japanese Islands, will much improve weather forecast. We try to examine if this is also feasible. As a conclusion of a series of GPS buoy experiments, we could assert that GPS buoy system will be a powerful tool to monitor ocean surface and much contribute to provide safe and secure life of people.

  15. Information Content Analysis for the Penn State Upper Atmospheric Water Vapor-Microwave Radiometer Experiment.

    Science.gov (United States)

    1981-01-01

    CONTRACT NO. N00014-79-C-0610 Comissao Nacional de Director Actividades Espaciais U.S. Naval Research Lab Calisca Postal, 515 Washington, DC 20390 San...Jose Dos Campos ATTN: Technical Information Sao Paulo, BRAZIL Division Commander and Director Director Atmospheric Sciences Lab. U.S. Naval Research

  16. Retrieval Assimilation and Modeling of Atmospheric Water Vapor from Ground- and Space-Based GPS Networks: Investigation of the Global and Regional Hydrological Cycles

    Science.gov (United States)

    Dickey, Jean O.

    1999-01-01

    Uncertainty over the response of the atmospheric hydrological cycle (particularly the distribution of water vapor and cloudiness) to anthropogenic forcing is a primary source of doubt in current estimates of global climate sensitivity, which raises severe difficulties in evaluating its likely societal impact. Fortunately, a variety of advanced techniques and sensors are beginning to shed new light on the atmospheric hydrological cycle. One of the most promising makes use of the sensitivity of the Global Positioning System (GPS) to the thermodynamic state, and in particular the water vapor content, of the atmosphere through which the radio signals propagate. Our strategy to derive the maximum benefit for hydrological studies from the rapidly increasing GPS data stream will proceed in three stages: (1) systematically analyze and archive quality-controlled retrievals using state-of-the-art techniques; (2) employ both currently available and innovative assimilation procedures to incorporate these determinations into advanced regional and global atmospheric models and assess their effects; and (3) apply the results to investigate selected scientific issues of relevance to regional and global hydrological studies. An archive of GPS-based estimation of total zenith delay (TZD) data and water vapor where applicable has been established with expanded automated quality control. The accuracy of the GPS estimates is being monitored; the investigation of systematic errors is ongoing using comparisons with water vapor radiometers. Meteorological packages have been implemented. The accuracy and utilization of the TZD estimates has been improved by implementing a troposphere gradient model. GPS-based gradients have been validated as real atmospheric moisture gradients, establishing a link between the estimated gradients and the passage of weather fronts. We have developed a generalized ray tracing inversion scheme that can be used to analyze occultation data acquired from space

  17. Decadal variations in atmospheric water vapor time series estimated using GNSS, ERA-Interim, and synoptic data

    Science.gov (United States)

    Alshawaf, Fadwa; Dick, Galina; Heise, Stefan; Balidakis, Kyriakos; Schmidt, Torsten; Wickert, Jens

    2017-04-01

    Ground-based GNSS (Global Navigation Satellite Systems) have efficiently been used since the 1990s as a meteorological observing system. Recently scientists used GNSS time series of precipitable water vapor (PWV) for climate research although they may not be sufficiently long. In this work, we compare the trend estimated from GNSS time series with that estimated from European Center for Medium-RangeWeather Forecasts Reanalysis (ERA-Interim) data and meteorological measurements.We aim at evaluating climate evolution in Central Europe by monitoring different atmospheric variables such as temperature and PWV. PWV time series were obtained by three methods: 1) estimated from ground-based GNSS observations using the method of precise point positioning, 2) inferred from ERA-Interim data, and 3) determined based on daily surface measurements of temperature and relative humidity. The other variables are available from surface meteorological stations or received from ERA-Interim. The PWV trend component estimated from GNSS data strongly correlates (>70%) with that estimated from the other data sets. The linear trend is estimated by straight line fitting over 30 years of seasonally-adjusted PWV time series obtained using the meteorological measurements. The results show a positive trend in the PWV time series with an increase of 0.2-0.7 mm/decade with a mean standard deviations of 0.016 mm/decade. In this paper, we present the results at three GNSS stations. The temporal increment of the PWV correlates with the temporal increase in the temperature levels.

  18. The vertical distribution of Mars water vapor

    Science.gov (United States)

    Davies, D. W.

    1979-01-01

    Analysis of observations made from the Viking 1 Orbiter indicates that the water vapor over the Viking 1 landing site is uniformly mixed with the atmosphere and not concentrated near the surface. The analysis incorporates the effects of atmospheric scattering and explains why previous earth-based observations showed a strong diurnal variation in water content. It also explains the lack of an early morning fog and removes the necessity of daily exchange of large amounts of water between the surface and the atmosphere. A water vapor volume mixing ratio of 1.5 x 10 to the -4th is inferred for the Viking 1 site in late summer.

  19. Density distributions of OH, Na, water vapor, and water mist in atmospheric-pressure dc helium glow plasmas in contact with NaCl solution

    Science.gov (United States)

    Sasaki, Koichi; Ishigame, Hiroaki; Nishiyama, Shusuke

    2015-07-01

    This paper reports the density distributions of OH, Na, water vapor and water mist in atmospheric-pressure dc helium glow plasmas in contact with NaCl solution. The densities of OH, Na and H2O had different spatial distributions, while the Na density had a similar distribution to mist, suggesting that mist is the source of Na in the gas phase. When the flow rate of helium toward the electrolyte surface was increased, the distributions of all the species densities concentrated in the neighboring region to the electrolyte surface more significantly. The densities of all the species were sensitive to the electric polarity of the power supply. In particular, we never detected Na and mist when the electrolyte worked as the anode of the dc discharge. Contribution to the topical issue "The 14th International Symposium on High Pressure Low Temperature Plasma Chemistry (HAKONE XIV)", edited by Nicolas Gherardi, Ronny Brandenburg and Lars Stollenwark

  20. Technical Note: Harmonized retrieval of column-integrated atmospheric water vapor from the FTIR network - First examples for long-term records and station trends

    OpenAIRE

    Sussmann, R.; T. Borsdorff; M. Rettinger; Camy-Peyret, C.; Demoulin, P.; Duchatelet, P.; Mahieu, E.; Servais, C.

    2009-01-01

    We present a method for harmonized retrieval of integrated water vapor (IWV) from existing, long-term, measurement records at the ground-based mid-infrared solar FTIR spectrometry stations of the Network for the Detection of Atmospheric Composition Change (NDACC). Correlation of IWV from FTIR with radiosondes shows an ideal slope of 1.00(3). This optimum matching is achieved via tuning one FTIR retrieval parameter, i.e., the strength of a Tikhonov regularization constraining...

  1. Mars water vapor, near-surface

    Science.gov (United States)

    Ryan, J. A.; Sharman, R. D.; Lucich, R. D.

    1982-01-01

    In a previous paper we concluded that the temperature sensors aboard the Viking landers (VL-1 and VL-2) were detecting the water vapor frost point. Analysis of one Mars year of data at both lander sites substantiates this conclusion. At VL-1 it is found that the water vapor mixing ratio is constant with height through the bulk of the atmosphere, most of the time. Exceptions are during the onset phases of the two major dust storms when temporary enhancement of near-surface vapor occurs (the same phenomenon is observed at VL-2), and some depletion of near-surface vapor during the decay phase of the first storm, possibly the second storm as well. The former suggests near-surface, northward transport of water vapor with the storms. The latter suggests adsorption of vapor on dust particles followed by surface deposition. At VL-2, severe near-surface depletion of water vapor occurs during northern autumn and winter. The residual vapor is in equilibrium with the surface condensate observed at the site during this period, indicating that the source region for the condensate must be aloft with downward transport by dust fall-out. Since the near-surface water vapor mixing ratio and concentration at VL-1 generally parallels the column abundance over VL-1 obtained by the orbiters, this suggests that VL-1 can be used to give a measure of column abundance for as long as the temperature sensors remain operational.

  2. Accurate Laser Measurements of the Water Vapor Self-Continuum Absorption in Four Near Infrared Atmospheric Windows. a Test of the MT_CKD Model.

    Science.gov (United States)

    Campargue, Alain; Kassi, Samir; Mondelain, Didier; Romanini, Daniele; Lechevallier, Loïc; Vasilchenko, Semyon

    2017-06-01

    The semi empirical MT_CKD model of the absorption continuum of water vapor is widely used in atmospheric radiative transfer codes of the atmosphere of Earth and exoplanets but lacks of experimental validation in the atmospheric windows. Recent laboratory measurements by Fourier transform Spectroscopy have led to self-continuum cross-sections much larger than the MT_CKD values in the near infrared transparency windows. In the present work, we report on accurate water vapor absorption continuum measurements by Cavity Ring Down Spectroscopy (CRDS) and Optical-Feedback-Cavity Enhanced Laser Spectroscopy (OF-CEAS) at selected spectral points of the transparency windows centered around 4.0, 2.1 and 1.25 μm. The temperature dependence of the absorption continuum at 4.38 μm and 3.32 μm is measured in the 23-39 °C range. The self-continuum water vapor absorption is derived either from the baseline variation of spectra recorded for a series of pressure values over a small spectral interval or from baseline monitoring at fixed laser frequency, during pressure ramps. In order to avoid possible bias approaching the water saturation pressure, the maximum pressure value was limited to about 16 Torr, corresponding to a 75% humidity rate. After subtraction of the local water monomer lines contribution, self-continuum cross-sections, C_{S}, were determined with a few % accuracy from the pressure squared dependence of the spectra base line level. Together with our previous CRDS and OF-CEAS measurements in the 2.1 and 1.6 μm windows, the derived water vapor self-continuum provides a unique set of water vapor self-continuum cross-sections for a test of the MT_CKD model in four transparency windows. Although showing some important deviations of the absolute values (up to a factor of 4 at the center of the 2.1 μm window), our accurate measurements validate the overall frequency dependence of the MT_CKD2.8 model.

  3. Importance Profiles for Water Vapor

    Science.gov (United States)

    Mapes, Brian; Chandra, Arunchandra S.; Kuang, Zhiming; Zuidema, Paquita

    2017-10-01

    Motivated by the scientific desire to align observations with quantities of physical interest, we survey how scalar importance functions depend on vertically resolved water vapor. Definitions of importance begin from familiar examples of water mass I m and TOA clear-sky outgoing longwave flux I OLR, in order to establish notation and illustrate graphically how the sensitivity profile or "kernel" depends on whether specific humidity S, relative humidity R, or ln(R) are used as measures of vapor. Then, new results on the sensitivity of convective activity I con to vapor (with implied knock-on effects such as weather prediction skill) are presented. In radiative-convective equilibrium, organized (line-like) convection is much more sensitive to moisture than scattered isotropic convection, but it exists in a drier mean state. The lesson for natural convection may be that organized convection is less susceptible to dryness and can survive and propagate into regions unfavorable for disorganized convection. This counterintuitive interpretive conclusion, with respect to the narrow numerical result behind it, highlights the importance of clarity about what is held constant at what values in sensitivity or susceptibility kernels. Finally, the sensitivities of observable radiance signals I sig for passive remote sensing are considered. While the accuracy of R in the lower free troposphere is crucial for the physical importance scalars, this layer is unfortunately the most difficult to isolate with passive remote sensing: In high emissivity channels, water vapor signals come from too high in the atmosphere (for satellites) or too low (for surface radiometers), while low emissivity channels have poor altitude discrimination and (in the case of satellites) are contaminated by surface emissions. For these reasons, active ranging (LiDAR) is the preferred observing strategy.

  4. Importance Profiles for Water Vapor

    Science.gov (United States)

    Mapes, Brian; Chandra, Arunchandra S.; Kuang, Zhiming; Zuidema, Paquita

    2017-11-01

    Motivated by the scientific desire to align observations with quantities of physical interest, we survey how scalar importance functions depend on vertically resolved water vapor. Definitions of importance begin from familiar examples of water mass I m and TOA clear-sky outgoing longwave flux I OLR, in order to establish notation and illustrate graphically how the sensitivity profile or "kernel" depends on whether specific humidity S, relative humidity R, or ln( R) are used as measures of vapor. Then, new results on the sensitivity of convective activity I con to vapor (with implied knock-on effects such as weather prediction skill) are presented. In radiative-convective equilibrium, organized (line-like) convection is much more sensitive to moisture than scattered isotropic convection, but it exists in a drier mean state. The lesson for natural convection may be that organized convection is less susceptible to dryness and can survive and propagate into regions unfavorable for disorganized convection. This counterintuitive interpretive conclusion, with respect to the narrow numerical result behind it, highlights the importance of clarity about what is held constant at what values in sensitivity or susceptibility kernels. Finally, the sensitivities of observable radiance signals I sig for passive remote sensing are considered. While the accuracy of R in the lower free troposphere is crucial for the physical importance scalars, this layer is unfortunately the most difficult to isolate with passive remote sensing: In high emissivity channels, water vapor signals come from too high in the atmosphere (for satellites) or too low (for surface radiometers), while low emissivity channels have poor altitude discrimination and (in the case of satellites) are contaminated by surface emissions. For these reasons, active ranging (LiDAR) is the preferred observing strategy.

  5. Microspectroscopic imaging of solution plasma: How do its physical properties and chemical species evolve in atmospheric-pressure water vapor bubbles?

    Science.gov (United States)

    Yui, Hiroharu; Banno, Motohiro

    2018-01-01

    In this article, we review the development of scientific instruments for obtaining information on the evolution of physical properties and chemical species of solution plasma (SP). When a pulsed high voltage is applied between electrodes immersed in an aqueous solution, SP is formed in water vapor bubbles transiently generated in the solution under atmospheric pressure. To clarify how SP emerges in water vapor bubbles and is sustained in solutions, an instrument with micrometer spatial resolution and nanosecond temporal resolution is required. To meet these requirements, a microscopic system with a custom-made optical discharge cell was newly developed, where the working distance between the SP and the microscopic objective lens was minimized. A hollow electrode equipped in the discharge cell also enabled us to control the chemical composition in water vapor bubbles. To study the spatial and temporal evolutions of chemical species in micrometer and nano- to microsecond regions, a streak camera with a spectrometer and a CCD detector with a time-gated electronic device were combined with the microscope system. The developed instrument is expected to contribute to providing a new means of developing new schemes for chemical reactions and material syntheses.

  6. Evaluation of an airborne triple-pulsed 2 μm IPDA lidar for simultaneous and independent atmospheric water vapor and carbon dioxide measurements.

    Science.gov (United States)

    Refaat, Tamer F; Singh, Upendra N; Yu, Jirong; Petros, Mulugeta; Ismail, Syed; Kavaya, Michael J; Davis, Kenneth J

    2015-02-20

    Water vapor and carbon dioxide are the most dominant greenhouse gases directly contributing to the Earth's radiation budget and global warming. A performance evaluation of an airborne triple-pulsed integrated path differential absorption (IPDA) lidar system for simultaneous and independent monitoring of atmospheric water vapor and carbon dioxide column amounts is presented. This system leverages a state-of-the-art Ho:Tm:YLF triple-pulse laser transmitter operating at 2.05 μm wavelength. The transmitter provides wavelength tuning and locking capabilities for each pulse. The IPDA lidar system leverages a low risk and technologically mature receiver system based on InGaAs pin detectors. Measurement methodology and wavelength setting are discussed. The IPDA lidar return signals and error budget are analyzed for airborne operation on-board the NASA B-200. Results indicate that the IPDA lidar system is capable of measuring water vapor and carbon dioxide differential optical depth with 0.5% and 0.2% accuracy, respectively, from an altitude of 8 km to the surface and with 10 s averaging. Provided availability of meteorological data, in terms of temperature, pressure, and relative humidity vertical profiles, the differential optical depth conversion into weighted-average column dry-air volume-mixing ratio is also presented.

  7. Insights from a network of long-term measurements of biosphere-atmospheric exchanges of water vapor and carbon dioxide in a water-limited semiarid region

    Science.gov (United States)

    Scott, Russell; Biederman, Joel

    2017-04-01

    Around one-third of Earth's land surface is classified as semiarid, and carbon dioxide exchange in these regions has been shown to be an important regulator of both the trend and interannual variability of the terrestrial carbon sink. Fifteen years ago, when we began making measurements of biosphere-atmospheric exchanges of energy, water vapor, and carbon dioxide using eddy covariance in southern Arizona USA, there was paucity of semiarid observations in flux networks like AmeriFlux and EuroFlux. We started by establishing riparian sites across a woody plant encroachment gradient to quantify the productivity and consumptive plant water use along a iconic and ecologically important desert river. Soon thereafter, we added semiarid grassland, shrubland, and savanna sites that do not have access to groundwater in order to better understand how water limitation and changes in vegetation structure affect ecosystem productivity. Here, we highlight the value of multiyear, multisite flux data for addressing regional to global scale problems associated with groundwater pumping, land cover change, drought, and climate change. For the riparian sites, we find that ecosystem water availability is altered by vegetation structure such that ecosystems with more deeply rooted trees have higher productivity but at a cost of greater groundwater use. For the non-riparian sites, precipitation strongly controls ecosystem water availability and the resultant productivity, but differences in ecosystem structure impact water use efficiency due to the partitioning of evapotranspiration into its component sources. Also, the productivity at sites with more grass, and less woody, plants responds more quickly to precipitation fluctuations including long-term drought conditions. In semiarid regions, variability in water and carbon fluxes is much larger than in more mesic climes. Across our riparian and non-riparian sites, access to more stable groundwater reserves reduces variability in water and

  8. Effect of water vapor on plasma morphology, OH and H2O2 production in He and Ar atmospheric pressure dielectric barrier discharges

    Science.gov (United States)

    Du, Yanjun; Nayak, Gaurav; Oinuma, Gaku; Peng, Zhimin; Bruggeman, Peter J.

    2017-04-01

    Although atmospheric pressure dielectric barrier discharges (DBDs) have a long history, the effects of water vapor on the discharge morphology and kinetics have not been studied intensively. We report a simultaneous investigation of discharge morphology, OH and H2O2 production in Ar and He DBDs operated at different water vapor concentrations and powers. The combined study allows us to assess the impact of the discharge morphology and power on the concentration dependence of the OH and H2O2 production. The morphology of the discharge is investigated by ICCD images and current-voltage waveforms. These diagnostics are complemented by broadband absorption and a colorimetric method to measure the gas temperature and the OH and H2O2 concentrations. The number of filaments in Ar DBD increases with increasing water concentration and power. The surface discharge part of the micro-discharge also reduces with increasing water concentration most likely due to a change in surface conductivity of the dielectric with changing water concentration. The OH density in the case of Ar is approximately double the OH density in He for similar power and water admixture. In contrast to the root square dependence of the OH density on the water concentration in He similar to diffuse RF discharges, the OH density in Ar increases for small water concentrations followed by a saturation and reduces for higher water concentrations. This dependence of OH density on water concentration is found to correlate with changes in discharge morphology. An analytical balance of the production and destruction mechanism of H2O2 is shown to be able to reproduce the ratio of the measured OH and H2O2 density for realistic values of electron densities.

  9. Ground-Based Global Positioning System (GPS) Meteorology Integrated Precipitable Water Vapor (IPW)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Ground-Based Global Positioning System (GPS) Meteorology Integrated Precipitable Water Vapor (IPW) data set measures atmospheric water vapor using ground-based...

  10. Regolith water vapor sources on Mars: A historical bibliography

    Science.gov (United States)

    Clifford, Stephen M.; Huguenin, R. L.

    1988-01-01

    The regolith as a potential source and sink of atmospheric water is examined bibliographically. The controversy surrounding Solis Lacus, a region on Mars first identified by R. Huguenin as a possible regolith source of atmospheric water vapor, is reviewed. The publications listed describe the initial debate over the existence of a regolith source of atmospheric water vapor in Solis Lacus. The debate over Solis Lacus has motivated a rigorous examination of several important data sets, and helped define the limits of their interpretation.

  11. Vapor scavenging by atmospheric aerosol particles

    Energy Technology Data Exchange (ETDEWEB)

    Andrews, E.

    1996-05-01

    Particle growth due to vapor scavenging was studied using both experimental and computational techniques. Vapor scavenging by particles is an important physical process in the atmosphere because it can result in changes to particle properties (e.g., size, shape, composition, and activity) and, thus, influence atmospheric phenomena in which particles play a role, such as cloud formation and long range transport. The influence of organic vapor on the evolution of a particle mass size distribution was investigated using a modified version of MAEROS (a multicomponent aerosol dynamics code). The modeling study attempted to identify the sources of organic aerosol observed by Novakov and Penner (1993) in a field study in Puerto Rico. Experimentally, vapor scavenging and particle growth were investigated using two techniques. The influence of the presence of organic vapor on the particle`s hydroscopicity was investigated using an electrodynamic balance. The charge on a particle was investigated theoretically and experimentally. A prototype apparatus--the refractive index thermal diffusion chamber (RITDC)--was developed to study multiple particles in the same environment at the same time.

  12. Refraction of microwave signals by water vapor

    Science.gov (United States)

    Goldfinger, A. D.

    1980-01-01

    Tropospheric water vapor causes a refractive path length effect which is typically 5-10% of the 'dry' tropospheric effect and as large as several meters at elevation angles below 5 deg. The vertical water vapor profile is quite variable, and measurements of intensive atmospheric parameters such as temperature and humidity limited to the surface do not adequately predict the refractive effect. It is suggested that a water vapor refraction model that is a function of the amount of precipitable water alone can be successful at low elevation angles. From an extensive study of numerical ray tracings through radiosonde balloon data, such a model has been constructed. The model predicts the effect at all latitudes and elevation angles between 2 and 10 deg to an accuracy of better than 4% (11 cm at 3 deg elevation angle).

  13. Kinetics and dynamics of nanosecond streamer discharge in atmospheric-pressure gas bubble suspended in distilled water under saturated vapor pressure conditions

    KAUST Repository

    Sharma, Ashish

    2016-09-08

    We perform computational studies of nanosecond streamer discharges generated in helium bubbles immersed in distilled water under atmospheric pressure conditions. The model takes into account the presence of water vapor in the gas bubble for an accurate description of the discharge kinetics. We find that the dynamic characteristics of the streamer discharge are different at low and high positive trigger voltages with the axial streamer evolution dominant for low voltages and a surface hugging mode favored for high voltages. We also find a substantial difference in initiation, transition and evolution stages of discharge for positive and negative trigger voltages with the volumetric distribution of species in the streamer channel much more uniform for negative trigger voltages on account of the presence of multiple streamers. We observe that the presence of water vapor does not affect the breakdown voltage even for oversaturated conditions but significantly influences the composition of dominant species in the trail of the streamer as well as the flux of the dominant species on the bubble surface. © 2016 IOP Publishing Ltd.

  14. Kinetics and dynamics of nanosecond streamer discharge in atmospheric-pressure gas bubble suspended in distilled water under saturated vapor pressure conditions

    Science.gov (United States)

    Sharma, Ashish; Levko, Dmitry; Raja, Laxminarayan L.; Cha, Min Suk

    2016-10-01

    We perform computational studies of nanosecond streamer discharges generated in helium bubbles immersed in distilled water under atmospheric pressure conditions. The model takes into account the presence of water vapor in the gas bubble for an accurate description of the discharge kinetics. We find that the dynamic characteristics of the streamer discharge are different at low and high positive trigger voltages with the axial streamer evolution dominant for low voltages and a surface hugging mode favored for high voltages. We also find a substantial difference in initiation, transition and evolution stages of discharge for positive and negative trigger voltages with the volumetric distribution of species in the streamer channel much more uniform for negative trigger voltages on account of the presence of multiple streamers. We observe that the presence of water vapor does not affect the breakdown voltage even for oversaturated conditions but significantly influences the composition of dominant species in the trail of the streamer as well as the flux of the dominant species on the bubble surface.

  15. Retrieval of atmospheric-temperature and water-vapor profiles by use of combined satellite and ground-based infrared spectral-radiance measurements.

    Science.gov (United States)

    Ho, Shu-Peng; Smith, William L; Huang, Hung-Lung

    2002-07-10

    A nonlinear sounding retrieval algorithm is used to produce vertical-temperature and water-vapor profiles from coincident observations taken by the airborne High-resolution Interferometer Sounder (HIS) and the ground-based Atmospheric Emitted Radiance Interferometer (AERI) during the SUbsonic Contrails and Clouds Effects Special Study (SUCCESS). Also, clear sky Geostationary Operational Environmental Satellite (GOES) and AERI radiance measurements, achieved on a daily real-time basis at the Department of Energy's Oklahoma CART (Cloud and Radiation Testbed) site, are used to demonstrate the current profiling capability by use of simultaneous geostationary satellite and ground-based remote sensing observations under clear-sky conditions. The discrepancy principle, a method to find the proper smoothing parameters from the minimum value between the normalized spectral residual norm and the a priori upper bound, is used to demonstrate the feasibility and effectiveness of on-line simultaneous tuning of the multiple weighting and smoothing parameters from the combined satellite/airborne and ground-based measurements for the temperature and water-vapor retrieval in this nonlinear-retrieval process. An objective method to determine the degrees of freedom (d.f.) of the observation signal is derived. The d.f. of the radiance signal for the combined GOES and AERI measurements is larger than that for either instrument alone; while the d.f. of the observation signal for the combined GOES and AERI measurements is larger than that for either instrument alone and of the combined GOES and AERI measurements. The use of simultaneous clear-sky AERI and GOES data now provides improved vertical temperature and moisture soundings on an hourly basis for use in the Atmospheric Radiation Measurement program [J. Appl. Meteorol. 37, 875 (1998)].

  16. Technical Note: Harmonized retrieval of column-integrated atmospheric water vapor from the FTIR network – first examples for long-term records and station trends

    Directory of Open Access Journals (Sweden)

    C. Servais

    2009-11-01

    Full Text Available We present a method for harmonized retrieval of integrated water vapor (IWV from existing, long-term, measurement records at the ground-based mid-infrared solar FTIR spectrometry stations of the Network for the Detection of Atmospheric Composition Change (NDACC. Correlation of IWV from FTIR with radiosondes shows an ideal slope of 1.00(3. This optimum matching is achieved via tuning one FTIR retrieval parameter, i.e., the strength of a Tikhonov regularization constraining the derivative (with respect to height of retrieved water profiles given in per cent difference relative to an a priori profile. All other FTIR-sonde correlation parameters (intercept=0.02(12 mm, bias=0.02(5 mm, standard deviation of coincident IWV differences (stdv=0.27 mm, R=0.99 are comparable to or better than results for all other ground-based IWV sounding techniques given in the literature. An FTIR-FTIR side-by-side intercomparison reveals a strong exponential increase in stdv as a function of increasing temporal mismatch starting at Δt≈1 min. This is due to atmospheric water vapor variability. Based on this result we derive an upper limit for the precision of the FTIR IWV retrieval for the smallest Δt(=3.75 min still giving a statistically sufficient sample (32 coincidences, i.e., precision(IWVFTIR As first application examples long-term IWV data sets are retrieved from the FTIR records of the Zugspitze (47.4° N, 11.0° E, 2964 m a.s.l. and Jungfraujoch (46.5° N, 8.0° E, 3580 m a.s.l. NDACC sites. Station-trend analysis comprises a linear fit after subtracting an intra-annual model (3 Fourier components and constructing an uncertainty interval [95% confidence] via bootstrap resampling. For the Zugspitze a significant trend of 0.79 [0.65, 0.92] mm/decade is found for the time interval [1996–2008], whereas for the Jungfraujoch no significant trend is found. This confirms recent findings that strong variations of IWV trends do occur above land on the local to

  17. Ground-based atmospheric water vapor monitoring system with spectroscopy of radiation in 20-30 GHz and 50-60 GHz bands

    Science.gov (United States)

    Nagasaki, Takeo; Tajima, Osamu; Araki, Kentaro; Ishimoto, Hiroshi

    2016-07-01

    We propose a novel ground-based meteorological monitoring system. In the 20{30 GHz band, our system simultaneously measures a broad absorption peak of water vapor and cloud liquid water. Additional observation in the 50{60 GHz band obtains the radiation of oxygen. Spectral results contain vertical profiles of the physical temperature of atmospheric molecules. We designed a simple method for placing the system atop high buildings and mountains and on decks of ships. There is a simple optical system in front of horn antennas for each frequency band. A focused signal from a reflector is separated into two polarized optical paths by a wire grid. Each signal received by the horn antenna is amplified by low-noise amplifiers. Spectra of each signal are measured as a function of frequency using two analyzers. A blackbody calibration source is maintained at 50 K in a cryostat. The calibration signal is led to each receiver via the wire grid. The input path of the signal is selected by rotation of the wire grid by 90°, because the polarization axis of the reflected path and axis of the transparent path are orthogonal. We developed a prototype receiver and demonstrated its performance using monitoring at the zenith.

  18. The impact of data assimilation of ground-based GPS precipitable water vapor to numerical weather prediction model on estimation of ray-traced atmospheric slant delays

    Science.gov (United States)

    Ichikawa, R.; Hobiger, T.; Shoji, Y.; Miyauchi, Y.

    2012-12-01

    The ''KAshima RAytracing Tools (KARAT)'' is capable of calculating total slant delays and ray-bending angles considering real atmospheric phenomena. One advantage of KARAT is that the reduction of atmospheric path delay will become more accurate each time the numerical weather model is improved. On October 27, 2009 the JMA started data assimilation of zenith wet delays obtained by the GPS Earth Observation Network System (GEONET) operated by Geospatial Information Authority of Japan (GSI) for meso-scale NWP model. The improved NWP model data assimilating the GPS PWV data has the potential to correct the atmospheric path delay more precisely. Meteorological Research Institute (MRI) of Japan has evaluated the impact of ground-based GPS precipitable water vapor (GPS PWV) derived from the GEONET on meso-scale NWP model under the localized heavy rainfall event in Tokyo, Japan on 5 August 2008. A terrific thunderstorm occurred across the Kanto area of Japan, and it caused flooding in downtown Tokyo. During the event, the rainfall intensity increased to over 100 mm per hour within thirty minutes. We have assessed the impacts of GPS PWV assimilation into the NWP model on the KARAT correction by comparisons of the precise point positioning (PPP) solutions. In the nationwide scale of Japan, the short time repeatability of the PPP results for both horizontal and height positions applying KARAT correction through the MRI NWP model with GPS PWV assimilation are about several percent better than that through the conventional MRI NPW model w/o GPS PWV assimilation. In addition we are now investigating the impact of GPS PWV data assimilation in more detail. We will present the updated results of the comparison study.

  19. ARIS-Campaign: intercomparison of three ground based 22 GHz radiometers for middle atmospheric water vapor at the Zugspitze in winter 2009

    Science.gov (United States)

    Straub, C.; Murk, A.; Kämpfer, N.; Golchert, S. H. W.; Hochschild, G.; Hallgren, K.; Hartogh, P.

    2011-09-01

    This paper presents the Alpine Radiometer Intercomparison at the Schneefernerhaus (ARIS), which took place in winter 2009 at the high altitude station at the Zugspitze, Germany (47.42° N, 10.98° E, 2650 m). This campaign was the first direct intercomparison between three new ground based 22 GHz water vapor radiometers for middle atmospheric profiling with the following instruments participating: MIRA 5 (Karlsruhe Institute of Technology), cWASPAM3 (Max Planck Institute for Solar System Research, Katlenburg-Lindau) and MIAWARA-C (Institute of Applied Physics, University of Bern). Even though the three radiometers all measure middle atmospheric water vapor using the same rotational transition line and similar fundamental set-ups, there are major differences between the front ends, the back ends, the calibration concepts and the profile retrieval. The spectrum comparison shows that all three radiometers measure spectra without severe baseline artifacts and that the measurements are in good general agreement. The measurement noise shows good agreement to the values theoretically expected from the radiometer noise formula. At the same time the comparison of the noise levels shows that there is room for instrumental and calibration improvement, emphasizing the importance of low elevation angles for the observation, a low receiver noise temperature and an efficient calibration scheme. The comparisons of the retrieved profiles show that the agreement between the profiles of MIAWARA-C and cWASPAM3 with the ones of MLS is better than 0.3 ppmv (6%) at all altitudes. MIRA 5 has a dry bias of approximately 0.5 ppm (8%) below 0.1 hPa with respect to all other instruments. The profiles of cWASPAM3 and MIAWARA-C could not be directly compared because the vertical region of overlap was too small. The comparison of the time series at different altitude levels show a similar evolution of the H2O volume mixing ratio (VMR) for the ground based instruments as well as the space borne

  20. ARIS-Campaign: intercomparison of three ground based 22 GHz radiometers for middle atmospheric water vapor at the Zugspitze in winter 2009

    Directory of Open Access Journals (Sweden)

    C. Straub

    2011-09-01

    Full Text Available This paper presents the Alpine Radiometer Intercomparison at the Schneefernerhaus (ARIS, which took place in winter 2009 at the high altitude station at the Zugspitze, Germany (47.42° N, 10.98° E, 2650 m. This campaign was the first direct intercomparison between three new ground based 22 GHz water vapor radiometers for middle atmospheric profiling with the following instruments participating: MIRA 5 (Karlsruhe Institute of Technology, cWASPAM3 (Max Planck Institute for Solar System Research, Katlenburg-Lindau and MIAWARA-C (Institute of Applied Physics, University of Bern. Even though the three radiometers all measure middle atmospheric water vapor using the same rotational transition line and similar fundamental set-ups, there are major differences between the front ends, the back ends, the calibration concepts and the profile retrieval. The spectrum comparison shows that all three radiometers measure spectra without severe baseline artifacts and that the measurements are in good general agreement. The measurement noise shows good agreement to the values theoretically expected from the radiometer noise formula. At the same time the comparison of the noise levels shows that there is room for instrumental and calibration improvement, emphasizing the importance of low elevation angles for the observation, a low receiver noise temperature and an efficient calibration scheme.

    The comparisons of the retrieved profiles show that the agreement between the profiles of MIAWARA-C and cWASPAM3 with the ones of MLS is better than 0.3 ppmv (6% at all altitudes. MIRA 5 has a dry bias of approximately 0.5 ppm (8% below 0.1 hPa with respect to all other instruments. The profiles of cWASPAM3 and MIAWARA-C could not be directly compared because the vertical region of overlap was too small. The comparison of the time series at different altitude levels show a similar evolution of the H2O volume mixing ratio (VMR for the ground based

  1. Insights from a network of long-term measurements of biosphere-atmospheric exchanges of water vapor and carbon dioxide in southern Arizona

    Science.gov (United States)

    Scott, R. L.; Barron-Gafford, G.; Biederman, J. A.

    2016-12-01

    Around one-third of Earth's land surface is classified as semiarid, and carbon dioxide exchange in these regions has been shown to be an important regulator of both the trend and interannual variability of the terrestrial carbon sink. Fifteen years ago, when we began making measurements of biosphere-atmospheric exchanges of energy, water vapor, and carbon dioxide using eddy covariance in southern Arizona USA, there was paucity of semiarid observations in flux networks like Ameriflux. We started by establishing riparian sites across a woody plant encroachment gradient to quantify the productivity and consumptive plant water use along a iconic and ecologically important desert river. Soon thereafter, we added semiarid grassland, shrubland, and savanna sites that do not have access to groundwater in order to better understand how water limitation and changes in vegetation structure affect ecosystem productivity. Here, we highlight the value of multiyear, multisite flux data for addressing regional to global scale problems associated with groundwater pumping, land cover change, drought, and climate change. For the riparian sites, we find that ecosystem water availability is altered by vegetation structure such that ecosystems with more deeply rooted trees have higher productivity but at a cost of greater groundwater use. For the non-riparian sites, precipitation strongly controls ecosystem water availability and the resultant productivity, but differences in ecosystem structure impact water use efficiency due to the partitioning of evapotranspiration into its component sources. Also, the productivity at sites with more grass, and less woody, plants responds more quickly to precipitation fluctuations including long-term drought conditions. In semiarid regions, variability in water and carbon fluxes is much larger than in more mesic climes. Across our riparian and non-riparian sites, access to more stable groundwater reserves reduces variability in water and carbon

  2. Technical Note: Harmonized retrieval of column-integrated atmospheric water vapor from the FTIR network - first examples for long-term records and station trends

    Science.gov (United States)

    Sussmann, R.; Borsdorff, T.; Rettinger, M.; Camy-Peyret, C.; Demoulin, P.; Duchatelet, P.; Mahieu, E.; Servais, C.

    2009-11-01

    We present a method for harmonized retrieval of integrated water vapor (IWV) from existing, long-term, measurement records at the ground-based mid-infrared solar FTIR spectrometry stations of the Network for the Detection of Atmospheric Composition Change (NDACC). Correlation of IWV from FTIR with radiosondes shows an ideal slope of 1.00(3). This optimum matching is achieved via tuning one FTIR retrieval parameter, i.e., the strength of a Tikhonov regularization constraining the derivative (with respect to height) of retrieved water profiles given in per cent difference relative to an a priori profile. All other FTIR-sonde correlation parameters (intercept=0.02(12) mm, bias=0.02(5) mm, standard deviation of coincident IWV differences (stdv)=0.27 mm, R=0.99) are comparable to or better than results for all other ground-based IWV sounding techniques given in the literature. An FTIR-FTIR side-by-side intercomparison reveals a strong exponential increase in stdv as a function of increasing temporal mismatch starting at Δt≍1 min. This is due to atmospheric water vapor variability. Based on this result we derive an upper limit for the precision of the FTIR IWV retrieval for the smallest Δt(=3.75 min) still giving a statistically sufficient sample (32 coincidences), i.e., precision(IWVFTIR)bias of the IWV retrievals from the two different FTIR instruments is nearly negligible (0.02(1) mm). The optimized FTIR IWV retrieval is set up in the standard NDACC algorithm SFIT 2 without changes to the code. A concept for harmonized transfer of the retrieval between different stations deals with all relevant control parameters; it includes correction for differing spectral point spacings (via regularization strength), and final quality selection of the retrievals (excluding the highest residuals (measurement minus model), 5% of the total). As first application examples long-term IWV data sets are retrieved from the FTIR records of the Zugspitze (47.4° N, 11.0° E, 2964 m a

  3. Characterization of a Compact Water Vapor Radiometer

    Science.gov (United States)

    Gill, Ajay; Selina, Rob

    2018-01-01

    We report on laboratory test results of the Compact Water Vapor Radiometer (CWVR) prototype for the Karl G. Jansky Very Large Array (VLA), a five-channel design centered around the 22 GHz water vapor line. Fluctuations in perceptible water vapor cause fluctuations in atmospheric brightness emission, which are assumed to be proportional to phase fluctuations of the astronomical signal seen by an antenna. The design is intended to support empirical radiometric phase corrections for each baseline in the array.The dynamic range, channel isolation, and gain stability of the device were characterized. The device has a useful dynamic range of order 18 dB after calibration, and the CWVR channel isolation requirement of 102.6 sec. With temperature corrections, the single channel and channel difference gain stability per channel is < 2 x 10-4 over τ = 2.5 - 103 sec, which meets the < 2 x 10-4 requirement. The observable gain stability is < 2.5 x 10-4 over τ = 2.5 - 103 sec, which meets the < 2.5 x 10-4 requirement.Overall, the test results indicate that the CWVR meets required specifications for dynamic range, channel isolation, and gain stability in order to proceed with testing on a pair of VLA antennas.

  4. The Zugspitze radiative closure experiment for quantifying water vapor absorption over the terrestrial and solar infrared – Part 3: Quantification of the mid- and near-infrared water vapor continuum in the 2500 to 7800 cm−1 spectral range under atmospheric conditions

    Directory of Open Access Journals (Sweden)

    A. Reichert

    2016-09-01

    Full Text Available We present a first quantification of the near-infrared (NIR water vapor continuum absorption from an atmospheric radiative closure experiment carried out at the Zugspitze (47.42° N, 10.98° E; 2964 m a.s.l.. Continuum quantification is achieved via radiative closure using radiometrically calibrated solar Fourier transform infrared (FTIR absorption spectra covering the 2500 to 7800 cm−1 spectral range. The dry atmospheric conditions at the Zugspitze site (IWV 1.4 to 3.3 mm enable continuum quantification even within water vapor absorption bands, while upper limits for continuum absorption can be provided in the centers of window regions. Throughout 75 % of the 2500 to 7800 cm−1 spectral range, the Zugspitze results agree within our estimated uncertainty with the widely used MT_CKD 2.5.2 model (Mlawer et al., 2012. In the wings of water vapor absorption bands, our measurements indicate about 2–5 times stronger continuum absorption than MT_CKD, namely in the 2800 to 3000 cm−1 and 4100 to 4200 cm−1 spectral ranges. The measurements are consistent with the laboratory measurements of Mondelain et al. (2015, which rely on cavity ring-down spectroscopy (CDRS, and the calorimetric–interferometric measurements of Bicknell et al. (2006. Compared to the recent FTIR laboratory studies of Ptashnik et al. (2012, 2013, our measurements are consistent within the estimated errors throughout most of the spectral range. However, in the wings of water vapor absorption bands our measurements indicate typically 2–3 times weaker continuum absorption under atmospheric conditions, namely in the 3200 to 3400, 4050 to 4200, and 6950 to 7050 cm−1 spectral regions.

  5. CRISM Observations of Water Vapor and Carbon Monoxide

    Science.gov (United States)

    Smith, Michael D.; Wolff, Michael J.; Clancy, R. Todd

    2008-01-01

    Near-infrared spectra returned by the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM, [1]) on-board the Mars Reconnaissance Orbiter (MRO) contain the clear spectral signature of several atmospheric gases including carbon dioxide (CO2), water vapor (H2O), and carbon monoxide (CO). Here we describe the seasonal and spatial mapping of water vapor and carbon dioxide for one full Martian year using CRISM spectra.

  6. Water Vapor Permeation in Plastics

    Energy Technology Data Exchange (ETDEWEB)

    Keller, Paul E. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Kouzes, Richard T. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2017-01-01

    Polyvinyl toluene (PVT) and polystyrene (PS) (referred to as “plastic scintillator”) are used for gamma ray detectors. A significant decrease in radiation detection performance has been observed in some PVT-based gamma-ray detectors in systems in outdoor environments as they age. Recent studies have revealed that plastic scintillator can undergo an environmentally related material degradation that adversely affects gamma ray detection performance under certain conditions and histories. A significant decrease in sensitivity has been seen in some gamma-ray detectors in some systems as they age. The degradation of sensitivity of plastic scintillator over time is due to a variety of factors, and the term “aging” is used to encompass all factors. Some plastic scintillator samples show no aging effects (no significant change in sensitivity over more than 10 years), while others show severe aging (significant change in sensitivity in less than 5 years). Aging effects arise from weather (variations in heat and humidity), chemical exposure, mechanical stress, light exposure, and loss of volatile components. The damage produced by these various causes can be cumulative, causing observable damage to increase over time. Damage may be reversible up to some point, but becomes permanent under some conditions. The objective of this report is to document the phenomenon of permeability of plastic scintillator to water vapor and to derive the relationship between time, temperature, humidity and degree of water penetration in plastic. Several conclusions are documented about the properties of water permeability of plastic scintillator.

  7. A steady-state analysis of the temperature responses of water vapor and aerosol lifetimes

    NARCIS (Netherlands)

    Roelofs, G.J.H.|info:eu-repo/dai/nl/100925375

    2013-01-01

    The dominant removal mechanism of soluble aerosol is wet deposition. The atmospheric lifetime of aerosol, relevant for aerosol radiative forcing, is therefore coupled to the atmospheric cycling time of water vapor. This study investigates the coupling between water vapor and aerosol lifetimes in a

  8. MODIS/Aqua Temperature and Water Vapor Profiles 5-Min L2 Swath 5km - NRT

    Data.gov (United States)

    National Aeronautics and Space Administration — The level-2 MODIS Temperature and Water Vapor Profile Product MYD07_L2 consists of 30 gridded parameters related to atmospheric stability, atmospheric temperature...

  9. Lidar Atmopheric Sensing Experiment (LASE) Data Obtained During the ARM-FIRE Water Vapor Experiment (AFWEX)

    Data.gov (United States)

    National Aeronautics and Space Administration — LASE_AFWEX data are Lidar Atmospheric Sensing Experiment water vapor and aerosol data measurements taken during ARM-FIRE (Atmospheric Radiation Measurement - First...

  10. Logarithmic radiative effect of water vapor and spectral kernels

    Science.gov (United States)

    Bani Shahabadi, Maziar; Huang, Yi

    2014-05-01

    Radiative kernels have become a useful tool in climate analysis. A set of spectral kernels is calculated using a moderate resolution atmospheric transmission code MODTRAN and implemented in diagnosing spectrally decomposed global outgoing longwave radiation (OLR) changes. It is found that the effect of water vapor on the OLR is in proportion to the logarithm of its concentration. Spectral analysis discloses that this logarithmic dependency mainly results from water vapor absorption bands (0-560 cm-1 and 1250-1850 cm-1), while in the window region (800-1250 cm-1), the effect scales more linearly to its concentration. The logarithmic and linear effects in the respective spectral regions are validated by the calculations of a benchmark line-by-line radiative transfer model LBLRTM. The analysis based on LBLRTM-calculated second-order kernels shows that the nonlinear (logarithmic) effect results from the damping of the OLR sensitivity to layer-wise water vapor perturbation by both intra- and inter-layer effects. Given that different scaling approaches suit different spectral regions, it is advisable to apply the kernels in a hybrid manner in diagnosing the water vapor radiative effect. Applying logarithmic scaling in the water vapor absorption bands where absorption is strong and linear scaling in the window region where absorption is weak can generally constrain the error to within 10% of the overall OLR change for up to eightfold water vapor perturbations.

  11. Six-channel multi-wavelength polarization Raman lidar for aerosol and water vapor profiling.

    Science.gov (United States)

    Wang, Zhaofei; Mao, Jiandong; Li, Juan; Zhao, Hu; Zhou, Chunyan; Sheng, Hongjiang

    2017-07-10

    Aerosols and water vapor are important atmospheric components, and have significant effects on both atmospheric energy conversion and climate formation. They play the important roles in balancing the radiation budget between the atmosphere and Earth, while water vapor also directly affects rainfall and other weather processes. To further research atmospheric aerosol optical properties and water vapor content, an all-time six-channel multi-wavelength polarization Raman lidar has been developed at Beifang University of Nationalities. In addition to 1064, 532, and 355 nm Mie scattering channels, the lidar has a polarization channel for 532 nm return signals, a 660 nm water vapor channel, and a 607 nm nitrogen detection channel. Experiments verified the lidar's feasibility and return signals from six channels were detected. Using inversion algorithms, extinction coefficient profiles at 1064, 532 and 355 nm, Ångström exponent profiles, depolarization ratio profiles, and water vapor mixing ratio profiles were all obtained. The polarization characteristics and water vapor content of cirrus clouds, the polarization characteristics of dusty weather, and the water vapor profiles over different days were also analyzed. Results show that the lidar has the full-time detection capability for atmospheric aerosol optical properties and water vapor profiles, and real-time measurements of aerosols and water vapor over the Yinchuan area were realized, providing important information for studying the environmental quality and climate change in this area.

  12. An interim reference model for the variability of the middle atmosphere H2O vapor distribution

    Science.gov (United States)

    Remsberg, E. E.; Russell, J. M., III; Wu, C. Y.

    1989-01-01

    Water vapor is an important minor constituent in the studies of the middle atmosphere for a variety of reasons, including its role as a source for active HO(y) chemicals and its use in analysis of transport processes. A number of in situ and remote techniques were employed in the determination of water vapor distributions. Two of the more complete data sets were used to develop an interim reference profile. First, there are the seven months of Nimbus 7 limb infrared monitor of the stratosphere (LIMS) data obtained during Nov. 1978 to May 1979 over the range 64S to 84N latitude and from about 100 to 1 mb in the mid-mesosphere at several fixed Northern Hemisphere mid-latitude sites. These two data sets were combined to give a mid-lattitude, interim reference water vapor profile for the entire vertical range of the middle atmosphere and with accuracies of better than 25 percent. The daily variability of stratospheric water vapor profiles about the monthly mean was also established from these data sets for selected months. Information is also provided on the longitudinal variability of LIMS water vapor profiles about the daily, weekly, and monthly zonal means. Generally, the interim reference water vapor profile and its variability are consistent with prevailing ideas about chemistry and transport.

  13. Water Vapor Corrosion in EBC Constituent Materials

    Science.gov (United States)

    Kowalski, Benjamin; Fox, Dennis; Jacobson, Nathan S.

    2017-01-01

    Environmental Barrier Coating (EBC) materials are sought after to protect ceramic matrix composites (CMC) in high temperature turbine engines. CMCs are particularly susceptible to degradation from oxidation, Ca-Al-Mg-Silicate (CMAS), and water vapor during high temperature operation which necessitates the use of EBCs. However, the work presented here focuses on water vapor induced recession in EBC constituent materials. For example, in the presence of water vapor, silica will react to form Si(OH)4 (g) which will eventually corrode the material away. To investigate the recession rate in EBC constituent materials under high temperature water vapor conditions, thermal gravimetric analysis (TGA) is employed. The degradation process can then be modeled through a simple boundary layer expression. Ultimately, comparisons are made between various single- and poly-crystalline materials (e.g. TiO2, SiO2) against those found in literature.

  14. GOES WATER VAPOR TRANSPORT V1

    Data.gov (United States)

    National Aeronautics and Space Administration — The GOES Water Vapor Transport CD contains nineteen months of geostationary satellite-derived products from the GOES-8 satellite spanning the 1987-1988 El Nino...

  15. Arctic Water Vapor Characteristics from Rawinsondes

    Data.gov (United States)

    National Aeronautics and Space Administration — A gridded climatological monthly-mean data base of Arctic water vapor characteristics has been assembled by combining fixed station data with data from soundings...

  16. Development of an Airborne Triple-Pulse 2-Micron Integrated Path Differential Absorption Lidar (IPDA) for Simultaneous Airborne Column Measurements of Carbon Dioxide and Water Vapor in the Atmosphere

    Science.gov (United States)

    Singh, Upendra N.; Petros, Mulugeta; Refaat, Tamer F.; Yu, Jirong; Antill, Charles W.; Remus, Ruben

    2016-01-01

    This presentation will provide status and details of an airborne 2-micron triple-pulse integrated path differential absorption (IPDA) lidar being developed at NASA Langley Research Center with support from NASA ESTO Instrument Incubator Program. The development of this active optical remote sensing IPDA instrument is targeted for measuring both atmospheric carbon dioxide and water vapor in the atmosphere from an airborne platform. This presentation will focus on the advancement of the 2-micron triple-pulse IPDA lidar development. Updates on the state-of-the-art triple-pulse laser transmitter will be presented including the status of seed laser locking, wavelength control, receiver and detector upgrades, laser packaging and lidar integration. Future plan for IPDA lidar system for ground integration, testing and flight validation will also be presented.

  17. Optical monitor for water vapor concentration

    Science.gov (United States)

    Kebabian, Paul

    1998-01-01

    A system for measuring and monitoring water vapor concentration in a sample uses as a light source an argon discharge lamp, which inherently emits light with a spectral line that is close to a water vapor absorption line. In a preferred embodiment, the argon line is split by a magnetic field parallel to the direction of light propagation from the lamp into sets of components of downshifted and upshifted frequencies of approximately 1575 Gauss. The downshifted components are centered on a water vapor absorption line and are thus readily absorbed by water vapor in the sample; the upshifted components are moved away from that absorption line and are minimally absorbed. A polarization modulator alternately selects the upshifted components or downshifted components and passes the selected components to the sample. After transmission through the sample, the transmitted intensity of a component of the argon line varies as a result of absorption by the water vapor. The system then determines the concentration of water vapor in the sample based on differences in the transmitted intensity between the two sets of components. In alternative embodiments alternate selection of sets of components is achieved by selectively reversing the polarity of the magnetic field or by selectively supplying the magnetic field to the emitting plasma.

  18. Diurnal variations in water vapor over Central and South America

    Science.gov (United States)

    Meza, Amalia; Mendoza, Luciano; Bianchi, Clara

    2016-07-01

    Diurnal variations in atmospheric integrated water vapor (IWV) are studied employing IWV estimates, with a 30 minutes sampling rate, derived from Global Navigation Satellite Systems (GNSS) observations during the period 2007-2013. The analysis was performed in 73 GNSS tracking sites (GPS + GLONASS) which have more than 5 years of data. The selected area involves different climate types, from polar to tropical, with different diurnal variations of the integrated total humidity content. There are many processes that could induce diurnal variations in atmospheric water vapor (Dai et al, 1999 a,b), the most relevant causes are: surface evapotranspiration, atmospheric large-scale vertical motion, atmospheric low-level moisture convergence and precipitation and vertical mixing (which affects the vertical distribution of water vapor but does not affect the IWV). The numerical tools, Singular Value Decomposition and classical Multidimensional Scaling methods, are used to study these variations, considering the measurements made at each stations, as sample in the analysis. The aim of this investigation is to identify the IWV variability with respect to the local time associated to the different climate regions. In order to improve our analysis, all available weather information, such as radiosondes measurements (which are few), measurements of pressure and temperature and Numerical Weather Models reanalysis data, are used. Reference: Dai, A., K. E. Trenberth, and T. R. Karl, 1999 a: Effects of clouds, soil moisture, precipitation and water vapor on diurnal temperature range. J. Climate, 12, 2451-2473. Dai, A., F. Giorgi, and K. E. Trenberth, 1999 b: Observed and model simulated precipitation diurnal cycle over the contiguous United States.J. Geophys. Res., 104, 6377-6402. KEYWORDS: water vapor, diurnal cycle, GNSS

  19. Development of an OF-CEAS laser spectrometer for water vapor isotope measurements at low water concentrations

    NARCIS (Netherlands)

    Landsberg, Janek

    2014-01-01

    The determination of the isotopic composition of water vapor is an important tool in atmospheric research. The isotopic composition of water in Antarctic or Arctic glacial ice can be used as a paleo-thermometer in the reconstruction of climate changes in the past. The isotope ratios of water vapor

  20. Assessment of water vapor content from MIVIS TIR data

    Directory of Open Access Journals (Sweden)

    V. Tramutoli

    2006-06-01

    Full Text Available The main objective of land remotely sensed images is to derive biological, chemical and physical parameters by inverting sample sets of spectral data. For the above aim hyperspectral scanners on airborne platform are a powerful remote sensing instrument for both research and environmental applications because of their spectral resolution and the high operability of the platform. Fine spectral information by MIVIS (airborne hyperspectral scanner operating in 102 channels ranging from VIS to TIR allows researchers to characterize atmospheric parameters and their effects on measured data which produce undesirable features on surface spectral signatures. These effects can be estimated (and remotely sensed radiances corrected if atmospheric spectral transmittance is known at each image pixel. Usually ground-based punctual observations (atmospheric sounding balloons, sun photometers, etc. are used to estimate the main physical parameters (like water vapor and temperature profiles which permit us to estimate atmospheric spectral transmittance by using suitable radiative transfer model and a specific (often too strong assumption which enable atmospheric properties measured only in very few points to be extended to the whole image. Several atmospheric gases produce observable absorption features, but only water vapor strongly varies in time and space. In this work the authors customize a self-sufficient «split-window technique» to derive (at each image pixel atmospheric total columnar water vapor content (TWVC using only MIVIS data collected by the fourth MIVIS spectrometer (Thermal Infrared band. MIVIS radiances have been simulated by means of MODTRAN4 radiative transfer code and the coefficients of linear regression to estimate TWVC from «split-windows» MIVIS radiances, based on 450 atmospheric water vapor profiles obtained by radiosonde data provided by NOAANESDIS. The method has been applied to produce maps describing the spatial variability of

  1. Vapor phase growth of functional pentacene films at atmospheric pressure

    NARCIS (Netherlands)

    Rolin, C.; Vasseur, K.; Niesen, B.; Willegems, M.; Müller, R.; Steudel, S.; Genoe, J.; Heremans, P.

    2012-01-01

    Compared to traditional vacuum evaporation techniques for small organic molecules, organic vapor phase deposition (OVPD) possesses a extra processing parameter: the pressure of process gas Pch. Here, the influence of large Pch variations (from 0.1 mbar to atmospheric pressure) on pentacene thin film

  2. Atmospheric sugar alcohols: evaporation rates and saturation vapor pressures

    DEFF Research Database (Denmark)

    Bilde, Merete; Zardini, Alessandro Alessio; Hong, Juan

    volatile organic molecules. Saturation vapor pressure and the associated temperature dependence (dH) are key parameters for improving predictive atmospheric models. In this work we combine experiments and thermodynamic modeling to investigate these parameters for a series of polyols, so-called sugar...... are allowed to evaporate in a laminar flow reactor, and changes in particle size as function of evaporation time are determined using a scanning mobility particle sizer system. In this work saturation vapor pressures of sugar alcohols at several temperatures have been inferred from such measurements using...

  3. Dynamic water vapor and temperature calibration system.

    Science.gov (United States)

    Montague, F W; Primiano, F P; Saidel, G M

    1984-06-01

    The objective evaluation of thermal and humidification processes in the pulmonary system requires accurate dynamic measurements of temperature and water vapor concentration of a flowing gas mixture. The adequacy of instruments used for such measurements can only be determined by dynamic calibration techniques. We have developed a method of producing step changes in temperature and water vapor content of a gas mixture undergoing controlled steady flow. The system consists of two reservoirs and a slide valve that switches a test section between them. The inlet (usually a probe or catheter tip) of the device to be calibrated is positioned in the test section. The flow rate through the test section is minimally changed during the transition between gas from one reservoir to that of the other. The system has been used to analyze the response of a thermistor and a respiratory mass spectrometer to changes in gas temperature and water vapor.

  4. Evaluating the Impact of Ambient Benzene Vapor Concentrations on Product Water of Condensation Water from Air Technology

    Science.gov (United States)

    2016-03-07

    benzene vapor concentrations representing average outdoor polluted (50 µg/m3) and indoor industrial (640 µg/m3) settings as well as two temperatures...Henry Law calculations estimate. Benzene vapor concentrations representing a polluted outdoor environment resulted in benzene product water...Agency for Toxic Substances and Diseases Registry ATM Atmosphere C Celsius CWFA Condensation Water From Air ECBC Edgewood Chemical

  5. Measurement of atmospheric carbon dioxide and water vapor in built-up urban areas in the Gandhinagar-Ahmedabad region in India using a portable tunable diode laser spectroscopy system.

    Science.gov (United States)

    Roy, Anirban; Sharma, Neetesh Kumar; Chakraborty, Arup Lal; Upadhyay, Abhishek

    2017-11-01

    This paper reports open-path in situ measurements of atmospheric carbon dioxide at Gandhinagar (23.2156°N, 72.6369°E) and Ahmedabad (23.0225°N, 72.5714°E) in the heavily industrialized state of Gujarat in western India. Calibration-free second harmonic wavelength modulation spectroscopy (2f WMS) is used to carry out accurate and fully automated measurements. The mean values of the mole fraction of carbon dioxide at four locations were 438 ppm, 495 ppm, 550 ppm, and 740 ppm, respectively. These values are much higher than the current global average of 406.67 ppm. A 1 mW, 2004-nm vertical cavity surface-emitting laser is used to selectively interrogate the R16 transition of carbon dioxide at 2003.5 nm (4991.2585 cm-1). The 2f WMS signal corresponding to the gas absorption line shape is simulated using spectroscopic parameters available in the HITRAN database and relevant laser parameters that are extracted in situ from non-absorbing spectral wings of the harmonic signals. The mole fraction of carbon dioxide is extracted in real-time by a MATLAB program from least-squares fit of the simulated 2f WMS signal to the corresponding experimentally obtained signal. A 10-mW, 1392.54-nm distributed feedback laser is used at two of the locations to carry out water vapor measurements using direct absorption spectroscopy. This is the first instance of a portable tunable diode laser spectroscopy system being deployed in an urban location in India to measure atmospheric carbon dioxide and water vapor under varying traffic conditions. The measurements clearly demonstrate the need to adopt tunable diode laser spectroscopy for precise long-term monitoring of greenhouse gases in the Indian subcontinent.

  6. Characterization of Upper Troposphere Water Vapor Measurements during AFWEX using LASE

    Science.gov (United States)

    Ferrare, R. A.; Browell, E. V.; Ismail, S.; Kooi, S.; Brasseur, L. H.; Brackett, V. G.; Clayton, M.; Barrick, J.; Linne, H.; Lammert, A.

    2002-01-01

    Water vapor profiles from NASA's Lidar Atmospheric Sensing Experiment (LASE) system acquired during the ARM/FIRE Water Vapor Experiment (AFWEX) are used to characterize upper troposphere water vapor (UTWV) measured by ground-based Raman lidars, radiosondes, and in situ aircraft sensors. Initial comparisons showed the average Vaisala radiosonde measurements to be 5-15% drier than the average LASE, Raman lidar, and DC-8 in situ diode laser hygrometer measurements. We show that corrections to the Raman lidar and Vaisala measurements significantly reduce these differences. Precipitable water vapor (PWV) derived from the LASE water vapor profiles agrees within 3% on average with PWV derived from the ARM ground-based microwave radiometer (MWR). The agreement among the LASE, Raman lidar, and MWR measurements demonstrates how the LASE measurements can be used to characterize both profile and column water vapor measurements and that ARM Raman lidar, when calibrated using the MWR PWV, can provide accurate UTWV measurements.

