WorldWideScience

Sample records for water based vapour

  1. First detection of tidal behaviour in polar mesospheric water vapour by ground based microwave spectroscopy

    Directory of Open Access Journals (Sweden)

    K. Hallgren

    2012-04-01

    Full Text Available Mesospheric water vapour has been observed above ALOMAR in northern Norway (69° N 16° E by our group since 1995 using a 22 GHz ground based microwave spectrometer. A new instrument with higher sensitivity, providing a much better time resolution especially in the upper mesosphere, was installed in May 2008. The time resolution is high enough to provide observations of daily variations in the water vapour mixing ratio. We present the first ground based detections of tidal behaviour in the polar middle atmospheric water vapour distribution.

    Diurnal and semidiurnal variations of water vapour have been observed and due to the long chemical lifetime of water they are assumed to be caused by changing wind patterns which transport water-rich or poor air into the observed region. The detected tidal behaviour does not follow any single other dynamical field but is instead assumed to be a result of the different wind components.

    Both the diurnal and semidiurnal amplitude and phase components are resolved. The former shows a stable seasonal behaviour consistent with earlier observations of wind fields and model calculations, whereas the latter appears more complex and no regular behaviour has so far been observed.

  2. Microwave measurements of temperature profiles, integrated water vapour, and liquid water path at Thule Air Base, Greenland.

    Science.gov (United States)

    Pace, Giandomenico; Di Iorio, Tatiana; di Sarra, Alcide; Iaccarino, Antonio; Meloni, Daniela; Mevi, Gabriele; Muscari, Giovanni; Cacciani, Marco

    2017-04-01

    A RPG Humidity And Temperature PROfiler (HATPRO-G2 ) radiometer was installed at Thule Air Base (76.5° N, 68.8° W), Greenland, in June 2016 in the framework of the Study of the water VApour in the polar AtmosPhere (SVAAP) project. The Danish Meteorological Institute started measurements of atmospheric properties at Thule Air Base in early '90s. The Thule High Arctic Atmospheric Observatory (THAAO) has grown in size and observing capabilities during the last three decades through the international effort of United States (NCAR and University of Alaska Fairbanks) and Italian (ENEA, INGV, University of Roma and Firenze) institutions (http://www.thuleatmos-it.it). Within this context, the intensive field campaign of the SVAAP project was aimed at the investigation of the surface radiation budget and took place from 5 to 28 July, 2016. After the summer campaign the HATPRO has continued to operate in order to monitor the annual variability of the temperature profile and integrated water vapour as well as the presence and characteristics of liquid clouds in the Artic environment. The combined use of the HATPRO together with other automatic instruments, such as a new microwave spectrometer (the water Vapour Emission Spectrometer for Polar Atmosphere VESPA-22), upward- and downward-looking pyranometers and pyrgeometers, a zenith-looking pyrometer operating in the 9.6-11.5 µm spectral range, an all sky camera, and a meteorological station, allows to investigate the clouds' physical and optical properties, as well as their impact on the surface radiation budget. This study will present and discuss the first few months of HATPRO observations; the effectiveness of the statistical retrieval used to derive the physical parameters from the HATPRO brightness temperatures will also be investigated through the comparison of the temperature and humidity profiles, and integrated water vapour, with data from radiosondes launched during the summer campaign and in winter time.

  3. Water vapour loss measurements on human skin.

    NARCIS (Netherlands)

    Valk, Petrus Gerardus Maria van der

    1984-01-01

    In this thesis, the results of a series of investigations into the barrier function of human skin are presented. In these investigations, the barrier function was assessed by water vapour loss measurements of the skin using a method based on gradient estimation.... Zie: Summary and conclusions

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

    Directory of Open Access Journals (Sweden)

    M. Schneider

    2012-12-01

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

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

    Science.gov (United States)

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

    2012-12-01

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

  6. Intercomparison on measurement of water vapour permeability

    DEFF Research Database (Denmark)

    Hansen, Kurt Kielsgaard

    Three different materials are tested - hard woodfibre board - damp proof course - underlay for roofing The water vapour permeability has been measured according to EN ISO 12572 (2001).......Three different materials are tested - hard woodfibre board - damp proof course - underlay for roofing The water vapour permeability has been measured according to EN ISO 12572 (2001)....

  7. Variability of winter-time middle atmospheric water vapour over the Arctic as observed with a ground-based microwave radiometer

    Science.gov (United States)

    Tschanz, Brigitte; Kivi, Rigel; Rüfenacht, Rolf; Kämpfer, Niklaus

    2014-05-01

    Middle atmospheric water vapour has a long chemical lifetime and can therefore be used as a tracer for dynamics. The ground-based microwave radiometer MIAWARA-C is designed for the use on campaigns and measures profiles of water vapour in the upper stratosphere and mesosphere and thus provides valuable data for the investigation of atmospheric processes. It has been operational for five years and has successfully participated in measurement campaigns under various climatic conditions in Germany, Switzerland, California, Finland and on la Réunion. The temporal resolution of the obtained water vapour profiles approximately 2 hours depending on tropospheric conditions. During two campaigns from January to June 2010 and from July 2011 to April 2013 in Sodankylä, Finland, MIAWARA-C monitored time series of polar middle atmospheric water vapour for three winters with three Sudden Stratospheric Warmings (SSW) occurring in early 2010, 2012 and 2013. The obtained time series are used to study the effects of the three SSWs on middle-atmospheric water vapour. During an SSW, humid mid- to low-latitude air is transported towards the polar region resulting in a fast increase in water vapour. The descent of water vapour after the SSW allows the estimation of the descent rate over the polar region as the normal wintertime circulation reforms. Results from the three SSWs are compared. The ground-based water vapour data is combined with sonde data of the Finnish Meteorological Institute and ground-based microwave wind measurements for one winter in order to obtain a more complete picture of the dynamics in the polar winter atmosphere.

  8. On water vapour transfer inside frozen packs

    National Research Council Canada - National Science Library

    Heiss, R

    1971-01-01

    In the case of various foodstuffs, irreversible water- vapour transporations within the frozen packages can bring about a distinct quality drop caused by damage to the surface of the material as a result of drying out (freezer burn...

  9. Advances in the GNSS Based Estimation of Atmospheric Water Vapour and its Application in Numerical Weather Prediction in Hungary

    Science.gov (United States)

    Juni, I.

    2015-12-01

    In the last decade a CORS network (GNSSnet.hu) has been established in Hungary by FÖMI, incorporating stations from the neighbouring countries as well. The availability of this network enabled us to develop and realize a processing facility to estimate the tropospheric zenith delays from the observations in near real time within the frames of a research project funded by the Hungarian National Research Fund. An automated near-realtime processing facility was established to collect and process the GNSS observations from 54 GNSSnet.hu stations with spatial resolution of approximately 60 kilometres, and it estimates the zenith wet delays (ZWD) and the precipitable water vapour (PW) and validate these values using radiosonde observations. Recently we updated the operational Bernese processing software from version 5.0 to 5.2. The estimation of precipitable water vapour from the zenith wet delays was also further refined and new methods were implemented. The GNSS based zenith total delay and precipitable water vapour estimates are transmitted to EUMETNET's E-GVAP project. Currently the real-time processing of GNSS observations using the PPP technique is experimented to enable the exploitation of GNSS observations for nowcasting applications. The first results and comparisons with the near-realtime estimations are presented on this poster. We contribute to a dedicated project, concentrating around the Transcarpathian region, which targets the real-time monitoring of severe weather events based on GNSS analysis. The first results may expected by the end of this year. The Hungarian Meteorological Service has also conducted the first tests of the zenith total delay assimilation in their AROME numerical weather prediction model. The data assimilation diagnostics showed that the zenit total delays originated from nearly 70 stations have important contribution to AROME analysis (especially to humidity analysis). The verification results of the first test conducted in January

  10. estimation of precipitable water vapour in nigeria using surface ...

    African Journals Online (AJOL)

    USER

    affects the climate and weather systems through its effect on the atmospheric temperature and energy transport (Garrison, 1992; Follette et al.,. 2008). A very important measure of the atmospheric water vapour is the precipitable water vapour. (PWV). Precipitable Water Vapour (PWV) is a measure of the total amount of water ...

  11. Upper tropospheric water vapour variability over tropical latitudes ...

    Indian Academy of Sciences (India)

    Upper tropospheric water vapour variability over tropical latitudes observed using radiosonde and satellite measurements. Ghouse Basha ... Keywords. Water vapour; radiosonde; satellite measurements. ... National Atmospheric Research Laboratory (NARL), Department of Space, Government of India, Gadanki, PB No. 123 ...

  12. Intercomparison of TCCON and MUSICA Water Vapour Products

    Science.gov (United States)

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

    2014-12-01

    We present an intercomparison between the water vapour products from the Total Carbon Column Observing Network (TCCON) and the MUlti-platform remote Sensing of Isotopologues for investigating the Cycle of Atmospheric water (MUSICA), two datasets from ground-based Fourier Transform InfraRed (FTIR) spectrometers with good global representation. Where possible, comparisons to radiosondes are also included. The near-infrared TCCON measurements are optimized to provide precise monitoring of greenhouse gases for carbon cycle studies; however, TCCON's retrievals also produce water vapour products. The mid-infrared MUSICA products result from retrievals optimized to give precise and accurate information about H2O, HDO, and δD. The MUSICA water vapour products have been validated by extensive intercomparisons with H2O and δD in-situ measurements made from ground, radiosonde, and aircraft (Schneider et al. 2012, 2014), as well as by intercomparisons with satellite-based H2O and δD remote sensing measurements (Wiegele et al., 2014). This dataset provides a valuable reference point for other measurements of water vapour. This study is motivated by the limited intercomparisons performed for TCCON water vapour products and limited characterisation of their uncertainties. We compare MUSICA and TCCON products to assess the potential for TCCON measurements to contribute to studies of the water cycle, water vapour's role in climate and use as a tracer for atmospheric dynamics, and to evaluate the performance of climate models. The TCCON and MUSICA products result from measurements taken using the same FTIR instruments, enabling a comparison with constant instrumentation. The retrieval techniques differ, however, in their method and a priori information. We assess the impact of these differences and characterize the comparability of the TCCON and MUSICA datasets.

  13. Condensation of water vapour on moss-dominated biological soil ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Earth System Science; Volume 123; Issue 2 ... Condensation; water vapour; desert ecosystem; moss; biological soil crust. Abstract. Characteristics of water vapour condensation, including the onset, duration, and amount of water vapour condensation on moss-dominated biological soil crust ...

  14. Water vapour measurements during POLINAT 1

    Energy Technology Data Exchange (ETDEWEB)

    Ovarlez, J.; Ovarlez, H. [Centre National de la Recherche Scientifique, 91 - Palaiseau (France). Lab. de Meteorologie Dynamique

    1997-12-31

    The POLINAT (POLlution from aircraft emissions In the North ATlantic flight corridor)1 experiment has been performed within the framework of the Environment Programme of the Commission of the European Community. It was devoted to the study of the pollution from aircraft in the North Atlantic flight corridor, in order to investigate the impact of pollutants emitted by aircraft on the concentrations of ozone and other trace gases in the upper troposphere and lower stratosphere. For that experiment the water vapour content was measured with a frost-point hygrometer on board of the DLR Falcon research aircraft. This instrument is described, and some selected results are given. (author) 19 refs.

  15. Variability of water vapour in the Arctic stratosphere

    Science.gov (United States)

    Thölix, Laura; Backman, Leif; Kivi, Rigel; Karpechko, Alexey Yu.

    2016-04-01

    This study evaluates the stratospheric water vapour distribution and variability in the Arctic. A FinROSE chemistry transport model simulation covering the years 1990-2014 is compared to observations (satellite and frost point hygrometer soundings), and the sources of stratospheric water vapour are studied. In the simulations, the Arctic water vapour shows decadal variability with a magnitude of 0.8 ppm. Both observations and the simulations show an increase in the water vapour concentration in the Arctic stratosphere after the year 2006, but around 2012 the concentration started to decrease. Model calculations suggest that this increase in water vapour is mostly explained by transport-related processes, while the photochemically produced water vapour plays a relatively smaller role. The increase in water vapour in the presence of the low winter temperatures in the Arctic stratosphere led to more frequent occurrence of ice polar stratospheric clouds (PSCs) in the Arctic vortex. We perform a case study of ice PSC formation focusing on January 2010 when the polar vortex was unusually cold and allowed large-scale formation of PSCs. At the same time a large-scale persistent dehydration was observed. Ice PSCs and dehydration observed at Sodankylä with accurate water vapour soundings in January and February 2010 during the LAPBIAT (Lapland Atmosphere-Biosphere facility) atmospheric measurement campaign were well reproduced by the model. In particular, both the observed and simulated decrease in water vapour in the dehydration layer was up to 1.5 ppm.

  16. Measuring variations of δ18O and δ2H in atmospheric water vapour using two commercial laser-based spectrometers: an instrument characterisation study

    Directory of Open Access Journals (Sweden)

    S. Pfahl

    2012-07-01

    Full Text Available Variations of stable water isotopes in water vapour have become measurable at a measurement frequency of about 1 Hz in recent years using novel laser spectroscopic techniques. This enables us to perform continuous measurements for process-based investigations of the atmospheric water cycle at the time scales relevant for synoptic and mesoscale meteorology. An important prerequisite for the interpretation of data from automated field measurements lasting for several weeks or months is a detailed knowledge about instrument properties and the sources of measurement uncertainty. We present here a comprehensive characterisation and comparison study of two commercial laser spectroscopic systems based on cavity ring-down spectroscopy (Picarro and off-axis integrated cavity output spectroscopy (Los Gatos Research. The uncertainty components of the measurements were first assessed in laboratory experiments, focussing on the effects of (i water vapour mixing ratio, (ii measurement stability, (iii uncertainties due to calibration and (iv response times of the isotope measurements due to adsorption-desorption processes on the tubing and measurement cavity walls. Based on the experience from our laboratory experiments, we set up a one-week field campaign for comparing measurements of the ambient isotope signals from the two laser spectroscopic systems. The optimal calibration strategy determined for both instruments was applied as well as the correction functions for water vapour mixing ratio effects. The root mean square difference between the isotope signals from the two instruments during the field deployment was 2.3‰ for δ2H, 0.5‰ for δ18O and 3.1‰ for deuterium excess. These uncertainty estimates from field measurements compare well to those found in the laboratory experiments. The present quality of measurements from laser spectroscopic instruments combined with a calibration system opens new possibilities for investigating the atmospheric

  17. Water vapour variability and trends in the Arctic stratosphere

    Science.gov (United States)

    Thölix, Laura; Kivi, Rigel; Backman, Leif; Karpechko, Alexey

    2014-05-01

    Water vapour in the upper troposphere-lower stratosphere (UTLS) is a radiatively and chemically important trace gas. Stratospheric water vapour also affects ozone chemistry through odd-hydrogen chemistry and formation of polar stratospheric clouds (PSC). Both transport and chemistry contribute to the extratropical lower stratospheric water vapour distribution and trends. The main sources of stratospheric water vapour are intrusion through the tropical tropopause and production from oxidation of methane. Accurate observations of UTLS water vapour are difficult to obtain due to the strong gradient in the water vapour profile over the tropopause. However, modelling the stratospheric water vapour distribution is challenging and accurate measurements are needed for model validation. Trends in Arctic water vapour will be analysed and explained in terms of contribution from different processes (transport and chemistry), using observations and chemistry transport model (CTM) simulations. Accurate water vapour soundings from Sodankylä will be used to study water vapour within the Arctic polar vortex, including process studies on formation of PSCs and dehydration. Water vapour profiles measured during the LAPBIAT atmospheric sounding campaign in Sodankylä in January 2010 indicated formation of ice clouds and dehydration. Effects on ozone chemistry will also be studied. Global middle atmospheric simulations have been performed with the FinROSE-ctm using ERA-Interim winds and temperatures. The FinROSE-ctm is a global middle atmosphere model that produces the distribution of 30 long-lived species and tracers and 14 short-lived species. The chemistry describes around 110 gas phase reactions, 37 photodissociation processes and the main heterogeneous reactions related to aerosols and polar stratospheric clouds.

  18. Low pressure water vapour plasma treatment of surfaces for biomolecules decontamination

    DEFF Research Database (Denmark)

    Fumagalli, F; Kylian, O; Amato, Letizia

    2012-01-01

    Decontamination treatments of surfaces are performed on bacterial spores, albumin and brain homogenate used as models of biological contaminations in a low-pressure, inductively coupled plasma reactor operated with water-vapour-based gas mixtures. It is shown that removal of contamination can...... vapour plasma process are discussed for practical applications in medical devices decontamination....

  19. The CM SAF SSM/I-based total column water vapour climate data record: methods and evaluation against re-analyses and satellite

    Directory of Open Access Journals (Sweden)

    M. Schröder

    2013-03-01

    Full Text Available The European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT Satellite Application Facility on Climate Monitoring (CM SAF aims at the provision and sound validation of well documented Climate Data Records (CDRs in sustained and operational environments. In this study, a total column water vapour path (WVPA climatology from CM SAF is presented and inter-compared to water vapour data records from various data sources. Based on homogenised brightness temperatures from the Special Sensor Microwave Imager (SSM/I, a climatology of WVPA has been generated within the Hamburg Ocean–Atmosphere Fluxes and Parameters from Satellite (HOAPS framework. Within a research and operation transition activity the HOAPS data and operation capabilities have been successfully transferred to the CM SAF where the complete HOAPS data and processing schemes are hosted in an operational environment. An objective analysis for interpolation, namely kriging, has been applied to the swath-based WVPA retrievals from the HOAPS data set. The resulting climatology consists of daily and monthly mean fields of WVPA over the global ice-free ocean. The temporal coverage ranges from July 1987 to August 2006. After a comparison to the precursor product the CM SAF SSM/I-based climatology has been comprehensively compared to different types of meteorological analyses from the European Centre for Medium-Range Weather Forecasts (ECMWF-ERA40, ERA INTERIM and operational analyses and from the Japan Meteorological Agency (JMA–JRA. This inter-comparison shows an overall good agreement between the climatology and the analyses, with daily absolute biases generally smaller than 2 kg m−2. The absolute value of the bias to JRA and ERA INTERIM is typically smaller than 0.5 kg m−2. For the period 1991–2006, the root mean square error (RMSE for both reanalyses is approximately 2 kg m−2. As SSM/I WVPA and radiances are assimilated into JMA and all ECMWF analyses and

  20. Retrieving mesospheric water vapour from observations of volume scattering radiances

    Directory of Open Access Journals (Sweden)

    P. Vergados

    2009-02-01

    Full Text Available This study examines the possibility for a theoretical approach in the estimation of water vapour mixing ratios in the vicinity of polar mesospheric clouds (PMC using satellite observations of Volume Scattering Radiances (VSR obtained at the wavelength of 553 nm. The PMC scattering properties perturb the underlying molecular Rayleigh scattered solar radiance of the background atmosphere. As a result, the presence of PMC leads to an enhancement in the observed VSR at the altitude of the layer; the PMC VSRs are superimposed on the exponentially decreasing with height Rayleigh VSR, of the PMC-free atmosphere. The ratio between the observed and the Rayleigh VSR of the background atmosphere is used to simulate the environment in which the cloud layer is formed. In addition, a microphysical model of ice particle formation is employed to predict the PMC VSRs. The initial water vapour profile is perturbed until the modelled VSRs match the observed, at which point the corresponding temperature and water vapour profiles can be considered as a first approximation of those describing the atmosphere at the time of the observations. The role of temperature and water vapour in the cloud formation is examined by a number of sensitivity tests suggesting that the water vapour plays a dominant role in the cloud formation in agreement with experimental results. The estimated water vapour profiles are compared with independent observations to examine the model capability in the context of this study. The results obtained are in a good agreement at the peak of the PMC layer although the radiance rapidly decreases with height below the peak. This simplified scenario indicates that the technique employed can give a first approximation estimate of the water vapour mixing ratio, giving rise to the VSR observed in the presence of PMC.

  1. Validation of water vapour profiles (version 13 retrieved by the IMK/IAA scientific retrieval processor based on full resolution spectra measured by MIPAS on board Envisat

    Directory of Open Access Journals (Sweden)

    M. Milz

    2009-07-01

    Full Text Available Vertical profiles of stratospheric water vapour measured by the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS with the full resolution mode between September 2002 and March 2004 and retrieved with the IMK/IAA scientific retrieval processor were compared to a number of independent measurements in order to estimate the bias and to validate the existing precision estimates of the MIPAS data. The estimated precision for MIPAS is 5 to 10% in the stratosphere, depending on altitude, latitude, and season. The independent instruments were: the Halogen Occultation Experiment (HALOE, the Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS, the Improved Limb Atmospheric Spectrometer-II (ILAS-II, the Polar Ozone and Aerosol Measurement (POAM III instrument, the Middle Atmospheric Water Vapour Radiometer (MIAWARA, the Michelson Interferometer for Passive Atmospheric Sounding, balloon-borne version (MIPAS-B, the Airborne Microwave Stratospheric Observing System (AMSOS, the Fluorescent Stratospheric Hygrometer for Balloon (FLASH-B, the NOAA frostpoint hygrometer, and the Fast In Situ Hygrometer (FISH. For the in-situ measurements and the ground based, air- and balloon borne remote sensing instruments, the measurements are restricted to central and northern Europe. The comparisons to satellite-borne instruments are predominantly at mid- to high latitudes on both hemispheres. In the stratosphere there is no clear indication of a bias in MIPAS data, because the independent measurements in some cases are drier and in some cases are moister than the MIPAS measurements. Compared to the infrared measurements of MIPAS, measurements in the ultraviolet and visible have a tendency to be high, whereas microwave measurements have a tendency to be low. The results of χ2-based precision validation are somewhat controversial among the comparison estimates. However, for comparison instruments whose error budget also includes

  2. Kinetic model of water vapour adsorption by gluten-free starch

    Science.gov (United States)

    Ocieczek, Aneta; Kostek, Robert; Ruszkowska, Millena

    2015-01-01

    This study evaluated the kinetics of water vapour adsorption on the surface of starch molecules derived from wheat. The aim of the study was to determine an equation that would allow estimation of water content in tested material in any timepoint of the adsorption process aimed at settling a balance with the environment. An adsorption isotherm of water vapour on starch granules was drawn. The parameters of the Guggenheim, Anderson, and De Boer equation were determined by characterizing the tested product and adsorption process. The equation of kinetics of water vapour adsorption on the surface of starch was determined based on the Guggenheim, Anderson, and De Boer model describing the state of equilibrium and on the model of a first-order linear inert element describing the changes in water content over time.

  3. Analysis of radiosonde data on tropospheric water vapour in Nigeria ...

    African Journals Online (AJOL)

    The analyses of some atmospheric water vapour parameters derived from radiosonde data at the three existing radiosonde stations in Nigeria are reported. The stations essentially represent the climates of the southern (coastal), middlebelt (savannah), and northern (sub-sahel) regions of the country. Monthly means of the ...

  4. Upper tropospheric water vapour variability over tropical latitudes ...

    Indian Academy of Sciences (India)

    Upper tropospheric water vapour variability over tropical latitudes observed using radiosonde and satellite measurements. Ghouse Basha1, M Venkat Ratnam1,∗ and B V Krishna Murthy2. 1National Atmospheric Research Laboratory (NARL), Department of Space, Government of India,. Gadanki, PB No. 123, Tirupati 517 ...

  5. Carbon dioxide and water vapour characteristics on the west coast ...

    Indian Academy of Sciences (India)

    Carbon dioxide and water vapour in the atmo- sphere are considered as the green-house gases and responsible for the global warming, hence much attention has been given to its measurement and analysis (Jones et al. 1978; Jones and Smith 1977;. Leuning et al. 1982; Ohtaki and Matsui 1982;. Ohtaki 1985).

  6. Variation In Surface Water Vapour Density Over Four Nigerian Stations

    African Journals Online (AJOL)

    The surface water vapour density ρ has been studied using monthly averages of temperature and relative humidity at four selected weather stations in Nigeria for the years 1987 to 1991. It is found that during the dry season months of November to March, ρ is higher at night by an average of about 9.9% than during the day ...

  7. Effect of preparation procedures on catalytic activity and selectivity of copper-based mixed oxides in selective catalytic oxidation of ammonia into nitrogen and water vapour

    Science.gov (United States)

    Jabłońska, Magdalena; Nocuń, Marek; Gołąbek, Kinga; Palkovits, Regina

    2017-11-01

    The selective oxidation of ammonia into nitrogen and water vapour (NH3-SCO) was studied over Cu-Mg(Zn)-Al-(Zr) mixed metal oxides, obtained by coprecipitation and their subsequent calcination. The effect of acid-base properties of Cu-Mg-Al-Ox on catalytic activity was investigated by changing the Mg/Al molar ratio. Other Cu-containing oxides were prepared by rehydration of calcined Mg-Al hydrotalcite-like compounds or thermal decomposition of metal nitrate precursors. XRD, BET, NH3-TPD, H2-TPR, XPS, FTIR with adsorption of pyridine and CO as well as TEM techniques were used for catalysts characterization. The results of catalytic tests revealed a crucial role of easily reducible highly dispersed copper oxide species to obtain enhanced activity and N2 selectivity in NH3-SCO. The selective catalytic reduction of NO by NH3 (NH3-SCR) and in situ DRIFT of NH3 sorption indicated that NH3-SCO proceeds according to the internal selective catalytic reduction mechanism (i-SCR).