  7. Fuel for cyclones: How the water vapor budget of a hurricane depends on its motion

    CERN Document Server

    Makarieva, Anastassia M; Nefiodov, Andrei V; Chikunov, Alexander V; Sheil, Douglas; Nobre, Antonio D; Li, Bai-Lian

    2016-01-01

    Tropical cyclones are fueled by water vapor. Here we estimate the oceanic evaporation within an Atlantic hurricane to be less than one sixth of the total moisture flux precipitating over the same area. So how does the hurricane get the remaining water vapor? Our analysis of TRMM rainfall, MERRA atmospheric moisture and hurricane translation velocities suggests that access to water vapor relies on the hurricane's motion -- as it moves through the atmosphere, the hurricane consumes the water vapor it encounters. This depletion of atmospheric moisture by the hurricane leaves a "dry footprint" of suppressed rainfall in its wake. The thermodynamic efficiency of hurricanes -- defined as kinetic energy production divided by total latent heat release associated with the atmospheric moisture supply -- remains several times lower than Carnot efficiency even in the most intense hurricanes. Thus, maximum observed hurricane power cannot be explained by the thermodynamic Carnot limit.

  8. Water vapor analysis with use of sunphotometry and radiosoundings

    Science.gov (United States)

    Pakszys, Paulina; Zielinski, Tymon; Petelski, Tomek; Makuch, Przemyslaw; Strzalkowska, Agata; Markuszewski, Piotr; Kowalczyk, Jakub

    2014-05-01

    Information about vertically integrated content of water vapor in the atmosphere and type, composition and concentration of aerosols is relevant in many types of atmospheric studies. Such information is required to understand mechanisms of global climate and its further modeling (Smirnov et al., 2000). This work is devoted to the description of a basic technique of analysis and comparing the derivation of Columnar Water Vapor (CWV) from different instruments, such as a radiosonde and a sunphotometer. The measurements were carried out using Microtops II Ozone Monitor & Sunphotometer during the cruises onboard the R/V Oceania (13 cruises) and from one cruise onboard of the SY TASK in the southern Baltic Sea. Measurements were collected for the NASA program Maritime Aerosol Network. Data collected with the DiGICORA III Radiosonde (RS92) come from the webpage of the University of Wyoming, Department of Atmospheric Science. The first instrument, sunphotometer, allows us to collect data on days that are cloud-free. The Microtops II is capable of measuring the total ozone column, total precipitable water vapor and aerosol optical depth at 1020 nm (Morys et al. 2001; Ichoku et al., 2002). Each of these parameters is automatically derived. Data collected by Microtops have been processed with the pre- and post-field calibration and automatic cloud clearing. Precipitable water vapor in the column was derived from the 936nm channel. Detailed data description is available on the AERONET webpage. In radiousoundings the total precipitable water is the water that occurs in a vertical column of a unit cross-sectional area between any two specified levels, commonly expressed as from the earth's surface to the 'top' of the atmosphere. The Integrated Precipitable Water Vapor (IPWV) is the height of liquid water that would result from the condensation of all water vapor in a column. The study of one cruise (29 March - 20 April) shows that 241 Microtops measurements were made, each of

  9. Water vapor movement in freezing aggregate base materials.

    Science.gov (United States)

    2014-06-01

    The objectives of this research were to 1) measure the extent to which water vapor movement results in : water accumulation in freezing base materials; 2) evaluate the effect of soil stabilization on water vapor movement : in freezing base materials;...

  10. Ultraviolet absorption spectrum of hydrogen peroxide vapor. [for atmospheric abundances

    Science.gov (United States)

    Molina, L. T.; Schinke, S. D.; Molina, M. J.

    1977-01-01

    The ultraviolet absorption cross sections of hydrogen peroxide vapor have been determined over the wavelength range 210 to 350 nm at 296 K. At the longer wavelengths, the gas phase absorptivities are significantly larger than the corresponding values in condensed phase. The atmospheric H2O2 photodissociation rate for overhead sun at the earth's surface is estimated to be about 1.3 x 10 to the -5th/sec.

  11. Fossil Fuel Combustion Fingerprint in High-Resolution Urban Water Vapor Isotope Measurements

    Science.gov (United States)

    Gorski, G.; Good, S. P.; Bowen, G. J.

    2014-12-01

    Increasing energy consumption and rapid urbanization have many important and poorly understood consequences for the hydrologic cycle in urban and suburban areas. Wide use of fossil fuels for transportation and heating releases isotopically distinctive water vapor that contributes to the overall water vapor budget in varying, usually unknown, concentrations. The use of long term, high resolution isotopic measurements can help determine different sources and proportions of water vapor at various time scales. We present two months of high-resolution water vapor isotope measurements coupled with CO2 concentrations and co-located meteorological observations from December 2013 - January 2014 in Salt Lake City, UT. Periods of atmospheric stagnation (cold-air inversions) show a buildup of CO2 from baseline values of 420 ppm to as high as 600 ppm and an associated decrease in water vapor deuterium-excess values from a baseline of approx. 10‰ to values as low as -10‰ (where d = δ2H - 8*δ18O, in per mil units). We suggest that the strong relationship between CO2and d during inversion periods is driven by the build-up of fossil fuel combustion-derived water vapor with very low d values (≤ -150‰). Based on our measurements of its isotopic composition, combustion-derived water vapor could contribute as much as 15% to the total water vapor budget during inversion periods. We present evidence of this effect at both the multi-day scale and the diurnal scale, where periods of increased automobile use and home heating can be identified. This study provides the first isotopic evidence that accumulation of water of combustion can be identified in boundary layer water vapor, suggests that an appreciable fraction of boundary layer vapor can be derived from combustion under certain atmospheric conditions, and indicates that the distinctive d values of combustion-derived vapor may be a useful tracer for this component of the atmospheric water budget in other urban regions.

  12. MODIS/Terra Near Real Time (NRT) Temperature and Water Vapor Profiles 5-Min L2 Swath 5km

    Data.gov (United States)

    National Aeronautics and Space Administration — The level-2 MODIS Temperature and Water Vapor Profile Product MOD07_L2 consists of 30 gridded parameters related to atmospheric stability, atmospheric temperature...

  13. MODIS/Aqua Near Real Time (NRT) Temperature and Water Vapor Profiles 5-Min L2 Swath 5km

    Data.gov (United States)

    National Aeronautics and Space Administration — The level-2 MODIS Temperature and Water Vapor Profile Product MYD07_L2 consists of 30 gridded parameters related to atmospheric stability, atmospheric temperature...

  14. Urban emissions of water vapor in winter

    Science.gov (United States)

    Salmon, Olivia E.; Shepson, Paul B.; Ren, Xinrong; Marquardt Collow, Allison B.; Miller, Mark A.; Carlton, Annmarie G.; Cambaliza, Maria O. L.; Heimburger, Alexie; Morgan, Kristan L.; Fuentes, Jose D.; Stirm, Brian H.; Grundman, Robert; Dickerson, Russell R.

    2017-09-01

    Elevated water vapor (H2Ov) mole fractions were occasionally observed downwind of Indianapolis, IN, and the Washington, D.C.-Baltimore, MD, area during airborne mass balance experiments conducted during winter months between 2012 and 2015. On days when an urban H2Ov excess signal was observed, H2Ov emission estimates range between 1.6 × 104 and 1.7 × 105 kg s-1 and account for up to 8.4% of the total (background + urban excess) advected flow of atmospheric boundary layer H2Ov from the urban study sites. Estimates of H2Ov emissions from combustion sources and electricity generation facility cooling towers are 1-2 orders of magnitude smaller than the urban H2Ov emission rates estimated from observations. Instances of urban H2Ov enhancement could be a result of differences in snowmelt and evaporation rates within the urban area, due in part to larger wintertime anthropogenic heat flux and land cover differences, relative to surrounding rural areas. More study is needed to understand why the urban H2Ov excess signal is observed on some days, and not others. Radiative transfer modeling indicates that the observed urban enhancements in H2Ov and other greenhouse gas mole fractions contribute only 0.1°C d-1 to the urban heat island at the surface. This integrated warming through the boundary layer is offset by longwave cooling by H2Ov at the top of the boundary layer. While the radiative impacts of urban H2Ov emissions do not meaningfully influence urban heat island intensity, urban H2Ov emissions may have the potential to alter downwind aerosol and cloud properties.

  15. Applying the Water Vapor Radiometer to Verify the Precipitable Water Vapor Measured by GPS

    Directory of Open Access Journals (Sweden)

    Ta-Kang Yeh

    2014-01-01

    Full Text Available Taiwan is located at the land-sea interface in a subtropical region. Because the climate is warm and moist year round, there is a large and highly variable amount of water vapor in the atmosphere. In this study, we calculated the Zenith Wet Delay (ZWD of the troposphere using the ground-based Global Positioning System (GPS. The ZWD measured by two Water Vapor Radiometers (WVRs was then used to verify the ZWD that had been calculated using GPS. We also analyzed the correlation between the ZWD and the precipitation data of these two types of station. Moreover, we used the observational data from 14 GPS and rainfall stations to evaluate three cases. The offset between the GPS-ZWD and the WVR-ZWD ranged from 1.31 to 2.57 cm. The correlation coefficient ranged from 0.89 to 0.93. The results calculated from GPS and those measured using the WVR were very similar. Moreover, when there was no rain, light rain, moderate rain, or heavy rain, the flatland station ZWD was 0.31, 0.36, 0.38, or 0.40 m, respectively. The mountain station ZWD exhibited the same trend. Therefore, these results have demonstrated that the potential and strength of precipitation in a region can be estimated according to its ZWD values. Now that the precision of GPS-ZWD has been confirmed, this method can eventually be expanded to the more than 400 GPS stations in Taiwan and its surrounding islands. The near real-time ZWD data with improved spatial and temporal resolution can be provided to the city and countryside weather-forecasting system that is currently under development. Such an exchange would fundamentally improve the resources used to generate weather forecasts.

  16. Vaporization of fault water during seismic slip

    Science.gov (United States)

    Chen, Jianye; Niemeijer, André R.; Fokker, Peter A.

    2017-06-01

    Laboratory and numerical studies, as well as field observations, indicate that phase transitions of pore water might be an important process in large earthquakes. We present a model of the thermo-hydro-chemo-mechanical processes, including a two-phase mixture model to incorporate the phase transitions of pore water, occurring during fast slip (i.e., a natural earthquake) in order to investigate the effects of vaporization on the coseismic slip. Using parameters from typical natural faults, our modeling shows that vaporization can indeed occur at the shallow depths of an earthquake, irrespective of the wide variability of the parameters involved (sliding velocity, friction coefficient, gouge permeability and porosity, and shear-induced dilatancy). Due to the fast kinetics, water vaporization can cause a rapid slip weakening even when the hydrological conditions of the fault zone are not favorable for thermal pressurization, e.g., when permeability is high. At the same time, the latent heat associated with the phase transition causes the temperature rise in the slip zone to be buffered. Our parametric analyses reveal that the amount of frictional work is the principal factor controlling the onset and activity of vaporization and that it can easily be achieved in earthquakes. Our study shows that coseismic pore fluid vaporization might have played important roles at shallow depths of large earthquakes by enhancing slip weakening and buffering the temperature rise. The combined effects may provide an alternative explanation for the fact that low-temperature anomalies were measured in the slip zones at shallow depths of large earthquakes.

  17. Advancements in water vapor electrolysis technology. [for Space Station ECLSS

    Science.gov (United States)

    Chullen, Cinda; Heppner, Dennis B.; Sudar, Martin

    1988-01-01

    The paper describes a technology development program whose goal is to develop water vapor electrolysis (WVE) hardware that can be used selectively as localized topping capability in areas of high metabolic activity without oversizing the central air revitalization system on long-duration manned space missions. The WVE will be used primarily to generate O2 for the crew cabin but also to provide partial humidity control by removing water vapor from the cabin atmosphere. The electrochemically based WVE interfaces with cabin air which is controlled in the following ranges: dry bulb temperature of 292 to 300 K; dew point temperature of 278 to 289 K; relative humidity of 25 to 75 percent; and pressure of 101 + or - 1.4 kPa. Design requirements, construction details, and results for both single-cell and multicell module testing are presented, and the preliminary sizing of a multiperson subsystem is discussed.

  18. Quality and Control of Water Vapor Winds

    Science.gov (United States)

    Jedlovec, Gary J.; Atkinson, Robert J.

    1996-01-01

    Water vapor imagery from the geostationary satellites such as GOES, Meteosat, and GMS provides synoptic views of dynamical events on a continual basis. Because the imagery represents a non-linear combination of mid- and upper-tropospheric thermodynamic parameters (three-dimensional variations in temperature and humidity), video loops of these image products provide enlightening views of regional flow fields, the movement of tropical and extratropical storm systems, the transfer of moisture between hemispheres and from the tropics to the mid- latitudes, and the dominance of high pressure systems over particular regions of the Earth. Despite the obvious larger scale features, the water vapor imagery contains significant image variability down to the single 8 km GOES pixel. These features can be quantitatively identified and tracked from one time to the next using various image processing techniques. Merrill et al. (1991), Hayden and Schmidt (1992), and Laurent (1993) have documented the operational procedures and capabilities of NOAA and ESOC to produce cloud and water vapor winds. These techniques employ standard correlation and template matching approaches to wind tracking and use qualitative and quantitative procedures to eliminate bad wind vectors from the wind data set. Techniques have also been developed to improve the quality of the operational winds though robust editing procedures (Hayden and Veldon 1991). These quality and control approaches have limitations, are often subjective, and constrain wind variability to be consistent with model derived wind fields. This paper describes research focused on the refinement of objective quality and control parameters for water vapor wind vector data sets. New quality and control measures are developed and employed to provide a more robust wind data set for climate analysis, data assimilation studies, as well as operational weather forecasting. The parameters are applicable to cloud-tracked winds as well with minor

  19. Raman lidar measurements of water vapor and aerosols during the atmospheric radiation measurement (ARM) remote clouds sensing (RCS) intensive observation period (IOP)

    Energy Technology Data Exchange (ETDEWEB)

    Melfi, S.H.; Starr, D.O`C.; Whiteman, D. [NASA Goddard Space Flight Center, Greenbelt, MD (United States)] [and others

    1996-04-01

    The first Atmospheric Radiation Measurement (ARM) remote Cloud Study (RCS) Intensive Operations Period (IOP) was held during April 1994 at the Southern Great Plains (SGP) site. This experiment was conducted to evaluate and calibrate state-of-the-art, ground based remote sensing instruments and to use the data acquired by these instruments to validate retrieval algorithms developed under the ARM program.

  20. Permeability of MDT chambers to water vapor

    CERN Document Server

    Palestini, S

    2003-01-01

    Tests of MDT chambers performed at the GIF facility and in the H8 test-beam area have shown relative high levels of water vapor contamination in the gas-mixture at the detector output. This effects significantly the drift properties of the MDTs. This note shows that amount of water observed is compatible with approximate estimates based on the permeability of Noryl, used in the tube end-plugs, and of EPDM, used in the O-rings of the on-chamber gas distribution.

  1. Water Vapor Effects on Silica-Forming Ceramics

    Science.gov (United States)

    Opila, E. J.; Greenbauer-Seng, L. (Technical Monitor)

    2000-01-01

    Silica-forming ceramics such as SiC and Si3N4 are proposed for applications in combustion environments. These environments contain water vapor as a product of combustion. Oxidation of silica-formers is more rapid in water vapor than in oxygen. Parabolic oxidation rates increase with the water vapor partial pressure with a power law exponent value close to one. Molecular water vapor is therefore the mobile species in silica. Rapid oxidation rates and large amounts of gases generated during the oxidation reaction in high water vapor pressures may result in bubble formation in the silica and nonprotective scale formation. It is also shown that silica reacts with water vapor to form Si(OH)4(g). Silica volatility has been modeled using a laminar flow boundary layer controlled reaction equation. Silica volatility depends on the partial pressure of water vapor, the total pressure, and the gas velocity. Simultaneous oxidation and volatilization reactions have been modeled with paralinear kinetics.

  2. The observed day-to-day variability of Mars water vapor

    Science.gov (United States)

    Jakosky, Bruce M.; Lapointe, Michael R.; Zurek, Richard W.

    1987-01-01

    The diurnal variability of atmospheric water vapor as derived from the Viking MAWD data is discussed. The detection of day to day variability of atmospheric water would be a significant finding since it would place constraints on the nature of surface reservoirs. Unfortunately, the diurnal variability seen by the MAWD experiment is well correlated with the occurrence of dust and/or ice hazes, making it difficult to separate real variations from observational effects. Analysis of the day to day variability of water vapor in the Martian atmosphere suggests that the observations are, at certain locations and seasons, significantly affected by the presence of water-ice hazes. Because such effects are generally limited to specific locations, such as Tharsis, Lunae Planum, and the polar cap edge during the spring, the seasonal and latitudinal trends in water vapor that have been previously reported are not significantly affected.

  3. Nd:Glass-Raman laser for water vapor dial

    Science.gov (United States)

    Kagann, R. H.; Petheram, J. C.; Rosenberg, A.

    1986-01-01

    A tunable solid-state Raman shifted laser which was used in a water vapor Differential Absorption Lidar (DIAL) system at 9400 A is described. The DIAL transmitter is based on a tunable glass laser operating at 1.06 microns, a hydrogen Raman cell to shift the radiation to 1.88 microns, and a frequency doubling crystal. The results of measurements which characterize the output of the laser with respect to optimization of optical configuration and of Raman parameters were reported. The DIAL system was also described and preliminary atmospheric returns shown.

  4. Millimeter-wave Radiometer for High Sensitivity Water Vapor Profiling in Arid Regions

    Energy Technology Data Exchange (ETDEWEB)

    Pazmany, Andrew

    2006-11-09

    Abstract - ProSensing Inc. has developed a G-band (183 GHz) water Vapor Radiometer (GVR) for long-term, unattended measurements of low concentrations of atmospheric water vapor and liquid water. Precipitable water vapor and liquid water path are estimated from zenith brightness temperatures measured from four double-sideband receiver channels, centered at 183.31 1, 3 and 7, and 14 GHz. A prototype ground-based version of the instrument was deployed at the DOE ARM program?s North Slope of Alaska site near Barrow AK in April 2005, where it collected data continuously for one year. A compact, airborne version of this instrument, packaged to operate from a standard 2-D PMS probe canister, has been tested on the ground and is scheduled for test flights in the summer of 2006. This paper presents design details, laboratory test results and examples of retrieved precipitable water vapor and liquid water path from measured brightness temperature data.

  5. The rate of water vapor evaporation from ice substrates in the presence of HCl and HBr: implications for the lifetime of atmospheric ice particles

    Directory of Open Access Journals (Sweden)

    C. Delval

    2003-01-01

    Full Text Available Using a multidiagnostic approach the rate Rev [ molec cm-3 s-1] or flux Jev [ molec cm-2 s-1] of evaporation of H2O and its corresponding rate constant for condensation, kcond [s-1 ], on a 1 µm thick ice film have been studied in the temperature range 190 to 240 K as well as in the presence of small amounts of HCl and HBr that left the vapor pressure of H2O on ice unchanged. The resulting Arrhenius expressions for pure ice are Jev = 1.6 · 10 28 ± 1 · exp  (- 10.3 ± 1.2/ RT  [ molec cm-2 s-1] , kcond = 1.7 · 10 - 2 ± 1 · exp  (+ 1.6 ± 1.5/ RT [s -1], in the presence of a HCl mole fraction in the range 3.2 · 10 - 5 - 6.4 · 10 - 3 : Jev = 6.4 · 10 26 ± 1 · exp  (- 9.7 ± 1.2/ RT  [ molec cm-2 s-1] , kcond = 2.8 · 10 - 2 ± 1 · exp ( + 1.5 ± 1.6 /RT  [s -1], and a HBr mole fraction smaller than 6.4 · 10 - 3 : Jev = 7.4 · 10 25 ± 1 · exp ( - 9.1 ± 1.2 /RT  [ molec cm-2 s-1] , kcond = 7.1 · 10 - 5 ± 1 · exp (+ 2.6 ± 1.5/ RT [s -1]. The small negative activation energy for H2O condensation on ice points to a precursor mechanism. The corresponding enthalpy of sublimation is DHsubl = Eev - Econd = 11.9 ± 2.7 kcal mol-1 , DHsubl = 11.2 ± 2.8 kcal mol-1, and DHsubl = 11.7 ± 2.8 kcal mol-1 whose values are identical within experimental uncertainty to the accepted literature value of 12.3 kcal mol-1 . Interferometric data at 633 nm and FTIR absorption spectra in transmission support the kinetic results. The data are consistent with a significant lifetime enhancement for HCl- and HBr-contaminated ice particles by a factor of 3–6 and 10–20, respectively, for submonolayer coverages of HX once the fraction of the ice not contaminated by HX has evaporated.

  6. MODIS/Aqua Near Real Time (NRT) Total Precipitable Water Vapor 5-Min L2 Swath 1km and 5km

    Data.gov (United States)

    National Aeronautics and Space Administration — The MODIS level-2 atmospheric precipitable water product consists of total atmospheric column water vapor amounts (and ancillary parameters) over clear land areas of...

  7. Synthesis of double oxides TiO2-SiO2 with low titanium content by hydrolysis of tetrabutoxytitanium-tetraethoxysilane mixture in an atmosphere of water vapor and ammonia

    OpenAIRE

    Shishmakov, A. B.; Koryakova, O. V.; Seleznev, A. S.; Petrov, L. A.; Melkozerov, S. A.

    2013-01-01

    A series of TiO2-SiO2 binary xerogels with the titanium content lower than 7 mol % were prepared by joint hydrolysis of tetrabutoxytitanium and tetraethoxysilane in a desiccator in the atmosphere of vapor over 5% aqueous NH3 solution under static conditions. The physicochemical properties of the material were examined by IR spectroscopy and by the kinetic method with hydrogen peroxide decomposition as model reaction. © 2013 Pleiades Publishing, Ltd.

  8. The Annual Cycle of Water Vapor on Mars as Observed by the Thermal Emission Spectrometer

    Science.gov (United States)

    Smith, Michael D.; Vondrak, Richard R. (Technical Monitor)

    2001-01-01

    Spectra taken by the Mars Global Surveyor Thermal Emission Spectrometer (TES) have been used to monitor the latitude, longitude, and seasonal dependence of water vapor for over one full Martian year (March 1999-March 2001). A maximum in water vapor abundance is observed at high latitudes during mid-summer in both hemispheres, reaching a maximum value of approximately 100 pr-micrometer in the north and approximately 50 pr-micrometer in the south. Low water vapor abundance (water vapor. The latitudinal and seasonal dependence of the decay of the northern summer water vapor maximum implies cross-equatorial transport of water to the southern hemisphere, while there is little or no corresponding transport during the decay of the southern hemisphere summer maximum. The latitude-longitude dependence of annually-averaged water vapor (corrected for topography) has a significant positive correlation with albedo and significant negative correlations with thermal inertia and surface pressure. Comparison of TES results with those retrieved from the Viking Orbiter Mars Atmospheric Water Detectors (MAWD) experiments shows some similar features, but also many significant differences. The southern hemisphere maximum observed by TES was not observed by MAWD and the large latitudinal gradient in annually-averaged water vapor observed by MAWD does not appear in the TES results.

  9. Raman lidar water vapor profiling over Warsaw, Poland

    Science.gov (United States)

    Stachlewska, Iwona S.; Costa-Surós, Montserrat; Althausen, Dietrich

    2017-09-01

    Water vapor mixing ratio and relative humidity profiles were derived from the multi-wavelength Raman PollyXT lidar at the EARLINET site in Warsaw, using the Rayleigh molecular extinction calculation based on atmospheric temperature and pressure from three different sources: i) the standard atmosphere US 62, ii) the Global Data Assimilation System (GDAS) model output, and iii) the WMO 12374 radiosoundings launched at Legionowo. With each method, 136 midnight relative humidity profiles were obtained for lidar observations from July 2013 to August 2015. Comparisons of these profiles showed in favor of the latter method (iii), but it also indicated that the other two data sources could replace it, if necessary. Such use was demonstrated for an automated retrieval of water vapor mixing ratio from dusk until dawn on 19/20 March 2015; a case study related to an advection of biomass burning aerosol from forest fires over Ukraine. Additionally, an algorithm that applies thresholds to the radiosounding relative humidity profiles to estimate macro-physical cloud vertical structure was used for the first time on the Raman lidar relative humidity profiles. The results, based on a subset of 66 profiles, indicate that below 6 km cloud bases/tops can be successfully obtained in 53% and 76% cases from lidar and radiosounding profiles, respectively. Finally, a contribution of the lidar derived mean relative humidity to cloudy conditions within the range of 0.8 to 6.2 km, in comparison to clear-sky conditions, was estimated.

  10. Mesospheric water vapor. Variability at different timescales observed by ground-based microwave spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Hallgren, Kristofer

    2011-07-01

    The importance of water vapor in Earth's atmosphere cannot be understated. It is an active green-house gas, important energy conveyer in the troposhere and a key element in many chemical reactions in the middle atmosphere. Yet, there are still many questions concerning the water vapor dynamics in the middle atmosphere. This thesis present a new, state-of-the art, microwave instrument developed in order to shed light on some of these issues. The high sensitivity and time-resolution enable us to resolve fast dynamical events which was not possible before. Furthermore it expands an already long dataset and a mean vertical distribution of water vapor for polar latitudes is presented. (orig.)

  11. Dissolution kinetics of volatile organic compound vapors in water : An integrated experimental and computational study

    NARCIS (Netherlands)

    G. Mahmoodlu, Mojtaba; Pontedeiro, Elizabeth M.; Pérez Guerrero, Jesús S.; Raoof, Amir; Hassanizadeh, S. Majid; van Genuchten, Martinus Th

    In this study we performed batch experiments to investigate the dissolution kinetics of trichloroethylene (TCE) and toluene vapors in water at room temperature and atmospheric pressure. The batch systems consisted of a water reservoir and a connected headspace, the latter containing a small glass

  12. Distribution Analysis of Multi GNSS Slant Delays and Simulated Water Vapor Tomography in Yangtze River Delta

    Directory of Open Access Journals (Sweden)

    WANG Wei

    2016-02-01

    Full Text Available Currently, the GNSS network of Yangtze River delta has being applied to monitor the water vapor above this region and research water vapor tomography. Studies have shown that the dictances between stations are large and inhomogeneous, that will make it difficult to get the high tomography precision. Therefore, a simulation test of multi GNSS observations on tomography is introduced. The multi GNSS observations are more homogeneous in spatial distribution than a single positioning system, which can reduce the space rate of the grid, especially increase the number of the grid with information at middle and high layers. The multi GNSS observation can provide more and better water vapor information which can patch up deficiency of a single positioning system. A simulated water vapor tomography is carried out, and the result shows that the multi GNSS observations could improve the accuracy of tomography, especially above the 5 km height layer of the atmosphere.

  13. Water vapor sorption hysteresis of ceramic bricks

    Science.gov (United States)

    Koronthalyova, Olga

    2016-07-01

    A quantification of the hysteretic effects and their thorough analysis was carried out for three types of ceramic bricks. Water vapor adsorption/desorption isotherms were measured by the standard desiccator method. The desorption measurements were carried out from capillary moisture content as well as from equilibrium moisture content corresponding to the relative humidity of 98 %. For all three tested types of bricks the hysteretic effects were present but their significance differed depending on the particular type of brick. Significant differences were noticed also in desorption curves determined from capillary moisture content and from equilibrium moisture content corresponding to the relative humidity of 98 %. Based on the measured data a possible correlation between pore structure parameters and noticed hysteretic effects as well as relevance of the open pore model are discussed. The obtained adsorption/desorption curves were approximated by an analytical relation.

  14. Water recovery by catalytic treatment of urine vapor

    Science.gov (United States)

    Budininkas, P.; Quattrone, P. D.; Leban, M. I.

    1980-01-01

    The objective of this investigation was to demonstrate the feasibility of water recovery on a man-rated scale by the catalytic processing of untreated urine vapor. For this purpose, two catalytic systems, one capable of processing an air stream containing low urine vapor concentrations and another to process streams with high urine vapor concentrations, were designed, constructed, and tested to establish the quality of the recovered water.

  15. Operating a radio-frequency plasma source on water vapor.

    Science.gov (United States)

    Nguyen, Sonca V T; Foster, John E; Gallimore, Alec D

    2009-08-01

    A magnetically enhanced radio-frequency (rf) plasma source operating on water vapor has an extensive list of potential applications. In this work, the use of a rf plasma source to dissociate water vapor for hydrogen production is investigated. This paper describes a rf plasma source operated on water vapor and characterizes its plasma properties using a Langmuir probe, a residual gas analyzer, and a spectrometer. The plasma source operated first on argon and then on water vapor at operating pressures just over 300 mtorr. Argon and water vapor plasma number densities differ significantly. In the electropositive argon plasma, quasineutrality requires n(i) approximately = n(e), where n(i) is the positive ion density. But in the electronegative water plasma, quasineutrality requires n(i+) = n(i-) + n(e). The positive ion density and electron density of the water vapor plasma are approximately one and two orders of magnitude lower, respectively, than those of argon plasma. These results suggest that attachment and dissociative attachment are present in electronegative water vapor plasma. The electron temperature for this water vapor plasma source is between 1.5 and 4 eV. Without an applied axial magnetic field, hydrogen production increases linearly with rf power. With an axial magnetic field, hydrogen production jumps to a maximum value at 500 W and then saturates with rf power. The presence of the applied axial magnetic field is therefore shown to enhance hydrogen production.

  16. The interpretation of data from the Viking Mars Atmospheric Water Detectors (MAWD): Some points for discussion

    Science.gov (United States)

    Clifford, Stephen M.

    1988-01-01

    Properly interpreted, water vapor column abundance measurements can provide important insights into many of the processes that govern the diurnal, seasonal, and climatic cycles of atmospheric water on Mars. The uncertain distribution of water vapor complicates this analysis. It is argued that if a significant fraction of the total atmospheric vapor content is concentrated within the lowermost scale height, then the hemispheric asymmetry in zonally averaged topography/air mass might itself explain the observed gradient in the annual and zonally averaged vapor abundance.

  17. An optical water vapor sensor for unmanned aerial vehicles

    Energy Technology Data Exchange (ETDEWEB)

    Timothy A. Berkoff; Paul L. Kebabian; Robert A. McClatchy; Charles E. Kolb; Andrew Freedman

    1998-12-01

    The water vapor sensor developed by Aerodyne Research, based on the optical absorption of light at {approximately}935 nm, has been successfully demonstrated on board the Pacific Northwest National Laboratory's Gulfstream-1 research aircraft during the Department of Energy's ARM Intensive Operations Period in August 1998. Data taken during this field campaign show excellent agreement with a chilled mirror and Lyman-alpha hygrometers and measurements confirm the ability to measure rapid, absolute water vapor fluctuations with a high degree of instrument stability and accuracy, with a noise level as low 10 ppmv (1 Hz measurement bandwidth). The construction of this small, lightweight sensor contains several unique elements which result in several significant advantages when compared to other techniques. First, the low power consumption Argon discharge lamp provides an optical beam at a fixed wavelength without a need for temperature or precision current control. The multi-pass absorption cell developed for this instrument provides a compact, low cost method that can survive deployment in the field. Fiber-optic cables, which are used to convey to light between the absorption cell, light source, and detection modules enable remote placement of the absorption cell from the opto-electronics module. Finally, the sensor does not use any moving parts which removes a significant source of potential malfunction. The result is an instrument which maintained its calibration throughout the field measurement campaign, and was not affected by high vibration and large uncontrolled temperature excursions. We believe that the development of an accurate, fast response water vapor monitor described in this report will open up new avenues of aerial-vehicle-based atmospheric research which have been relatively unexplored due to the lack of suitable low-cost, light-weight instrumentation.

  18. Atmospheric Water-Cycle Regimes and Cloud Regimes

    Science.gov (United States)

    Wong, S.; Fetzer, E. J.; L'Ecuyer, T. S.

    2013-12-01

    The relationship between the atmospheric water vapor budget and cloud properties is investigated by collocated reanalysis fields from Modern Era Retrospective-analysis for Research and Applications (MERRA) and the observations from the Moderate Resolution Imaging Spectroradiometer (MODIS) satellite instrument. Intensities of surface water exchange (precipitation minus evaporation) are analyzed in the space of 'dynamical regimes', which are defined by combination of large-scale water vapor advection and convergence calculated from the MERRA. The atmospheric water vapor sinks associated with mid-latitude storm systems and precipitation in the west coast of United States are mainly driven by the large-scale dynamical advection, while those associated with tropical deep convection and summertime monsoons are mainly driven by water vapor convergence. Subtropical subsidence area over the eastern ocean basins is dominated by strong water vapor divergence. These dynamical regimes are then connected to the collocated MODIS cloud top pressure and cloud optical thickness. Probability density distributions of these MODIS cloud properties associated with each dynamical regime will be presented.

  19. Water vapor and Gas Transport through Polymeric Membranes

    NARCIS (Netherlands)

    Metz, S.J.

    2003-01-01

    Water vapor transport through polymeric materials plays an important role in a large number of applications such as: food packaging, breathable clothing, roofing membranes, diapers, and the removal of water vapor from gas streams (e.g. dehydration of natural gas or the drying of compressed air).

  20. A New Technique for the Retrieval of Near Surface Water Vapor Using DIAL Measurements

    Science.gov (United States)

    Ismail, Syed; Kooi, Susan; Ferrare, Richard; Winker, David; Hair, Johnathan; Nehrir, Amin; Notari, Anthony; Hostetler, Chris

    2015-01-01

    Water vapor is one of the most important atmospheric trace gas species and influences radiation, climate, cloud formation, surface evaporation, precipitation, storm development, transport, dynamics, and chemistry. For improvements in NWP (numerical weather prediction) and climate studies, global water vapor measurements with higher accuracy and vertical resolution are needed than are currently available. Current satellite sensors are challenged to characterize the content and distribution of water vapor in the Boundary Layer (BL) and particularly near the first few hundred meters above the surface within the BL. These measurements are critically needed to infer surface evaporation rates in cloud formation and climate studies. The NASA Langley Research Center Lidar Atmospheric Sensing Experiment (LASE) system, which uses the Differential Absorption Lidar (DIAL) technique, has demonstrated the capability to provide high quality water vapor measurements in the BL and across the troposphere. A new retrieval technique is investigated to extend these DIAL water vapor measurements to the surface. This method uses signals from both atmospheric backscattering and the strong surface returns (even over low reflectivity oceanic surfaces) using multiple gain channels to cover the large signal dynamic range. Measurements can be made between broken clouds and in presence of optically thin cirrus. Examples of LASE measurements from a variety of conditions encountered during NASA hurricane field experiments over the Atlantic Ocean are presented. Comparisons of retrieved water vapor profiles from LASE near the surface with dropsonde measurements show very good agreement. This presentation also includes a discussion of the feasibility of developing space-based DIAL capability for high resolution water vapor measurements in the BL and above and an assessment of the technology needed for developing this capability.

  1. Terrestrial atmosphere, water and astrobiology

    Directory of Open Access Journals (Sweden)

    Coradini M.

    2010-12-01

    Full Text Available Primitive life, defined as a chemical system capable to transfer its molecular information via self-replication and also capable to evolve, originated about 4 billion years ago from the processing of organic molecules by liquid water. Terrestrial atmosphere played a key role in the process by allowing the permanent presence of liquid water and by participating in the production of carbon-based molecules. Water molecules exhibit specific properties mainly due to a dense network of hydrogen bonds. The carbon-based molecules were either home made in the atmosphere and/or in submarine hydrothermal systems or delivered by meteorites and micrometeorites. The search for possible places beyond the earth where the trilogy atmosphere/water/life could exist is the main objective of astrobiology. Within the Solar System, exploration missions are dedicated to Mars, Europa, Titan and the icy bodies. The discovery of several hundreds of extrasolar planets opens the quest to the whole Milky Way.

  2. Melt-vapor phase transition in the lead-selenium system at atmospheric and low pressure

    Science.gov (United States)

    Volodin, V. N.; Burabaeva, N. M.; Trebukhov, S. A.

    2016-03-01

    The boiling temperature and the corresponding vapor phase composition in the existence domain of liquid solutions were calculated from the partial pressures of saturated vapor of the components and lead selenide over liquid melts in the lead-selenium system. The phase diagram was complemented with the liquid-vapor phase transition at atmospheric pressure and in vacuum of 100 Pa, which allowed us to judge the behavior of the components during the distillation separation.

  3. Water Vapor in the Protoplanetary Disk of DG Tau

    NARCIS (Netherlands)

    Podio, L.; Kamp, I.; Codella, C.; Cabrit, S.; Nisini, B.; Dougados, C.; Sandell, G.; Williams, J. P.; Testi, L.; Thi, W. -F.; Woitke, P.; Meijerink, R.; Spaans, M.; Aresu, G.; Menard, F.; Pinte, C.

    2013-01-01

    Water is key in the evolution of protoplanetary disks and the formation of comets and icy/water planets. While high-excitation water lines originating in the hot inner disk have been detected in several T Tauri stars (TTSs), water vapor from the outer disk, where most water ice reservoirs are

  4. Adsorption and Desorption of Nitrogen and Water Vapor by clay

    Science.gov (United States)

    Cui, Deshan; Chen, Qiong; Xiang, Wei; Huang, Wei

    2015-04-01

    Adsorption and desorption of nitrogen and water vapor by clay has a significant impact on unsaturated soil physical and mechanical properties. In order to study the adsorption and desorption characteristics of nitrogen and water vapor by montmorillonite, kaolin and sliding zone soils, the Autosorb-iQ specific surface area and pore size analyzer instrument of United State was taken to carry out the analysis test. The adsorption and desorption of nitrogen at 77K and water vapor at 293K on clay sample were conducted. The theories of BET, FHH and hydration energy were taken to calculate the specific surface, surface fractal dimension and adsorption energy. The results show that the calculated specific surface of water vapor by clay is bigger than nitrogen adsorption test because clay can adsorb more water vapor molecule than nitrogen. Smaller and polar water vapor molecule can access the micropore and then adsorb on the mineral surface and mineral intralayer, which make the mineral surface cations hydrate and the mineral surface smoother. Bigger and nonpolar nitrogen molecule can not enter into the micropore as water vapor molecule and has weak interaction with clay surface.

  5. RAMAN LIDAR PROFILING OF WATER VAPOR AND AEROSOLS OVER THE ARM SGP SITE.

    Energy Technology Data Exchange (ETDEWEB)

    FERRARE,R.A.

    2000-01-09

    We have developed and implemented automated algorithms to retrieve profiles of water vapor mixing ratio, aerosol backscattering, and aerosol extinction from Southern Great Plains (SGP) Cloud and Radiation Testbed (CART) Raman Lidar data acquired during both daytime and nighttime operations. This Raman lidar system is unique in that it is turnkey, automated system designed for unattended, around-the-clock profiling of water vapor and aerosols (Goldsmith et al., 1998). These Raman lidar profiles are important for determining the clear-sky radiative flux, as well as for validating the retrieval algorithms associated with satellite sensors. Accurate, high spatial and temporal resolution profiles of water vapor are also required for assimilation into mesoscale models to improve weather forecasts. We have also developed and implemented routines to simultaneously retrieve profiles of relative humidity. These routines utilize the water vapor mixing ratio profiles derived from the Raman lidar measurements together with temperature profiles derived from a physical retrieval algorithm that uses data from a collocated Atmospheric Emitted Radiance Interferometer (AERI) and the Geostationary Operational Environmental Satellite (GOES) (Feltz et al., 1998; Turner et al., 1999). These aerosol and water vapor profiles (Raman lidar) and temperature profiles (AERI+GOES) have been combined into a single product that takes advantage of both active and passive remote sensors to characterize the clear sky atmospheric state above the CART site.

  6. Raman lidar profiling of water vapor and aerosols over the ARM SGP Site

    Energy Technology Data Exchange (ETDEWEB)

    Ferrare, R.A.

    2000-01-09

    The authors have developed and implemented automated algorithms to retrieve profiles of water vapor mixing ratio, aerosol backscattering, and aerosol extinction from Southern Great Plains (SGP) Cloud and Radiation Testbed (CART) Raman Lidar data acquired during both daytime and nighttime operations. The Raman lidar sytem is unique in that it is turnkey, automated system designed for unattended, around-the-clock profiling of water vapor and aerosols. These Raman lidar profiles are important for determining the clear-sky radiative flux, as well as for validating the retrieval algorithms associated with satellite sensors. Accurate, high spatial and temporal resolution profiles of water vapor are also required for assimilation into mesoscale models to improve weather forecasts. The authors have also developed and implemented routines to simultaneously retrieve profiles of relative humidity. These routines utilize the water vapor mixing ratio profiles derived from the Raman lidar measurements together with temperature profiles derived from a physical retrieval algorithm that uses data from a collocated Atmospheric Emitted Radiance Interferometer (AERI) and the Geostationary Operational Environmental Satellite (GOES). These aerosol and water vapor profiles (Raman lidar) and temperature profiles (AERI+GOES) have been combined into a single product that takes advantage of both active and passive remote sensors to characterize the clear sky atmospheric state above the CART site.

  7. Optimization of GPS water vapor tomography technique with radiosonde and COSMIC historical data

    Directory of Open Access Journals (Sweden)

    S. Ye

    2016-09-01

    Full Text Available The near-real-time high spatial resolution of atmospheric water vapor distribution is vital in numerical weather prediction. GPS tomography technique has been proved effectively for three-dimensional water vapor reconstruction. In this study, the tomography processing is optimized in a few aspects by the aid of radiosonde and COSMIC historical data. Firstly, regional tropospheric zenith hydrostatic delay (ZHD models are improved and thus the zenith wet delay (ZWD can be obtained at a higher accuracy. Secondly, the regional conversion factor of converting the ZWD to the precipitable water vapor (PWV is refined. Next, we develop a new method for dividing the tomography grid with an uneven voxel height and a varied water vapor layer top. Finally, we propose a Gaussian exponential vertical interpolation method which can better reflect the vertical variation characteristic of water vapor. GPS datasets collected in Hong Kong in February 2014 are employed to evaluate the optimized tomographic method by contrast with the conventional method. The radiosonde-derived and COSMIC-derived water vapor densities are utilized as references to evaluate the tomographic results. Using radiosonde products as references, the test results obtained from our optimized method indicate that the water vapor density accuracy is improved by 15 and 12 % compared to those derived from the conventional method below the height of 3.75 km and above the height of 3.75 km, respectively. Using the COSMIC products as references, the results indicate that the water vapor density accuracy is improved by 15 and 19 % below 3.75 km and above 3.75 km, respectively.

  8. SHOULD LATITUDINAL ATMOSPHERIC TRACE VAPOR CONCENTRATIONS BE REPORTED ON A MASS DENSITY BASIS?

    Science.gov (United States)

    For the past several decades the issue of global atmospheric trace vapor migration has been of concern to environmental professionals concerned with global distillation/cold condensation of toxic compounds, contamination of remote ecosystems, global climate change and stratospher...

  9. Modeling chemical vapor deposition of silicon dioxide in microreactors at atmospheric pressure

    NARCIS (Netherlands)

    Konakov, S.A.; Krzhizhanovskaya, V.V.

    2015-01-01

    We developed a multiphysics mathematical model for simulation of silicon dioxide Chemical Vapor Deposition (CVD) from tetraethyl orthosilicate (TEOS) and oxygen mixture in a microreactor at atmospheric pressure. Microfluidics is a promising technology with numerous applications in chemical synthesis

  10. Isobaric vapor-liquid equilibria of water + ethanol + hexyl acetate

    Energy Technology Data Exchange (ETDEWEB)

    Arce, A.; Soto, A. [Univ. of Santiago de Compostela (Spain). Chemical Engineering Dept.; Orge, B.; Tojo, J. [Univ. of Vigo (Spain). Chemical Engineering Dept.

    1995-09-01

    The authors determined the isobaric vapor-liquid equilibrium data for the ternary system water + ethanol + hexyl acetate at 101.325 kPa using a distillation apparatus recycling both liquid and vapor phases. The results were compared with those predicted using group contribution methods. The UNIFAC method gave the best predictions.

  11. Atmospheric Water Balance and Variability in the MERRA-2 Reanalysis

    Science.gov (United States)

    Bosilovich, Michael G.; Robertson, Franklin R.; Takacs, Lawrence; Molod, Andrea; Mocko, David

    2017-01-01

    Closing and balancing Earths global water cycle remains a challenge for the climate community. Observations are limited in duration, global coverage, and frequency, and not all water cycle terms are adequately observed. Reanalyses aim to fill the gaps through the assimilation of as many atmospheric water vapor observations as possible. Former generations of reanalyses have demonstrated a number of systematic problems that have limited their use in climate studies, especially regarding low-frequency trends. This study characterizes the NASA Modern-Era Retrospective Analysis for Research and Applications version 2 (MERRA-2) water cycle relative to contemporary reanalyses and observations. MERRA-2 includes measures intended to minimize the spurious global variations related to in homogeneity in the observational record. The global balance and cycling of water from ocean to land is presented, with special attention given to the water vapor analysis increment and the effects of the changing observing system. While some systematic regional biases can be identified,MERRA-2 produces temporally consistent time series of total column water and transport of water from ocean to land. However, the interannual variability of ocean evaporation is affected by the changing surface-wind-observing system, and precipitation variability is closely related to the evaporation. The surface energy budget is also strongly influenced by the interannual variability of the ocean evaporation. Furthermore, evaluating the relationship of temperature and water vapor indicates that the variations of water vapor with temperature are weaker in satellite data reanalyses, not just MERRA-2, than determined by observations, atmospheric models, or reanalyses without water vapor assimilation.

  12. Mars: Water Vapor Observations from the Viking Orbiters

    Science.gov (United States)

    Farmer, C. B.; Davies, D. W.; Holland, A. L.; Laporte, D. D.; Doms, P. E.

    1977-01-01

    The global distribution of the water vapor has been mapped at low resolution throughout the period from the northern summer solstice to the following equinox. During this seasonal period the water vapor underwent a gradual redistribution, the latitude of maximum column abundance moving from the northern polar area to the equatorial latitudes. The total global vapor content remained approximately constant at the equivalent of about 1.3 cu km of ice. The various data obtained indicate that the residual polar caps are composed of water ice.

  13. Static Water Vapor Feed Electrolyzer Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Development of a static vapor feed electrolyzer utilizing an advanced bipolar plate that produces sub-saturated H2 and O2 is proposed. This novel bipolar design can...

  14. Compact Water Vapor Exchanger for Regenerative Life Support Systems

    Science.gov (United States)

    Izenson, Michael G.; Chen, Weibo; Anderson, Molly; Hodgson, Edward

    2012-01-01

    Thermal and environmental control systems for future exploration spacecraft must meet challenging requirements for efficient operation and conservation of resources. Regenerative CO2 removal systems are attractive for these missions because they do not use consumable CO2 absorbers. However, these systems also absorb and vent water to space along with carbon dioxide. This paper describes an innovative device designed to minimize water lost from regenerative CO2 control systems. Design studies and proof-of-concept testing have shown the feasibility of a compact, efficient membrane water vapor exchanger (WVX) that will conserve water while meeting challenging requirements for operation on future spacecraft. Compared to conventional WVX designs, the innovative membrane WVX described here has the potential for high water recovery efficiency, compact size, and very low pressure losses. The key innovation is a method for maintaining highly uniform flow channels in a WVX core built from water-permeable membranes. The proof-of-concept WVX incorporates all the key design features of a prototypical unit, except that it is relatively small scale (1/23 relative to a unit sized for a crew of six) and some components were fabricated using non-prototypical methods. The proof-of-concept WVX achieved over 90% water recovery efficiency in a compact core in good agreement with analysis models. Furthermore the overall pressure drop is very small (less than 0.5 in. H2O, total for both flow streams) and meets requirements for service in environmental control and life support systems on future spacecraft. These results show that the WVX provides very uniform flow through flow channels for both the humid and dry streams. Measurements also show that CO2 diffusion through the water-permeable membranes will have negligible effect on the CO2 partial pressure in the spacecraft atmosphere.

  15. Investigating the source, transport, and isotope composition of water vapor in the planetary boundary layer

    Directory of Open Access Journals (Sweden)

    T. J. Griffis

    2016-04-01

    Full Text Available Increasing atmospheric humidity and convective precipitation over land provide evidence of intensification of the hydrologic cycle – an expected response to surface warming. The extent to which terrestrial ecosystems modulate these hydrologic factors is important to understand feedbacks in the climate system. We measured the oxygen and hydrogen isotope composition of water vapor at a very tall tower (185 m in the upper Midwest, United States, to diagnose the sources, transport, and fractionation of water vapor in the planetary boundary layer (PBL over a 3-year period (2010 to 2012. These measurements represent the first set of annual water vapor isotope observations for this region. Several simple isotope models and cross-wavelet analyses were used to assess the importance of the Rayleigh distillation process, evaporation, and PBL entrainment processes on the isotope composition of water vapor. The vapor isotope composition at this tall tower site showed a large seasonal amplitude (mean monthly δ18Ov ranged from −40.2 to −15.9 ‰ and δ2Hv ranged from −278.7 to −113.0 ‰ and followed the familiar Rayleigh distillation relation with water vapor mixing ratio when considering the entire hourly data set. However, this relation was strongly modulated by evaporation and PBL entrainment processes at timescales ranging from hours to several days. The wavelet coherence spectra indicate that the oxygen isotope ratio and the deuterium excess (dv of water vapor are sensitive to synoptic and PBL processes. According to the phase of the coherence analyses, we show that evaporation often leads changes in dv, confirming that it is a potential tracer of regional evaporation. Isotope mixing models indicate that on average about 31 % of the growing season PBL water vapor is derived from regional evaporation. However, isoforcing calculations and mixing model analyses for high PBL water vapor mixing ratio events ( >  25 mmol mol−1

  16. Investigating the source, transport, and isotope composition of water vapor in the planetary boundary layer

    Science.gov (United States)

    Griffis, Timothy J.; Wood, Jeffrey D.; Baker, John M.; Lee, Xuhui; Xiao, Ke; Chen, Zichong; Welp, Lisa R.; Schultz, Natalie M.; Gorski, Galen; Chen, Ming; Nieber, John

    2016-04-01

    Increasing atmospheric humidity and convective precipitation over land provide evidence of intensification of the hydrologic cycle - an expected response to surface warming. The extent to which terrestrial ecosystems modulate these hydrologic factors is important to understand feedbacks in the climate system. We measured the oxygen and hydrogen isotope composition of water vapor at a very tall tower (185 m) in the upper Midwest, United States, to diagnose the sources, transport, and fractionation of water vapor in the planetary boundary layer (PBL) over a 3-year period (2010 to 2012). These measurements represent the first set of annual water vapor isotope observations for this region. Several simple isotope models and cross-wavelet analyses were used to assess the importance of the Rayleigh distillation process, evaporation, and PBL entrainment processes on the isotope composition of water vapor. The vapor isotope composition at this tall tower site showed a large seasonal amplitude (mean monthly δ18Ov ranged from -40.2 to -15.9 ‰ and δ2Hv ranged from -278.7 to -113.0 ‰) and followed the familiar Rayleigh distillation relation with water vapor mixing ratio when considering the entire hourly data set. However, this relation was strongly modulated by evaporation and PBL entrainment processes at timescales ranging from hours to several days. The wavelet coherence spectra indicate that the oxygen isotope ratio and the deuterium excess (dv) of water vapor are sensitive to synoptic and PBL processes. According to the phase of the coherence analyses, we show that evaporation often leads changes in dv, confirming that it is a potential tracer of regional evaporation. Isotope mixing models indicate that on average about 31 % of the growing season PBL water vapor is derived from regional evaporation. However, isoforcing calculations and mixing model analyses for high PBL water vapor mixing ratio events ( > 25 mmol mol-1) indicate that regional evaporation can account

  17. Effect of Precipitable Water Vapor Amount on Radiative Cooling Performance

    Science.gov (United States)

    Hu, Mingke; Zhao, Bin; Ao, Xianze; Pei, Gang

    2017-05-01

    A radiative cooler based on aluminum-evaporated polyvinyl-fluoride surface was employed to investigate the effect of precipitable water vapor amount on its radiative cooling performance. A mathematic model of steady heat transfer that considers the spectral radiant distribution of the sky, the transparent cover and the collecting surface was established. The results indicate that the amount of precipitable water vapor shows a remarkable and negative effect on radiative cooling performance of the radiative cooler. Both the temperature difference between the cooler and surroundings and the net radiative cooling power decrease as the precipitable water vapor amount increases. The net radiative cooling power drops by about 41.0% as the the precipitable water vapor amount changes from 1.0 cm to 7.0 cm. Besides, the radiative cooler shows better cooling performance in winter than in summer. The net radiative cooling power in summer of Hefei is about 82.2% of that in winter.

  18. Atmospheric Hydrodeoxygenation of Biomass Fast Pyrolysis Vapor by MoO3

    DEFF Research Database (Denmark)

    Zhou, Guofeng; Jensen, Peter Arendt; Le, Duy Michael

    2016-01-01

    was not significant at temperatures below 400 °C. At 450 °C catalyst temperature and 93 vol % H2 concentration, the wood pyrolysis vapor was more active toward cracking forming gas species instead of performing the desired HDO forming hydrocarbons. The lignin pyrolysis vapor was more resistant to cracking and yielded......MoO3 has been tested as a catalyst in hydrodeoxygenation (HDO) of both model compounds (acetone and guaiacol) and real biomass pyrolysis vapors under atmospheric pressure. The pyrolysis vapor was obtained by fast pyrolysis of wood or lignin in a continuous fast pyrolysis reactor at a fixed...... temperature of 500 °C, and it subsequently passed through a downstream, close coupled, fixed bed reactor containing the MoO3 catalyst. The influences of the catalyst temperature and the concentration of H2 on the HDO of the pyrolysis vapors were investigated. The level of HDO of the biomass pyrolysis vapors...

  19. Measurement of Vapor Flow As an Important Source of Water in Dry Land Eco-Hydrology

    Science.gov (United States)

    Wang, Z.; He, Z.; Wang, Y.; Gao, Z.; Hishida, K.

    2014-12-01

    When the temperature of land surface is lower than that of air and deeper soils, water vapor gathers toward the ground surface where dew maybe formed depending on the prevailing dew point and wind speed. Some plants are able to absorb the dew and vapor flow while the soil can readily absorb both. Certain animals such as desert beetles and ants harvest the dew or fog for daily survival. Recently, it is also realized that the dew and vapor flow can be a life-saving amount of water for plant survival at the driest seasons of the year in arid and semi-arid regions. Researches are conducted to quantify the amount of near-surface vapor flow in arid and semi-arid regions in China and USA. Quantitative leaf water absorption and desorption functions were derived based on laboratory experiments. Results show that plant leaves absorb and release water at different speeds depending on species and varieties. The "ideal" native plants in the dry climates can quickly absorb water and slowly release it. This water-holding capacity of plant is characterized by the absorption and desorption functions derived for plant physiology and water balance studies. Field studies are conducted to measure the dynamic vapor flow movements from the atmosphere and the groundwater table to soil surface. Results show that dew is usually formed on soil and plant surfaces during the daily hours when the temperature gradients are inverted toward the soil surface. The amount of dew harvested using gravels on the soil surface was enough to support water melon agriculture on deserts. The vapor flow can be effectively intercepted by artificially seeded plants in semi-arid regions forming new forests. New studies are attempted to quantify the role of vapor flow for the survival of giant sequoias in the southern Sierra Nevada Mountains of California.

  20. SPARC-IGAC Symposium on Climate-Chemistry Interactions. Climate Feedback by Water Vapor in the Tropical Upper Troposphere

    Science.gov (United States)

    Dessler, A. E.; Minschwaner, K.

    2003-01-01

    The strong greenhouse forcing by atmospheric water vapor is expected to play an important role in shaping the direction of any future changes in climate. We present calculations that provide a new perspective on the sensitivity of upper tropospheric water vapor to changes in surface temperature. Equilibrium states of our atmospheric model show unambiguously that as the surface warms, changes in the vertical distribution and temperature of detraining air parcels from tropical convection lead to higher water vapor mixing ratios in the upper troposphere. However, the increase in mixing ratio is not as large as the increase in saturation mixing ratio due to warmer environmental temperatures, so that the relative humidity decreases. Our analysis suggests that models that maintain a fixed relative humidity are likely overestimating the magnitude of the water vapor feedback.

  1. In-Situ Water Vapor Probe for a Robot Arm-Mounted, Compact Water Vapor Analyzer Project

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose to test a prototype water vapor sampling end-effector in the laboratory and in the field thatwill eventually be integrated with a small, infrared...

  2. Arctic cyclone water vapor isotopes support past sea ice retreat recorded in Greenland ice.

    Science.gov (United States)

    Klein, Eric S; Cherry, J E; Young, J; Noone, D; Leffler, A J; Welker, J M

    2015-05-29

    Rapid Arctic warming is associated with important water cycle changes: sea ice loss, increasing atmospheric humidity, permafrost thaw, and water-induced ecosystem changes. Understanding these complex modern processes is critical to interpreting past hydrologic changes preserved in paleoclimate records and predicting future Arctic changes. Cyclones are a prevalent Arctic feature and water vapor isotope ratios during these events provide insights into modern hydrologic processes that help explain past changes to the Arctic water cycle. Here we present continuous measurements of water vapor isotope ratios (δ(18)O, δ(2)H, d-excess) in Arctic Alaska from a 2013 cyclone. This cyclone resulted in a sharp d-excess decrease and disproportional δ(18)O enrichment, indicative of a higher humidity open Arctic Ocean water vapor source. Past transitions to warmer climates inferred from Greenland ice core records also reveal sharp decreases in d-excess, hypothesized to represent reduced sea ice extent and an increase in oceanic moisture source to Greenland Ice Sheet precipitation. Thus, measurements of water vapor isotope ratios during an Arctic cyclone provide a critical processed-based explanation, and the first direct confirmation, of relationships previously assumed to govern water isotope ratios during sea ice retreat and increased input of northern ocean moisture into the Arctic water cycle.

  3. Recent Advances in Atmospheric Vapor-Phase Deposition of Transparent and Conductive Zinc Oxide

    NARCIS (Netherlands)

    Illiberi, A.; Poodt, P.; Roozeboom, F.

    2014-01-01

    The industrial need for high-throughput and low-cost ZnO deposition processes has triggered the development of atmospheric vapor-phase deposition techniques which can be easily applied to continuous, in-line manufacturing. While atmospheric CVD is a mature technology, new processes for the growth of

  4. Compact Raman Lidar Measurement of Liquid and Vapor Phase Water Under the Influence of Ionizing Radiation

    Directory of Open Access Journals (Sweden)

    Shiina Tatsuo

    2016-01-01

    Full Text Available A compact Raman lidar has been developed for studying phase changes of water in the atmosphere under the influence of ionization radiation. The Raman lidar is operated at the wavelength of 349 nm and backscattered Raman signals of liquid and vapor phase water are detected at 396 and 400 nm, respectively. Alpha particles emitted from 241Am of 9 MBq ionize air molecules in a scattering chamber, and the resulting ions lead to the formation of liquid water droplets. From the analysis of Raman signal intensities, it has been found that the increase in the liquid water Raman channel is approximately 3 times as much as the decrease in the vapor phase water Raman channel, which is consistent with the theoretical prediction based on the Raman cross-sections. In addition, the radius of the water droplet is estimated to be 0.2 μm.

  5. Rapid and fully automated Measurement of Water Vapor Sorption Isotherms

    DEFF Research Database (Denmark)

    Arthur, Emmanuel; Tuller, Markus; Møldrup, Per

    2014-01-01

    Eminent environmental challenges such as remediation of contaminated sites, the establishment and maintenance of nuclear waste repositories, or the design of surface landfill covers all require accurate quantification of the soil water characteristic at low water contents. Furthermore, several...... and pesticide volatilization, toxic organic vapor sorption kinetics, and soil water repellency are illustrated. Several methods to quantify hysteresis effects and to derive soil clay content and specific surface area from VSA-measured isotherms are presented. Besides above mentioned applications, potential...... essential but difficult-to-measure soil properties such as clay content and specific surface area are intimately related to water vapor sorption. Until recently, it was a major challenge to accurately measure detailed water vapor sorption isotherms within an acceptable time frame. This priority...

  6. Validation of the Harvard Lyman-α in situ water vapor instrument: Implications for the mechanisms that control stratospheric water vapor

    Science.gov (United States)

    Weinstock, E. M.; Smith, J. B.; Sayres, D. S.; Pittman, J. V.; Spackman, J. R.; Hintsa, E. J.; Hanisco, T. F.; Moyer, E. J.; St. Clair, J. M.; Sargent, M. R.; Anderson, J. G.

    2009-12-01

    Building on previously published details of the laboratory calibrations of the Harvard Lyman-α photofragment fluorescence hygrometer (HWV) on the NASA ER-2 and WB-57 aircraft, we describe here the validation process for HWV, which includes laboratory calibrations and intercomparisons with other Harvard water vapor instruments at water vapor mixing ratios from 0 to 10 ppmv, followed by in-flight intercomparisons with the same Harvard hygrometers. The observed agreement exhibited in the laboratory and during intercomparisons helps corroborate the accuracy of HWV. In light of the validated accuracy of HWV, we present and evaluate a series of intercomparisons with satellite and balloon borne water vapor instruments made from the upper troposphere to the lower stratosphere in the tropics and midlatitudes. Whether on the NASA ER-2 or WB-57 aircraft, HWV has consistently measured about 1-1.5 ppmv higher than the balloon-borne NOAA/ESRL/GMD frost point hygrometer (CMDL), the NOAA Cryogenic Frost point Hygrometer (CFH), and the Microwave Limb Sounder (MLS) on the Aura satellite in regions of the atmosphere where water vapor is <10 ppmv. Comparisons in the tropics with the Halogen Occultation Experiment (HALOE) on the Upper Atmosphere Research Satellite show large variable differences near the tropopause that converge to ˜10% above 460 K, with HWV higher. Results we show from the Aqua Validation and Intercomparison Experiment (AquaVIT) at the AIDA chamber in Karlsruhe do not reflect the observed in-flight differences. We illustrate that the interpretation of the results of comparisons between modeled and measured representations of the seasonal cycle of water entering the lower tropical stratosphere is dictated by which data set is used.

  7. Modeling Convection of Water Vapor into the Mid-latitude Summer Stratosphere

    Science.gov (United States)

    Clapp, C.; Leroy, S. S.; Anderson, J. G.

    2016-12-01

    Water vapor in the upper troposphere and lower stratosphere (UTLS) from the tropics to the poles is important both radiatively and chemically. Water vapor is the most important greenhouse gas, and increases in water vapor concentrations in the UTLS lead to cooling at these levels and induce warming at the surface [Forster and Shine, 1999; 2002; Solomon et al., 2010]. Water vapor is also integral to stratospheric chemistry. It is the dominant source of OH in the lower stratosphere [Hanisco et al., 2001], and increases in water vapor concentrations promote stratospheric ozone loss by raising the reactivity of several key heterogeneous reactions as well as by promoting the growth of reactive surface area [Anderson et al., 2012; Carslaw et al., 1995; Carslaw et al., 1997; Drdla and Muller , 2012; Kirk-Davidoff et al., 1999; Shi et al., 2001]. However, the processes that control the distribution and phase of water in this region of the atmosphere are not well understood. This is especially true at mid-latitudes where several different dynamical mechanisms are capable of influencing UTLS water vapor concentrations. The contribution by deep convective storm systems that penetrate into the lower stratosphere is the least well understood and the least well represented in global models because of the small spatial scales and short time scales over which convection occurs. To address this issue, we have begun a modeling study to investigate the convective injection of water vapor from the troposphere into the stratosphere in the mid-latitudes. Fine-scale models have been previously used to simulate convection from the troposphere to the stratosphere [e.g., Homeyer et al., 2014]. Here we employ the Advanced Research Weather and Research Forecasting model (ARW) at 3-km resolution to resolve convection over the mid-western United States during August of 2013 including a storm system observed by SEAC4RS. We assess the transport of water vapor into the stratosphere over the model

  8. Daytime Raman lidar for water vapor and ozone concentration measurements

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Duk Hyeon; Cha, Hyung Ki; Lee, Jong Min [Laboratory for QuantumOptics, Korea Atomic Energy Research Institute, Taejeon (Korea, Republic of); Veselovskii, I. [Physcis Instrumentation Center of General Physcis Institute, Moscow (Russian Federation)

    1996-11-15

    A Raman lidar system based on a quadrupled Nd : Yagi laser monitors the Raman signals from N{sub 2}, O{sub 2} and H{sub 2}O molecules. To suppress the elastic backscatter, a specially designed liquid absorption edge filter is used. The water vapor concentration is calculated from the radio of water and nitrogen Raman signals. Ozone concentration is evaluated from nitrogen and oxygen Raman returns by applying Dial technique. The obtained ozone profiles can be used for water vapor data correction.

  9. Water vapor estimation using digital terrestrial broadcasting waves

    Science.gov (United States)

    Kawamura, S.; Ohta, H.; Hanado, H.; Yamamoto, M. K.; Shiga, N.; Kido, K.; Yasuda, S.; Goto, T.; Ichikawa, R.; Amagai, J.; Imamura, K.; Fujieda, M.; Iwai, H.; Sugitani, S.; Iguchi, T.

    2017-03-01

    A method of estimating water vapor (propagation delay due to water vapor) using digital terrestrial broadcasting waves is proposed. Our target is to improve the accuracy of numerical weather forecast for severe weather phenomena such as localized heavy rainstorms in urban areas through data assimilation. In this method, we estimate water vapor near a ground surface from the propagation delay of digital terrestrial broadcasting waves. A real-time delay measurement system with a software-defined radio technique is developed and tested. The data obtained using digital terrestrial broadcasting waves show good agreement with those obtained by ground-based meteorological observation. The main features of this observation are, no need for transmitters (receiving only), applicable wherever digital terrestrial broadcasting is available and its high time resolution. This study shows a possibility to estimate water vapor using digital terrestrial broadcasting waves. In the future, we will investigate the impact of these data toward numerical weather forecast through data assimilation. Developing a system that monitors water vapor near the ground surface with time and space resolutions of 30 s and several kilometers would improve the accuracy of the numerical weather forecast of localized severe weather phenomena.

  10. Synergistic retrieval of H2O vapor in Mars' atmosphere: the path to a systematic 3D exploration of H2O vapor

    Science.gov (United States)

    Montmessin, F.; Ferron, S.

    2017-09-01

    Understanding the contemporary water cycle on Mars is a major goal in Mars' climate research. Our study has been conducted with the motivation of optimizing the scientific return of nadir observing instruments which have performed water vapor analysis at various wavelengths on Mars. First, we have evaluated the theoretical performances of jointly analyzing water vapor retrieval in both Thermal Infrared (TIR) and Short Wavelength Infrared (SWIR) ranges (i.e. less than 3 μm). We then proved, by applying our method to actual Mars Express data, that a simultaneous retrieval in the TIR and SWIR of the water vapor abundance is susceptible to provide a very strong constraint on the shape of the water vapor profile. Up to now, only a column-integrated abundance has been derived from nadir observing instruments whereas it appears now possible to derive a second information on water vapor vertical confinement, opening the path to a 3D exploration of water vapor on Mars.

  11. Remote sensing of seasonal distribution of precipitable water vapor over the oceans and inference of boundary layer structure

    Science.gov (United States)

    Prabhakara, C.

    1979-01-01

    Over the ocean satellite infrared spectral measurements in the 18 micrometer water vapor band and the 11 micrometer window region were used to derive precipitable water vapor, w, in the atmosphere and the sea surface temperature, SST. Seasonal maps of w on the oceans derived from these data reveal the dynamical influence of the large scale atmospheric circulation. With the help of a model for the vertical distribution of water vapor, the configuration of the atmospheric boundary layer over the oceans can be inferred from w when the information of SST is combined. The gross seasonal mean structure of the boundary layer inferred in this fashion reveals the broad areas of the trade wind inversion and the convectively active areas such as the intertropical convergence zones.

  12. Mapping Mars water vapor with the Very Large Array

    Science.gov (United States)

    Clancy, R. T.; Grossman, Arie W.; Muhleman, Duane O.

    1992-01-01

    This paper presents the first radio measurements of Mars atmospheric water, retrieved from interferometric spectral line observations with the NRAO VLA. Large atmospheric path lengths on the limb of Mars lead to an annulus of H2O line emission which provides a measure of the diurnal and latitudinal variability of atmospheric water on Mars. The measured line shapes of the observed H2O emission yield the first direct measurements of the vertical mixing profile of H2O in the Mars atmosphere. The observations indicate a very dry Mars atmosphere in which the globally averaged water column is approximately 3 pr micron.

  13. SPARC Data Initiative: Comparison of water vapor climatologies from international satellite limb sounders

    Science.gov (United States)

    Hegglin, M. I.; Tegtmeier, S.; Anderson, J.; Froidevaux, L.; Fuller, R.; Funke, B.; Jones, A.; Lingenfelser, G.; Lumpe, J.; Pendlebury, D.; Remsberg, E.; Rozanov, A.; Toohey, M.; Urban, J.; von Clarmann, T.; Walker, K. A.; Wang, R.; Weigel, K.

    2013-10-01

    Within the SPARC Data Initiative, the first comprehensive assessment of the quality of 13 water vapor products from 11 limb-viewing satellite instruments (LIMS, SAGE II, UARS-MLS, HALOE, POAM III, SMR, SAGE III, MIPAS, SCIAMACHY, ACE-FTS, and Aura-MLS) obtained within the time period 1978-2010 has been performed. Each instrument's water vapor profile measurements were compiled into monthly zonal mean time series on a common latitude-pressure grid. These time series serve as basis for the "climatological" validation approach used within the project. The evaluations include comparisons of monthly or annual zonal mean cross sections and seasonal cycles in the tropical and extratropical upper troposphere and lower stratosphere averaged over one or more years, comparisons of interannual variability, and a study of the time evolution of physical features in water vapor such as the tropical tape recorder and polar vortex dehydration. Our knowledge of the atmospheric mean state in water vapor is best in the lower and middle stratosphere of the tropics and midlatitudes, with a relative uncertainty of ±2-6% (as quantified by the standard deviation of the instruments' multiannual means). The uncertainty increases toward the polar regions (±10-15%), the mesosphere (±15%), and the upper troposphere/lower stratosphere below 100 hPa (±30-50%), where sampling issues add uncertainty due to large gradients and high natural variability in water vapor. The minimum found in multiannual (1998-2008) mean water vapor in the tropical lower stratosphere is 3.5 ppmv (±14%), with slightly larger uncertainties for monthly mean values. The frequently used HALOE water vapor data set shows consistently lower values than most other data sets throughout the atmosphere, with increasing deviations from the multi-instrument mean below 100 hPa in both the tropics and extratropics. The knowledge gained from these comparisons and regarding the quality of the individual data sets in different regions

  14. Using JPSS Retrievals to Implement a Multisensor, Synoptic, Layered Water Vapor Product for Forecasters

    Science.gov (United States)

    Forsythe, J. M.; Jones, A. S.; Kidder, S. Q.; Fuell, K.; LeRoy, A.; Bikos, D.; Szoke, E.

    2015-12-01

    Forecasters have been using the NOAA operational blended total precipitable water (TPW) product, developed by the Cooperative Institute for Research in the Atmosphere (CIRA), since 2009. Blended TPW has a wide variety of uses related to heavy precipitation and flooding, such as measuring the amount of moisture in an atmospheric river originating in the tropics. But blended TPW conveys no information on the vertical distribution of moisture, which is relevant to a variety of forecast concerns. Vertical profile information is particularly lacking over the oceans for landfalling storms. A blended six-satellite, four-layer, layered water vapor product demonstrated by CIRA and the NASA Short-term Prediction Research and Transition Center (SPoRT) in allows forecasters to see the vertical distribution of water vapor in near real-time. National Weather Service (NWS) forecaster feedback indicated that this new, vertically-resolved view of water vapor has a substantial impact on forecasts. This product uses NOAA investments in polar orbiting satellite sounding retrievals from passive microwave radiances, in particular, the Microwave Integrated Retrieval System (MIRS). The product currently utilizes data from the NOAA-18 and -19 spacecraft, Metop-A and -B, and the Defense Meteorological Program (DMSP) F18 spacecraft. The sounding instruments onboard the Suomi-NPP and JPSS spacecraft will be cornerstone instruments in the future evolution of this product. Applications of the product to heavy rain cases will be presented and compared to commonly used data such as radiosondes and Geostationary Operational Environmental Satellite (GOES) water vapor channel imagery. Research is currently beginning to implement advective blending, where model winds are used to move the water vapor profiles to a common time. Interactions with the NOAA Satellite Analysis Branch (SAB), National Center for Environmental Prediction (NCEP) centers including the Ocean Prediction Center (OPC) and Weather

  15. Observational Constraints on the Water Vapor Feedback Using GPS Radio Occultations

    Science.gov (United States)

    Vergados, P.; Mannucci, A. J.; Ao, C. O.; Fetzer, E. J.

    2016-12-01

    The air refractive index at L-band frequencies depends on the air's density and water vapor content. Exploiting these relationships, we derive a theoretical model to infer the specific humidity response to surface temperature variations, dq/dTs, given knowledge of how the air refractive index and temperature vary with surface temperature. We validate this model using 1.2-1.6 GHz Global Positioning System Radio Occultation (GPS RO) observations from 2007 to 2010 at 250 hPa, where the water vapor feedback on surface warming is strongest. Current research indicates that GPS RO data sets can capture the amount of water vapor in very dry and very moist air more efficiently than other observing platforms, possibly suggesting larger water vapor feedback than previously known. Inter-comparing the dq/dTs among different data sets will provide us with additional constraints on the water vapor feedback. The dq/dTs estimation from GPS RO observations shows excellent agreement with previously published results and the responses estimated using Atmospheric Infrared Sounder (AIRS) and NASA's Modern-Era Retrospective Analysis for Research and Applications (MERRA) data sets. In particular, the GPS RO-derived dq/dTs is larger by 6% than that estimated using the AIRS data set. This agrees with past evidence that AIRS may be dry-biased in the upper troposphere. Compared to the MERRA estimations, the GPS RO-derived dq/dTs is 10% smaller, also agreeing with previous results that show that MERRA may have a wet bias in the upper troposphere. Because of their high sensitivity to fractional changes in water vapor, and their inherent long-term accuracy, current and future GPS RO observations show great promise in monitoring climate feedbacks and their trends.

  16. Temporal Variations of Telluric Water Vapor Absorption at Apache Point Observatory

    Science.gov (United States)

    Li, Dan; Blake, Cullen H.; Nidever, David; Halverson, Samuel P.

    2018-01-01

    Time-variable absorption by water vapor in Earth’s atmosphere presents an important source of systematic error for a wide range of ground-based astronomical measurements, particularly at near-infrared wavelengths. We present results from the first study on the temporal and spatial variability of water vapor absorption at Apache Point Observatory (APO). We analyze ∼400,000 high-resolution, near-infrared (H-band) spectra of hot stars collected as calibration data for the APO Galactic Evolution Experiment (APOGEE) survey. We fit for the optical depths of telluric water vapor absorption features in APOGEE spectra and convert these optical depths to Precipitable Water Vapor (PWV) using contemporaneous data from a GPS-based PWV monitoring station at APO. Based on simultaneous measurements obtained over a 3° field of view, we estimate that our PWV measurement precision is ±0.11 mm. We explore the statistics of PWV variations over a range of timescales from less than an hour to days. We find that the amplitude of PWV variations within an hour is less than 1 mm for most (96.5%) APOGEE field visits. By considering APOGEE observations that are close in time but separated by large distances on the sky, we find that PWV is homogeneous across the sky at a given epoch, with 90% of measurements taken up to 70° apart within 1.5 hr having ΔPWV < 1.0 mm. Our results can be used to help simulate the impact of water vapor absorption on upcoming surveys at continental observing sites like APO, and also to help plan for simultaneous water vapor metrology that may be carried out in support of upcoming photometric and spectroscopic surveys.

  17. CONDENSATION OF WATER VAPOR IN A VERTICAL TUBE CONDENSER

    Directory of Open Access Journals (Sweden)

    Jan Havlík

    2015-10-01

    Full Text Available This paper presents an analysis of heat transfer in the process of condensation of water vapor in a vertical shell-and-tube condenser. We analyze the use of the Nusselt model for calculating the condensation heat transfer coefficient (HTC inside a vertical tube and the Kern, Bell-Delaware and Stream-flow analysis methods for calculating the shell-side HTC from tubes to cooling water. These methods are experimentally verified for a specific condenser of waste process vapor containing air. The operating conditions of the condenser may be different from the assumptions adopted in the basic Nusselt theory. Modifications to the Nusselt condensation model are theoretically analyzed.

  18. The STARTWAVE atmospheric water database

    Directory of Open Access Journals (Sweden)

    J. Morland

    2006-01-01

    Full Text Available The STARTWAVE (STudies in Atmospheric Radiative Transfer and Water Vapour Effects project aims to investigate the role which water vapour plays in the climate system, and in particular its interaction with radiation. Within this framework, an ongoing water vapour database project was set up which comprises integrated water vapour (IWV measurements made over the last ten years by ground-based microwave radiometers, Global Positioning System (GPS receivers and sun photometers located throughout Switzerland at altitudes between 330 and 3584 m. At Bern (46.95° N, 7.44° E tropospheric and stratospheric water vapour profiles are obtained on a regular basis and integrated liquid water, which is important for cloud characterisation, is also measured. Additional stratospheric water vapour profiles are obtained by an airborne microwave radiometer which observes large parts of the northern hemisphere during yearly flight campaigns. The database allows us to validate the various water vapour measurement techniques. Comparisons between IWV measured by the Payerne radiosonde with that measured at Bern by two microwave radiometers, GPS and sun photometer showed instrument biases within ±0.5 mm. The bias in GPS relative to sun photometer over the 2001 to 2004 period was –0.8 mm at Payerne (46.81° N, 6.94° E, 490 m, which lies in the Swiss plains north of the Alps, and +0.6 mm at Davos (46.81° N, 9.84° E, 1598 m, which is located within the Alps in the eastern part of Switzerland. At Locarno (46.18° N, 8.78° E, 366 m, which is located on the south side of the Alps, the bias is +1.9 mm. The sun photometer at Locarno was found to have a bias of –2.2 mm (13% of the mean annual IWV relative to the data from the closest radiosonde station at Milano. This result led to a yearly rotation of the sun photometer instruments between low and high altitude stations to improve the calibrations. In order to demonstrate the capabilites of the database for studying

  19. MODIS/Terra Aerosol, Cloud and Water Vapor Subset 5-Min L2 Swath 5km and 10km V005

    Data.gov (United States)

    National Aeronautics and Space Administration — MODATML2 contains a selection of the most useful atmosphere Level 2 aerosol, cloud and water vapor parameters at 5 and 10km spatial resolution. Native 1km cloud,...

  20. A feasibility study of a microwave water vapor measurement from a space probe along an occultation path

    Science.gov (United States)

    Longbothum, R. L.

    1975-01-01

    Stratospheric and mesospheric water vapor measurements were taken using the microwave lines at 22 GHz (22.235 GHz) and 183 GHz (183.31 GHz). The resonant cross sections for both the 22 GHz and the 183 GHz lines were used to model the optical depth of atmospheric water vapor. The range of optical depths seen by a microwave radiometer through the earth's limb was determined from radiative transfer theory. Radiometer sensitivity, derived from signal theory, was compared with calculated optical depths to determine the maximum height to which water vapor can be measured using the following methods: passive emission, passive absorption, and active absorption. It was concluded that measurements using the 22 GHz line are limited to about 50 km whereas the 183 GHz line enables measurements up to and above 100 km for water vapor mixing ratios as low as 0.1 ppm under optimum conditions.

  1. Vertical distribution of water in the atmosphere of Venus - A simple thermochemical explanation

    Science.gov (United States)

    Lewis, John S.; Grinspoon, David H.

    1990-01-01

    Several lines of evidence concerning the vertical abundance profile of water in the atmosphere of Venus lead to strikingly unusual distributions (the water vapor abundance decreases sharply in the immediate vicinity of the surface) or to serious conflicts in the profiles (different IR bands suggest water abundances that are discrepant by a factor of 2.5 to 10). These data sets can be reconciled if (1) water molecules associate with carbon dioxide and sulfur trioxide to make gaseous carbonic acid and sulfuric acid in the lower atmosphere, and (2) the discrepant 0.94-micrometer water measurements are due to gaseous sulfuric acid, requiring it to be a somewhat stronger absorber than water vapor in this wavelength region. A mean total water abundance of 50 + or - 20 parts/million and a near-surface free water vapor abundance of 10 + or - 4 parts/million are derived.

  2. Carbon and Water Vapor Fluxes of Different Ecosystems in Oklahoma

    Science.gov (United States)

    Wagle, P.; Gowda, P. H.; Northup, B. K.

    2016-12-01

    Information on exchange of energy, carbon dioxide (CO2), and water vapor (H2O) for major terrestrial ecosystems is vital to quantify carbon and water balances on a large-scale. It is also necessary to develop, test, and improve crop models and satellite-based production efficiency and evapotranspiration (ET) models, and to better understand the potential of terrestrial ecosystems to mitigate rising atmospheric CO2 concentration and climate change. A network (GRL-FLUXNET) of nine eddy flux towers has been established over a diverse range of terrestrial ecosystems, including native and improved perennial grasslands [unburned and grazed tallgrass prairie, burned and grazed tallgrass prairie, and burned Bermuda grass (Cynodon dactylon L.)], grazed and non-grazed winter wheat (Triticum aestivum L.), till and no-till winter wheat and canola (Brassica napus L.), alfalfa (Medicago sativa L.), and soybean (Glycine max L.), at the USDA-ARS, Grazinglands Research Laboratory, El Reno, OK. In this presentation, we quantify and compare net ecosystem CO2 exchange (NEE) and ET between recently burned and grazed tallgrass prairie and burned and non-grazed Bermuda grass pastures, alfalfa, and soybean. Preliminary results show monthly ensembles average NEE reached seasonal peak values of -29, -35, -25, and -20 µmol m-2 s-1 in burned tallgrass prairie pasture, burned Bermuda grass pasture, alfalfa, and soybean, respectively. Similarly, monthly ensembles average ET reached seasonal peak values of 0.22, 0.27, 0.25, 0.28 mm 30-min-1 in burned tallgrass prairie pasture, burned Bermuda grass pasture, alfalfa, and soybean, respectively. Seasonal patterns and daily magnitudes of NEE and ET and their responses to the similar climatic conditions will be further investigated.

  3. Profiles of electrostatic potential across the water-vapor, ice-vapor and ice-water interfaces

    Directory of Open Access Journals (Sweden)

    T. Bryk

    2016-02-01

    Full Text Available Ice-water, water-vapor interfaces and ice surface are studied by molecular dynamics simulations with the SPC/E model of water molecules having the purpose to estimate the profiles of electrostatic potential across the interfaces. We have proposed a methodology for calculating the profiles of electrostatic potential based on a trial particle, which showed good agreement for the case of electrostatic potential profile of the water-vapor interface of TIP4P model calculated in another way. The measured profile of electrostatic potential for the pure ice-water interface decreases towards the liquid bulk region, which is in agreement with simulations of preferential direction of motion of Li^{+} and F^{-} solute ions at the liquid side of the ice-water interface. These results are discussed in connection with the Workman-Reynolds effect.

  4. Inhibition effects of vapor phase thymol and modified atmosphere against Salmonella spp. on raw shrimp

    Science.gov (United States)

    Salmonella contamination of shrimp is a food safety concern in the U.S. and other countries. Natural antimicrobial compounds (e.g. essential oils) in vapor phase and modified atmosphere (MA) technology can inhibit the growth potential of Salmonella spp. However, each strategy has its limitations, wh...

  5. Atmospheric pressure chemical vapor deposition of ZnO: Process modeling and experiments

    NARCIS (Netherlands)

    Deelen, J. van; Illiberi, A.; Kniknie, B.; Beckers, E.H.A.; Simons, P.J.P.M.; Lankhorst, A.

    2014-01-01

    The deposition of zinc oxide has been performed by atmospheric pressure chemical vapor deposition and trends in growth rates are compared with the literature. Diethylzinc and tertiary butanol were used as the primary reactants and deposition rates above 800 nm/min were obtained. The reaction

  6. Atmospheric pressure chemical vapor deposition of ZnO: Process modeling and experiments

    NARCIS (Netherlands)

    Deelen, J. van; Illiberi, A.; Kniknie, B.; Beckers, E.H.A.; Simons, P.J.P.M.; Lankhorst, A.

    2013-01-01

    The deposition of zinc oxide has been performed by atmospheric pressure chemical vapor deposition and trends in growth rates are compared with the literature. Diethylzinc and tertiary butanol were used as the primary reactants and deposition rates above 800 nm/minwere obtained. The reaction

  7. Venus cloud structure and water vapor abundance from Mariner 10 observations

    Science.gov (United States)

    Taylor, F. W.

    1976-01-01

    Observations of the Venus atmosphere with the infrared radiometer on Mariner 10 have been analyzed by Taylor (1975) in terms of the vertical distribution of opacity at wavelengths near 11 microns and 45 microns in the thermal infrared. In this paper, we discuss models of the Venus atmosphere which are consistent with the inferred opacity structure. Either a two-layer cloud structure, or a single cloud deck overlaid by a layer containing approximately 40 precipitable microns of water vapor, would have the required limb-darkening characteristics at the wavelengths of observation.

  8. Adsorption of N-hexane, methanol and water vapor and binary mixtures of N-hexane/water vapor on super activated carbon nanoparticles

    Science.gov (United States)

    Prado, Jesus Antonio

    Recent times have seen a large rise in the utilization of engineered nanomaterials (ENMs) within a wide variety of industries due to their unique properties. Consequently, the fabrication, application and disposal of ENMs will inevitably lead to their release to the environment. Once ENMs are in the environment, they may undergo atmospheric transformations, such the sorption of hazardous air pollutants (HAPs) or water vapor. These transformed ENMs may then affect the general public through inhalation -- or other pathways of exposure -- and those employed by the ever-growing nanotechnology sector are of particular vulnerability. As a result, it is important to evaluate the adsorption characteristics of a common carbon-based ENM under the presence of HAPs or water vapor which may adsorb onto them. This study investigated the unary and binary gas-phase adsorption of n-hexane, methanol and water vapor on super activated carbon nanoparticles (SACNPs) with a bench-scale adsorption system. Removal efficiencies, breakthrough tests, throughput ratios, adsorption capacities and kinetics modeling were completed to assess the adsorption behavior of the SACNPs.

  9. Water vapor pressure versus environmental lapse rate near the tropopause

    Science.gov (United States)

    Ferreira, Antonio; Castanheira, Jose; Gimeno, Luis

    2010-05-01

    The relationship between water vapor pressure and temperature lapse rate in the vicinity of the tropopause was investigated using in situ observations. The water vapor partial pressures and the lapse rates within a vertical distance of ±1.5 km around the first thermal tropopause were calculated from the vertical soundings conducted by the NOAA/CMDL at several locations in the last few decades (GMD Data Archive). A positive non-linear relationship between the two quantities was found to hold across the studied tropopause region at mid-latitudes and polar latitudes. A similar analysis was performed on the 300 and 250 hPa pressure levels (which often intercept the tropopause region), by collecting temperature and humidity observations within 1979-2008 from the Integrated Global Radiosonde Archive (IGRA). A relationship having almost the same shape was detected for statically stable lapse rates at all latitude zones. Given the relevance of water vapor in the radiative transfer in the upper troposphere, the results are an indication of a local influence of water vapor on the thermal structure of the transition layer between the troposphere and stratosphere

  10. Continuous monitoring of summer surface water vapor isotopic composition above the Greenland Ice Sheet

    Directory of Open Access Journals (Sweden)

    H. C. Steen-Larsen

    2013-05-01

    Full Text Available We present here surface water vapor isotopic measurements conducted from June to August 2010 at the NEEM (North Greenland Eemian Drilling Project camp, NW Greenland (77.45° N, 51.05° W, 2484 m a.s.l.. Measurements were conducted at 9 different heights from 0.1 m to 13.5 m above the snow surface using two different types of cavity-enhanced near-infrared absorption spectroscopy analyzers. For each instrument specific protocols were developed for calibration and drift corrections. The inter-comparison of corrected results from different instruments reveals excellent reproducibility, stability, and precision with a standard deviations of ~ 0.23‰ for δ18O and ~ 1.4‰ for δD. Diurnal and intraseasonal variations show strong relationships between changes in local surface humidity and water vapor isotopic composition, and with local and synoptic weather conditions. This variability probably results from the interplay between local moisture fluxes, linked with firn–air exchanges, boundary layer dynamics, and large-scale moisture advection. Particularly remarkable are several episodes characterized by high (> 40‰ surface water vapor deuterium excess. Air mass back-trajectory calculations from atmospheric analyses and water tagging in the LMDZiso (Laboratory of Meteorology Dynamics Zoom-isotopic atmospheric model reveal that these events are associated with predominant Arctic air mass origin. The analysis suggests that high deuterium excess levels are a result of strong kinetic fractionation during evaporation at the sea-ice margin.

  11. Inter-comparison of three commercial instruments for water vapor isotope measurement

    Science.gov (United States)

    Wen, X.; Sun, X.; Li, S.; Lee, X.

    2010-12-01

    The δ18O and δD of atmospheric water vapor provide rich information on the hydrological cycle and gaseous exchange processes between the terrestrial vegetation and the atmosphere. In the past, the majority of water vapor isotope studies have relied on discrete sampling using cold-trap/mass spectrometry methods. Recent development of isotope ratio infrared spectroscopy (IRIS) has made it possible to make in-situ, continuous observations of the δ18O and δD of atmospheric water vapor. In this paper, we report the results of an inter-comparison experiment using three commercial IRIS analyzers. These analyzers were developed on the basis of tunable diode laser absorption spectroscopy (model TGA100A, Campbell Scientific Inc., Logan, UT), off-axis integrated cavity output spectroscopy (model DLT-100, Los Gatos Research, Mountain View, CA) and wavelength-scanned cavity ring-down spectroscopy (models L1115-i and L1102-i, Picarro Inc., Sunnyvale, CA). Each analyzer was calibrated, at factory recommended frequencies, with its own calibration device traceable to the same working standard. The experiment consisted of two parts each lasting 2 weeks. First, the δ18O and δD of ambient water vapor from a common intake were measured simultaneously with these analyzers. The data reported for hourly intervals were analyzed to reveal how well these analyzers track natural variability in ambient conditions. Second, a home-made bubbler combined with dry air was used for performance evaluation under controlled conditions. The bubbler produced a moisture stream that followed the Rayleigh prediction, and with appropriate mixing with dry air provided a sufficient range of humidity at preset levels of mixing ratio (30,000, 20,000, 10,000, 5,000 ppm). Analysis of the experimental data is underway to (1) evaluate the relative precision and accuracy among these analyzers, (2) compare the measured isotopic ratios against the Rayleigh prediction, and (3) identify appropriate calibration

  12. Explosion characteristics of flammable organic vapors in nitrous oxide atmosphere.

    Science.gov (United States)

    Koshiba, Yusuke; Takigawa, Tomihisa; Matsuoka, Yusaku; Ohtani, Hideo

    2010-11-15

    Despite unexpected explosion accidents caused by nitrous oxide have occurred, few systematic studies have been reported on explosion characteristics of flammable gases in nitrous oxide atmosphere compared to those in air or oxygen. The objective of this paper is to characterize explosion properties of mixtures of n-pentane, diethyl ether, diethylamine, or n-butyraldehyde with nitrous oxide and nitrogen using three parameters: explosion limit, peak explosion pressure, and time to the peak explosion pressure. Then, similar mixtures of n-pentane, diethyl ether, diethylamine, or n-butyraldehyde with oxygen and nitrogen were prepared to compare their explosion characteristics with the mixtures containing nitrous oxide. The explosion experiments were performed in a cylindrical vessel at atmospheric pressure and room temperature. The measurements showed that explosion ranges of the mixtures containing nitrous oxide were narrow compared to those of the mixtures containing oxygen. On the other hand, the maximum explosion pressures of the mixtures containing nitrous oxide were higher than those of the mixtures containing oxygen. Moreover, our experiments revealed that these mixtures differed in equivalence ratios at which the maximum explosion pressures were observed: the pressures of the mixtures containing nitrous oxide were observed at stoichiometry; in contrast, those of the mixtures containing oxygen were found at fuel-rich area. Chemical equilibrium calculations confirmed these behaviors. Copyright © 2010 Elsevier B.V. All rights reserved.

  13. The interaction of the theophylline metastable phase with water vapor

    Science.gov (United States)

    Matvienko, A. A.; Boldyrev, V. V.; Sidel'Nikov, A. A.; Chizhik, S. A.

    2008-07-01

    The conditions of hydration of the stable and metastable theophylline phases were determined. Two-phase metastable phase/monohydrate and stable phase/monohydrate equilibrium pressures were measured at 25, 30, and 35°C. The metastable phase began to react with water vapor at lower relative humidities than the stable phase. Processes that occurred with the metastable and stable theophylline phases over various water pressure ranges were considered. The metastable phase exhibited an unusual behavior at 25°C and relative humidity 47%. At constant water vapor pressure and temperature, theophylline was initially hydrated and then lost water and again became anhydrous. Two consecutive processes occurred in the system, the formation of theophylline monohydrate from the metastable phase and its decomposition to the stable phase. The ratio between the rates of these processes determined the content of the monohydrate at the given time moment.

  14. Proton magnetic relaxation in aromatic polyamides during water vapor sorption

    Science.gov (United States)

    Smotrina, T. V.; Chulkova, Yu. S.; Karasev, D. V.; Lebedeva, N. P.; Perepelkin, K. E.; Grebennikov, S. F.

    2009-07-01

    The state of the components in the aromatic polyamide-water system was studied by NMR and sorption. A comparative analysis of spin-lattice and spin-spin relaxation in aromatic para-polyamide ( para-aramid) technical fibers Rusar, Kevlar, and Technora was performed depending on the sorption value. The NMR results correlated with the supramolecular structure of polymers and quasi-chemical equation parameters for water vapor sorption.

  15. Vaporization of fault water during seismic slip

    NARCIS (Netherlands)

    Chen, Jianye; Niemeijer, André R.; Fokker, Peter A.

    Laboratory and numerical studies, as well as field observations, indicate that phase transitions of pore water might be an important process in large earthquakes. We present a model of the thermo-hydro-chemo-mechanical processes, including a two-phase mixture model to incorporate the phase

  16. Q Conversion Factor Models for Estimating Precipitable Water Vapor for Turkey

    Science.gov (United States)

    Deniz, Ilke; Mekik, Cetin; Gurbuz, Gokhan

    2015-04-01

    precipitable water vapor is the conversion factor Q which is shown in Emardson and Derks' studies and also Jade and Vijayan's. Developing a regional model using either Tm-Ts equation or the conversion factor Q will provide a basis for GNSS Meteorology in Turkey which depends on the analysis of the radiosonde profile data. For this purpose, the radiosonde profiles from Istanbul, Ankara, Diyarbaki r, Samsun, Erzurum, Izmir, Isparta and Adana stations are analyzed with the radiosonde analysis algorithm in the context of the 'The Estimation of Atmospheric Water Vapour with GPS' Project which is funded by the Scientific and Technological Research Council of Turkey (TUBITAK). The Project is also in the COST Action ES1206: Advanced Global Navigation Satellite Systems tropospheric products for monitoring severe weather events and climate (GNSS4SWEC). In this study, regional models using the conversion factor Q are used for the determination of precipitable water vapor, and applied to the GNSS derived wet tropospheric zenith delays. Henceforth, the estimated precipitable water vapor and the precipitable water vapor obtained from the radiosonde station are compared. The average of the differences between RS and models for Istanbul and Ankara stations are obtained as 2.0±1.6 mm, 1.6±1.6 mm, respectively.

  17. Modeling and measurement of boiling point elevation during water vaporization from aqueous urea for SCR applications

    Energy Technology Data Exchange (ETDEWEB)

    Dan, Ho Jin; Lee, Joon Sik [Seoul National University, Seoul (Korea, Republic of)

    2016-03-15

    Understanding of water vaporization is the first step to anticipate the conversion process of urea into ammonia in the exhaust stream. As aqueous urea is a mixture and the urea in the mixture acts as a non-volatile solute, its colligative properties should be considered during water vaporization. The elevation of boiling point for urea water solution is measured with respect to urea mole fraction. With the boiling-point elevation relation, a model for water vaporization is proposed underlining the correction of the heat of vaporization of water in the urea water mixture due to the enthalpy of urea dissolution in water. The model is verified by the experiments of water vaporization as well. Finally, the water vaporization model is applied to the water vaporization of aqueous urea droplets. It is shown that urea decomposition can begin before water evaporation finishes due to the boiling-point elevation.

  18. Forward modeling and retrieval of water vapor from the Global Ozone Monitoring Experiment: Treatment of narrowband absorption spectra

    NARCIS (Netherlands)

    Lang, R.; Maurellis, A.N.; van der Zande, W.J.; Aben, I.; Landgraf, J.; Ubachs, W.M.G.

    2002-01-01

    [1] We present the algorithm and results for a new fast forward modeling technique applied to the retrieval of atmospheric water vapor from satellite measurements using a weak ro-vibrational overtone band in the visible. The algorithm uses an Optical Absorption Coefficient Spectroscopy (OACS) method

  19. Historic and projected changes in vapor pressure deficit suggest a continental-scale drying of the United States atmosphere

    Science.gov (United States)

    Ficklin, Darren L.; Novick, Kimberly A.

    2017-02-01

    Via air temperature increases and relative humidity changes, climate change will modify vapor pressure deficit (VPD), which is an important determinant of water vapor and CO2 exchange between the land surface and atmosphere. VPD is the difference between the water vapor the air can hold at saturation (es) and the actual amount of water vapor (ea). Here we assess changes in VPD, es, and ea in the United States (U.S.) for the recent past (1979-2013) and the future (2065-2099) using gridded, observed climate data and output from general circulation models. Historically, VPD has increased for all seasons, driven by increases in es and declines in ea. The spring, summer, and fall seasons exhibited the largest areal extent of significant increases in VPD, which was largely concentrated in the western and southern portions of the U.S. The changes in VPD stemmed from recent air temperature increases and relative humidity decreases. Projections indicate similar, amplified patterns into the future. For the summer, the general circulation model ensemble median showed a 51% projected increase (quartile range of 39 and 64%) in summer VPD for the U.S., reflecting temperature-driven increases in es but decreases or minimal changes in relative humidity that promotes negligible changes in ea. Using a simple model for plant hydraulic functioning, we also show that in the absence of stomatal acclimation, future changes in VPD can reduce stomatal conductance by 9-51%, which is a magnitude comparable to the expected decline in stomatal conductance from rising CO2.

  20. Modeling coupled interactions of carbon, water, and ozone exchange between terrestrial ecosystems and the atmosphere

    Science.gov (United States)

    Ned Nikolova; Karl F. Zeller

    2003-01-01

    A new biophysical model (FORFLUX) is presented to study the simultaneous exchange of ozone, carbon dioxide, and water vapor between terrestrial ecosystems and the atmosphere. The model mechanistically couples all major processes controlling ecosystem flows trace gases and water implementing recent concepts in plant eco-physiology, micrometeorology, and soil hydrology....

  1. Surface potential of the water liquid-vapor interface

    Science.gov (United States)

    Wilson, Michael A.; Pohorille, Andrew; Pratt, Lawrence R.

    1988-01-01

    An analysis of an extended molecular dynamics calculation of the surface potential (SP) of the water liquid-vapor interface is presented. The SP predicted by the TIP4P model is -(130 + or - 50) mV. This value is of reasonable magnitude but of opposite sign to the expectations based on laboratory experiments. The electrostatic potential shows a nonmonotonic variation with depth into the liquid.

  2. Tagging Water Sources in Atmospheric Models

    Science.gov (United States)

    Bosilovich, M.

    2003-01-01

    Tagging of water sources in atmospheric models allows for quantitative diagnostics of how water is transported from its source region to its sink region. In this presentation, we review how this methodology is applied to global atmospheric models. We will present several applications of the methodology. In one example, the regional sources of water for the North American Monsoon system are evaluated by tagging the surface evaporation. In another example, the tagged water is used to quantify the global water cycling rate and residence time. We will also discuss the need for more research and the importance of these diagnostics in water cycle studies.

  3. Surface tension of water in the presence of perfluorocarbon vapors.

    Science.gov (United States)

    Chernyshev, Vasiliy S; Skliar, Mikhail

    2014-03-28

    Fluorocarbons are highly hydrophobic, biocompatible compounds with a variety of medical applications. Despite significant interest, the study of interfacial properties of fluorocarbons in aqueous systems has received limited attention. In this study, we investigate the influence of perfluoropentane and perfluorohexane vapors on the surface tension of water at room temperature. The results show a substantial decrease in the surface tension of water in the presence of perfluorocarbon vapors. In the investigated range of partial pressures up to the saturation value, a linear correlation between the surface tension and the partial pressure was found. This suggests that an adsorbed perfluorocarbon layer is formed on the surface of water. For comparison, the effect of the perfluorocarbon vapor on the surface tension of methanol was also investigated and a similar dependence was observed. Our results indicate that the stability and dynamic transitions of fluorocarbon colloids, which may be dispersed under physiological conditions as microdroplets, bubbles, or their combination, are likely affected by the composition of liquid and gas phases.

  4. Adsorption characteristics of water vapor on ferroaluminophosphate for desalination cycle

    KAUST Repository

    Kim, Youngdeuk

    2014-07-01

    The adsorption characteristics of microporous ferroaluminophosphate adsorbent (FAM-Z01, Mitsubishi Plastics) are evaluated for possible application in adsorption desalination and cooling (AD) cycles. A particular interest is its water vapor uptake behavior at assorted adsorption temperatures and pressures whilst comparing them to the commercial silica gels of AD plants. The surface characteristics are first carried out using N2 gas adsorption followed by the water vapor uptake analysis for temperature ranging from 20°C to 80°C. We propose a hybrid isotherm model, composing of the Henry and the Sips isotherms, which can be integrated to satisfactorily fit the experimental data of water adsorption on the FAM-Z01. The hybrid model is selected to fit the unusual isotherm shapes, that is, a low adsorption in the initial section and followed by a rapid vapor uptake leading to a likely micropore volume filling by hydrogen bonding and cooperative interaction in micropores. It is shown that the equilibrium adsorption capacity of FAM-Z01 can be up to 5 folds higher than that of conventional silica gels. Owing to the quantum increase in the adsorbate uptake, the FAM-Z01 has the potential to significantly reduce the footprint of an existing AD plant for the same output capacity. © 2014 Elsevier B.V.

  5. STRATOSPHERIC TEMPERATURES AND WATER LOSS FROM MOIST GREENHOUSE ATMOSPHERES OF EARTH-LIKE PLANETS

    Energy Technology Data Exchange (ETDEWEB)

    Kasting, James F.; Kopparapu, Ravi K. [Department of Geosciences, The Pennsylvania State University, State College, PA 16801 (United States); Chen, Howard, E-mail: jfk4@psu.edu, E-mail: hwchen@bu.edu [Department of Astronomy, Boston University, 725 Commonwealth Ave., Boston, MA 02215 (United States)

    2015-11-01

    A radiative-convective climate model is used to calculate stratospheric temperatures and water vapor concentrations for ozone-free atmospheres warmer than that of modern Earth. Cold, dry stratospheres are predicted at low surface temperatures, in agreement with recent 3D calculations. However, at surface temperatures above 350 K, the stratosphere warms and water vapor becomes a major upper atmospheric constituent, allowing water to be lost by photodissociation and hydrogen escape. Hence, a moist greenhouse explanation for loss of water from Venus, or some exoplanet receiving a comparable amount of stellar radiation, remains a viable hypothesis. Temperatures in the upper parts of such atmospheres are well below those estimated for a gray atmosphere, and this factor should be taken into account when performing inverse climate calculations to determine habitable zone boundaries using 1D models.

  6. Fuel for cyclones: The water vapor budget of a hurricane as dependent on its movement

    Science.gov (United States)

    Makarieva, Anastassia M.; Gorshkov, Victor G.; Nefiodov, Andrei V.; Chikunov, Alexander V.; Sheil, Douglas; Nobre, Antonio Donato; Li, Bai-Lian

    2017-09-01

    Despite the dangers associated with tropical cyclones and their rainfall, the origin of the moisture in these storms, which include destructive hurricanes and typhoons, remains surprisingly uncertain. Existing studies have focused on the region 40-400 km from a cyclone's center. It is known that the rainfall within this area cannot be explained by local processes alone but requires imported moisture. Nonetheless, the dynamics of this imported moisture appears unknown. Here, considering a region up to three thousand kilometers from cyclone center, we analyze precipitation, atmospheric moisture and movement velocities for severe tropical cyclones - North Atlantic hurricanes. Our findings indicate that even over such large areas a hurricane's rainfall cannot be accounted for by concurrent evaporation. We propose instead that a hurricane consumes pre-existing atmospheric water vapor as it moves. The propagation velocity of the cyclone, i.e. the difference between its movement velocity and the mean velocity of the surrounding air (steering flow), determines the water vapor budget. Water vapor available to the hurricane through its movement makes the hurricane self-sufficient at about 700 km from the hurricane center obviating the need to concentrate moisture from greater distances. Such hurricanes leave a dry wake, whereby rainfall is suppressed by up to 40% compared to the local long-term mean. The inner radius of this dry footprint approximately coincides with the hurricane's radius of water self-sufficiency. We discuss how Carnot efficiency considerations do not constrain the power of such open systems. Our findings emphasize the incompletely understood role and importance of atmospheric moisture stocks and dynamics in the behavior of severe tropical cyclones.

  7. Effect of Water Vapor, Temperature, and Rapid Annealing on Formamidinium Lead Triiodide Perovskite Crystallization

    Energy Technology Data Exchange (ETDEWEB)

    Aguiar, Jeffery A.; Wozny, Sarah; Alkurd, Nooraldeen R.; Yang, Mengjin; Kovarik, Libor; Holesinger, Terry G.; Al-Jassim, Mowafak; Zhu, Kai; Zhou, Weilie; Berry, Joseph J.

    2016-07-08

    Perovskite-based solar cells are one of the emerging candidates for radically lower cost photovoltaics. Herein, we report on the synthesis and crystallization of organic-inorganic formamidinium lead triiodide perovskite films under controlled atmospheric and environmental conditions. Using in situ (scanning) transmission electron microscopy, we make observations of the crystallization process of these materials in nitrogen and oxygen gas with and without the presence of water vapor. Complementary planar samples were also fabricated in the presence of water vapor and characterized by in situ X-ray diffraction. Direct observations of the material structure and final morphology indicate that the exposure to water vapor results in a porous film that is metastable, regardless of the presence of argon, nitrogen, or oxygen. However, the optimal crystallization temperature of 175 degrees C is unperturbed across conditions. Rapid modulation about the annealing temperature of 175 degrees C in +/-25 degrees C steps (150-200 degrees C) promotes crystallization and significantly improves the film morphology by overcoming the presence of impregnated water trapped in the material. Following this processing protocol, we demonstrate substantial growth to micron-size grains via observation inside of an environmentally controlled transmission electron microscope. Adapting this insight from our in situ microscopy, we are able to provide an informed materials protocol to control the structure and morphology of these organic-inorganic semiconductors, which is readily applicable to benchtop device growth strategies.

  8. Effect of Water Vapor, Temperature, and Rapid Annealing on Formamidinium Lead Triiodide Perovskite Crystallization

    Energy Technology Data Exchange (ETDEWEB)

    Aguiar, Jeffery A.; Wozny, Sarah; Alkurd, Nooraldeen R.; Yang, Mengjin; Kovarik, Libor; Holesinger, Terry; Al-Jassim, Mowafak M.; Zhu, Kai; Zhou, Weilie; Berry, J. J.

    2016-07-08

    Perovskite-based solar cells are one of the emerging candidates for radically lower cost photovoltaics. Herein, we report on the synthesis and crystallization of organic-inorganic formamidinium lead triiodide perovskite films under controlled atmospheric and environmental conditions. Using in situ (scanning) transmission electron microscopy, we make observations of the crystallization process of these materials in nitrogen and oxygen gas with and without the presence of water vapor. Complementary planar samples were also fabricated in the presence of water vapor and characterized by in situ X-ray diffraction. Direct observations of the material structure and final morphology indicate that the exposure to water vapor results in a porous film that is metastable, regardless of the presence of argon, nitrogen, or oxygen. However, the optimal crystallization temperature of 175 °C is unperturbed across conditions. Rapid modulation about the annealing temperature of 175 °C in ±25 °C steps (150-200 °C) promotes crystallization and significantly improves the film morphology by overcoming the presence of impregnated water trapped in the material. Following this processing protocol, we demonstrate substantial growth to micron-size grains via observation inside of an environmentally controlled transmission electron microscope. Adapting this insight from our in situ microscopy, we are able to provide an informed materials protocol to control the structure and morphology of these organic-inorganic semiconductors, which is readily applicable to benchtop device growth strategies.

  9. Microwave and Millimeter-Wave Radiometric Studies of Temperature, Water Vapor and Clouds

    Energy Technology Data Exchange (ETDEWEB)

    Westwater, Edgeworth

    2011-05-06

    The importance of accurate measurements of column amounts of water vapor and cloud liquid has been well documented by scientists within the Atmospheric Radiation Measurement (ARM) Program. At the North Slope of Alaska (NSA), both microwave radiometers (MWR) and the MWRProfiler (MWRP), been used operationally by ARM for passive retrievals of the quantities: Precipitable Water Vapor (PWV) and Liquid Water Path (LWP). However, it has been convincingly shown that these instruments are inadequate to measure low amounts of PWV and LWP. In the case of water vapor, this is especially important during the Arctic winter, when PWV is frequently less than 2 mm. For low amounts of LWP (< 50 g/m{sup 2}), the MWR and MWRP retrievals have an accuracy that is also not acceptable. To address some of these needs, in March-April 2004, NOAA and ARM conducted the NSA Arctic Winter Radiometric Experiment - Water Vapor Intensive Operational Period at the ARM NSA/Adjacent Arctic Ocean (NSA/AAO) site. After this experiment, the radiometer group at NOAA moved to the Center for Environmental Technology (CET) of the Department of Electrical and Computer Engineering of the University of Colorado at Boulder. During this 2004 experiment, a total of 220 radiosondes were launched, and radiometric data from 22.235 to 380 GHz were obtained. Primary instruments included the ARM MWR and MWRP, a Global Positioning System (GPS), as well as the CET Ground-based Scanning Radiometer (GSR). We have analyzed data from these instruments to answer several questions of importance to ARM, including: (a) techniques for improved water vapor measurements; (b) improved calibration techniques during cloudy conditions; (c) the spectral response of radiometers to a variety of conditions: clear, liquid, ice, and mixed phase clouds; and (d) forward modeling of microwave and millimeter wave brightness temperatures from 22 to 380 GHz. Many of these results have been published in the open literature. During the third year of

  10. Operation of a breadboard liquid-sorbent/membrane-contactor system for removing carbon dioxide and water vapor from air

    Science.gov (United States)

    Mccray, Scott B.; Ray, Rod; Newbold, David D.; Millard, Douglas L.; Friesen, Dwayne T.; Foerg, Sandra

    1992-01-01

    Processes to remove and recover carbon dioxide (CO2) and water vapor from air are essential for successful long-duration space missions. This paper presents results of a developmental program focused on the use of a liquid-sorbent/membrane-contactor (LSMC) system for removal of CO2 and water vapor from air. In this system, air from the spacecraft cabin atmosphere is circulated through one side of a hollow-fiber membrane contactor. On the other side of the membrane contactor is flowed a liquid sorbent, which absorbs the CO2 and water vapor from the feed air. The liquid sorbent is then heated to desorb the CO2 and water vapor. The CO2 is subsequently removed from the system as a concentrated gas stream, whereas the water vapor is condensed, producing a water stream. A breadboard system based on this technology was designed and constructed. Tests showed that the LSMC breadboard system can produce a CO2 stream and a liquid-water stream. Details are presented on the operation of the system, as well as the effects on performance of variations in feed conditions.

  11. Water vapor stable isotope observations from tropical Australia

    KAUST Repository

    Parkes, Stephen

    2015-04-01

    The response of the tropical hydrological cycle to anthropogenically induced changes in radiative forcing is one of the largest discrepancies between climate models. Paleoclimate archives of the stable isotopic composition of precipitation in the tropics indicate a relationship with precipitation amount that could be exploited to study past hydroclimate and improve our knowledge of how this region responds to changes in climate forcing. Recently modelling studies of convective parameterizations fitted with water isotopes and remote sensing of water vapor isotopes in the tropics have illustrated uncertainty in the assumed relationship with rainfall amount. Therefore there is a need to collect water isotope data in the tropics that can be used to evaluate these models and help identify the relationships between the isotopic composition of meteoric waters and rainfall intensity. However, data in this region is almost non-existent. Here we present in-situ water vapor isotopic measurements and the HDO retrievals from the co-located Total Column Carbon Observing Network (TCCON) site at Darwin in Tropical Australia. The Darwin site is interestingly placed within the tropical western pacific region and is impacted upon by a clear monsoonal climate, and key climate cycles including ENSO and Madden Julian Oscillations. The analysis of the data illustrated relationships between water vapor isotopes and humidity which demonstrated the role of precipitation processes in the wet season and air mass mixing during the dry season. Further the wet season observations show complex relationships between humidity and isotopes. A simple Rayleigh distillation model was not obeyed, instead the importance of rainfall re-evaporation in generating the highly depleted signatures was demonstrated. These data potentially provide a useful tool for evaluating model parameterizations in monsoonal regions as they demonstrate relationships with precipitation processes that cannot be observed with

  12. Estimation water vapor content using the mixing ratio method and validated with the ANFIS PWV model

    Science.gov (United States)

    Suparta, W.; Alhasa, K. M.; Singh, M. S. J.

    2017-05-01

    This study reported the comparison between water vapor content, the surface meteorological data (pressure, temperature, and relative humidity), and precipitable water vapor (PWV) produced by PWV from adaptive neuro fuzzy inference system (ANFIS) for areas in the Universiti Kebangsaan Malaysia Bangi (UKMB) station. The water vapor content value was estimated with mixing ratio method and the surface meteorological data as the parameter inputs. The accuracy of water vapor content was validated with PWV from ANFIS PWV model for the period of 20-23 December 2016. The result showed that the water vapor content has a similar trend with the PWV which produced by ANFIS PWV model (r = 0.975 at the 99% confidence level). This indicates that the water vapor content that obtained with mixing ratio agreed very well with the ANFIS PWV model. In addition, this study also found, the pattern of water vapor content and PWV have more influenced by the relative humidity.

  13. Stable isotopic composition of water vapor in the tropics

    Science.gov (United States)

    Lawrence, James Robert; Gedzelman, Stanley David; Dexheimer, Darielle; Cho, Hye-Khung; Carrie, Gordon D.; Gasparini, Robert; Anderson, Casey R.; Bowman, Kenneth P.; Biggerstaff, Mike I.

    2004-03-01

    Water vapor samples collected during tropical field experiments at Puerto Escondido, Mexico, near Kwajalein (KWAJEX), and near Key West, Florida (CAMEX 4), were analyzed for their stable isotope contents, 1H218O:1H216O and 2H1H16O:1H216O. Highest δ18O values approached isotopic equilibrium with seawater during quiescent weather or in regions of isolated or disorganized convection. Lowest δ18O values occurred in or downwind from regions of organized mesoscale weather disturbances and ranged as low as 15‰ below isotopic equilibrium with seawater. The mean δ18O value of vapor over the sea surface therefore decreases as storm activity and organization increases.

  14. Airborne Lidar Observations of Water Vapor Variability in Tropical Shallow Convective Environment

    Science.gov (United States)

    Kiemle, Christoph; Groß, Silke; Wirth, Martin; Bugliaro, Luca

    2017-10-01

    An airborne downward-pointing water vapor lidar provides two-dimensional, simultaneous curtains of atmospheric backscatter and humidity along the flight track with high accuracy and spatial resolution. In order to improve the knowledge on the coupling between clouds, circulation and climate in the trade wind region, the DLR (Deutsches Zentrum für Luft- und Raumfahrt) water vapor lidar was operated on board the German research aircraft HALO during the NARVAL (Next Generation Aircraft Remote Sensing for Validation Studies) field experiment in December 2013. Out of the wealth of about 30 flight hours or 25,000 km of data over the Tropical Atlantic Ocean east of Barbados, three 2-h-long, representative segments from different flights were selected. Analyses of Meteosat Second Generation images and dropsondes complement this case study. All observations indicate a high heterogeneity of the humidity in the lowest 4 km of the tropical troposphere, as well as of the depth of the cloud (1-2 km thick) and sub-cloud layer ( 1 km thick). At the winter trade inversion with its strong humidity jump of up to 9 g/kg in water vapor mixing ratio, the mixing ratio variance can attain 9 (g/kg)2, while below it typically ranges between 1 and 3 (g/kg)2. Layer depths and partial water vapor columns within the layers vary by up to a factor of 2. This affects the total tropospheric water vapor column, amounting on average to 28 kg/m2, by up to 10 kg/m2 or 36%. The dominant scale of the variability is given by the extent of regions with higher-than-average humidity and lies between 300 and 600 km. The variability mainly stems from the alternation between dry regions and moisture lifted by convection. Occasionally, up to 100-km large dry regions are observed. In between, convection pushes the trade inversion upward, sharpening the vertical moisture gradient that is colocated with the trade inversion. In most of the water vapor profiles, this gradient is stronger than the one located at the

  15. Airborne Lidar Observations of Water Vapor Variability in the Northern Atlantic Trades

    Science.gov (United States)

    Kiemle, Christoph; Groß, Silke; Wirth, Martin; Bugliaro, Luca

    2017-04-01

    During the NARVAL (Next Generation Aircraft Remote Sensing for Validation Studies) field experiments in December 2013 and August 2016 the DLR lidar WALES (Water vapor Lidar Experiment in Space) was operated on board the German research aircraft HALO. The lidar simultaneously provided two-dimensional curtains of atmospheric backscatter and humidity along the flight track with high accuracy and spatial resolution, in order to help improve our knowledge on the coupling between water vapor, clouds, and circulation in the trades. The variability of water vapor, ubiquitous in our measurements, poses challenges to climate models because it acts on the small-scale low-cloud cover. Aloft, the very dry free troposphere in the subsiding branch of the Hadley cell acts as an open window in a greenhouse, efficiently cooling the lower troposphere. Secondary circulations between radiatively heated and cooled regions are supposed to occur, adding complexity to the situation. After recently having identified them to be mainly responsible for the uncertainty in global climate sensitivity, such interactions between shallow convection, circulation and radiation are at the heart of present scientific debate, endorsed by the WCRP (World Climate Research Programme) "Grand Challenge on Clouds, Circulation and Climate Sensitivity". Out of the wealth of about 30 winter and 60 summer flight hours totaling 75000 km of data over the Tropical Atlantic Ocean east of Barbados, several representative lidar segments from different flights are presented, together with Meteosat Second Generation (MSG) images and dropsonde profiles. All observations indicate high heterogeneity of the humidity in the lowest 5 km, as well as high variability of the depth of the cloud layer (1 - 2 km thick) and of the sub-cloud boundary layer ( 1 km thick). Layer depths and partial water vapor columns within the layers may vary by up to a factor of 2, and on a large range of horizontal scales. Occasionally, very dry, up

  16. Facile Fabrication of Boron-Doped Titania Nanopowders by Atmospheric Pressure Chemical Vapor Synthesis Route and its Photocatalytic Activity

    Directory of Open Access Journals (Sweden)

    K. Saberyan

    2014-04-01

    Full Text Available The Atmospheric Pressure Chemical Vapor Synthesis (APCVS route is a process that can be used for the synthesis of doped-nanocrystalline powders with very small crystallite sizes having a narrow particle size distribution and high purity. In this study, APCVS technique was used to prepare boron-doped titania nanopowders. The effects of temperature, borate flow rate and water flow rate on the amount of doped boron were studied. The resultant powders were characterized by inductively coupled plasma (ICP, X-ray diffraction (XRD, nitrogen adsorption technique (BET, UV-visible DRS spectroscopy, scanning electron microscopy (SEM, and transmission electron microscopy (TEM. The optimum boron precursor flow rate was 80 sccm. The highest amount of doped boron was attained when water flow rate was 900 sccm. In comparison to the pristine TiO2, the boron-doped TiO2 nanoparticles showed blue-shift in band-gap energy of the samples.

  17. 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.; hide

    2012-01-01

    The MOHAVE-2009 campaign brought together diverse instrumentation for measuring atmospheric water vapor. We report on the participation of the ALVICE (Atmospheric Laboratory for Validation, Interagency Collaboration and Education) mobile laboratory in the MOHAVE-2009 campaign. In appendices we also report on the performance of the corrected Vaisala RS92 radiosonde measurements during the campaign, on a new radiosonde based calibration algorithm that reduces the influence of atmospheric variability on the derived calibration constant, and on other results of the ALVICE deployment. The MOHAVE-2009 campaign permitted the Raman lidar systems participating to discover and address measurement biases in the upper troposphere and lower stratosphere. The ALVICE lidar system was found to possess a wet bias which was attributed to fluorescence of insect material that was deposited on the telescope early in the mission. Other sources of wet biases are discussed and data from other Raman lidar systems are investigated, revealing that wet biases in upper tropospheric (UT) and lower stratospheric (LS) water vapor measurements appear to be quite common in Raman lidar systems. Lower stratospheric climatology of water vapor is investigated both as a means to check for the existence of these wet biases in Raman lidar data and as a source of correction for the bias. A correction technique is derived and applied to the ALVICE lidar water vapor profiles. Good agreement is found between corrected ALVICE lidar measurments and those of RS92, frost point hygrometer and total column water. The correction is offered as a general method to both quality control Raman water vapor lidar data and to correct those data that have signal-dependent bias. The influence of the correction is shown to be small at regions in the upper troposphere where recent work indicates detection of trends in atmospheric water vapor may be most robust. The correction shown here holds promise for permitting useful upper

  18. Water vapor sorption properties of cellulose nanocrystals and nanofibers using dynamic vapor sorption apparatus.

    Science.gov (United States)

    Guo, Xin; Wu, Yiqiang; Xie, Xinfeng

    2017-10-27

    Hygroscopic behavior is an inherent characteristic of nanocellulose which strongly affects its applications. In this study, the water vapor sorption behavior of four nanocellulose samples, such as cellulose nanocrystals and nanofibers with cellulose I and II structures (cellulose nanocrystals (CNC) I, CNC II, cellulose nanofibers (CNF) I, and CNF II) were studied by dynamic vapor sorption. The highly reproducible data including the running time, real-time sample mass, target relative humidity (RH), actual RH, and isotherm temperature were recorded during the sorption process. In analyzing these data, significant differences in the total running time, equilibrium moisture content, sorption hysteresis and sorption kinetics between these four nanocellulose samples were confirmed. It was important to note that CNC I, CNC II, CNF I, and CNF II had equilibrium moisture contents of 21.4, 28.6, 33.2, and 38.9%, respectively, at a RH of 95%. Then, the sorption kinetics behavior was accurately described by using the parallel exponential kinetics (PEK) model. Furthermore, the Kelvin-Voigt model was introduced to interpret the PEK behavior and calculate the modulus of these four nanocellulose samples.