  8. Leidenfrost vapour layer moderation of the drag crisis and trajectories of superhydrophobic and hydrophilic spheres falling in water

    KAUST Repository

    Vakarelski, Ivan Uriev

    2014-01-01

    We investigate the dynamic effects of a Leidenfrost vapour layer sustained on the surface of heated steel spheres during free fall in water. We find that a stable vapour layer sustained on the textured superhydrophobic surface of spheres falling through 95 °C water can reduce the hydrodynamic drag by up to 75% and stabilize the sphere trajectory for the Reynolds number between 104 and 106, spanning the drag crisis in the absence of the vapour layer. For hydrophilic spheres under the same conditions, the transition to drag reduction and trajectory stability occurs abruptly at a temperature different from the static Leidenfrost point. The observed drag reduction effects are attributed to the disruption of the viscous boundary layer by the vapour layer whose thickness depends on the water temperature. Both the drag reduction and the trajectory stabilization effects are expected to have significant implications for development of sustainable vapour layer based technologies. © the Partner Organisations 2014.

  9. Leidenfrost vapour layer moderation of the drag crisis and trajectories of superhydrophobic and hydrophilic spheres falling in water.

    Science.gov (United States)

    Vakarelski, Ivan U; Chan, Derek Y C; Thoroddsen, Sigurdur T

    2014-08-21

    We investigate the dynamic effects of a Leidenfrost vapour layer sustained on the surface of heated steel spheres during free fall in water. We find that a stable vapour layer sustained on the textured superhydrophobic surface of spheres falling through 95 °C water can reduce the hydrodynamic drag by up to 75% and stabilize the sphere trajectory for the Reynolds number between 10(4) and 10(6), spanning the drag crisis in the absence of the vapour layer. For hydrophilic spheres under the same conditions, the transition to drag reduction and trajectory stability occurs abruptly at a temperature different from the static Leidenfrost point. The observed drag reduction effects are attributed to the disruption of the viscous boundary layer by the vapour layer whose thickness depends on the water temperature. Both the drag reduction and the trajectory stabilization effects are expected to have significant implications for development of sustainable vapour layer based technologies.

  10. Modelling and interpreting the isotopic composition of water vapour in convective updrafts

    Directory of Open Access Journals (Sweden)

    M. Bolot

    2013-08-01

    Full Text Available The isotopic compositions of water vapour and its condensates have long been used as tracers of the global hydrological cycle, but may also be useful for understanding processes within individual convective clouds. We review here the representation of processes that alter water isotopic compositions during processing of air in convective updrafts and present a unified model for water vapour isotopic evolution within undiluted deep convective cores, with a special focus on the out-of-equilibrium conditions of mixed-phase zones where metastable liquid water and ice coexist. We use our model to show that a combination of water isotopologue measurements can constrain critical convective parameters, including degree of supersaturation, supercooled water content and glaciation temperature. Important isotopic processes in updrafts include kinetic effects that are a consequence of diffusive growth or decay of cloud particles within a supersaturated or subsaturated environment; isotopic re-equilibration between vapour and supercooled droplets, which buffers isotopic distillation; and differing mechanisms of glaciation (droplet freezing vs. the Wegener–Bergeron–Findeisen process. As all of these processes are related to updraft strength, particle size distribution and the retention of supercooled water, isotopic measurements can serve as a probe of in-cloud conditions of importance to convective processes. We study the sensitivity of the profile of water vapour isotopic composition to differing model assumptions and show how measurements of isotopic composition at cloud base and cloud top alone may be sufficient to retrieve key cloud parameters.

  11. Influence of collisional rate coefficients on water vapour excitation

    Science.gov (United States)

    Daniel, F.; Goicoechea, J. R.; Cernicharo, J.; Dubernet, M.-L.; Faure, A.

    2012-11-01

    Context. Water is a key molecule in many astrophysical studies that deal with star or planet forming regions, evolved stars, and galaxies. Its high dipole moment makes this molecule subthermally populated under the typical conditions of most astrophysical objects. This motivated calculation of various sets of collisional rate coefficients (CRC) for H2O (with He or H2), which are needed to model its rotational excitation and line emission. Aims: The most accurate set of CRC are the quantum rates that involve H2. However, they have been published only recently, and less accurate CRC (quantum with He or quantum classical trajectory (QCT) with H2) were used in many studies before that. This work aims to underline the impact that the new available set of CRC have on interpretations of water vapour observations. Methods: We performed accurate non-local, non-LTE radiative transfer calculations using different sets of CRC to predict the line intensities from transitions that involve the lowest energy levels of H2O (E find that the intensities based on the quantum and QCT CRC are in good agreement. However, at relatively low H2 volume density (n(H2) find differences in the predicted line intensities of up to a factor of ~3 for the bulk of the lines. Most of the recent studies interpreting early Herschel Space Observatory spectra have used the QCT CRC. Our results show that, although the global conclusions from those studies will not be drastically changed, each case has to be considered individually, since depending on the physical conditions, the use of the QCT CRC may lead to a mis-estimate of the water vapour abundance of up to a factor of ~3. Additionally, the comparison of the quantum state-to-state and thermalised CRC, including the description of the population of the H2 rotational levels, show that above TK ~ 100 K, large differences are expected from those two sets for the p-H2 symmetry. Finally, we find that at low temperature (i.e. TK < 100 K) modelled line

  12. 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 ...

  13. GPS sensing of precipitable water vapour during the March 2010 Melbourne storm

    Science.gov (United States)

    Choy, S.; Wang, C.; Zhang, K.; Kuleshov, Y.

    2013-11-01

    The March 2010 Melbourne storm is used as a case study to examine the potential of using Global Positioning System (GPS) observations for studying the precipitable water vapour (PWV) field. The Victorian statewide GPS infrastructure network, i.e. GPSnet, was used in this study. GPSnet is currently the only statewide and densest GPS infrastructure network in Australia, which provides an excellent opportunity to examine the distribution of water vapour as the severe weather system passed over the state. Data from 15 GPSnet stations were processed over a one-week period, i.e. a few days prior to and after the storm passage, during which the course of the storm extended from the west to the southeast corner of the state. In addition, data from two radiosonde sites of the Australian Bureau of Meteorology Upper Air Network were used to compare and validate the GPS derived PWV measurements. The findings demonstrate that there is strong spatial and temporal correlation between variations of the ground-based GPS-PWV estimates and the passage of the storm over the state. This is encouraging as the ground-based GPS water vapour sensing technique can be considered as a supplemental meteorological sensor in studying severe weather events. The advantage of using ground-based GPS-PWV technique is that it is capable of providing continuous observation of the storm passage with high temporal resolution. The spatial resolution of the distribution of water vapour is dependent on the geographical location and density of the GPS stations.

  14. On the representativity of water vapour measurements at Boulder for global stratospheric trends

    Science.gov (United States)

    Lossow, S.

    2016-12-01

    Long-term changes of water vapour in the lower stratosphere inevitably affect the surface climate. Thus understanding such changes is of primary importance. The longest continuous data set is based on balloon-borne frost point hygrometer observations at Boulder. Overall this data set shows an increase in water vapour since the 1980s accompanied by large variability on short time scales (Hurst et al., 2011). Recently a merged satellite data set, covering the time period between 1988 and 2010, has been analysed showing a decrease of water vapour in the lower stratosphere (Hegglin et al., 2014). This discrepancy is difficult to reconcile. There might be problems with one data set or even with both. Also the local behaviour at Boulder might not be representative for the zonal mean behaviour, which is represented by the satellite observations. So far this has been assumed and the Boulder changes have even been considered to be globally representative. Here I present investigations of this aspect using both model simulations and observations. References: Hegglin et al. (2014), "Vertical structure of stratospheric water vapour trends derived from merged satellite data", Nature Geoscience, 7, 768 - 776, doi:10.1038/ngeo2236. Hurst et al. (2011), "Stratospheric water vapor trends over Boulder, Colorado: Analysis of the 30 year Boulder record", Journal of Geophysical Research, 116, D02,306, doi:10.1029/2010JD015065.

  15. Technical note: Water vapour concentration and flux measurements with PTR-MS

    Directory of Open Access Journals (Sweden)

    C. Ammann

    2006-01-01

    Full Text Available The most direct approach for measuring the exchange of biogenic volatile organic compounds between terrestrial ecosystems and the atmosphere is the eddy covariance technique. It has been applied several times in the last few years using fast response proton-transfer-reaction mass spectrometry (PTR-MS. We present an independent validation of this technique by applying it to measure the water vapour flux in comparison to a common reference system comprising an infra-red gas analyser (IRGA. Water vapour was detected in the PTR-MS at mass 37 (atomic mass units corresponding to the cluster ion H3O+·H2O. During a five-week field campaign at a grassland site, we obtained a non-linear but stable calibration function between the mass 37 signal and the reference water vapour concentration. With a correction of the high-frequency damping loss based on empirical ogive analysis, the eddy covariance water vapour flux obtained with the PTR-MS showed a very good agreement with the flux of the reference system. The application of the empirical ogive method for high-frequency correction led to significantly better results than using a correction based on theoretical spectral transfer functions. This finding is attributed to adsorption effects on the tube walls that are presently not included in the theoretical correction approach. The proposed high-frequency correction method can also be used for other trace gases with different adsorption characteristics.

  16. Water vapour loss threshold and induction of cholinergic urticaria.

    Science.gov (United States)

    Tupker, R A; Doeglas, H M

    1990-01-01

    A patient is described with cholinergic urticaria (CU) in whom the symptoms could be provoked by gustatory stimuli. The aim of this study was to investigate whether there is a threshold of sweating (monitored by skin water vapour loss (SVL) measurements) at which CU can be provoked. Provocations with lemon and sal-ammoniac liquorice induced transient sweating differing both in degree and duration. Only 'doubly salted' liquorice, which caused the most intense sweat response, resulted in urticarial lesions. This findings suggest a threshold dependency for the induction of CU. SVL measurement may be a useful method for the evaluation of sweating tests in CU patients.

  17. The Seasonal Cycle of Water Vapour on Mars from Assimilation of Thermal Emission Spectrometer Data

    Science.gov (United States)

    Steele, Liam J.; Lewis, Stephen R.; Patel, Manish R.; Montmessin, Franck; Forget, Francois; Smith, Michael D.

    2014-01-01

    We present for the first time an assimilation of Thermal Emission Spectrometer (TES) water vapour column data into a Mars global climate model (MGCM). We discuss the seasonal cycle of water vapour, the processes responsible for the observed water vapour distribution, and the cross-hemispheric water transport. The assimilation scheme is shown to be robust in producing consistent reanalyses, and the global water vapour column error is reduced to around 2-4 pr micron depending on season. Wave activity is shown to play an important role in the water vapour distribution, with topographically steered flows around the Hellas and Argyre basins acting to increase transport in these regions in all seasons. At high northern latitudes, zonal wavenumber 1 and 2 stationary waves during northern summer are responsible for spreading the sublimed water vapour away from the pole. Transport by the zonal wavenumber 2 waves occurs primarily to the west of Tharsis and Arabia Terra and, combined with the effects of western boundary currents, this leads to peak water vapour column abundances here as observed by numerous spacecraft. A net transport of water to the northern hemisphere over the course of one Mars year is calculated, primarily because of the large northwards flux of water vapour which occurs during the local dust storm around L(sub S) = 240-260deg. Finally, outlying frost deposits that surround the north polar cap are shown to be important in creating the peak water vapour column abundances observed during northern summer.

  18. A miniature discriminating monitor for tritiated water vapour

    Energy Technology Data Exchange (ETDEWEB)

    Edwards, R.A.H.; Ravazzani, A.; Pacenti, P. [European Commission, JRC, Institute for Advanced Material, Ispra, Vatican City State, Holy See (Italy); Campi, F. [Nuclear Engineering Dept., Polytechnic of Milan (Italy)

    1998-07-01

    In detecting tritium in air (or other gas) for worker safety, it is important to discriminate between tritiated water vapour and elemental tritium, because the first is much more easily absorbed in the lungs. We haveinvented (patent pending) an innovative discriminating monitor which works better than existing designs, and is much smaller. The air (or other sample gas) passes over a large surface area of solid scintillator, which is surface-treated to make it hygroscopic. Tritiated water vapour in the air exchanges continuously, rapidly and reversibly with the water in the thin hygroscopic layer; which is of the order of 1 micron thick. The beta-emissions from tritium in the hygroscopic layer hit the solid scintillator, causing flashes of light that are detected by a photomultiplier. The new discriminating monitor for tritiated species in air offers superior performance to existing discriminating monitors, and is much smaller. It is planned to develop a portable version which could serve as a personal tritium monitor. (authors)

  19. Study of water vapour adsorption kinetics on aluminium oxide materials

    Science.gov (United States)

    Livanova, Alesya; Meshcheryakov, Evgeniy; Reshetnikov, Sergey; Kurzina, Irina

    2017-11-01

    Adsorbents on the basis of active aluminum oxide are still of demand on the adsorbent-driers market. Despite comprehensive research of alumina adsorbents, and currently is an urgent task to improve their various characteristics, and especially the task of increasing the sorption capacity. In the present work kinetics of the processes of water vapours' adsorption at room temperature on the surface of desiccant samples has been studied. It was obtained on the basis of bayerite and pseudoboehmite experimentally. The samples of pseudoboehmite modified with sodium and potassium ions were taken as study objects. The influence of an adsorbent's grain size on the kinetics of water vapours' adsorption was studied. The 0.125-0.25 mm and 0.5-1.0 mm fractions of this sample were used. It has been revealed that the saturation water vapor fine powder (0.125-0.25 mm) is almost twofold faster in comparison with the sample of fraction 0.5-1.0 mm due to the decrease in diffusion resistance in the pores of the samples when moving from the sample of larger fraction to the fine-dispersed sample. It has been established that the adsorption capacity of the pseudoboehmite samples, modified by alkaline ions, is higher by ˜40 %, than for the original samples on the basis of bayerite and pseudoboehmite.

  20. Thermally decarboxylated sodium bicarbonate: Interactions with water vapour, calorimetric study

    Directory of Open Access Journals (Sweden)

    Natalia Volkova

    2013-06-01

    Full Text Available Isothermal titration calorimetry (ITC was used to study interactions between water vapour and the surface of thermally converted sodium bicarbonate (NaHCO3. The decarboxylation degree of the samples was varied from 3% to 35% and the humidity range was 54–100%. The obtained enthalpy values were all exothermic and showed a positive linear correlation with decarboxylation degrees for each humidity studied. The critical humidity, 75% (RHo, was determined as the inflection point on a plot of the mean−ΔHkJ/mole Na2CO3 against RH. Humidities above the critical humidity lead to complete surface dissolution. The water uptake (m was determined after each calorimetric experiment, complementing the enthalpy data. A mechanism of water vapour interaction with decarboxylated samples, including the formation of trona and Wegscheider’s salt on the bicarbonate surface is proposed for humidities below RHo. Keywords: Isothermal titration calorimetry, Sodium bicarbonate, Sodium carbonate, Trona salt, Wegscheider’s salt, Enthalpy, Relative humidity, Pyrolytic decarboxylation

  1. One year observation of water vapour isotopic composition at Ivittuut, Southern Greenland

    Science.gov (United States)

    Bonne, Jean-Louis; Masson-Delmotte, Valérie; Delmotte, Marc; Cattani, Olivier; Sodemann, Harald; Risi, Camille

    2013-04-01

    In September 2011, an automatic continuous water vapour isotopic composition monitoring instrument has been installed in the atmospheric station of Ivittuut (61.21° N, 48.17° W), southern Greenland. Precipitation has been regularly sampled on site at event to weekly scales and analysed in our laboratory for isotopic composition. Meteorological parameters (temperature, pressure, relative humidity, wind speed and direction) and atmospheric composition (CO2, CH4, Atmospheric Potential Oxygen) are also continuously monitored at Ivittuut. The meteorological context of our observation period will be assessed by comparison with the local climatology. The water vapour analyser is a Picarro Wavelength Scanned Cavity Ring-Down Spectrometer (WS-CRDS, model L2120i). It is automatically and regularly calibrated on the VSMOW scale using measurements of the isotopic composition of vaporized reference water standards using the Picarro Syringe Delivery Module (SDM). As measurements are sensitive to humidity level, an experimentally estimated calibration response function is used to correct our isotopic measurements. After data treatment, successive isotopic measurements of reference waters have a standard deviation of around 0.35 per mil for δ18O and 2.3 per mil for δD. Our instrumentation protocol and data quality control method will be presented, together with our one year δ18O, δD and d-excess measurements in water vapour and precipitation. The relationship between surface water vapour isotopic composition and precipitation isotopic composition will be investigated based on a distillation model. Specific difficulties linked to our low maintenance remote station will also be discussed. The processes responsible for the synoptic variability of Ivittuut water vapour isotopic composition will be investigated by comparing our observational dataset with (i) atmospheric back-trajectories and (ii) results from an isotopically-enabled atmospheric general circulation model (AGCM

  2. Utility of DMSP-SSM/I for integrated water vapour over the Indian seas

    Indian Academy of Sciences (India)

    Recent algorithms for Special Sensor Microwave/Imager (DMSP-SSM/I) satellite data are used for estimating integrated water vapour over the Indian seas. ... On the basis of this algorithm, distribution of integrated water vapour is determined during the monsoon depression (22nd{27th July, 1992) that formed over the Bay of ...

  3. Utility of DMSP-SSM/I for integrated water vapour over the Indian seas

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging Solutions)

    Recent algorithms for Special Sensor Microwave/Imager (DMSP-SSM/I) satellite data are used for estimating integrated water vapour over the Indian seas. Integrated water vapour obtained from these algorithms is compared with that derived from radiosonde observations at Minicoy and Port. Blair islands. Algorithm-3 of ...

  4. Prediction of clay content from water vapour sorption isotherms considering hysteresis and soil organic matter content

    DEFF Research Database (Denmark)

    Arthur, E.; Tuller, M.; Møldrup, Per

    2015-01-01

    Soil texture, in particular the clay fraction, governs numerous environmental, agricultural and engineering soil processes. Traditional measurement methods for clay content are laborious and impractical for large-scale soil surveys. Consequently, clay prediction models that are based on water...... for estimating clay content from hygroscopic water at different relative humidity (RH) levels while considering hysteresis and organic matter content. Continuous adsorption/desorption vapour sorption isotherm loops were measured for 150 differently textured soils with a state-of-the-art vapour sorption analyser...... within a RH range from 3 to 93%. The clay contents, which ranged between 1 and 56%, were measured with a combination of sieving and sedimentation methods. Two regression models were developed for both adsorption and desorption at 10 RH levels (5, 10, 20, 30, 40, 50, 60, 70, 80 and 90%). While the first...

  5. Water vapour variability in the high-latitude upper troposphere – Part 2: Impact of volcanic eruptions

    Directory of Open Access Journals (Sweden)

    C. E. Sioris

    2016-02-01

    Full Text Available The impact of volcanic eruptions on water vapour in the high-latitude upper troposphere is studied using deseasonalized time series based on observations by the Atmospheric Chemistry Experiment (ACE water vapour sensors, namely MAESTRO (Measurements of Aerosol Extinction in the Stratosphere and Troposphere Retrieved by Occultation and the Fourier Transform Spectrometer (ACE-FTS. The two eruptions with the greatest impact on the high-latitude upper troposphere during the time frame of this satellite-based remote sensing mission are chosen. The Puyehue–Cordón Caulle volcanic eruption in June 2011 was the most explosive in the past 24 years and is shown to be able to account for the observed (50 ± 12 % increase in water vapour in the southern high-latitude upper troposphere in July 2011 after a minor adjustment for the simultaneous influence of the Antarctic oscillation. Eyjafjallajökull erupted in the spring of 2010, increasing water vapour in the upper troposphere at northern high latitudes significantly for a period of  ∼  1 month. These findings imply that extratropical volcanic eruptions in windy environments can lead to significant perturbations to high-latitude upper tropospheric humidity mostly due to entrainment of lower tropospheric moisture by wind-blown plumes. The Puyehue–Cordón Caulle eruption must be taken into account to properly determine the magnitude of the trend in southern high-latitude upper tropospheric water vapour over the last decade.

  6. Stratospheric water vapour as tracer for Vortex filamentation in the Arctic winter 2002/2003

    Directory of Open Access Journals (Sweden)

    M. Müller

    2003-01-01

    Full Text Available Balloon-borne frost point hygrometers measured three high-resolution profiles of stratospheric water vapour above Ny-Ålesund, Spitsbergen during winter 2002/2003. The profiles obtained on 12 December 2002 and on 17 January 2003 provide an insight into the vertical distribution of water vapour in the core of the polar vortex. The water vapour sounding on 11 February 2003 was obtained within the vortex edge region of the lower stratosphere. Here, a significant reduction of water vapour mixing ratio was observed between 16 and 19 km. The stratospheric temperatures indicate that this dehydration was not caused by the presence of polar stratospheric clouds or earlier PSC particle sedimentation. Ozone observations on this day indicate a large scale movement of the polar vortex and show laminae in the same altitude range as the water vapour profile. The link between the observed water vapour reduction and filaments in the vortex edge region is indicated in the results of the semi-lagrangian advection model MIMOSA, which show that adjacent filaments of polar and mid latitude air can be identified above the Spitsbergen region. A vertical cross-section produced by the MIMOSA model reveals that the water vapour sonde flew through polar air in the lowest part of the stratosphere below 425 K, then passed through filaments of mid latitude air with lower water vapour concentrations, before it finally entered the polar vortex above 450 K. These results indicate that on 11 February 2003 the frost point hygrometer measured different water vapour concentrations as the sonde detected air with different origins. Instead of being linked to dehydration due to PSC particle sedimentation, the local reduction in the stratospheric water vapour profile was in this case caused by dynamical processes in the polar stratosphere.

  7. Optimal estimation of water vapour profiles using a combination of Raman lidar and microwave radiometer

    Science.gov (United States)

    Foth, Andreas; Pospichal, Bernhard

    2017-09-01

    In this work, a two-step algorithm to obtain water vapour profiles from a combination of Raman lidar and microwave radiometer is presented. Both instruments were applied during an intensive 2-month measurement campaign (HOPE) close to Jülich, western Germany, during spring 2013. To retrieve reliable water vapour information from inside or above the cloud a two-step algorithm is applied. The first step is a Kalman filter that extends the profiles, truncated at cloud base, to the full height range (up to 10 km) by combining previous information and current measurement. Then the complete water vapour profile serves as input to the one-dimensional variational (1D-VAR) method, also known as optimal estimation. A forward model simulates the brightness temperatures which would be observed by the microwave radiometer for the given atmospheric state. The profile is iteratively modified according to its error bars until the modelled and the actually measured brightness temperatures sufficiently agree. The functionality of the retrieval is presented in detail by means of case studies under different conditions. A statistical analysis shows that the availability of Raman lidar data (night) improves the accuracy of the profiles even under cloudy conditions. During the day, the absence of lidar data results in larger differences in comparison to reference radiosondes. The data availability of the full-height water vapour lidar profiles of 17 % during the 2-month campaign is significantly enhanced to 60 % by applying the retrieval. The bias with respect to radiosonde and the retrieved a posteriori uncertainty of the retrieved profiles clearly show that the application of the Kalman filter considerably improves the accuracy and quality of the retrieved mixing ratio profiles.

  8. ANNEALING OF POLYCRYSTALLINE THIN FILM SILICON SOLAR CELLS IN WATER VAPOUR AT SUB-ATMOSPHERIC PRESSURES

    Directory of Open Access Journals (Sweden)

    Peter Pikna

    2014-10-01

    Full Text Available Thin film polycrystalline silicon (poly-Si solar cells were annealed in water vapour at pressures below atmospheric pressure. PN junction of the sample was contacted by measuring probes directly in the pressure chamber filled with steam during passivation. Suns-VOC method and a Lock-in detector were used to monitor an effect of water vapour to VOC of the solar cell during whole passivation process (in-situ. Tested temperature of the sample (55°C – 110°C was constant during the procedure. Open-circuit voltage of a solar cell at these temperatures is lower than at room temperature. Nevertheless, voltage response of the solar cell to the light flash used during Suns-VOC measurements was good observable. Temperature dependences for multicrystalline wafer-based and polycrystalline thin film solar cells were measured and compared. While no significant improvement of thin film poly-Si solar cell parameters by annealing in water vapour at under-atmospheric pressures was observed up to now, in-situ observation proved required sensitivity to changing VOC at elevated temperatures during the process.

  9. Adsorption Of Water And Benzene Vapour In Mesoporous Materials

    Directory of Open Access Journals (Sweden)

    Paulina Taba

    2008-11-01

    Full Text Available Mesoporous materials have attracted the attention of many researchers due to the potential applications promised by the materials. This article discusses adsorption of water and benzene vapour in mesoporous materials (mesoporous silica: MCM-41, MCM-48 and their modification. MCM-41 and MCM-48 were synthesized hydrothermally at 100 oC using cethyltrimethylammonium chloride or dodecyltrimethylammonium bromide for MCM-41 (C16 or MCM-41 (C12 respectively and a mixture of cethyltrimethylammonium bromide and Triton X-100 for MCM-48 as templates. Their modifications were conducted by silylation of MCM-41 (C16 and MCM-48 with trimethylchloro silane (MCM16-TMCS and MCM48-TMCS and t-butyldimethylchloro silane (MCM16-TBDMCS and MCM48-TBDMCS. Results showed that MCM-41 and MCM-48 materials had hydrophobic features which were shown in the small amount of water adsorption at low P/P0. The hydrophobicity of samples used in this study decrease in the sequence: MCM-41 (C16 > MCM-48 > MCM-41 (C12. The hydrophobicity increased when MCM-41 and MCM-48 were silylated with TMCS or TBDMCS. All unsilylated MCM materials show higher affinity to benzene at low P/P0 than the silylated samples. The results of water and benzene adsorption showed that silylated samples are promising candidates as selective adsorbents for organic compounds.

  10. Vapour and air bubble collapse analysis in viscous compressible water

    Directory of Open Access Journals (Sweden)

    Gil Bazanini

    2001-01-01

    Full Text Available Numerical simulations of the collapse of bubbles (or cavities are shown, using the finite difference method, taking into account the compressibility of the liquid, expected to occur in the final stages of the collapse process. Results are compared with experimental and theoretical data for incompressible liquids, to see the influence of the compressibility of the water in the bubble collapse. Pressure fields values are calculated in an area of 800 x 800 mm, for the case of one bubble under the hypothesis of spherical symmetry. Results are shown as radius versus time curves for the collapse (to compare collapse times, and pressure curves in the plane, for pressure fields. Such calculations are new because of their general point of view, since the existing works do not take into account the existence of vapour in the bubble, neither show the pressure fields seen here. It is also expected to see the influence of the compressibility of the water in the collapse time, and in the pressure field, when comparing pressure values.

  11. Water vapour and ozone profiles in the midlatitude upper troposphere

    Directory of Open Access Journals (Sweden)

    G. Vaughan

    2005-01-01

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

  12. WAVE-E: The WAter Vapour European-Explorer Mission

    Science.gov (United States)

    Jimenez-LLuva, David; Deiml, Michael; Pavesi, Sara

    2017-04-01

    In the last decade, stratosphere-troposphere coupling processes in the Upper Troposphere Lower Stratosphere (UTLS) have been increasingly recognized to severely impact surface climate and high-impact weather phenomena. Weakened stratospheric circumpolar jets have been linked to worldwide extreme temperature and high-precipitation events, while anomalously strong stratospheric jets can lead to an increase in surface winds and tropical cyclone intensity. Moreover, stratospheric water vapor has been identified as an important forcing for global decadal surface climate change. In the past years, operational weather forecast and climate models have adapted a high vertical resolution in the UTLS region in order to capture the dynamical processes occurring in this highly stratified region. However, there is an evident lack of available measurements in the UTLS region to consistently support these models and further improve process understanding. Consequently, both the IPCC fifth assessment report and the ESA-GEWEX report 'Earth Observation and Water Cycle Science Priorities' have identified an urgent need for long-term observations and improved process understanding in the UTLS region. To close this gap, the authors propose the 'WAter Vapour European - Explorer' (WAVE-E) space mission, whose primary goal is to monitor water vapor in the UTLS at 1 km vertical, 25 km horizontal and sub-daily temporal resolution. WAVE-E consists of three quasi-identical small ( 500 kg) satellites (WAVE-E 1-3) in a constellation of Sun-Synchronous Low Earth Orbits, each carrying a limb sounding and cross-track scanning mid-infrared passive spectrometer (824 cm-1 to 829 cm-1). The core of the instruments builds a monolithic, field-widened type of Michelson interferometer without any moving parts, rendering it rigid and fault tolerant. Synergistic use of WAVE-E and MetOp-NG operational satellites is identified, such that a data fusion algorithm could provide water vapour profiles from the

  13. Latent heat flux measurements over complex terrain by airborne water vapour and wind lidars

    National Research Council Canada - National Science Library

    Kiemle, Christoph; Wirth, Martin; Fix, Andreas; Rahm, Stephan; Corsmeier, Ulrich; Di Girolamo, Paolo

    2011-01-01

    Vertical profiles of the latent heat flux in a convective boundary layer (CBL) are obtained for the first time over complex terrain with airborne water vapour differential absorption lidar and Doppler wind lidar...

  14. Quantifying the water vapour feedback associated with post-Pinatubo global cooling

    Energy Technology Data Exchange (ETDEWEB)

    Forster, P.M. de [NOAA Aeronomy Laboratory, Boulder, Colorado (United States); Department of Meteorology, University of Reading, Reading (United Kingdom); Collins, M. [Centre for Global Atmospheric Modelling, Department of Meteorology, University of Reading, Reading (United Kingdom)

    2004-08-01

    There is an ongoing important debate about the role of water vapour in climate change. Predictions of future climate change depend strongly on the magnitude of the water vapour feedback and until now models have almost exclusively been relied upon to quantify this feedback. In this work we employ observations of water vapour changes, together with detailed radiative calculations to estimate the water vapour feedback for the case of the Mt. Pinatubo eruption. We then compare our observed estimate with that calculated from a relatively large ensemble of simulations from a complex coupled climate model. We calculate an observed water vapour feedback parameter of -1.6 Wm{sup -2} K{sup -1}, with uncertainty placing the feedback parameter between -0.9 to -2.5 Wm{sup -2} K{sup -1}. The uncertain is principally from natural climate variations that contaminate the volcanic cooling. The observed estimates are consistent with that found in the climate model, with the ensemble average model feedback parameter being -2.0 Wm{sup -2} K{sup -1}, with a 5-95% range of -0.4 to -3.6 Wm{sup -2} K{sup -1} (as in the case of the observations, the spread is due to an inability to separate the forced response from natural variability). However, in both the upper troposphere and Southern Hemisphere the observed model water vapour response differs markedly from the observations. The observed range represents a 40%-400% increase in the magnitude of surface temperature change when compared to a fixed water vapour response and is in good agreement with values found in other studies. Variability, both in the observed value and in the climate model's feedback parameter, between different ensemble members, suggests that the long-term water vapour feedback associated with global climate change could still be a factor of 2 or 3 different than the mean observed value found here and the model water vapour feedback could be quite different from this value; although a small water vapour feedback

  15. First retrieval of global water vapour column amounts from SCIAMACHY measurements

    Directory of Open Access Journals (Sweden)

    S. Noël

    2004-01-01

    Full Text Available Global water vapour column amounts have been derived for the first time from measurements of the SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY on the European environmental satellite ENVISAT. For this purpose, two different existing retrieval algorithms have been adapted, namely the Air Mass Corrected Differential Absorption Spectroscopy (AMC-DOAS which was originally designed for GOME and the Weighting Function Modified Differential Absorption Spectroscopy (WFM-DOAS which was mainly designed for the retrieval of CH4, CO2 and CO from SCIAMACHY near-infrared spectra. Here, both methods have been applied to SCIAMACHY's nadir measurements in the near-visible spectral region around 700 nm. Taking into account a systematic offset of 10%, the results of these two methods agree within a scatter of about ±0.5 g/cm2 with corresponding SSM/I and ECMWF water vapour data. This deviation includes contributions from the temporal and spatial variability of water vapour. In fact, the mean deviation between the SCIAMACHY and the correlative data sets is much smaller: the SCIAMACHY total water vapour columns are typically about 0.15 g/cm2 lower than the SSM/I values and less than 0.1 g/cm2 lower than corresponding ECMWF data. The SCIAMACHY water vapour results agree well with correlative data not only over ocean but also over land, thus showing the capability of SCIAMACHY to derive water vapour concentrations on the global scale.

  16. Large anomalies in lower stratospheric water vapour and ice during the 2015-2016 El Niño

    Science.gov (United States)

    Avery, Melody A.; Davis, Sean M.; Rosenlof, Karen H.; Ye, Hao; Dessler, Andrew E.

    2017-06-01

    The strong and unusual El Niño of 2015-2016 produced a remarkable perturbation to the hydrologic budget of the tropical tropopause layer (14-19 km). This region regulates stratospheric water vapour, which has a direct radiative impact on surface temperatures. To first order, the coldest tropical tropopause temperature regulates the amount of water vapour entering the stratosphere by controlling the amount of dehydration in the rising air. Here we show that tropical convective cloud ice and associated cirrus sublimating at unusually high altitudes might also have a role in stratospheric hydration. The 2015-2016 El Niño produced decadal record water vapour amounts in the tropical Western Pacific, coincident with warm tropopause temperature anomalies. In the Central Pacific, convective cloud ice was observed 2 km above the anomalously cold tropopause. A trajectory-based dehydration model based on two reanalysis temperature and wind fields can account for only about 0.5-0.6 ppmv of the ~0.9 ppmv tropical lower stratospheric moistening observed during this event. This suggests that unresolved convective dynamics and/or associated sublimation of lofted ice particles also contributed to lower stratospheric moistening. These observations suggest that convective moistening could contribute to future climate change-induced stratospheric water vapour increases.

  17. The water vapour flux above Switzerland and its role in the August 2005 extreme precipitation and flooding

    Energy Technology Data Exchange (ETDEWEB)

    N' Dri Koffi, Ernest; Maetzler, Christian [Bern Univ. (Switzerland). Inst. of Applied Physics; Graham, Edward [Bern Univ. (Switzerland). Inst. of Applied Physics; University of the Highlands and Islands, Stornoway, Scotland (United Kingdom). Lews Castle College

    2013-10-15

    The water budget approach is applied to an atmospheric box above Switzerland (hereafter referred to as the 'Swiss box') to quantify the atmospheric water vapour flux using ECMWF ERA-Interim reanalyses. The results confirm that the water vapour flux through the Swiss box is highly temporally variable, ranging from 1 to 5 x 10{sup 7} kg/s during settled anticyclonic weather, but increasing in size by a factor of ten or more during high speed currents of water vapour. Overall, Switzerland and the Swiss box 'import' more water vapour than it 'exports', but the amount gained remains only a small fraction (1% to 5%) of the total available water vapour passing by. High inward water vapour fluxes are not necessarily linked to high precipitation episodes. The water vapour flux during the August 2005 floods, which caused severe damage in central Switzerland, is examined and an assessment is made of the computed water vapour fluxes compared to high spatio-temporal rain gauge and radar observations. About 25% of the incoming water vapour flux was stored in Switzerland. The computed water vapour fluxes from ECMWF data compare well with the mean rain gauge observations and the combined rain-gauge radar precipitation products. (orig.)

  18. The water vapour flux above Switzerland and its role in the August 2005 extreme precipitation and flooding

    Directory of Open Access Journals (Sweden)

    Ernest N'dri Koffi

    2013-07-01

    Full Text Available The water budget approach is applied to an atmospheric box above Switzerland (hereafter referred to as the “Swiss box” to quantify the atmospheric water vapour flux using ECMWF ERA-Interim reanalyses. The results confirm that the water vapour flux through the Swiss box is highly temporally variable, ranging from 1 to 5 · 107 kg/s during settled anticyclonic weather, but increasing in size by a factor of ten or more during high speed currents of water vapour. Overall, Switzerland and the Swiss box “import” more water vapour than it “exports”, but the amount gained remains only a small fraction (1% to 5% of the total available water vapour passing by. High inward water vapour fluxes are not necessarily linked to high precipitation episodes. The water vapour flux during the August 2005 floods, which caused severe damage in central Switzerland, is examined and an assessment is made of the computed water vapour fluxes compared to high spatio-temporal rain gauge and radar observations. About 25% of the incoming water vapour flux was stored in Switzerland. The computed water vapour fluxes from ECMWF data compare well with the mean rain gauge observations and the combined rain-gauge radar precipitation products.

  19. Novel method for water vapour monitoring using wireless communication networks measurements

    Science.gov (United States)

    David, N.; Alpert, P.; Messer, H.

    2009-04-01

    We propose a new technique for monitoring near-surface water vapour, by estimating humidity from data collected through existing wireless communication networks. Water vapour plays a crucial part in a variety of atmospheric processes. As the most influential of greenhouse gases, it absorbs long-wave terrestrial radiation. The water vapour cycle of evaporation and recondensation is a major energy redistributing mechanism transferring heat energy from the Earth's surface to the atmosphere. Additionally, humidity has an important role in weather forecasting as a key variable required for initialization of atmospheric models and hazard warning techniques. However, current methods of monitoring humidity suffer from low spatial resolution, high cost or a lack of precision when measuring near ground levels. Weather conditions and atmospheric phenomena affect the electromagnetic channel, causing attenuations to the radio signals. Thus, wireless communication networks are in effect built-in environmental monitoring facilities. The wireless microwave links, used in these networks, are widely deployed by cellular providers for backhaul communication between base stations, a few tens of meters above ground level. As a result, the proposed method can provide moisture observations at high temporal and spatial resolution. Further, the implementation cost is minimal, since the data used is already collected and saved by the cellular operators. In addition - many of these links are installed in areas where access is difficult such as orographic terrain and complex topography. As such, our method enables measurements in places that have been hard to measure in the past, or have never been measured before. The technique is restricted to weather conditions which include absence of rain, fog or clouds along the propagation path. We present results from real-data measurements taken from microwave links used in a backhaul cellular network that show very good agreement with surface

  20. The millennium water vapour drop in chemistry–climate model simulations

    Directory of Open Access Journals (Sweden)

    S. Brinkop

    2016-07-01

    Full Text Available This study investigates the abrupt and severe water vapour decline in the stratosphere beginning in the year 2000 (the "millennium water vapour drop" and other similarly strong stratospheric water vapour reductions by means of various simulations with the state-of-the-art Chemistry-Climate Model (CCM EMAC (ECHAM/MESSy Atmospheric Chemistry Model. The model simulations differ with respect to the prescribed sea surface temperatures (SSTs and whether nudging is applied or not. The CCM EMAC is able to most closely reproduce the signature and pattern of the water vapour drop in agreement with those derived from satellite observations if the model is nudged. Model results confirm that this extraordinary water vapour decline is particularly obvious in the tropical lower stratosphere and is related to a large decrease in cold point temperature. The drop signal propagates under dilution to the higher stratosphere and to the poles via the Brewer–Dobson circulation (BDC. We found that the driving forces for this significant decline in water vapour mixing ratios are tropical sea surface temperature (SST changes due to a coincidence with a preceding strong El Niño–Southern Oscillation event (1997/1998 followed by a strong La Niña event (1999/2000 and supported by the change of the westerly to the easterly phase of the equatorial stratospheric quasi-biennial oscillation (QBO in 2000. Correct (observed SSTs are important for triggering the strong decline in water vapour. There are indications that, at least partly, SSTs contribute to the long period of low water vapour values from 2001 to 2006. For this period, the specific dynamical state of the atmosphere (overall atmospheric large-scale wind and temperature distribution is important as well, as it causes the observed persistent low cold point temperatures. These are induced by a period of increased upwelling, which, however, has no corresponding pronounced signature in SSTs anomalies in the tropics

  1. Intercomparison of in-situ and remote sensing δD signals in tropospheric water vapour

    Science.gov (United States)

    Schneider, Matthias; González, Yenny; Dyroff, Christoph; Christner, Emanuel; García, Omaira; Wiegele, Andreas; Andrey, Javier; Barthlott, Sabine; Blumenstock, Thomas; Guirado, Carmen; Hase, Frank; Ramos, Ramon; Rodríguez, Sergio; Sepúveda, Eliezer

    2014-05-01

    The main mission of the project MUSICA (MUlti-platform remote Sensing of Isotopologues for investigating the Cycle of Atmospheric water) is the generation of a quasi-global tropospheric water vapour isototopologue dataset of a good and well-documented quality. We present a first empirical validation of MUSICA's remote sensing δD products (ground-based FTIR within NDACC, Network for the Detection of Atmospheric Composition Change, and space-based with IASI, Infrared Atmospheric Sounding Interferometer, flown on METOP). As reference we use in-situ measurements made on the island of Tenerife at two different altitudes (2370 and 3550 m a.s.l., using two Picarro L2120-i water isotopologue analyzers) and aboard an aircraft (between 200 and 6800 m a.s.l., using the homemade ISOWAT instrument).

  2. Continuous measurements of isotopic composition of water vapour on the East Antarctic Plateau

    Directory of Open Access Journals (Sweden)

    M. Casado

    2016-07-01

    Full Text Available Water stable isotopes in central Antarctic ice cores are critical to quantify past temperature changes. Accurate temperature reconstructions require one to understand the processes controlling surface snow isotopic composition. Isotopic fractionation processes occurring in the atmosphere and controlling snowfall isotopic composition are well understood theoretically and implemented in atmospheric models. However, post-deposition processes are poorly documented and understood. To quantitatively interpret the isotopic composition of water archived in ice cores, it is thus essential to study the continuum between surface water vapour, precipitation, surface snow and buried snow. Here, we target the isotopic composition of water vapour at Concordia Station, where the oldest EPICA Dome C ice cores have been retrieved. While snowfall and surface snow sampling is routinely performed, accurate measurements of surface water vapour are challenging in such cold and dry conditions. New developments in infrared spectroscopy enable now the measurement of isotopic composition in water vapour traces. Two infrared spectrometers have been deployed at Concordia, allowing continuous, in situ measurements for 1 month in December 2014–January 2015. Comparison of the results from infrared spectroscopy with laboratory measurements of discrete samples trapped using cryogenic sampling validates the relevance of the method to measure isotopic composition in dry conditions. We observe very large diurnal cycles in isotopic composition well correlated with temperature diurnal cycles. Identification of different behaviours of isotopic composition in the water vapour associated with turbulent or stratified regime indicates a strong impact of meteorological processes in local vapour/snow interaction. Even if the vapour isotopic composition seems to be, at least part of the time, at equilibrium with the local snow, the slope of δD against δ18O prevents us from identifying

  3. Response of water vapour D-excess to land-atmosphere interactions in a semi-arid environment

    KAUST Repository

    Parkes, Stephen

    2016-06-30

    The stable isotopic composition of water vapour provides information about moisture sources and processes difficult to obtain with traditional measurement techniques. Recently, it has been proposed that the D-excess of water vapour can provide a diagnostic tracer of continental moisture recycling. However, D-excess exhibits a diurnal cycle that has been observed across a variety of ecosystems and may be influenced by a range of processes beyond regional-scale moisture recycling, including local evaporation (ET) fluxes. There is a lack of measurements of D-excess in evaporation (ET) fluxes, which has made it difficult to assess how ET fluxes modify the Dexcess in water vapour (dv). With this in mind, we employed a chamber-based approach to directly measure D-excess in ET (dET) fluxes. We show that ET fluxes imposed a negative forcing on the ambient vapour and could not explain the higher daytime dv values. The low dET observed here was sourced from a soil water pool that had undergone an extended drying period, leading to low D-excess in the soil moisture pool. A strong correlation between daytime dv and locally measured relative humidity was consistent with an oceanic moisture source, suggesting that remote hydrological processes were the major contributor to daytime dv variability. During the early evening, ET fluxes into a shallow nocturnal inversion layer caused a lowering of dv values near the surface. In addition, transient mixing of vapour with a higher D-excess from above the nocturnal inversion modified these values, causing large variability during the night. These results indicate dET can generally be expected to show

  4. A rapid method for the sampling of atmospheric water vapour for isotopic analysis.

    Science.gov (United States)

    Peters, Leon I; Yakir, Dan

    2010-01-01

    Analysis of the stable isotopic composition of atmospheric moisture is widely applied in the environmental sciences. Traditional methods for obtaining isotopic compositional data from ambient moisture have required complicated sampling procedures, expensive and sophisticated distillation lines, hazardous consumables, and lengthy treatments prior to analysis. Newer laser-based techniques are expensive and usually not suitable for large-scale field campaigns, especially in cases where access to mains power is not feasible or high spatial coverage is required. Here we outline the construction and usage of a novel vapour-sampling system based on a battery-operated Stirling cycle cooler, which is simple to operate, does not require any consumables, or post-collection distillation, and is light-weight and highly portable. We demonstrate the ability of this system to reproduce delta(18)O isotopic compositions of ambient water vapour, with samples taken simultaneously by a traditional cryogenic collection technique. Samples were collected over 1 h directly into autosampler vials and were analysed by mass spectrometry after pyrolysis of 1 microL aliquots to CO. This yielded an average error of distillation lines, slurry maintenance or mains power is not feasible. Copyright 2009 John Wiley & Sons, Ltd.

  5. Spatio-Temporal Estimation of Integrated Water Vapour Over the Malaysian Peninsula during Monsoon Season

    Science.gov (United States)

    Salihin, S.; Musa, T. A.; Radzi, Z. Mohd

    2017-10-01

    This paper provides the precise information on spatial-temporal distribution of water vapour that was retrieved from Zenith Path Delay (ZPD) which was estimated by Global Positioning System (GPS) processing over the Malaysian Peninsular. A time series analysis of these ZPD and Integrated Water Vapor (IWV) values was done to capture the characteristic on their seasonal variation during monsoon seasons. This study was found that the pattern and distribution of atmospheric water vapour over Malaysian Peninsular in whole four years periods were influenced by two inter-monsoon and two monsoon seasons which are First Inter-monsoon, Second Inter-monsoon, Southwest monsoon and Northeast monsoon.

  6. Intercomparison of atmospheric water vapour measurements at a Canadian High Arctic site

    Science.gov (United States)

    Weaver, Dan; Strong, Kimberly; Schneider, Matthias; Rowe, Penny M.; Sioris, Chris; Walker, Kaley A.; Mariani, Zen; Uttal, Taneil; McElroy, C. Thomas; Vömel, Holger; Spassiani, Alessio; Drummond, James R.

    2017-08-01

    Water vapour is a critical component of the Earth system. Techniques to acquire and improve measurements of atmospheric water vapour and its isotopes are under active development. This work presents a detailed intercomparison of water vapour total column measurements taken between 2006 and 2014 at a Canadian High Arctic research site (Eureka, Nunavut). Instruments include radiosondes, sun photometers, a microwave radiometer, and emission and solar absorption Fourier transform infrared (FTIR) spectrometers. Close agreement is observed between all combination of datasets, with mean differences ≤ 1.0 kg m-2 and correlation coefficients ≥ 0.98. The one exception in the observed high correlation is the comparison between the microwave radiometer and a radiosonde product, which had a correlation coefficient of 0.92.A variety of biases affecting Eureka instruments are revealed and discussed. A subset of Eureka radiosonde measurements was processed by the Global Climate Observing System (GCOS) Reference Upper Air Network (GRUAN) for this study. Comparisons reveal a small dry bias in the standard radiosonde measurement water vapour total columns of approximately 4 %. A recently produced solar absorption FTIR spectrometer dataset resulting from the MUSICA (MUlti-platform remote Sensing of Isotopologues for investigating the Cycle of Atmospheric water) retrieval technique is shown to offer accurate measurements of water vapour total columns (e.g. average agreement within -5.2 % of GRUAN and -6.5 % of a co-located emission FTIR spectrometer). However, comparisons show a small wet bias of approximately 6 % at the high-latitude Eureka site. In addition, a new dataset derived from Atmospheric Emitted Radiance Interferometer (AERI) measurements is shown to provide accurate water vapour measurements (e.g. average agreement was within 4 % of GRUAN), which usefully enables measurements to be taken during day and night (especially valuable during polar night).

  7. Distribution of tritium in water vapour and precipitation around Wolsung nuclear power plant.

    Science.gov (United States)

    Chae, Jung-Seok; Lee, Sang-Kuk; Kim, Yongjae; Lee, Jung-Min; Cho, Heung-Joon; Cho, Yong-Woo; Yun, Ju-Yong

    2011-07-01

    The distribution of tritium in water vapour and precipitation with discharge of tritiated water vapour and meteorological factors was studied around the Wolsung nuclear power plant (NPP) site during the period 2004-2008. The tritium concentrations in atmospheric water vapour and precipitation had a temporal variation with relatively high values in the early summer. Spatial distribution of tritium concentrations was affected by various factors such as distance from the NPP site, wind direction, tritium discharge into the atmosphere and atmospheric dispersion factor. The annual mean concentrations of atmospheric HTO and precipitation were correlated with the amount of gaseous tritium released from the Wolsung NPP. The tritium concentrations in precipitation decrease exponentially with an increase of the distance from the Wolsung NPP site.

  8. Global distributions of water vapour isotopologues retrieved from IMG/ADEOS data

    Directory of Open Access Journals (Sweden)

    H. Herbin

    2007-07-01

    Full Text Available The isotopologic composition of water vapour in the atmosphere provides valuable information on many climate, chemical and dynamical processes. The accurate measurements of the water isotopologues by remote-sensing techniques remains a challenge, due to the large spatial and temporal variations. Simultaneous profile retrievals of the main water isotopologues (i.e. H216O, H218O and HDO and their ratios are presented here for the first time, along their retrieved global distributions. The results are obtained by exploiting the high resolution infrared spectra recorded by the Interferometric Monitor for Greenhouse gases (IMG instrument, which has operated in the nadir geometry onboard the ADEOS satellite between 1996 and 1997. The retrievals are performed on cloud-free radiances, measured during ten days of April 1997, considering two atmospheric windows (1205–1228 cm−1; 2004–2032 cm−1 and using a line-by-line radiative transfer model and an inversion procedure based on the Optimal Estimation Method (OEM. Characterizations in terms of vertical sensitivity and error budget are provided. We show that a relatively high vertical resolution is achieved for H216O (~4–5 km, and that the retrieved profiles are in fair agreement with local sonde measurements, at different latitudes. The retrieved global distributions of H216O, H218O, HDO and their ratios are presented and found to be consistent with previous experimental studies and models. The Ocean-Continent difference, the latitudinal and vertical dependence of the water vapour amount and the isotopologic depletion are notably well reproduced. Others trends, possibly related to small-scale variations in the vertical profiles are also discussed. Despite the difficulties encountered for computing accurately the isotopologic ratios, our results demonstrate the ability

  9. Water vapour emission in vegetable fuel: absorption cell measurements and detection limits of our CO II Dial system

    Science.gov (United States)

    Bellecci, C.; De Leo, L.; Gaudio, P.; Gelfusa, M.; Lo Feudo, T.; Martellucci, S.; Richetta, M.