  19. The Influence of Summertime Convection Over Southeast Asia on Water Vapor in the Tropical Stratosphere

    Science.gov (United States)

    Wright, J. S.; Fu, R.; Fueglistaler, S.; Liu, Y. S.; Zhang, Y.

    2011-01-01

    The relative contributions of Southeast Asian convective source regions during boreal summer to water vapor in the tropical stratosphere are examined using Lagrangian trajectories. Convective sources are identified using global observations of infrared brightness temperature at high space and time resolution, and water vapor transport is simulated using advection-condensation. Trajectory simulations are driven by three different reanalysis data sets, GMAO MERRA, ERA-Interim, and NCEP/NCAR, to establish points of consistency and evaluate the sensitivity of the results to differences in the underlying meteorological fields. All ensembles indicate that Southeast Asia is a prominent boreal summer source of tropospheric air to the tropical stratosphere. Three convective source domains are identified within Southeast Asia: the Bay of Bengal and South Asian subcontinent (MON), the South China and Philippine Seas (SCS), and the Tibetan Plateau and South Slope of the Himalayas (TIB). Water vapor transport into the stratosphere from these three domains exhibits systematic differences that are related to differences in the bulk characteristics of transport. We find air emanating from SCS to be driest, from MON slightly moister, and from TIB moistest. Analysis of pathways shows that air detrained from convection over TIB is most likely to bypass the region of minimum absolute saturation mixing ratio over the equatorial western Pacific; however, the impact of this bypass mechanism on mean water vapor in the tropical stratosphere at 68 hPa is small 0.1 ppmv). This result contrasts with previously published hypotheses, and it highlights the challenge of properly quantifying fluxes of atmospheric humidity.

  20. Monitoring the water vapor isotopic composition in the temperate North Atlantic

    Science.gov (United States)

    Sveinbjörnsdottir, Arny E.; Steen-Larsen, Hans Christian; Jonsson, Thorsteinn; Johnsen, Sigfus J.

    2013-04-01

    Water stable isotopes have during many decades been used as climate proxies and indicators for variations in the hydrological cycle. However we are to a great extent still using simple empirical relationships without any deeper theoretical understanding. In order to properly relate changes in the climate and hydrological cycle to changes in the observed stable water isotopic signal we must understand the underlying physical processes. Furthermore it is a challenge for General Climate Models to adequately represent the isotopes in the hydrological cycle because of lack of in-situ measurements of the atmospheric water-vapor composition in the source regions. During the fall of 2010 we installed an autonomous water vapor spectroscopy laser (from Los Gatos Research) in a lighthouse on the South Coast of Iceland (63.83 N 21.47W) with the plan to be operational for several years. The purpose of this installation was through monitoring of the water vapor isotopic composition to understand the physical processes governing the isotopic composition of the water vapor evaporated from the ocean as well as the processes of mixing between the free troposphere and marine boundary layer. Because of the remoteness of the monitoring site and simple topography we are able to isolate the 'fingerprint' on the isotopic signal in the water vapor from respectively the ocean and the interior highland leading to a near perfect case-study area. Using back-trajectories we find a strong influence of the origin of the air masses on the measured isotopic composition. The mixing of the marine-boundary layer is found to strongly influence the measured isotopic composition. The second order isotopic parameter, d-excess, is contrary to theory and previous observations found not to depend on the relative humidity. However we do find a good correlation between the d-excess and the measured isotopic composition. We speculate that the lack of correlation between d-excess and relative humidity can be

  1. Atmospheric pressure chemical vapor deposition (APCVD) grown bi-layer graphene transistor characteristics at high temperature

    KAUST Repository

    Qaisi, Ramy M.

    2014-05-15

    We report the characteristics of atmospheric chemical vapor deposition grown bilayer graphene transistors fabricated on ultra-scaled (10 nm) high-κ dielectric aluminum oxide (Al2O3) at elevated temperatures. We observed that the drive current increased by >400% as temperature increased from room temperature to 250 °C. Low gate leakage was maintained for prolonged exposure at 100 °C but increased significantly at temperatures >200 °C. These results provide important insights for considering chemical vapor deposition graphene on aluminum oxide for high temperature applications where low power and high frequency operation are required. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Water vapor toward starless cores: The Herschel view

    Science.gov (United States)

    Caselli, P.; Keto, E.; Pagani, L.; Aikawa, Y.; Yıldız, U. A.; van der Tak, F. F. S.; Tafalla, M.; Bergin, E. A.; Nisini, B.; Codella, C.; van Dishoeck, E. F.; Bachiller, R.; Baudry, A.; Benedettini, M.; Benz, A. O.; Bjerkeli, P.; Blake, G. A.; Bontemps, S.; Braine, J.; Bruderer, S.; Cernicharo, J.; Daniel, F.; di Giorgio, A. M.; Dominik, C.; Doty, S. D.; Encrenaz, P.; Fich, M.; Fuente, A.; Gaier, T.; Giannini, T.; Goicoechea, J. R.; de Graauw, Th.; Helmich, F.; Herczeg, G. J.; Herpin, F.; Hogerheijde, M. R.; Jackson, B.; Jacq, T.; Javadi, H.; Johnstone, D.; Jørgensen, J. K.; Kester, D.; Kristensen, L. E.; Laauwen, W.; Larsson, B.; Lis, D.; Liseau, R.; Luinge, W.; Marseille, M.; McCoey, C.; Megej, A.; Melnick, G.; Neufeld, D.; Olberg, M.; Parise, B.; Pearson, J. C.; Plume, R.; Risacher, C.; Santiago-García, J.; Saraceno, P.; Shipman, R.; Siegel, P.; van Kempen, T. A.; Visser, R.; Wampfler, S. F.; Wyrowski, F.

    2010-10-01

    Aims: Previous studies by the satellites SWAS and Odin provided stringent upper limits on the gas phase water abundance of dark clouds (x(H2O) 7000 AU and ≃2 × 10-10 toward the center. The radiative transfer analysis shows that this is consistent with a x(o-H2O) profile peaking at ≃10-8, 0.1 pc away from the core center, where both freeze-out and photodissociation are negligible. Conclusions: Herschel has provided the first measurement of water vapor in dark regions. Column densities of o-H2O are low, but prestellar cores such as L1544 (with their high central densities, strong continuum, and large envelopes) appear to be very promising tools to finally shed light on the solid/vapor balance of water in molecular clouds and oxygen chemistry in the earliest stages of star formation. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.

  3. Remote sensing evidence for regolith water vapor sources on Mars

    Science.gov (United States)

    Huguenin, R. L.; Clifford, S. M.

    1982-01-01

    McCord et al. (1977) have presented earth-based photometric imaging data of an event associated with the 1973 dust storm on Mars. The initial dust cloud in Solis Lacus and two regions to the north and south appeared anomalously bright at blue wavelengths. Water frosts, hazes, and/or clouds were identified, and it was suggested that the water responsible for these findings may have originated from Solis Lacus. More recently, a more intensive review of the observational record of Mars was undertaken. Earth-based telescope observations and data from the Mariner and Viking missions have revealed that Solis Lacus has been a center of repeated activity. Persistent activity in the vicinity of Noachis-Hellespontus and in the border regions of Syrtis Major was also discovered. A review of the observations is provided and possible interpretations are discussed. The obtained results appear to support the original proposal that Solis Lacus may be a source of water vapor. Noachis-Hellespontus seems to be a similar vapor source

  4. Water cycle dynamic increases resilience of vegetation under higher atmospheric carbon dioxide concentration

    Science.gov (United States)

    Lemordant, L. A.; Gentine, P.; Stéfanon, M.; Drobinski, P. J.; Fatichi, S.

    2015-12-01

    Plant stomata couple the energy, water and carbon cycles. Photosynthesis requires stomata to open to take up carbon dioxide. In the process water vapor is released as transpiration. As atmospheric CO2 concentration rises, for the same amount of CO2 uptake, less water vapor is transpired, translating into higher water use efficiency. Reduced water vapor losses will increase soil water storage if the leaf area coverage remains similar. This will in turn alter the surface energy partitioning: more heat will be dissipated as sensible heat flux, resulting in possibly higher surface temperatures. In contrast with this common hypothesis, our study shows that the water saved during the growing season by increased WUE can be mobilized by the vegetation and help reduce the maximum temperature of mid-latitude heat waves. The large scale meteorological conditions of 2003 are the basis of four regional model simulations coupling an atmospheric model to a surface model. We performed two simulations with respectively 2003 (CTL) and 2100 (FUT) atmospheric CO2 applied to both the atmospheric and surface models. A third (RAD) and a fourth (FER) simulations are run with 2100 CO2 concentration applied to respectively the atmospheric model only and the surface model only. RAD investigates the impact of the radiative forcing, and FER the response to vegetation CO2 fertilization. Our results show that the water saved through higher water use efficiency during the growing season enabled by higher atmospheric carbon dioxide concentrations helps the vegetation to cope during severe heat and dryness conditions in the summer of mid-latitude climate. These results demonstrate that consideration of the vegetation carbon cycle is essential to model the seasonal water cycle dynamic and land-atmosphere interactions, and enhance the accuracy of the model outputs especially for extreme events. They also have important implications for the future of agriculture, water resources management, ecosystems

  5. 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.

  6. The SPARC water vapor assessment II: intercomparison of satellite and ground-based microwave measurements

    Directory of Open Access Journals (Sweden)

    G. E. Nedoluha

    2017-12-01

    Full Text Available As part of the second SPARC (Stratosphere–troposphere Processes And their Role in Climate water vapor assessment (WAVAS-II, we present measurements taken from or coincident with seven sites from which ground-based microwave instruments measure water vapor in the middle atmosphere. Six of the ground-based instruments are part of the Network for the Detection of Atmospheric Composition Change (NDACC and provide datasets that can be used for drift and trend assessment. We compare measurements from these ground-based instruments with satellite datasets that have provided retrievals of water vapor in the lower mesosphere over extended periods since 1996. We first compare biases between the satellite and ground-based instruments from the upper stratosphere to the upper mesosphere. We then show a number of time series comparisons at 0.46 hPa, a level that is sensitive to changes in H2O and CH4 entering the stratosphere but, because almost all CH4 has been oxidized, is relatively insensitive to dynamical variations. Interannual variations and drifts are investigated with respect to both the Aura Microwave Limb Sounder (MLS; from 2004 onwards and each instrument's climatological mean. We find that the variation in the interannual difference in the mean H2O measured by any two instruments is typically  ∼  1%. Most of the datasets start in or after 2004 and show annual increases in H2O of 0–1 % yr−1. In particular, MLS shows a trend of between 0.5 % yr−1 and 0.7 % yr−1 at the comparison sites. However, the two longest measurement datasets used here, with measurements back to 1996, show much smaller trends of +0.1 % yr−1 (at Mauna Loa, Hawaii and −0.1 % yr−1 (at Lauder, New Zealand.

  7. Time variant layer control in atmospheric pressure chemical vapor deposition based growth of graphene

    KAUST Repository

    Qaisi, Ramy M.

    2013-04-01

    Graphene is a semi-metallic, transparent, atomic crystal structure material which is promising for its high mobility, strength and transparency - potentially applicable for radio frequency (RF) circuitry and energy harvesting and storage applications. Uniform (same number of layers), continuous (not torn or discontinuous), large area (100 mm to 200 mm wafer scale), low-cost, reliable growth are the first hand challenges for its commercialization prospect. We show a time variant uniform (layer control) growth of bi- to multi-layer graphene using atmospheric chemical vapor deposition system. We use Raman spectroscopy for physical characterization supported by electrical property analysis. © 2013 IEEE.

  8. Porous tungsten prepared by atmospheric-pressure chemical vapor deposition with WF6 and its characterization

    Science.gov (United States)

    Li, Ying; Yu, Xiaodong; Tan, Chengwen; Wang, Fuchi; Ma, Honglei; Yue, Jintao

    2017-05-01

    Porous tungsten (W) is used in aeronautic and aerospace engineering, power electronics field and metallurgical industry. In this study, porous W with 98wt% W was prepared on a carbon foam substrate by atmospheric-pressure chemical vapor deposition (CVD) with tungsten fluoride (WF6) as the precursor. The porous W with 78.1346% porosity displayed a pure α-W phase and the uniform surface. The mode pore diameter of porous W is 208.0 µm. In a compression test, the fracture strength of porous W is 20.3 MPa.

  9. Evaluation of Vapor Pressure Estimation Methods for Use in Simulating the Dynamic of Atmospheric Organic Aerosols

    Directory of Open Access Journals (Sweden)

    A. J. Komkoua Mbienda

    2013-01-01

    Lee and Kesler (LK, and Ambrose-Walton (AW methods for estimating vapor pressures ( are tested against experimental data for a set of volatile organic compounds (VOC. required to determine gas-particle partitioning of such organic compounds is used as a parameter for simulating the dynamic of atmospheric aerosols. Here, we use the structure-property relationships of VOC to estimate . The accuracy of each of the aforementioned methods is also assessed for each class of compounds (hydrocarbons, monofunctionalized, difunctionalized, and tri- and more functionalized volatile organic species. It is found that the best method for each VOC depends on its functionality.

  10. Interaction of binary cuprates with oxygen and water vapor at temperatures of 200-400°C

    Science.gov (United States)

    Bobylev, I. B.; Naumov, S. V.; Zyuzeva, N. A.

    2013-08-01

    Interaction of binary cuprates with oxygen and water vapor at T = 200-400°C has been studied. It has been established that only compounds containing oxygen vacancy chains in their structure can absorb oxygen and moisture from annealing atmosphere. Absorption of oxygen brings about decrease in the lattice parameters while embedding of OH- groups leads to their growth. In contrast to YBa2Cu3O y , binary cuprates do not undergo phase transitions in interaction with the atmosphere. Saturation with water and formation of oxyhydroxides is followed by their hydrolytic decomposition involving formation of simpler oxides and hydroxides.

  11. Ricor's Nanostar water vapor compact cryopump: applications and model overview

    Science.gov (United States)

    Harris, Rodney S.; Nachman, Ilan; Tauber, Tomer; Kootzenko, Michael; Barak, Boris; Aminov, Eli; Gover, Dan

    2017-05-01

    Ricor Systems has developed a compact, single stage cryopump that fills the gap where GM and other type cryopumps can't fit in. Stirling cycle technology is highly efficient and is the primary cryogenic technology for use in IR, SWIR, HOT FPA, and other IR detector technology in military, security, and aerospace applications. Current GM based dual stage cryopumps have been the legacy type water vapor pumping system for more than 50 years. However, the typically large cryopanel head, compressor footprint, and power requirements make them not cost and use effective for small, tabletop evaporation / sputtering systems, portable analysis systems, and other systems requiring small volume vacuum creation from medium, high, and UHV levels. This single stage cryopump works well in-line with diffusion and molecular turbopumps. Studies have shown effective cooperation with non-evaporable getter technology as well for UHV levels. Further testing in this area are ongoing. Temperatures created by Stirling cycle cryogenic coolers develop a useful temperature range of 40 to 150K. Temperatures of approximately 100 K are sufficient to condense water and all hydrocarbons oil vapors.

  12. Exploring the Elevated Water Vapor Signal Associated with Biomass Burning Aerosol over the Southeast Atlantic Ocean

    Science.gov (United States)

    Pistone, Kristina; Redemann, Jens; Wood, Rob; Zuidema, Paquita; Flynn, Connor; LeBlanc, Samuel; Noone, David; Podolske, James; Segal Rozenhaimer, Michal; Shinozuka, Yohei; hide

    2017-01-01

    The quantification of radiative forcing due to the cumulative effects of aerosols, both directly and on cloud properties, remains the biggest source of uncertainty in our understanding of the physical climate. How the magnitude of these effects may be modified by meteorological conditions is an important aspect of this question. The Southeast Atlantic Ocean (SEA), with seasonal biomass burning (BB) smoke plumes overlying a persistent stratocumulus cloud deck, offers a perfect natural observatory in which to study the complexities of aerosol-cloud interactions. The NASA ORACLES (ObseRvations of Aerosols above CLouds and their intEractionS) campaign consists of three field deployments over three years (2016-2018) with the goal of gaining a better understanding of the complex processes (direct and indirect) by which BB aerosols affect clouds. We present results from the first ORACLES field deployment, which took place in September 2016 out of Walvis Bay, Namibia. Two NASA aircraft were flown with a suite of aerosol, cloud, radiation, and meteorological instruments for remote-sensing and in-situ observations. A strong correlation was observed between the aircraft-measured pollution indicators (carbon monoxide and aerosol properties) and atmospheric water vapor content, at all altitudes. Atmospheric reanalysis indicates that convective dynamics over the continent, near likely contribute to this elevated signal. Understanding the mechanisms by which water vapor covaries with plume strength is important to quantifying the magnitude of the aerosol direct and semi-direct effects in the region.

  13. Reaction rates of Criegee intermediates with water vapor and hydrogen sulfide

    Science.gov (United States)

    Smith, M. C.; Boering, K. A.

    2016-12-01

    Criegee intermediates are byproducts of the reaction of alkenes with ozone. Bimolecular reactions of Criegee intermediates can lead to the production of low-volatility organic compounds and acids in the atmosphere, which in turn play a role in determining the concentration, size, and optical properties of aerosols. Recently, a novel method for producing measurable quantities of stabilized Criegee intermediates in the laboratory paved the way for the development of new experimental techniques to study their chemical properties and predict their importance in the atmosphere. Our lab uses transient UV absorption spectroscopy to measure the formation and decay of Criegee intermediates in a flow cell, using 8-pass absorption of a bright plasma light source combined with sensitive balanced photodiode detection. Here we measured the transient absorption of CH2OO and obtained rate coefficients for its reaction with water dimer from 283 to 324 K. The fast reaction of CH2OO with water dimer is thought to dominate CH2OO removal in the atmosphere, but reaction rates can vary considerably under different conditions of temperature, humidity, and pressure. The rate of the reaction of CH2OO with water dimer was found to exhibit a strong negative temperature dependence. Due to the strong temperature dependence, and shifting competition between water dimer and water monomer (which has a positive temperature dependence), the effective loss rate of CH2OO by reaction with water vapor is highly sensitive to atmospheric conditions. We also present the first measurements of the reaction rate between CH2OO and hydrogen sulfide, which is analogous to the water molecule and may have significance in areas with volcanic activity.

  14. Correcting attenuated total reflection-fourier transform infrared spectra for water vapor and carbon dioxide

    DEFF Research Database (Denmark)

    Bruun, Susanne Wrang; Kohler, Achim; Adt, Isabelle

    2006-01-01

    an absorption band from either water vapor or CO(2). From two calibration data sets, gas model spectra were estimated in each of the four spectral regions, and these model spectra were applied for correction of gas absorptions in two independent test sets (spectra of aqueous solutions and a yeast biofilm (C....... albicans) growing on an ATR crystal, respectively). The amounts of the atmospheric gases as expressed by the model spectra were estimated by regression, using second-derivative transformed spectra, and the estimated gas spectra could subsequently be subtracted from the sample spectra. For spectra...... of the growing yeast biofilm, the gas correction revealed otherwise hidden variations of relevance for modeling the growth dynamics. As the presented method improved the interpretation of the principle component analysis (PCA) models, it has proven to be a valuable tool for filtering atmospheric variation in ATR...

  15. Modeling and Prediction of Soil Water Vapor Sorption Isotherms

    DEFF Research Database (Denmark)

    Arthur, Emmanuel; Tuller, Markus; Moldrup, Per

    2015-01-01

    Soil water vapor sorption isotherms describe the relationship between water activity (aw) and moisture content along adsorption and desorption paths. The isotherms are important for modeling numerous soil processes and are also used to estimate several soil (specific surface area, clay content......, cation exchange capacity) and engineering properties (e.g., swelling potential). Our objectives for this work were to: (i) evaluate the potential of several theoretical and empirical isotherm models to accurately describe measured moisture adsorption/desorption isotherms (aw range of 0.03 to 0.......93) for a wide range of soils; and (ii) develop and test regression models for estimating the isotherms from clay content. Preliminary results show reasonable fits of the majority of the investigated empirical and theoretical models to the measured data although some models were not capable to fit both sorption...

  16. Stable isotope tracers of water vapor sources in the Atacama Desert, Northern Chile: a pilot study on the Chajnantor Plateau

    Science.gov (United States)

    Samuels, K. E.; Galewsky, J.; Sharp, Z. D.; Rella, C.; Ward, D.

    2010-12-01

    Subtropical deserts form in response to the interaction of large-scale processes, including atmospheric circulation and oceanic currents, with local features like topography. The degree to which each of these factors controls desert formation and the anticipated impacts of variations in each as climate changes, however, are poorly understood. Stable isotope compositions of water vapor in desert air can help to distinguish between moisture sources and processes that control aridity. The Atacama Desert, located in northern Chile between latitudes 23S and 27S, provides a natural laboratory in which to test the degree to which water vapor isotopologues enable the distinction between processes that control humidity, including the Hadley Circulation, the cold Humboldt Current off the coast of Chile, and the orographic effect of the Andes, in this subtropical desert. Water vapor isotopologues and concentrations were measured in real time using a cavity-ringdown spectrometer deployed on the Chajnantor Plateau over a three-week period from mid-July early August 2010. The elevation of the Plateau, 5000 m amsl (~550 hPa), places it above the boundary layer, allowing the evaluation of the Rayleigh fractionation model from the coast inland. Values reported by the instrument were verified with air samples taken at the coast and the Plateau, which were analyzed on an MAT-252 mass spectrometer. Water vapor concentrations and δD values varied spatially and temporally. Water vapor concentrations on the Plateau ranged from 200 to 3664 ppmv with a mean value of 536 ppmv. In contrast, water vapor concentrations at the coast were approximately 10000 ppmv, and at Yungay, 60 km inland, water vapor concentrations ranged from 1300 to 2000 ppmv from morning to evening. δD values on the Plateau ranged from -526‰ to -100‰ with a mean value of 290‰ with enriched values correlated to periods with higher water vapor concentrations. There are no strong diurnal variations in water vapor

  17. Feasibility of tropospheric water vapor profiling using infrared heterodyne differential absorption lidar

    Energy Technology Data Exchange (ETDEWEB)

    Grund, C.J.; Hardesty, R.M. [National Oceanic and Atmospheric Administration Environmental Technology Laboratoy, Boulder, CO (United States); Rye, B.J. [Univ. of Colorado, Boulder, CO (United States)

    1996-04-01

    The development and verification of realistic climate model parameterizations for clouds and net radiation balance and the correction of other site sensor observations for interferences due to the presence of water vapor are critically dependent on water vapor profile measurements. In this study, we develop system performance models and examine the potential of infrared differential absoroption lidar (DIAL) to determine the concentration of water vapor.

  18. Water vapor in the spectrum of the extrasolar planet HD 189733b. I. The transit

    Energy Technology Data Exchange (ETDEWEB)

    McCullough, P. R.; Crouzet, N. [Space Telescope Science Institute, Baltimore, MD 21218 (United States); Deming, D. [Department of Astronomy, University of Maryland, College Park, MD 20742 (United States); Madhusudhan, N., E-mail: pmcc@stsci.edu [Yale Center for Astronomy and Astrophysics, Yale University, New Haven, CT 06511 (United States)

    2014-08-10

    We report near-infrared spectroscopy of the gas giant planet HD 189733b in transit. We used the Hubble Space Telescope Wide Field Camera 3 (HST WFC3) with its G141 grism covering 1.1 μm to 1.7 μm and spatially scanned the image across the detector at 2'' s{sup –1}. When smoothed to 75 nm bins, the local maxima of the transit depths in the 1.15 μm and 1.4 μm water vapor features are, respectively, 83 ± 53 ppm and 200 ± 47 ppm greater than the local minimum at 1.3 μm. We compare the WFC3 spectrum with the composite transit spectrum of HD 189733b assembled by Pont et al., extending from 0.3 μm to 24 μm. Although the water vapor features in the WFC3 spectrum are compatible with the model of non-absorbing, Rayleigh-scattering dust in the planetary atmosphere, we also re-interpret the available data with a clear planetary atmosphere. In the latter interpretation, the slope of increasing transit depth with shorter wavelengths from the near infrared, through the visible, and into the ultraviolet is caused by unocculted star spots, with a smaller contribution of Rayleigh scattering by molecular hydrogen in the planet's atmosphere. At relevant pressures along the terminator, our model planetary atmosphere's temperature is ∼700 K, which is below the condensation temperatures of sodium- and potassium-bearing molecules, causing the broad wings of the spectral lines of Na I and K I at 0.589 μm and 0.769 μm to be weak.

  19. Analysis of the retention of water vapor on silica gel; Analisis de la retencion del vapor de agua en silica gel

    Energy Technology Data Exchange (ETDEWEB)

    Herranz, M.; Pinilla, J. L.; Alegria, N.; Idoeta, R.; Legarda, F.

    2011-07-01

    Among the various sampling systems tritium content in the atmosphere as water vapor, one of the most basic and, therefore, of widespread use in the environmental field, is the retention on silica gel. However, the behavior of the collection efficiency of silica gel under varying conditions of air temperature and relative humidity makes it difficult to define the amount of this necessary for proper completion of sampling, especially in situations of prolonged sampling. This paper presents partial results obtained in a study on the analysis of these efficiencies under normal conditions of sampling. (Author)

  20. Remote sensing of atmospheric water content from Bhaskara SAMIR data. [using statistical linear regression analysis

    Science.gov (United States)

    Gohil, B. S.; Hariharan, T. A.; Sharma, A. K.; Pandey, P. C.

    1982-01-01

    The 19.35 GHz and 22.235 GHz passive microwave radiometers (SAMIR) on board the Indian satellite Bhaskara have provided very useful data. From these data has been demonstrated the feasibility of deriving atmospheric and ocean surface parameters such as water vapor content, liquid water content, rainfall rate and ocean surface winds. Different approaches have been tried for deriving the atmospheric water content. The statistical and empirical methods have been used by others for the analysis of the Nimbus data. A simulation technique has been attempted for the first time for 19.35 GHz and 22.235 GHz radiometer data. The results obtained from three different methods are compared with radiosonde data. A case study of a tropical depression has been undertaken to demonstrate the capability of Bhaskara SAMIR data to show the variation of total water vapor and liquid water contents.

  1. Aerosol absorption measurement at SWIR with water vapor interference using a differential photoacoustic spectrometer.

    Science.gov (United States)

    Zhu, Wenyue; Liu, Qiang; Wu, Yi

    2015-09-07

    Atmospheric aerosol plays an important role in atmospheric radiation balance through absorbing and scattering the solar radiation, which changes local weather and global climate. Accurate measurement is highly requested to estimate the radiative effects and climate effects of atmospheric aerosol. Photoacoustic spectroscopy (PAS) technique, which observes the aerosols on their natural suspended state and is insensitive to light scattering, is commonly recognized as one of the best candidates to measure the optical absorption coefficient (OAC) of aerosols. In the present work, a method of measuring aerosol OAC at the wavelength where could also be absorbed by water vapor was proposed and corresponding measurements of the absorption properties of the atmospheric aerosol at the short wave infrared (SWIR, 1342 nm) wavelength were carried out. The spectrometer was made up of two high performance homemade photoacoustic cells. To improve the sensitivity, several methods were presented to control the noise derived from gas flow and vibration from the sampling pump. Calibration of the OAC and properties of the system were also studied in detail. Using the established PAS instrument, measurement of the optical absorption properties of the atmospheric aerosol were carried out in laboratory and field environment.

  2. Cold Water Vapor in the Barnard 5 Molecular Cloud

    Science.gov (United States)

    Wirstrom, E. S.; Charnley, S. B.; Persson, C. M.; Buckle, J. V.; Cordiner, M. A.; Takakuwa, S.

    2014-01-01

    After more than 30 yr of investigations, the nature of gas-grain interactions at low temperatures remains an unresolved issue in astrochemistry. Water ice is the dominant ice found in cold molecular clouds; however, there is only one region where cold ((is) approximately 10 K) water vapor has been detected-L1544. This study aims to shed light on ice desorption mechanisms under cold cloud conditions by expanding the sample. The clumpy distribution of methanol in dark clouds testifies to transient desorption processes at work-likely to also disrupt water ice mantles. Therefore, the Herschel HIFI instrument was used to search for cold water in a small sample of prominent methanol emission peaks. We report detections of the ground-state transition of o-H2O (J = 110-101) at 556.9360 GHz toward two positions in the cold molecular cloud, Barnard 5. The relative abundances of methanol and water gas support a desorption mechanism which disrupts the outer ice mantle layers, rather than causing complete mantle removal.

  3. Energy and water vapor transport across a simplified cloud-clear air interface

    Science.gov (United States)

    Gallana, L.; Di Savino, S.; De Santi, F.; Iovieno, M.; Tordella, D.

    2014-11-01

    We consider a simplified physics of the could interface where condensation, evaporation and radiation are neglected and momentum, thermal energy and water vapor transport is represented in terms of the Boussinesq model coupled to a passive scalar transport equation for the vapor. The interface is modeled as a layer separating two isotropic turbulent regions with different kinetic energy and vapor concentration. In particular, we focus on the small scale part of the inertial range of the atmospheric boundary layer as well as on the dissipative range of scales which are important to the micro-physics of warm clouds. We have numerically investigated stably stratified interfaces by locally perturbing at an initial instant the standard temperature lapse rate at the cloud interface and then observing the temporal evolution of the system. When the buoyancy term becomes of the same order of the inertial one, we observe a spatial redistribution of the kinetic energy which produce a concomitant pit of kinetic energy within the mixing layer. In this situation, the mixing layer contains two interfacial regions with opposite kinetic energy gradient, which in turn produces two intermittent sublayers in the velocity fluctuations field. This changes the structure of the field with respect to the corresponding non-stratified shearless mixing: the communication between the two turbulent region is weak, and the growth of the mixing layer stops. These results are discussed with respect to Large Eddy Simulations data for the Planetary Boundary Layers.

  4. The Observed Relationship Between Water Vapor and Ozone in the Tropical Tropopause Saturation Layer and the Influence of Meridional Transport

    Science.gov (United States)

    Selkirk, Henry B.; Schoeberl, M. R.; Olsen, M. A.; Douglass, A. R.

    2011-01-01

    We examine balloonsonde observations of water vapor and ozone from three Ticosonde campaigns over San Jose, Costa Rica [10 N, 84 W] during northern summer and a fourth during northern winter. The data from the summer campaigns show that the uppermost portion of the tropical tropopause layer between 360 and 380 K, which we term the tropopause saturation layer or TSL, is characterized by water vapor mixing ratios from proximately 3 to 15 ppmv and ozone from approximately 50 ppbv to 250 ppbv. In contrast, the atmospheric water vapor tape recorder at 380 K and above displays a more restricted 4-7 ppmv range in water vapor mixing ratio. From this perspective, most of the parcels in the TSL fall into two classes - those that need only additional radiative heating to rise into the tape recorder and those requiring some combination of additional dehydration and mixing with drier air. A substantial fraction of the latter class have ozone mixing ratios greater than 150 ppbv, and with water vapor greater than 7 ppmv this air may well have been transported into the tropics from the middle latitudes in conjunction with high-amplitude equatorial waves. We examine this possibility with both trajectory analysis and transport diagnostics based on HIRDLS ozone data. We apply the same approach to study the winter season. Here a very different regime obtains as the ozone-water vapor scatter diagram of the sonde data shows the stratosphere and troposphere to be clearly demarcated with little evidence of mixing in of middle latitude air parcels.

  5. Biophysical controls on carbon and water vapor fluxes across a grassland climatic gradient in the United States

    Energy Technology Data Exchange (ETDEWEB)

    Wagle, Pradeep; Xiao, Xiangming; Scott, Russell L.; Kolb, Thomas E.; Cook, David R.; Brunsell, Nathaniel; Baldocchi, Dennis D.; Basara, Jeffrey; Matamala, Roser; Zhou, Yuting; Bajgain, Rajen

    2015-12-01

    Understanding of the underlying causes of spatial variation in exchange of carbon and water vapor fluxes between grasslands and the atmosphere is crucial for accurate estimates of regional and global carbon and water budgets, and for predicting the impact of climate change on biosphere–atmosphere feedbacks of grasslands. We used ground-based eddy flux and meteorological data, and the Moderate Resolution Imaging Spectroradiometer (MODIS) enhanced vegetation index (EVI) from 12 grasslands across the United States to examine the spatial variability in carbon and water vapor fluxes and to evaluate the biophysical controls on the spatial patterns of fluxes. Precipitation was strongly associated with spatial and temporal variability in carbon and water vapor fluxes and vegetation productivity. Grasslands with annual average precipitation <600 mm generally had neutral annual carbon balance or emitted small amount of carbon to the atmosphere. Despite strong coupling between gross primary production (GPP)and evapotranspiration (ET) across study sites, GPP showed larger spatial variation than ET, and EVI had a greater effect on GPP than on ET. Consequently, large spatial variation in ecosystem water use efficiency (EWUE = annual GPP/ET; varying from 0.67 ± 0.55 to 2.52 ± 0.52 g C mm⁻¹ET) was observed. Greater reduction in GPP than ET at high air temperature and vapor pressure deficit caused a reduction in EWUE in dry years, indicating a response which is opposite than what has been reported for forests. Our results show that spatial and temporal variations in ecosystem carbon uptake, ET, and water use efficiency of grasslands were strongly associated with canopy greenness and coverage, as indicated by EVI.

  6. Isotopic equilibrium between precipitation and water vapor: evidence from continental rains in central Kenya

    Science.gov (United States)

    Soderberg, K.; Gerlein, C.; Kemeny, P. C.; Caylor, K. K.

    2013-12-01

    An accurate understanding of the relationships between the isotopic composition of liquid water and that of water vapor in the environment can help describe hydrologic processes across many scales. One such relationship is the isotopic equilibrium between falling raindrops and the surrounding vapor. The degree of equilibration is used to model the isotopic composition of precipitation in isotope-enable general circulation models and land-atmosphere exchange models. Although this equilibrium has been a topic of isotope hydrology research for more than four decades, few studies have included vapor measurements to validate modeling efforts. Recent advances in laser technology have allowed for in situ vapor measurements at high temporal resolution (e.g., >1 Hz). Here we present concomitant rain and vapor measurements for a series of 17 rain events during the 'Continental' rainy season (June through August) at Mpala Research Center in central Kenya. Rain samples (n=218) were collected at intervals of 2 to 35 minutes (median of 3 minutes) depending on the rain rate (0.4 to 10.5 mm/hr). The volume-weighted mean rain values for δ18O, δ2H and D-excess (δ2H - 8* δ18O) were 0.1 ‰, 10.7 ‰, and 10.1 ‰. These values are more enriched than the annual weighted means reported for the area (-2.2 ‰, -7.6 ‰, and 11.0 ‰, respectively). Vapor was measured continuously at ~2Hz (DLT-100, Los Gatos Research), with an inverted funnel intake 4m above the ground surface. The mean vapor isotopic composition during the rain events was -10.0 +/- 1.2 ‰ (1 σ) for δ18O and -73.9 +/- 7.0 ‰ for δ2H. The difference between the rain sample isotopic composition and that of liquid in isotopic equilibrium with the corresponding vapor at the ambient temperature was 0.8 +/- 2.2 ‰ for δ18O and 6.2 +/- 7.0 ‰ for δ2H. This disequilibrium was found to correlate with the natural log of rain rate (R2 of 0.26 for δ18O and 0.46 for δ2H), with lower rain rates having larger

  7. A process-based evapotranspiration model incorporating coupled soil water-atmospheric controls

    Science.gov (United States)

    Haghighi, Erfan; Kirchner, James

    2016-04-01

    Despite many efforts to develop evapotranspiration models (in the framework of the Penman-Monteith equation) with improved parametrizations of various resistance terms to water vapor transfer into the atmosphere, evidence suggests that estimates of evapotranspiration and its partitioning are prone to bias. Much of this bias could arise from the exclusion of surface hydro-thermal properties and of physical interactions close to the surface where heat and water vapor fluxes originate. Recent progress has been made in mechanistic modeling of surface-turbulence interactions, accounting for localized heat and mass exchange rates from bare soil surfaces covered by protruding obstacles. We seek to extend these results partially vegetated surfaces, to improve predictive capabilities and accuracy of remote sensing techniques quantifying evapotranspiration fluxes. The governing equations of liquid water, water vapor, and energy transport dynamics in the soil-plant-atmosphere system are coupled to resolve diffusive vapor fluxes from isolated pores (plant stomata and soil pores) across a near-surface viscous sublayer, explicitly accounting for pore-scale transport mechanisms and environmental forcing. Preliminary results suggest that this approach offers unique opportunities for directly linking transport properties in plants and adjacent bare soil with resulting plant transpiration and localized bare soil evaporation rates. It thus provides an essential building block for interpreting and upscaling results to field and landscape scales for a range of vegetation cover and atmospheric conditions.

  8. DMSP SSM/T-2 microwave water vapor profiler

    Science.gov (United States)

    Galin, Israel; Brest, Dennis H.; Martner, Glen R.

    1993-08-01

    The Special Sensor Microwave water vapor profiler (SSM/T-2) is a five channel passive microwave sensor that operates in the 90 - 190 GHz frequency band. The instrument was developed by Aerojet Electronic Systems Division (AESD) of GenCorp Aerojet under a contract to the Defense Meteorological Satellite Program (DMSP). The first in a series of these instruments was successfully orbited in November 1991. This paper addresses details of the instrument configuration, as well as relevant information on the status of the project. A block diagram of the instrument is described in relation to its electrical, environmental and reliability requirements. Performance data measured in laboratory conditions is presented along with data from the operating unit in orbit.

  9. Formation and survival of water vapor in the terrestrial planet-forming region.

    Science.gov (United States)

    Bethell, Thomas; Bergin, Edwin

    2009-12-18

    Recent astronomical observations have revealed what may prove to be the ubiquity of water vapor during the early stages of planet formation. We present here a simple mechanism showing how water vapor forms in situ and is capable of shielding itself from molecule-destroying stellar radiation. The absorption of this radiation by water can control the thermodynamics of the terrestrial planet-forming zone. Similar to Earth's ozone layer, which shelters the chemistry of life, the water layer protects other water molecules and allows for a rich organic chemistry. The total abundance of water vapor in the natal habitable zone is equal to that of several thousand oceans.

  10. Search for water vapor in the high-resolution transmission spectrum of HD 189733b in the visible

    Science.gov (United States)

    Allart, R.; Lovis, C.; Pino, L.; Wyttenbach, A.; Ehrenreich, D.; Pepe, F.

    2017-10-01

    Context. Ground-based telescopes equipped with state-of-the-art spectrographs are able to obtain high-resolution transmission and emission spectra of exoplanets that probe the structure and composition of their atmospheres. Various atomic and molecular species, such as Na, CO, H2O have been already detected in a number of hot Jupiters. Molecular species have been observed only in the near-infrared while atomic species have been observed in the visible. In particular, the detection and abundance determination of water vapor bring important constraints to the planet formation process. Aims: We aim to search for water vapor in the atmosphere of the exoplanet HD 189733b using a high-resolution transmission spectrum in the visible obtained with HARPS. Methods: We used the atmospheric transmission code Molecfit to correct for telluric absorption features. Then we computed the high-resolution transmission spectrum of the planet using three transit datasets. We finally searched for water vapor absorption in the water band around 6500 Å using a cross-correlation technique that combines the signal of 600-900 individual lines. Results: Telluric features are corrected to the noise level. We place a 5-σ upper limit of 100 ppm on the strength of the 6500 Å water vapor band. The 1-σ precision of 20 ppm on the transmission spectrum demonstrates that space-like sensitivity can be achieved from the ground, even for a molecule that is a strong telluric absorber. Conclusions: This approach opens new possibilites for the detection of various atomic and molecular species with future instruments such as ESPRESSO at the VLT. Extrapolating from our results, we show that only one transit with ESPRESSO would be sufficient to detect water vapor on HD 189733b-like hot Jupiter with a cloud-free atmosphere. Upcoming near-IR spectrographs will be even more efficient and sensitive to a wider range of molecular species. Moreover, the detection of the same molecular species in different bands (e

  11. Enhanced Positive Water Vapor Feedback Associated with Tropical Deep Convection: New Evidence from Aura MLS

    Science.gov (United States)

    Su, Hui; Read, William G.; Jiang, Jonathan H.; Waters, Joe W.; Wu, Dong L.; Fetzer, Eric J.

    2006-01-01

    Recent simultaneous observations of upper tropospheric (UT) water vapor and cloud ice from the Microwave Limb Sounder (MLS) on the Aura satellite provide new evidence for tropical convective influence on UT water vapor and its associated greenhouse effect. The observations show that UT water vapor increases as cloud ice water content increases. They also show that, when sea surface temperature (SST) exceeds approx.300 K, UT cloud ice associated with tropical deep convection increases sharply with increasing SST. The moistening of the upper troposphere by deep convection leads to an enhanced positive water vapor feedback, about 3 times that implied solely by thermodynamics. Over tropical oceans when SST greater than approx.300 K, the 'convective UT water vapor feedback' inferred from the MLS observations contributes approximately 65% of the sensitivity of the clear-sky greenhouse parameter to SST.

  12. Retrieving Precipitable Water Vapor Data Using GPS Zenith Delays and Global Reanalysis Data in China

    Directory of Open Access Journals (Sweden)

    Peng Jiang

    2016-05-01

    Full Text Available GPS has become a very effective tool to remotely sense precipitable water vapor (PWV information, which is important for weather forecasting and nowcasting. The number of geodetic GNSS stations set up in China has substantially increased over the last few decades. However, GPS PWV derivation requires surface pressure to calculate the precise zenith hydrostatic delay and weighted mean temperature to map the zenith wet delay to precipitable water vapor. GPS stations without collocated meteorological sensors can retrieve water vapor using standard atmosphere parameters, which lead to a decrease in accuracy. In this paper, a method of interpolating NWP reanalysis data to site locations for generating corresponding meteorological elements is explored over China. The NCEP FNL dataset provided by the NCEP (National Centers for Environmental Prediction and over 600 observed stations from different sources was selected to assess the quality of the results. A one-year experiment was performed in our study. The types of stations selected include meteorological sites, GPS stations, radio sounding stations, and a sun photometer station. Compared with real surface measurements, the accuracy of the interpolated surface pressure and air temperature both meet the requirements of GPS PWV derivation in most areas; however, the interpolated surface air temperature exhibits lower precision than the interpolated surface pressure. At more than 96% of selected stations, PWV differences caused by the differences between the interpolation results and real measurements were less than 1.0 mm. Our study also indicates that relief amplitude exerts great influence on the accuracy of the interpolation approach. Unsatisfactory interpolation results always occurred in areas of strong relief. GPS PWV data generated from interpolated meteorological parameters are consistent with other PWV products (radio soundings, the NWP reanalysis dataset, and sun photometer PWV data. The

  13. Comparison of GNSS integrated water vapor and NWM reanalysis data over Central and South America

    Science.gov (United States)

    Fernandez, Laura Isabel; Mendoza, Luciano Pedro Oscar; Natali, María Paula; Meza, Amalia Margarita; Bianchi, Clara Eugenia

    2017-04-01

    Integrated water vapor (IWV) derived from Global Navigation Satellite Systems (GNSS) and Numerical Weather Models (NWM) reanalysis data were compared in order to assess the consistency between the different datasets over the extended geographical region of Central and South America. The investigation was performed for the seven-year period between 2007 and 2013. We analyzed two different reanalysis: the European Centre for Medium-Range Weather Forecast (ECMWF) reanalysis data (ERA Interim) and the Modern-Era Retrospective analysis for Research and Applications (MERRA2) from the National Aeronautics and Space Administration (NASA). The statistical analysis of the differences was performed in 110 GNSS sites (GPS +GLONASS), although the most interesting results came from the 73 sites which have more than 5 years of data. The study of the spatial distribution of the differences in the selected area involves different climate types, from polar to tropical, and it is characterized by large temporal variability of the integrated total humidity content. The inter-comparison was also performed on several time scales: from hours to years. In this study, not only the IWV values given by the different reanalysis where compared with the respective GNSS derived values but also the numeric integral of the IWV. This is nothing but the total vertically integrated water vapor of a unit air column each station but considering its real geopotential height. To that end, multilevel data from each reanalysis was also used. Moreover, the scarce coverage of operational radio sounding stations is noticeable in large areas of the selected region. Hence the contribution of IWV-GNSS is essential to improve the weather understanding. Considering that the atmospheric water vapor has a highly variable and complex distribution which knowledge is essential for weather prediction and local meteorological studies, this study aims to provide IWV-GNSS observations able to be assimilated by operational

  14. Water and water vapor sorption studies in polypropylene-zeolite composites

    OpenAIRE

    Pehlivan, H.; Özmıhçı, Filiz; Tıhmınlıoğlu, Funda; Balköse, Devrim; Ülkü, Semra

    2003-01-01

    Water and water vapor sorption to porous polypropylene-zeolite composites prepared by hot pressing have been studied as a function of zeolite loading. This work presents the first report on the effect of the zeolite as a filler on the water-sorption properties of PP composites. Water swelling experiments were conducted at 25°C using pure PP and PP-zeolite films samples having different zeolite loadings (6-40 wt %). Because PP is a hydrophobic polymer, it does not sorp any water, but the compo...

  15. Kinetic Requirements for the Measurement of Mesospheric Water Vapor at 6.8 (microns) under Non-LTE Conditions

    Science.gov (United States)

    Zhou, Daniel K.; Mlynczak, Martin G.; Lopez-Puertas, Manuel; Russell, James M., III

    1999-01-01

    We present accuracy requirements for specific kinetic parameters used to calculate the populations and vibrational temperatures of the H2O(010) and H2O(020) states in the terrestrial mesosphere. The requirements are based on rigorous simulations of the retrieval of mesospheric water vapor profiles from measurements of water vapor infrared emission made by limb scanning instruments on orbiting satellites. Major improvements in the rate constants that describe vibration-to- vibration exchange between the H2O(010) and 02(1) states are required in addition to improved specification of the rate of quenching Of O2(1) by atomic oxygen (0). It is also necessary to more accurately determine the yield of vibrationally excited O2(l) resulting from ozone photolysis. A contemporary measurement of the rate of quenching of H2O(010) by N2 and O2 is also desirable. These rates are either highly uncertain or have never before been measured at atmospheric temperatures. The suggested improvements are necessary for the interpretation of water vapor emission measurements at 6.8 microns to be made from a new spaceflight experiment in less than 2 years. The approach to retrieving water vapor under non-LTE conditions is also presented.

  16. A quartz-enhanced photoacoustic spectroscopy sensor for measurement of water vapor concentration in the air

    Science.gov (United States)

    Gong, Ping; Xie, Liang; Qi, Xiao-Qiong; Wang, Rui; Wang, Hui; Chang, Ming-Chao; Yang, Hui-Xia; Sun, Fei; Li, Guan-Peng

    2015-01-01

    A compact and highly linear quartz-enhanced photoacoustic spectroscopy (QEPAS) sensor for the measurement of water vapor concentration in the air is demonstrated. A cost-effective quartz tuning fork (QTF) is used as the sharp transducer to convert light energy into an electrical signal based on the piezoelectric effect, thereby removing the need for a photodetector. The short optical path featured by the proposed sensing system leads to a decreased size. Furthermore, a pair of microresonators is applied in the absorbance detection module (ADM) for QTF signal enhancement. Compared with the system without microresonators, the detected QTF signal is increased to approximately 7-fold. Using this optimized QEPAS sensor with the proper modulation frequency and depth, we measure the water vapor concentration in the air at atmospheric pressure and room temperature. The experimental result shows that the sensor has a high sensitivity of 1.058 parts-per-million. Project supported by the National Natural Science Foundation of China (Grant Nos. 61107070, 61127018, and 61377071).

  17. Growth of atmospheric nano-particles by heterogeneous nucleation of organic vapor

    Science.gov (United States)

    Wang, J.; McGraw, R. L.; Kuang, C.

    2013-07-01

    Atmospheric aerosols play critical roles in air quality, public health, and visibility. In addition, they strongly influence climate by scattering solar radiation and by changing the reflectivity and lifetime of clouds. One major but still poorly understood source of atmospheric aerosols is new particle formation, which consists of the formation of thermodynamically stable clusters from trace gas molecules (homogeneous nucleation) followed by growth of these clusters to a detectable size (~3 nm). Because freshly nucleated clusters are most susceptible to loss due to high rate of coagulation with pre-existing aerosol population, the initial growth rate strongly influences the rate of new particle formation and ambient aerosol population. Whereas many field observations and modeling studies indicate that organics enhance the initial growth of the clusters and therefore new particle formation, thermodynamic considerations would suggest that the strong increase of equilibrium vapor concentration due to cluster surface curvature (Kelvin effect) may prevent ambient organics from condensing on these small clusters. Here, the contribution of organics to the initial cluster growth is described as heterogeneous nucleation of organic molecules onto these clusters. We find that the strong gradient in cluster population with respect to its size leads to positive cluster number flux. This positive flux drives the growth of clusters substantially smaller than the Kelvin diameter, conventionally considered the minimum particle size that can be grown through condensation. The conventional approach neglects the contribution from the cluster concentration gradient, and underestimates the cluster survival probabilities by a factor of up to 60 if early growth of clusters is due to both condensation of sulfuric acid and heterogeneous nucleation of organic vapors.

  18. MODIS/Aqua Granule Level 2 Water Vapor Near Infrared Jpeg image

    Data.gov (United States)

    National Aeronautics and Space Administration — This is a Jpeg image product generated from MODIS Level 2 Precipitable Water product (MYD05_L2) using WATER_VAPOR_NEAR_INFRARED parameter. For more information about...

  19. MODIS/Terra Granule Level 2 Water Vapor Near Infrared Jpeg image

    Data.gov (United States)

    National Aeronautics and Space Administration — This is a Jpeg image product generated from MODIS Level 2 Precipitable Water product (MOD05_L2) using WATER_VAPOR_NEAR_INFRARED parameter. For more information about...

  20. SAFARI 2000 MODIS MOD05_L2 Water Vapor Data, Binary Format, for Southern Africa

    Data.gov (United States)

    National Aeronautics and Space Administration — The MODIS precipitable water product consists of vertical column water-vapor amounts in centimeters (cm) at 1 km spatial resolution. The SAFARI 2000 product,...

  1. Isobaric vapor-liquid equilibria for methanol + ethanol + water and the three constituent binary systems

    Energy Technology Data Exchange (ETDEWEB)

    Kurihara, Kiyofumi; Nakamichi, Mikiyoshi; Kojima, Kazuo (Nihon Univ., Tokyo (Japan). Dept. of Industrial Chemistry)

    1993-07-01

    Vapor-liquid equilibrium data for methanol + ethanol + water and its three constituent binary systems methanol + ethanol, ethanol + water, and methanol + water were measured at 101.3 kPa using a liquid-vapor ebullition-type equilibrium still. The experimental binary data were correlated by the NRTL equation. The ternary system methanol + ethanol + water was predicted by means of the binary NRTL parameters with good accuracy.

  2. An insight into the western Pacific wintertime moisture sources using dual water vapor isotopes

    Science.gov (United States)

    Rangarajan, Ravi; Laskar, Amzad H.; Bhattacharya, Sourendra K.; Shen, Chuan-Chou; Liang, Mao-Chang

    2017-04-01

    Continuous measurements of isotopic ratios in atmospheric water vapor in a western Pacific region (Taipei, Taiwan) in two winters (2011 and 2012) were made and analyzed to understand the moisture source characteristics. In wintertime, the so-called East Asian Monsoon dominates, largely affecting the climate and meteorology of this region. Being located in the subtropical region, Taipei provides an ideal opportunity for studying interactions between high latitude cold and dry continental air masses and low to mid-latitude warm and wet oceanic air. Indeed, the dual isotope function, d-excess shows the presence of two distinct moisture sources, contributing to the winter vapor isotope variability. Undoubtedly, the dominant moisture source is the high latitude continental cold air masses reaching Taipei with d-excess values of >20‰. Alongside, wet and warm air masses characterized by strong air-sea interaction from the surrounding oceans, possessing d-excess value of ∼10‰ also play a role. The interactions of these two distinct air masses cause the d-excess values to change by as much as ∼20‰ in a few days. Multiple regression analysis shows that source moisture composition and water vapor mixing ratio combined control over 60% of the observed variability. We developed a box model to show that both high and low d-excess events in the winter are primarily controlled by the humidity deficit over the ocean. The information obtained in this study could be used in interpreting the paleoclimate proxies within the East Asian region.

  3. Polybenzimidazole-based mixed membranes with exceptional high water vapor permeability and selectivity

    KAUST Repository

    Akhtar, Faheem Hassan

    2017-09-13

    Polybenzimidazole (PBI), a thermal and chemically stable polymer, is commonly used to fabricate membranes for applications like hydrogen recovery at temperatures of more than 300 °C, fuel cells working in a highly acidic environment, and nanofiltration in aggressive solvents. This report shows for the first time use of PBI dense membranes for water vapor/gas separation applications. They showed an excellent selectivity and high water vapor permeability. Incorporation of inorganic hydrophilic titanium-based nano-fillers into the PBI matrix further increased the water vapor permeability and water vapor/N2 selectivity. The most selective mixed matrix membrane with 0.5 wt% loading of TiO2 nanotubes yielded a water vapor permeability of 6.8×104 Barrer and a H2O/N2 selectivity of 3.9×106. The most permeable membrane with 1 wt% loading of carboxylated TiO2 nanoparticles had a 7.1×104 Barrer water vapor permeability and a H2O/N2 selectivity of 3.1×106. The performance of these membranes in terms of water vapor transport and selectivity is among the highest reported ones. The remarkable ability of PBI to efficiently permeate water versus other gases opens the possibility to fabricate membranes for dehumidification of streams in harsh environments. This includes the removal of water from high temperature reaction mixtures to shift the equilibrium towards products.

  4. Material gap membrane distillation: A new design for water vapor flux enhancement

    KAUST Repository

    Francis, Lijo

    2013-08-19

    A new module design for membrane distillation, namely material gap membrane distillation (MGMD), for seawater desalination has been proposed and successfully tested. It has been observed that employing appropriate materials between the membrane and the condensation plate in an air gap membrane distillation (AGMD) module enhanced the water vapor flux significantly. An increase in the water vapor flux of about 200-800% was observed by filling the gap with sand and DI water at various feed water temperatures. However, insulating materials such as polypropylene and polyurethane have no effect on the water vapor flux. The influence of material thickness and characteristics has also been investigated in this study. An increase in the water gap width from 9. mm to 13. mm increases the water vapor flux. An investigation on an AGMD and MGMD performance comparison, carried out using two different commercial membranes provided by different manufacturers, is also reported in this paper. © 2013 Elsevier B.V.

  5. Remote sensing of seasonal distribution of precipitable water vapor over the oceans and the inference of boundary-layer structure

    Science.gov (United States)

    Prabhakara, C.; Lo, R. C.; Nath, N. R.; Dalu, G.

    1979-01-01

    From the depth of the water vapor spectral lines in the 8-9 micron window region, measured by the Nimbus 4 Infrared Interferometer Spectrometer (IRIS) with a resolution of about 3/cm, the precipitable water vapor over the oceans is remotely sensed. In addition the IRIS spectral data in the 11-13 micron window region have been used to derive the sea surface temperature (SST). Seasonal maps of w on the oceans deduced from the spectral data reveal the dynamical influence of the large-scale atmospheric circulation. With the help of a model for the vertical distribution of water vapor, the configuration of the atmospheric boundary layer over the oceans can be inferred from these remotely sensed w and SST. The gross seasonal mean structure of the boundary layer inferred in this fashion reveals the broad areas of trade wind inversion and the convectively active areas such as the ITCZ. The derived information is in reasonable agreement with some observed climatological patterns over the oceans.

  6. Feasibility of retrieving dust properties and total column water vapor from solar spectra measured using a lander camera on Mars

    Science.gov (United States)

    Manago, Naohiro; Noguchi, Katsuyuki; Hashimoto, George L.; Senshu, Hiroki; Otobe, Naohito; Suzuki, Makoto; Kuze, Hiroaki

    2017-12-01

    Dust and water vapor are important constituents in the Martian atmosphere, exerting significant influence on the heat balance of the atmosphere and surface. We have developed a method to retrieve optical and physical properties of Martian dust from spectral intensities of direct and scattered solar radiation to be measured using a multi-wavelength environmental camera onboard a Mars lander. Martian dust is assumed to be composed of silicate-like substrate and hematite-like inclusion, having spheroidal shape with a monomodal gamma size distribution. Error analysis based on simulated data reveals that appropriate combinations of three bands centered at 450, 550, and 675 nm wavelengths and 4 scattering angles of 3°, 10°, 50°, and 120° lead to good retrieval of four dust parameters, namely, aerosol optical depth, effective radius and variance of size distribution, and volume mixing ratio of hematite. Retrieval error increases when some of the observational parameters such as color ratio or aureole are omitted from the retrieval. Also, the capability of retrieving total column water vapor is examined through observations of direct and scattered solar radiation intensities at 925, 935, and 972 nm. The simulation and error analysis presented here will be useful for designing an environmental camera that can elucidate the dust and water vapor properties in a future Mars lander mission.

  7. An environmental sample chamber for reliable scanning transmission x-ray microscopy measurements under water vapor

    Energy Technology Data Exchange (ETDEWEB)

    Kelly, Stephen T.; Nigge, P.; Prakash, Shruti; Laskin, Alexander; Wang, Bingbing; Tyliszczak, Tolek; Leone, Stephen R.; Gilles, Mary K.

    2013-08-01

    We have designed, fabricated, and tested a compact gas-phase reactor for performing in situ soft x-ray scanning transmission x-ray microscopy (STXM) measurements. The reactor accommodates many gas atmospheres, including reactive or corrosive gasses, but was designed specically to address the needs of measurements under water vapor. An on-board sensor measures the relative humidity and temperature inside the reactor, minimizing uncertainties associated with measuring these quantities outside the instrument. The reactor mounts directly to the existing sample holder used in the majority of STXM instruments around the world and installs with minimal instrument reconguration. Using the reactor contributes over 85% less additional absorption compared to lling the STXM chamber with process gas, and results in much more stable imaging conditions. The reactor is in use at the STXM instruments at beamlines 11.0.2 and 5.3.2.2 at the Advanced Light Source.

  8. Major Upgrades to the AIRS Version-6 Water Vapor Profile Methodology

    Science.gov (United States)

    Susskind, Joel; Blaisdell, John; Iredell, Lena; Lee, Jae N.

    2015-01-01

    Additional changes in Version-6.19 include all previous updates made to the q(p) retrieval since Version-6: Modified Neural-Net q0(p) guess above the tropopause Linearly tapers the neural net guess to match climatology at 70 mb, not at the top of the atmosphereChanged the 11 trapezoid q(p) perturbation functions used in Version-6 so as to match the 24 functions used in T(p) retrieval step. These modifications resulted in improved water vapor profiles in Version-6.19 compared to Version-6.Version-6.19 is tested for all of August 2013 and August 2014, as well for select other days. Before finalized and operational in 2016, the V-6.19 can be acquired upon request for limited time intervals.