    2006-09-01

    Forest fires can be the cause of serious environmental and economic damages. For this reason a considerable effort has been directed toward the forest protection and fire fighting. In the early forest fire detection, Lidar technique present considerable advantages compared to the passive detection methods based on infrared cameras currently in common use, due its higher sensitivity and ability to accurately locate the fire. The combustion phase of the vegetable matter causes a great amount of water vapour emission, thus the water molecule behaviour will be studied to obtain a fire detection system ready and efficient also before the flame propagation. A first evaluation of increment of the water vapour concentration compared to standard one will be estimated by a numerical simulation. These results will be compared with the experimental measurements carried out into a cell with a CO II Dial system, burning different kinds of vegetable fuel. Our results and their comparison will be reported in this paper.

  10. Upper tropospheric water vapour variability at high latitudes – Part 1: Influence of the annular modes

    Directory of Open Access Journals (Sweden)

    C. E. Sioris

    2016-03-01

    Full Text Available Seasonal and monthly zonal medians of water vapour in the upper troposphere and lower stratosphere (UTLS are calculated for both Atmospheric Chemistry Experiment (ACE instruments for the northern and southern high-latitude regions (60–90° N and 60–90° S. Chosen for the purpose of observing high-latitude processes, the ACE orbit provides sampling of both regions in 8 of 12 months of the year, with coverage in all seasons. The ACE water vapour sensors, namely MAESTRO (Measurements of Aerosol Extinction in the Stratosphere and Troposphere Retrieved by Occultation and the Fourier Transform Spectrometer (ACE-FTS are currently the only satellite instruments that can probe from the lower stratosphere down to the mid-troposphere to study the vertical profile of the response of UTLS water vapour to the annular modes. The Arctic oscillation (AO, also known as the northern annular mode (NAM, explains 64 % (r = −0.80 of the monthly variability in water vapour at northern high latitudes observed by ACE-MAESTRO between 5 and 7 km using only winter months (January to March, 2004–2013. Using a seasonal time step and all seasons, 45 % of the variability is explained by the AO at 6.5 ± 0.5 km, similar to the 46 % value obtained for southern high latitudes at 7.5 ± 0.5 km explained by the Antarctic oscillation or southern annular mode (SAM. A large negative AO event in March 2013 produced the largest relative water vapour anomaly at 5.5 km (+70 % over the ACE record. A similarly large event in the 2010 boreal winter, which was the largest negative AO event in the record (1950–2015, led to > 50 % increases in water vapour observed by MAESTRO and ACE-FTS at 7.5 km.

  11. WATER VAPOUR PERMEABILITY PROPERTIES OF CELLULAR WOOD MATERIAL AND CONDENSATION RISK OF COMPOSITE PANEL WALLS

    Directory of Open Access Journals (Sweden)

    Janis IEJAVS

    2016-09-01

    Full Text Available Invention of light weight cellular wood material (CWM with a trade mark of Dendrolight is one of innovations in wood industry of the last decade. The aim of the research was to define the water vapour permeability properties of CWM and to analyse the condensation risk of various wall envelopes where solid wood cellular material is used. To determine the water vapour permeability of CWM, test samples were produced in the factory using routine production technology and tested according to the standard EN 12086:2014. Water vapour permeability factor (μ and other properties of six different configurations of CWM samples were determined. Using the experimental data the indicative influence of geometrical parameters such as lamella thickness, number of lamellas and material direction were investigated and evaluated. To study the condensation risk within the wall envelope containing CWM calculation method given in LVS EN ISO 13788:2012 was used. To ease the calculation process previously developed JavaScript calculation software that had only capability to calculate thermal transmittance was extended so that condensation risk in multi-layer composite walls can be analysed. Water vapour permeability factor in CWM is highly direction dependant. If parallel and perpendicular direction of CWM is compared the value of water vapour permeability factor can differentiate more than two times. Another significant factor for condensation risk analysis is overall thickness of CWM since it directly influences the equivalent air layer thickness. The influence of other factors such as lamella thickness, or groove depth is minor when water vapour permeability properties are compared. From the analysis of CWM performance in building envelope it can be concluded that uninsulated CWM panels used during winter months will pose the risk of condensation damage to structure, but the risk can be reduced or prevented if insulation layer is applied to the CWM panel wall

  12. Measurement of water vapour transport through a porous non-hygroscopic material in a temperature gradient

    DEFF Research Database (Denmark)

    Hansen, Thor; Padfield, Tim; Hansen, Kurt Kielsgaard

    2014-01-01

    This was an experiment to identify the driving potential for water vapour diffusion through porous materials in a temperature gradient. The specimen of mineral fibre insulation was placed between a space with controlled temperature and relative humidity and a space with a controlled, higher...... temperature, and a measured but not controlled relative humidity (RH). This assembly was allowed to reach equilibrium with no vapour movement between the spaces, as tested by a constant RH on each side and by zero flux of water vapour measured in the cold side chamber. The RH and temperature values were...... be tested experimentally in this way, but it is reasonable to assume that concentration is the driving potential. The close equality of the concentrations makes it unnecessary to invoke temperature difference as a third possible potential for driving diffusion....

  13. Initial evaluation of airborne water vapour measurements by the IAGOS-GHG CRDS system

    Science.gov (United States)

    Filges, Annette; Gerbig, Christoph; Smit, Herman G. J.; Krämer, Martina; Spelten, Nicole

    2013-04-01

    Accurate and reliable airborne measurements of water vapour are still a challenge. Presently, no airborne humidity sensor exists that covers the entire range of water vapour content between the surface and the upper troposphere/lower stratosphere (UT/LS) region with sufficient accuracy and time resolution. Nevertheless , these data are a pre-requisite to study the underlying processes in the chemistry and physics of the atmosphere. The DENCHAR project (Development and Evaluation of Novel Compact Hygrometer for Airborne Research) addresses this deficit by developing and characterizing novel or improved compact airborne hygrometers for different airborne applications within EUFAR (European Facility for Airborne Research). As part of the DENCHAR inter-comparison campaign in Hohn (Germany), 23 May - 1 June 2011, a commercial gas analyzer (G2401-m, Picarro Inc.,US), based on cavity ring-down spectroscopy (CRDS), was installed on a Learjet to measure water vapour, CO2, CH4 and CO. The CRDS components are identical to those chosen for integration aboard commercial airliner within IAGOS (In-service Aircraft for a Global Observing System). Thus the campaign allowed for the initial assessment validation of the long-term IAGOS H2O measurements by CRDS against reference instruments with a long performance record (FISH, the Fast In-situ Stratospheric Hygrometer, and CR2 frostpoint hygrometer, both research centre Juelich). The inlet system, a one meter long 1/8" FEP-tube connected to a Rosemount TAT housing (model 102BX, deiced) installed on a window plate of the aircraft, was designed to eliminate sampling of larger aerosols, ice particles, and water droplets, and provides about 90% of ram-pressure. In combination with a lowered sample flow of 0.1 slpm (corresponding to a 4 second response time), this ensured a fully controlled sample pressure in the cavity of 140 torr throughout an aircraft altitude operating range up to 12.5 km without the need of an upstream sampling pump

  14. Water vapour intercomparison effort in the frame of HyMeX-SOP1

    Science.gov (United States)

    Summa, Donato; Di Girolamo, Paolo; Stelitano, Dario; Cacciani, Marco; Flamant, Cyrille; Chazette, Patrick; Ducrocq, Véronique; Nuret, Mathieu; Fourié, Nadia; Richard, Evelyne

    2014-05-01

    A water vapour intercomparison effort, involving airborne and ground-based water vapour lidar systems and mesoscale models, was carried out in the framework of the international HyMeX (Hydrological cycle in the Mediterranean Experiment) dedicated to the hydrological cycle and related high-impact events. Within HyMeX, a major field campaign was dedicated to heavy precipitation and flash flood events from 5 September to 6 November 2012. The 2 month field campaign took place over the Northwestern Mediterranean Sea and its surrounding coastal regions in France, Italy, and Spain. The main objective of this work is to provide accurate error estimates for the lidar systems i.e. the ground-based Raman lidar BASIL and the CNRS DIAL Leandre 2 on board the ATR42, as well as use BASIL data to validate mesoscale model results from the MESO NH and Arome WMED. The effort will benefit from the few dedicated ATR42 flights in the frame of the EUFAR Project "WaLiTemp". In the present work our attention was focused on two specific case studies: 13 September and 2 October in the altitude region 0.5 - 5.5 km. Comparisons between the ground-based Raman lidar BASIL and the airborne CNRS DIAL indicate a mean relative bias between the two sensors of 6.5%, while comparisons between BASIL and CNRS DIAL vs. the radiosondes indicate a bias of 2.6 and -3.5 %, respectively. The bias of BASIL vs. the ATR insitu sensor indicate a bias of -20.4 %. Specific attention will also be dedicated to the WALI/BASIL intercomparison effort which took place in Candillargues on 30 October 2012. Specific results from this intercomparison effort and from the intercomparison between BASIL and Meso-NH/AROME-WMed will be illustrated and discussed at the Conference.

  15. Thermal diffusion of water vapour in porous materials: fact or fiction?

    DEFF Research Database (Denmark)

    Janssen, Hans

    2011-01-01

    The reliable evaluation of moisture transfer in porous materials is essential in many engineering applications, among which building science. One key aspect is a correct description of moisture flow phenomena and their transport potentials. While different issues can be debated in that respect...... its negligible magnitude. It can in conclusion be stated that thermal diffusion is of no importance for building science applications, leaving vapour pressure as the sole significant transport potential for the diffusion of water vapour in porous materials. (C) 2010 Elsevier Ltd. All rights reserved....

  16. Temperature-dependent transport mechanisms through PE-CVD coatings: comparison of oxygen and water vapour

    Science.gov (United States)

    Kirchheim, D.; Wilski, S.; Jaritz, M.; Mitschker, F.; Gebhard, M.; Brochhagen, M.; Böke, M.; Benedikt, Jan; Awakowicz, P.; Devi, A.; Hopmann, Ch; Dahlmann, R.

    2017-10-01

    When it comes to thin coatings such as plasma-enhanced chemical vapour deposition or plasma-enhanced atomic layer deposition coatings on substrates of polymeric material, existing models often describe transport through these thin coatings as mainly driven by transport through defects of different sizes. However, temperature-dependent measurements of permeation could not confirm this hypothesis and instead gaseous transport through these thin coatings was found to more likely to occur through the molecular structure. This paper correlates existing transport models with data from oxygen transmission experiments and puts recent investigations for water vapour transmission mechanisms into context for a better understanding of gaseous transport through thin coatings.

  17. Reaction of soda-lime-silica glass melt with water vapour at melting temperatures

    Czech Academy of Sciences Publication Activity Database

    Vernerová, Miroslava; Kloužek, Jaroslav; Němec, Lubomír

    2015-01-01

    Roč. 416, MAY 15 (2015), s. 21-30 ISSN 0022-3093 R&D Projects: GA TA ČR TA01010844 Institutional support: RVO:67985891 Keywords : glass melt * sulfate * water vapour * bubble nucleation * melt foaming * glass melting Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass Impact factor: 1.825, year: 2015

  18. Behaviour of carbon dioxide and water vapour flux densities from a disturbed raised peat bog

    NARCIS (Netherlands)

    Nieveen, J.P.; Jacobs, A.F.G.

    2002-01-01

    Measurements of carbon dioxide and water vapour flux densities were carried out for a disturbed raised peat bog in the north of the Netherlands during an 18 month continuous experiment. Tussock grass (sp. Molinea caerulae) mainly dominated the vegetation of the bog area. The maximum leaf area index

  19. The time variation in infrared water-vapour bands in Mira variables

    NARCIS (Netherlands)

    Matsuura, M; Yamamura, [No Value; Cami, J; Onaka, T; Murakami, H; Yamamura, I.

    The time variation in the water-vapour bands in oxygen-rich Mira variables has been investigated using multi-epoch ISO/SWS spectra of four Mira variables in the 2.5-4.0 mum region. All four stars show H2O bands in absorption around minimum in the visual light curve. At maximum, H2O emission features

  20. Water vapour rises from the cooling towers for the ATLAS detector at Point 1

    CERN Multimedia

    Brice, Maximilien

    2015-01-01

    Electronics on the ATLAS detector produce heat when the experiment is running. An elaborate cooling system keeps the detector from overheating. On the surface, the warm water vapour that rises from the detector 100metres underground is clearly visible from the ATLAS cooling towers on the CERN Meyrin site in Switzerland.

  1. Analysis of carbon dioxide, water vapour and energy fluxes over an ...

    Indian Academy of Sciences (India)

    Analysis of carbon dioxide, water vapour and energy fluxes over an Indian teak mixed deciduous forest for winter and summer months using eddy covariance technique ... Eddy covariance; Indian deciduous forests; CO2 flux; heat flux. ... National Remote Sensing Centre (ISRO), Balanagar, Hyderabad 500 037, India.

  2. Analysis of carbon dioxide, water vapour and energy fluxes over an ...

    Indian Academy of Sciences (India)

    temperate grassland ecosystem; Bound.-Layer Meteorol. 52 135–149. Mahrt L and Dean V 2002 Relationship of area-averaged carbon dioxide and water vapour fluxes to atmospheric variables; Agric. For. Meteor. 112 195–202. Ohtaki E 1984 Application of an infrared carbon dioxide and humidity instrument to studies of ...

  3. Study and mitigation of calibration error sources in a water vapour Raman lidar

    Science.gov (United States)

    David, Leslie; Bock, Olivier; Bosser, Pierre; Thom, Christian; Pelon, Jacques

    2014-05-01

    The monitoring of water vapour throughout the atmosphere is important for many scientific applications (weather forecasting, climate research, calibration of GNSS altimetry measurements). Measuring water vapour remains a technical challenge because of its high variability in space and time. The major issues are achieving long-term stability (e.g., for climate trends monitoring) and high accuracy (e.g. for calibration/validation applications). LAREG and LOEMI at Institut National de l'Information Géographique et Forestière (IGN) have developed a mobile scanning water vapour Raman lidar in collaboration with LATMOS at CNRS. This system aims at providing high accuracy water vapour measurements throughout the troposphere for calibrating GNSS wet delay signals and thus improving vertical positioning. Current developments aim at improving the calibration method and long term stability of the system to allow the Raman lidar to be used as a reference instrument. The IGN-LATMOS lidar was deployed in the DEMEVAP (Development of Methodologies for Water Vapour Measurement) campaign that took place in 2011 at the Observatoire de Haute Provence. The goals of DEMEVAP were to inter-compare different water vapour sounding techniques (lidars, operational and research radiosondes, GPS,…) and to study various calibration methods for the Raman lidar. A significant decrease of the signals and of the calibration constants of the IGN-LATMOS Raman lidar has been noticed all along the campaign. This led us to study the likely sources of uncertainty and drifts in each part of the instrument: emission, reception and detection. We inventoried several error sources as well as instability sources. The impact of the temperature dependence of the Raman lines on the filter transmission or the fluorescence in the fibre, are examples of the error sources. We investigated each error source and each instability source (uncontrolled laser beam jitter, temporal fluctuations of the photomultiplier

  4. Usefulness of satellite water vapour imagery in forecasting strong convection: A flash-flood case study

    Science.gov (United States)

    Georgiev, Christo G.; Kozinarova, Gergana

    Using a case study of a severe convective event as an example, a framework for interpreting 6.2 µm channel satellite imagery that enables to indicate upper-level conditioning of the convective environment is presented and discussed. In order to illustrate the approach, all convective cells during the summer of 2007 that produced precipitations over Bulgaria are considered. They are classified regarding the observed moisture pattern in mid-upper levels as well as the low-level conditions of air humidity and convergence of the flow. Water vapour (WV) images are used to study the evolution of the upper-level moist and dry structures. The proposed interpretation is that the role of the upper-level dry boundaries identified in the WV imagery as favoured areas for the initiation of deep moist convection cannot be understood (and hence cannot be forecasted accurately) by considering them in isolation from the dynamic rate at which they are maintained. The paper examines the 23 June 2006 flash flood in Sofia city as a case, in which the operational forecast of the National Institute of Meteorology and Hydrology of Bulgaria based on the mesoscale NWP model ALADIN underestimated the severity of the convective process. A comparison between the satellite water vapour imagery and the corresponding geopotential field of the dynamical tropopause, expressed in terms of potential vorticity (PV), shows an error in the performance of the ARPEGE operational numerical model. There is an obvious mismatch between the PV anomaly structure and the dry zone of the imagery. The forecast field shows underestimation of the tropopause height gradient and displacement of the PV anomaly to the southwest of the real position seen in the satellite image. It is concluded that the observed poor forecast is a result of the ARPEGE failure to treat correctly the interaction between the PV anomaly and the low-level warm anomaly.

  5. Water mobility within arabinoxylan and β-glucan films studied by NMR and dynamic vapour sorption.

    Science.gov (United States)

    Ying, Ruifeng; Barron, Cécile; Saulnier, Luc; Rondeau-Mouro, Corinne

    2011-11-01

    The main purpose of this research was to determine the impact of the structure and organisation of polysaccharides on the hydration properties of the cell walls of cereal grains. In order to remodel the lamellar assembly of arabinoxylan (AX) and (1 → 3)(1 → 4)-β-D-glucan (BG) within the endosperm cell walls, films were prepared and analysed using dynamic vapour sorption and time domain nuclear magnetic resonance spectroscopy. The water diffusivities within the AX and BG films were measured at 20 °C by observing the water sorption kinetics within a mathematical model based on Fick's second law. The evolution of spin-spin relaxation times of water protons measured by increasing the temperature is explained by the additional contributions of motion of the protons of polysaccharides and/or rapid chemical exchanges of protons between water and hydroxyl groups of polysaccharides. The difference between patterns of water behaviour within the AX and BG films can be related to the difference in their nanostructures. The smaller nanopores of the BG films cause their nanostructure to be more compact. Copyright © 2011 Society of Chemical Industry.

  6. Long-term series of tropospheric water vapour amounts and HDO/H2O ratio profiles above Jungfraujoch.

    Science.gov (United States)

    Lejeune, B.; Mahieu, E.; Schneider, M.; Hase, F.; Servais, C.; Demoulin, P.

    2012-04-01

    Water vapour is a crucial climate variable involved in many processes which widely determine the energy budget of our planet. In particular, water vapour is the dominant greenhouse gas in the Earth's atmosphere and its radiative forcing is maximum in the middle and upper troposphere. Because of the extremely high variability of water vapour concentration in time and space, it is challenging for the available relevant measurement techniques to provide a consistent data set useful for trend analyses and climate studies. Schneider et al. (2006a) showed that ground-based Fourier Transform Infrared (FTIR) spectroscopy, performed from mountain observatories, allows for the detection of H2O variabilities up to the tropopause. Furthermore, the FTIR measurements allow the retrieval of HDO amounts and therefore the monitoring of HDO/H2O ratio profiles whose variations act as markers for the source and history of the atmospheric water vapour. In the framework of the MUSICA European project (Multi-platform remote Sensing of Isotopologues for investigating the Cycle of Atmospheric water, http://www.imk-asf.kit.edu/english/musica.php), a new approach has been developed and optimized by M. Schneider and F. Hase, using the PROFFIT algorithm, to consistently retrieve tropospheric water vapour profiles from high-resolution ground-based infrared solar spectra and so taking benefit from available long-term data sets of ground-based observations. The retrieval of the water isotopologues is performed on a logarithmic scale from 14 micro-windows located in the 2600-3100 cm-1 region. Other important features of this new retrieval strategy are: a speed dependant Voigt line shape model, a joint temperature profile retrieval and an interspecies constraint for the HDO/H2O profiles. In this contribution, we will combine the quality of the MUSICA strategy and of our observations, which are recorded on a regular basis with FTIR spectrometers, under clear-sky conditions, at the NDACC site

  7. Chemical vapour etching-based porous silicon and grooving: Application in silicon solar cells processing

    Energy Technology Data Exchange (ETDEWEB)

    Ben Rabha, M.; Boujmil, M.F.; Saadoun, M.; Bessais, B. [Institut National de Recherche Scientifique et Technique, Laboratoire de Photovoltaique et des Semiconducteurs, BP 95, 2050 Hammam-Lif (Tunisia)

    2005-06-01

    Sponge like porous silicon (PS) was formed by a simple and low cost chemical vapour etching (CVE) method and applied in polycrystalline silicon (mc-Si) solar cells processing. The CVE method consists of exposing Si wafers to HNO{sub 3}/HF vapours. It was shown that 8 min of HNO{sub 3}/HF CVE (volume ratio = 1/7) is sufficient to form optimized PS layers on the emitter of mc-Si cells. The CVE-based PS can simultaneously passivate the Si surface and serves as an effective antireflection coating (ARC). As a result, the reflectivity decreases by about 60% of its initial value and the internal quantum efficiency is improved, particularly in the short wavelength region. For acid vapours rich in HNO{sub 3} (HNO{sub 3}/HF >1/4), the CVE method favours the formation of a (NH{sub 4}){sub 2}SiF{sub 6} powder, which is highly soluble in water. These findings let us achieve anisotropic grooving that enables to groove mc-Si wafers locally and in depth using an adequate anti-acid mask. The CVE - based grooving technique was used to form buried metallic contacts on the rear and frontal surface of the Si wafer in order to improve the current collection in mc-Si solar cells. No alteration of the spectral response in the long wavelength range was observed in mc-Si cells with rear-buried contacts. Adjustments of theoretical spectral responses to experimental ones show an increase in the effective electron diffusion length (Ln), which was attributed to Al gettering (passivation) at grain boundaries and to the reduction of the effective thickness of the base of the cells. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  8. The water vapour flux above Switzerland and its role in the August 2005 extreme precipitation and flooding

    OpenAIRE

    Ernest N'Dri Koffi; Edward Graham; Andchristian Mätzler

    2013-01-01

    The water budget approach is applied to an atmospheric box above Switzerland (hereafter referred to as the “Swiss box”) to quantify the atmospheric water vapour flux using ECMWF ERA-Interim reanalyses. The results confirm that the water vapour flux through the Swiss box is highly temporally variable, ranging from 1 to 5 · 107 kg/s during settled anticyclonic weather, but increasing in size by a factor of ten or more during high speed currents of water vapour. Overall, Switzerland and the ...

  9. Dynamic water vapour sorption in gluten and starch films

    NARCIS (Netherlands)

    Oliver, L.; Meinders, M.B.J.

    2011-01-01

    Water sorption of gluten and wheat starch films as a function of water activity was studied using gravimetric step-change sorption experiments. Films of different thicknesses were used with the aim to vary the characteristic diffusion time and to get insights in the contribution of the polymer-chain

  10. Response of water vapour D-excess to land–atmosphere interactions in a semi-arid environment

    KAUST Repository

    Parkes, Stephen

    2017-01-27

    The stable isotopic composition of water vapour provides information about moisture sources and processes difficult to obtain with traditional measurement techniques. Recently, it has been proposed that the D-excess of water vapour (d =δH-8× δO) can provide a diagnostic tracer of continental moisture recycling. However, D-excess exhibits a diurnal cycle that has been observed across a variety of ecosystems and may be influenced by a range of processes beyond regional-scale moisture recycling, including local evaporation (ET) fluxes. There is a lack of measurements of D-excess in evaporation (ET) fluxes, which has made it difficult to assess how ET fluxes modify the Dexcess in water vapour (d). With this in mind, we employed a chamber-based approach to directly measure D-excess in ET (d) fluxes. We show that ET fluxes imposed a negative forcing on the ambient vapour and could not explain the higher daytime d values. The low d observed here was sourced from a soil water pool that had undergone an extended drying period, leading to low D-excess in the soil moisture pool. A strong correlation between daytime d and locally measured relative humidity was consistent with an oceanic moisture source, suggesting that remote hydrological processes were the major contributor to daytime d variability. During the early evening, ET fluxes into a shallow nocturnal inversion layer caused a lowering of d values near the surface. In addition, transient mixing of vapour with a higher D-excess from above the nocturnal inversion modified these values, causing large variability during the night. These results indicate d can generally be expected to show large spatial and temporal variability and to depend on the soil moisture state. For long periods between rain events, common in semi-arid environments, ET would be expected to impose negative forcing on the surface d. Spatial and temporal variability of D-excess in ET fluxes therefore needs to be considered when using d to study

  11. Partitioning understory evapotranspiration in semi-arid ecosystems in Namibia using the isotopic composition of water vapour

    Science.gov (United States)

    de Blécourt, Marleen; Gaj, Marcel; Holtorf, Kim-Kirsten; Gröngröft, Alexander; Brokate, Ralph; Himmelsbach, Thomas; Eschenbach, Annette

    2016-04-01

    In dry environments with a sparse vegetation cover, understory evapotranspiration is a major component of the ecosystem water balance. Consequently, knowledge on the size of evapotranspiration fluxes and the driving factors is important for our understanding of the hydrological cycle. Understory evapotranspiration is made up of soil evaporation and plant transpiration. Soil evaporation can be measured directly from patches free of vegetation. However, when understory vegetation is present distinguishing between soil evaporation and plant transpiration is challenging. In this study, we aim to partition understory evapotranspiration based on an approach that combines the measurements of water-vapour fluxes using the closed chamber method with measurements of the isotopic composition of water vapour. The measurements were done in the framework of SASSCAL (Southern African Science Service Centre for Climate Change and Adaptive Land Management). The study sites were located in three different semi-arid ecosystems in Namibia: thornbush savanna, Baikiaea woodland and shrubland. At each site measurements were done under tree canopies as well as at unshaded areas between the canopies. We measured evaporation from the bare soil and evapotranspiration from patches covered with herbaceous species and shrubs using a transparent chamber connected with an infrared gas analyser (LI-8100A, LICOR Inc.). The stable isotope composition of water vapour inside the chamber and depth profiles of soil water stable isotopes were determined in-situ using a tuneable off-axis integrated cavity output spectroscope (OA-ICOS, Los Gatos Research, DLT 100). Xylem samples were extracted using the cryogenic vacuum extraction method and the isotopic composition of the extracted water was measured subsequently with a cavity-ring-down spectrometer (CRDS L2120-i, Picarro Inc.). We will present the quantified fluxes of understory evapotranspiration measured in the three different ecosystems, show the

  12. Study of the Quantum Efficiency of CsI Photocathodes Exposed to Oxygen and Water Vapour

    CERN Document Server

    Di Mauro, A; Piuz, François; Schyns, E M; Van Beelen, J B; Williams, T D

    2000-01-01

    The operation of CsI photocathodes in gaseous detectors requires special attention to the purity of the applied gas mixtures.We have studied the influence of oxygen and water vapour contaminations on the performance of CsI photocathodes for theALICE HMPID RICH prototype. Measurements were done through comparison of Cherenkov rings obtained from beamtests. Increased levels of oxygen and water vapour did not show any effect on the performance. The results of this studyfound a direct application in the way of storing CsI photocathodes over long periods nad in particular in the shipment of theHMPID prototype from CERN to the STAR experiment at BNL. (Abstract only available,full text to follow)

  13. The influence of heat pre-treatment on the sorption of water vapour on bentonite

    Czech Academy of Sciences Publication Activity Database

    Mokrejš, P.; Zikánová, Arlette; Hradil, David; Štulík, K.; Pacáková, V.; Kočiřík, Milan; Eić, M.