  9. Effect of Water Vapor During Secondary Cooling on Hot Shortness in Fe-Cu-Ni-Sn-Si Alloys

    Science.gov (United States)

    Sampson, Erica; Sridhar, Seetharaman

    2014-10-01

    Residual Cu in recycled steel scrap can cause hot shortness when the iron matrix is oxidized. Hot shortness can occur directly after the solid steel is formed from continuous casting as the steel undergoes a cooling process known as secondary cooling where water is first sprayed on the surface to promote cooling. This is followed by a radiant cooling stage where the steel is cooled in air to room temperature. This investigation examines the roles of water vapor, Si content, temperature, and the presence of Sn in a Fe-0.2 wt pct Cu-0.05 wt pct Ni alloy on oxidation, separated Cu and Cu induced-hot shortness during simulations of the secondary cooling process. The secondary cooling from 1473 K (1200 °C) resulted in a slight increase in liquid quantity and grain boundary penetration as compared to the isothermal heating cycles at 1423 K (1150 °C) due to the higher temperatures experienced in the non-isothermal cycle. The addition of water vapor increased the sample oxidation as compared to samples processed in dry atmospheres due to increased scale adherence, scale plasticity, and inward transport of oxygen. The increase in weight gain of the wet atmosphere increased the liquid formation at the interface in the non-Si containing alloys. The secondary cooling cycle with water vapor and the effect of Sn lead to the formation of many small pools of Cu-rich liquid embedded within the surface of the metal due to the Sn allowing for increased grain boundary decohesion and the water vapor allowing for oxidation within liquid-penetrated grain boundaries. The presence of Si increased the amount of occlusion of Cu and Fe, significantly decreasing the quantity of liquid at the interface and the amount of grain boundary penetration.

  10. Modeling Convective Injection of Water Vapor into the Lower Stratosphere in the Mid-Latitudes over North America

    Science.gov (United States)

    Clapp, C.; Leroy, S. S.; Anderson, J. G.

    2015-12-01

    Water vapor in the upper troposphere and lower stratosphere (UTLS) from the tropics to the poles is important both radiatively and chemically. Water vapor is the most important greenhouse gas, and increases in water vapor concentrations in the UTLS lead to cooling at these levels and induce warming at the surface [Forster and Shine, 1999; 2002;Solomon et al., 2010]. Water vapor is also integral to stratospheric chemistry. It is the dominant source of OH in the lower stratosphere [ Hanisco et al. , 2001], and increases in water vapor concentrations promote stratospheric ozone loss by raising the reactivity of several key heterogeneous reactions as well as by promoting the growth of reactive surface area [Anderson et al., 2012; Carslaw et al., 1995; Carslaw et al., 1997; Drdla and Muller , 2012; Kirk-Davidoff et al., 1999; Shi et al., 2001]. However, the processes that control the distribution and phase of water in this region of the atmosphere are not well understood. This is especially true at mid-latitudes where several different dynamical mechanisms are capable of influencing UTLS water vapor concentrations. The contribution by deep convective storm systems that penetrate into the lower stratosphere is the least well understood and the least well represented in global models because of the small spatial scales and short time scales over which convection occurs. To address this issue, we have begun a modeling study to investigate the convective injection of water vapor from the troposphere into the stratosphere in the mid-latitudes. Fine-scale models have been previously used to simulate convection from the troposphere to the stratosphere [e.g., Homeyer et al., 2014]. Here we employ the Advanced Research Weather and Research Forecasting model (ARW) at 3-km resolution to resolve convection over the eastern United States during August of 2007 and August of 2013. We conduct a comparison of MERRA, the reanalysis used to initialize ARW, and the model output to assess

  11. Antimicrobial effects of vapor phase thymol, modified atmosphere and their combination against Salmonella spp. on raw shrimp

    Science.gov (United States)

    Salmonella contamination of raw shrimp is a food safety concern in the U.S. and other countries. This research evaluated the effects of vapor phase thymol, modified atmosphere (MA) and their combination against Salmonella spp. on raw shrimp. Growth profiles of a Salmonella spp. cocktail (6 strains),...

  12. Catalytic combustion of styrene over copper based catalyst: inhibitory effect of water vapor.

    Science.gov (United States)

    Pan, Hongyan; Xu, Mingyao; Li, Zhong; Huang, Sisi; He, Chun

    2009-07-01

    The effects of water vapor on the activity of the copper based catalysts with different supports such as CuO/gamma-Al2O3, CuO/SiO2 and CuO/TiO2 for styrene combustion were investigated. The catalytic activity of the catalysts was tested in the absence of and presence of water vapor and the catalysts were characterized. Temperature programmed desorption (TPD) experiments and diffuse reflectance infrared fourier transform spectroscopy (DRIFTS) measurements were conducted in order to estimate and explain the water effects. Results showed that the existence of water vapor had a significant negative effect on the catalytic activity of these copper based catalysts due to the competition adsorption of water molecule. DRIFTS studies showed that the catalyst CuO/gamma-Al2O3 had the strongest adsorption of water, while the catalyst CuO/TiO2 had the weakest adsorption of water. H2O-TPD studies also indicated that the order of desorption activation energies of water vapor on the catalysts or the strength of interactions of water molecules with the surfaces of the catalysts was CuO/gamma-Al2O3>CuO/SiO2>CuO/TiO2. As a consequence of that, the CuO/TiO2 exhibited the better durability to water vapor, while CuO/gamma-Al2O3 had the poorest durability to water vapor among these three catalysts.

  13. Two decades of water vapor measurements with the FISH fluorescence hygrometer: a review

    Directory of Open Access Journals (Sweden)

    J. Meyer

    2015-07-01

    Full Text Available For almost two decades, the airborne Fast In-situ Stratospheric Hygrometer (FISH has stood for accurate and precise measurements of total water mixing ratios (WMR, gas phase + evaporated ice in the upper troposphere and lower stratosphere (UT/LS. Here, we present a comprehensive review of the measurement technique (Lyman-α photofragment fluorescence, calibration procedure, accuracy and reliability of FISH. Crucial for FISH measurement quality is the regular calibration to a water vapor reference, namely the commercial frost-point hygrometer DP30. In the frame of this work this frost-point hygrometer is compared to German and British traceable metrological water standards and its accuracy is found to be 2–4 %. Overall, in the range from 4 to 1000 ppmv, the total accuracy of FISH was found to be 6–8 %, as stated in previous publications. For lower mixing ratios down to 1 ppmv, the uncertainty reaches a lower limit of 0.3 ppmv. For specific, non-atmospheric conditions, as set in experiments at the AIDA chamber – namely mixing ratios below 10 and above 100 ppmv in combination with high- and low-pressure conditions – the need to apply a modified FISH calibration evaluation has been identified. The new evaluation improves the agreement of FISH with other hygrometers to ± 10 % accuracy in the respective mixing ratio ranges. Furthermore, a quality check procedure for high total water measurements in cirrus clouds at high pressures (400–500 hPa is introduced. The performance of FISH in the field is assessed by reviewing intercomparisons of FISH water vapor data with other in situ and remote sensing hygrometers over the last two decades. We find that the agreement of FISH with the other hygrometers has improved over that time span from overall up to ± 30 % or more to about ± 5–20 % @ 10 ppmv. As presented here, the robust and continuous calibration and operation procedures of the FISH instrument over the last two decades establish the

  14. Water vapor adsorption isotherms of agar-based nanocomposite films.

    Science.gov (United States)

    Rhim, Jong-Whan

    2011-10-01

    Adsorption isotherms of agar and agar/clay nanocomposite films prepared with different types of nanoclays, that is, a natural montmorillonite (Cloisite Na(+) ) and 2 organically modified montmorillonites (Cloisite 30B and Cloisite 20A), were determined at 3 different temperatures (10, 25, and 40 °C). The water vapor adsorption behavior of the nanocomposite films was found to be greatly influenced with the type of clay. The Guggenheim-Anderson-de Boer (GAB) isotherm model parameters were estimated by using both polynomial regression and nonlinear regression methods and it was found that the GAB model fitted adequately for describing experimental adsorption isotherm data for the film samples. The monolayer moisture content (m(o) ) of the film samples was also greatly affected by the type of nanoclay used, that is, m(o) of nanocomposite films was significantly lower than that of the neat agar film. Nanocomposite films prepared with hydrophobic nanoclays (Cloisite 30B and Cloisite 20A) exhibited lower m(o) values than those prepared with hydrophilic nanoclay (Cloisite Na(+) ). © 2011 Institute of Food Technologists®

  15. Precipitable Water Vapor Estimates in the Australian Region from Ground-Based GPS Observations

    Directory of Open Access Journals (Sweden)

    Suelynn Choy

    2015-01-01

    Full Text Available We present a comparison of atmospheric precipitable water vapor (PWV derived from ground-based global positioning system (GPS receiver with traditional radiosonde measurement and very long baseline interferometry (VLBI technique for a five-year period (2008–2012 using Australian GPS stations. These stations were selectively chosen to provide a representative regional distribution of sites while ensuring conventional meteorological observations were available. Good agreement of PWV estimates was found between GPS and VLBI comparison with a mean difference of less than 1 mm and standard deviation of 3.5 mm and a mean difference and standard deviation of 0.1 mm and 4.0 mm, respectively, between GPS and radiosonde measurements. Systematic errors have also been discovered during the course of this study, which highlights the benefit of using GPS as a supplementary atmospheric PWV sensor and calibration system. The selected eight GPS sites sample different climates across Australia covering an area of approximately 30° NS/EW. It has also shown that the magnitude and variation of PWV estimates depend on the amount of moisture in the atmosphere, which is a function of season, topography, and other regional climate conditions.

  16. Water vapor in the spectrum of the extrasolar planet HD 189733b. II. The eclipse

    Energy Technology Data Exchange (ETDEWEB)

    Crouzet, Nicolas [Dunlap Institute for Astronomy and Astrophysics, University of Toronto, 50 St. George Street, Toronto, Ontario M5S 3H4 (Canada); McCullough, Peter R. [Space Telescope Science Institute, Baltimore, MD 21218 (United States); Deming, Drake [Department of Astronomy, University of Maryland, College Park, MD 20742 (United States); Madhusudhan, Nikku, E-mail: crouzet@dunlap.utoronto.ca [Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA (United Kingdom)

    2014-11-10

    Spectroscopic observations of exoplanets are crucial to infer the composition and properties of their atmospheres. HD 189733b is one of the most extensively studied exoplanets and is a cornerstone for hot Jupiter models. In this paper, we report the dayside emission spectrum of HD 189733b in the wavelength range 1.1-1.7 μm obtained with the Hubble Space Telescope Wide Field Camera 3 (WFC3) in spatial scan mode. The quality of the data is such that even a straightforward analysis yields a high-precision Poisson noise-limited spectrum: the median 1σ uncertainty is 57 ppm per 0.02 μm bin. We also build a white-light curve correcting for systematic effects and derive an absolute eclipse depth of 96 ± 39 ppm. The resulting spectrum shows marginal evidence for water vapor absorption, but can also be well explained by a blackbody spectrum. However, the combination of these WFC3 data with previous Spitzer photometric observations is best explained by a dayside atmosphere of HD 189733b with no thermal inversion and a nearly solar or subsolar H{sub 2}O abundance in a cloud-free atmosphere. Alternatively, this apparent subsolar abundance may be the result of clouds or hazes that future studies need to investigate.

  17. In situ separation of root hydraulic redistribution of soil water from liquid and vapor transport

    Science.gov (United States)

    Jeffrey M. Warren; J. Renée Brooks; Maria I. Dragila; Frederick C. Meinzer

    2011-01-01

    Nocturnal increases in water potential and water content in the upper soil profile are often attributed to root water efflux, a process termed hydraulic redistribution (HR). However, unsaturated liquid or vapor flux of water between soil layers independent of roots also contributes to the daily recovery in water content, confounding efforts to determine the actual...

  18. Final Scientific/Technical Report. A closed path methane and water vapor gas analyzer

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Liukang [LI-COR Inc., Lincoln, NE (United States); McDermitt, Dayle [LI-COR Inc., Lincoln, NE (United States); Anderson, Tyler [LI-COR Inc., Lincoln, NE (United States); Riensche, Brad [LI-COR Inc., Lincoln, NE (United States); Komissarov, Anatoly [LI-COR Inc., Lincoln, NE (United States); Howe, Julie [LI-COR Inc., Lincoln, NE (United States)

    2012-02-01

    Robust, economical, low-power and reliable closed-path methane (CH4), carbon dioxide (CO2), and water vapor (H2O) analyzers suitable for long-term measurements are not readily available commercially. Such analyzers are essential for quantifying the amount of CH4 and CO2 released from various ecosystems (wetlands, rice paddies, forests, etc.) and other surface contexts (e.g. landfills, animal husbandry lots, etc.), and for understanding the dynamics of the atmospheric CH4 and CO2 budget and their impact on climate change and global warming. The purpose of this project is to develop a closed-path methane, carbon dioxide gas and water vapor analyzer capable of long-term measurements in remote areas for global climate change and environmental research. The analyzer will be capable of being deployed over a wide range of ecosystems to understand methane and carbon dioxide exchange between the atmosphere and the surface. Measurements of methane and carbon dioxide exchange need to be made all year-round with limited maintenance requirements. During this Phase II effort, we successfully completed the design of the electronics, optical bench, trace gas detection method and mechanical infrastructure. We are using the technologies of two vertical cavity surface emitting lasers, a multiple-pass Herriott optical cell, wavelength modulation spectroscopy and direct absorption to measure methane, carbon dioxide, and water vapor. We also have designed the instrument application software, Field Programmable Gate Array (FPGA), along with partial completion of the embedded software. The optical bench has been tested in a lab setting with very good results. Major sources of optical noise have been identified and through design, the optical noise floor is approaching -60dB. Both laser modules can be temperature controlled to help maximize the stability of the analyzer. Additionally, a piezo electric transducer has been

  19. How do atmospheric rivers form?

    Science.gov (United States)

    Dacre, Helen

    2015-04-01

    The term atmospheric river is used to describe corridors of strong water vapor transport in the troposphere. Filaments of enhanced water vapor, commonly observed in satellite imagery extending from the subtropics to the extratropics, are routinely used as a proxy for identifying these regions of strong water vapor transport. The precipitation associated with these filaments of enhanced water vapor can lead to high impact flooding events. However, there remains some debate as to how these filaments form. In this study we analyse the transport of water vapor within a climatology of wintertime North Atlantic extratropical cyclones. Results show that atmospheric rivers are formed by the cold front which sweeps up water vapor in the warm sector as it catches up with the warm front. This causes a narrow band of high water vapor content to form ahead of the cold front at the base of the warm conveyor belt airflow. Thus, water vapor in the cyclone's warm sector, and not long-distance transport of water vapor from the subtropics, is responsible for the generation of filaments of high water vapor content. A continuous cycle of evaporation and moisture convergence within the cyclone replenishes water vapor lost via precipitation. Thus, rather than representing a direct and continuous feed of moist air from the subtropics into the centre of a cyclone (as suggested by the term atmospheric river), these filaments are, in-fact, the result of water vapor exported from the cyclone and thus they represent the footprints left behind as cyclones travel polewards from subtropics.

  20. Experimental and Numerical Studies of Atmosphere Water Interactions

    KAUST Repository

    Bou-Zeid, Elie

    2011-07-04

    Understanding and quantifying the interaction of the atmosphere with underlying water surfaces is of great importance for a wide range of scientific fields such as water resources management, climate studies of ocean-atmosphere exchange, and regional weat

  1. Seasonal Trends in Stratospheric Water Vapor as Derived from SAGE II Data

    Science.gov (United States)

    Roell, Marilee M.; Fu, Rong

    2008-01-01

    Published analysis of HALOE and Boulder balloon measurements of water vapor have shown conflicting trends in stratospheric water vapor for the periods of 1981 through 2005. Analysis of the SAGE II monthly mean water vapor data filtered for large aerosol events for time periods from 1985-1991, 1995-1999, and 2000-2005 have shown a globally decreasing water vapor trend at 17.5km. Seasonal analysis for these three time periods show a decreasing trend in water vapor at 17.5km for the winter and spring seasons. The summer and autumn seasonal analysis show a decreasing trend from 1985-2005, however, there is a increasing trend in water vapor at 17.5km for these seasons during 1995-2005. Latitude vs height seasonal analysis show a decreasing trend in the lower stratosphere between 20S - 20N for the autumn season, while at the latitudes of 30-50S and 30-50N there is an increasing trend in water vapor at heights up to 15km for that season. Comparison with regions of monsoon activity (Asian and North American) show that the Asian monsoon region had some effect on the lower stratospheric moistening in 1995-1999, however, for the time period of 2000-2005, there was no change in the global trend analysis due to either monsoon region. This may be due to the limitations of the SAGE II data from 2000-2005.

  2. The Representation of Tropospheric Water Vapor Over Low-Latitude Oceans in (Re-)analysis: Errors, Impacts, and the Ability to Exploit Current and Prospective Observations

    Science.gov (United States)

    Pincus, Robert; Beljaars, Anton; Buehler, Stefan A.; Kirchengast, Gottfried; Ladstaedter, Florian; Whitaker, Jeffrey S.

    2017-10-01

    This paper addresses the representation of lower tropospheric water vapor in the meteorological analyses—fully detailed estimates of atmospheric state—providing the wide temporal and spatial coverage used in many process studies. Analyses are produced in a cycle combining short forecasts from initial conditions with data assimilation that optimally estimates the state of the atmosphere from the previous forecasts and new observations, providing initial conditions for the next set of forecasts. Estimates of water vapor are among the less certain aspects of the state because the quantity poses special challenges for data assimilation while being particularly sensitive to the details of model parameterizations. Over remote tropical oceans observations of water vapor come from two sources: passive observations at microwave or infrared wavelengths that provide relatively strong constraints over large areas on column-integrated moisture but relatively coarse vertical resolution, and occultations of Global Positioning System provide much higher accuracy and vertical resolution but are relatively spatially coarse. Over low-latitude oceans, experiences with two systems suggest that current analyses reproduce much of the large-scale variability in integrated water vapor but have systematic errors in the representation of the boundary layer with compensating errors in the free troposphere; these errors introduce errors of order 10% in radiative heating rates through the free troposphere. New observations, such as might be obtained by future observing systems, improve the estimates of water vapor but this improvement is lost relatively quickly, suggesting that exploiting better observations will require targeted improvements to global forecast models.

  3. NEAR-IR DIRECT DETECTION OF WATER VAPOR IN TAU BOÖTIS b

    Energy Technology Data Exchange (ETDEWEB)

    Lockwood, Alexandra C.; Johnson, John A.; Blake, Geoffrey A. [Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125 (United States); Bender, Chad F.; Richert, Alexander J. W. [Department of Astronomy and Astrophysics, Pennsylvania State University, University Park, PA 16802 (United States); Carr, John S. [Naval Research Laboratory, Washington, DC 20375 (United States); Barman, Travis, E-mail: alock@caltech.edu [Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ 85721 (United States)

    2014-03-10

    We use high dynamic range, high-resolution L-band spectroscopy to measure the radial velocity (RV) variations of the hot Jupiter in the τ Boötis planetary system. The detection of an exoplanet by the shift in the stellar spectrum alone provides a measure of the planet's minimum mass, with the true mass degenerate with the unknown orbital inclination. Treating the τ Boo system as a high flux ratio double-lined spectroscopic binary permits the direct measurement of the planet's true mass as well as its atmospheric properties. After removing telluric absorption and cross-correlating with a model planetary spectrum dominated by water opacity, we measure a 6σ detection of the planet at K{sub p} = 111 ± 5 km s{sup –1}, with a 1σ upper limit on the spectroscopic flux ratio of 10{sup –4}. This RV leads to a planetary orbital inclination of i=45{sub −4}{sup +3}° and a mass of M{sub P}=5.90{sub −0.20}{sup +0.35} M{sub Jup}. We report the first detection of water vapor in the atmosphere of a non-transiting hot Jupiter, τ Boo b.

  4. Water vapor mass balance method for determining air infiltration rates in houses

    Science.gov (United States)

    David R. DeWalle; Gordon M. Heisler

    1980-01-01

    A water vapor mass balance technique that includes the use of common humidity-control equipment can be used to determine average air infiltration rates in buildings. Only measurements of the humidity inside and outside the home, the mass of vapor exchanged by a humidifier/dehumidifier, and the volume of interior air space are needed. This method gives results that...

  5. H2O and CO2 vapor pressure measurements at temperatures relevant to the middle atmosphere of Earth and Mars

    Science.gov (United States)

    Nachbar, M.; Duft, D.; Leisner, T.

    2017-09-01

    Measurements of the vapor pressure of H2O and CO2 at temperatures relevant to the middle atmosphere of Earth and Mars are rare but important in order to describe cloud formation and ice particle growth processes. In this contribution we present a novel technique for measuring the vapor pressure of condensable gases by analyzing the depositional growth rates on free nanoparticles at high supersaturation. The method is applied to measure the vapor pressure of CO2 between 75K and 85K. By comparison with previous measurements and parameterizations we are able to show the excellent functionality of the method. In addition, the method is used to measure the vapor pressure over H2O ice between 135K and 160K. We show that the vapor pressure of so called stacking disordered ice Isd deposited at temperatures below 160K is significantly higher compared to hexagonal ice Ih. The consequences for ice cloud formation in the atmosphere of Earth and Mars will be discussed.

  6. Distribution of binding energies of a water molecule in the water liquid-vapor interface

    Energy Technology Data Exchange (ETDEWEB)

    Chempath, Shaji [Los Alamos National Laboratory; Pratt, Lawrence R [TULANE UNIV

    2008-01-01

    Distributions of binding energies of a water molecule in the water liquid-vapor interface are obtained on the basis of molecular simulation with the SPC/E model of water. These binding energies together with the observed interfacial density profile are used to test a minimally conditioned Gaussian quasi-chemical statistical thermodynamic theory. Binding energy distributions for water molecules in that interfacial region clearly exhibit a composite structure. A minimally conditioned Gaussian quasi-chemical model that is accurate for the free energy of bulk liquid water breaks down for water molecules in the liquid-vapor interfacial region. This breakdown is associated with the fact that this minimally conditioned Gaussian model would be inaccurate for the statistical thermodynamics of a dilute gas. Aggressive conditioning greatly improves the performance of that Gaussian quasi-chemical model. The analogy between the Gaussian quasi-chemical model and dielectric models of hydration free energies suggests that naive dielectric models without the conditioning features of quasi-chemical theory will be unreliable for these interfacial problems. Multi-Gaussian models that address the composite nature of the binding energy distributions observed in the interfacial region might provide a mechanism for correcting dielectric models for practical applications.

  7. Progress Toward an Autonomous Field Deployable Diode Laser Based Differential Absorption Lidar (DIAL) for Profiling Water Vapor in the Lower Troposphere

    Science.gov (United States)

    Repasky, K. S.; Spuler, S.; Nehrir, A. R.; Moen, D.

    2013-12-01

    Water vapor is the most dominant greenhouse gas in the atmosphere and plays an important role in many key atmospheric processes associated with both weather and climate. Water vapor is highly variable in space and time due to large scale transport and biosphere-atmosphere interactions. Having long-term, high-resolution, vertical profiles of water vapor will help to better understand the water vapor structure and variability and its associated impact on weather and climate. A diode laser based differential absorption lidar (DIAL) for full-time water vapor and aerosol profiling in the lower troposphere has been demonstrated at Montana State University. This prototype instrument has the potential to form the basis of a ground based network of eye-safe autonomous instruments that can provide important information on the spatial and temporal variability of water vapor in the lower troposphere. To achieve this potential, major improvements to the prototype instrument need to be implemented and demonstrated including developing a laser transmitter capable of long term operation and modifying the optical receiver to make measurement below 0.5 km. During the past year, work on incorporating a new laser transmitter based on two distributed Bragg reflector (DBR) diode lasers, one operating at the on-line/side-line wavelength and the second operating at the off-line wavelength to injection seed a tapered semiconductor optical amplifier (TSOA) in a master oscillator power amplifier (MOPA) configuration has been completed. Recent work on the optical receiver is driven by the fact that the majority of the atmospheric water vapor resides below 2 km. The current single channel DIAL receiver has a narrow field of view and does not come in to full overlap until approximately 2 km. A two channel DIAL receiver has been designed that will allow the DIAL to achieve full overlap at ranges of less the 0.5 km providing significant improvement to the instrument performance. A discussion of

  8. Isotopic Controls of Rainwater and Water Vapor on Mangrove Leaf Water and Lipid Biomarkers

    Science.gov (United States)

    Ladd, N.; Wolfshorndl, M.; Sachs, J. P.

    2015-12-01

    Hydrogen isotope ratios (2H/1H or δ2H) of sedimentary mangrove lipid biomarkers can be used as a proxy of past salinity and water isotopes. This approach is based on the observation that apparent 2H/1H fractionation between surface water and mangrove lipids increases with surface water salinity in six species of mangroves with different salt management strategies growing at sites spanning a range of relative humidities throughout Australia and Micronesia. In order to more robustly apply mangrove lipid δ2H as a paleoclimate proxy, we investigated the cause of the correlation between apparent 2H fractionation and salinity. We present results from two related experiments that assessed controls on isotopes of mangrove leaf water, the direct source of hydrogen in lipids: (1) Measurements of natural δ2H in precipitation, surface water, and mangrove tissue water from a series of lakes with varying salinity and water isotope composition in Palau, and (2) measurements of mangrove tissue water and treatment water from a controlled simulation in which mangroves were treated with artificial rain of varying isotopic composition. Rainwater 2H/1H fluctuations of 30‰ over a one-month period explain up to 65% of the variance in leaf water δ2H for Bruguiera gymnorhiza mangroves from Palau despite lake water isotope differences among sites of up to 35‰. This indicates that in humid tropical settings, leaf water isotopes are more closely related to those of precipitation and water vapor than to those of lake surface water, explaining the observed change in apparent fractionation in B. gymnorhiza lipids with salinity. The relationship between leaf water and rainwater isotopes may be due to either equilibration of leaf water with water vapor in the nearly saturated air or direct foliar uptake of rain and/or dew. Foliar uptake is an important water source for many plants, but has not been documented in mangroves. We tested the capacity for mangroves to perform this function by

  9. Interannual variation of water isotopologues at Vostok indicates a contribution from stratospheric water vapor.

    Science.gov (United States)

    Winkler, Renato; Landais, Amaelle; Risi, Camille; Baroni, Melanie; Ekaykin, Alexey; Jouzel, Jean; Petit, Jean Robert; Prie, Frederic; Minster, Benedicte; Falourd, Sonia

    2013-10-29

    Combined measurements of water isotopologues of a snow pit at Vostok over the past 60 y reveal a unique signature that cannot be explained only by climatic features as usually done. Comparisons of the data using a general circulation model and a simpler isotopic distillation model reveal a stratospheric signature in the (17)O-excess record at Vostok. Our data and theoretical considerations indicate that mass-independent fractionation imprints the isotopic signature of stratospheric water vapor, which may allow for a distinction between stratospheric and tropospheric influences at remote East Antarctic sites.

  10. Atmospheric pressure synthesis of photoluminescent hybrid materials by sequential organometallic vapor infiltration into polyethylene terephthalate fibers

    Science.gov (United States)

    Akyildiz, Halil I.; Mousa, Moataz Bellah M.; Jur, Jesse S.

    2015-01-01

    Exposing a polymer to sequential organometallic vapor infiltration (SVI) under low pressure conditions can significantly modify the polymer's chemical, mechanical, and optical properties. We demonstrate that SVI of trimethylaluminum into polyethylene terephthalate (PET) can also proceed readily at atmospheric pressure, and at 60 °C the extent of reaction determined by mass uptake is independent of pressure between 2.5 Torr and 760 Torr. At 120 °C, however, the mass gain is 50% larger at 2.5 Torr relative to that at 760 Torr, indicating that the precursor diffusion in the chamber and fiber matrix decreases at higher source pressure. Mass gain decreases, in general, as the SVI process temperature increases both at 2.5 Torr and 760 Torr attributed to the faster reaction kinetics forming a barrier layer, which prevents further diffusion of the reactive species. The resulting PET/Al-Ox product shows high photoluminescence compared to untreated fibers. A physical mask on the polymer during infiltration at 760 Torr is replicated in the underlying polymer, producing an image in the polymer that is visible under UV illumination. Because of the reduced precursor diffusivity during exposure at 760 Torr, the image shows improved resolution compared to SVI performed under typical 2.5 Torr conditions.

  11. Chemical vapor deposition of high quality graphene films from carbon dioxide atmospheres.

    Science.gov (United States)

    Strudwick, Andrew James; Weber, Nils Eike; Schwab, Matthias Georg; Kettner, Michel; Weitz, R Thomas; Wünsch, Josef R; Müllen, Klaus; Sachdev, Hermann

    2015-01-27

    The realization of graphene-based, next-generation electronic applications essentially depends on a reproducible, large-scale production of graphene films via chemical vapor deposition (CVD). We demonstrate how key challenges such as uniformity and homogeneity of the copper metal substrate as well as the growth chemistry can be improved by the use of carbon dioxide and carbon dioxide enriched gas atmospheres. Our approach enables graphene film production protocols free of elemental hydrogen and provides graphene layers of superior quality compared to samples produced by conventional hydrogen/methane based CVD processes. The substrates and resulting graphene films were characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and Raman microscopy, sheet resistance and transport measurements. The superior quality of the as-grown graphene films on copper is indicated by Raman maps revealing average G band widths as low as 18 ± 8 cm(-1) at 514.5 nm excitation. In addition, high charge carrier mobilities of up to 1975 cm(2)/(V s) were observed for electrons in transferred films obtained from a carbon dioxide based growth protocol. The enhanced graphene film quality can be explained by the mild oxidation properties of carbon dioxide, which at high temperatures enables an uniform conditioning of the substrates by an efficient removal of pre-existing and emerging carbon impurities and a continuous suppression and in situ etching of carbon of lesser quality being co-deposited during the CVD growth.

  12. Escape of atmospheres and loss of water

    Science.gov (United States)

    Hunten, D. M.; Donahue, T. M.; Walker, J. C. G.; Kasting, J. F.

    1989-01-01

    The properties and limitations of several loss processes for atmospheric gases are presented and discussed. They include thermal loss (Jeans and hydrodynamic); nonthermal loss (all processes involve charged particles); and impact erosion, including thermal escape from a molten body heated by rapid accretion. Hydrodynamic escape, or 'blowoff', is of particular interest because it offers the prospect of processing large quantities of gas and enriching the remainder in heavy elements and isotopes. In a second part, the water budgets and likely evolutionary histories of Venus, Earth and Mars are assessed. Although it is tempting to associate the great D/H enrichment on Venus with loss of a large initial endowment, a steady state with juvenile water (perhaps from comets) is equally probable.

  13. Raman Lidar Calibration for the DMSP SSM/T-2 Microwave Water Vapor Sensor

    National Research Council Canada - National Science Library

    Wessel, J

    2000-01-01

    Campaigns were conducted at the Pacific Missile Range Facility, Barking Sands, Kauai, investigating Raman lidar as a method to improve calibration of the DMSP SSM/T-2 microwave water vapor profiling instrument...

  14. Nimbus-6/SCAMS Level 2 Water Vapor and Temperature V001

    Data.gov (United States)

    National Aeronautics and Space Administration — The Nimbus-6 Scanning Microwave Spectrometer (SCAMS) Level 2 data product contains water vapor and temperature profiles. The SCAMS was designed to map tropospheric...

  15. GPM GROUND VALIDATION AEROSOL AND WATER VAPOR LIDAR QUICKLOOKS GCPEX V1

    Data.gov (United States)

    National Aeronautics and Space Administration — The GPM Ground Validation Aerosol and Water Vapor Lidar Quicklooks GCPEx dataset contains imagery generated from the GPM Cold-season Precipitation Experiment (GCPEx)...

  16. Nanostructure Fabrication by Electron-Beam-Induced Deposition with Metal Carbonyl Precursor and Water Vapor

    Science.gov (United States)

    Takeguchi, Masaki; Shimojo, Masayuki; Furuya, Kazuo

    2007-09-01

    Nanorod fabrication is performed by electron beam induced deposition (EBID) with iron carbonyl [Fe(CO)5] and tungsten carbonyl [W(CO)6] precursors. The effects of water vapor addition to each metal carbonyl on the microstructure and composition of the obtained nanorods are studied. Normally, EBID-fabricated metal nanorods consist of an amorphous phase containing a considerable amount of carbon. However, it is found that water vapor addition to iron carbonyl can effectively reduce the carbon content of the nanorods and induce the formation of carbon-free crystalline Fe3O4 nanorods with increasing partial pressure ratio of water vapor to iron carbonyl. In contrast, for tungsten carbonyl, water vapor addition has no obvious effect on carbon content reduction. The obtained nanorods consist of a carbon-rich amorphous matrix containing tungsten oxide nanocrystals inside.

  17. MLS/Aura Level 2 Water Vapor (H2O) Mixing Ratio V004

    Data.gov (United States)

    National Aeronautics and Space Administration — ML2H2O is the EOS Aura Microwave Limb Sounder (MLS) standard product for water vapor derived from radiances measured primarily by the 190 GHz radiometer. The current...

  18. MLS/Aura L2 Water Vapor (H2O) Mixing Ratio V002

    Data.gov (United States)

    National Aeronautics and Space Administration — ML2H2O is the EOS Aura Microwave Limb Sounder (MLS) standard product for water vapor derived from radiances measured primarily by the 190 GHz radiometer. The current...

  19. SAFARI 2000 AOT and Column Water Vapor, Kalahari Transect, Wet Season 2000

    Data.gov (United States)

    National Aeronautics and Space Administration — ABSTRACT: The data presented here include the aerosol optical thickness (AOT) and column water vapor measurements taken at sites along the Kalahari Transect using a...

  20. Solid State Transmitters for Water Vapor and Ozone DIAL Systems Project

    Data.gov (United States)

    National Aeronautics and Space Administration — We have developed a common architecture for laser transmitters that address requirements for water vapor as well as ground and airborne ozone lidar systems. Our...

  1. Scanning Multichannel Microwave Radiometer (SMMR) Monthly Mean Integrated Water Vapor (IWV) By Prabhakara

    Data.gov (United States)

    National Aeronautics and Space Administration — SMMR_IWV_PRABHAKARA data are Special Multichannel Microwave Radiometer (SMMR) Monthly Mean Integrated Water Vapor (IWV) data by Prabhakara.The Scanning Multichannel...

  2. Solid State Transmitters for Water Vapor and Ozone DIAL Systems Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The focus of this Select Phase II program is to build and deliver laser components both for airborne water vapor and ozone DIAL systems. Specifically, Fibertek...

  3. EPA Method 245.1: Determination of Mercury in Water by Cold Vapor Atomic Absorption Spectrometry

    Science.gov (United States)

    SAM lists this method for preparation and analysis of aqueous liquid and drinking water samples. This method will determine mercuric chloride and methoxyethylmercuric acetate as total mercury using cold vapor atomic absorption spectrometry.

  4. Polymer functionalized nanostructured porous silicon for selective water vapor sensing at room temperature

    Science.gov (United States)

    Dwivedi, Priyanka; Das, Samaresh; Dhanekar, Saakshi

    2017-04-01

    This paper highlights the surface treatment of porous silicon (PSi) for enhancing the sensitivity of water vapors at room temperature. A simple and low cost technique was used for fabrication and functionalization of PSi. Spin coated polyvinyl alcohol (PVA) was used for functionalizing PSi surface. Morphological and structural studies were conducted to analyze samples using SEM and XRD/Raman spectroscopy respectively. Contact angle measurements were performed for assessing the wettability of the surfaces. PSi and functionalized PSi samples were tested as sensors in presence of different analytes like ethanol, acetone, isopropyl alcohol (IPA) and water vapors in the range of 50-500 ppm. Electrical measurements were taken from parallel aluminium electrodes fabricated on the functionalized surface, using metal mask and thermal evaporation. Functionalized PSi sensors in comparison to non-functionalized sensors depicted selective and enhanced response to water vapor at room temperature. The results portray an efficient and selective water vapor detection at room temperature.

  5. Liquid-phase and vapor-phase dehydration of organic/water solutions

    Science.gov (United States)

    Huang, Yu [Palo Alto, CA; Ly, Jennifer [San Jose, CA; Aldajani, Tiem [San Jose, CA; Baker, Richard W [Palo Alto, CA

    2011-08-23

    Processes for dehydrating an organic/water solution by pervaporation or vapor separation using fluorinated membranes. The processes are particularly useful for treating mixtures containing light organic components, such as ethanol, isopropanol or acetic acid.

  6. MLS/Aura L2 Water Vapor (H2O) Mixing Ratio V003

    Data.gov (United States)

    National Aeronautics and Space Administration — ML2H2O is the EOS Aura Microwave Limb Sounder (MLS) standard product for water vapor derived from radiances measured primarily by the 190 GHz radiometer. The current...

  7. Using an Atmospheric Pressure Chemical Vapor Deposition Process for the Development of V2O5 as an Electrochromic Material

    Directory of Open Access Journals (Sweden)

    Dimitra Vernardou

    2017-02-01

    Full Text Available Vanadium pentoxide coatings were grown by atmospheric pressure chemical vapor deposition varying the gas precursor ratio (vanadium (IV chloride:water and the substrate temperature. All samples were characterized by X-ray diffraction, Raman spectroscopy, scanning electron microscopy, cyclic voltammetry, and transmittance measurements. The water flow rate was found to affect the crystallinity and the morphological characteristics of vanadium pentoxide. Dense stacks of long grains of crystalline oxide are formed at the highest amount of water utilized for a substrate temperature of 450 °C. Accordingly, it was indicated that for higher temperatures and a constant gas precursor ratio of 1:7, the surface morphology becomes flattened, and columnar grains of uniform size and shape are indicated, keeping the high crystalline quality of the material. Hence, it was possible to define a frame of operating parameters wherein single-phase vanadium pentoxide may be reliably expected, including a gas precursor ratio of 1:7 with a substrate temperature of >450 °C. The as-grown vanadium pentoxide at 550 °C for a gas precursor ratio of 1:7 presented the best electrochemical performance, including a diffusion coefficient of 9.19 × 10−11 cm2·s−1, a charge density of 3.1 mC·cm−2, and a coloration efficiency of 336 cm2·C−1. One may then say that this route can be important for the growth of large-scale electrodes with good performance for electrochromic devices.

  8. Is There Evidence of Convectively Injected Water Vapor in the Lowermost Stratosphere Over Boulder, Colorado?

    Science.gov (United States)

    Hurst, D. F.; Rosenlof, K. H.; Davis, S. M.; Hall, E. G.; Jordan, A. F.

    2014-12-01

    Anderson et al. (2012) reported the frequent presence of convectively injected water vapor in the lowermost stratosphere over North America during summertime, based on aircraft measurements. They asserted that enhanced catalytic ozone destruction within these wet stratospheric air parcels presents a concern for UV dosages in populated areas, especially if the frequency of deep convective events increases. Schwartz et al.(2013) analyzed 8 years of more widespread Aura Microwave Limb Sounder (MLS) measurements of lower stratospheric water vapor over North America and concluded that anomalously wet (>8 ppm) air parcels were present only 2.5% of the time during July and August. However, given the 3-km vertical resolution of MLS water vapor retrievals in the lowermost stratosphere, thin wet layers deposited by overshooting convection may be present but not readily detectable by MLS. Since 1980 the balloon-borne NOAA frost point hygrometer (FPH) has produced nearly 400 high quality water vapor profiles over Boulder, Colorado, at 5-m vertical resolution from the surface to the middle stratosphere. The 34-year record of high-resolution FPH profiles obtained over Boulder during summer months is evaluated for evidence of convectively injected water vapor in the lowermost stratosphere. A number of approaches are used to assess the contributions of deep convection to the Boulder stratospheric water vapor record. The results are compared to those based on MLS profiles over Boulder and the differences are discussed. Anderson, J. G., D. M. Wilmouth, J. B. Smith, and D. S. Sayres (2012), UV dosage levels in summer: Increased risk of ozone loss from convectively injected water vapor, Science, 337(6096), 835-839, doi:10.1126/science.1222978. Schwartz, M. J., W. G. Read, M. L. Santee, N. J. Livesey, L. Froidevaux, A. Lambert, and G. L. Manney (2013), Convectively injected water vapor in the North American summer lowermost stratosphere, Geophys. Res. Lett., 40, 2316-2321, doi:10

  9. Effects of altitude on transpiration, leaf vapor pressure deficit and leaf water potential in oriental beech

    Directory of Open Access Journals (Sweden)

    Fatih Bayraktar

    2015-04-01

    Full Text Available This study was designed to determine the effect of altitude on transpiration, leaf vapor pressure deficit and leaf water potential in oriental beech (Fagus orientalis Lipsky. The study area was located in Ortaköy, Artvin, and the experimental area had the same soil structure and aspect. The study showed that transpiration and leaf vapor pressure deficit increased but leaf water potential decreased by altitudinal gradient

  10. Water Vapor Permeability of Edible Films Based on Improved Cassava (Manihot esculenta Crantz) Native Starches

    OpenAIRE

    Adjouman, Yao Désiré; Nindjin, Charlemagne; Tetchi, F.Achille; Dalcq, Anne-Catherine; Amani, N.Georges; Sindic, Marianne

    2017-01-01

    Starch is used in the production of edible biodegradable packaging as an attractive alternative to synthetic polymers because it is a natural biopolymer of low cost and high availability. Many studies have been carried out on films based on cassava starch and the results show that these have good flexibility and low water vapor permeability. This present research was conducted to analyse the effect of glycerol, peanut oil and soybean lecithin on the water vapor permeability (WVP) of edible fi...

  11. The Potential of Water Vapor & Precipitation Estimation with a Differential-frequency Radar

    Science.gov (United States)

    Meneghini, Robert; Liao, Liang; Tian, Lin

    2006-01-01

    In the presence of rain, the radar return powers from a three-frequency radar, with center frequency at 22.235 GHz and upper and lower frequencies chosen with equal water vapor absorption coefficients, can be used to estimate water vapor density and parameters of the precipitation. A linear combination of differential measurements between the center and lower frequencies on one hand and the upper and lower frequencies on the other provide an estimate of differential water vapor absorption. Conversely, the difference in radar reflectivity factors (in dB) between the upper and lower frequencies is independent of water vapor absorption and can be used to estimate the median mass diameter of the hydrometeors. For a down-looking radar, path-integrated estimates of water vapor absorption may be possible under rain-free as well as raining conditions by using the surface returns at the three frequencies. Cross-talk or interference between the precipitation and water vapor estimates depends on the frequency separation of the channels as well as on the phase state and the median mass diameter of the hydrometeors. Simulations of the retrieval of water vapor absorption show that the largest source of variability arises from the variance in the measured radar return powers while the largest biases occur in the mixed-phase region. Use of high pulse repetition frequencies and signal whitening methods may be needed to obtain the large number of independent samples required. Measurements over a fractional bandwidth, defined as the ratio of the difference between the upper and lower frequencies to the center frequency, up to about 0.2 should be passible in a differential frequency mode, where a single transceiver and antenna are used. Difficulties in frequency allocation may require alternative choices of frequency where the water vapor absorptions at the low and high frequencies are unequal. We consider the degradation in the retrieval accuracy when the frequencies are not optimum.

  12. Use of Interrupted Helium Flow in the Analysis of Vapor Samples with Flowing Atmospheric-Pressure Afterglow-Mass Spectrometry

    Science.gov (United States)

    Storey, Andrew P.; Zeiri, Offer M.; Ray, Steven J.; Hieftje, Gary M.

    2017-02-01

    The flowing atmospheric-pressure afterglow (FAPA) source was used for the mass-spectrometric analysis of vapor samples introduced between the source and mass spectrometer inlet. Through interrupted operation of the plasma-supporting helium flow, helium consumption is greatly reduced and dynamic gas behavior occurs that was characterized by schlieren imaging. Moreover, mass spectra acquired immediately after the onset of helium flow exhibit a signal spike before declining and ultimately reaching a steady level. This initial signal appears to be due to greater interaction of sample vapor with the afterglow of the source when helium flow resumes. In part, the initial spike in signal can be attributed to a pooling of analyte vapor in the absence of helium flow from the source. Time-resolved schlieren imaging of the helium flow during on and off cycles provided insight into gas-flow patterns between the FAPA source and the MS inlet that were correlated with mass-spectral data.

  13. INTRODUCTION: Anticipated changes in the global atmospheric water cycle

    Science.gov (United States)

    Allan, Richard P.; Liepert, Beate G.

    2010-06-01

    an important example. Understanding surface solar 'dimming' and 'brightening' trends in the context of past and current changes in the water cycle are discussed in a guest editorial by Wild and Liepert (2010). The key roles anthropogenic aerosols can play on a regional scale are discussed by Lau et al (2010) through their study of the regional impact of absorbing aerosols on warming and snow melt over the Himalayas. The overarching goal of climate prediction is to provide reliable, probabilistic estimates of future changes. Relating hydrological responses back to a sound physical basis, the motivation for this special focus issue, is paramount in building confidence in anticipated changes, especially in the global water cycle. We are grateful to the reviewers and the journal editorial board for making this focus issue possible. Focus on Anticipated Changes in the Global Atmospheric Water Cycle Contents Editorials The global atmospheric water cycle Lennart Bengtsson The Earth radiation balance as driver of the global hydrological cycle Martin Wild and Beate Liepert Letters Enhanced surface warming and accelerated snow melt in the Himalayas and Tibetan Plateau induced by absorbing aerosols William K M Lau, Maeng-Ki Kim, Kyu-Myong Kim and Woo-Seop Lee Current changes in tropical precipitation Richard P Allan, Brian J Soden, Viju O John, William Ingram and Peter Good Direct versus indirect effects of tropospheric humidity changes on the hydrologic cycle S C Sherwood How closely do changes in surface and column water vapor follow Clausius-Clapeyron scaling in climate change simulations? P A O'Gorman and C J Muller Linking increases in hourly precipitation extremes to atmospheric temperature and moisture changes Geert Lenderink and Erik van Meijgaard Are climate-related changes to the character of global-mean precipitation predictable? Graeme L Stephens and Yongxiang Hu A comparison of large scale changes in surface humidity over land in observations and CMIP3 general

  14. Measurement of Turbulent Water Vapor Fluxes from Lightweight Unmanned Aircraft Systems

    Science.gov (United States)

    Thomas, R. M.; Ramanathan, V.; Nguyen, H.; Lehmann*, K.

    2010-12-01

    Scientists at the Center for Clouds, Chemistry and Climate (C4) at the Scripps Institution of Oceanography have successfully used Unmanned Aircraft Systems (UASs) for measurements of radiation fluxes, aerosol concentrations and cloud microphysical properties. Building on this success, a payload to measure water vapor fluxes using the eddy covariance (EC) technique has been recently developed and tested. To our knowledge this is the first UAS turbulent flux system to incorporate high-frequency water vapor measurements. The driving aim of the water vapor flux system’s development is to investigate ‘atmospheric rivers’ in the north-western Pacific Ocean, these can lead to sporadic yet extreme rainfall and flooding events upon landfall in California. Such a flux system may also be used to investigate other weather events (e.g. the formation of hurricanes) and offers a powerful aerosol-cloud-radiative forcing investigative tool when combined with the existing aerosol/radiation and cloud microphysics UAS payloads. The atmospheric vertical wind component (w) is derived by this system at up to 100Hz using data from a GPS/Inertial Measurement Unit (GPS/IMU) combined with a fast-response gust probe mounted on the UAV. Measurements of w are then combined with equally high frequency water vapor data (collected using a Campbell Scientific Krypton Hygrometer) to calculate latent heat fluxes (λE). Two test flights were conducted at the NASA Dryden test facility on 27th May 2010, located in the Mojave Desert. Horizontal flight legs were recorded at four altitudes between 1000-2500 masl within the convective boundary layer. Preliminary data analysis indicates averaged spectral data follow the theoretical -5/3 slope , and extrapolation of the flux profile to the surface resulted in λE of 1.6 W m-2; in good agreement with 1.0 W m-2 λE measured by NOAA from a surface tower using standard flux techniques. The system performance during the Dryden test, as well as subsequent

  15. Storage of pork meat under modified atmospheres containing vapors from commercial alcoholic beverages.

    Science.gov (United States)

    Kapetanakou, A E; Agathaggelou, E I; Skandamis, P N

    2014-05-16

    The present study aimed to evaluate the effect of AB vapors on microbial, physicochemical, and sensory profile of pork meat stored in different MAP conditions. Pork pieces (10g) and cotton/cellulose absorbent cloths (2×2cm) were placed into compartmentalized Petri-dishes in two sections. Aliquots (1mL) of water (control), 30% v/v and 40% v/v ethanol, whisky, brandy, tsipouro, raki, and ouzo were added separately to the cotton/cellulose absorbent cloths. Each pork sample was placed in one compartment and cotton/cellulose absorbent cloths supplemented with different ABs were placed in a separate compartment of each Petri-dish. Samples were packaged in 40% CO2: 30% O2: 30% N2 and 80% O2: 20% CO2 and stored at 4 and 10°C. Total viable counts, Pseudomonas sp., Brochothrix thermosphacta, lactic acid bacteria, yeasts and molds, and Enterobacteriaceae, were enumerated during storage. Changes in pH, color (L*, a*, b*), odor, taste, and overall appearance of pork meat were also evaluated along with changes in organic acid levels via HPLC. At 4°C, lactic acid bacteria and B. thermosphacta were the dominant organisms under 40% CO2: 30% N2: 30% O2 and 80% O2: 20% CO2, respectively, while at 10°C, lactic acid bacteria dominated in both MAP conditions. All applied ABs were effective (palcoholic beverages (especially ouzo) under 80% O2: 20% CO2 resulted in better (p<0.05) sensory properties compared to the respective samples under 40% CO2: 30% O2: 30% N2. Overall, vapor action of ABs in combination with MAP may constitute a promising, antimicrobial packaging technology for extending the shelf-life of pork meat. Copyright © 2014 Elsevier B.V. All rights reserved.

  16. Large Scale Water Vapor Sources Relative to the October 2000 Piedmont Flood

    Science.gov (United States)

    Turato, Barbara; Reale, Oreste; Siccardi, Franco

    2003-01-01

    Very intense mesoscale or synoptic-scale rainfall events can occasionally be observed in the Mediterranean region without any deep cyclone developing over the areas affected by precipitation. In these perplexing cases the synoptic situation can superficially look similar to cases in which very little precipitation occurs. These situations could possibly baffle the operational weather forecasters. In this article, the major precipitation event that affected Piedmont (Italy) between 13 and 16 October 2000 is investigated. This is one of the cases in which no intense cyclone was observed within the Mediterranean region at any time, only a moderate system was present, and yet exceptional rainfall and flooding occurred. The emphasis of this study is on the moisture origin and transport. Moisture and energy balances are computed on different space- and time-scales, revealing that precipitation exceeds evaporation over an area inclusive of Piedmont and the northwestern Mediterranean region, on a time-scale encompassing the event and about two weeks preceding it. This is suggestive of an important moisture contribution originating from outside the region. A synoptic and dynamic analysis is then performed to outline the potential mechanisms that could have contributed to the large-scale moisture transport. The central part of the work uses a quasi-isentropic water-vapor back trajectory technique. The moisture sources obtained by this technique are compared with the results of the balances and with the synoptic situation, to unveil possible dynamic mechanisms and physical processes involved. It is found that moisture sources on a variety of atmospheric scales contribute to this event. First, an important contribution is caused by the extratropical remnants of former tropical storm Leslie. The large-scale environment related to this system allows a significant amount of moisture to be carried towards Europe. This happens on a time- scale of about 5-15 days preceding the

  17. Turbulent mixed convection of heat and water vapor transfers in a two-dimensional vegetation canopy

    Energy Technology Data Exchange (ETDEWEB)

    Banna, M. [Laboratoire sur l' Energie Solaire, Universite de Lome, Faculte des Sciences, BP 1515, Lome (Togo); Pietri, L.; Zeghmati, B. [Centre d' Etudes Fondamentales, Groupe de Mecanique Acoustique et Instrumentation (CEF-GMAI), Universite de Perpignan, 52 avenue de Villeneuve, 66860 Perpignan (France)

    2004-08-01

    The present study consists in a numerical investigation of turbulent mixed-convection of heat and water vapor transfers inside two-dimensional (2-D) vegetation canopy, in the surrounding atmosphere and in a wet underground. The time-averaged Navier-Stokes equations are used to characterize the flow field surrounding the canopy and within it. Reynolds shear stresses are calculated using the eddy turbulence model and the Prandtl mixing length. The governing equations are solved numerically using an implicit finite difference method and Thomas algorithm. The present model is used for the determination of the micro climatic profiles such as streamlines, isotherms and iso-concentration. Special emphasis is laid on the systematic analysis of the total evaporation rate (evapotranspiration), the local and average heat fluxes, the Nusselt and Sherwood numbers. The effects of Leaf Area Density distribution, the canopy stomata regulation, as well as the atmospheric forcing conditions on the transfers, are presented and analysed. The results show that buoyancy force caused by properties variation reduces the local heat and mass transfer coefficients, and that this reduction increases at lower wind velocities. (orig.)

  18. Total column water vapor estimation over land using radiometer data from SAC-D/Aquarius

    Science.gov (United States)

    Epeloa, Javier; Meza, Amalia

    2018-02-01

    The aim of this study is retrieving atmospheric total column water vapor (CWV) over land surfaces using a microwave radiometer (MWR) onboard the Scientific Argentine Satellite (SAC-D/Aquarius). To research this goal, a statistical algorithm is used for the purpose of filtering the study region according to the climate type. A log-linear relationship between the brightness temperatures of the MWR and CWV obtained from Global Navigation Satellite System (GNSS) measurements was used. In this statistical algorithm, the retrieved CWV is derived from the Argentinian radiometer's brightness temperature which works at 23.8 GHz and 36.5 GHz, and taking into account CWVs observed from GNSS stations belonging to a region sharing the same climate type. We support this idea, having found a systematic effect when applying the algorithm; it was generated for one region using the previously mentioned criteria, however, it should be applied to additional regions, especially those with other climate types. The region we analyzed is in the Southeastern United States of America, where the climate type is Cfa (Köppen - Geiger classification); this climate type includes moist subtropical mid-latitude climates, with hot, muggy summers and frequent thunderstorms. However, MWR only contains measurements taken from over ocean surfaces; therefore the determination of water vapor over land is an important contribution to extend the use of the SAC-D/Aquarius radiometer measurements beyond the ocean surface. The CWVs computed by our algorithm are compared against radiosonde CWV observations and show a bias of about -0.6 mm, a root mean square (rms) of about 6 mm and a correlation of 0.89.

  19. MIAWARA-C, a new ground based water vapor radiometer for measurement campaigns

    Directory of Open Access Journals (Sweden)

    C. Straub

    2010-09-01

    Full Text Available In this paper a new 22 GHz water vapor spectro-radiometer which has been specifically designed for profile measurement campaigns of the middle atmosphere is presented. The instrument is of a compact design and has a simple set up procedure. It can be operated as a standalone instrument as it maintains its own weather station and a calibration scheme that does not rely on other instruments or the use of liquid nitrogen. The optical system of MIAWARA-C combines a choked gaussian horn antenna with a parabolic mirror which reduces the size of the instrument in comparison with currently existing radiometers. For the data acquisition a correlation receiver is used together with a digital cross correlating spectrometer. The complete backend section, including the computer, is located in the same housing as the instrument. The receiver section is temperature stabilized to minimize gain fluctuations. Calibration of the instrument is achieved through a balancing scheme with the sky used as the cold load and the tropospheric properties are determined by performing regular tipping curves. Since MIAWARA-C is used in measurement campaigns it is important to be able to determine the elevation pointing in a simple manner as this is a crucial parameter in the calibration process. Here we present two different methods; scanning the sky and the Sun. Finally, we report on the first spectra and retrieved water vapor profiles acquired during the Lapbiat campaign at the Finnish Meteorological Institute Arctic Research Centre in Sodankylä, Finland. The performance of MIAWARA-C is validated here by comparison of the presented profiles against the equivalent profiles from the Microwave Limb Sounder on the EOS/Aura satellite.

  20. Densities and vapor pressures of mixed-solvent desiccant systems containing {l_brace}glycol (diethylene, or triethylene, or tetraethylene glycol) + salt (magnesium chloride) + water{r_brace}

    Energy Technology Data Exchange (ETDEWEB)

    Chen Shangyi [R and D Center for Membrane Technology, Department of Chemical Engineering, Chung Yuan Christian University, Chung Li 32023, Taiwan (China); Soriano, Allan N. [R and D Center for Membrane Technology, Department of Chemical Engineering, Chung Yuan Christian University, Chung Li 32023, Taiwan (China); School of Chemical Engineering and Chemistry, Mapua Institute of Technology, Manila 1002 (Philippines); Li Menghui, E-mail: mhli@cycu.edu.t [R and D Center for Membrane Technology, Department of Chemical Engineering, Chung Yuan Christian University, Chung Li 32023, Taiwan (China)

    2010-09-15

    In this present work, new experimental data for density and vapor pressure of the mixed-solvent desiccant systems containing {l_brace}(40.0 wt%) glycol + salt + water{r_brace} were reported for temperatures up to 343.15 K at normal atmospheric condition. The considered glycols were diethylene, triethylene, and tetraethylene glycol; and the salt is magnesium chloride (wt% = 4.0, 9.0, and 16.0). The density and vapor pressure were presented as functions of temperature and compositions. An empirical equation was used to correlate the temperature and compositional dependence of the present density data and a model based on the mean spherical approximation for aqueous electrolyte solutions incorporating the pseudo-solvent approach was used to represent the measured vapor pressure as functions of temperature and composition. Satisfactory results were obtained for both density and vapor pressure calculations.

  1. Satellite Retrieval of Atmospheric Water Budget over Gulf of Mexico- Caribbean Basin: Seasonal Variability

    Science.gov (United States)

    Smith, Eric A.; Santos, Pablo; Einaudi, Franco (Technical Monitor)

    2001-01-01

    This study presents results from a multi-satellite/multi-sensor retrieval system designed to obtain the atmospheric water budget over the open ocean. A combination of hourly-sampled monthly datasets derived from the GOES-8 5 Imager and the DMSP 7-channel passive microwave radiometer (SSM/I) have been acquired for the Gulf of Mexico-Caribbean Sea basin. Whereas the methodology is being tested over this basin, the retrieval system is designed for portability to any open-ocean region. Algorithm modules using the different datasets to retrieve individual geophysical parameters needed in the water budget equation are designed in a manner that takes advantage of the high temporal resolution of the GOES-8 measurements, as well as the physical relationships inherent to the SSM/I passive microwave signals in conjunction with water vapor, cloud liquid water, and rainfall. The methodology consists of retrieving the precipitation, surface evaporation, and vapor-cloud water storage terms in the atmospheric water balance equation from satellite techniques, with the water vapor advection term being obtained as the residue needed for balance. Thus, we have sought to develop a purely satellite-based method for obtaining the full set of terms in the atmospheric water budget equation without requiring in situ sounding information on the wind profile. The algorithm is partly validated by first cross-checking all the algorithm components through multiple-algorithm retrieval intercomparisons. More fundamental validation is obtained by directly comparing water vapor transports into the targeted basin diagnosed from the satellite algorithm to those obtained observationally from a network of land-based upper air stations that nearly uniformly surround the basin. Total columnar atmospheric water budget results will be presented for an extended annual cycle consisting of the months of October-97, January-98, April-98, July-98, October-98, and January-1999. These results are used to emphasize

  2. Evaluation of continuous water vapor δD and δ18O measurements by off-axis integrated cavity output spectroscopy

    Directory of Open Access Journals (Sweden)

    L. J. Araguas-Araguas

    2012-08-01

    Full Text Available Recent commercially available laser spectroscopy systems enabled us to continuously and reliably measure the δD and δ18O of atmospheric water vapor. The use of this new technology is becoming popular because of its advantages over the conventional approach based on cold trap collection. These advantages include much higher temporal resolution/continuous monitoring and the ability to make direct measurements of both isotopes in the field. Here, we evaluate the accuracy and precision of the laser based water vapor isotope instrument through a comparison of measurements with those found using the conventional cold trap method. A commercially available water vapor isotope analyzer (WVIA with the vaporization system of a liquid water standard (Water Vapor Isotope Standard Source, WVISS from Los Gatos Research (LGR Inc. was used for this study. We found that the WVIA instrument can provide accurate results if (1 correction is applied for time-dependent isotope drift, (2 normalization to the VSMOW/SLAP scale is implemented, and (3 the water vapor concentration dependence of the isotopic ratio is also corrected. In addition, since the isotopic value of water vapor generated by the WVISS is also dependent on the concentration of water vapor, this effect must be considered to determine the true water vapor concentration effect on the resulting isotope measurement. To test our calibration procedure, continuous water vapor isotope measurements using both a laser instrument and a cold trap system were carried out at the IAEA Isotope Hydrology Laboratory in Vienna from August to December 2011. The calibrated isotopic values measured using the WVIA agree well with those obtained via the cold trap method. The standard deviation of the isotopic difference between both methods is about 1.4‰ for δD and 0.28‰ for δ18O. This precision allowed us to obtain reliable values for d-excess. The day-to-day variation of d-excess measured by WVIA also agrees well

  3. Portable device for generation of ultra-pure water vapor feeds

    Science.gov (United States)

    Velin, P.; Stenman, U.; Skoglundh, M.; Carlsson, P.-A.