    2005-01-01

    Roč. 11, č. 1 (2005), s. 57-63 ISSN 0929-5607 R&D Projects: GA ČR(CZ) GA104/02/1464; GA MŠk(CZ) LN00A028 Institutional research plan: CEZ:AV0Z40400503 Keywords : adsorption * bentonite * montmorillonite * water vapour Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.323, year: 2005

  14. Influence of sea ice cover on evaporation and water vapour isotopic composition in the Arctic

    Science.gov (United States)

    Bonne, Jean-Louis; Werner, Martin; Meyer, Hanno; Kipfstuhl, Sepp; Rabe, Benjamin; Behrens, Melanie; Schönicke, Lutz; Steen-Larsen, Hans Christian

    2017-04-01

    Since July 2015, water stable isotopes (HDO and H218O) have been measured at two Arctic facilities: during the summer on board of the research vessel Polarstern, and year-round at the Siberian coastal site of Samoylov, situated in the Lena delta (N 72°22', E 126°29'), close to the Laptev Sea. In both places, the isotopic composition of water vapour is analysed continuously in surface air. Additional isotopic measurements are performed on a daily basis in ocean surface water samples taken on Polarstern and on an event basis from precipitation sampled in Samoylov. The two Polarstern summer campaigns cover a large region of the western Artic Ocean, including a one-month campaign in the central and eastern Arctic crossing the North Pole in September 2015, with very cold conditions (up to -20°C). Combining ocean and atmospheric observations from Polarstern allows an evaluation of local surface water evaporation and its isotopic fingerprint relative to the oceanic and meteorological conditions as well as the partial sea ice cover. In the central and eastern Arctic, a large area of complete sea ice cover also revealed a strong impact on the advected moisture above the ice cap under very cold conditions. A first year of Siberian observations at Samoylov depicted a large seasonal variability, with extremely dry and isotopically depleted winter values. Contrasted seasonal isotopic regimes might be utilized for identifying moisture sources changes in the region, such as ocean surface closure by sea ice, or freezing of the Lena River. Besides documenting the present meteorology and changes in the Arctic, our measurements will contribute to a better interpretation of regional paleoclimate records based on water isotopes and to the evaluation of climate models in the Arctic. A first model-data comparison of our measurements with simulation results by the isotope-enabled atmospheric general circulation model ECHAM5-wiso have revealed relevant model biases in the Arctic realm.

  15. Remote sensing of water vapour profiles in the framework of the Total Carbon Column Observing Network (TCCON

    Directory of Open Access Journals (Sweden)

    M. Schneider

    2010-12-01

    Full Text Available We show that the near infrared solar absorption spectra recorded in the framework of the Total Carbon Column Observing Network (TCCON can be used to derive the vertical distribution of tropospheric water vapour. The resolution of the TCCON spectra of 0.02 cm−1 is sufficient for retrieving lower and middle/upper tropospheric water vapour concentrations with a vertical resolution of about 3 and 8 km, respectively. We document the good quality of the remotely-sensed profiles by comparisons with coincident in-situ Vaisala RS92 radiosonde measurements. Due to the high measurement frequency, the TCCON water vapour profile data offer novel opportunities for estimating the water vapour variability at different timescales and altitudes.

  16. A microwave satellite water vapour column retrieval for polar winter conditions

    Energy Technology Data Exchange (ETDEWEB)

    Perro, Christopher; Lesins, Glen; Duck, Thomas J.; Cadeddu, Maria

    2016-01-01

    A new microwave satellite water vapour retrieval for the polar winter atmosphere is presented. The retrieval builds on the work of Miao et al. (2001) and Melsheimer and Heygster (2008), employing auxiliary information for atmospheric conditions and numerical optimization. It was tested using simulated and actual measurements from the Microwave Humidity Sounder (MHS) satellite instruments. Ground truth was provided by the G-band vapour radiometer (GVR) at Barrow, Alaska. For water vapour columns less than 6 kg m-2, comparisons between the retrieval and GVR result in a root mean square (RMS) deviation of 0.39 kg m-2 and a systematic bias of 0.08 kg m-2. These results are compared with RMS deviations and biases at Barrow for the retrieval of Melsheimer and Heygster (2008), the AIRS and MIRS satellite data products, and the ERA-Interim, NCEP, JRA-55, and ASR reanalyses. When applied to MHS measurements, the new retrieval produces a smaller RMS deviation and bias than for the earlier retrieval and satellite data products. The RMS deviations for the new retrieval were comparable to those for the ERA-Interim, JRA-55, and ASR reanalyses; however, the MHS retrievals have much finer horizontal resolution (15 km at nadir) and reveal more structure. The new retrieval can be used to obtain pan-Arctic maps of water vapour columns of unprecedented quality. It may also be applied to measurements from the Special Sensor Microwave/Temperature 2 (SSM/T2), Advanced Microwave Sounding Unit B (AMSU-B), Special Sensor Microwave Imager/Sounder (SSMIS), Advanced Technology Microwave Sounder (ATMS), and Chinese MicroWave Humidity Sounder (MWHS) instruments.

  17. Parametric Reconstruction of Water Vapour Accumulation Modes in the Western and the Eastern Mediterranean Basins

    Science.gov (United States)

    Palau, J. L.; Rovira, F.; Millan, M.

    2009-09-01

    The Mediterranean Sea acts as a source of heat and moisture for the surrounding regions, but not only because it is a closed and warm sea. The Mediterranean Basin is located in the mid-latitudes (i.e., high solar insolation), and it is almost completely surrounded by mountains. Moreover, from a meteorological point of view, the Mediterranean Basin can be regarded as two well-differentiated sub-basins: The Western Mediterranean Basin, where the prevailing synoptic conditions are associated with the Azores High Pressure system; and the Eastern Mediterranean Basin, which is under the influence of the Middle-East monsoon low-pressure system. The combination of all these features enables strong evapotranspiration with lower ventilation conditions (especially on the Western side) than in other geographical areas of the world (e.g., areas under the direct influence of the Atlantic Ocean). As a result, there are different water vapour "accumulation modes” on both sides of the Mediterranean Basin. The determination of the main atmospheric accumulation modes and their seasonal variability on both sides of the Mediterranean Basin is a relevant issue for integrating some of the feedbacks driving climate change, e.g., precipitation regimes, secondary pollutant production, ventilation conditions, etc. This study focuses on the total water vapour accumulation modes found on both sides of the Mediterranean Basin throughout the year. The data used in this study come from the most recent EOS satellite missions. Specifically, this investigation analyses the nine-year time series of water vapour data measured by the MODIS instrument (MODerate Resolution Imaging Spectroradiometer) on board the TERRA (EOS AM-1) satellite. Annual evolution (2000-2008) and seasonality of the total precipitable water column are analysed in both the Western and the Eastern Mediterranean Basins. After carrying out the parametric reconstruction of the water vapour time series, we have obtained their

  18. Observed behaviours of precipitable water vapour and precipitation intensity in response to upper air profiles estimated from surface air temperature.

    Science.gov (United States)

    Fujita, Mikiko; Sato, Tomonori

    2017-07-06

    Extremely heavy precipitation affects human society and the natural environment, and its behaviour under a warming climate needs to be elucidated. Recent studies have demonstrated that observed extreme precipitation increases with surface air temperature (SAT) at approximately the Clausius-Clapeyron (CC) rate, suggesting that atmospheric water vapour content can explain the relationship between extreme precipitation and SAT. However, the relationship between atmospheric water vapour content and SAT is poorly understood due to the lack of reliable observations with sufficient spatial and temporal coverage for statistical analyses. Here, we analyse the relationship between atmospheric water vapour content and SAT using precipitable water vapour (PWV) derived from global positioning system satellites. A super-CC rate appears in hourly PWV when the SAT is below 16 °C, whereas the rate decreases at high SAT, which is different from the precipitation-SAT relationship. The effects of upper air temperature and water vapour can consistently explain the super-CC rate of PWV relative to SAT. The difference between moist and dry adiabatic lapse rates increases with SAT, in consequence of more ability to hold water vapour in the free atmosphere under higher SAT conditions; therefore, attainable PWV increases more rapidly than the CC rate as SAT increases.

  19. Tropospheric water vapour isotopologue data (H216O, H218O, and HD16O) as obtained from NDACC/FTIR solar absorption spectra

    Science.gov (United States)

    Barthlott, Sabine; Schneider, Matthias; Hase, Frank; Blumenstock, Thomas; Kiel, Matthäus; Dubravica, Darko; García, Omaira E.; Sepúlveda, Eliezer; Mengistu Tsidu, Gizaw; Takele Kenea, Samuel; Grutter, Michel; Plaza-Medina, Eddy F.; Stremme, Wolfgang; Strong, Kim; Weaver, Dan; Palm, Mathias; Warneke, Thorsten; Notholt, Justus; Mahieu, Emmanuel; Servais, Christian; Jones, Nicholas; Griffith, David W. T.; Smale, Dan; Robinson, John

    2017-01-01

    We report on the ground-based FTIR (Fourier transform infrared) tropospheric water vapour isotopologue remote sensing data that have been recently made available via the database of NDACC (Network for the Detection of Atmospheric Composition Change; MUSICA/" target="_blank">ftp://ftp.cpc.ncep.noaa.gov/ndacc/MUSICA/) and via doi:10.5281/zenodo.48902. Currently, data are available for 12 globally distributed stations. They have been centrally retrieved and quality-filtered in the framework of the MUSICA project (MUlti-platform remote Sensing of Isotopologues for investigating the Cycle of Atmospheric water). We explain particularities of retrieving the water vapour isotopologue state (vertical distribution of H216O, H218O, and HD16O) and reveal the need for a new metadata template for archiving FTIR isotopologue data. We describe the format of different data components and give recommendations for correct data usage. Data are provided as two data types. The first type is best-suited for tropospheric water vapour distribution studies disregarding different isotopologues (comparison with radiosonde data, analyses of water vapour variability and trends, etc.). The second type is needed for analysing moisture pathways by means of H2O, δD-pair distributions.

  20. Analysis of long time series of precipitable water vapour from GPS, DORIS and NWP models

    Science.gov (United States)

    Bock, Olivier; Willis, Pascal

    2013-04-01

    The analysis of GPS and DORIS measurements provides accurate estimates of zenith tropospheric delay (ZTD) and total column water vapour (TCWV). Such measurements are now available for more than 15 years from permanent ground-based stations which cover quite homogenously the globe and receive increasing interest for meteorology and climate research. This work assesses the quality of operational and reprocessed GPS and DORIS datasets. Regarding GPS, two solutions produced by JPL as contributions to IGS (repro1, covering period 1995-2007, and trop_new, covering period 2001-2010) are compared. An independent reprocessed solution produced by IGN (sgn_repro1, covering period 2004-2010) is also used in the intercomparison. Differences due to different data processing procedures and errors in metadata and discontinuities due to changes in data processing procedures are evidenced in the operational solution. A reprocessed DORIS solution (IGN solution, period 1993-2008) is also compared to GPS and to the ECMWF reanalysis (ERA-Interim). The impact of changes in GPS or DORIS equipment on the quality of the ZTD estimates is investigated. The reprocessed GPS and DORIS ZTD estimates are converted into TCWV and analysed globally and for different regions. The TCWV time series reveal significant variability at various timescales (inter-annual, seasonal, intra-seasonal and synoptic) and look very promising for validating independent observational datasets (e.g., radiosondes and satellite products) and models (reanalyses, climate models).

  1. Efficient quantification of water content in edible oils by headspace gas chromatography with vapour phase calibration.

    Science.gov (United States)

    Xie, Wei-Qi; Gong, Yi-Xian; Yu, Kong-Xian

    2017-11-24

    An automated and accurate headspace gas chromatographic (HS-GC) technique was investigated for rapidly quantifying water content in edible oils. In this method, multiple headspace extraction (MHE) procedures were used to analyse the integrated water content from the edible oil sample. A simple vapour phase calibration technique with an external vapour standard was used to calibrate both the water content in the gas phase and the total weight of water in edible oil sample. After that the water in edible oils can be quantified. The data showed that the relative standard deviation of the present HS-GC method in the precision test was less than 1.13%, the relative differences between the new method and a reference method (i.e. the oven-drying method) were no more than 1.62%. The present HS-GC method is automated, accurate, efficient, and can be a reliable tool for quantifying water content in edible oil related products and research. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

  2. Stratospheric water vapour budget and convection overshooting the tropopause: modelling study from SCOUT-AMMA

    Directory of Open Access Journals (Sweden)

    X. M. Liu

    2010-09-01

    Full Text Available The aim of this paper is to study the impacts of overshooting convection at a local scale on the water distribution in the tropical UTLS. Overshooting convection is assumed to be one of the processes controlling the entry of water vapour mixing ratio in the stratosphere by injecting ice crystals above the tropopause which later sublimate and hydrate the lower stratosphere. For this purpose, we quantify the individual impact of two cases of overshooting convection in Africa observed during SCOUT-AMMA: the case of 4 August 2006 over Southern Chad which is likely to have influenced the water vapour measurements by micro-SDLA and FLASH-B from Niamey on 5 August, and the case of a mesoscale convective system over Aïr on 5 August 2006. We make use of high resolution (down to 1 km horizontally nested grid simulations with the three-dimensional regional atmospheric model BRAMS (Brazilian Regional Atmospheric Modelling System. In both cases, BRAMS succeeds in simulating the main features of the convective activity, as well as overshooting convection, though the exact position and time of the overshoots indicated by MSG brightness temperature difference is not fully reproduced (typically 1° displacement in latitude compared with the overshoots indicated by brightness temperature difference from satellite observations for both cases, and several hours shift for the Aïr case on 5 August 2006. Total water budgets associated with these two events show a significant injection of ice particles above the tropopause with maximum values of about 3.7 ton s−1 for the Chad case (4 August and 1.4 ton s−1 for the Aïr case (5 August, and a total upward cross tropopause transport of about 3300 ton h−1 for the Chad case and 2400 ton h−1 for the Aïr case in the third domain of simulation. The order of magnitude of these modelled fluxes is lower but comparable with similar studies in other tropical areas based on

  3. Lidar observations of low-level wind reversals over the Gulf of Lion and characterization of their impact on the water vapour variability

    Science.gov (United States)

    Di Girolamo, Paolo; Flamant, Cyrille; Cacciani, Marco; Summa, Donato; Stelitano, Dario; Richard, Evelyne; Ducrocq, Véronique; Fourrie, Nadia; Said, Frédérique

    2017-02-01

    Water vapour measurements from a ground-based Raman lidar and an airborne differential absorption lidar, complemented by high resolution numerical simulations from two mesoscale models (Arome-WMED and MESO-NH), are considered to investigate transition events from Mistral/Tramontane to southerly marine flow taking place over the Gulf of Lion in Southern France in the time frame September-October 2012, during the Hydrological Cycle in the Mediterranean Experiment (HyMeX) Special Observation Period 1 (SOP1). Low-level wind reversals associated with these transitions are found to have a strong impact on water vapour transport, leading to a large variability of the water vapour vertical and horizontal distribution. The high spatial and temporal resolution of the lidar data allow to monitor the time evolution of the three-dimensional water vapour field during these transitions from predominantly northerly Mistral/Tramontane flow to a predominantly southerly flow, allowing to identify the quite sharp separation between these flows, which is also quite well captured by the mesoscale models.

  4. Lidar Observations of Low-level Wind Reversals over the Gulf of Lion and Characterization of Their Impact on the Water Vapour Variability

    Directory of Open Access Journals (Sweden)

    Di Girolamo Paolo

    2016-01-01

    Full Text Available Water vapour measurements from a ground-based Raman lidar and an airborne differential absorption lidar, complemented by high resolution numerical simulations from two mesoscale models (Arome-WMED and MESO-NH, are considered to investigate transition events from Mistral/Tramontane to southerly marine flow taking place over the Gulf of Lion in Southern France in the time frame September-October 2012, during the Hydrological Cycle in the Mediterranean Experiment (HyMeX Special Observation Period 1 (SOP1. Low-level wind reversals associated with these transitions are found to have a strong impact on water vapour transport, leading to a large variability of the water vapour vertical and horizontal distribution. The high spatial and temporal resolution of the lidar data allow to monitor the time evolution of the three-dimensional water vapour field during these transitions from predominantly northerly Mistral/Tramontane flow to a predominantly southerly flow, allowing to identify the quite sharp separation between these flows, which is also quite well captured by the mesoscale models.

  5. Water vapour and hydrogen in the terrestrial-planet-forming region of a protoplanetary disk.

    Science.gov (United States)

    Eisner, J A

    2007-05-31

    Planetary systems (ours included) formed in disks of dust and gas around young stars. Disks are an integral part of the star and planet formation process, and knowledge of the distribution and temperature of inner-disk material is crucial for understanding terrestrial planet formation, giant planet migration, and accretion onto the central star. Although the inner regions of protoplanetary disks in nearby star-forming regions subtend only a few nano-radians, near-infrared interferometry has recently enabled the spatial resolution of these terrestrial zones. Most observations have probed only dust, which typically dominates the near-infrared emission. Here I report spectrally dispersed near-infrared interferometric observations that probe the gas (which dominates the mass and dynamics of the inner disk), in addition to the dust, within one astronomical unit (1 au, the Sun-Earth distance) of the young star MWC 480. I resolve gas, including water vapour and atomic hydrogen, interior to the edge of the dust disk; this contrasts with results of previous spectrally dispersed interferometry observations. Interactions of this accreting gas with migrating planets may lead to short-period exoplanets like those detected around main-sequence stars. The observed water vapour is probably produced by the sublimation of migrating icy bodies, and provides a potential reservoir of water for terrestrial planets.

  6. Airborne hygrometer calibration inter-comparison against a metrological water vapour standard

    Science.gov (United States)

    Smorgon, Denis; Boese, Norbert; Ebert, Volker

    2014-05-01

    Water vapour is the most important atmospheric greenhouse gas, which causes a major feedback to warming and other changes in the climate system. Knowledge of the distribution of water vapour and its climate induced changes is especially important in the upper troposphere and lower stratosphere (UT/LS) where vapour plays a critical role in atmospheric radiative balance, cirrus cloud formation, and photochemistry. But, our understanding of water in the UT/LS is limited by significant uncertainties in current UT/LS water measurements. One of the most comprehensive inter-comparison campaigns for airborne hygrometers, termed AQUAVIT (AV1) [1], took place in 2007 at the AIDA chamber at the Karlsruhe Institute of Technology (KIT) in Germany. AV1 was a well-defined, referred, blind inter-comparison of 22 airborne field instruments from 17 international research groups. One major metrological deficit of AV1, however, was, that no traceable reference instrument participated in the inter-comparison experiments and that the calibration procedures of the participating instruments were not monitored or interrogated. Consequently a follow-up inter-comparison was organized in April 2013, which for the first time also provides a traceable link to the international humidity scale. This AQUAVIT2 (AV2) campaign (details see: http://www.imk-aaf.kit.edu/aquavit/index.php/Main_Page) was again located at KIT/AIDA and organised by an international organizing committee including KIT, PTB, FZJ and others. Generally AV2 is divided in two parallel comparisons: 1) AV2-A uses the AIDA chamber for a simultaneous comparison of all instruments (incl. sampling and in-situ instruments) over a broad range of conditions characteristic for the UT/LS; 2) AV2-B, about which this paper is reporting, is a sequential comparison of selected hygrometers and (when possible) their reference calibration infrastructures by means of a chilled mirror hygrometer traced back to the primary National humidity standard

  7. Swelling behaviour of Early Jurassic shales when exposed to water vapour

    Science.gov (United States)

    Houben, Maartje; Barnhoorn, Auke; Peach, Colin; Drury, Martyn

    2017-04-01

    The presence of water in mudrocks has a largely negative impact on production of gas, due to the fact that water causes swelling of the rock. Removing the water from the mudrock on the other hand could potentially shrink the rock and increase the matrix permeability. Investigation of the swelling/shrinkage behaviour of the rock during exposure to water vapour is of key importance in designing and optimizing unconventional production strategies. We have used outcrop samples of the Whitby Mudstone and the Posidonia shale [1], potential unconventional sources for gas in North-western Europe, to measure the swelling and shrinkage behaviour. Subsamples, 1 mm cubes, were prepared by the Glass Workshop at Utrecht University using a high precision digitally controlled diamond wafering saw cooled by air. The mm cubes were then exposed to atmospheres with different relative humidities either in an Environmental Scanning Electron Microscope (ESEM) or in a 3D dilatometer. So that the sample responses to exposure of water vapour could be measured. Parallel to the bedding we found a swelling strain between 0.5 and 1.5 %, perpendicular to the bedding though swelling strain varied between 1 and 3.5%. Volumetric swelling strain varied between 1 and 2% at a maximum relative humidity of 95%. Volumetric swelling strains measured in the Early Toarcian Shales are similar to the ones found in coal [2], where the results suggest that it might be possible to increase permeability in the reservoir by decreasing the in-situ water activity due to shrinkage of the matrix. [1] M.E. Houben, A. Barnhoorn, L. Wasch, J. Trabucho-Alexandre, C. J. Peach, M.R. Drury (2016). Microstructures of Early Jurassic (Toarcian) shales of Northern Europe, International Journal of Coal Geology, 165, 76-89. [2] Jinfeng Liu, Colin J. Peach, Christopher J. Spiers (2016). Anisotropic swelling behaviour of coal matrix cubes exposed to water vapour: Effects of relative humidity and sample size, International Journal of

  8. The H2O-O2 water vapour complex in the Earth's atmosphere

    Directory of Open Access Journals (Sweden)

    S. Kondo

    2011-08-01

    Full Text Available Until recently, abundance estimates for bound molecular complexes have been affected by uncertainties of a factor 10–100. This is due to the difficulty of accurately obtaining the equilibrium constant, either from laboratory experiments or by statistical thermodynamic calculations. In this paper, we firstly present laboratory experiments that we performed in order to determine the molecular structure of H2O-O2. We also derive global abundance estimates for H2O-O2 in the Earth's atmosphere. The equilibrium constant Kp evaluated using the "anharmonic oscillator approach" (AHOA (Sabu et al., 2005 was employed: the AHOA explains well the structure of the complex obtained by the present experiment. The Kp calculated by this method shows a realistic temperature dependence. We used this Kp to derive global abundance estimates for H2O-O2 in the Earth's atmosphere. The distribution of H2-O2 follows that of water vapour in the troposphere and seems inversely proportional to temperature in the lower stratosphere. Preliminary estimates at the surface show amount of H2O-O2 is comparable to CO or N2O, ranking water vapour complexes among the ten most abundant species in the boundary layer.

  9. A model study on the influence of overshooting convection on TTL water vapour

    Directory of Open Access Journals (Sweden)

    M. E. E. Hassim

    2010-10-01

    Full Text Available Overshooting deep convection that penetrates into the Tropical Tropopause Layer (TTL is thought to have an important role in regulating the water vapour content of this region. Yet, the net effect of such convection and the dominant mechanisms remain unclear. This study uses two idealised three-dimensional cloud-resolving model simulations to examine the influence of overshooting convection on water vapour when it penetrates into two different TTL environments, one supersaturated and the other subsaturated with respect to ice. These simulations show that the overshooting convection plays a direct role in driving the ambient environment towards ice saturation through either net moistening (subsaturated TTL or net dehydration (supersaturated TTL. Moreover, in these cases the extent of dehydration in supersaturated conditions is greater than the moistening in subsaturated conditions. With the aid of modelled passive tracers, the relative roles of transport, mixing and ice microphysics are assessed; ultimately, ice sublimation and scavenging processes play the most important role in defining the different TTL relative humidity tendencies. In addition, significant moistening in both cases is modelled well into the subsaturated tropical lower stratosphere (up to 450 K, even though the overshooting turrets only reach approximately 420 K. It is shown that this moistening is the result of jumping cirrus, which is induced by the localised upward transport and mixing of TTL air following the collapse of the overshooting turret.