    2017-11-01

    A portable device for the generation of co-feeds of water vapor has been designed, constructed, and evaluated for flexible use as an add-on component to laboratory chemical reactors. The vapor is formed by catalytic oxidation of hydrogen, which benefits the formation of well-controlled minute concentrations of ultra-pure water. Analysis of the effluent stream by on-line mass spectrometry and Fourier transform infrared spectroscopy confirms that water vapor can be, with high precision, generated both rapidly and steadily over extended periods in the range of 100 ppm to 3 vol. % (limited by safety considerations) using a total flow of 100 to 1500 ml/min at normal temperature and pressure. Further, the device has been used complementary to a commercial water evaporator and mixing system to span water concentrations up to 12 vol. %. Finally, an operando diffuse reflective infrared Fourier transform spectroscopic measurement of palladium catalysed methane oxidation in the absence and presence of up to 1.0 vol. % water has been carried out to demonstrate the applicability of the device for co-feeding well-controlled low concentrations of water vapor to a common type of spectroscopic experiment. The possibilities of creating isotopically labeled water vapor as well as using tracer gases for dynamic experiments are discussed.

  4. Controls on water vapor isotopes over Roorkee, India: Impact of convective activities and depression systems

    Science.gov (United States)

    Saranya, P.; Krishan, Gopal; Rao, M. S.; Kumar, Sudhir; Kumar, Bhishm

    2018-02-01

    The study evaluates the water vapor isotopic compositions and its controls with special reference to Indian Summer Monsoon (ISM) season at Roorkee, India. Precipitation is usually a discrete event spatially and temporally in this part of the country, therefore, the information provided is limited, while, the vapors have all time availability and have a significant contribution in the hydrological cycle locally or over a regional scale. Hence for understanding the processes altering the various sources, its isotopic signatures were studied. The Isotope Water Vapour Line (Iso Val) was drawn together with the Global Meteoric Water Line (GMWL) and the best fit line was δD = 5.42 * δ18O + 27.86. The precipitation samples were also collected during the study period and were best fitted with δD = 8.20(±0.18) * δ18O + 9.04(±1.16) in the Local Meteoric Water Line (LMWL). From the back trajectory analysis of respective vapor samples, it is unambiguous that three major sources viz; local vapor, western disturbance and monsoon vapor are controlling the fate of moisture over Roorkee. The d-excess in ground-level vapor (GLV) reveals the supply of recycled moisture from continental water bodies and evapo-transpiration as additional moisture sources to the study area. The intensive depletion in isotopic ratios was associated with the large-scale convective activity and low-pressure/cyclonic/depression systems formed over Bay of Bengal.

  5. Colorimetric Detection of Water Vapor Using Metal-Organic Framework Composites.

    Energy Technology Data Exchange (ETDEWEB)

    Allendorf, Mark D. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2017-12-01

    Purpose: Water vapor trapped in encapsulation materials or enclosed volumes leads to corrosion issues for critical NW components. Sandia National Laboratories has created a new diagnostic to indicate the presence of water in weapon systems. Impact: Component exposure to water now can be determined instantly, without need for costly, time-consuming analytical methods.

  6. Studies in graphene growth and processing using atmospheric pressure chemical vapor deposition

    Science.gov (United States)

    Merrell, Andrew Nephi

    This dissertation focuses on graphene, a promising two-dimensional, carbon material with many favorable electronic properties. The prospect of implementing graphene into a wide variety of potential device applications is enticing, but many factors stand in the way before this goal is realized. Atmospheric pressure chemical vapor deposition (APCVD) is a graphene production method that may be compatible with large-scale growth. Motivated by the need to more fully understand APCVD growth of graphene, a system is constructed, and several studies are carried out. Specifically, a detailed study is presented which involves the effects of hydrogen and contaminant oxygen in APCVD-grown graphene. The research shows that hydrogen is an important factor to control during the cooling stage of APCVD, as it has a direct effect on the formation of oxides on the copper foil (copper is used as the catalyst for graphene growth in APCVD). It is also determined that hydrogen, as well as the reaction chamber, play an important role in the formation of SiO2 nanoparticles, which accumulate on the copper surface during graphene growth. Methods for patterning and processing graphene are also explored in this dissertation, as such methods are crucial in the realization of graphene-based devices. The method of e-beam assisted metal deposition used in conjunction with masked-CVD growth is proposed as an effective alternative to conventional processing methods such as photolithography and electron-beam lithography. The proposed methods have several advantages, which pave the way for lowering graphene/metal contact resistance, and preserving the intrinsic properties of graphene during device fabrication.

  7. Stable isotopic variations of water vapor on the winter coastal area in Korea

    Science.gov (United States)

    Lee, Jeonghoon; Lee, Songyi; Han, Yeongcheol; Do Hur, Soon

    2017-04-01

    Studies of isotopic compositions of precipitation in Korea have been conducted for groundwater mixing and sources and residence time of water. Unravelling of water vapor isotopes will be very helpful in explaining the sources of moisture. In this work, we first present isotopic compositions of water vapor over western part of Korea in winter between December 2015 and February 2016. We collected the samples of water vapor isotopes by a cryogenic method with impingers and liquid nitrogen. We captured the water vapor for 4 to 6 hours, depending on humidity and collected 54 samples in total. The samples were analyzed by a Picarro L2130-i and the precisions were 0.06‰ and 0.7‰ for oxygen and hydrogen, respectively. The isotopic compositions of water vapor ranged from -34.04‰ to -15.27‰ for oxygen and from -221.9‰ to -100.2‰ for hydrogen. The deuterium excess (d=δD-8*δ18O) was between 17.4 and 44.0 in permil. Both air temperature (T, δ18O=0.57*T-25.5, R2=0.46) and relative humidity (RH, δ18O=0.18*RH-35.9, R2=0.38) were positively correlated with the water vapor isotopes. This is not consistent with the fact that precipitation isotopes are correlated with only temperate in winter Eastern Asia. We expect that the water vapor isotopes will be an important role to understand the origin and pathway of moistures over the Eastern Asia.

  8. Effects of water vapor on flue gas conditioning in the electric fields with corona discharge

    Energy Technology Data Exchange (ETDEWEB)

    Liqiang, QI, E-mail: qi_liqiang@163.com; Yajuan, Zhang

    2013-07-15

    Highlights: • The influence mechanism of water vapor humidification on SO{sub 2} oxidation was analyzed. •The effects of water vapor on the specific resistance in fly ash in ESPs were reported. • The effects of water vapor on the size distribution and specific surface area of fly ash were discussed. • The adhesive characteristic of fly ash in different water vapor was experimented. -- Abstract: Sulfur dioxide (SO{sub 2}) removal via pulsed discharge nonthermal plasma in the absence of ammonia was investigated to determine how electrostatic precipitators (ESPs) can effectively collect particulate matter less than 2.5 μm in diameter from flue gas. SO{sub 2} removal increased as water vapor concentration increased. In a wet-type plasma reactor, directing a gas-phase discharge plasma toward the water film surface significantly enhanced the liquid-phase oxidation of HSO{sub 3}{sup −} to SO{sub 4}{sup 2−}. Comparisons of various absorbents revealed that the hydroxyl radical is a key factor in plasma-induced liquid-phase reactions. The resistivity, size distribution, and cohesive force of fly ash at different water vapor contents were measured using a Bahco centrifuge, which is a dust electrical resistivity test instrument, as well as a cohesive force test apparatus developed by the researchers. When water vapor content increased by 5%, fly ash resistivity in flue gas decreased by approximately two orders of magnitude, adhesive force and size increased, and specific surface area decreased. Therefore, ESP efficiency increased.

  9. SEPARATION OF WATER VAPORS FROM AIR BY SORPTION ON SOME COMPOSITE MATERIALS

    Directory of Open Access Journals (Sweden)

    OANA HAUTĂ

    2014-01-01

    Full Text Available This work presents an experimental investigation of the kinetics of water vapor sorption on two composites synthesized by impregnating activated carbon and activated alumina respectively with lithium bromide (named as MCA2 and MCC2 respectively. The obtained results showed an increase in water amount adsorbed on both composite materials. Due to different chemical natures of the host matrices, the water sorption kinetics on MCC2 is faster compared to that of MCA2. The presence of calcium chloride instead of lithium bromide in alumina pores will determine a shorter breakthrough time and a higher adsorption rate of water vapors.

  10. Laboratory Experiments to Investigate the Exchange of Water Between the Atmosphere and Surface on Mars

    Science.gov (United States)

    Nikolakakos, G.; Whiteway, J. A.

    2016-12-01

    Laboratory chamber experiments have been carried out to investigate the exchange of water between the atmosphere and surface on Mars. Raman Scattering was applied to detect water uptake by samples of magnesium perchlorate hexahydrate. When exposed to the water vapor pressure and temperatures found at the Phoenix landing site, magnesium perchlorate hexahydrate samples of the size found on Mars began to undergo deliquescence at temperatures above the frost point temperature for pure water ice. Significant water uptake from the atmosphere began to occur within minutes, indicating that bulk deliquescence is likely to occur on present-day Mars. This demonstrates that perchlorates in the surface material can contribute to the hydrological cycle on Mars by absorbing water directly from the atmosphere. Chamber experiments have also been conducted to study adsorption of water on regolith grains. Raman spectroscopy has been applied to study the adsorption properties of zeolites under conditions found at the Phoenix landing site on Mars. Preliminary experimental results indicate that zeolites on the surface of Mars are capable of adsorbing water from the atmosphere on diurnal time scales and that Raman spectroscopy provides a promising method for detecting this process during a landed mission.

  11. GPS water vapor and its comparison with radiosonde and ERA-Interim data in Algeria

    Science.gov (United States)

    Namaoui, Houaria; Kahlouche, Salem; Belbachir, Ahmed Hafid; Van Malderen, Roeland; Brenot, Hugues; Pottiaux, Eric

    2017-05-01

    Remote sensing of atmospheric water vapor using global positioning system (GPS) data has become an effective tool in meteorology, weather forecasting and climate research. This paper presents the estimation of precipitable water (PW) from GPS observations and meteorological data in Algeria, over three stations located at Algiers, Bechar and Tamanrasset. The objective of this study is to analyze the sensitivity of the GPS PW estimates for the three sites to the weighted mean temperature ( T m), obtained separately from two types of T m- T s regression [one general, and one developed specifically for Algeria ( T s stands for surface temperature)], and calculated directly from ERA-Interim data. The results show that the differences in T m are of the order of 18 K, producing differences of 2.01 mm in the final evaluation of PW. A good agreement is found between GPS-PW and PW calculated from radiosondes, with a small mean difference with Vaisala radiosondes. A comparison between GPS and ERA-Interim shows a large difference (4 mm) in the highlands region. This difference is possibly due to the topography. These first results are encouraging, in particular for meteorological applications in this region, with good hope to extend our dataset analysis to a more complete, nationwide coverage over Algeria.

  12. The influence of methanol addition during the film growth of SnO 2 by atmospheric pressure chemical vapor deposition

    NARCIS (Netherlands)

    Volintiru, I.; Graaf, A. de; Deelen, J. van; Poodt, P.W.G.

    2011-01-01

    Undoped tin oxide (SnO2) thin films have been deposited in a stagnant point flow chemical vapor deposition reactor from a water/tin tetrachloride mixture. By adding methanol during the deposition process the film electrical properties change significantly: ten times more conductive SnO 2 films are

  13. Reduction of Legionella spp. in Water and in Soil by a Citrus Plant Extract Vapor

    Science.gov (United States)

    Kurzbach, Elena; Score, Jodie; Tejpal, Jyoti; Chi Tangyie, George; Phillips, Carol

    2014-01-01

    Legionnaires' disease is a severe form of pneumonia caused by Legionella spp., organisms often isolated from environmental sources, including soil and water. Legionella spp. are capable of replicating intracellularly within free-living protozoa, and once this has occurred, Legionella is particularly resistant to disinfectants. Citrus essential oil (EO) vapors are effective antimicrobials against a range of microorganisms, with reductions of 5 log cells ml−1 on a variety of surfaces. The aim of this investigation was to assess the efficacy of a citrus EO vapor against Legionella spp. in water and in soil systems. Reductions of viable cells of Legionella pneumophila, Legionella longbeachae, Legionella bozemanii, and an intra-amoebal culture of Legionella pneumophila (water system only) were assessed in soil and in water after exposure to a citrus EO vapor at concentrations ranging from 3.75 mg/liter air to 15g/liter air. Antimicrobial efficacy via different delivery systems (passive and active sintering of the vapor) was determined in water, and gas chromatography-mass spectrometry (GC-MS) analysis of the antimicrobial components (linalool, citral, and β-pinene) was conducted. There was up to a 5-log cells ml−1 reduction in Legionella spp. in soil after exposure to the citrus EO vapors (15 mg/liter air). The most susceptible strain in water was L. pneumophila, with a 4-log cells ml−1 reduction after 24 h via sintering (15 g/liter air). Sintering the vapor through water increased the presence of the antimicrobial components, with a 61% increase of linalool. Therefore, the appropriate method of delivery of an antimicrobial citrus EO vapor may go some way in controlling Legionella spp. from environmental sources. PMID:25063652

  14. Reduction of Legionella spp. in water and in soil by a citrus plant extract vapor.

    Science.gov (United States)

    Laird, Katie; Kurzbach, Elena; Score, Jodie; Tejpal, Jyoti; Chi Tangyie, George; Phillips, Carol

    2014-10-01

    Legionnaires' disease is a severe form of pneumonia caused by Legionella spp., organisms often isolated from environmental sources, including soil and water. Legionella spp. are capable of replicating intracellularly within free-living protozoa, and once this has occurred, Legionella is particularly resistant to disinfectants. Citrus essential oil (EO) vapors are effective antimicrobials against a range of microorganisms, with reductions of 5 log cells ml(-1) on a variety of surfaces. The aim of this investigation was to assess the efficacy of a citrus EO vapor against Legionella spp. in water and in soil systems. Reductions of viable cells of Legionella pneumophila, Legionella longbeachae, Legionella bozemanii, and an intra-amoebal culture of Legionella pneumophila (water system only) were assessed in soil and in water after exposure to a citrus EO vapor at concentrations ranging from 3.75 mg/liter air to 15g/liter air. Antimicrobial efficacy via different delivery systems (passive and active sintering of the vapor) was determined in water, and gas chromatography-mass spectrometry (GC-MS) analysis of the antimicrobial components (linalool, citral, and β-pinene) was conducted. There was up to a 5-log cells ml(-1) reduction in Legionella spp. in soil after exposure to the citrus EO vapors (15 mg/liter air). The most susceptible strain in water was L. pneumophila, with a 4-log cells ml(-1) reduction after 24 h via sintering (15 g/liter air). Sintering the vapor through water increased the presence of the antimicrobial components, with a 61% increase of linalool. Therefore, the appropriate method of delivery of an antimicrobial citrus EO vapor may go some way in controlling Legionella spp. from environmental sources. Copyright © 2014, American Society for Microbiology. All Rights Reserved.

  15. Correlation of vapor - liquid equilibrium data for acetic acid - isopropanol - water - isopropyl acetate mixtures

    Directory of Open Access Journals (Sweden)

    B. A. Mandagarán

    2006-03-01

    Full Text Available A correlation procedure for the prediction of vapor - liquid equilibrium of acetic acid - isopropanol - water - isopropyl acetate mixtures has been developed. It is based on the NRTL model for predicting liquid activity coefficients, and on the Hayden-O'Connell second virial coefficients for predicting the vapor phase of systems containing association components. When compared with experimental data the correlation shows a good agreement for binary and ternary data. The correlation also shows good prediction for reactive quaternary data.

  16. Vaporization order and burning efficiency of crude oils during in-situ burning on water

    DEFF Research Database (Denmark)

    van Gelderen, Laurens; Malmquist, Linus M.V.; Jomaas, Grunde

    2017-01-01

    In order to improve the understanding of the burning efficiency and its observed size dependency of in-situ burning of crude oil on water, the vaporization order of the components in crude oils was studied. The vaporization order of such multicomponent fuels was assessed by studying the surface...... scale fires can overcome these heat losses, as they typically have higher burning rates, which increase the heat feedback to the fuel surface and therefore can result in the higher burning efficiencies....

  17. Long-Term Uptake of Phenol-Water Vapor Follows Similar Sigmoid Kinetics on Prehydrated Organic Matter- and Clay-Rich Soil Sorbents.

    Science.gov (United States)

    Borisover, Mikhail; Bukhanovsky, Nadezhda; Lado, Marcos

    2017-09-19

    Typical experimental time frames allowed for equilibrating water-organic vapors with soil sorbents might lead to overlooking slow chemical reactions finally controlling a thermodynamically stable state. In this work, long-term gravimetric examination of kinetics covering about 4000 h was performed for phenol-water vapor interacting with four materials pre-equilibrated at three levels of air relative humidity (RHs 52, 73, and 92%). The four contrasting sorbents included an organic matter (OM)-rich peat soil, an OM-poor clay soil, a hydrophilic Aldrich humic acid salt, and water-insoluble leonardite. Monitoring phenol-water vapor interactions with the prehydrated sorbents, as compared with the sorbent samples in phenol-free atmosphere at the same RH, showed, for the first time, a sigmoid kinetics of phenol-induced mass uptake typical for second-order autocatalytic reactions. The apparent rate constants were similar for all the sorbents, RHs and phenol activities studied. A significant part of sorbed phenol resisted extraction, which was attributed to its abiotic oxidative coupling. Phenol uptake by peat and clay soils was also associated with a significant enhancement of water retention. The delayed development of the sigmoidal kinetics in phenol-water uptake demonstrates that long-run abiotic interactions of water-organic vapor with soil may be overlooked, based on short-term examination.

  18. Effects of biochar and manure amendments on water vapor sorption in a sandy loam soil

    DEFF Research Database (Denmark)

    Arthur, Emmanuel; Tuller, Markus; Moldrup, Per

    2015-01-01

    properties of soils, especially on water retention at low matric potentials. To overcome this knowledge gap, the effects of combined BC (0 to 100 Mg ha-1) and manure (21 and 42 Mg ha-1) applications on water vapor sorption and specific surface area was investigated for a sandy loam soil. In addition......, potential impacts of BC aging were evaluated. All considered BC-amendment rates led to a distinct increase of water retention, especially for low matric potentials. The observed increases were attributed to a significant increase of soil organic matter contents and specific surface areas in BCamended soils....... Hysteresis of the water vapor sorption isotherms increased with increasing BC application rates. Biochar age did not significantly affect vapor sorption and SSA....

  19. Water vapor permeation and dehumidification performance of poly(vinyl alcohol)/lithium chloride composite membranes

    KAUST Repository

    Bui, Duc Thuan

    2015-10-09

    Thin and robust composite membranes comprising stainless steel scaffold, fine and porous TiO2 and polyvinyl alcohol/lithium chloride were fabricated and studied for air dehumidification application. Higher hydrophilicity, sorption and permeation were observed for membranes with increased lithium chloride content up to 50%. The permeation and sorption properties of the membranes were investigated under different temperatures. The results provided a deeper insight into the membrane water vapor permeation process. It was specifically noted that lithium chloride significantly reduces water diffusion energy barrier, resulting in the change of permeation energy from positive to negative values. Higher water vapor permeance was observed for the membrane with higher LiCl content at lower temperature. The isothermal air dehumidification tests show that the membrane is suitable for dehumidifying air in high humid condition. Additionally, results also indicate a trade-off between the humidity ratio drop with the water vapor removal rate when varying air flowrate.

  20. Determining Atmospheric Pressure Using a Water Barometer

    Science.gov (United States)

    Lohrengel, C. Frederick, II; Larson, Paul R.

    2012-01-01

    The atmosphere is an envelope of compressible gases that surrounds Earth. Because of its compressibility and nonuniform heating by the Sun, it is in constant motion. The atmosphere exerts pressure on Earth's surface, but that pressure is in constant flux. This experiment allows students to directly measure atmospheric pressure by measuring the…

  1. Study of the effect of water vapor on a resistive plate chamber with glass electrodes

    CERN Document Server

    Sakai, H H; Teramoto, Y; Nakano, E E; Takahashi, T T

    2002-01-01

    We studied the effects of water vapor on the efficiencies of resistive plate chambers with glass electrodes, operated in the streamer mode. With moisture in the chamber gas that has freon as a component (water vapor approx 1000 ppm), a decrease in the efficiency (approx 20%) has been observed after operating for a period of several weeks to a few months. From our study, the cause of the efficiency decrease was identified as a change on the cathode surface. In addition, a recovery method was found: flushing for 1 day with argon bubbled through water containing >=3% ammonia, followed by a few weeks of training with dry gas.

  2. Impact of freeze-drying, mixing and horizontal transport on water vapor in the upper troposphere and lower stratosphere (UTLS)

    Science.gov (United States)

    Poshyvailo, Liubov; Ploeger, Felix; Müller, Rolf; Tao, Mengchu; Konopka, Paul; Abdoulaye Diallo, Mohamadou; Grooß, Jens-Uwe; Günther, Gebhard; Riese, Martin

    2017-04-01

    Water vapor in the upper troposphere and lower stratosphere (UTLS) is a key player in the global radiation budget. Therefore, a realistic representation of the water vapor distribution in this region and the involved control processes is critical for climate models, but largely uncertain hitherto. It is known that the extremely low temperatures around the tropical tropopause cause the dominant factor controlling water vapor in the lower stratosphere. Here, we focus on additional processes, such as horizontal transport between tropics and extratropics, small-scale mixing, and freeze-drying. We assess the sensitivities of simulated water vapor in the UTLS from simulations with the Chemical Lagrangian Model of the Stratosphere (CLaMS). CLaMS is a Lagrangian transport model, with a parameterization of small-scale mixing (model diffusion) which is coupled to deformations in the large-scale flow. First, to assess the robustness of water vapor with respect to the meteorological datasets we examine CLaMS driven by ECMWF ERA-Interim and the Japanese 55-year reanalysis. Second, to investigate the effects of small-scale mixing we vary the parameterized mixing strength in the CLaMS model between the reference case with the mixing strength optimized to reproduce atmospheric trace gas observations and a purely advective simulation with parameterized mixing turned off. Also calculation of Lagrangian cold points gives further insight of the processes involved. Third, to assess the effects of horizontal transport between the tropics and extratropics we carry out sensitivity simulations with horizontal transport barriers along latitude circles at the equator, 15°N/S and 35°N/S. Finally, the impact of Antarctic dehydration is estimated from additional sensitivity simulations with switched off freeze-drying in the model at high latitudes of 50°N/S. Our results show that the uncertainty in the tropical tropopause temperatures between current reanalysis datasets causes significant

  3. Three dimensional ray tracing technique for tropospheric water vapor tomography using GPS measurements

    Science.gov (United States)

    Haji Aghajany, Saeid; Amerian, Yazdan

    2017-11-01

    Tropospheric water vapor has a key role in tropospheric processes and it is an important parameter in meteorology studies. Because of its non-uniform spatiotemporal distribution, modeling the spatiotemporal variations of water vapor is a challenging subject in meteorology. The GNSS tomography of the troposphere is a promising method to assess the spatiotemporal distribution of water vapor parameter in this layer. The tomography method efficiency is dependent on the ray tracing technique and GPS derived tropospheric slant wet delays. Implementing constraints and regularization methods are necessary in order to achieve the regularized solution in troposphere tomography. In this paper, the three dimensional (3D) ray tracing technique based on Eikonal equations and ERA-I data are used to perform the reconstruction the signal path, Iranian Permanent GPS Network (IPGN) measurements are used to calculate slant wet delays and the LSQR regularization technique is used to obtain a regularized tomographic solution for tropospheric water vapor. The modeled water vapor profiles are validated using radiosonde observations.

  4. Herschel observations of cold water vapor and ammonia in protoplanetary disks

    Science.gov (United States)

    Hogerheijde, Michiel R.; Bergin, Edwin A.; Brinch, Christian; Cleeves, L. Ilsedore; Fogel, Jeffrey K. J.; Blake, Geoffrey A.; Dominik, Carsten; Lis, Dariusz C.; Melnick, Gary; Neufeld, David; Panić, Olja; Pearson, John C.; Kristensen, Lars; Yíldíz, Umut A.; van Dishoeck, Ewine F.

    2012-03-01

    We present the results of a Herschel/HIFI study into the presence of cold water vapor in a sample of protoplanetary disks, carried out as part of the Guaranteed Time Key Program `Water in Star Forming Regions with Herschel' (WISH). While toward most disks only upper limits are obtained, rotational ground-state emission lines of ortho-H_2O and para-H_2O are clearly detected toward the disk of TW Hya. The detection of cold water vapor, extending to at least 115 AU, in this disk indicates the presence of a vast reservoir of water ice totalling ˜ 1028 g or thousands of Earth Oceans. Photodesorption by stellar ultraviolet radiation likely liberates a small amount of water vapor from icy grains. Significant settling of such icy grains toward the disk midplane is required to match the detected amount of water vapor. The water ortho-to-para ratio of 0.77 is significantly different from that observed in Solar System comets where a range of 1.5--3 is found. If this reflects the temperature regime of the water ice (formation), this finding suggests that long-range mixing of volatiles has occured in the Solar Nebula. The same Herschel/HIFI data also detect the emission of NH_3 in TW Hya's disk, and the implications of this finding are discussed.

  5. On-line coating of glass with tin oxide by atmospheric pressure chemical vapor deposition.

    Energy Technology Data Exchange (ETDEWEB)

    Allendorf, Mark D.; Sopko, J.F. (PPF Industries, Pittsburgh, PA); Houf, William G.; Chae, Yong Kee; McDaniel, Anthony H.; Li, M. (PPF Industries, Pittsburgh, PA); McCamy, J.W. (PPF Industries, Pittsburgh, PA)

    2006-11-01

    Atmospheric pressure chemical vapor deposition (APCVD) of tin oxide is a very important manufacturing technique used in the production of low-emissivity glass. It is also the primary method used to provide wear-resistant coatings on glass containers. The complexity of these systems, which involve chemical reactions in both the gas phase and on the deposition surface, as well as complex fluid dynamics, makes process optimization and design of new coating reactors a very difficult task. In 2001 the U.S. Dept. of Energy Industrial Technologies Program Glass Industry of the Future Team funded a project to address the need for more accurate data concerning the tin oxide APCVD process. This report presents a case study of on-line APCVD using organometallic precursors, which are the primary reactants used in industrial coating processes. Research staff at Sandia National Laboratories in Livermore, CA, and the PPG Industries Glass Technology Center in Pittsburgh, PA collaborated to produce this work. In this report, we describe a detailed investigation of the factors controlling the growth of tin oxide films. The report begins with a discussion of the basic elements of the deposition chemistry, including gas-phase thermochemistry of tin species and mechanisms of chemical reactions involved in the decomposition of tin precursors. These results provide the basis for experimental investigations in which tin oxide growth rates were measured as a function of all major process variables. The experiments focused on growth from monobutyltintrichloride (MBTC) since this is one of the two primary precursors used industrially. There are almost no reliable growth-rate data available for this precursor. Robust models describing the growth rate as a function of these variables are derived from modeling of these data. Finally, the results are used to conduct computational fluid dynamic simulations of both pilot- and full-scale coating reactors. As a result, general conclusions are

  6. Canopy Stomatal Conductance Unlocks Partitioning of Ecosystem-Atmosphere Carbon and Water Exchanges

    Science.gov (United States)

    Wehr, R. A.; Munger, J. W.; McManus, J. B.; Nelson, D. D.; Zahniser, M. S.; Davidson, E. A.; Wofsy, S. C.; Saleska, S. R.

    2016-12-01

    Stomata are a key nexus in biosphere-atmosphere interactions: the gateway for both carbon gain and water loss by plant canopies. Accurate quantification of canopy stomatal conductance enables partitioning of both evapotranspiration (ET) and net ecosystem-atmosphere CO2 exchange (NEE)—the latter via CO2 isotope flux measurements. To those ends, we determined the behavior of canopy stomatal conductance in a temperate deciduous forest based on heat and water vapor flux measurements, and validated that determination based on uptake of carbonyl sulfide, which also passes through the stomata. We found that the canopy stomatal conductance followed a simple empirical function of leaf area index, light intensity, diffuse light fraction, and leaf-air water vapor gradient. The dependence on light intensity was highly linear, in contrast to the leaf scale, and in contrast to the behavior of canopy photosynthesis. Using canopy stomatal conductance, we partitioned ET and found that evaporation in this ecosystem peaks at the time of the year when soils are driest and atmospheric vapor pressure deficit is low—because soil temperature is an important driver. As stomatal conductance impacts not only the rate of photosynthesis but also the fractionation of carbon isotopes by photosynthesis, we were also able to combine canopy stomatal conductance with CO2 isotope flux measurements in order to partition NEE. We found that: (1) canopy respiration is much less during the day than at night, likely due to the inhibition of leaf respiration by light (that is, the Kok effect), and (2) canopy photosynthetic light-use efficiency does not decline through the summer, in contrast to standard estimates. These results clarify how leaf-level physiological dynamics impact ecosystem-atmosphere gas exchange, and demonstrate the utility of combining multiple tracers to constrain the processes underlying that exchange.

  7. Validation of MIPAS IMK-IAA Temperature, Water Vapor, and Ozone Profiles with MOHAVE-2009 Campaign Measurements

    Science.gov (United States)

    Stiller, Gabrielle; Kiefer, M.; Eckert, E.; von Clarmann, T.; Kellmann, S.; Garcia-Comas, M.; Funke, B.; Leblanc, T.; Fetzer, E.; Froidevaux, L.; hide

    2012-01-01

    MIPAS observations of temperature, water vapor, and ozone in October 2009 as derived with the scientific level-2 processor run by Karlsruhe Institute of Technology (KIT), Institute for Meteorology and Climate Research (IMK) and CSIC, Instituto de Astrofisica de Andalucia (IAA) and retrieved from version 4.67 level-1b data have been compared to co-located field campaign observations obtained during the MOHAVE-2009 campaign at the Table Mountain Facility near Pasadena, California in October 2009. The MIPAS measurements were validated regarding any potential biases of the profiles, and with respect to their precision estimates. The MOHAVE-2009 measurement campaign provided measurements of atmospheric profiles of temperature, water vapor/relative humidity, and ozone from the ground to the mesosphere by a suite of instruments including radiosondes, ozonesondes, frost point hygrometers, lidars, microwave radiometers and Fourier transform infrared (FTIR) spectrometers. For MIPAS temperatures (version V4O_T_204), no significant bias was detected in the middle stratosphere; between 22 km and the tropopause MIPAS temperatures were found to be biased low by up to 2 K, while below the tropopause, they were found to be too high by the same amount. These findings confirm earlier comparisons of MIPAS temperatures to ECMWF data which revealed similar differences. Above 12 km up to 45 km, MIPAS water vapor (version V4O_H2O_203) is well within 10% of the data of all correlative instruments. The well-known dry bias of MIPAS water vapor above 50 km due to neglect of non-LTE effects in the current retrievals has been confirmed. Some instruments indicate that MIPAS water vapor might be biased high by 20 to 40% around 10 km (or 5 km below the tropopause), but a consistent picture from all comparisons could not be derived. MIPAS ozone (version V4O_O3_202) has a high bias of up to +0.9 ppmv around 37 km which is due to a non-identified continuum like radiance contribution. No further

  8. Validation of MIPAS IMK/IAA temperature, water vapor, and ozone profiles with MOHAVE-2009 campaign measurements

    Directory of Open Access Journals (Sweden)

    G. P. Stiller

    2012-02-01

    Full Text Available MIPAS observations of temperature, water vapor, and ozone in October 2009 as derived with the scientific level-2 processor run by Karlsruhe Institute of Technology (KIT, Institute for Meteorology and Climate Research (IMK and CSIC, Instituto de Astrofísica de Andalucía (IAA and retrieved from version 4.67 level-1b data have been compared to co-located field campaign observations obtained during the MOHAVE-2009 campaign at the Table Mountain Facility near Pasadena, California in October 2009. The MIPAS measurements were validated regarding any potential biases of the profiles, and with respect to their precision estimates. The MOHAVE-2009 measurement campaign provided measurements of atmospheric profiles of temperature, water vapor/relative humidity, and ozone from the ground to the mesosphere by a suite of instruments including radiosondes, ozonesondes, frost point hygrometers, lidars, microwave radiometers and Fourier transform infra-red (FTIR spectrometers. For MIPAS temperatures (version V4O_T_204, no significant bias was detected in the middle stratosphere; between 22 km and the tropopause MIPAS temperatures were found to be biased low by up to 2 K, while below the tropopause, they were found to be too high by the same amount. These findings confirm earlier comparisons of MIPAS temperatures to ECMWF data which revealed similar differences. Above 12 km up to 45 km, MIPAS water vapor (version V4O_H2O_203 is well within 10% of the data of all correlative instruments. The well-known dry bias of MIPAS water vapor above 50 km due to neglect of non-LTE effects in the current retrievals has been confirmed. Some instruments indicate that MIPAS water vapor might be biased high by 20 to 40% around 10 km (or 5 km below the tropopause, but a consistent picture from all comparisons could not be derived. MIPAS ozone (version V4O_O3_202 has a high bias of up to +0.9 ppmv around 37 km which is due to a non-identified continuum like radiance contribution

  9. Three dimensional water vapor distribution based on InSAR data during the heavy rain over Shizuoka on 3 July 2008

    Science.gov (United States)

    Kinoshita, Y.; Furuya, M.

    2012-12-01

    Interferometric synthetic aperture radar (InSAR) is a technique for mapping the phase difference between two observations and used for detecting ground deformation associated with, for instace, earthquakes and volcanic activities. Like GPS, the phase signal in InSAR is affected by the earth's atmosphere which has a different refractive index relative to vacuum. In the neutral atmosphere, water vapor has the largest impact for InSAR phase signals due to its spatiotemporal heterogeneity. However, we can take advantage of this to detect an extremely detailed spatial distribution of precipitable water vapor in the absence of any ground displacements. On 3-4 July 2008, a heavy rain battered Shizuoka prefecture, the east side of Tokai region. The Advanced Land Observing Satellite (ALOS) Phased Array type L-band Synthetic Aperture Radar (PALSAR) observed this area on 3 July 2008, and the interferogram obtained from that PALSAR data contained the localized signal near Mishima city, the horizontal width of which is on the order of 10 km and the amplitude reached 15 cm in radar line-of-sight. In the weather radar data, there was the strong echo equivalent to 80 mm per an hour in the west-southwest of the localized signal in the interferogram. Comparing this with other interferograms over the same region, we verified that the localized signal is not due to any ground displacements, but due to water vapor in the troposphere. Here we estimated three dimensional water vapor distribution during the heavy rain based on the interferogram including the water vapor-derived localized delay signal with the ray tracing method (Hobiger et al., 2008). The three dimensional refractivity field is a function of dry air density, temperature and water vapor density (Aparicio and Laroche, 2011), and is needed to estimate the delay amount by ray tracing. In this study, we first put values of dry air density and temperature which are spatially less variable to that of Mesoscale Model (MSM) data

  10. Roughness Length of Water Vapor over Land Surfaces and Its Influence on Latent Heat Flux

    Directory of Open Access Journals (Sweden)

    Sang-Jong Park

    2010-01-01

    Full Text Available Latent heat flux at the surface is largely dependent on the roughness length for water vapor (z0q. The determination of z0q is still uncertain because of its multifaceted characteristics of surface properties, atmospheric conditions and insufficient observations. In this study, observed values from the Fluxes Over Snow Surface II field experiment (FLOSS-II from November 2002 to March 2003 were utilized to estimate z0q over various land surfaces: bare soil, snow, and senescent grass. The present results indicate that the estimated z0q over bare soil is much smaller than the roughness length of momentum (z0m; thus, the ratio z0m/z0q is larger than those of previous studies by a factor of 20 - 150 for the available flow regime of the roughness Reynolds number, Re* > 0.1. On the snow surface, the ratio is comparable to a previous estimation for the rough flow (Re* > 1, but smaller by a factor of 10 - 50 as the flow became smooth (Re* < 1. Using the estimated ratio, an optimal regression equation of z0m/z0q is determined as a function of Re* for each surface type. The present parameterization of the ratio is found to greatly reduce biases of latent heat flux estimation compared with that estimated by the conventional method, suggesting the usefulness of current parameterization for numerical modeling.

  11. Pebax®1657/Graphene oxide composite membranes for improved water vapor separation

    KAUST Repository

    Akhtar, Faheem Hassan

    2016-11-02

    In this study composite mixed matrix membranes containing hydrophilic microphase-separated block copolymer (Pebax® 1657) and graphene oxide nanosheets were prepared using a dip coating method. Water vapor and N2 gas permeation were measured as a function of different parameters: (i) layer thickness, (ii) content of graphene oxide (GO), and (iii) content of reduced GO. Surprisingly, a concentration of only 2 wt% of GO nanosheets well dispersed in the Pebax layer boosted the selectivity 8 times by decreasing the water vapor permeance by only 12% whereas N2 gas permeance decreased by 70%. Using reduced GO instead, the water vapor permeance declined by up to 16% with no influence on the N2 gas permeance. We correlated the permeation properties of the mixed matrix membranes with different models and found, that both the modified Nielsen model and the Cussler model give good correlation with experimental findings.

  12. Spatio-Temporal Analysis of MODIS Retrieved Precipitable Water Vapor over Urban and Rural Areas in the Philippines

    Science.gov (United States)

    Galvez, M. C. D.; Castilla, R. M.; Catenza, J. L. U.; Soronio, H.; Vallar, E. A.

    2016-12-01

    Precipitable water vapor (PWV) is a component of the atmosphere that significantly influences many atmospheric processes. It plays a dominant role in the high-energy thermodynamics of the atmosphere, notably, the genesis of storm systems. Remote sensing of the atmosphere using MODerate resolution Imaging Spectroradiometer (MODIS) offers a relatively inexpensive method to estimate atmospheric water vapour in the form of columnar measurements from its 936 nm near-infrared band. Daily Level 3 data with 1 degree grid spatial resolution from MODIS was used in order to determine the temporal and spatial variability of precipitable water between urban and rural areas in the Philippines. The PWV values were rasterized and spatially interpolated to be stored in a 1 kilometer grid resolution using the nearest-neighbor algorithm. General Linear Models were established to determine the main and interaction effects on PWV values of several categorical factors e.g. time, administrative region, and geographic classification. Comparison between the urban and rural areas in the Philippines showed that there is a significant difference between the values between these demographic dimensions. The mean PWV in the urban areas was found to be 0.0473 cm greater than the mean PWV of the rural areas. Lower levels of precipitable water vapour in rural places can be attributed to the low humidity as a result of a deficit of precipitation; while higher levels in urban areas can be accounted for by vehicle exhaust, industrial emissions, and irrigation of parks and gardens. In general, PWV varies depending on the season when solar insolation affects surface temperature, thus influencing the rate of evaporation. Using the regression line algorithm, the PWV values for rural areas have increased to 0.904 cm and 0.434 cm for urban areas from the year 2005 to 2015.

  13. Experimental Research on Water Boiling Heat Transfer on Horizontal Copper Rod Surface at Sub-Atmospheric Pressure

    Directory of Open Access Journals (Sweden)

    Li-Hua Yu

    2015-09-01

    Full Text Available In recent years, water (R718 as a kind of natural refrigerant—which is environmentally-friendly, safe and cheap—has been reconsidered by scholars. The systems of using water as the refrigerant, such as water vapor compression refrigeration and heat pump systems run at sub-atmospheric pressure. So, the research on water boiling heat transfer at sub-atmospheric pressure has been an important issue. There are many research papers on the evaporation of water, but there is a lack of data on the characteristics at sub-atmospheric pressures, especially lower than 3 kPa (the saturation temperature is 24 °C. In this paper, the experimental research on water boiling heat transfer on a horizontal copper rod surface at 1.8–3.3 kPa is presented. Regression equations of the boiling heat transfer coefficient are obtained based on the experimental data, which are convenient for practical application.

  14. Membrane-assisted vapor stripping: energy efficient hybrid distillation-vapor permeation process for alcohol-water separation

    Science.gov (United States)

    BACKGROUND: Energy efficient alternatives to distillation for alcohol recovery from dilute solution are needed to improve biofuel sustainability. A process integrating steam stripping with a vapor compression step and a vapor permeation membrane separation step is proposed. The...

  15. Water Repellence and Oxygen and Water Vapor Barrier of PVOH-Coated Substrates before and after Surface Esterification

    Directory of Open Access Journals (Sweden)

    Markus Schmid

    2014-11-01

    Full Text Available This study investigates chemical grafting with fatty acid chlorides as a method for the surface modification of hydrophilic web materials. The resulting changes in the water repellence and barrier properties were studied. For this purpose, different grades of polyvinyl alcohol (PVOH were coated on regenerated cellulose films (“cellophane” and paper and then grafted with fatty acid chlorides. The PVOH grades varied in their degree of hydrolysis and average molecular weight. The surface was esterified with two fatty acid chlorides, palmitoyl (C16 and stearoyl chloride (C18, by chemical grafting. The chemical grafting resulted in water-repellent surfaces and reduced water vapor transmission rates by a factor of almost 19. The impact of the surface modification was greater for a higher degree of hydrolysis of the polyvinyl alcohol and for shorter fatty acid chains. Although the water vapor barrier for palmitoyl-grafted PVOH was higher than for stearoyl-grafted PVOH, the contact angle with water was lower. Additionally, it was shown that a higher degree of hydrolysis led to higher water vapor barrier improvement factors after grafting. Furthermore, the oxygen permeability decreased after grafting significantly, due to the fact that the grafting protects the PVOH against humidity when the humidity is applied on the grafted side. It can be concluded that the carbon chain length of the fatty acid chlorides is the limiting factor for water vapor adsorption, but the grafting density is the bottleneck for water diffusing in the polymer.

  16. Simultaneous Water Vapor and Dry Air Optical Path Length Measurements and Compensation with the Large Binocular Telescope Interferometer

    Science.gov (United States)

    Defrere, D.; Hinz, P.; Downey, E.; Boehm, M.; Danchi, W. C.; Durney, O.; Ertel, S.; Hill, J. M.; Hoffmann, W. F.; Mennesson, B.; hide

    2016-01-01

    The Large Binocular Telescope Interferometer uses a near-infrared camera to measure the optical path length variations between the two AO-corrected apertures and provide high-angular resolution observations for all its science channels (1.5-13 microns). There is however a wavelength dependent component to the atmospheric turbulence, which can introduce optical path length errors when observing at a wavelength different from that of the fringe sensing camera. Water vapor in particular is highly dispersive and its effect must be taken into account for high-precision infrared interferometric observations as described previously for VLTI/MIDI or the Keck Interferometer Nuller. In this paper, we describe the new sensing approach that has been developed at the LBT to measure and monitor the optical path length fluctuations due to dry air and water vapor separately. After reviewing the current performance of the system for dry air seeing compensation, we present simultaneous H-, K-, and N-band observations that illustrate the feasibility of our feed forward approach to stabilize the path length fluctuations seen by the LBTI nuller uses a near-infrared camera to measure the optical path length variations between the two AO-corrected apertures and provide high-angular resolution observations for all its science channels (1.5-13 microns). There is however a wavelength dependent component to the atmospheric turbulence, which can introduce optical path length errors when observing at a wavelength different from that of the fringe sensing camera. Water vapor in particular is highly dispersive and its effect must be taken into account for high-precision infrared interferometric observations as described previously for VLTI MIDI or the Keck Interferometer Nuller. In this paper, we describe the new sensing approach that has been developed at the LBT to measure and monitor the optical path length fluctuations due to dry air and water vapor separately. After reviewing the current

  17. Water vapor and gas transport through PEO PBT block copolymers

    NARCIS (Netherlands)

    Metz, S.J.; Potreck, Jens; Mulder, M.H.V.; Wessling, Matthias

    2002-01-01

    Introduction At the bore well natural gas is saturated with water. Downstream the presence of water may cause: formation of methane hydrates (blocking eventually the pipeline), condensation of water in the pipeline and corrosion effects. A process used for the dehydration of natural gas is glycol

  18. Photocured epoxy/graphene nanocomposites with enhanced water vapor barrier properties

    Energy Technology Data Exchange (ETDEWEB)

    Periolatto, M.; Spena, P. Russo [Faculty of Science and Technology, Free University of Bozen-Bolzano, Piazza Università 5, Bolzano (Italy); Sangermano, M. [Dipartimento di Scienza Applicata e Tecnologia, Politecnico di Torino, C.so Duca degli Abruzzi 24, Torino (Italy)

    2016-05-18

    A transparent, water vapor barrier film made of an epoxy resin and graphene oxide (GO) was synthesized by photopolymerization process. The epoxy/GO film with just 0.05 wt% GO gives a 93% WVTR reduction with respect to the pristine polymer, reaching barrier properties better than other polymer composites containing higher amounts of graphene. The excellent water vapor barrier is attributed to the good dispersion of GO in the polymer matrix. Moreover, GO significantly enhances the toughness and the damping capacity of the epoxy resins. The hybrid film can have potential applications in anticorrosive coatings, electronic devices, pharmaceuticals and food packaging.

  19. Water Vapor Desorption Characteristics of Honeycomb Type Sorption Element Composed of Organic Sorbent

    Science.gov (United States)

    Inaba, Hideo; Kida, Takahisa; Horibe, Akihiko; Kaneda, Makoto; Okamoto, Tamio; Seo, Jeong-Kyun

    This paper describes the water vapor desorption characteristics of honeycomb shape type sorbent element containing new organic sorbent of the bridged complex of sodium polyacrylate. The transient experiments in which the dry air was passed into the honeycomb type sorbent element sorbed water vapor were carried out under various conditions of air velocity, temperature, relative humidity and honeycomb length. The obtained data for desorption process were compared with those for sorption process. Finally, Sherwood number of mass transfer of the organic sorbent for desorption process was derived in terms of Reynolds number, modified Stefan number and non-dimensional honeycomb length.

  20. Simulation of stratospheric water vapor trends: impact on stratospheric ozone chemistry

    Directory of Open Access Journals (Sweden)

    A. Stenke

    2005-01-01

    Full Text Available A transient model simulation of the 40-year time period 1960 to 1999 with the coupled climate-chemistry model (CCM ECHAM4.L39(DLR/CHEM shows a stratospheric water vapor increase over the last two decades of 0.7 ppmv and, additionally, a short-term increase after major volcanic eruptions. Furthermore, a long-term decrease in global total ozone as well as a short-term ozone decline in the tropics after volcanic eruptions are modeled. In order to understand the resulting effects of the water vapor changes on lower stratospheric ozone chemistry, different perturbation simulations were performed with the CCM ECHAM4.L39(DLR/CHEM feeding the water vapor perturbations only to the chemistry part. Two different long-term perturbations of lower stratospheric water vapor, +1 ppmv and +5 ppmv, and a short-term perturbation of +2 ppmv with an e-folding time of two months were applied. An additional stratospheric water vapor amount of 1 ppmv results in a 5–10% OH increase in the tropical lower stratosphere between 100 and 30 hPa. As a direct consequence of the OH increase the ozone destruction by the HOx cycle becomes 6.4% more effective. Coupling processes between the HOx-family and the NOx/ClOx-family also affect the ozone destruction by other catalytic reaction cycles. The NOx cycle becomes 1.6% less effective, whereas the effectiveness of the ClOx cycle is again slightly enhanced. A long-term water vapor increase does not only affect gas-phase chemistry, but also heterogeneous ozone chemistry in polar regions. The model results indicate an enhanced heterogeneous ozone depletion during antarctic spring due to a longer PSC existence period. In contrast, PSC formation in the northern hemisphere polar vortex and therefore heterogeneous ozone depletion during arctic spring are not affected by the water vapor increase, because of the less PSC activity. Finally, this study shows that 10% of the global total ozone decline in the transient model run

  1. Analysis on Characteristics of Radiosonde Bias Using GPS Precipitable Water Vapor

    Directory of Open Access Journals (Sweden)

    Chang-Geun Park

    2010-09-01

    Full Text Available As an observation instrument of the longest record of tropospheric water vapor, radiosonde data provide upper-air pressure (geopotential height, temperature, humidity and wind. However, the data have some well-known elements related to inaccuracy. In this article, radiosonde precipitable water vapor (PWV at Sokcho observatory was compared with global positioning system (GPS PWV during each summertime of year 2007 and 2008 and the biases were calculated. As a result, the mean bias showed negative values regardless of the rainfall occurrence. In addition, on the basis of GPS PWV, the maximum root mean square error (RMSE was 5.67 mm over the radiosonde PWV.

  2. Comparing Stable Water Isotope Variation in Atmospheric Moisture Observed over Coastal Water and Forests

    Science.gov (United States)

    Lai, C. T.; Rambo, J. P.; Welp, L. R.; Bible, K.; Hollinger, D. Y.

    2014-12-01

    Stable oxygen (δ18O) and hydrogen (δD) isotopologues of atmospheric moisture are strongly influenced by large-scale synoptic weather cycles, surface evapotranspiration and boundary layer mixing. Atmospheric water isotope variation has been shown to empirically relate to relative humidity (Rh) of near surface moisture, and to a less degree, air temperature. Continuous δ18O and δD measurements are becoming more available, providing new opportunities to investigate processes that control isotope variability. This study shows the comparison of δ18O and δD measured at a continental location and over coastal waters for 3 seasons (spring to fall, 2014). The surface moisture isotope measurements were made using two LGR spectroscopy water vapor isotope analyzers (Los Gatos Research Inc.), one operated in an old-growth coniferous forest at Wind River field station, WA (45.8205°N, 121.9519°W), and another sampling marine air over seawater at the Scripps Pier in San Diego, CA (32.8654°N, 117.2536°W), USA. Isotope variations were measured at 1Hz and data were reported as hourly averages with an overall accuracy of ±0.1‰ for δ18O, ±0.5‰ for δ2H. Day-to-day variations in δ18O and δD are shown strongly influenced by synoptic weather events at both locations. Boundary layer mixing between surface moisture and the dry air entrained from the free troposphere exerts a midday maximum and a consistent diel pattern in deuterium excess (dx). At the forest site, surface moisture also interacts with leaf water through transpiration during the day and re-equilibration at night. The latter occurs by retro-diffusion of atmospheric H2O molecules into leaf intercellular space, which becomes intensified as Rh increaes after nightfall, and continues until sunrise, to counter-balance the evaporative isotopic enrichment in leaf water on a daily basis. These vegetation effects lead to negative dx values consistently observed at nighttime in this continental location that were not

  3. Oxygen source-oriented control of atmospheric pressure chemical vapor deposition of VO2 for capacitive applications

    Directory of Open Access Journals (Sweden)

    Dimitra Vernardou

    2016-06-01

    Full Text Available Vanadium dioxides of different crystalline orientation planes have successfully been fabricated by chemical vapor deposition at atmospheric pressure using propanol, ethanol and O2 gas as oxygen sources. The thick a-axis textured monoclinic vanadium dioxide obtained through propanol presented the best electrochemical response in terms of the highest specific discharge capacity of 459 mAh g-1 with a capacitance retention of 97 % after 1000 scans under constant specific current of 2 A g-1. Finally, the electrochemical impedance spectroscopy indicated that the charge transfer of Li+ through the vanadium dioxide / electrolyte interface was easier for this sample enhancing significantly its capacitance performance.

  4. Seasonal Water Transport in the Atmosphere of Mars: Applications of a Mars General Circulation Model Using Mars Global Surveyor Data

    Science.gov (United States)

    Hollingsworth, Jeffery L.; Bridger, Alison F. C.; Haberle, Robert M.

    1999-01-01

    This is a Final Report for a Joint Research Interchange (JRI) between NASA Ames Research Center and San Jose State University, Department of Meteorology. We present below a summary of progress made during the duration of this JRI. The focus of this JRI has been to investigate seasonal water vapor transport in the atmosphere of Mars and its effects on the planet's present climate. To this end, the primary task has been to adapt a new dynamical processor for the adiabatic tendencies of the atmospheric circulation into the NASA Ames Mars general circulation model (MGCM). Using identical boundary and initial conditions, several comparative tests between the new and old MGCMs have been performed and the nature of the simulated circulations have been diagnosed. With confidence that the updated version of the Ames MGCM produces quite similar mean and eddy circulation statistics, the new climate model is well poised as a tool to pursue fundamental questions related to the spatial and seasonal variations of atmospheric water vapor on Mars, and to explore exchanges of water with non-atmospheric reservoirs and transport within its atmosphere. In particular, the role of surface sources and sinks can be explored, the range of water-vapor saturation altitudes can be investigated, and plausible precipitation mechanisms can be studied, for a range of atmospheric dust loadings. Such future investigations can contribute to a comprehensive study of surface inventories, exchange mechanisms, and the relative importance of atmospheric transport Mars' water cycle. A listing of presentations made and manuscripts submitted during the course of this project is provided.

  5. Response of Earth's Atmosphere to Increases in Solar Flux and Implications for Loss of Water from Venus

    Science.gov (United States)

    Kasting, J. F.; Pollock, J. G.; Ackerman, T. P.

    1985-01-01

    A one dimensional radiative convective model is used to compute temperature and water vapor profiles as functions of solar flux for earthlike atmosphere. The troposphere is assumed to be fully saturated with a moist adiabatic lapse rate, and changes in cloudiness are neglected. Predicted surface temperatures increase monotonically from -1 to 111 C as the solar flux is increased from 0.81 to 1.45 times its present value. The results imply that the surface temperature of a primitive water rich Venus should have been at least 80-100 C and may have been much higher, water vapor should have been a major atmospheric constituent at all altitudes, leading to the rapid hydrodynamic escape of hydrogen. The oxygen left behind by this process was presumably consumed by reactions with reduced minerals in the crust.

  6. Modeling of a water vapor selective membrane unit to increase the energy efficiency of humidity harvesting

    Science.gov (United States)

    Bergmair, D.; Metz, S. J.; de Lange, H. C.; van Steenhoven, A. A.

    2012-11-01

    Air humidity is a promising source of clean and safe drinking water. However, in conventional systems a lot of energy is wasted on the production of cold air, rather than the condensation of water vapor. This study examines the possibility of using a hollow fiber membrane module to make this process more energy efficient, by separating the vapor from other gases, prior to the cooling process with the help of selective membranes. The water vapor concentration within a fiber has been modeled using a random walker approach, and the membrane permeability has been implemented as a re-bounce probability for simulation particles interacting with the membrane. Considering the additional work requirement for driving a feed flow through the membrane section and the computed water vapor permeation it could be shown that the energy demand per unit water is lowest for slow flow speeds and favors short and thin fibers. The total energy requirement was estimated to be less than half of the conventional one. Comparison with other CFD simulations and a real life module has shown a good level of agreement, indicating that a membrane section could improve the energy efficiency of humidity harvesting significantly.

  7. Deuterium excess in subtropical free troposphere water vapor: Continuous measurements from the Chajnantor Plateau, northern Chile

    Science.gov (United States)

    Samuels-Crow, Kimberly E.; Galewsky, Joseph; Sharp, Zachary D.; Dennis, Kate J.

    2014-12-01

    Water vapor measured continuously by cavity ring-down spectroscopy from July 2012 to March 2013 on the hyperarid Chajnantor Plateau, northern Chile (elevation = 5080 m, pressure ≈ 550 hPa), has a mean deuterium excess (d-excess = δD - 8*δ18O) of 46‰ ± 5‰ and frequently exceeds 100‰ at low water vapor mixing ratios (q ≤ 500 ppmv). These measurements provide empirical support for theoretical predictions of free troposphere d-excess. The d-excess measured at this site can be understood in terms of supersaturation with respect to ice at relative humidities between 100% and 130%, followed by mixing with moist midtropospheric or lower tropospheric air en route to the plateau. The d-excess measured at Chajnantor is consistent with predictions for d-excess in the upper troposphere from isotope-enabled general circulation models and with high vapor saturation over ice in cloud-resolving and microphysical models.

  8. Eggshell permeability: a standard technique for determining interspecific rates of water vapor conductance.

    Science.gov (United States)

    Portugal, Steven J; Maurer, Golo; Cassey, Phillip

    2010-01-01

    Typically, eggshell water vapor conductance is measured on whole eggs, freshly collected at the commencement of a study. At times, however, it may not be possible to obtain whole fresh eggs but rather egg fragments or previously blown eggs. Here we evaluate and describe in detail a technique for modern laboratory analysis of eggshell conductance that uses fragments from fresh and museum eggs to determine eggshell water vapor conductance. We used fresh unincubated eggs of domesticated chickens (Gallus gallus domesticus), ducks (Anas platyrhynchos domesticus), and guinea fowl (Numida meleagris) to investigate the reliability, validity, and repeatability of the technique. To assess the suitability of museum samples, museum and freshly collected black-headed gull eggs (Larus ridibundus) were used. Fragments were cut out of the eggshell from the blunt end (B), equator (E), and pointy end (P). Eggshell fragments were glued to the top of a 0.25-mL micro test tube (Eppendorf) filled with 200 μL of distilled water and placed in a desiccator at 25°C. Eppendorfs were weighed three times at 24-h intervals, and mass loss was assumed to be a result of water evaporation. We report the following results: (1) mass loss between weighing sessions was highly repeatable and consistent in all species; (2) the majority of intraspecific variability in eggshell water vapor conductance between different eggs of the same species was explained through the differences in water vapor conductance between the three eggshell parts of the same egg (B, E, and P); (3) the technique was sensitive enough to detect significant differences between the three domestic species; (4) there was no overall significant difference between water vapor conductance of museum and fresh black-headed gull eggs; (5) there was no significant difference in water vapor conductance for egg fragments taken from the same egg both between different trials and within the same trial. We conclude, therefore, that this technique

  9. Eddy Covariance measurements of stable isotopes (δD and δ18O) in water vapor

    Science.gov (United States)

    Braden-Behrens, Jelka; Knohl, Alexander

    2017-04-01

    Stable isotopes are a promising tool to enhance our understanding of ecosystem gas exchanges. Studying 18O and 2H in water vapour (H2Ov) can e.g. help partitioning evapotranspiration into its components. With recent developments in laser spectroscopy direct Eddy Covariance (EC) measurements for investigating fluxes of stable isotopologues became feasible. So far very few case studies have applied the EC method to measure stable isotopes in water vapor. We continuously measure fluxes of water vapor isotopologues with the EC method in a managed beech forest in Thuringia, Germany, since autumn 2015 using the following setup: An off-axis integrated cavity output water vapor isotope analyzer (WVIA, Los Gatos Research. Inc, USA) measures the water vapour concentration and its isotopic composition (δD and δ18O). The instrument, that was optimized for high flow rates (app. 4slpm) to generate high frequency (2Hz) measurements, showed sufficient precision with Allan Deviations of app. 0.12 ‰ for δD and 0.06 ‰ for δ18O for averaging periods of 100s. The instrument was calibrated hourly using a high-flow optimized version of the water vapor isotope standard source (WVISS, Los Gatos Research. Inc, USA) that provides water vapor with known isotopic composition for a large range of different concentrations. Our calibration scheme includes a near continuous concentration range calibration instead of a simple 2 or 3-point calibration to face the analyzers strong concentration dependency within a range of app. 6 000 to 16 000 ppm in winter and app. 8 000 to 23 000 ppm in summer. In the used setup, the high-flow and high-frequency optimized water vapor isotope analyzer (WVIA) showed suitable characteristics (Allan deviation and spectral energy distribution) to perform Eddy covariance measurements of stable isotopes in H2Ov. Thus, this novel instrument for EC measurements of water vapor isotopologues provides a new opportunity for studying the hydrological cycle in long

  10. FIRST DETECTION OF WATER VAPOR IN A PRE-STELLAR CORE

    Energy Technology Data Exchange (ETDEWEB)

    Caselli, Paola; Douglas, Thomas [School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT (United Kingdom); Keto, Eric [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Bergin, Edwin A. [Department of Astronomy, The University of Michigan, 500 Church Street, Ann Arbor, MI 48109-1042 (United States); Tafalla, Mario [Observatorio Astronomico Nacional (IGN), Calle Alfonso XII, 3, E-28014 Madrid (Spain); Aikawa, Yuri [Department of Earth and Planetary Sciences, Kobe University, Nada, 657-8501 Kobe (Japan); Pagani, Laurent [LERMA and UMR 8112 du CNRS, Observatoire de Paris, 61 Av. de l' Observatoire, F-75014 Paris (France); Yildiz, Umut A.; Kristensen, Lars E.; Van Dishoeck, Ewine F. [Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden (Netherlands); Van der Tak, Floris F. S. [SRON Netherlands Institute for Space Research, P.O. Box 800, 9700 AV, Groningen (Netherlands); Walmsley, C. Malcolm; Codella, Claudio [INAF-Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, I-50125 Firenze (Italy); Nisini, Brunella, E-mail: p.caselli@leeds.ac.uk [INAF-Osservatorio Astronomico di Roma, I-00040 Monte Porzio Catone (Italy)

    2012-11-10

    Water is a crucial molecule in molecular astrophysics as it controls much of the gas/grain chemistry, including the formation and evolution of more complex organic molecules in ices. Pre-stellar cores provide the original reservoir of material from which future planetary systems are built, but few observational constraints exist on the formation of water and its partitioning between gas and ice in the densest cores. Thanks to the high sensitivity of the Herschel Space Observatory, we report on the first detection of water vapor at high spectral resolution toward a dense cloud on the verge of star formation, the pre-stellar core L1544. The line shows an inverse P-Cygni profile, characteristic of gravitational contraction. To reproduce the observations, water vapor has to be present in the cold and dense central few thousand AU of L1544, where species heavier than helium are expected to freeze out onto dust grains, and the ortho:para H{sub 2} ratio has to be around 1:1 or larger. The observed amount of water vapor within the core (about 1.5 Multiplication-Sign 10{sup -6} M{sub Sun }) can be maintained by far-UV photons locally produced by the impact of galactic cosmic rays with H{sub 2} molecules. Such FUV photons irradiate the icy mantles, liberating water vapor in the core center. Our Herschel data, combined with radiative transfer and chemical/dynamical models, shed light on the interplay between gas and solids in dense interstellar clouds and provide the first measurement of the water vapor abundance profile across the parent cloud of a future solar-type star and its potential planetary system.