  10. The influence of moisture content on the water vapour resistance of surface coated spruce

    DEFF Research Database (Denmark)

    Engelund, E.T.; Ulriksen, L.; Hansen, Kurt Kielsgaard

    2005-01-01

    Two series of cup tests are carried out. The first series is performed on spruce specimens having moisture transport in either radial direction (R-direction) or in tangential direction (T-direction). The T-direction tests are made as wet cup tests having 93 %RH inside the cups, while the R......, but now with one layer of paint (60 g/m^2) on one surface of the wood specimens. The results show that the RH level significantly influences the water vapour resistance of the paint. For wet cup tests a water vapour resistance of the paint of 6.5•10^8 Pa•m^2•s/kg in average is found. In contrast......-direction tests are made as dry cup tests having 33 %RH in the cups. The RH in the outside climate is 60 % for both R- and T-direction. The temperature during the tests is 23 degree C. The second cup test series is performed on the same spruce specimens and at the same climatic conditions as in the first series...

  11. Water vapour source impacts on oxygen isotope variability in tropical precipitation during Heinrich events

    Directory of Open Access Journals (Sweden)

    S. C. Lewis

    2010-06-01

    Full Text Available Water isotope records such as speleothems provide extensive evidence of past tropical hydrological changes. During Heinrich events, isotopic changes in monsoon regions have been interpreted as implying a widespread drying through the Northern Hemisphere tropics and an anti-phased precipitation response in the south. Here, we examine the sources of this variability using a water isotope-enabled general circulation model, Goddard Institute for Space Studies ModelE. We incorporate a new suite of vapour source distribution tracers to help constrain the impact of precipitation source region changes on the isotopic composition of precipitation and to identify nonlocal amount effects. We simulate a collapse of the North Atlantic meridional overturning circulation with a large freshwater input to the region as an idealised analogue to iceberg discharge during Heinrich events. An increase in monsoon intensity, defined by vertical wind shear, is modelled over the South American domain, with small decreases simulated over Asia. Simulated isotopic anomalies agree well with proxy climate records, with lighter isotopic values simulated over South America and enriched values across East Asia. For this particular abrupt climate event, we identify which climatic change is most likely linked to water isotope change – changes in local precipitation amount, monsoon intensity, water vapour source distributions or precipitation seasonality. We categorise individual sites according to the climate variability that water isotope changes are most closely associated with, and find that the dominant isotopic controls are not consistent across the tropics – simple local explanations, in particular, fall short of explaining water isotope variability at all sites. Instead, the best interpretations appear to be site specific and often regional in scale.

  12. Oxidation of X20 in Water Vapour: The Effect of Temperature and Oxygen Partial Pressure

    DEFF Research Database (Denmark)

    Hansson, Anette Nørgaard; Montgomery, Melanie; Somers, Marcel A. J.

    2009-01-01

    The oxidation behaviour of X20 in various mixtures of water, oxygen and hydrogen was investigated at temperatures between 500 C and 700 C (time: 336 h). The samples were characterised using reflected light microscopy and scanning electron microscopy equipped with energy dispersive spectroscopy....... Double-layered oxides developed during oxidation under all conditions. The morphology of the oxide layers was strongly influenced by temperature, whereas the influence of the oxidising environment appeared to be less pronounced, as long as it contained water vapour. The inner layer consisted of converted...... M23C6 embedded in Fe–Cr spinel after oxidation at 500 and 600 C, while alternating layers of Cr-rich and Cr-poor oxide were observed after oxidation at 700 C. An internal oxidation zone developed during oxidation at 500 and 600 C, with its depth influenced by the oxidising environments. The results...

  13. Strong low-pass filtering effects on water vapour flux measurements with closed-path eddy correlation systems

    DEFF Research Database (Denmark)

    Ibrom, Andreas; Dellwik, Ebba; Flyvbjerg, Henrik K.

    2007-01-01

    concentration measurements decreases exponentially with increasing relative humidity. After correction for this unintended filtering, the fluxes are consistent with CO2 and H2O fluxes that were measured with an open-path sensor at the same time. The correction of water vapour flux measurements over a Beech......-pass filtering effects. Other than for CO2 is the magnitude of the correction for water vapour flux measurements unsatisfactorily high, i.e. the EC system needs to be technically improved. Our results suggest that such high correction can be avoided by keeping relative humidity in the entire gas transport system...

  14. An energy balance model exploration of the impacts of interactions between surface albedo, water vapour and clouds on polar amplification

    Science.gov (United States)

    Sodergren, Helena; McDonald, Adrian; Bodeker, Greg

    2017-04-01

    The interactions between surface albedo, water vapour and clouds, and how these interactions change with carbon dioxide (CO2) concentrations in the atmosphere, are examined with a newly developed energy balance model. A particular focus is the non-linear interactions of these climate system attributes on polar amplification. Polar amplification is defined here as the ratio of the annual rate of surface warming over the polar regions (latitudes poleward of 60o) to the surface warming over equatorial regions (latitudes equatorward of 30o), and is termed the polar amplification factor. Changes in surface albedo plays a major role in polar amplification as might be expected, due to its amplifying effects of CO2 -induced warming of the polar regions, and relatively small warming effects in the equatorial regions. When considered in isolation from the other climate system components, i.e. when water vapour and cloud cover are prescribed, changes in surface albedo result in a polar amplification factor of 4.83 for a doubling of CO2, compared to 5.54 for the full feedback simulation, i.e. the simulation where all three components are allowed to simultaneously change with temperature. In our simple model framework, changes in surface albedo are responsible for 43% of the polar warming from the full feedback run, and 49% of the equatorial warming. The polar amplification for the simulation with isolated climate feedback from cloud cover variations is smaller than the simulation with isolated surface albedo feedback, mainly due to a weaker warming in the polar regions. The polar amplification factor for the isolated cloud cover feedback simulation is 3.73, contributing 30% of the warming in the polar regions to the full feedback simulation and 45% in the equatorial regions. The amplifying effect from changing surface albedo on polar warming and polar amplification is enhanced when surface albedo interacts with cloud cover or water vapour. The polar amplification factor is

  15. Trends and variability of midlatitude stratospheric water vapour deduced from the re-evaluated Boulder balloon series and HALOE

    Directory of Open Access Journals (Sweden)

    M. Scherer

    2008-03-01

    Full Text Available This paper presents an updated trend analysis of water vapour in the lower midlatitude stratosphere from the Boulder balloon-borne NOAA frostpoint hygrometer measurements and from the Halogen Occulation Experiment (HALOE. Two corrections for instrumental bias are applied to homogenise the frostpoint data series, and a quality assessment of all soundings after 1991 is presented. Linear trend estimates based on the corrected data for the period 1980–2000 are up to 40% lower than previously reported. Vertically resolved trends and variability are calculated with a multi regression analysis including the quasi-biennal oscillation and equivalent latitude as explanatory variables. In the range of 380 to 640 K potential temperature (≈14 to 25 km, the frostpoint data from 1981 to 2006 show positive linear trends between 0.3±0.3 and 0.7±0.1%/yr. The same dataset shows trends between −0.2±0.3 and 1.0±0.3%/yr for the period 1992 to 2005. HALOE data over the same time period suggest negative trends ranging from −1.1±0.2 to −0.1±0.1%/yr. In the lower stratosphere, a rapid drop of water vapour is observed in 2000/2001 with little change since. At higher altitudes, the transition is more gradual, with slowly decreasing concentrations between 2001 and 2007. This pattern is consistent with a change induced by a drop of water concentrations at entry into the stratosphere. Previously noted differences in trends and variability between frostpoint and HALOE remain for the homogenised data. Due to uncertainties in reanalysis temperatures and stratospheric transport combined with uncertainties in observations, no quantitative inference about changes of water entering the stratosphere in the tropics could be made with the mid latitude measurements analysed here.

  16. Developing a western Siberia reference site for tropospheric water vapour isotopologue observations obtained by different techniques (in situ and remote sensing

    Directory of Open Access Journals (Sweden)

    K. Gribanov

    2014-06-01

    water cycle, affected by changes in air mass origin, non-convective and convective processes and continental recycling. Novel remote sensing and in situ measuring techniques have recently offered opportunities for monitoring atmospheric water vapour isotopic composition. Recently developed infrared laser spectrometers allow for continuous in situ measurements of surface water vapour δDv and δ18Ov. So far, very few intercomparisons of measurements conducted using different techniques have been achieved at a given location, due to difficulties intrinsic to the comparison of integrated with local measurements. Nudged simulations conducted with high-resolution isotopically enabled general circulation models (GCMs provide a consistent framework for comparison with the different types of observations. Here, we compare simulations conducted with the ECHAM5-wiso model with two types of water vapour isotopic data obtained during summer 2012 at the forest site of Kourovka, western Siberia: hourly ground-based FTIR total atmospheric columnar δDv amounts, and in situ hourly Picarro δDv measurements. There is an excellent correlation between observed and predicted δDv at surface while the comparison between water column values derived from the model compares well with FTIR estimates.

  17. Evolution of stratospheric ozone and water vapour time series studied with satellite measurements

    Directory of Open Access Journals (Sweden)

    A. Jones

    2009-08-01

    Full Text Available The long term evolution of stratospheric ozone and water vapour has been investigated by extending satellite time series to April 2008. For ozone, we examine monthly average ozone values from various satellite data sets for nine latitude and altitude bins covering 60° S to 60° N and 20–45 km and covering the time period of 1979–2008. Data are from the Stratospheric Aerosol and Gas Experiment (SAGE I+II, the HALogen Occultation Experiment (HALOE, the Solar BackscatterUltraViolet-2 (SBUV/2 instrument, the Sub-Millimetre Radiometer (SMR, the Optical Spectrograph InfraRed Imager System (OSIRIS, and the SCanning Imaging Absorption spectroMeter for Atmospheric CHartograpY (SCIAMACHY. Monthly ozone anomalies are calculated by utilising a linear regression model, which also models the solar, quasi-biennial oscillation (QBO, and seasonal cycle contributions. Individual instrument ozone anomalies are combined producing an all instrument average. Assuming a turning point of 1997 and that the all instrument average is represented by good instrumental long term stability, the largest statistically significant ozone declines (at two sigma from 1979–1997 are seen at the mid-latitudes between 35 and 45 km, namely −7.2%±0.9%/decade in the Northern Hemisphere and −7.1%±0.9%/in the Southern Hemisphere. Furthermore, for the period 1997 to 2008 we find that the same locations show the largest ozone recovery (+1.4% and +0.8%/decade respectively compared to other global regions, although the estimated trend model errors indicate that the trend estimates are not significantly different from a zero trend at the 2 sigma level. An all instrument average is also constructed from water vapour anomalies during 1991–2008, using the SAGE II, HALOE, SMR, and the Microwave Limb Sounder (Aura/MLS measurements. We report that the decrease in water vapour values after 2001 slows down around 2004–2005 in the lower tropical stratosphere (20–25 km and has even

  18. Applicability of the Guggenheim–Anderson–Boer water vapour sorption model for estimation of soil specific surface area

    DEFF Research Database (Denmark)

    Arthur, Emmanuel; Tuller, Markus; Møldrup, Per

    2018-01-01

    -based modelling approaches to determine SA. Measured water vapour adsorption and desorption isotherms for 321 soil samples were used to parameterize the GAB model, the Brunauer–Emmet–Teller (BET) equation and a film adsorption Tuller–Or (TO) model to estimate SA. For adsorption isotherms, the values of the GAB...... compared with SA measured by the ethylene glycol monoethyl ether (EGME) method. For kaolinitic samples, however, the BET equation provided the best estimate of EGME-SA. The SA estimates of the GAB model were comparable to those obtained by the TO adsorption model. Thus, the GAB model provides a good...... alternative to the TO model (applicable only to adsorption data) or the BET model, which fails when the fraction of swelling clay minerals increases....

  19. A review on the recent development of solar absorption and vapour compression based hybrid air conditioning with low temperature storage

    Directory of Open Access Journals (Sweden)

    Noor D. N.

    2016-01-01

    Full Text Available Conventional air conditioners or vapour compression systems are main contributors to energy consumption in modern buildings. There are common environmental issues emanating from vapour compression system such as greenhouse gas emission and heat wastage. These problems can be reduced by adaptation of solar energy components to vapour compression system. However, intermittence input of daily solar radiation was the main issue of solar energy system. This paper presents the recent studies on hybrid air conditioning system. In addition, the basic vapour compression system and components involved in the solar air conditioning system are discussed. Introduction of low temperature storage can be an interactive solution and improved economically which portray different modes of operating strategies. Yet, very few studies have examined on optimal operating strategies of the hybrid system. Finally, the findings of this review will help suggest optimization of solar absorption and vapour compression based hybrid air conditioning system for future work while considering both economic and environmental factors.

  20. Renovation and design of double casement windows with regard to the occurrence of water vapour condensation or mould on the interior surface of the window jamb

    Science.gov (United States)

    Kudrnacova, L.; Balik, L.

    2017-10-01

    The condensation of water vapour on the interior surface is an indicator of construction dysfunction or ignoring of the surroundings temperature and relative humidity. This paper deals with analysis of the occurrence of condensation on the jamb of double casement windows (windows with two window casements). More precisely, this is a surface in the interior where water vapour condensation or mould occur. For the renovation of existing double casement windows, there are different solutions based on window design: application of double insulating glazing on the interior window casement, application of double insulating glazing on the exterior casement, or installation of a simple window. We first describe measurement of an existing double casement window located in a mountain cottage. Second, the results and comparison of 2D thermal model of different types of double casement window construction. Also, the external insulation of the peripheral wall was included in the model.

  1. Influence of water vapour and permanent gases on the atmospheric optical depths and transmittance

    Science.gov (United States)

    Badescu, V.

    1991-05-01

    The influence of the atmospheric state on the extinction of direct solar radiation has been studied by using a four layer atmospheric model. Simple analytical formulae are established for the spectral optical depths of permanent gases and water vapour. These formulae use the ground level values of air pressure, temperature and relative huniidity. An additional parameter, related to the vertical distribution of the hunmidity content, is used for a better estimation of the water vapour optical depth. Good agreement between theory and measurements is found. The paper shows the dependence of the atmospheric spectral transmittance on the above mentioned parameters. L'influence de l'état atmosphérique sur l'extinction de la radiation solaire directe a été étudiée à l'aide d'un modèle atmosphérique développé antérieurement par l'auteur. Des formules simples ont été établies pour l'épaisseur optique spectrale des gaz et de la vapeur d'eau. Ces formules utilisent les valeurs de la pression atmosphérique, de la température et de l'humidité relative, mesurées au niveau du sol. Un paramètre supplémentaire, lié à la distribution verticale du contenu d'humidité, est utilisé pour calculer l'épaisseur optique due à la vapeur d'eau. La théorie est en bon accord avec les résultats des mesures. Le travail montre la dépendance de la transmittance atmosphérique spectrale en fonction des paramètres spécifiés ci-dessus.

  2. Enhanced MODIS Atmospheric Total Water Vapour Content Trends in Response to Arctic Amplification

    Directory of Open Access Journals (Sweden)

    Dunya Alraddawi

    2017-12-01

    Full Text Available In order to assess the strength of the water vapour feedback within Arctic climate change, 15 years of the total column-integrated density of water vapour (TCWV from the moderate resolution imaging spectrometer (MODIS are analysed. Arctic TCWV distribution, trends, and anomalies for the 2001–2015 period, broken down into seasons and months, are analysed. Enhanced local spring TCWV trends above the terrestrial Arctic regions are discussed in relation to land snow cover and vegetation changes. Upward TCWV trends above the oceanic areas are discussed in lien with sea ice extent and sea surface temperature changes. Increased winter TCWV (up to 40% south of the Svalbard archipelago are observed; these trends are probably driven by a local warming and sea ice extent decline. Similarly, the Barents/Kara regions underwent wet trends (up to 40%, also associated with winter/fall local sea ice loss. Positive late summer TCWV trends above the western Greenland and Beaufort seas (about 20% result from enhanced upper ocean warming and thereby a local coastal decline in ice extent. The Mackenzie and Siberia enhanced TCWV trends (about 25% during spring are found to be associated with coincident decreased snow cover and increased vegetation, as a result of the earlier melt onset. Results show drier summers in the Eurasia and western Alaska regions, thought to be affected by changes in albedo from changing vegetation. Other TCWV anomalies are also presented and discussed in relation to the dramatic decline in sea ice extent and the exceptional rise in sea surface temperature.

  3. On the importance of proper noise modelling for long-term precipitable water vapour trend estimations

    Energy Technology Data Exchange (ETDEWEB)

    Combrink, A.Z.A. [Hartebeesthoek Radio Astronomy Observatory, Krugersdorp (South Africa). Space Geodesy Programme]|[Univ. of Cape town, Rondebosch (South Africa). School of Architecture, Planning and Geomatics; Bos, M.S. [Univ. do Porto, do Campo Alegre (Portugal); Fernandes, R.M.S. [IDL, Covilha (Portugal)]|[Delft Univ. of Technology (Netherlands); Combrinck, W.L.; Combrinck, W.L. [Hartebeesthoek Radio Astronomy Observatory, Krugersdorp (South Africa). Space Geodesy Programme; Merry, C.L. [Univ. of Cape Town, Rondebosch (South Africa). School of Architecture, Planning and Geomatics

    2007-09-15

    Time-series of precipitable water vapour (PWV), derived from continuous Global Positioning System (GPS) observations, are analyzed for the two South African stations HRAO and SUTH. Since water vapour is a major greenhouse gas, observed changes in atmospheric PWV could be indicative of weather and climate change. The authors' main contribution is a realistic noise model of the PWV observations which enables one to draw correct conclusions about the significance of the derived PWV increase or decrease for given time spans longer than five years. It is demonstrated that the PWV residuals that are obtained after fitting a trend and yearly signal to the data are, due to the simple model's exclusion of short-term scatter, much larger than the PWV uncertainties provided by the GPS analysis software. Although a better solution for the associated uncertainties is obtained by using the variance of these PWV residuals for the uncertainty rescaling, it is shown that the ARMA(1,1) noise model better represents the associated statistical uncertainties than the simple white noise model. The ARMA(1,1)-derived PWV trend uncertainties are approximately 2 times greater than those for a rescaled white noise model. Finally, it is argued that the variability of the annual signal prevents any trend estimation using time series shorter than about five years. A quantitative measure is presented to determine the minimum period of continuous GPS observational data required to measure PWV trends to a specified accuracy. As a result of the study, the authors conclude that no statistically significant PWV trends are observed at the two GPS stations between 1998 and 2006.

  4. Technical Note: Novel method for water vapour monitoring using wireless communication networks measurements

    Directory of Open Access Journals (Sweden)

    N. David

    2009-04-01

    Full Text Available We propose a new technique that overcomes the obstacles of the existing methods for monitoring near-surface water vapour, by estimating humidity from data collected through existing wireless communication networks.

    Weather conditions and atmospheric phenomena affect the electromagnetic channel, causing attenuations to the radio signals. Thus, wireless communication networks are in effect built-in environmental monitoring facilities. The wireless microwave links, used in these networks, are widely deployed by cellular providers for backhaul communication between base stations, a few tens of meters above ground level. As a result, if all available measurements are used, the proposed method can provide moisture observations with high spatial resolution and potentially high temporal resolution. Further, the implementation cost is minimal, since the data used are already collected and saved by the cellular operators. In addition – many of these links are installed in areas where access is difficult such as orographic terrain and complex topography. As such, our method enables measurements in places that have been hard to measure in the past, or have never been measured before. The technique is restricted to weather conditions which exclude rain, fog or clouds along the propagation path. Strong winds that may cause movement of the link transmitter or receiver (or both may also interfere with the ability to conduct accurate measurements.

    We present results from real-data measurements taken from two microwave links used in a backhaul cellular network that show convincing correlation to surface station humidity measurements. The measurements were taken daily in two sites, one in northern Israel (28 measurements, the other in central Israel (29 measurements. The correlation between the microwave link measurements and the humidity gauges were 0.9 and 0.82 for the north and central sites, respectively. The Root Mean Square Differences

  5. Soil-water characteristics of Gaomiaozi bentonite by vapour equilibrium technique

    Directory of Open Access Journals (Sweden)

    Wenjing Sun

    2014-02-01

    Full Text Available Soil-water characteristics of Gaomiaozi (GMZ Ca-bentonite at high suctions (3–287 MPa are measured by vapour equilibrium technique. The soil-water retention curve (SWRC of samples with the same initial compaction states is obtained in drying and wetting process. At high suctions, the hysteresis behaviour is not obvious in relationship between water content and suction, while the opposite holds between degree of saturation and suction. The suction variation can change its water retention behaviour and void ratio. Moreover, changes of void ratio can bring about changes in degree of saturation. Therefore, the total change in degree of saturation includes changes caused by suction and that by void ratio. In the space of degree of saturation and suction, the SWRC at constant void ratio shifts to the direction of higher suctions with decreasing void ratio. However, the relationship between water content and suction is less affected by changes of void ratio. The degree of saturation decreases approximately linearly with increasing void ratio at a constant suction. Moreover, the slope of the line decreases with increasing suction and they show an approximately linear relationship in semi-logarithmical scale. From this linear relationship, the variation of degree of saturation caused by the change in void ratio can be obtained. Correspondingly, SWRC at a constant void ratio can be determined from SWRC at different void ratios.

  6. Continuous quality assessment of atmospheric water vapour measurement techniques: FTIR, Cimel, MFRSR, GPS, and Vaisala RS92

    Directory of Open Access Journals (Sweden)

    M. Schneider

    2010-03-01

    Full Text Available At the Izaña Observatory, water vapour amounts have been measured routinely by different techniques for many years. We intercompare the total precipitable water vapour (PWV amounts measured between 2005 and 2009 by a Fourier Transform Infrared (FTIR spectrometer, a Multifilter Rotating Shadow-band Radiometer (MFRSR, a Cimel sunphotometer, a Global Positioning System (GPS receiver, and daily radiosondes (Vaisala RS92. The long-term characteristics of our study allows a reliable and extensive empirical quality assessment of long-term validity, which is an important prerequisite when applying the data to climate research. We estimate a PWV precision of 1% for the FTIR, about 10% for the MFRSR, Cimel, and GPS (when excluding rather dry conditions, and significantly better than 15% for the RS92 (the detection of different airmasses avoids a better constrained estimation. We show that the MFRSR, Cimel and GPS data quality depends on the atmospheric conditions (humid or dry and that the restriction to clear-sky observations introduces a significant dry bias in the FTIR and Cimel data. In addition, we intercompare the water vapour profiles measured by the FTIR and the Vaisala RS92, which allows the conclusion that both experiments are able to detect lower to upper tropospheric water vapour mixing ratios with a precision of better than 15%.

  7. Effects of water vapour on the structure parameter of the refractive index for near-infrared radiation

    NARCIS (Netherlands)

    Moene, A.F.

    2003-01-01

    The refractive index of air (n) mainly depends on temperature and water vapour content. For near-infrared radiation, temperature is the main determining factor. To determine the structure parameter of temperature (C-T(2)) from the structure parameter of the refractive index (C-n(2)), the influence

  8. The epidermal resistance to diffusion of water vapour : an improved measuring method and field results in Indian corn (Zea mays)

    NARCIS (Netherlands)

    Stigter, C.J.

    1974-01-01

    The resistance of the epidermis of the leaf to diffusion of water vapour can be measured most accurately in the field by closed diffusion porometers. It was possible to overcome the problems related to calibration and to dynamical use of a LiCl humidity sensor in the porometer. The dynamic behaviour

  9. Relative humidity effects on water vapour fluxes measured with closed-path eddy-covariance systems with short sampling lines

    DEFF Research Database (Denmark)

    Fratini, Gerardo; Ibrom, Andreas; Arriga, Nicola

    2012-01-01

    It has been formerly recognised that increasing relative humidity in the sampling line of closed-path eddy-covariance systems leads to increasing attenuation of water vapour turbulent fluctuations, resulting in strong latent heat flux losses. This occurrence has been analyzed for very long (50 m)...

  10. Measurements of mesospheric water vapour, aerosols and temperatures with the Spectral Absorption Line Imager (SALI-AT)

    Science.gov (United States)

    Shepherd, M. G.; Mullins, M.; Brown, S.; Sargoytchev, S. I.

    2001-08-01

    Water vapour concentration is one of the most important, yet one of the least known quantities of the mesosphere. Knowledge of water vapour concentration is the key to understanding many mesospheric processes, including the one that is primary focus of our investigation, mesospheric clouds (MC). The processes of formation and occurrence parameters of MC constitute an interesting problem in their own right, but recently evidence has been provided which suggests that they are a critical indicator of atmospheric change. The aim of the SALI-AT experiment is to make simultaneous (although not strictly collocated) measurements of water vapour, aerosols and temperature in the mesosphere and the mesopause region under twilight condition in the presence of mesospheric clouds. The water vapour will be measured in the regime of solar occultation utilizing a water vapour absorption band at 936 nm wavelength employing the SALI (Spectral Absorption Line Imager) instrument concept. A three-channel zenith photometer, AT-3, with wavelengths of 385 nm, 525 nm, and 1040 nm will measure Mie and Rayleigh scattering giving both mesospheric temperature profiles and the particle size distribution. Both instruments are small, low cost and low mass. It is envisioned that the SALI-AT experiment be flown on a small rocket - the Improved Orion/Hotel payload configuration, from the Andoya Rocket range, Norway. Alternatively the instrument can be flown as a "passenger" on larger rocket carrying other experiments. In either case flight costs are relatively low. Some performance simulations are presented showing that the instrument we have designed will be sufficiently sensitive to measure water vapor in concentrations that are expected at the summer mesopause, about 85 km height.