  11. First Detection of Water Vapor in a Pre-stellar Core

    Science.gov (United States)

    Caselli, Paola; Keto, Eric; Bergin, Edwin A.; Tafalla, Mario; Aikawa, Yuri; Douglas, Thomas; Pagani, Laurent; Yíldíz, Umut A.; van der Tak, Floris F. S.; Walmsley, C. Malcolm; Codella, Claudio; Nisini, Brunella; Kristensen, Lars E.; van Dishoeck, Ewine F.

    2012-11-01

    Water is a crucial molecule in molecular astrophysics as it controls much of the gas/grain chemistry, including the formation and evolution of more complex organic molecules in ices. Pre-stellar cores provide the original reservoir of material from which future planetary systems are built, but few observational constraints exist on the formation of water and its partitioning between gas and ice in the densest cores. Thanks to the high sensitivity of the Herschel Space Observatory, we report on the first detection of water vapor at high spectral resolution toward a dense cloud on the verge of star formation, the pre-stellar core L1544. The line shows an inverse P-Cygni profile, characteristic of gravitational contraction. To reproduce the observations, water vapor has to be present in the cold and dense central few thousand AU of L1544, where species heavier than helium are expected to freeze out onto dust grains, and the ortho:para H2 ratio has to be around 1:1 or larger. The observed amount of water vapor within the core (about 1.5 × 10-6 M ⊙) can be maintained by far-UV photons locally produced by the impact of galactic cosmic rays with H2 molecules. Such FUV photons irradiate the icy mantles, liberating water vapor in the core center. Our Herschel data, combined with radiative transfer and chemical/dynamical models, shed light on the interplay between gas and solids in dense interstellar clouds and provide the first measurement of the water vapor abundance profile across the parent cloud of a future solar-type star and its potential planetary system.

  12. Infrared characteristic radiation of water condensation and freezing in connection with atmospheric phenomena; Part 3: Experimental data

    Science.gov (United States)

    Tatartchenko, V.; Liu, Yifan; Chen, Wenyuan; Smirnov, P.

    2012-09-01

    This paper is the third one from the series of papers with the same titles published in this journal. The papers consider the infrared characteristic radiation (IRCR) during the first order phase transitions of water: crystallization, water vapor condensation, and water vapor deposition. Experimental results are analyzed in terms of their correspondence to the theoretical model. This model is based on the assertion that the particle's (atom, molecule, or cluster) transition from the higher energetic level in a metastable phase (vapor or liquid) to a lower level in a stable phase (liquid or crystal) produces an emission of one or more photons. The energy of these photons depends on the latent energy of the phase transition and the character of bonds formed by the particle in the new phase. For all investigated substances, this energy falls in the infrared range. Recorded in the atmosphere, numerous sources of the infrared radiation seem to be a result of crystallization, condensation and deposition of water during fog and cloud formation. The effect under investigation must play a very important role in atmospheric phenomena: it is one of the sources of Earth's cooling; formation of hailstorm clouds is accompanied by intensive IRCR that could be detected for process characterization and meteorological warnings. IRCR seems to be used for atmospheric energy accumulation and together with the wind, falling water, solar and geothermal energies makes available the fifth source of ecologically pure energy.

  13. Estimating Sampling Biases and Measurement Uncertainties of AIRS-AMSU-A Temperature and Water Vapor Observations Using MERRA Reanalysis

    Science.gov (United States)

    Hearty, Thomas J.; Savtchenko, Andrey K.; Tian, Baijun; Fetzer, Eric; Yung, Yuk L.; Theobald, Michael; Vollmer, Bruce; Fishbein, Evan; Won, Young-In

    2014-01-01

    We use MERRA (Modern Era Retrospective-Analysis for Research Applications) temperature and water vapor data to estimate the sampling biases of climatologies derived from the AIRS/AMSU-A (Atmospheric Infrared Sounder/Advanced Microwave Sounding Unit-A) suite of instruments. We separate the total sampling bias into temporal and instrumental components. The temporal component is caused by the AIRS/AMSU-A orbit and swath that are not able to sample all of time and space. The instrumental component is caused by scenes that prevent successful retrievals. The temporal sampling biases are generally smaller than the instrumental sampling biases except in regions with large diurnal variations, such as the boundary layer, where the temporal sampling biases of temperature can be +/- 2 K and water vapor can be 10% wet. The instrumental sampling biases are the main contributor to the total sampling biases and are mainly caused by clouds. They are up to 2 K cold and greater than 30% dry over mid-latitude storm tracks and tropical deep convective cloudy regions and up to 20% wet over stratus regions. However, other factors such as surface emissivity and temperature can also influence the instrumental sampling bias over deserts where the biases can be up to 1 K cold and 10% wet. Some instrumental sampling biases can vary seasonally and/or diurnally. We also estimate the combined measurement uncertainties of temperature and water vapor from AIRS/AMSU-A and MERRA by comparing similarly sampled climatologies from both data sets. The measurement differences are often larger than the sampling biases and have longitudinal variations.

  14. Profiling water vapor mixing ratios in Finland by means of a Raman lidar, a satellite and a model

    Directory of Open Access Journals (Sweden)

    M. Filioglou

    2017-11-01

    Full Text Available We present tropospheric water vapor profiles measured with a Raman lidar during three field campaigns held in Finland. Co-located radio soundings are available throughout the period for the calibration of the lidar signals. We investigate the possibility of calibrating the lidar water vapor profiles in the absence of co-existing on-site soundings using water vapor profiles from the combined Advanced InfraRed Sounder (AIRS and the Advanced Microwave Sounding Unit (AMSU satellite product; the Aire Limitée Adaptation dynamique Développement INternational and High Resolution Limited Area Model (ALADIN/HIRLAM numerical weather prediction (NWP system, and the nearest radio sounding station located 100 km away from the lidar site (only for the permanent location of the lidar. The uncertainties of the calibration factor derived from the soundings, the satellite and the model data are  < 2.8, 7.4 and 3.9 %, respectively. We also include water vapor mixing ratio intercomparisons between the radio soundings and the various instruments/model for the period of the campaigns. A good agreement is observed for all comparisons with relative errors that do not exceed 50 % up to 8 km altitude in most cases. A 4-year seasonal analysis of vertical water vapor is also presented for the Kuopio site in Finland. During winter months, the air in Kuopio is dry (1.15±0.40 g kg−1; during summer it is wet (5.54±1.02 g kg−1; and at other times, the air is in an intermediate state. These are averaged values over the lowest 2 km in the atmosphere. Above that height a quick decrease in water vapor mixing ratios is observed, except during summer months where favorable atmospheric conditions enable higher mixing ratio values at higher altitudes. Lastly, the seasonal change in disagreement between the lidar and the model has been studied. The analysis showed that, on average, the model underestimates water vapor mixing ratios at high altitudes

  15. Precipitation recycling in West Africa - regional modeling, evaporation tagging and atmospheric water budget analysis

    Science.gov (United States)

    Arnault, Joel; Kunstmann, Harald; Knoche, Hans-Richard

    2015-04-01

    Many numerical studies have shown that the West African monsoon is highly sensitive to the state of the land surface. It is however questionable to which extend a local change of land surface properties would affect the local climate, especially with respect to precipitation. This issue is traditionally addressed with the concept of precipitation recycling, defined as the contribution of local surface evaporation to local precipitation. For this study the West African monsoon has been simulated with the Weather Research and Forecasting (WRF) model using explicit convection, for the domain (1°S-21°N, 18°W-14°E) at a spatial resolution of 10 km, for the period January-October 2013, and using ERA-Interim reanalyses as driving data. This WRF configuration has been selected for its ability to simulate monthly precipitation amounts and daily histograms close to TRMM (Tropical Rainfall Measuring Mission) data. In order to investigate precipitation recycling in this WRF simulation, surface evaporation tagging has been implemented in the WRF source code as well as the budget of total and tagged atmospheric water. Surface evaporation tagging consists in duplicating all water species and the respective prognostic equations in the source code. Then, tagged water species are set to zero at the lateral boundaries of the simulated domain (no inflow of tagged water vapor), and tagged surface evaporation is considered only in a specified region. All the source terms of the prognostic equations of total and tagged water species are finally saved in the outputs for the budget analysis. This allows quantifying the respective contribution of total and tagged atmospheric water to atmospheric precipitation processes. The WRF simulation with surface evaporation tagging and budgets has been conducted two times, first with a 100 km2 tagged region (11-12°N, 1-2°W), and second with a 1000 km2 tagged region (7-16°N, 6°W -3°E). In this presentation we will investigate hydro-atmospheric

  16. Effects of the gaseous and liquid water content of the atmosphere on range delay and Doppler frequency

    Science.gov (United States)

    Flock, W. L.

    1981-01-01

    When high precision is required for range measurement on Earth space paths, it is necessary to correct as accurately as possible for excess range delays due to the dry air, water vapor, and liquid water content of the atmosphere. Calculations based on representative values of atmospheric parameters are useful for illustrating the order of magnitude of the expected delays. Range delay, time delay, and phase delay are simply and directly related. Doppler frequency variations or noise are proportional to the time rate of change of excess range delay. Tropospheric effects were examined as part of an overall consideration of the capability of precision two way ranging and Doppler systems.

  17. Cavity-ring-down spectroscopy on water vapor in the range 555-604 nm

    NARCIS (Netherlands)

    Naus, H.; Ubachs, W.M.G.; Levelt, P.F.; Polyansky, O.L.; Zobov, N.F.; Tennyson, J.

    2001-01-01

    The method of pulsed cavity-ring-down spectroscopy was employed to record the water vapor absorption spectrum in the wavelength range 555-604 nm. The spectrum consists of 1830 lines, calibrated against the iodine standard with an accuracy of 0.01 cm

  18. Transport of water vapor and inert gas mixtures through highly selective and highly permeable polymer membranes

    NARCIS (Netherlands)

    Metz, S.J.; van de Ven, W.J.C.; Potreck, Jens; Mulder, M.H.V.; Wessling, Matthias

    2005-01-01

    This paper studies in detail the measurement of the permeation properties of highly permeable and highly selective polymers for water vapor/nitrogen gas mixtures. The analysis of the mass transport of a highly permeable polymer is complicated by the presence of stagnant boundary layers at feed and

  19. Water vapor selective thin film nanocomposite membranes prepared by functionalized Silicon nanoparticles

    NARCIS (Netherlands)

    Baig, Muhammad Irshad; Ingole, Pravin G.; Jeon, Jae deok; Hong, Seong Uk; Choi, Won Kil; Jang, Boyun; Lee, Hyung Keun

    2017-01-01

    In this work, we have reported a facile method to improve the water vapor permeation performance of thin film nanocomposite membranes by tailoring the surface properties of Silicon nanoparticles. Inductively coupled plasma technique was utilized to synthesize amorphous Silicon nanoparticles (~. 10.

  20. Analysis of combined heat and mass transfer of water-vapor in a ...

    African Journals Online (AJOL)

    Jn this paper, the combined heat and mass transfer of water-vapor into a cylindrical zeolite adsorber has been numerically simulated The twodimensional heat and mass transfer equations are numerically solved using gPROMS program - a general Process Modeling System [J] program, inserting the proper initial and ...

  1. Analysis of combined heat and mass transfer of water- Vapor in a ...

    African Journals Online (AJOL)

    In this paper, the combined heat and mass transfer of water-vapor into a cylindrical zeolite adsorber has been numerically simulated The twodimensional heat and mass transfer equations are numerically solved using gPROMS program - a general Process Modeling System {lJ program, inserting the proper initial and ...

  2. Interpretation of TOVS Water Vapor Radiances Using a Random Strong Line Model

    CERN Document Server

    Soden, B J; Soden, Brian J.; Bretherton, Francis P.

    1995-01-01

    This study illustrates the application of a random strong line (RSL) model of radiative transfer to the interpretation of satellite observations of the upwelling radiation in the 6.3 micron water vapor absorption band. The model, based upon an assemblage of randomly overlapped, strongly absorbing, pressure broadened lines, is compared to detailed radiative transfer calculations of the upper (6.7 micron) tropospheric water vapor radiance and demonstrated to be accurate to within ~ 1.2 K. Similar levels of accuracy are found when the model is compared to detailed calculations of the middle (7.3 micron) and lower (8.3 micron) tropospheric water vapor radiance, provided that the emission from the underlying surface is taken into account. Based upon these results, the RSL model is used to interpret TOVS-observed water vapor radiances in terms of the relative humidity averaged over deep layers of the upper, middle, and lower troposphere. We then present near-global maps of the geographic distribution and climatolog...

  3. Relating tropical ocean clouds to moist processes using water vapor isotope measurements

    Directory of Open Access Journals (Sweden)

    J. Lee

    2011-01-01

    Full Text Available We examine the co-variations of tropospheric water vapor, its isotopic composition and cloud types and relate these distributions to tropospheric mixing and distillation models using satellite observations from the Aura Tropospheric Emission Spectrometer (TES over the summertime tropical ocean. Interpretation of these process distributions must take into account the sensitivity of the TES isotope and water vapor measurements to variations in cloud, water, and temperature amount. Consequently, comparisons are made between cloud-types based on the International Satellite Cloud Climatology Project (ISSCP classification; these are clear sky, non-precipitating (e.g., cumulus, boundary layer (e.g., stratocumulus, and precipitating clouds (e.g. regions of deep convection. In general, we find that the free tropospheric vapor over tropical oceans does not strictly follow a Rayleigh model in which air parcels become dry and isotopically depleted through condensation. Instead, mixing processes related to convection as well as subsidence, and re-evaporation of rainfall associated with organized deep convection all play significant roles in controlling the water vapor distribution. The relative role of these moisture processes are examined for different tropical oceanic regions.

  4. Structure and Dynamical Influence of Water Vapor in the Lower Tropical Troposphere

    Science.gov (United States)

    Stevens, Bjorn; Brogniez, Hélène; Kiemle, Christoph; Lacour, Jean-Lionel; Crevoisier, Cyril; Kiliani, Johannes

    2017-11-01

    In situ, airborne and satellite measurements are used to characterize the structure of water vapor in the lower tropical troposphere—below the height, z_*, of the triple-point isotherm, T_*. The measurements are evaluated in light of understanding of how lower-tropospheric water vapor influences clouds, convection and circulation, through both radiative and thermodynamic effects. Lower-tropospheric water vapor, which concentrates in the first few kilometers above the boundary layer, controls the radiative cooling profile of the boundary layer and lower troposphere. Elevated moist layers originating from a preferred level of convective detrainment induce a profile of radiative cooling that drives circulations which reinforce such features. A theory for this preferred level of cumulus termination is advanced, whereby the difference between T_* and the temperature at which primary ice forms gives a `first-mover advantage' to glaciating cumulus convection, thereby concentrating the regions of the deepest convection and leading to more clouds and moisture near the triple point. A preferred level of convective detrainment near T_* implies relative humidity reversals below z* which are difficult to identify using retrievals from satellite-borne microwave and infrared sounders. Isotopologues retrievals provide a hint of such features and their ability to constrain the structure of the vertical humidity profile merits further study. Nonetheless, it will likely remain challenging to resolve dynamically important aspects of the vertical structure of water vapor from space using only passive sensors.

  5. Real-Time Water Vapor Maps from a GPS Surface Network: Construction, Validation, and Applications

    NARCIS (Netherlands)

    Haan, de S.; Holleman, I.; Holtslag, A.A.M.

    2009-01-01

    In this paper the construction of real-time integrated water vapor (IWV) maps from a surface network of global positioning system (GPS) receivers is presented. The IWV maps are constructed using a twodimensional variational technique with a persistence background that is 15 min old. The background

  6. Water vapor barrier and sorption properties of edible films from pullulan and rice wax.

    Science.gov (United States)

    Edible films were prepared by using various ratios of pullulan and rice wax. Freestanding composite films were obtained with up to 46.4% rice wax. Water vapor barrier properties of the film were improved with increased addition of rice wax. Moisture sorption isotherms were also studied to examine...

  7. The relationship between tropospheric wave forcing and tropical lower stratospheric water vapor

    Directory of Open Access Journals (Sweden)

    S. Dhomse

    2008-02-01

    Full Text Available Using water vapor data from HALOE and SAGE II, an anti-correlation between planetary wave driving (here expressed by the mid-latitude eddy heat flux at 50 hPa added from both hemispheres and tropical lower stratospheric (TLS water vapor has been obtained. This appears to be a manifestation of the inter-annual variability of the Brewer-Dobson (BD circulation strength (the driving of which is generally measured in terms of the mid-latitude eddy heat flux, and hence amount of water vapor entering the stratosphere. Some years such as 1991 and 1997 show, however, a clear departure from the anti-correlation which suggests that the water vapor changes in TLS can not be attributed solely to changes in extratropical planetary wave activity (and its effect on the BD circulation. After 2000 a sudden decrease in lower stratospheric water vapor has been reported in earlier studies based upon satellite data from HALOE, SAGE II and POAM III indicating that the lower stratosphere has become drier since then. This is consistent with a sudden rise in the combined mid-latitude eddy heat flux with nearly equal contribution from both hemispheres as shown here and with the increase in tropical upwelling and decrease in cold point temperatures found by Randel et al. (2006. The low water vapor and enhanced planetary wave activity (in turn strength of the BD circulation has persisted until the end of the satellite data records. From a multi-variate regression analysis applied to 27 years of NCEP and HadAT2 (radiosonde temperatures (up to 2005 with contributions from solar cycle, stratospheric aerosols and QBO removed, the enhancement wave driving after 2000 is estimated to contribute up to 0.7 K cooling to the overall TLS temperature change during the period 2001–2005 when compared to the period 1996–2000. NCEP cold point temperature show an average decrease of nearly 0.4 K from changes in the wave driving, which is consistent with observed mean TLS water vapor

  8. Secondary Organic Aerosol Formation by Reactive Condensation of Glyoxal and Water Vapor

    Science.gov (United States)

    Hastings, W. P.; Koehler, C. A.; de Haan, D. O.

    2004-05-01

    The formation of secondary organic aerosol particles by particle-phase reactions is currently of great interest. Glyoxal has been identified as a significant component in the particle phase in recent smog chamber aromatic oxidation studies. This is surprising because glyoxal has a high vapor pressure and phase partitioning theory would predict that it remain almost entirely in the gas phase. Growth of inorganic seed aerosol in a particle chamber was monitored by scanning mobility particle sizing during addition of gas-phase glyoxal and small amounts of water vapor. Glyoxal was observed to condense on inorganic seed aerosol at concentrations that are at least 100 times below its vapor pressure. This behavior can be explained by a chemical reaction: glyoxal is known to polymerize when exposed to water vapor. This polymerization may be a general mechanism for secondary aerosol formation by alpha-dicarbonyl compounds. The reactivity of hydrated and polymerized forms of glyoxal during analysis by gas chromatography was assessed. Hydrated glyoxal was found to convert to glyoxal at even slightly elevated temperatures in GC injection ports. We then showed that breakdown of solid-phase glyoxal trimer dihydrate, forming gas phase glyoxal and water vapor, occurs at temperatures just above 50 *C, the boiling point of glyoxal. These observations suggest that reports of particle-phase glyoxal are likely caused by GC sampling artifacts, and that the actual particulate species are instead polymerized forms of glyoxal. It does not appear that chemical derivatization protects glyoxal polymers from thermal breakdown during GC analysis. The existence in the particle phase of glyoxal polymers with negligable vapor pressures, rather than volatile glyoxal, is consistent with phase partitioning theory.

  9. Thermodynamics of droplet formation around a soluble condensation nucleus in the atmosphere of a solvent vapor.

    Science.gov (United States)

    Shchekin, A K; Shabaev, I V; Rusanov, A I

    2008-12-07

    An expression for the work of formation of a spherical droplet condensing on a soluble condensation nucleus out of a solvent vapor is derived. The dependence of the formation work on the solvent vapor chemical potential and the droplet and the nucleus residue sizes is analyzed. The balance of the solute matter between the liquid film and the nucleus residue and the effect of overlapping the surface layers of the thin film have been taken into account. It is shown that the equations of the chemical equilibrium of a solute and a solvent in the droplet, resulting from the generating properties of the formation work, coincide with the generalized Gibbs-Kelvin-Kohler and Ostwald-Freundlich equations. The numerical solution of these equations at a fixed number of molecules of the nucleus matter (at an initial size of the nucleus specified) has been performed in the case of the solvent vapor undersaturated over the bulk liquid solvent phase. The solution links the equilibrium sizes of the droplet and the soluble nucleus residue with the chemical potential or the pressure of the solvent vapor saturated over the droplet. It also determines the limiting sizes of the droplet with small nucleus residue above which the chemical equilibrium of the residue surface and the solution film does not exist. The existence of the limiting sizes is responsible for the specific behavior of the droplet thermodynamic characteristics and the work of droplet formation at deliquescence transition from the droplet state with a partly dissolved nucleus to the state of complete dissolution of the nucleus.

  10. GRIP LIDAR ATMOSPHERIC SENSING EXPERIMENT (LASE) V1

    Data.gov (United States)

    National Aeronautics and Space Administration — NASA's Lidar Atmospheric Sensing Experiment (LASE) system is an airborne DIAL (Differential Absorption Lidar) system used to measure water vapor, aerosols, and...

  11. Role of Water Vapor Content in the Effects of Aerosol on the Electrification of Thunderstorms: A Numerical Study

    Directory of Open Access Journals (Sweden)

    Pengguo Zhao

    2016-10-01

    Full Text Available We explored the role of the water vapor content below the freezing level in the response of idealized supercell storm electrical processes to increased concentrations of cloud condensation nuclei (CCN. Using the Weather Research and Forecasting model coupled with parameterizations electrification and discharging, we performed 30 simulations by varying both the CCN concentration and water vapor content below the freezing level. The sensitivity simulations showed a distinct response to increased concentrations of CCN, depending on the water vapor content below the freezing level. Enhancing CCN concentrations increased electrification processes of thunderstorms and produced a new negative charge region above the main positive charge center when there were ample amounts of water vapor below the freezing level. Conversely, there were weak effects on electrification and the charge structure in numerical experiments initialized with lower water vapor content below the freezing level.

  12. Fuel Evaporation in an Atmospheric Premixed Burner: Sensitivity Analysis and Spray Vaporization

    Directory of Open Access Journals (Sweden)

    Dávid Csemány

    2017-12-01

    Full Text Available Calculation of evaporation requires accurate thermophysical properties of the liquid. Such data are well-known for conventional fossil fuels. In contrast, e.g., thermal conductivity or dynamic viscosity of the fuel vapor are rarely available for modern liquid fuels. To overcome this problem, molecular models can be used. Currently, the measurement-based properties of n-heptane and diesel oil are compared with estimated values, using the state-of-the-art molecular models to derive the temperature-dependent material properties. Then their effect on droplet evaporation was evaluated. The critical parameters were liquid density, latent heat of vaporization, boiling temperature, and vapor thermal conductivity where the estimation affected the evaporation time notably. Besides a general sensitivity analysis, evaporation modeling in a practical burner ended up with similar results. By calculating droplet motion, the evaporation number, the evaporation-to-residence time ratio can be derived. An empirical cumulative distribution function is used for the spray of the analyzed burner to evaluate evaporation in the mixing tube. Evaporation number did not exceed 0.4, meaning a full evaporation prior to reaching the burner lip in all cases. As droplet inertia depends upon its size, the residence time has a minimum value due to the phenomenon of overshooting.

  13. Contribution of different processes to changes in tropical lower-stratospheric water vapor in chemistry–climate models

    Directory of Open Access Journals (Sweden)

    K. M. Smalley

    2017-07-01

    Full Text Available Variations in tropical lower-stratospheric humidity influence both the chemistry and climate of the atmosphere. We analyze tropical lower-stratospheric water vapor in 21st century simulations from 12 state-of-the-art chemistry–climate models (CCMs, using a linear regression model to determine the factors driving the trends and variability. Within CCMs, warming of the troposphere primarily drives the long-term trend in stratospheric humidity. This is partially offset in most CCMs by an increase in the strength of the Brewer–Dobson circulation, which tends to cool the tropical tropopause layer (TTL. We also apply the regression model to individual decades from the 21st century CCM runs and compare them to a regression of a decade of observations. Many of the CCMs, but not all, compare well with these observations, lending credibility to their predictions. One notable deficiency is that most CCMs underestimate the impact of the quasi-biennial oscillation on lower-stratospheric water vapor. Our analysis provides a new and potentially superior way to evaluate model trends in lower-stratospheric humidity.

  14. Reaction of HO2 with O3 and the effect of water vapor on HO2 kinetics

    Science.gov (United States)

    Demore, W. B.

    1979-01-01

    The effects of temperature and water vapor concentration on the ratio of the rate constant of the reaction HO2 + O3 yields OH + 2(O2) to the square root of the rate constant for the reaction HO2 + HO2 yields H2O2 + O2 are determined. Photolysis of H2-O2-O3 mixtures at 253.7 nm was carried out with H2O pressures in the range 0 to 15 torr at a temperature range of -42.5 to 61 C along with 184.9 nm photolysis of H2O-O2-O3 mixtures. It is shown that the rate of O3 photolysis is suppressed by the addition of water vapor and it is suggested that this effect is realized in the HO2 + HO2 yields H2O2 + O2 reaction. The calculated expression for the temperature dependence of the rate constant ratio is found to be in good agreement with that calculated from separate rate constants. Rate constants determined for the reaction OH + HO2 yields H2O + O2 are found to be higher than those previously determined, presumably due to increased pressure, indicating that atmospheric models should take into account the possible pressure dependences of the reactions considered.

  15. Simultaneous water vapor and dry air optical path length measurements and compensation with the large binocular telescope interferometer

    Science.gov (United States)

    Defrère, D.; Hinz, P.; Downey, E.; Böhm, M.; Danchi, W. C.; Durney, O.; Ertel, S.; Hill, J. M.; Hoffmann, W. F.; Mennesson, B.; Millan-Gabet, R.; Montoya, M.; Pott, J.-U.; Skemer, A.; Spalding, E.; Stone, J.; Vaz, A.

    2016-08-01

    The Large Binocular Telescope Interferometer uses a near-infrared camera to measure the optical path length variations between the two AO-corrected apertures and provide high-angular resolution observations for all its science channels (1.5-13 microns). There is however a wavelength dependent component to the atmospheric turbulence, which can introduce optical path length errors when observing at a wavelength different from that of the fringe sensing camera. Water vapor in particular is highly dispersive and its effect must be taken into account for high-precision infrared interferometric observations as described previously for VLTI/MIDI or the Keck Interferometer Nuller. In this paper, we describe the new sensing approach that has been developed at the LBT to measure and monitor the optical path length fluctuations due to dry air and water vapor separately. After reviewing the current performance of the system for dry air seeing compensation, we present simultaneous H-, K-, and N-band observations that illustrate the feasibility of our feedforward approach to stabilize the path length fluctuations seen by the LBTI nuller.

  16. Contribution of different processes to changes in tropical lower-stratospheric water vapor in chemistry-climate models

    Science.gov (United States)

    Smalley, Kevin M.; Dessler, Andrew E.; Bekki, Slimane; Deushi, Makoto; Marchand, Marion; Morgenstern, Olaf; Plummer, David A.; Shibata, Kiyotaka; Yamashita, Yousuke; Zeng, Guang

    2017-07-01

    Variations in tropical lower-stratospheric humidity influence both the chemistry and climate of the atmosphere. We analyze tropical lower-stratospheric water vapor in 21st century simulations from 12 state-of-the-art chemistry-climate models (CCMs), using a linear regression model to determine the factors driving the trends and variability. Within CCMs, warming of the troposphere primarily drives the long-term trend in stratospheric humidity. This is partially offset in most CCMs by an increase in the strength of the Brewer-Dobson circulation, which tends to cool the tropical tropopause layer (TTL). We also apply the regression model to individual decades from the 21st century CCM runs and compare them to a regression of a decade of observations. Many of the CCMs, but not all, compare well with these observations, lending credibility to their predictions. One notable deficiency is that most CCMs underestimate the impact of the quasi-biennial oscillation on lower-stratospheric water vapor. Our analysis provides a new and potentially superior way to evaluate model trends in lower-stratospheric humidity.

  17. Validation of MODIS integrated water vapor product against reference GPS data at the Iberian Peninsula

    Science.gov (United States)

    Vaquero-Martínez, Javier; Antón, Manuel; Ortiz de Galisteo, José Pablo; Cachorro, Victoria E.; Costa, Maria João; Román, Roberto; Bennouna, Yasmine S.

    2017-12-01

    In this work, the water vapor product from MODIS (MODerate-resolution Imaging Spectroradiometer) instrument, on-board Aqua and Terra satellites, is compared against GPS water vapor data from 21 stations in the Iberian Peninsula as reference. GPS water vapor data is obtained from ground-based receiver stations which measure the delay caused by water vapor in the GPS microwave signals. The study period extends from 2007 until 2012. Regression analysis in every GPS station show that MODIS overestimates low integrated water vapor (IWV) data and tends to underestimate high IWV data. R2 shows a fair agreement, between 0.38 and 0.71. Inter-quartile range (IQR) in every station is around 30-45%. The dependence on several parameters was also analyzed. IWV dependence showed that low IWV are highly overestimated by MODIS, with high IQR (low precision), sharply decreasing as IWV increases. Regarding dependence on solar zenith angle (SZA), performance of MODIS IWV data decreases between 50° and 90°, while night-time MODIS data (infrared) are quite stable. The seasonal cycles of IWV and SZA cause a seasonal dependence on MODIS performance. In summer and winter, MODIS IWV tends to overestimate the reference IWV value, while in spring and autumn the tendency is to underestimate. Low IWV from coastal stations is highly overestimated (∼60%) and quite imprecise (IQR around 60%). On the contrary, high IWV data show very little dependence along seasons. Cloud-fraction (CF) dependence was also studied, showing that clouds display a negligible impact on IWV over/underestimation. However, IQR increases with CF, except in night-time satellite values, which are quite stable.

  18. Correlation among Cirrus Ice Content, Water Vapor and Temperature in the TTL as Observed by CALIPSO and Aura-MLS

    Science.gov (United States)

    Flury, T.; Wu, D. L.; Read, W. G.

    2012-01-01

    Water vapor in the tropical tropopause layer (TTL) has a local radiative cooling effect. As a source for ice in cirrus clouds, however, it can also indirectly produce infrared heating. Using NASA A-Train satellite measurements of CALIPSO and Aura/MLS we calculated the correlation of water vapor, ice water content and temperature in the TTL. We find that temperature strongly controls water vapor (correlation r =0.94) and cirrus clouds at 100 hPa (r = -0.91). Moreover we observe that the cirrus seasonal cycle is highly (r =-0.9) anticorrelated with the water vapor variation in the TTL, showing higher cloud occurrence during December-January-February. We further investigate the anticorrelation on a regional scale and find that the strong anticorrelation occurs generally in the ITCZ (Intertropical Convergence Zone). The seasonal cycle of the cirrus ice water content is also highly anticorrelated to water vapor (r = -0.91) and our results support the hypothesis that the total water at 100 hPa is roughly constant. Temperature acts as a main regulator for balancing the partition between water vapor and cirrus clouds. Thus, to a large extent, the depleting water vapor in the TTL during DJF is a manifestation of cirrus formation.

  19. Analysis of weather changes in the region of Surabaya in 2015 and 2016 using water vapor data from GPS and Terra MODIS satellite image

    Science.gov (United States)

    Cahyadi, M. N.; Audah, S.; Mutia, N.; Aliyan, S. A.

    2017-07-01

    Sea surface temperature conditions in the territorial waters of Indonesia can be used as one indicator of a lot or least the content of water vapor in the atmosphere. It is closely related to the process of cloud formation in the region of Indonesia. Surabaya is the capital of the Indonesia's second largest potential for the occurrence of global warming due to climate change around the region. Global warming has the consequence of occurrence of climate variability, with marked by changes in temperature, and rainfall, as well as runoff of water. Monitoring the space-based Global Positioning System (GPS) and remote sensing satellite data such as Terra MODIS can be used in the field of meteorology. That is to measured the level of water vapor globally, with the approach of the amount of precipitable water vapor (PWV) in the atmosphere layer. It can be seen humidity conditions and the potential occurrence of rainfall in an area. The PWV value obtained from GPS processing had range 25.13 mm - 32.87 mm; average value is 27.38 mm and standard deviation is 2.018 mm. Based on the diurnal variation of the PWV GPS indicates that the climatic conditions in the area of Surabaya in 2015 showed the dry season, this is because the average values of PWV pretty low that occurred in July-September. But in September 2015 the PWV value occurrence an increase in water vapor and can be estimated that in the next month will be approaching rainy season.

  20. Water vaporization promotes coseismic fluid pressurization and buffers temperature rise

    NARCIS (Netherlands)

    Chen, Jianye|info:eu-repo/dai/nl/370819071; Niemeijer, André|info:eu-repo/dai/nl/370832132; Yao, Lu; Ma, Shengli

    2017-01-01

    We investigated the frictional properties of carbonate-rich gouge layers at a slip rate of 1.3 m/s, under dry and water-saturated conditions, while monitoring temperature at different locations on one of the gouge-host rock interfaces. All experiments showed a peak frictional strength of 0.4–0.7,

  1. Influence of the nucleation layer annealing atmosphere on the resistivity of GaN grown by metalorganic chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Weike, E-mail: luowk688@163.com; Li, Liang; Li, Zhonghui; Dong, Xun; Peng, Daqing; Zhang, Dongguo; Xu, Xiaojun

    2015-06-05

    Graphical abstract: LT-PL spectra of GaN samples A, B and C with sheet resistance of 1.1 × 10{sup 4} Ω/sq, 5.5 × 10{sup 4} Ω/sq and 1.0 × 10{sup 8} Ω/sq, respectively. - Highlights: • HR-GaN was fabricated by optimizing the nucleation layer annealing (NL) atmosphere. • The morphology of NLs annealed in different atmosphere has been investigated. • The resistance of GaN increased with density of edge type threading dislocations. • The PL results indicate that the HR-GaN is achieved due to the compensation of acceptor states. - Abstract: High-resistance (HR) GaN with sheet resistance of 1.0 × 10{sup 8} Ω/sq was grown on sapphire substrates using metal organic chemical vapor deposition. Sheet resistance of the GaN film increases 4 orders of magnitude by changing the nucleation layer (NL) annealing atmosphere from H{sub 2} to N{sub 2}. It is observed that the morphology of the NLs strongly depends on the annealing atmosphere. The analysis results based on high-resolution X-ray diffraction (HR-XRD) and etch pit density (EPD) measurements demonstrate that the density of edge-type threading dislocations increases with the proportion of the N{sub 2} in the annealing atmosphere. Photoluminescence (PL) spectra is employed to analyze the optical properties of GaN films. The XRD and PL results indicate the primary compensating mechanism is due to acceptor levels introduced by the increase in edge-type threading dislocations density. It is concluded that the annealing atmosphere of the NL controls sizes and densities of the nucleation islands, which affect electrical properties of GaN epitaxial films through changing the ratio of edge to screw/mixed-type threading dislocations.

  2. Velocity profile of water vapor inside a cavity with two axial inlets and two outlets

    Science.gov (United States)

    Guadarrama-Cetina, José; Ruiz Chavarría, Gerardo

    2014-03-01

    To study the dynamics of Breath Figure phenomenon, a control of both the rate of flow and temperature of water vapor is required. The experimental setup widely used is a non hermetically closed chamber with cylindrical geometry and axial inlets and outlets. In this work we present measurements in a cylindrical chamber with diameter 10 cm and 1.5 cm height, keeping a constant temperature (10 °C). We are focused in the velocity field when a gradient of the temperatures is produced between the base plate and the vapor. With a flux of water vapor of 250 mil/min at room temperature (21 °C), the Reynolds number measured in one inlet is 755. Otherwise, the temperatures of water vapor varies from 21 to 40 °C. The velocity profile is obtained by hot wire anemometry. We identify the stagnations and the possibly instabilities regions for an empty plate and with a well defined shape obstacle as a fashion sample. Facultad de Ciencias, UNAM.

  3. Subseasonal variability of water vapor in the upper stratosphere/lower mesosphere over Northern Europe in winter 2009/2010

    Science.gov (United States)

    Peters, D. H. W.; Hallgren, K.; Lübken, F.-J.; Hartogh, P.

    2014-07-01

    For the upper stratosphere and lower mesosphere (USLM) we used microwave spectrometer measurements of water vapor to investigate the cause of subseasonal variability over Northern Europe: at ALOMAR (Andenes, 69.3° N, 16.1° E), Northern Norway, and at the Leibniz Institute of Atmospheric Physics (Kühlungsborn, 54.2° N, 11.8° E), Northern Germany, for winter 2009/2010. The MERRA data set of NASA is applied to study the dynamical link between the local variability of H2O and transport in the USLM. Besides a slow increase in January and a stronger decrease in February and March 2010, episodes of significant increase and decrease of H2O were found over Northern Germany. These structural changes are in good agreement with MERRA which show similar patterns induced by a dominant conservative horizontal transport of H2O. Due to the strong negative meridional gradient and mixing barrier, higher values of water vapor have been observed outside the polar vortex and lower values inside. We found that the complex polar vortex evolution over Northern Germany during the minor stratospheric sudden warming (mSSW) in the beginning of December 2009 and the major warming (MSSW) at the end of January 2010, as well as between the two, fits well into this relationship. An episode of strong increase in water vapor over ALOMAR at about 55-60 km altitude was observed during the MSSW on the 27th of January 2010 resulting in a significant double peak in altitude. Based on MERRA data we show that this dual peak was caused by a relatively strong regional northward propagation of more moist air in the lower mesosphere. In the lower mesosphere strong polar intrusion of warm and moist air occurred mainly over Northern Europe resulting in a well-mixed polar anticyclone on the 30th of January. In comparison with observations the local maxima of H2O in MERRA are underestimated by approximately 1-2 ppmv. After the MSSW, the vertical descent rate of the MERRA reanalysis is half as much as the

  4. Attenuation of concentration fluctuations of water vapor and other trace gases in turbulent tube flow

    DEFF Research Database (Denmark)

    Massman, W.J.; Ibrom, Andreas

    2008-01-01

    the turbulent tube flow issue for both passive and sorbing tracers with the intent of developing a physically-based semi-empirical model that describes the attenuation associated with water vapor fluctuations. Toward this end, we develop a new model of tube flow dynamics (radial profiles of the turbulent...... diffusivity and tube airstream velocity). We compare our new passive-tracer formulation with previous formulations in a systematic and unified way in order to assess how sensitive the passive-tracer results depend on fundamental modeling assumptions. We extend the passive tracer model to the vapor sorption....../desorption case by formulating the model's wall boundary condition in terms of a physically-based semi-empirical model of the sorption/desorption vapor fluxes. Finally we synthesize all modeling and observational results into a single analytical expression that captures the effects of the mean ambient humidity...

  5. Energy and water vapor transport across a simplified cloud-clear air interface

    CERN Document Server

    Gallana, Luca; De Santi, Francesca; Iovieno, Michele; Tordella, Daniela

    2015-01-01

    We consider a simplified physics of the could interface where condensation, evaporation and radiation are neglected and momentum, thermal energy and water vapor transport is represented in terms of the Boussinesq model coupled to a passive scalar transport equation for the vapor. The interface is modeled as a layer separating two isotropic turbulent regions with different kinetic energy and vapor concentration. In particular, we focus on the small scale part of the inertial range as well as on the dissipative range of scales which are important to the micro-physics of warm clouds. We have numerically investigated stably stratified interfaces by locally perturbing at an initial instant the standard temperature lapse rate at the cloud interface and then observing the temporal evolution of the system. When the buoyancy term becomes of the same order of the inertial one, we observe a spatial redistribution of the kinetic energy which produce a concomitant pit of kinetic energy within the mixing layer. In this sit...

  6. Sulfuric Acid Vapor in the Atmosphere of Venus as Observed by the Venus Express Radio Science Experiment VeRa

    Science.gov (United States)

    Oschlisniok, Janusz; Pätzold, Martin; Häusler, Bernd; Tellmann, Silvia; Bird, Michael; Andert, Thomas

    2017-10-01

    The cloud deck within Venus' atmosphere, which covers the entire planet between approx. 50 and 70 km altitude, consists mostly of liquid and gaseous sulfuric acid. The gaseous part increases strongly just below the main clouds and builds an approx. 15 km thick haze layer of H2SO4. This region is responsible for a strong absorption of radio waves as seen in Mariner, Pioneer Venus, Magellan and Venera radio science observations. The amount of H2SO4 is derived from the observed absorption as a function of altitude and latitude. The radio science experiment VeRa onboard Venus Express probed the atmosphere of Venus between 2006 and 2015 with radio signals at 13 cm (S-band) and 3.6 cm (X-band) wavelengths. The orbit of the Venus Express spacecraft allowed to sound the atmosphere over a wide range of latitudes and local times providing a global picture of the sulfuric acid vapor distribution. We present absorptivity and H2SO4 profiles derived from X-band signal attenuation for the time of the entire Venus Express mission. More than 600 H2SO4 profiles show the global sulfuric acid vapor distribution covering the northern and southern hemisphere on the day- and night side of the planet. A distinct latitudinal H2SO4 gradient and a southern northern symmetry are clearly visible. Observations over 8 years allow to study also long-term variations. Indications for temporal H2SO4 variations are found, at least at northern polar latitudes. The results shall be compared with observations retrieved by other experiments (VIRTIS, SPICAV) onboard Venus Express as well as with previous observations like Mariner, Pioneer Venus and the Magellan spacecraft.

  7. Water, heat, and vapor flow in a deep vadose zone under arid and hyper-arid conditions: a numerical study.

    Science.gov (United States)

    Madi, Raneem; de Rooij, Gerrit H.

    2017-04-01

    Groundwater recharge in arid regions is notoriously difficult to quantify. One reason is data scarcity: reliable weather records (rainfall, potential evapotranspiration rate, temperature) are typically lacking, the soil properties over the entire extent of the often very deep vadose zone are usually unknown, and the effect of sparse vegetation, wadis, (biological) soil crusts, and hard pans on infiltration and evaporation is difficult to quantify. Another reason is the difficulty of modeling the intricately coupled relevant processes over extended periods of time: coupled flow of liquid water, water vapor, and heat in a very deep soil in view of considerable uncertainty at the soil surface as indicated above, and over large spatial extents. In view of this myriad of problems, we limited ourselves to the simulation of 1-dimensional coupled flow of water, heat, and vapor in an unvegetated deep vadose zone. The conventional parameterizations of the soil hydraulic properties perform poorly under very dry conditions. We therefore selected an alternative that was developed specifically for dry circumstances and modified another to eliminate the physically implausible residual water content that rendered it of limited use for desert environments. The issue of data scarcity was resolved by using numerically generated rainfall records combined with a simple model for annual and daily temperature fluctuations. The soil was uniform, and the groundwater depth was constant at 100 m depth, which provided the lower boundary condition. The geothermal gradient determined the temperature at the groundwater level. We generated two scenarios with 120 years of weather in an arid and a hyper-arid climate. The initial condition was established by first starting with a somewhat arbitrary unit gradient initial condition corresponding to a small fraction of the annual average rainfall and let the model run through the 120-year atmospheric forcing. The resulting profile of matric potential

  8. Atmospheric humidity

    Science.gov (United States)

    Water vapor plays a critical role in earth's atmosphere. It helps to maintain a habitable surface temperature through absorption of outgoing longwave radiation, and it transfers trmendous amounts of energy from the tropics toward the poles by absorbing latent heat during evaporation and subsequently...

  9. Measurement of turbulent water vapor fluxes using a lightweight unmanned aerial vehicle system

    Directory of Open Access Journals (Sweden)

    R. M. Thomas

    2012-01-01

    Full Text Available We present here the first application of a lightweight unmanned aerial vehicle (UAV system designed to measure turbulent properties and vertical latent heat fluxes (λE. Such measurements are crucial to improve our understanding of linkages between surface moisture supply and boundary layer clouds and phenomena such as atmospheric rivers. The application of UAVs allows for measurements on spatial scales complimentary to satellite, aircraft, and tower derived fluxes. Key system components are: a turbulent gust probe; a fast response water vapor sensor; an inertial navigation system (INS coupled to global positioning system (GPS; and a 100 Hz data logging system. We present measurements made in the continental boundary layer at the National Aeronautics and Space Administration (NASA Dryden Research Flight Facility located in the Mojave Desert. Two flights consisting of several horizontal straight flux run legs up to ten kilometers in length and between 330 and 930 m above ground level (m a.g.l. are compared to measurement from a surface tower. Surface measured λE ranged from −53 W m−2 to 41 W m−2, and the application of a Butterworth High Pass Filter (HPF to the datasets improved agreement to within +/−12 W m−2 for 86% of flux runs, by removing improperly sampled low frequency flux contributions. This result, along with power and co-spectral comparisons and consideration of the differing spatial scales indicates the system is able to resolve vertical fluxes for the measurement conditions encountered. Challenges remain, and the outcome of these measurements will be used to inform future sampling strategies and further system development.

  10. Method for the production of hydrogen from water vapor

    Energy Technology Data Exchange (ETDEWEB)

    Seitzer, W.H.

    1975-05-07

    The invention concerns a one-stage method for thermal water dissociation and the removal of the oxygen from the resulting oxyhydrogen gas. According to the invention a) the wet oxyhydrogen gas is led past a wall made of hard-to-melt oxide, preferably zirconium oxide, which allows the penetration of oxygen, b) the oxygen diffusing through the wall is continuously removed by reaction with a reducing gas, and c) the thus produced reaction heat is used to heat the plant.

  11. Improving Atmospheric Correction for Visible/Short Wave Infrared (VSWIR) Imaging Spectrometers with Iterative Fitting of Absorption By Three Phases of Water

    Science.gov (United States)

    Pennington, E. A.; Thompson, D. R.; Green, R. O.; Gao, B. C.

    2014-12-01

    Airborne imaging spectrometers like the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) offer valuable insight into the Earth's terrestrial and ocean ecosystems, mineralogy, and land use. Estimating surface reflectance requires accounting for atmospheric absorption, which is sensitive to the local abundance of water vapor. Analysts typically estimate water vapor concentrations using the depths of absorption features, which can be inaccurate by up to 50% over surface features containing liquid water or ice. This can bias the retrieved water vapor maps and create atmospheric artifacts in reflectance spectra. A new retrieval method offers significant accuracy improvements over plant canopies or ice by estimating the path lengths of all three phases of water simultaneously, adjusting absorptions to best fit the measurement over a broader spectral interval. This paper assesses the remaining sources of error for the three-phase retrieval technique. We analyze retrievals for synthetic data when the 940 and 1140 nm wavelength features are fitted, for initial vapor path estimates ranging from 0 to ±50% accuracy. These tests indicate that most error comes from inaccuracy in the initial path estimate used to obtain vapor absorption coefficients. We evaluate a modified algorithm that uses multiple iterations to refine this estimate. Error is found to approach a constant value, demonstrating improved robustness to initialization conditions. We also assess the new iterative method using corrected AVIRIS data over various environments. The iterative method yields significantly better water vapor maps, reducing spurious correlations between vegetation canopy water and vapor estimates. The new iterative method offers accuracy improvements over traditional Visible/Short Wave Infrared (VSWIR) atmospheric correction methods, at modest computational cost.

  12. Spatial Correlations of Anomalies of Tropospheric Temperature and Water Vapor, Cloud Cover, and OLR with the El Nino Index

    Science.gov (United States)

    Susskind, Joel; Iredell, Lena; Lee, Jae N.

    2014-01-01

    In this presentation, we will show AIRS Version-6 area weighted anomaly time series over the time period September 2002 through August 2014 of atmospheric temperature and water vapor profiles as a function of height. These anomaly time series show very different behaviors in the stratosphere and in the troposphere. Tropical mean stratospheric temperature anomaly time series are very strongly influenced by the Quasi-Biennial Oscillation (QBO) with large anomalies that propagate downward from 1 mb to 100 mb with a period of about two years. AIRS stratospheric temperature anomalies are in good agreement with those obtained by MLS over a common period. Tropical mean tropospheric temperature profile anomalies appear to be totally disconnected from those of the stratosphere and closely follow El Nino La Nina activity.

  13. Evidence of non-LTE Effects in Mesospheric Water Vapor from Spectrally-Resolved Emissions Observed by CIRRIS-1A

    Science.gov (United States)

    Zhou, D. K.; Mlynczak, M. G.; Lopez-Puertas, M.; Zaragoza, G.

    1999-01-01

    Evidence of non-LTE effects in mesospheric water vapor as determined by infrared spectral emission measurements taken from the space shuttle is reported. A cryogenic Michelson interferometer in the CIRRIS-1A shuttle payload yielded high quality, atmospheric infrared spectra. These measurements demonstrate the enhanced daytime emissions of H2O (020-010) which are the result of non-LTE processes and in agreement with non-LTE models. The radiance ratios of H2O (010 to 000) and (020 to 010) Q(1) transitions during daytime are compared with non-LTE model calculations to assess the vibration-to-vibration exchange rate between H2O and O2 in the mesosphere. An exchange rate of 1.2 x 10(exp -12)cc/s is derived.

  14. Progress on development of an airborne two-micron IPDA lidar for water vapor and carbon dioxide column measurements

    Science.gov (United States)

    Singh, Upendra N.; Petros, Mulugeta; Refaat, Tamer F.; Yu, Jirong; Antill, Charles W.; Taylor, Bryant D.; Bowen, Stephen C.; Welters, Angela M.; Remus, Ruben G.; Wong, Teh-Hwa; Reithmaier, Karl; Lee, Jane; Ismail, Syed

    2017-09-01

    An airborne 2-μm triple-pulse integrated path differential absorption (IPDA) lidar is currently under development at NASA Langley Research Center (LaRC). This lidar targets both atmospheric carbon dioxide (CO2) and water vapor (H2O) column measurements, simultaneously. Advancements in the development of this IPDA lidar are presented in this paper. Updates on advanced two-micron triple-pulse high-energy laser transmitter will be given including packaging and lidar integration status. In addition, receiver development updates will also be presented. This includes a state-of-the-art detection system integrated at NASA Goddard Space Flight Center. This detection system is based on a newly developed HgCdTe (MCT) electron-initiated avalanche photodiode (e-APD) array. Future plan for IPDA lidar system for ground integration, testing and flight validation will be discussed.

  15. Water vapor weathering of Taurus-Littrow orange soil - A pore-structure analysis

    Science.gov (United States)

    Cadenhead, D. A.; Mikhail, R. S.

    1975-01-01

    A pore-volume analysis was performed on water vapor adsorption data previously obtained on a fresh sample of Taurus-Littrow orange soil, and the analysis was repeated on the same sample after its exposure to moist air for a period of approximately six months. The results indicate that exposure of an outgassed sample to high relative pressures of water vapor can result in the formation of substantial micropore structure, the precise amount being dependent on the sample pretreatment, particularly the outgassing temperature. Micropore formation is explained in terms of water penetration into surface defects. In contrast, long-term exposure to moist air at low relative pressures appears to reverse the process with the elimination of micropores and enlargement of mesopores possibly through surface diffusion of metastable adsorbent material. The results are considered with reference to the storage of lunar samples.

  16. Influence of dehydration temperature on water vapor adsorption, dissolution behavior and surface property of ampicillin.

    Science.gov (United States)

    Moribe, Kunikazu; Wongmekiat, Arpansiree; Hyakutake, Yuki; Tozuka, Yuichi; Oguchi, Toshio; Yamamoto, Keiji

    2005-01-20

    Several specimens of anhydrous ampicillin were prepared by heating the ampicillin trihydrate at 100, 120, 140 and 160 degrees C. The effects of dehydration temperature on water vapor adsorption, dissolution behavior and surface property were investigated. The water vapor adsorption of anhydrous ampicillin was studied at 89% relative humidity, 40 degrees C and the water vapor adsorption rate was found to decrease with increase of dehydration temperature. Dissolution profiles of the various anhydrous specimens were investigated in 96% ethanol at 35 degrees C by the static disk method. The anhydrous form prepared at higher dehydration temperature exhibited faster dissolution rate. Solid phase transformation from the anhydrous form to the trihydrate form occurred during the dissolution test. The rate of phase transformation during the dissolution test decreased with increasing dehydration temperature. Topographic difference of the anhydrous forms prepared at 100 and 160 degrees C was not observed by scanning electron microscopy (SEM) and atomic force microscopy (AFM); however, difference of the microstructural properties was apparently observed by the AFM phase image. Surface free energy study revealed that when ampicillin was dehydrated at high temperature, the sample surface became more hydrophobic resulting in less interaction force with water and slow water sorption rate. From the results, we concluded that the polarity of sample surface induced by dehydration of ampicillin would affect the phase transformation and dissolution behavior.

  17. Oxidation of uranium in low partial pressures of oxygen and water vapor at 100/sup 0/C

    Energy Technology Data Exchange (ETDEWEB)

    Weirick, L J

    1984-06-01

    Oxygen isotope studies indicate that a previously proposed theory describing the oxidation of uranium is incorrect. This theory had proposed that the uranium reacted directly with water vapor to form uranium dioxide and hydrogen and the hydrogen subsequently reacted with the free oxygen to form water. This study shows that oxygen reacts directly with uranium, the role of water vapor being to affect the uranium oxide structure which is formed. The reaction rate of uranium with water vapor in the absence of oxygen was linear and proportional to the water vapor pressure for water vapor pressures between 2 and 20 Torr. Hydrogen was produced by the reaction at a rate of almost two moles for every one mole of uranium dioxide formed. The oxide was identified as UO/sub 2/ /sub 0/. The reaction of uranium with water vapor in the presence of oxygen showed three separate regions of reaction response. In one region, at low oxygen pressure, the reaction was the same as with no oxygen, a second region at oxygen pressures between 0.05 and 1 Torr was a transition stage and in the third region, at oxygen pressures above 1 Torr, the reaction rate was linear and independent of both oxygen and water vapor pressure. The oxide formed was identified as nominally U/sub 4/O/sub 9/. Only a small amount of hydrogen was produced.

  18. Water liquid-vapor interface subjected to various electric fields: A molecular dynamics study

    Science.gov (United States)

    Nikzad, Mohammadreza; Azimian, Ahmad Reza; Rezaei, Majid; Nikzad, Safoora

    2017-11-01

    Investigation of the effects of E-fields on the liquid-vapor interface is essential for the study of floating water bridge and wetting phenomena. The present study employs the molecular dynamics method to investigate the effects of parallel and perpendicular E-fields on the water liquid-vapor interface. For this purpose, density distribution, number of hydrogen bonds, molecular orientation, and surface tension are examined to gain a better understanding of the interface structure. Results indicate enhancements in parallel E-field decrease the interface width and number of hydrogen bonds, while the opposite holds true in the case of perpendicular E-fields. Moreover, perpendicular fields disturb the water structure at the interface. Given that water molecules tend to be parallel to the interface plane, it is observed that perpendicular E-fields fail to realign water molecules in the field direction while the parallel ones easily do so. It is also shown that surface tension rises with increasing strength of parallel E-fields, while it reduces in the case of perpendicular E-fields. Enhancement of surface tension in the parallel field direction demonstrates how the floating water bridge forms between the beakers. Finally, it is found that application of external E-fields to the liquid-vapor interface does not lead to uniform changes in surface tension and that the liquid-vapor interfacial tension term in Young's equation should be calculated near the triple-line of the droplet. This is attributed to the multi-directional nature of the droplet surface, indicating that no constant value can be assigned to a droplet's surface tension in the presence of large electric fields.

  19. FLUXNET: A new tool to study the temporal and spatial variability of ecosystem-scale carbon dioxide, water vapor, and energy flux densities

    DEFF Research Database (Denmark)

    Baldocchi, D.; Falge, E.; Gu, L.

    2001-01-01

    , the project supports calibration and flux intercomparison activities. This activity ensures that data from the regional networks are intercomparable. And third, FLUXNET supports the synthesis, discussion, and communication of ideas and data by supporting project scientists, workshops, and visiting scientists...... of annual ecosystem carbon and water balances, to quantify the response of stand-scale carbon dioxide and water vapor flux densities to controlling biotic and abiotic factors, and to validate a hierarchy of soil-plant-atmosphere trace gas exchange models. Findings so far include 1) net CO2 exchange...

  20. A SEARCH FOR WATER IN THE ATMOSPHERE OF HAT-P-26b USING LDSS-3C

    Energy Technology Data Exchange (ETDEWEB)

    Stevenson, Kevin B.; Bean, Jacob L.; Seifahrt, Andreas; Gilbert, Gregory J. [Department of Astronomy and Astrophysics, University of Chicago, 5640 S Ellis Avenue, Chicago, IL 60637 (United States); Line, Michael R. [NASA Ames Research Center, Moffett Field, CA 94035 (United States); Désert, Jean-Michel [Anton Pannekoek Institute for Astronomy, University of Amsterdam, Amsterdam (Netherlands); Fortney, Jonathan J., E-mail: kbs@uchicago.edu [Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States)

    2016-02-01

    The characterization of a physically diverse set of transiting exoplanets is an important and necessary step toward establishing the physical properties linked to the production of obscuring clouds or hazes. It is those planets with identifiable spectroscopic features that can most effectively enhance our understanding of atmospheric chemistry and metallicity. The newly commissioned LDSS-3C instrument on Magellan provides enhanced sensitivity and suppressed fringing in the red optical, thus advancing the search for the spectroscopic signature of water in exoplanetary atmospheres from the ground. Using data acquired by LDSS-3C and the Spitzer Space Telescope, we search for evidence of water vapor in the transmission spectrum of the Neptune-mass planet HAT-P-26b. Our measured spectrum is best explained by the presence of water vapor, a lack of potassium, and either a high-metallicity, cloud-free atmosphere or a solar-metallicity atmosphere with a cloud deck at ∼10 mbar. The emergence of multi-scale-height spectral features in our data suggests that future observations at higher precision could break this degeneracy and reveal the planet’s atmospheric chemical abundances. We also update HAT-P-26b’s transit ephemeris, t{sub 0} = 2455304.65218(25) BJD{sub TDB}, and orbital period, p = 4.2345023(7) days.

  1. Ozone and Water Vapor Measurements by Raman Lidar in the Planetary Boundary Layer: Error Sources and Field Measurements

    Science.gov (United States)

    Lazzarotto, Benoit; Frioud, Max; Larcheveque, Gilles; Mitev, Valentin; Quaglia, Philippe; Simeonov, Valentin; Thompson, Anne; VandenBergh, Hubert; Calpini, Bertrand; Einaudi, Franco (Technical Monitor)

    2000-01-01

    Why do we need time series of ozone and water vapor profiles at low altitude? The degradation of air quality is a very serious environmental problem that affects urban and industrial areas worldwide. Air pollution injures human health and ecosystems, diminishes crop yield, and spoils patrimony and materials. The phenomena involved in air pollution are very complex. Once emitted into the atmosphere, (primary) pollutants are transported, dispersed, transformed by gas/solid phase change and chemical reaction, and finally removed by dry and wet deposition. Most challenging is the fact that the health and environmental impacts of secondary pollutants (formed in the atmosphere) are frequently more severe than those of their precursors (primary pollutants). This is the case of ozone and other photochemical pollutants, such as peroxyacetil nitrate (PAN) and secondary particles, produced in the atmosphere by the photo-oxidation volatile organic compounds (VOC) catalyzed by nitrogen oxides (NO(sub x)). Photochemical air pollution is a complex science because of the non-linearity of its response to changes in primary emission.

  2. In-Situ Water Vapor Probe for a Robot Arm-Mounted, Compact Water Vapor Analyzer: Preliminary Results

    Science.gov (United States)

    Socki, Richard A.; Niles, Paul B.; Cabiran, Mike; Rossi, Chris; Sun, Tao

    2013-01-01

    This work describes the ongoing development of an instrument package for the in-situ detection and isotopic analysis of water (from ice, icy soils, and hydrated minerals) on future lunar, asteroid, or martian exploration missions. This instrument is intended to be mounted on a robotic arm and be brought to the sample, rather than necessitating expensive and complicated sample handling to bring the sample to the instrument.

  3. Use of a novel new irrigation system to observe and model water vapor flow through dry soils

    Science.gov (United States)

    Todman, L. C.; Ireson, A. M.; Butler, A. P.; Templeton, M.