  11. Experimental Investigation of a Mechanical Vapour Compression Chiller at Elevated Chilled Water Temperatures

    KAUST Repository

    Thu, Kyaw

    2017-05-18

    The performance of a Mechanical Vapour Compression (MVC) chiller is experimentally investigated under operating conditions suitable for sensible cooling. With the emergence of the energy efficient dehumidification systems, it is possible to decouple the latent load from the MVC chillers which can be operated at higher chilled water temperature for handling sensible cooling load. In this article, the performance of the chiller is evaluated at the elevated chilled water outlet temperatures (7 – 17° C) at various coolant temperatures (28 – 32° C) and flow rates (ΔT = 4 and 5° C) for both full- and part-load conditions. Keeping the performance at the AHRI standard as the baseline condition, the efficacy of the chiller in terms of compression ratio, cooling capacity and COP at aforementioned conditions is quantified experimentally. It is observed that for each one-degree Celsius increase in the chilled water temperature, the COP of the chiller improves by about 3.5% whilst the cooling capacity improvement is about 4%. For operation at 17° C chilled water outlet temperature, the improvements in COP and cooling capacity are between 37 – 40% and 40 – 45%, respectively, compared to the performance at the AHRI standards. The performance of the MVC chiller at the abovementioned operation conditions is mapped on the chiller performance characteristic chart.

  12. Water vapour absorption in the clear atmosphere of a Neptune-sized exoplanet.

    Science.gov (United States)

    Fraine, Jonathan; Deming, Drake; Benneke, Bjorn; Knutson, Heather; Jordán, Andrés; Espinoza, Néstor; Madhusudhan, Nikku; Wilkins, Ashlee; Todorov, Kamen

    2014-09-25

    Transmission spectroscopy has so far detected atomic and molecular absorption in Jupiter-sized exoplanets, but intense efforts to measure molecular absorption in the atmospheres of smaller (Neptune-sized) planets during transits have revealed only featureless spectra. From this it was concluded that the majority of small, warm planets evolve to sustain atmospheres with high mean molecular weights (little hydrogen), opaque clouds or scattering hazes, reducing our ability to observe the composition of these atmospheres. Here we report observations of the transmission spectrum of the exoplanet HAT-P-11b (which has a radius about four times that of Earth) from the optical wavelength range to the infrared. We detected water vapour absorption at a wavelength of 1.4 micrometres. The amplitude of the water absorption (approximately 250 parts per million) indicates that the planetary atmosphere is predominantly clear down to an altitude corresponding to about 1 millibar, and sufficiently rich in hydrogen to have a large scale height (over which the atmospheric pressure varies by a factor of e). The spectrum is indicative of a planetary atmosphere in which the abundance of heavy elements is no greater than about 700 times the solar value. This is in good agreement with the core-accretion theory of planet formation, in which a gas giant planet acquires its atmosphere by accreting hydrogen-rich gas directly from the protoplanetary nebula onto a large rocky or icy core.

  13. GNSS-Derived Water Vapour for Riyadh from SOLA IGS Station

    Science.gov (United States)

    Maghrabi, Abdullrahman; Alothman, Abdulaziz; Fernandes, Rui; Aodah, Souad

    2017-04-01

    Water vapor is the most abundant and highly variable component of the important gases in the atmosphere. It influences many physical and thermodynamical processes in the atmosphere and plays an important role in the hydrological cycle and has effects on our climate and weather systems. Water vapour affects the electromagnetic radiation through the atmosphere, which is of significance in fields of astronomy, radar, communications and remote sensing. Precipitable water vapor (PWV) is the amount of water obtained if all the water vapor in the atmosphere were to be compressed to the point at which it condenses into liquid. PWV is difficult to measure adequately due to its variable distribution both spatially and temporally. Most of the current techniques (e.g., radiosondes or satellites) are only available at few locations and not continuously (few observations per day at most). However, in the last decades, GPS observations have been proven to accurately measure the ZTD (Zenith Tropospheric Delay) at high frequencies (normally every 5 minutes) above the station. This quantity can be converted to PWV if temperature and pressure is know at the station location. In early 2004, King Abdulaziz City for Science and Technology (KACST) established a GPS network for geodetic and geophysical applications to contribute to the International GNSS Service IGS. In this study, we will present the first PWV measurements obtained from Global Navigation Satellite System GNSS receiver at the Solar Village (SOLA), 60 km from Riyadh. GNSS observations for the period between 2004-2006 are used to study the daily and seasonal variations of ZTD, and consequently of PWV in SOLA. In addition, we also compare the GNSS-derived PWV with sunphotometer and radiosonde estimates at SOLA in order to evaluate the compatibility of these techniques in a dry climate as the one in Riyadh.

  14. Feasibility of using ammonia-water mixture in high temperature concentrated solar power plants with direct vapour generation

    DEFF Research Database (Denmark)

    Modi, Anish; Knudsen, Thomas; Haglind, Fredrik

    2014-01-01

    is to use direct vapour generation with water/steam as both the heat transfer fluid in the solar receivers and the cycle working fluid. This enables to operate the plant with higher turbine inlet temperatures. Available literature suggests that it is feasible to use ammonia-water mixture at high...... temperatures without corroding the equipment by using suitable additives with the mixture. This paper assesses the thermodynamic feasibility of using ammonia-water mixture in high temperature (450 °C) and high pressure (over 100 bar) concentrated solar power plants with direct vapour generation. The following......Concentrated solar power plants have attracted an increasing interest in the past few years – both with respect to the design of various plant components, and extending the operation hours by employing different types of storage systems. One approach to improve the overall plant performance...

  15. Technical Note: Improved total atmospheric water vapour amount determination from near-infrared filter measurements with sun photometers

    Directory of Open Access Journals (Sweden)

    F. Mavromatakis

    2007-09-01

    Full Text Available In this work we explore the effect of the contribution of the solar spectrum to the recorded signal in wavelengths outside the typical 940-nm filter's bandwidth. We employ gaussian-shaped filters as well as actual filter transmission curves, mainly AERONET data, to study the implications imposed by the non-zero out-of-band contribution to the coefficients used to derive precipitable water from the measured water vapour band transmittance. Published parameterized transmittance functions are applied to the data to determine the filter coefficients. We also introduce an improved, three-parameter, fitting function that can describe the theoretical data accurately, with significantly less residual effects than with the existing functions. The moderate-resolution SMARTS radiative transfer code is used to predict the incident spectrum outside the filter bandpass for different atmospheres, solar geometries and aerosol optical depths. The high-resolution LBLRTM radiative transfer code is used to calculate the water vapour transmittance in the 940-nm band. The absolute level of the out-of-band transmittance has been chosen to range from 10−6 to 10−4, and typical response curves of commercially available silicon photodiodes are included into the calculations.

    It is shown that if the out-of-band transmittance effect is neglected, as is generally the case, then the derived columnar water vapour is mainly underestimated by a few percents. The actual error depends on the specific out-of-band transmittance, optical air mass of observation and water vapour amount. Further investigations will use experimental data from field campaigns to validate these findings.

  16. Water Vapour Propulsion Powered by a High-Power Laser-Diode

    Science.gov (United States)

    Minami, Y.; Uchida, S.

    Most of the laser propulsion schemes now being proposed and developed assume neither power supplies nor on-board laser devices and therefore are bound to remote laser stations like a kite via a laser beam “string”. This is a fatal disadvantage for a space vehicle that flies freely though it is often said that no need of installing an energy source is an advantage of a laser propulsion scheme. The possibility of an independent laser propulsion space vehicle that carries a laser source and a power supply on board is discussed. This is mainly due to the latest development of high power laser diode (LD) technology. Both high specific impulse-low thrust mode and high thrust-low specific impulse mode can be selected by controlling the laser output by using vapour or water as a propellant. This mode change can be performed by switching between a high power continuous wave (cw), LD engine for high thrust with a low specific impulse mode and high power LD pumping Q-switched Nd:YAG laser engine for low thrust with the high specific impulse mode. This paper describes an Orbital Transfer Vehicle equipped with the above-mentioned laser engine system and fuel cell that flies to the Moon from a space platform or space hotel in Earth orbit, with cargo shipment from lunar orbit to the surface of the Moon, including the possibility of a sightseeing trip.

  17. A lidar for water vapour measurements in daytime at Lampedusa, Italy

    Directory of Open Access Journals (Sweden)

    F. Marenco

    2003-06-01

    Full Text Available ENEA is planning to develop a lidar system for measurement of the vertical profi le of water vapour mixing ratio in daytime at a remote site, the Station for Climate Observations located in Lampedusa, Italy. The Raman lidar technique has been retained because of its experimental simplicity with respect to DIAL, and the UV spectral range has been chosen because Raman cross-sections and detector effi ciencies are larger. For a wavelength larger than ~ 300 nm the signal is limited in daytime by sky background, but extinction is acceptable, and the aims of the system can be reached with a strong laser source. The 355 nm wavelength of a frequency-tripled Nd:YAG laser has been retained as this laser source permits to reach a large pulse energy while keeping the system simple to operate. Geometrical form factor calculations need to be performed to evaluate the near-range overlap between the laser beam and the fi eld-of-view of the receiver. Among several options, a dual-receiver system has been retained to account for the several orders of magnitude expected in the backscattered signal intensity: a smaller receiver, with a primary mirror of 200 mm diameter for the 0.2-1 km range, and a larger 500 mm receiver for the 1-3 km range.

  18. Water vapour transport from the tropical Atlantic and summer rainfall in tropical southern Africa

    Energy Technology Data Exchange (ETDEWEB)

    Vigaud, N.; Rouault, M. [University of Cape Town, Oceanography Department, Private Bag 1, Rondebosch (South Africa); Richard, Y.; Fauchereau, N. [UMR 5210 CNRS / Universite de Bourgogne, Centre de Recherches de Climatologie, Dijon (France)

    2007-02-15

    An empirical orthogonal functions analysis of the onshore flow of moisture along the west coast of southern Africa using NCEP-DOE AMIP II Re-analyses suggests two dominant modes of variability that are linked to (a) variations in the circulation linked with the South Atlantic anticyclone (b) the intensity of the flow that penetrates from the tropical Atlantic. The second mode, referred as the Equatorial Westerly mode, contributes the most to moisture input from the Atlantic onto the subcontinent at tropical latitudes. Substantial correlations in austral summer between the Atlantic moisture flux in the tropics and rainfall over the upper lands surrounding the Congo basin suggest the potential role played by this zonal mode of water vapour transport. Composites for austral summer months when this Equatorial Westerly mode had a particularly strong expression, show an enhanced moisture input at tropical latitudes that feeds into the deep convection occurring over the Congo basin. Sustained meridional energy fluxes result in above normal rainfall east and south of the Congo belt. During years of reduced equatorial westerly moisture flux, a deficit of available humidity occurs in the southern tropics. A concomitant eastward shift of deep convection to the southwest Indian ocean and southeastern Africa, leads to below normal rainfall over the uplands surrounding the Congo basin. (orig.)

  19. Effects of SO2 oxidation on ambient aerosol growth in water and ethanol vapours

    Directory of Open Access Journals (Sweden)

    T. Petäjä

    2005-01-01

    Full Text Available Hygroscopicity (i.e. water vapour affinity of atmospheric aerosol particles is one of the key factors in defining their impacts on climate. Condensation of sulphuric acid onto less hygroscopic particles is expected to increase their hygrocopicity and hence their cloud condensation nuclei formation potential. In this study, differences in the hygroscopic and ethanol uptake properties of ultrafine aerosol particles in the Arctic air masses with a different exposure to anthropogenic sulfur pollution were examined. The main discovery was that Aitken mode particles having been exposed to polluted air were more hygroscopic and less soluble to ethanol than after transport in clean air. This aging process was attributed to sulphur dioxide oxidation and subsequent condensation during the transport of these particle to our measurement site. The hygroscopicity of nucleation mode aerosol particles, on the other hand, was approximately the same in all the cases, being indicative of a relatively similar chemical composition despite the differences in air mass transport routes. These particles had also been produced closer to the observation site typically 3–8 h prior to sampling. Apparently, these particles did not have an opportunity to accumulate sulphuric acid on their way to the site, but instead their chemical composition (hygroscopicity and ethanol solubility resembled that of particles produced in the local or semi-regional ambient conditions.

  20. Analysis of global water vapour trends from satellite measurements in the visible spectral range

    Directory of Open Access Journals (Sweden)

    S. Mieruch

    2008-02-01

    Full Text Available Global water vapour total column amounts have been retrieved from spectral data provided by the Global Ozone Monitoring Experiment (GOME flying on ERS-2, which was launched in April 1995, and the SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY onboard ENVISAT launched in March 2002. For this purpose the Air Mass Corrected Differential Optical Absorption Spectroscopy (AMC-DOAS approach has been used. The combination of the data from both instruments provides us with a long-term global data set spanning more than 11 years with the potential of extension up to 2020 by GOME-2 data on MetOp.

    Using linear and non-linear methods from time series analysis and standard statistics the trends of H2O columns and their errors have been calculated. In this study, factors affecting the trend such as the length of the time series, the magnitude of the variability of the noise, and the autocorrelation of the noise are investigated. Special emphasis has been placed on the calculation of the statistical significance of the observed trends, which reveal significant local changes from −5% per year to +5% per year. These significant trends are distributed over the whole globe. Increasing trends have been calculated for Greenland, East Europe, Siberia and Oceania, whereas decreasing trends have been observed for the northwest USA, Central America, Amazonia, Central Africa and the Arabian Peninsular.

  1. Effect of surface albedo, water vapour, and atmospheric aerosols on the cloud-free shortwave radiative budget in the Arctic

    Energy Technology Data Exchange (ETDEWEB)

    Di Biagio, C. [ENEA, Laboratory for Earth Observations and Analyses, Rome (Italy); University of Siena, Department of Earth Science, Siena (Italy); Di Sarra, A. [ENEA, Laboratory for Earth Observations and Analyses, Rome (Italy); Eriksen, P. [Danish Climate Centre, DMI, Danish Meteorological Institute, Copenhagen (Denmark); Ascanius, S.E. [DMI, Danish Meteorological Institute, Qaanaaq (Greenland); Muscari, G. [INGV, Istituto Nazionale di Geofisica e Vulcanologia, Rome (Italy); Holben, B. [NASA Goddard Space Flight Center, Greenbelt, MD (United States)

    2012-08-15

    This study is based on ground-based measurements of downward surface shortwave irradiance (SW), columnar water vapour (wv), and aerosol optical depth ({tau}) obtained at Thule Air Base (Greenland) in 2007-2010, together with MODIS observations of the surface shortwave albedo (A). Radiative transfer model calculations are used in combination with measurements to separate the radiative effect of A ({Delta}SW{sub A}), wv ({Delta}SW{sub wv}), and aerosols ({Delta}SW{sub {tau}}) in modulating SW in cloud-free conditions. The shortwave radiation at the surface is mainly affected by water vapour absorption, which produces a reduction of SW as low as -100 Wm{sup -2} (-18%). The seasonal change of A produces an increase of SW by up to +25 Wm{sup -2} (+4.5%). The annual mean radiative effect is estimated to be -(21-22) Wm{sup -2} for wv, and +(2-3) Wm{sup -2} for A. An increase by +0.065 cm in the annual mean wv, to which corresponds an absolute increase in {Delta}SW{sub wv} by 0.93 Wm{sup -2} (4.3%), has been observed to occur between 2007 and 2010. In the same period, the annual mean A has decreased by -0.027, with a corresponding decrease in {Delta}SW{sub A} by 0.41 Wm{sup -2} (-14.9%). Atmospheric aerosols produce a reduction of SW as low as -32 Wm{sup -2} (-6.7%). The instantaneous aerosol radiative forcing (RF{sub {tau}}) reaches values of -28 Wm{sup -2} and shows a strong dependency on surface albedo. The derived radiative forcing efficiency (FE{sub {tau}}) for solar zenith angles between 55 and 70 is estimated to be (-120.6 {+-} 4.3) for 0.1 < A < 0.2, and (-41.2 {+-} 1.6) Wm{sup -2} for 0.5 < A < 0.6. (orig.)

  2. (Vapour + liquid) equilibrium in (N,N-dimethylacetamide + methanol + water) at the temperature 313.15 K[N,N-Dimethylacetamide; Water; Methanol; Amides; Binary mixtures; Ternary mixtures; (Vapour+liquid) equilibrium; Excess Gibbs free energy; Correlation

    Energy Technology Data Exchange (ETDEWEB)

    Zielkiewicz, Jan. E-mail: jaz@altis.chem.pg.gda.pl

    2003-12-01

    Total vapour pressures, measured at the temperature 313.15 K, are reported for the ternary mixture (N,N-dimethylacetamide + methanol + water), and for binary constituents (N,N-dimethylacetamide + methanol) and (N,N-dimethylacetamide + water). The present results are compared with previously obtained data for binary mixtures (amide + water) and (amide + methanol), where amide=N-methylformamide, N,N-dimethylformamide, N-methyl-acetamide, 2-pyrrolidinone and N-methylpyrrolidinone. Moreover, it was found that excess Gibbs free energy of mixing for binary mixtures varies roughly linearly with the molar volume of amide.

  3. Accuracy assessment of water vapour measurements from in situ and remote sensing techniques during the DEMEVAP 2011 campaign at OHP

    Directory of Open Access Journals (Sweden)

    O. Bock

    2013-10-01

    Full Text Available The Development of Methodologies for Water Vapour Measurement (DEMEVAP project aims at assessing and improving humidity sounding techniques and establishing a reference system based on the combination of Raman lidars, ground-based sensors and GPS. Such a system may be used for climate monitoring, radiosonde bias detection and correction, satellite measurement calibration/validation, and mm-level geodetic positioning with Global Navigation Satellite Systems. A field experiment was conducted in September–October 2011 at Observatoire de Haute-Provence (OHP. Two Raman lidars (IGN mobile lidar and OHP NDACC lidar, a stellar spectrometer (SOPHIE, a differential absorption spectrometer (SAOZ, a sun photometer (AERONET, 5 GPS receivers and 4 types of radiosondes (Vaisala RS92, MODEM M2K2-DC and M10, and Meteolabor Snow White participated in the campaign. A total of 26 balloons with multiple radiosondes were flown during 16 clear nights. This paper presents preliminary findings from the analysis of all these data sets. Several classical Raman lidar calibration methods are evaluated which use either Vaisala RS92 measurements, point capacitive humidity measurements, or GPS integrated water vapour (IWV measurements. A novel method proposed by Bosser et al. (2010 is also tested. It consists in calibrating the lidar measurements during the GPS data processing. The methods achieve a repeatability of 4–5%. Changes in the calibration factor of IGN Raman lidar are evidenced which are attributed to frequent optical re-alignments. When modelling and correcting the changes as a linear function of time, the precision of the calibration factors improves to 2–3%. However, the variations in the calibration factor, and hence the absolute accuracy, between methods and types of reference data remain at the level of 7%. The intercomparison of radiosonde measurements shows good agreement between RS92 and Snow White measurements up to 12 km. An overall dry bias is found

  4. Simulating the global atmospheric response to aircraft water vapour emissions and contrails: a first approach using a GCM

    Directory of Open Access Journals (Sweden)

    M. Ponater

    1996-09-01

    Full Text Available The effect of contrails and aircraft water vapour emissions on global climate is studied by means of a general circulation model (GCM. In a first approach water vapour emissions and mean contrail coverage within the main flight routes are prescribed according to current observations in a simplified manner. A hierarchic experiment strategy with gradual increase of the forcing is applied to identify the resulting climate signals. The water vapour increase to be expected from air traffic is too small to force a detectable radiative or climatic response. The sensitivity of the model climate to the occurrence of contrails appears to be higher. For mid-latitude summer conditions, the high cloud increase experiments show a consistent temperature response pattern. However, its magnitude is statistically significant only for a mean contrail coverage exceeding present-day amounts. Moreover, the magnitude of the contrail climate signal is highly sensitive to the details of the experimental setup due to several non-linearities of the cloud-radiative interaction. Hence, the prescription of contrails in the GCM has to be as careful as possible for an optimal treatment of the problem. Respective recommendations are given.

  5. Simulating the global atmospheric response to aircraft water vapour emissions and contrails: a first approach using a GCM

    Directory of Open Access Journals (Sweden)

    M. Ponater

    Full Text Available The effect of contrails and aircraft water vapour emissions on global climate is studied by means of a general circulation model (GCM. In a first approach water vapour emissions and mean contrail coverage within the main flight routes are prescribed according to current observations in a simplified manner. A hierarchic experiment strategy with gradual increase of the forcing is applied to identify the resulting climate signals. The water vapour increase to be expected from air traffic is too small to force a detectable radiative or climatic response. The sensitivity of the model climate to the occurrence of contrails appears to be higher. For mid-latitude summer conditions, the high cloud increase experiments show a consistent temperature response pattern. However, its magnitude is statistically significant only for a mean contrail coverage exceeding present-day amounts. Moreover, the magnitude of the contrail climate signal is highly sensitive to the details of the experimental setup due to several non-linearities of the cloud-radiative interaction. Hence, the prescription of contrails in the GCM has to be as careful as possible for an optimal treatment of the problem. Respective recommendations are given.

  6. Gravimetric phenotyping of whole plant transpiration responses to atmospheric vapour pressure deficit identifies genotypic variation in water use efficiency.

    Science.gov (United States)

    Ryan, Annette C; Dodd, Ian C; Rothwell, Shane A; Jones, Ros; Tardieu, Francois; Draye, Xavier; Davies, William J

    2016-10-01

    There is increasing interest in rapidly identifying genotypes with improved water use efficiency, exemplified by the development of whole plant phenotyping platforms that automatically measure plant growth and water use. Transpirational responses to atmospheric vapour pressure deficit (VPD) and whole plant water use efficiency (WUE, defined as the accumulation of above ground biomass per unit of water used) were measured in 100 maize (Zea mays L.) genotypes. Using a glasshouse based phenotyping platform with naturally varying VPD (1.5-3.8kPa), a 2-fold variation in WUE was identified in well-watered plants. Regression analysis of transpiration versus VPD under these conditions, and subsequent whole plant gas exchange at imposed VPDs (0.8-3.4kPa) showed identical responses in specific genotypes. Genotype response of transpiration versus VPD fell into two categories: 1) a linear increase in transpiration rate with VPD with low (high WUE) or high (low WUE) transpiration rate at all VPDs, 2) a non-linear response with a pronounced change point at low VPD (high WUE) or high VPD (low WUE). In the latter group, high WUE genotypes required a significantly lower VPD before transpiration was restricted, and had a significantly lower rate of transpiration in response to VPD after this point, when compared to low WUE genotypes. Change point values were significantly positively correlated with stomatal sensitivity to VPD. A change point in stomatal response to VPD may explain why some genotypes show contradictory WUE rankings according to whether they are measured under glasshouse or field conditions. Furthermore, this novel use of a high throughput phenotyping platform successfully reproduced the gas exchange responses of individuals measured in whole plant chambers, accelerating the identification of plants with high WUE. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  7. High-Resolution Vertical Profile Measurements for Carbon Dioxide and Water Vapour Concentrations Within and Above Crop Canopies

    Science.gov (United States)

    Ney, Patrizia; Graf, Alexander

    2017-10-01

    We present a portable elevator-based facility for measuring CO2 , water vapour, temperature and wind-speed profiles between the soil surface and the atmospheric surface layer above crop canopies. The end of a tube connected to a closed-path gas analyzer is continuously moved up and down over the profile range (in our case, approximately 2 m) while concentrations are logged at a frequency of 20 s^{-1} . Using campaign measurements in winter wheat, winter barley and a catch crop mixture (spring 2015 to autumn 2016) during different stages of crop development and different times of the day, we demonstrate a simple approach to correct for time lags, and the resulting profiles of 30-min mean mole fractions of CO2 and H2O over height increments of 0.025 m. The profiles clearly show the effects of soil respiration and photosynthetic carbon assimilation, varying both during the diurnal cycle and during the growing season. Profiles of temperature and wind speed are based on a ventilated finewire thermocouple and a hot-wire anemometer, respectively. Measurements over bare soil and a short plant canopy were analyzed in the framework of Monin-Obukhov similarity theory to check the validity of the measurements and raw-data-processing approach. Derived fluxes of CO2 , latent and sensible heat and momentum show good agreement with eddy-covariance measurements.

  8. Analysis of long time series of GPS precipitable water vapour from IGS reprocessing

    Science.gov (United States)

    Bock, O.; Willis, P.; Bar-Sever, Y.; Wang, J.; Garayt, B.