    2013-12-01

    In dry soils hydraulic connectivity within the liquid water phase decreases and vapor flow becomes a significant transport mechanism for water. The temperature or solute concentration of the liquid phase affects the vapor pressure of the surrounding air, thus temperature or solute gradients can drive vapor flows. However, in extremely dry soils where water is retained by adsorption rather than capillarity, vapor flows can also occur. In such soils tiny changes in water content significantly affect the equilibrium vapor pressure in the soil, and hence small differences in water content can initiate vapor pressure gradients. In many field conditions this effect may be negligible compared to vapor flows driven by other factors. However, flows of this type are particularly significant in a new type of subsurface irrigation system which uses pervaporation, via a polymer tubing, as the mechanism for water supply. In this system, water enters the soil in vapor phase. Experiments using this system therefore provide a rare opportunity to observe vapor flows initiating from a subsurface source without significant injection of heat. A model was developed to simulate water flow through the soil in liquid and vapor phase. In this model it was assumed that the two phases were in equilibrium. The equilibrium relationship was defined by a new mathematical expression that was developed to fit experimental data collected to characterize the sorption isotherm of three soils (sand, saline sand and top soil). The osmotic potential of the saline sand was defined as a function of water content using a continuous mathematical expression. The model was then calibrated to fit the data from laboratory experiments, in which the vapor flow into and out of the soil were quantified. The model successfully reproduced experimental observations of the total water flux, relative humidity and water content distribution in three soil types. This suggests that the model, including the proposed

  4. Asymptotic analysis of the contact-line microregion for a perfectly wetting volatile liquid in a pure-vapor atmosphere

    Science.gov (United States)

    Rednikov, A. Ye.; Colinet, P.

    2017-12-01

    We revisit the Wayner problem of the microregion of a contact line at rest formed by a perfectly wetting single-component liquid on an isothermal superheated flat substrate in an atmosphere of its own pure vapor. The focus is on the evaporation-induced apparent contact angles. The microregion is shaped by the effects of viscosity, Laplace and disjoining pressures (the latter in the form of an inverse-cubic law), and evaporation. The evaporation is in turn determined by heat conduction across the liquid film, kinetic resistance, and the Kelvin effect (i.e., saturation-condition dependence on the liquid-vapor pressure difference). While an asymptotic limit of large kinetic resistances was considered by Morris nearly two decades ago [J. Fluid Mech. 432, 1 (2001)], here we are concerned rather with matched asymptotic expansions in the limits of weak and strong Kelvin effects. Certain extensions are also touched upon within the asymptotic analysis. These are a more general form of the disjoining pressure and account for the Navier slip. Most notably, these also include the possibility of Wayner's extended microfilms (covering macroscopically dry parts of the substrate) actually getting truncated. A number of isolated cases encountered in the literature are thereby systematically recovered.

  5. Synthesis of Hydrophobic Mesoporous Material MFS and Its Adsorption Properties of Water Vapor

    Directory of Open Access Journals (Sweden)

    Guotao Zhao

    2014-01-01

    Full Text Available Fluorine-containing hydrophobic mesoporous material (MFS with high surface area is successfully synthesized with hydrothermal synthesis method by using a perfluorinated surfactant SURFLON S-386 template. The adsorption properties of water vapor on the synthesized MFS are also investigated by using gravimetric method. Results show that SEM image of the MFS depicted roundish morphology with the average crystal size of 1-2 μm. The BET surface area and total pore volume of the MFS are 865.4 m2 g−1 and 0.74 cm3 g−1 with a narrow pore size distribution at 4.9 nm. The amount of water vapor on the MFS is about 0.41 mmol g−1 at 303 K, which is only 52.6% and 55.4% of MCM-41 and SBA-15 under the similar conditions, separately. The isosteric adsorption heat of water on the MFS is gradually about 27.0–19.8 kJ mol−1, which decreases as the absorbed water vapor amount increases. The value is much smaller than that on MCM-41 and SBA-15. Therefore, the MFS shows more hydrophobic surface properties than the MCM-41 and SBA-15. It may be a kind of good candidate for adsorption of large molecule and catalyst carrier with high moisture resistance.

  6. Water vapor motion signal extraction from FY-2E longwave infrared window images for cloud-free regions: The temporal difference technique

    Science.gov (United States)

    Yang, Lu; Wang, Zhenhui; Chu, Yanli; Zhao, Hang; Tang, Min

    2014-11-01

    The aim of this study is to calculate the low-level atmospheric motion vectors (AMVs) in clear areas with FY-2E IR2 window (11.59-12.79 μm) channel imagery, where the traditional cloud motion wind technique fails. A new tracer selection procedure, which we call the temporal difference technique, is demonstrated in this paper. This technique makes it possible to infer low-level wind by tracking features in the moisture pattern that appear as brightness temperature ( T B) differences between consecutive sequences of 30-min-interval FY-2E IR2 images over cloud-free regions. The T B difference corresponding to a 10% change in water vapor density is computed with the Moderate Resolution Atmospheric Transmission (MODTRAN4) radiative transfer model. The total contribution from each of the 10 layers is analyzed under four typical atmospheric conditions: tropical, midlatitude summer, U.S. standard, and midlatitude winter. The peak level of the water vapor weighting function for the four typical atmospheres is assigned as a specific height to the T B "wind". This technique is valid over cloud-free ocean areas. The proposed algorithm exhibits encouraging statistical results in terms of vector difference (VD), speed bias (BIAS), mean vector difference (MVD), standard deviation (SD), and root-mean-square error (RMSE), when compared with the wind field of NCEP reanalysis data and rawinsonde observations.

  7. Calculation of Liquid Water-Hydrate-Methane Vapor Phase Equilibria from Molecular Simulations

    DEFF Research Database (Denmark)

    Jensen, Lars; Thomsen, Kaj; von Solms, Nicolas

    2010-01-01

    Monte Carlo simulation methods for determining fluid- and crystal-phase chemical potentials are used for the first time to calculate liquid water-methane hydrate-methane vapor phase equilibria from knowledge of atomistic interaction potentials alone. The water and methane molecules are modeled...... potential of the zero-occupancy hydrate system using thermodynamic integration from an Einstein crystal reference state, and (iii) thermodynamic integration to obtain the water and guest molecules' chemical potentials as a function of the hydrate occupancy. The three-phase equilibrium curve is calculated...... value at corresponding conditions. While computationally intensive, simulations such as these are essential to map the thermodynamically stable conditions for hydrate systems....

  8. Adsorptive water removal from dichloromethane and vapor-phase regeneration of a molecular sieve 3A packed bed

    OpenAIRE

    Jovic, S Slavisa; Laxminarayan, Y; Keurentjes, JTF Jos; Schouten, JC Jaap; Schaaf, van der, S.

    2017-01-01

    The drying of dichloromethane with a molecular sieve 3A packed bed process is modeled and experimentally verified. In the process, the dichloromethane is dried in the liquid phase and the adsorbent is regenerated by water desorption with dried dichloromethane product in the vapor phase. Adsorption equilibrium experiments show that dichloromethane does not compete with water adsorption, because of size exclusion; the pure water vapor isotherm from literature provides an accurate representation...

  9. Passive Sampler for Measurements of Atmospheric Nitric Acid Vapor (HNO3 Concentrations

    Directory of Open Access Journals (Sweden)

    Andrzej Bytnerowicz

    2001-01-01

    Full Text Available Nitric acid (HNO3 vapor is an important nitrogenous air pollutant responsible for increasing saturation of forests with nitrogen and direct injury to plants. The USDA Forest Service and University of California researchers have developed a simple and inexpensive passive sampler for monitoring air concentrations of HNO3. Nitric acid is selectively absorbed on 47-mm Nylasorb nylon filters with no interference from particulate NO3-. Concentrations determined with the passive samplers closely corresponded with those measured with the co-located honeycomb annular denuder systems. The PVC protective caps of standardized dimensions protect nylon filters from rain and wind and allow for reliable measurements of ambient HNO3 concentrations. The described samplers have been successfully used in Sequoia National Park, the San Bernardino Mountains, and on Mammoth Mountain in California.

  10. Water Vapor Sorption Properties of Polyethylene Terephthalate over a Wide Range of Humidity and Temperature.

    Science.gov (United States)

    Dubelley, Florence; Planes, Emilie; Bas, Corine; Pons, Emmanuelle; Yrieix, Bernard; Flandin, Lionel

    2017-03-02

    The dynamic and equilibrium water vapor sorption properties of amorphous polyethylene terephthalate were determined via gravimetric analysis over a wide range of temperatures (23-70 °C) and humidities (0-90% RH). At low temperature and relative humidity, the dynamics of the sorption process was Fickian. Increasing the temperature or relative humidity induced a distinct up-swing effect, which was associated with a plasticization/clustering phenomenon. For high temperatures and relative humidity, a densification of the polymer was evidenced. In addition to the classical Fickian diffusion, a new parameter was introduced to express the structural modifications of PET. Finally, two partial pressures were defined as thresholds that control the transition between these three phases. A simplified state diagram was finally proposed. In addition, the thermal dependence of these sorption modes was also determined and reported. The enthalpy of Henry's water sorption and the activation energy of diffusion were independent of vapor pressure and followed an Arrhenius law.

  11. Theoretical study of adsorption of water vapor on surface of metallic uranium

    CERN Document Server

    Xiong Bi Tao; Xue Wei Dong; Zhu Zheng He; Jiang Gang; Wang Hong Yan; Gao Tao

    2002-01-01

    According to the experimental data, there is an intermediate substance that formed in the initial stage of oxidation reaction when water vapor is absorbed onto the metallic uranium. The minimum energy of UOH sub 2 witch C sub 2 subupsilon configuration is obtained in the state of sup 5 A sub 1 by B3LYP method of the density function theory (DFT), which is consistent with that by statics of atoms and molecules reaction (AMRS) and group theory. The results from calculations indicate that the adsorption of water vapor on the metallic uranium is an exothermic reaction and that the adsorbed amount decreases with the elevated temperatures. The adsorptive heat at 1 atm is -205.4747 kJ centre dot mol sup - sup 1 , which indicates a typical chemical adsorption

  12. Interaction of a sodium ion with the water liquid-vapor interface

    Science.gov (United States)

    Wilson, M. A.; Pohorille, A.; Pratt, L. R.; MacElroy, R. D. (Principal Investigator)

    1989-01-01

    Molecular dynamics results are presented for the density profile of a sodium ion near the water liquid-vapor interface at 320 K. These results are compared with the predictions of a simple dielectric model for the interaction of a monovalent ion with this interface. The interfacial region described by the model profile is too narrow and the profile decreases too abruptly near the solution interface. Thus, the simple model does not provide a satisfactory description of the molecular dynamics results for ion positions within two molecular diameters from the solution interface where appreciable ion concentrations are observed. These results suggest that surfaces associated with dielectric models of ionic processes at aqueous solution interfaces should be located at least two molecular diameters inside the liquid phase. A free energy expense of about 2 kcal/mol is required to move the ion within two molecular layers of the free water liquid-vapor interface.

  13. Water-vapor conductance of testudinian and crocodilian eggs (class reptilia).

    Science.gov (United States)

    Packard, G C; Taigen, T L; Packard, M J; Shuman, R D

    1979-09-01

    Flexible-shelled eggs of snapping turtles (Chelydra serpentina) have conductances to water vapor that are 55 times higher than predicted for avian eggs of similar size, whereas rigid-shelled eggs of softshell turtles (Trionyx spiniferus) and American alligators (Alligator mississippiensis) have conductances that are only five times higher than expected for comparable eggs of birds. The differences between empirical and predicted values result from the much higher effective pore areas in reptilian eggshells than in those of birds. The relatively high porosities of these reptilian eggs presumably facilitate the transport of oxygen and carbon dioxide eggshells in later stages of incubation when air trapped inside nest chambers may become hypoxic and hypercapnic, yet seem not to lead to excessive transpiration of water vapor owing to the high humidities in nests where incubation occurs.

  14. Vapor-liquid phase equilibria of water modelled by a Kim-Gordon potential

    Energy Technology Data Exchange (ETDEWEB)

    Maerzke, K A; McGrath, M J; Kuo, I W; Tabacchi, G; Siepmann, J I; Mundy, C J

    2009-03-16

    Gibbs ensemble Monte Carlo simulations were carried out to investigate the properties of a frozen-electron-density (or Kim-Gordon, KG) model of water along the vapor-liquid coexistence curve. Because of its theoretical basis, such a KG model provides for seamless coupling to Kohn-Sham density functional theory for use in mixed quantum mechanics/molecular mechanics (QM/MM) implementations. The Gibbs ensemble simulations indicate rather limited transferability of such a simple KG model to other state points. Specifically, a KG model that was parameterized by Barker and Sprik to the properties of liquid water at 300 K, yields saturated vapor pressures and a critical temperature that are significantly under- and over-estimated, respectively.

  15. Effect of Water Vapor on High-Temperature Corrosion under Conditions Mimicking Biomass Firing

    DEFF Research Database (Denmark)

    Okoro, Sunday Chukwudi; Montgomery, Melanie; Jappe Frandsen, Flemming

    2015-01-01

    The variable flue gas composition in biomass-fired plants, among other parameters, contributes to the complexityof high-temperature corrosion of materials. Systematic parameter studies are thus necessary to understand the underlyingcorrosion mechanisms. This paper investigates the effect of water...... atmospherecontaining either 3 or 13 vol % H2O vapor. Comprehensive characterization of the corrosion products was carried out by thecomplementary use of microscopic, spectroscopic, and diffraction-based techniques. To evaluate the effect of the exposure time,results were compared to previous results with longer...... isothermal exposure over 168 h and indicated that the development of aNi-rich layer as a result of selective attack was time-dependent. The increase in the water vapor decreased the measurablecorrosion attack, and in addition, decreased sulfation was observed. Results from the current investigation and from...

  16. Application of water vapor sorption measurements for porosity characterization of hardened cement pastes

    DEFF Research Database (Denmark)

    Wu, Min; Johannesson, Björn; Geiker, Mette Rica

    2014-01-01

    Water vapor sorption can be used to study important properties of porous materials including specific surface area and pore size distribution (PSD). However, the data analysis is somewhat inconsistent in literature. In this work, the important factors influencing the analyzed results using sorption...... data were reviewed. Water vapor sorption measurements were then applied to two hardened cement pastes and one model porous material MCM-41. The specific surface area was calculated based on different equations accounting for multilayer adsorption and the PSD was analyzed from both the absorption...... and the desorption isotherms for comparison: The calculated specific surface area was quite dependent on which equation is considered for multilayer adsorption. For the studied hardened cement pastes, three characteristic peaks were found in the calculated PSD curves from the desorption isotherms with corresponding...

  17. Investigating the effects of methanol-water vapor mixture on a PBI-based high temperature PEM fuel cell

    DEFF Research Database (Denmark)

    Araya, Samuel Simon; Andreasen, Søren Juhl; Nielsen, Heidi Venstrup

    2012-01-01

    This paper investigates the effects of methanol and water vapor on the performance of a high temperature proton exchange membrane fuel cell (HT-PEMFC). A H3PO4-doped polybenzimidazole (PBI) membrane electrode assembly (MEA), Celtec P2100 of 45 cm2 of active surface area from BASF was employed....... A long-term durability test of around 1250 h was performed, in which the concentrations of methanol-water vapor mixture in the anode feed gas were varied. The fuel cell showed a continuous performance decay in the presence of vapor mixtures of methanol and water of 5% and 8% by volume in anode feed...

  18. Short-range precipitation forecasts using assimilation of simulated satellite water vapor profiles and column cloud liquid water amounts

    Science.gov (United States)

    Wu, Xiaohua; Diak, George R.; Hayden, Cristopher M.; Young, John A.

    1995-01-01

    These observing system simulation experiments investigate the assimilation of satellite-observed water vapor and cloud liquid water data in the initialization of a limited-area primitive equations model with the goal of improving short-range precipitation forecasts. The assimilation procedure presented includes two aspects: specification of an initial cloud liquid water vertical distribution and diabatic initialization. The satellite data is simulated for the next generation of polar-orbiting satellite instruments, the Advanced Microwave Sounding Unit (AMSU) and the High-Resolution Infrared Sounder (HIRS), which are scheduled to be launched on the NOAA-K satellite in the mid-1990s. Based on cloud-top height and total column cloud liquid water amounts simulated for satellite data a diagnostic method is used to specify an initial cloud water vertical distribution and to modify the initial moisture distribution in cloudy areas. Using a diabatic initialization procedure, the associated latent heating profiles are directly assimilated into the numerical model. The initial heating is estimated by time averaging the latent heat release from convective and large-scale condensation during the early forecast stage after insertion of satellite-observed temperature, water vapor, and cloud water formation. The assimilation of satellite-observed moisture and cloud water, together withy three-mode diabatic initialization, significantly alleviates the model precipitation spinup problem, especially in the first 3 h of the forecast. Experimental forecasts indicate that the impact of satellite-observed temperature and water vapor profiles and cloud water alone in the initialization procedure shortens the spinup time for precipitation rates by 1-2 h and for regeneration of the areal coverage by 3 h. The diabatic initialization further reduces the precipitation spinup time (compared to adiabatic initialization) by 1 h.

  19. Managing the Drivers of Air Flow and Water Vapor Transport in Existing Single-Family Homes

    Energy Technology Data Exchange (ETDEWEB)

    Cummings, James [Building America Partnership for Improved Residential Construction (BA-PIRC), Cocoa, FL (United States); Withers, Charles [Building America Partnership for Improved Residential Construction (BA-PIRC), Cocoa, FL (United States); Martin, Eric [Building America Partnership for Improved Residential Construction (BA-PIRC), Cocoa, FL (United States); Moyer, Neil [Building America Partnership for Improved Residential Construction (BA-PIRC), Cocoa, FL (United States)

    2012-10-01

    This report is a revision of an earlier report titled: Measure Guideline: Managing the Drivers of Air Flow and Water Vapor Transport in Existing Single-Family Homes. Revisions include: Information in the text box on page 1 was revised to reflect the most accurate information regarding classifications as referenced in the 2012 International Residential Code. “Measure Guideline” was dropped from the title of the report. An addition was made to the reference list.

  20. Managing the Drivers of Air Flow and Water Vapor Transport in Existing Single Family Homes (Revised)

    Energy Technology Data Exchange (ETDEWEB)

    Cummings, J.; Withers, C.; Martin, E.; Moyer, N.

    2012-10-01

    This document focuses on managing the driving forces which move air and moisture across the building envelope. While other previously published Measure Guidelines focus on elimination of air pathways, the ultimate goal of this Measure Guideline is to manage drivers which cause air flow and water vapor transport across the building envelope (and also within the home), control air infiltration, keep relative humidity (RH) within acceptable limits, avoid combustion safety problems, improve occupant comfort, and reduce house energy use.

  1. The origin of water-vapor rings in tropical cold pools

    Science.gov (United States)

    Langhans, W.; Romps, D. M.

    2014-12-01

    An invigoration of deep convection by cold pools is supported by two conceptually different theories: a) mechanic lifting of air-parcels at the cold-pool boundary and b) thermodynamic preconditioning of boundary-layer air due to rings of enhanced water-vapor content (~ +1 g/kg). The latter have been associated with the leading edges of radially spreading cold pools in studies of precipitating convection over tropical oceans. Even recovered cold pools exhibit these moisture anomalies and the formation of such rings thus also plays a critical role in theory (a) through the moistening of ambient air that is later lifted by another cold-pool. Despite the described relevance, the origin of these water-vapor rings is unclear. This motivates us to conduct idealized large-eddy simulations with the purpose of explaining the origin of these water-vapor rings. The simulations are coupled with a recently designed framework to track Lagrangian water particles and allows us to decompose the emerging vapor distribution according to its origin. The emerging quasi-axisymmetric flow transitions from a vortex-dominated downdraft in the early stage to a radial gravity current in the later stage. Preliminary results highlight the dominating role of moisture that resides in the boundary layer before deep convection is initiated. A delineation of the individual contributions from boundary-layer moisture, evaporated hydrometeors, and latent heat fluxes reveals that the latter two sources may not be crucial for the anomalous moisture content over the radial distances considered. The sensitivity to the initial moisture of the boundary-layer and the effects of entrainment into the cold pool will be discussed.

  2. Thin cuprous oxide films prepared by thermal oxidation of copper foils with water vapor

    Energy Technology Data Exchange (ETDEWEB)

    Liang Jianbo, E-mail: liangjienbo1980@yahoo.co.jp [Department of Frontier Materials,Nagoya Institute of Technology, Nagoya 4668555 (Japan); Kishi, Naoki; Soga, Tetsuo [Department of Frontier Materials,Nagoya Institute of Technology, Nagoya 4668555 (Japan); Jimbo, Takashi [Research Center for Nano-Device and System, Nagoya Institute of Technology, Nagoya 4668555 (Japan); Ahmed, Mohsin [Department of Frontier Materials,Nagoya Institute of Technology, Nagoya 4668555 (Japan)

    2012-01-31

    We present an improved preparation method for the growth of high quality crystals of cuprous oxide films grown by thermal oxidation of cupper foils with water vapor. This method proved to be good for preparing cuprous oxide films with high purity and large grain size. X-ray diffraction studies revealed the formation of Cu{sub 2}O films with preferred (111) orientation. The cuprous oxide diodes fabricated by the above technique have been studied using current-voltage method.

  3. THE THEORETICAL CRITERIA ON THE VAPORIZATION AND COMBUSTION RATES OF EMULSIONS WATER IN HEAVY FUEL OIL

    Directory of Open Access Journals (Sweden)

    Corneliu MOROIANU

    2012-05-01

    Full Text Available The vaporization and combustion characteristics of a heavy oil-water emulsion droplet are investigated with graphological method. The combustion graphology of fuel oils is defined as a new technical and scientific field which deals with the graphic transposition of the processes of fuels combustion development in a simulator. Thus, it is easy to establish the ignition-combustion characteristics, including the laws that govern their changes depending on the combustion conditions and fuel specifications

  4. Water vapor flow and high thermal resistance insulation systems for metal buildings

    Energy Technology Data Exchange (ETDEWEB)

    Kelso, R.M.

    1983-01-01

    In response to increasing energy costs, high thermal resistance insulation systems are being marketed for pre-engineered metal buildings. Historically, blanket insulation has been installed between the skin and the structure of these buildings. The new insulation systems generally are installed inside the structure; thus the structure is colder and, unless an effective retarder is included, water vapor condensation problems can result. While the vapor permeance of various insulation facing materials is documented, the effect of such field conditions as seams and penetrations is less well known. Permeance tests were performed on samples of foil-kraft paper insulation facing with two seams and two penetration configurations. The tests show that seams can multiply the permeance of the vapor retarder by factors of 1.2 or more and penetrations can multiply the permeance by 3 or more. The theory of vapor flow analysis is reviewed and compared with the test results and presented graphically. Possible applications and suggestions for further investigation are discussed.

  5. Water vapor flow and high thermal resistance insulation systems for metal buildings

    Energy Technology Data Exchange (ETDEWEB)

    Kelso, R.M.

    1981-12-01

    In response to increasing energy costs, high thermal resistance insulation systems are being marketed for pre-engineered metal buildings. Historically, blanket insulation has been installed between the skin and the structure of these buildings. The new insulation systems generally are installed inside the structure; thus the structure is colder and, unless an effective retarder is included, water vapor condensation problems can result. While the vapor permeance of various insulation facing materials is documented, the effect of such field conditions as seams and penetrations is less well known. Permeance tests were performed on samples of foil-kraft paper insulation facing with two seams and two penetration configurations. The tests show that seams can multiply the permeance of the vapor retarder by factors of 1.2 or more and penetrations can multiply the permeance by 3 or more. The theory of vapor flow analysis is reviewed and compared with the test results and presented graphically. Possible applications and suggestions for further investigation are discussed.

  6. On the Electronic Nature of the Surface Potential at the Vapor-Liquid Interface of Water

    Energy Technology Data Exchange (ETDEWEB)

    Kathmann, S M; Kuo, I; Mundy, C J

    2008-02-05

    The surface potential at the vapor-liquid interface of water is relevant to many areas of chemical physics. Measurement of the surface potential has been experimentally attempted many times, yet there has been little agreement as to its magnitude and sign (-1.1 to +0.5 mV). We present the first computation of the surface potential of water using ab initio molecular dynamics. We find that the surface potential {chi} = -18 mV with a maximum interfacial electric field = 8.9 x 10{sup 7} V/m. A comparison is made between our quantum mechanical results and those from previous molecular simulations. We find that explicit treatment of the electronic density makes a dramatic contribution to the electric properties of the vapor-liquid interface of water. The E-field can alter interfacial reactivity and transport while the surface potential can be used to determine the 'chemical' contribution to the real and electrochemical potentials for ionic transport through the vapor-liquid interface.

  7. Compact Reconnaissance Imaging Spectrometer Observations of Water Vapor and Carbon Monoxide

    Science.gov (United States)

    Smith, Michael D.; Wolff, Michael J.; Clancy, R. Todd; Murchie, Scott L.

    2009-01-01

    The Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) onboard the Mars Reconnaissance Orbiter (MRO) spacecraft began taking observations in September 2006 and has now collected more than a full Martian year of data. Retrievals performed using the near-infrared spectra obtained by CRISM are used to characterize the seasonal and spatial variation of the column abundance of water vapor and the column-averaged mixing ratio of carbon monoxide. CRISM retrievals show nominal behavior in water vapor during northern hemisphere spring and summer with maximum abundance reaching 50 precipitable micrometers. Water vapor abundance during the southern hemisphere spring and summer appears significantly reduced compared to observations by other instruments taken during previous years. The CRISM retrievals show the seasonally and globally averaged carbon monoxide mixing ratio to be 700 ppm, but with strong seasonal variations at high latitudes. The summertime near-polar carbon monoxide mixing ratio falls to 200 ppm in the south and 400 ppm in the north as carbon dioxide sublimates from the seasonal polar ice caps and dilutes noncondensable species including carbon monoxide. At low latitudes, the carbon monoxide mixing ratio varies in response to the mean seasonal cycle of surface pressure.

  8. Evaluation of tropospheric water vapor profiling using eye-safe, infrared differential absorption lidar

    Energy Technology Data Exchange (ETDEWEB)

    Rye, B.J. [Colorado Univ., Boulder, CO (United States). Cooperative Inst. for Research in Environmental Sciences]|[National Oceanic and Atmospheric Administration, Boulder, CO (United States). Environmental Technology Lab.; Machol, J.L.; Grund, C.J.; Hardesty, R.M. [National Oceanic and Atmospheric Administration, Boulder, CO (United States). Environmental Technology Lab.

    1996-05-14

    Continuous, high quality profiles of water vapor, free of systematic bias, and of moderate temporal and spatial resolution are fundamental to the success of the ARM CART program. In addition, these should be acquired over long periods at low operational and maintenance cost. The development and verification of realistic climate model parameterizations for clouds and net radiation balance, and the correction of other CART site sensor observations for interferences due to the presence of water vapor are critically dependent on water vapor profile measurements. To date, application of profiles have been limited by vertical resolution and uniqueness and high operating cost, or diminished daytime performance, lack of eye-safety, and high maintenance cost. Recent developments in infrared laser and detector technology make possible compact IR differential absorption lidar (DIAL) systems at eye-safe wavelengths. In the studies reported here, we develop DIAL system performance models and examine the potential of solving some of the shortcomings of previous methods using parameters representative of current technologies. These simulations are also applied to determine the strengths and weaknesses unique to the DIAL method for this application.

  9. Water vapor transport in the lower mesosphere of the subtropics: a trajectory analysis

    Science.gov (United States)

    Flury, T.; Müller, S. C.; Hocke, K.; Kämpfer, N.

    2008-07-01

    The Institute of Applied Physics operates an airborne microwave radiometer that measures the rotational transition line of water vapor at 183.3 GHz. Measurements were acquired on board a Learjet once a year in the period 1998 to 2006. Water vapor profiles are retrieved for the altitude range from 15 to 75 km along the flight track. We report on a water vapor enhancement in the lower mesosphere above India and the Arabic Sea measured on our flight mission in November 2005 conducted during EC-project SCOUT-O3. The flight led from Switzerland to Australia and back. We find an enhancement of up to 25% in the lower mesospheric H2O volume mixing ratio measured on the return flight one week after the outward flight. The origin of the air is traced back by means of a trajectory model in the lower mesosphere. During the outward flight the air came from the Carribean and crossed the Atlantic Ocean. On the return flight the air came from China and orginated from mid latitudes. Thus the large variability of H2O VMR during our flight is explained by a change of the winds in the lower mesosphere.

  10. Assessing the ability of isotope-enabled General Circulation Models to simulate the variability of Iceland water vapor isotopic composition

    Science.gov (United States)

    Erla Sveinbjornsdottir, Arny; Steen-Larsen, Hans Christian; Jonsson, Thorsteinn; Ritter, Francois; Riser, Camilla; Messon-Delmotte, Valerie; Bonne, Jean Louis; Dahl-Jensen, Dorthe

    2014-05-01

    During the fall of 2010 we installed an autonomous water vapor spectroscopy laser (Los Gatos Research analyzer) in a lighthouse on the Southwest coast of Iceland (63.83°N, 21.47°W). Despite initial significant problems with volcanic ash, high wind, and attack of sea gulls, the system has been continuously operational since the end of 2011 with limited down time. The system automatically performs calibration every 2 hours, which results in high accuracy and precision allowing for analysis of the second order parameter, d-excess, in the water vapor. We find a strong linear relationship between d-excess and local relative humidity (RH) when normalized to SST. The observed slope of approximately -45 o/oo/% is similar to theoretical predictions by Merlivat and Jouzel [1979] for smooth surface, but the calculated intercept is significant lower than predicted. Despite this good linear agreement with theoretical calculations, mismatches arise between the simulated seasonal cycle of water vapour isotopic composition using LMDZiso GCM nudged to large-scale winds from atmospheric analyses, and our data. The GCM is not able to capture seasonal variations in local RH, nor seasonal variations in d-excess. Based on daily data, the performance of LMDZiso to resolve day-to-day variability is measured based on the strength of the correlation coefficient between observations and model outputs. This correlation coefficient reaches ~0.8 for surface absolute humidity, but decreases to ~0.6 for δD and ~0.45 d-excess. Moreover, the magnitude of day-to-day humidity variations is also underestimated by LMDZiso, which can explain the underestimated magnitude of isotopic depletion. Finally, the simulated and observed d-excess vs. RH has similar slopes. We conclude that the under-estimation of d-excess variability may partly arise from the poor performance of the humidity simulations.

  11. The Sensitivity of Atmospheric Water Isotopes to Entrainment and Precipitation Efficiency in a Bulk Plume Model of Convection

    Science.gov (United States)

    Duan, S.; Wright, J. S.; Romps, D. M.

    2016-12-01

    Atmospheric water isotopes have been proposed as potentially powerful constraints on the physics of convective clouds and parameterizations of convective processes in models. We have previously derived an analytical model of water vapor (H2O) and one of its heavy isotopes (HDO) in convective environments based on a bulk-plume convective water budget in radiative convective equilibrium. This analytical model provides a useful starting point for examining the joint responses of water vapor and its isotopic composition to changes in convective parameters; however, certain idealistic assumptions are required to make the model analytically solvable. Here, we develop a more flexible numerical framework that enables a wider range of model configurations and includes additional isotopic tracers. This model provides a bridge between Rayleigh distillation, which is simple but inflexible, and more complicated convection schemes and cloud resolving models, which are more realistic but also more difficult to perturb and interpret. Application of realistic in-cloud water profiles in our model produces vertical distributions of δD that qualitatively match satellite observations from the Tropospheric Emission Spectrometer (TES). We test the sensitivity of water vapor and its isotopic composition to a wide range of perturbations in the model parameters and their vertical profiles. In this presentation, we focus especially on establishing constraints for convective entrainment and precipitation efficiency. We conclude by discussing the potential application of this model as part of a larger water isotope toolkit for use with offline diagnostics provided by reanalyses and GCMs.

  12. High explosives vapor detection by atmospheric sampling glow discharge ionization/tandem mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    McLuckey, S.A.; Goeringer, D.E.; Asano, K.G. [Oak Ridge National Lab., TN (United States). Chemical and Analytical Sciences Div.

    1996-02-01

    The combination of atmospheric sampling glow discharge ionization with tandem mass spectrometry for the detection of traces of high explosives is described. Particular emphasis is placed on use of the quadrupole ion trap as the type of tandem mass spectrometer. Atmospheric sampling glow discharge provides a simple, rugged, and efficient means for anion formation while the quadrupole ion trap provides for efficient tandem mass spectrometry. Mass selective ion accumulation and non-specific ion activation methods can be used to overcome deleterious effects arising from ion/ion interactions. Such interactions constitute the major potential technical barrier to the use of the ion trap for real-time monitoring of targeted compounds in uncontrolled and highly variable matrices. Tailored waveforms can be used to effect both mass selective ion accumulation and ion activation. Concatenated tailored waveforms allow for both functions in a single experiment thereby providing the capability for monitoring several targeted species simultaneously. The combination of atmospheric sampling glow discharge ionization with a state-of-the-art analytical quadrupole ion trap is a highly sensitive and specific detector for traces of high explosives. The combination is also small and inexpensive relative to virtually any other form of tandem mass spectrometry. The science and technology underlying the glow discharge/ion trap combination is sufficiently mature to form the basis for an engineering effort to make the detector portable. 85 refs.

  13. Tropospheric and Boundary-Layer Water Vapor Isotopes over the Boreal Forest and Mediterranean Sea: Validation of Aura Tropospheric Emission Spectrometer Retrievals of HDO and H2O

    Science.gov (United States)

    Herman, R. L.; Cherry, J. E.; Young, J. M.; Welker, J. M.; Noone, D. C.; Sodemann, H.; Worden, J.

    2013-12-01

    Water vapor and HDO retrievals from the Tropospheric Emission Spectrometer (TES) on the EOS Aura platform have been compared with nearly coincident in situ airborne measurements. These measurements were made with commercially available Picarro L2130-I isotopic water analyzers on aircraft platforms over in the Alaskan Boreal forest interior during summers of 2011 and 2012, as well as aircraft measurements over the Mediterranean Sea near Sicily in 2012. TES Transect special observations were utilized in these comparisons. The TES averaging kernels and a priori constraints have been applied to the in situ data, using water vapor constraint vectors from GMAO GEOS-5 analyses for Version Five (V005) of TES data. TES calculated errors are compared with the rms (root mean square) of scan-to-scan variability to assess how much of the variability is attributable to TES observation error. Spatial and temporal variations are assessed from the in situ aircraft measurements. Over Alaska, a significant portion of the scan-to-scan variability is due to this atmospheric heterogeneity and vertical mixing. This variability was not observed over the Mediterranean and suggest that the water vapor isotope flux (primarily transpiration) from the vegetated surface of the Boreal contributes to the vertical heterogeneity from the upper to the lower atmosphereof the troposphere. The TES V005 bias in HDO/H2O will be reported in this presentation.

  14. Oscillations in atmospheric water above Switzerland

    Science.gov (United States)

    Hocke, Klemens; Navas-Guzmán, Francisco; Moreira, Lorena; Bernet, Leonie; Mätzler, Christian

    2017-10-01

    Cloud fraction (CF), integrated liquid water (ILW) and integrated water vapour (IWV) were continuously measured from 2004 to 2016 by the TROpospheric WAter RAdiometer (TROWARA) in Bern, Switzerland. There are indications for interannual variations of CF and ILW. A spectral analysis shows that IWV is dominated by an annual oscillation, leading to an IWV maximum of 24 kg m-2 in July to August and a minimum of 8 kg m-2 in February. The seasonal behaviour of CF and ILW is composed by both the annual and the semiannual oscillation. However, the annual oscillation of CF has a maximum in December while the annual oscillation of ILW has a maximum in July. The semiannual oscillations of CF and ILW are strong from 2010 to 2014. The normalized power spectra of ILW and CF show statistically significant spectral components with periods of 76, 85, 97 and 150 days. We find a similarity between the power spectra of ILW and CF with those of zonal wind at 830 hPa (1.5 km) above Bern. Particularly, the occurrence of higher harmonics in the CF and ILW spectra is possibly forced by the behaviour of the lower-tropospheric wind. The mean amplitude spectra of CF, ILW and IWV show increased short-term variability on timescales less than 40 days from spring to fall. We find a weekly cycle of CF and ILW from June to September with increased values on Saturday, Sunday and Monday.

  15. Three-dimensional vapor intrusion modeling approach that combines wind and stack effects on indoor, atmospheric, and subsurface domains.

    Science.gov (United States)

    Shirazi, Elham; Pennell, Kelly G

    2017-12-13

    Vapor intrusion (IV) exposure risks are difficult to characterize due to the role of atmospheric, building and subsurface processes. This study presents a three-dimensional VI model that extends the common subsurface fate and transport equations to incorporate wind and stack effects on indoor air pressure, building air exchange rate (AER) and indoor contaminant concentration to improve VI exposure risk estimates. The model incorporates three modeling programs: (1) COMSOL Multiphysics to model subsurface fate and transport processes, (2) CFD0 to model atmospheric air flow around the building, and (3) CONTAM to model indoor air quality. The combined VI model predicts AER values, zonal indoor air pressures and zonal indoor air contaminant concentrations as a function of wind speed, wind direction and outdoor and indoor temperature. Steady state modeling results for a single-story building with a basement demonstrate that wind speed, wind direction and opening locations in a building play important roles in changing the AER, indoor air pressure, and indoor air contaminant concentration. Calculated indoor air pressures ranged from approximately -10 Pa to +4 Pa depending on weather conditions and building characteristics. AER values, mass entry rates and indoor air concentrations vary depending on weather conditions and building characteristics. The presented modeling approach can be used to investigate the relationship between building features, AER, building pressures, soil gas concentrations, indoor air concentrations and VI exposure risks.

  16. Atmospheric radio refractivity and water vapour density at Oshodi ...

    African Journals Online (AJOL)

    ... columnar water vapour density ρ can be used to estimate N over Oshodi, and Kano. For instance, line of regression of N upon ρ for Oshodi at the 0-3km atmospheric column is N = (4.93 ± 0.75) ρ + 254.15 ± 11.26. Keywords: atmospheric humidity, columnar radio refractivity. Nigeria Journal of Pure and Applied Physics Vol ...

  17. Undoped and in-situ B doped GeSn epitaxial growth on Ge by atmospheric pressure-chemical vapor deposition

    DEFF Research Database (Denmark)

    Vincent, B.; Gencarelli, F.; Bender, H.

    2011-01-01

    In this letter, we propose an atmospheric pressure-chemical vapor deposition technique to grow metastable GeSn epitaxial layers on Ge. We report the growth of defect free fully strained undoped and in-situ B doped GeSn layers on Ge substrates with Sit contents up to 8%. Those metastable layers stay...

  18. Modeling the impact of vapor thymol concentration, temperature and modified atmosphere condition on growth behavior of Salmonella spp. on raw shrimp

    Science.gov (United States)

    Salmonella spp. is a microorganism of concern, on a global basis, for raw shrimp. This research modeled the impact of vapor thymol concentration (0, 0.8 and 1.6 mg/l), storage temperature (8, 12 and 16 degree C) and modified atmosphere packaging (0.04 and 59.5 percent CO2) against the growth behavio...

  19. Desalination of water by vapor-phase transport through hydrophobic nanopores

    Science.gov (United States)

    Lee, Jongho; Karnik, Rohit

    2010-08-01

    We propose a new approach to desalination of water whereby a pressure difference across a vapor-trapping nanopore induces selective transport of water by isothermal evaporation and condensation across the pore. Transport of water through a nanopore with saline water on one side and pure water on the other side under a pressure difference was theoretically analyzed under the rarefied gas assumption using a probabilistic framework that accounts for diffuse scattering from the pore walls as well as reflection from the menisci. The analysis revealed that in addition to salinity, temperature, and pressure difference, the nanopore aspect ratio and the probability of condensation of a water molecule incident on a meniscus from the vapor phase, known as the condensation coefficient, are key determinants of flux. The effect of condensation coefficient on mass flux becomes critical when the aspect ratio is small. However, the mass flux becomes independent of the condensation coefficient as the pore aspect ratio increases, converging to the Knudsen flux for long nanopores. For design of a nanopore membrane that can trap vapor, a minimum aspect ratio is derived for which coalescence of the two interfaces on either side of the nanopore remains energetically unfavorable. Based on this design criterion, the analysis suggests that mass flux in the range of 20-70 g/m2 s may be feasible if the system is operated at temperatures in the range of 30-50 °C. The proposed approach further decouples transport properties from material properties of the membrane, which opens the possibility of engineering membranes with appropriate materials that may lead to reverse osmosis membranes with improved flux, better selectivity, and high chlorine resistance.

  20. Computational investigations of streamers in a single bubble suspended in distilled water under atmospheric pressure conditions

    Science.gov (United States)

    Sharma, Ashish; Levko, Dmitry; Raja, Laxminarayan

    2016-09-01

    We present a computational model of nanosecond streamers generated in helium bubbles immersed in distilled water at the atmospheric pressure conditions. The model is based on the self-consistent, multispecies and the continuum description of plasma and takes into account the presence of water vapor in the gas bubble for a more accurate description of the kinetics of the discharge. We find that the dynamic characteristics of the streamer discharge are completely different at low and high over voltages. We observe that the polarity of the trigger voltage has a substantial effect on initiation, transition and evolution stages of streamers with the volumetric distribution of species in the streamer channel much more uniform for negative trigger voltages due to the presence of multiple streamers. We also find that the presence of water vapor significantly influences the distribution of the dominant species in the streamer trail and has a profound effect on the flux of the dominant species to the bubble wall. The research reported in this publication was supported by Competitive Research Funding from King Abdullah University of Science and Technology (KAUST).

  1. Precipitable water vapor characterization in the coastal regions of China based on ground-based GPS

    Science.gov (United States)

    Wang, Zhaoyang; Zhou, Xinghua; Liu, Yanxiong; Zhou, Dongxu; Zhang, Huayi; Sun, Weikang

    2017-12-01

    Water vapor plays an important role in climate change; thus, studying the spatial distribution and temporal variation of precipitable water vapor (PWV) in the coastal regions of China would help researchers to understand the climate characteristics of those regions. In this paper, 6-year 1-h interval PWV were derived from 27 Global Positioning System stations observations of Chinese coastal GPS observation network, surface meteorological data and European Center for Medium-Range Weather Forecasts (ERA-Interim) reanalysis products. The present study provides the use of these data to investigate the spatial-temporal variability of water vapor throughout the coastal regions of China. Latitude is the main factor affecting the spatial distribution of GPS-derived PWV; that is, PWV decreased by about 1.5 mm for each 1° increase of latitude. For regions at the same latitude, a region that is relatively close to the ocean will have a higher content of PWV. The PWV in the southeastern and southwestern coastal regions of China is significantly higher in summer; this may be influenced by the southeastern and southwestern water vapor inflow corridors. The PWV obviously varies monthly, reaching a minimum in January; however, the timing of the maximum varied but usually appeared in June, July or August and was affected by the monsoons. The PWV varies largely between summer and winter with a larger gradient of change in PWV with latitude in winter than in summer. The positive correlation coefficient between PWV and the surface temperature varied in different seasons; this is related to the changes of temperature and the horizontal motion of water vapor. Use of the Fast Fourier Transform method showed that the PWV time series data have multi-scale characteristics. The amplitude and phase of the PWV time series in annual, semiannual, four month and seasonal cycles were extracted through harmonic wave analysis. The amplitude of four month and seasonal cycles did not pass

  2. Oscillations in atmospheric water above Switzerland

    Directory of Open Access Journals (Sweden)

    K. Hocke

    2017-10-01

    Full Text Available Cloud fraction (CF, integrated liquid water (ILW and integrated water vapour (IWV were continuously measured from 2004 to 2016 by the TROpospheric WAter RAdiometer (TROWARA in Bern, Switzerland. There are indications for interannual variations of CF and ILW. A spectral analysis shows that IWV is dominated by an annual oscillation, leading to an IWV maximum of 24 kg m−2 in July to August and a minimum of 8 kg m−2 in February. The seasonal behaviour of CF and ILW is composed by both the annual and the semiannual oscillation. However, the annual oscillation of CF has a maximum in December while the annual oscillation of ILW has a maximum in July. The semiannual oscillations of CF and ILW are strong from 2010 to 2014. The normalized power spectra of ILW and CF show statistically significant spectral components with periods of 76, 85, 97 and 150 days. We find a similarity between the power spectra of ILW and CF with those of zonal wind at 830 hPa (1.5 km above Bern. Particularly, the occurrence of higher harmonics in the CF and ILW spectra is possibly forced by the behaviour of the lower-tropospheric wind. The mean amplitude spectra of CF, ILW and IWV show increased short-term variability on timescales less than 40 days from spring to fall. We find a weekly cycle of CF and ILW from June to September with increased values on Saturday, Sunday and Monday.

  3. GOZCARDS Source Data for Water Vapor Monthly Zonal Means on a Geodetic Latitude and Pressure Grid V1.01

    Data.gov (United States)

    National Aeronautics and Space Administration — The GOZCARDS Source Data for Water Vapor Monthly Zonal Averages on a Geodetic Latitude and Pressure Grid product (GozSmlpH2O) contains zonal means and related...

  4. GOZCARDS Merged Data for Water Vapor Monthly Zonal Means on a Geodetic Latitude and Pressure Grid V1.01

    Data.gov (United States)

    National Aeronautics and Space Administration — The GOZCARDS Merged Data for Water Vapor Monthly Zonal Averages on a Geodetic Latitude and Pressure Grid product (GozMmlpH2O) contains zonal means and related...

  5. Continuous Water Vapor Mass Flux and Temperature Measurements in a Model Scramjet Combustor Using a Diode Laser Sensor

    National Research Council Canada - National Science Library

    Upschulte, B. L; Miller, M. F; Allen, M. G; Jackson, K; Gruber, M; Mathur, T

    1998-01-01

    A sensor for simultaneous measurements of water vapor density, temperature and velocity has been developed based on absorption techniques using room temperature diode lasers (InGaAsP) operating at 1.31 micrometers...

  6. MODIS/Terra Total Precipitable Water Vapor 5-Min L2 Swath 1km and 5km V006

    Data.gov (United States)

    National Aeronautics and Space Administration — This Level 2 data collection contains derived precipitable column water vapor amounts, during daytime using a near-infrared over clear land areas and above clouds...

  7. MODIS/Aqua Total Precipitable Water Vapor 5-Min L2 Swath 1km and 5km V005 NRT

    Data.gov (United States)

    National Aeronautics and Space Administration — This Level 2 data collection contains derived precipitable column water vapor amounts, during daytime using a near-infrared over clear land areas and above clouds...

  8. MODIS/Terra Total Precipitable Water Vapor 5-Min L2 Swath 1km and 5km V005 NRT

    Data.gov (United States)

    National Aeronautics and Space Administration — This Level 2 data collection contains derived precipitable column water vapor amounts, during daytime using a near-infrared over clear land areas and above clouds...

  9. Vapor-Liquid Equilibrium of Methane with Water and Methanol. Measurements and Modeling

    DEFF Research Database (Denmark)

    Frost, Michael Grynnerup; Karakatsani, Eirini; von Solms, Nicolas

    2014-01-01

    There is a need for high-quality experimental phase equilibrium data in the petroleum and chemical industries, for example, mixtures of oil and gas with gas hydrate inhibitors (methanol, glycols) and organic acids. This includes a wide range of different systems, which all deal with processes...... that rely on phase equilibrium data for optimization. The objective of this work is to provide experimental data for hydrocarbon systems with polar chemicals such as alcohols, glycols, and water. New vapor-liquid equilibrium data are reported for methane + water, methane + methanol, and methane + methanol...

  10. Evaluation of Water Vapor Sorption Hysteresis in Soils: The Role of Organic Matter and Clay

    DEFF Research Database (Denmark)

    Arthur, Emmanuel; Tuller, Markus; Moldrup, Per

    2015-01-01

    Hysteresis of the soil water characteristic (SWC) has been extensively studied for matric potentials between zero and −1.5 MPa. However, little information is available on how to quantify, evaluate, and identify the causes of hysteresis at potentials below −10 MPa where vapor sorption plays...... an important role. It is clear that modeling physical and biological soil processes is more accurate when SWC hysteresis is considered, particularly at low potentials where small differences in water content are associated with large changes in potential energy. The objectives of the presented study were to...

  11. Electrical characteristics and hydrogen concentration of chemical vapor deposited silicon dioxide films: Effect of water treatment

    Science.gov (United States)

    Li, S. C.; Murarka, S. P.

    1992-11-01

    The effect of exposing chemical vapor deposited silicon dioxide directly to water has been investigated. Unlike the effect of the water-related traps in thermally grown silicon dioxide, the capacitance-voltage (C-V) shift due to diffused-in water molecules is directly observed without using the method of avalanche injection. The resonate nuclear reaction technique with 15N ion beam has been used to measure the hydrogen concentration of water-boiled, as-deposited, and rapid thermal-annealed silicon dioxide films. These depth profiles show that the hydrogen-containing species, that are most likely water molecules, diffuse in and out and redistribute in the as-deposited and rapid thermal-annealed films. These hydrogen depth profiles also indicate that the amount of diffused-in water molecules in the oxide is limited by the solubility of the water in the oxide. The solubility of water in the oxide annealed at high temperatures is found to be significantly lower than that in the as-deposited oxide. It is found that diffused-in water molecules, in order to satisfy the water solubility of the oxide, play a compensating role in controlling the oxide charges. Water molecules would continue to diffuse in, and interact with oxide charges and produce charges with reverse polarity that compensate the existing oxide charges until water solubility is satisfied.

  12. Heat and Mass Diffusions in the Absorption of Water Vapor by Aqueous Solution of Lithium Bromide

    Science.gov (United States)

    Kashiwagi, Takao; Kurosaki, Yasuo; Nikai, Isao

    The recent development of absorption-type heat pump is highly essential from the viewpoint of extracting the effective energy from waste heat or solar energy. To increase the efficiency of energy conversion, it is important to improve the performance of absorbers. The objective of this paper is to obtain an increased understanding of the fine mechanisms of vapor absorption. A system combining holographic interferometry wity thermometry is adopted to observe the progress of one-dimensional water vapor absorption by aqueous solution of lithium bromide (LiBr) and also to measure the unsteady temperature and concentration distributions in the absorption process. The experiments are carried out under the condition that the solution surface is exposed to the saturated water vapor at reduced pressure, and the effects of LiBr mass concentration on absorption mechanism are examined in the concentration range 20-60 mass%. The interference fringes are analyzed to distinguish between the layers of heat conduction and mass diffusion. The temperature and concentration distributions thus determined experimentally are compared with numerical solutions obtained by the equations for unsteady heat conduction and mass diffusion taking into consideration the effect of heat by dilution, to give reasonable values of mass diffusivity hitherto remaining unknown. Especially in the range of 40-60 mass%, the mass diffusivity decreases extremely with the increase of mass concentration of LiBr and it falls down to 0.7-0.8×10-9 m2/s in case of 60 mass% solution.

  13. Antarctic measurements of ozone, water vapor, and aerosol extinction by Sage 2 in the spring of 1987

    Science.gov (United States)

    Larsen, J. C.; Mccormick, M. Patrick

    1988-01-01

    Recent measurements of ozone, water vapor, and aerosol extinction from the spring of 1987 are presented and compared to 1985 and 1986. The observed changes to variations in meteorological conditions in the vortex for these three years are noted. March ozone data at similar latitudes for these three years will be used to investigate coupling between severity of the springtime depletion and early fall values. Researchers also investigate correlations between the measured species of water vapor, ozone, and aerosols throughout the vortex region.

  14. Measurement of ozone and water vapor by Airbus in-service aircraft: The MOZAIC airborne program, An overview

    Science.gov (United States)

    Marenco, Alain; Thouret, ValéRie; NéDéLec, Philippe; Smit, Herman; Helten, Manfred; Kley, Dieter; Karcher, Fernand; Simon, Pascal; Law, Kathy; Pyle, John; Poschmann, Georg; von Wrede, Rainer; Hume, Chris; Cook, Tim

    1998-10-01

    Tentative estimates, using three-dimensional chemistry and transport models, have suggested small ozone increases in the upper troposphere resulting from current aircraft emissions, but have also concluded to significant deficiencies in today's models and to the need to improve them through comparison with extended data sets. The Measurement of Ozone and Water Vapor by Airbus In-Service Aircraft (MOZAIC) program was initiated in 1993 by European scientists, aircraft manufacturers, and airlines to collect experimental data. Its goal is to help understand the atmosphere and how it is changing under the influence of human activity, with particular interest in the effects of aircraft. MOZAIC consists of automatic and regular measurements of ozone and water vapor by five long range passenger airliners flying all over the world. The aim is not to detect direct effects of aircraft emissions on the ozone budget inside the air traffic corridors but to build a large database of measurements to allow studies of chemical and physical processes in the atmosphere, and hence to validate global chemistry transport models. MOZAIC data provide, in particular, detailed ozone and water vapor climatologies at 9-12 km where subsonic aircraft emit most of their exhaust and which is a very critical domain (e.g., radiatively and stratosphere/troposphere exchanges) still imperfectly described in existing models. This will be valuable to improve knowledge about the processes occuring in the upper troposphere and the lowermost stratosphere, and the model treatment of near tropopause chemistry and transport. During MOZAIC I (January 1993-September 1996), fully automatic devices were developed, installed aboard five commercial Airbus A340s, and flown in normal airline service. A second phase, MOZAIC II, started in October 1996 with the aim of continuing the O3 and H2O measurements and doing a feasibility study of new airborne devices (CO, NOy). Between September 1994 and December 1997, 7500

  15. Performance of a Cross-Flow Humidifier with a High Flux Water Vapor Transport Membrane

    Energy Technology Data Exchange (ETDEWEB)

    Ahluwalia, R. K.; Wang, X.; Johnson, W. B.; Berg, F.; Kadylak, D.

    2015-09-30

    Water vapor transport (WVT) flux across a composite membrane that consists of a very thin perfluorosulfonic acid (PFSA) ionomer layer sandwiched between two expanded polytetrafluoroethylene (PTFE) microporous layers is investigated. Static and dynamic tests are conducted to measure WVT flux for different composite structures; a transport model shows that the underlying individual resistances for water diffusion in the gas phase and microporous and ionomer layers and for interfacial kinetics of water uptake at the ionomer surface are equally important under different conditions. A finite-difference model is formulated to determine water transport in a full-scale (2-m2 active membrane area) planar cross-flow humidifier module assembled using pleats of the optimized composite membrane. In agreement with the experimental data, the modeled WVT flux in the module increases at higher inlet relative humidity (RH) of the wet stream and at lower pressures, but the mass transfer effectiveness is higher at higher pressures. The model indicates that the WVT flux is highest under conditions that maintain the wet stream at close to 100% RH while preventing the dry stream from becoming saturated. The overall water transport is determined by the gradient in RH of the wet and dry streams but is also affected by vapor diffusion in the gas layer and the microporous layer.

  16. Observations of water vapor by ground-based micro-wave radiometers and Raman lidar

    Science.gov (United States)

    Han, Yong; Snider, J. B.; Westwater, E. R.; Melfi, S. H.; Ferrare, R. A.

    1994-09-01

    In November to December 1991, a substantial number of remote sensors and in situ instruments were operated together in Coffeyville, Kansas, during the climate experiment FIRE II. Included in the suite of instruments were (1) the NOAA Environmental Technology Laboratory (ETL) three-channel microwave radiometer, (2) the NASA GSFC Raman lidar, (3) ETL radio acoustic sounding system (RASS), and (4) frequent, research-quality radiosondes. The Raman lidar operated only at night and the focus of this portion of the experiment concentrated on clear conditions. The lidar data, together with frequent radiosondes and measurements of temperature profiles (every 15 min) by RASS allowed profiles of temperature and absolute humidity to be estimated every minute. We compared 2-min measurements of brightness temperature (Tb) with calculations of Tb that were based on the Liebe and Lay ton (1987) and Liebe et al. (1993) microwave propagation models, as well as the Waters (1976) model. The comparisons showed the best agreement at 20.6 GHz with the Waters model, with the Liebe et al. (1993) model being best at 31.65 GHz. The results at 90 GHz gave about equal success with the Liebe and Layton (1987) and Liebe et al. (1993) models. Comparisons of precipitable water vapor derived independently from the two instruments also showed excellent agreement, even for averages as short as 2 min. The rms difference between Raman and radiometric determinations of precipitable water vapor was 0.03 cm which is roughly 2%. The experiments clearly demonstrate the potential of simultaneous operation of radiometers and Raman lidars for fundamental physical studies of water vapor.

  17. Formation of microbeads during vapor explosions of Field's metal in water

    KAUST Repository

    Kouraytem, Nadia

    2016-06-17

    We use high-speed video imaging to investigate vapor explosions during the impact of a molten Field\\'s metal drop onto a pool of water. These explosions occur for temperatures above the Leidenfrost temperature and are observed to occur in up to three stages as the metal temperature is increased, with each explosion being more powerful that the preceding one. The Field\\'s metal drop breaks up into numerous microbeads with an exponential size distribution, in contrast to tin droplets where the vapor explosion deforms the metal to form porous solid structures. We compare the characteristic bead size to the wavelength of the fastest growing mode of the Rayleigh-Taylor instability.

  18. Water vapor increase in the northern hemispheric lower stratosphere by the Asian monsoon anticyclone observed during TACTS campaign in 2012

    Science.gov (United States)

    Rolf, Christian; Vogel, Bärbel; Hoor, Peter; Günther, Gebhard; Krämer, Martina; Müller, Rolf; Müller, Stephan; Riese, Martin

    2017-04-01

    Water vapor plays a key role in determining the radiative balance in the upper troposphere and lower stratosphere (UTLS) and thus the climate of the Earth (Forster and Shine, 2002; Riese et al., 2012). Therefore a detailed knowledge about transport pathways and exchange processes between troposphere and stratosphere is required to understand the variability of water vapor in this region. The Asian monsoon anticyclone caused by deep convection over and India and east Asia is able to transport air masses from the troposphere into the nothern extra-tropical stratosphere (Müller et al. 2016, Vogel et al. 2016). These air masses contain pollution but also higher amounts of water vapor. An increase in water vapor of about 0.5 ppmv in the extra-tropical stratosphere above a potential temperature of 380 K was detected between August and September 2012 by in-situ instrumentation above the European northern hemisphere during the HALO aircraft mission TACTS. Here, we investigated the origin of this water vapor increase with the help of the 3D Lagrangian chemistry transport model CLaMS (McKenna et al., 2002). We can assign an origin of the moist air masses in the Asian region (North and South India and East China) with the help of model origin tracers. Additionally, back trajectories of these air masses with enriched water vapor are used to differentiate between transport from the Asia monsoon anticyclone and the upwelling of moister air in the tropics particularly from the Pacific and Southeast Asia.

  19. Cirrus and water vapor transport in the tropical tropopause layer – Part 1: A specific case modeling study

    Directory of Open Access Journals (Sweden)

    T. Dinh

    2012-10-01

    Full Text Available In a simulation of a tropical-tropopause-layer (TTL cirrus forced by a large-scale equatorial Kelvin wave, the radiatively induced mesoscale dynamics of the cloud actively contributes to the transport of water vapor in the vertical direction.

    In a typical TTL cirrus, the heating that results from absorption of radiation by ice crystals induces a mesoscale circulation. Advection of water vapor by the radiatively induced circulation leads to upward advection of the cloudy air. Upward advection of the cloudy air is equivalent to upward transport of water vapor when the air above the cloud is drier than the cloudy air. On the other hand, ice nucleation and depositional growth, followed by sedimentation and sublimation lead to downward transport of water vapor.

    Under the conditions specific to our simulation, the upward transport of water vapor by the mesoscale circulation dominates the downward transport by microphysical processes. The net result is upward transport of water vapor, which is equivalent to hydration of the lower stratosphere. Sensitivity to model conditions and parameters will be discussed in a follow-up paper.

  20. Water vapor isotopes measurements at Mauna Loa, Hawaii: Comparison of laser spectroscopy and remote sensing with traditional methods, and the need for ongoing monitoring

    Science.gov (United States)

    Galewsky, J.; Noone, D.; Sharp, Z.; Worden, J.

    2009-04-01

    The isotopic composition of water vapor (2H/1H and 18O/16 ratios) provides unique information on the transport pathways that link water sources to regional sinks, and thus proves useful in understanding large scale atmospheric humidity budgets. Recent advances in measurement technology allow the monitoring of water vapor isotope composition in ways which has can revolutionize investigations of atmospheric hydrology. Traditional measurement of isotopic composition requires trapping of samples with either large volume vacuum flasks or by trapping liquid samples with cryogens for later analyses using mass spectrometry, and are laborious and seldom span more than just short dedicated observational periods. On the other hand, laser absorption spectroscopy can provide almost continuous and autonomous in situ measurements of isotope abundances with precision almost that of traditional mass spectrometry, and observations from spacecraft can make almost daily maps of the global isotope distributions. In October of 2008 three laser based spectrometers were deployed at the Mauna Loa Laboratory in Hawaii to make continuous measurement of the 2H and 18O abundance of free tropospheric water vapor. These results are compared with traditional measurements and with measurements from two satellite platforms. While providing field validation of the new methodologies, the data show variability which captures the transport processes in the region. The data are used to characterize the role of large scale mixing of dry air, the influence of the boundary layer and the importance of moist convection in controlling the low humidity of subtropical air near Hawaii. Although the record is short, it demonstrates the usefulness of using robust isotope measurements to understand the budgets of the most important greenhouse gas. This work motivates establishing a continuous record of isotopes measurement at baseline sites, like Mauna Loa, such that the changes in water cycle can be understood and