    2012-12-01

    Humidity is an essential climate variable, which needs to be monitored continuously and accurately. Few observational datasets are available, and most of them suffer from biases, uncertainties and discontinuities (e.g. radiosonde data records or satellite products). To date, precipitable water vapour (PWV) estimates from the International GNSS Service (IGS) network have not been used extensively in the climate monitoring. A reprocessed version of zenith tropospheric delays (ZTDs) has been made available recently for the International GNSS Service (IGS) network. It covers period 1995-2007 and has been updated until 2011 using the same data processing software. This work aims at evaluating the quality of these ZTD solutions and corresponding PWV estimates and assessing their potential for climate monitoring and atmospheric model validation. As a first step, the continuity of IGS reprocessed (repro1) and operational (trop-new) ZTD solution is assessed. Both segments before and after 2007 are compared to a third GPS solution for 160 common stations and to a DORIS solution for more than 50 stations. Both these GPS and DORIS solutions were homogenously reprocessed over the study period. The comparison did not show any significant discontinuity between the two IGS segments. However, the differences are found between the three independent datasets which are explained by the differences in data processing procedures (e.g. antenna models, mapping functions) and techniques (GPS vs. DORIS). But the magnitude of the differences is less than a few millimeters. The reprocessed GPS ZTD estimates were converted into PWV and analysed globally and for different regions. The PWV time series reveal significant variability on inter-annual, seasonal, intra-seasonal and synoptic timescales. The GPS results are overall fairly consistent with ECMWF reanalysis (ERA-Interim). The impact of changes in GPS equipment on PWV trend estimates needs further investigation. Reprocessed GPS PWV

  9. Influence of water vapour on the height distribution of positive ions, effective recombination coefficient and ionisation balance in the quiet lower ionosphere

    Directory of Open Access Journals (Sweden)

    V. Barabash

    2014-03-01

    Full Text Available Mesospheric water vapour concentration effects on the ion composition and electron density in the lower ionosphere under quiet geophysical conditions were examined. Water vapour is an important compound in the mesosphere and the lower thermosphere that affects ion composition due to hydrogen radical production and consequently modifies the electron number density. Recent lower-ionosphere investigations have primarily concentrated on the geomagnetic disturbance periods. Meanwhile, studies on the electron density under quiet conditions are quite rare. The goal of this study is to contribute to a better understanding of the ionospheric parameter responses to water vapour variability in the quiet lower ionosphere. By applying a numerical D region ion chemistry model, we evaluated efficiencies for the channels forming hydrated cluster ions from the NO+ and O2+ primary ions (i.e. NO+.H2O and O2+.H2O, respectively, and the channel forming H+(H2On proton hydrates from water clusters at different altitudes using profiles with low and high water vapour concentrations. Profiles for positive ions, effective recombination coefficients and electrons were modelled for three particular cases using electron density measurements obtained during rocket campaigns. It was found that the water vapour concentration variations in the mesosphere affect the position of both the Cl2+ proton hydrate layer upper border, comprising the NO+(H2On and O2+(H2On hydrated cluster ions, and the Cl1+ hydrate cluster layer lower border, comprising the H+(H2On pure proton hydrates, as well as the numerical cluster densities. The water variations caused large changes in the effective recombination coefficient and electron density between altitudes of 75 and 87 km. However, the effective recombination coefficient, αeff, and electron number density did not respond even to large water vapour concentration variations occurring at other altitudes in the mesosphere. We determined the water

  10. Parametric analysis of a combined dew point evaporative-vapour compression based air conditioning system

    Directory of Open Access Journals (Sweden)

    Shailendra Singh Chauhan

    2016-09-01

    Full Text Available A dew point evaporative-vapour compression based combined air conditioning system for providing good human comfort conditions at a low cost has been proposed in this paper. The proposed system has been parametrically analysed for a wide range of ambient temperatures and specific humidity under some reasonable assumptions. The proposed system has also been compared from the conventional vapour compression air conditioner on the basis of cooling load on the cooling coil working on 100% fresh air assumption. The saving of cooling load on the coil was found to be maximum with a value of 60.93% at 46 °C and 6 g/kg specific humidity, while it was negative for very high humidity of ambient air, which indicates that proposed system is applicable for dry and moderate humid conditions but not for very humid conditions. The system is working well with an average net monthly power saving of 192.31 kW h for hot and dry conditions and 124.38 kW h for hot and moderate humid conditions. Therefore it could be a better alternative for dry and moderate humid climate with a payback period of 7.2 years.

  11. Real-time fluorescence quenching-based detection of nitro-containing explosive vapours: what are the key processes?

    Science.gov (United States)

    Shaw, P E; Burn, P L

    2017-11-15

    The detection of explosives continues to be a pressing global challenge with many potential technologies being pursued by the scientific research community. Luminescence-based detection of explosive vapours with an organic semiconductor has attracted much interest because of its potential for detectors that have high sensitivity, compact form factor, simple operation and low-cost. Despite the abundance of literature on novel sensor materials systems there are relatively few mechanistic studies targeted towards vapour-based sensing. In this Perspective, we will review the progress that has been made in understanding the processes that control the real-time luminescence quenching of thin films by analyte vapours. These are the non-radiative quenching process by which the sensor exciton decays, the analyte-sensor intermolecular binding interaction, and the diffusion process for the analyte vapours in the film. We comment on the contributions of each of these processes towards the sensing response and, in particular, the relative roles of analyte diffusion and exciton diffusion. While the latter has been historically judged to be one of, if not the primary, causes for the high sensitivity of many conjugated polymers to nitrated vapours, recent evidence suggests that long exciton diffusion lengths are unnecessary. The implications of these results on the development of sensor materials for real-time detection are discussed.

  12. Effects of ultraviolet irradiation, pulsed electric field, hot water and ethanol vapours treatment on functional properties of mung bean sprouts.

    Science.gov (United States)

    Goyal, Ankit; Siddiqui, Saleem; Upadhyay, Neelam; Soni, Jyoti

    2014-04-01

    The present investigation was conducted with the objective to study the effects of various treatments and storage conditions on ascorbic acid, total phenols, antioxidant activity and polyphenol oxidase activity of mung bean sprouts. The sprouts subjected to various treatments viz., pulsed electric field (PEF) (10,000 V for 10 s), hot water dip (HWD) (50 °C for 2 min), ethanol vapours (1 h) and UV-Irradiation (10 kJm(-2) in laminar flow chamber for 1 h); and then stored at room (25 ± 1 °C) and low (7 ± 1 °C) temperature conditions. The sprouts were analyzed regularly at 24 h interval till end of shelf life. Different treatments given to sprouts resulted in differential effect on various parameters. The ascorbic acid, total phenols and antioxidant activity were highest in ethanol vapours treated sprouts. There was a general decrease in polyphenol oxidase activity by various treatments. During storage ascorbic acid, total phenols and antioxidant activity of sprouts first increased and then decreased significantly, however, for polyphenol oxidase activity a progressive increase with increase in storage period was observed. The trends were similar at room and low temperature storage conditions. Thus, it can be concluded that the ethanol vapours significantly improved the ascorbic acid content, total phenols and antioxidant activity of mung bean sprouts, both at room as well as low temperature conditions of storage.

  13. SI-traceable and dynamic reference gas mixtures for water vapour at polar and high troposphere atmospheric levels

    Science.gov (United States)

    Guillevic, Myriam; Pascale, Céline; Mutter, Daniel; Wettstein, Sascha; Niederhauser, Bernhard

    2017-04-01

    In the framework of METAS' AtmoChem-ECV project, new facilities are currently being developed to generate reference gas mixtures for water vapour at concentrations measured in the high troposphere and polar regions, in the range 1-20 µmol/mol (ppm). The generation method is dynamic (the mixture is produced continuously over time) and SI-traceable (i.e. the amount of substance fraction in mole per mole is traceable to the definition of SI-units). The generation process is composed of three successive steps. The first step is to purify the matrix gas, nitrogen or synthetic air. Second, this matrix gas is spiked with the pure substance using a permeation technique: a permeation device contains a few grams of pure water in liquid form and loses it linearly over time by permeation through a membrane. In a third step, to reach the desired concentration, the first, high concentration mixture exiting the permeation chamber is then diluted with a chosen flow of matrix gas with one or two subsequent dilution steps. All flows are piloted by mass flow controllers. All parts in contact with the gas mixture are passivated using coated surfaces, to reduce adsorption/desorption processes as much as possible. The mixture can eventually be directly used to calibrate an analyser. The standard mixture produced by METAS' dynamic setup was injected into a chilled mirror from MBW Calibration AG, the designated institute for absolute humidity calibration in Switzerland. The used chilled mirror, model 373LX, is able to measure frost point and sample pressure and therefore calculate the water vapour concentration. This intercomparison of the two systems was performed in the range 4-18 ppm water vapour in synthetic air, at two different pressure levels, 1013.25 hPa and 2000 hPa. We present here METAS' dynamic setup, its uncertainty budget and the first results of the intercomparison with MBW's chilled mirror.

  14. Evaluation of balloon and satellite water vapour measurements in the Southern tropical and subtropical UTLS during the HIBISCUS campaign

    Directory of Open Access Journals (Sweden)

    N. Montoux

    2009-07-01

    Full Text Available Balloon water vapour in situ and remote measurements in the tropical upper troposphere and lower stratosphere (UTLS obtained during the HIBISCUS campaign around 20° S in Brazil in February–March 2004 using a tunable diode laser (μSDLA, a surface acoustic wave (SAW and a Vis-NIR solar occultation spectrometer (SAOZ on a long duration balloon, have been used for evaluating the performances of satellite borne remote water vapour instruments available at the same latitude and measurement period. In the stratosphere, HALOE displays the best precision (2.5%, followed by SAGE II (7%, MIPAS (10%, SAOZ (20–25% and SCIAMACHY (35%, all of which show approximately constant H2O mixing ratios between 20–25 km. Compared to HALOE of ±10% accuracy between 0.1–100 hPa, SAGE II and SAOZ show insignificant biases, MIPAS is wetter by 10% and SCIAMACHY dryer by 20%. The currently available GOMOS profiles of 25% precision show a positive vertical gradient in error for identified reasons. Compared to these, the water vapour of the Reprobus Chemistry Transport Model, forced at pressures higher than 95 hPa by the ECMWF analyses, is dryer by about 1 ppmv (20%.

    In the lower stratosphere between 16–20 km, most notable features are the steep degradation of MIPAS precision below 18 km, and the appearance of biases between instruments far larger than their quoted total uncertainty. HALOE and SAGE II (after spectral adjustment for reducing the bias with HALOE at northern mid-latitudes both show decreases of water vapour with a minimum at the tropopause not seen by other instruments or the model, possibly attributable to an increasing error in the HALOE altitude registration. Between 16–18 km where the water vapour concentration shows little horizontal variability, and where the μSDLA balloon measurements are not perturbed by outgassing, the average mixing ratios reported by the remote sensing instruments are substantially lower than the 4–5

  15. Comparison between Satellite Water Vapour Observations and Atmospheric Models’ Predictions of the Upper Tropospheric Thermal Radiation

    Directory of Open Access Journals (Sweden)

    J. R. Dim

    2011-01-01

    Full Text Available Atmospheric profiles (temperature, pressure, and humidity are commonly used parameters for aerosols and cloud properties retrievals. In preparation of the launch of the Global Change Observation Mission-Climate/Second-Generation GLobal Imager (GCOM-C/SGLI satellite, an evaluation study on the sensitivity of atmospheric models to variations of atmospheric conditions is conducted. In this evaluation, clear sky and above low clouds water vapour radiances of the upper troposphere obtained from satellite observations and those simulated by atmospheric models are compared. The models studied are the Nonhydrostatic ICosahedral Atmospheric Model (NICAM and the National Center for Environmental Protection/Department Of Energy (NCEP/DOE. The satellite observations are from the Terra/Moderate Resolution Imaging Spectroradiometer (Terra/MODIS satellite. The simulations performed are obtained through a forward radiative transfer calculation procedure. The resulting radiances are transformed into the upper tropospheric brightness temperature (UTBT and relative humidity (UTRH. The discrepancies between the simulated data and the observations are analyzed. These analyses show that both the NICAM and the NCEP/DOE simulated UTBT and UTRH have comparable distribution patterns. However the simulations’ differences with the observations are generally lower with the NCEP/DOE than with the NICAM. The NCEP/DOE model outputs very often overestimate the UTBT and therefore present a drier upper troposphere. The impact of the lower troposphere instability (dry convection on the upper tropospheric moisture and the consequences on the models’ results are evaluated through a thunderstorm and moisture predictor (the K-stability index. The results obtained show a positive relation between the instability and the root mean square error (RMSE: observation versus models. The study of the impact of convective clouds shows that the area covered by these clouds increases with the

  16. THE VAPOUR PRESSURES OF AQUEOUS SOLUTIONS WITH SPECIAL REFERENCE TO THE PROBLEM OF THE STATE OF WATER IN BIOLOGICAL FLUIDS

    Science.gov (United States)

    Grollman, Arthur

    1931-01-01

    Data for the depression of vapour pressure are presented for the following aqueous solutions: NaCl (0.03 to 0.1 molar), KCl (0.03 to 0.1 molar), urea (0.05 to 0.5 molar), sucrose (0.05 to 0.10 molar), lactic and succinic acids, creatine, CaCl2 (0.05 molar), and mixtures of these substances with one another and with certain other solutions (gelatin, gum acacia, sea water, LiCl, etc.). The relation of the depression of vapour pressure of a mixed solution to that of solutions of the individual constituents was investigated in order to ascertain to what extent such studies may be used for the determination of the degree of hydration, or of the state of water, in solutions. Organic substances (urea, sucrose, etc.) showed anomalous results which were markedly affected and unpredictable in mixed solutions. They are, therefore, unsuited for the study of water binding. In the case of solutions of inorganic substances—LiCl and CaCl2—the principle of the additive nature of colligative properties is also only approximately true—except perhaps in very dilute solutions. The limitations of the colligative method for determining the degree of hydration have been defined in accord with the above findings. Studies of the vapour pressures of mixtures of gelatin or gum acacia with NaCl or KCl demonstrated that hydration in gelatin is relatively small at pH = 7 and undetectable in gum acacia solutions. The view, therefore, that hydrophilic colloids are strongly hydrated has not been substantiated. The passage from the sol to the gel state also was not accompanied in gelatin or in blood by any appreciable change in the degree of hydration of the hydrophilic colloids present in these substances. PMID:19872614

  17. Line-shape study of water vapour by tunable diode laser spectrometer in the 822 832 nm wavelength region

    Science.gov (United States)

    Ray, A.; Bandyopadhyay, A.; Ray, B.; Biswas, D.; Ghosh, P. N.

    2004-11-01

    A near-infrared tunable diode laser absorption spectrometer is set up to measure the air-induced broadening coefficients and the line-strength parameters of water-vapour overtone transitions within the (2,1,1)←(0,0,0) band in the 822 832 nm wavelength region. A Hitachi HL8311 E double hetero-junction structure diode laser is used as a probe. The diode laser controller is home-built and stable within ±10 μA and ±10 mK, respectively. The laser-head mount has a simple design and provides easy access whenever changing of the laser head is required. The diode laser emission wavelength is thermally tuned between 50 °C and 12 °C. Thermal tuning of the diode laser emission wavelength is used to reveal the mode structure of the diode laser and to probe the overtone-band transitions of water vapour within its operating wavelength range. Current tuning of the diode laser is used at a fixed laser temperature to study the transitions one at a time. A balanced detector is used to improve the S/N ratio of the spectrum. A phase sensitive detection technique is followed to obtain the first-derivative spectra of the overtone transitions. The first-derivative spectra have been recorded at different air pressures inside the sample cell while the water-vapour pressure is kept fixed. The first-derivative spectrum is numerically integrated to obtain the original line shape. The original line shape is fitted with a Voigt profile by using a nonlinear least-squares fit program to extract the air-broadening coefficient and the line-strength parameter. The data obtained in our work is compared with the results of the HITRAN database.

  18. (Vapour + liquid) equilibrium in (N,N-dimethylacetamide + ethanol + water) at the temperature 313.15 K

    Energy Technology Data Exchange (ETDEWEB)

    Zielkiewicz, Jan [Department of Chemistry, Gdansk University of Technology, Narutowicza Str. 11/12, 80-952 Gdansk (Poland)]. E-mail: jaz@altis.chem.pg.gda.pl

    2006-06-15

    Total vapour pressures, measured at the temperature 313.15 K, are reported for the ternary mixture (N,N-dimethylacetamide + ethanol + water), and for binary constituent (N,N-dimethylacetamide + ethanol). The present results are also compared with previously obtained data for (amide + ethanol) binary mixtures, where amide = N-methylformamide, N,N-dimethylformamide, N-methylacetamide, 2-pyrrolidinone, and N-methylpyrrolidinone. We found that excess Gibbs free energy of mixing for binary (amide + ethanol) mixtures varies roughly linearly with the molar volume of amide.

  19. Use of a water-vapour permeable polyurethane film (omiderm) in the non-surgical treatment of aplasia cutis congenita.

    Science.gov (United States)

    Canter, Halil Ibrahim; Vargel, Ibrahim; Nasir, Serdar; Kayikcioglu, Aycan

    2004-01-01

    Aplasia cutis congenita is characterised by congenital absence of all layers of skin, and most commonly affects the scalp. It is often associated with absence of the bone and dura underlining the defective scalp. In this report, we present the result of use of a water-vapour permeable polyurethane film (Omiderm) together with absorbant fine mesh gauze impregnated with 3% bismuth tribromophenate (Xeroform) in the treatment of a cranial defect in a newborn baby of low birth weight, who could not be operated on because of associated medical problems.

  20. In-situ Modelisation of a Greenhouse Climate Including Sensible Heat, Water Vapour and CO2 Balances

    Directory of Open Access Journals (Sweden)

    Bibi-Triki N.

    2013-04-01

    Full Text Available While thermal structures such as greenhouses are complex to model under transient conditions because of coupled heat and mass (H2O and CO2 exchanges between their different parts, systems theory allows a simple analysis of the input/output behaviour of the model. In particular, parameters of the reduced dynamic models can be derived from in-situ measurements on these systems. This paper describes an application of the systems approach to a greenhouse climate model which incorporates CO2 balance, crop transpiration and photosynthesis and the effects of heating, CO2 enrichment, natural ventilation and evaporative cooling. In a first stage, system parameters such as the equivalent thermal mass, the wind dependent coefficient of natural ventilation and the various heat exchange coefficients were identified in situ from sequences of input-output data concerning the heat and water vapour balance, recorded over the crop production period from December to July. Good agreement between measured and computed values of air temperature, air humidity was observed. In a second stage, we have considered simultaneously the sensible heat, water vapour and CO2 exchanges and tested the model against experimental data measured using a commercial greenhouse climate control computer. The identified values of the physical and physiological parameters are close the theoretical values and the accuracy of temperature, humidity and CO2 content is rather good.

  1. Phase correction for ALMA. Investigating water vapour radiometer scaling: The long-baseline science verification data case study

    Science.gov (United States)

    Maud, L. T.; Tilanus, R. P. J.; van Kempen, T. A.; Hogerheijde, M. R.; Schmalzl, M.; Yoon, I.; Contreras, Y.; Toribio, M. C.; Asaki, Y.; Dent, W. R. F.; Fomalont, E.; Matsushita, S.

    2017-09-01

    The Atacama Large millimetre/submillimetre Array (ALMA) makes use of water vapour radiometers (WVR), which monitor the atmospheric water vapour line at 183 GHz along the line of sight above each antenna to correct for phase delays introduced by the wet component of the troposphere. The application of WVR derived phase corrections improve the image quality and facilitate successful observations in weather conditions that were classically marginal or poor. We present work to indicate that a scaling factor applied to the WVR solutions can act to further improve the phase stability and image quality of ALMA data. We find reduced phase noise statistics for 62 out of 75 datasets from the long-baseline science verification campaign after a WVR scaling factor is applied. The improvement of phase noise translates to an expected coherence improvement in 39 datasets. When imaging the bandpass source, we find 33 of the 39 datasets show an improvement in the signal-to-noise ratio (S/N) between a few to 30 percent. There are 23 datasets where the S/N of the science image is improved: 6 by 450 GHz) and long-baseline (>5 km) observations. These inherently have poorer phase stability and are taken in low PWV (python code to allow ALMA users to undertake WVR scaling tests and make improvements to their data.

  2. The δ18O of Atmospheric Water Vapour is Recorded in the Oxygen Isotope Ratios of Leaf water and Organic Molecules at High Relative Humidity

    Science.gov (United States)

    Lehmann, M. M.; Goldsmith, G. R.; Schmid, L.; Siegwolf, R. T.; Gessler, A.; Saurer, M.

    2016-12-01

    The oxygen stable isotope ratios (δ18O) of water and organic molecules in plants hold information about plant physiology, ecohydrology, and environmental conditions. For instance, the δ18O ratio of leaf water reflects both the δ18O ratios of water in the soil and in the atmosphere. This water, which is incorporated into organic molecules at the time of synthesis, thus serves to record the environment in which the plant was growing. However, how δ18O of atmospheric water vapour affects the δ18O ratio of organic molecules remains poorly understood. In order to investigate the effects of fog and rain (e.g. high atmospheric water availability) on δ18O ratios of leaf water and organic molecules, we exposed oak tree saplings (Quercus robur) in wet and dry soil treatments to 18O-depleted water vapour at ca. 90% relative humidity for 5 h. We harvested plant material over 24 h to trace the movement of the isotopic label in water and organics throughout the plant from the leaves to the stem. The atmospheric water vapour caused a strong 18O-depletion in leaf and xylem water, as well as in leaf carbohydrates, with the most negative ratios observed at the end of the fogging. Moreover, the label was clearly observed in twig and stem phloem carbohydrates following a short delay. A detailed compound-specific isotope analysis of the leaf carbohydrates revealed that the label caused an 18O-depletion in fructose, glucose, and sucrose. Quercitol, an oak-specific alditol, did not show 18O-depletion. Clear soil moisture treatment effects were only observed for twig phloem carbohydrates, with a stronger 18O-depletion in wet plants than in dry plants, suggesting retarded leaf-to-phloem sugar export in trees under drought. We demonstrate that labelling with 18O-depleted water is a potential tool to trace the movement and incorporation of oxygen stable isotopes in plants. We clearly show that changes in δ18O of atmospheric water vapour are quickly imprinted on leaf water and

  3. Derivation of canopy resistance for water vapour fluxes over a spruce forest, using a new technique for the viscous sublayer resistance

    DEFF Research Database (Denmark)

    Jensen, N.O.; Hummelshøj, P.

    1995-01-01

    . The trees close their stomata to limit the water loss. This is also shown through a calculation of the canopy resistance to water vapour exchange. During periods around noon and in the afternoon the resistance becomes very high. The calculations are carried out by using a novel theory for the viscous...... sublayer resistance to atmosphere canopy exchange....

  4. Zonal asymmetries in middle atmospheric ozone and water vapour derived from Odin satellite data 2001–2010

    Directory of Open Access Journals (Sweden)

    A. Gabriel

    2011-09-01

    Full Text Available Stationary wave patterns in middle atmospheric ozone (O3 and water vapour (H2O are an important factor in the atmospheric circulation, but there is a strong gap in diagnosing and understanding their configuration and origin. Based on Odin satellite data from 2001 to 2010 we investigate the stationary wave patterns in O3 and H2O as indicated by the seasonal long-term means of the zonally asymmetric components O3* = O3-[O3] and H2O* = H2O-[H2O] ([O3], [H2O]: zonal means. At mid- and polar latitudes we find a pronounced wave one pattern in both constituents. In the Northern Hemisphere, the wave patterns increase during autumn, maintain their strength during winter and decay during spring, with maximum amplitudes of about 10–20 % of the zonal mean values. During winter, the wave one in O3* shows a maximum over the North Pacific/Aleutians and a minimum over the North Atlantic/Northern Europe and a double-peak structure with enhanced amplitude in the lower and in the upper stratosphere. The wave one in H2O* extends from the lower stratosphere to the upper mesosphere with a westward shift in phase with increasing height including a jump in phase at upper stratosphere altitudes. In the Southern Hemisphere, similar wave patterns occur mainly during southern spring. By comparing the observed wave patterns in O3* and H2O* with a linear solution of a steady-state transport equation for a zonally asymmetric tracer component we find that these wave patterns are primarily due to zonally asymmetric transport by geostrophically balanced winds, which are derived from observed temperature profiles. In addition temperature-dependent photochemistry contributes substantially to the spatial structure of the wave pattern in O3* . Further influences, e.g., zonal asymmetries in eddy

  5. Water vapour fluxes trends on different time scales and their relationship with weather and soil drivers: a case study from a dehesa site in South Spain

    Science.gov (United States)

    Polo, María José; Egüen, Marta; Andreu, Ana; Carpintero, Elisabet; Gómez-Giráldez, Pedro; Patrocinio González-Dugo, María

    2017-04-01

    Water vapour fluxes between the soil surface and the atmosphere constitute one of the most important components of the water cycle in the continental areas. Their regime directly affect the availability of water to plants, water storage in surface bodies, air humidity in the boundary layer, snow persistence… among others, and the list of indirectly affected processes comprises a large number of components. Water potential or wetness gradients are some of the main drivers of water vapour fluxes to the atmosphere; soil humidity is usually monitored as key variable in many hydrological and environmental studies, and its estimated series are used to calibrate and validate the modelling of certain hydrological processes. However, such results may differ when water fluxes are used instead of water state variables, such as humidity. This work shows the analysis of high resolution water vapour fluxes series from a dehesa area in South Spain where a complete energy and water fluxes/variables monitoring site has been operating for the last four years. The results include pasture and tree vegetated control points. The daily water budget calculation on both types of sites has been performed from weather and energy fluxes measurements, and soil moisture measurements, and the results have been aggregated on a weekly, monthly and seasonal basis. Comparison between observed trends of soil moisture and calculated trends of water vapour fluxes is included to show the differences arising in terms of the regime of the dominant weather variables in this type of ecosystems. The results identify significant thresholds for each weather variable driver and highlight the importance of the wind regime, which is the somehow forgotten variable in future climate impacts on hydrology. Further work is being carried out to assess water cycle potential trends under future climate conditions and their impacts on the vegetation in dehesa ecosystems.

  6. Improved platelet compatiblity of water vapour glow discharge treated non-woven poly(ethylene terephthalate) leukocyte-reduction filters for different types of platelet concentrates

    NARCIS (Netherlands)

    Kostelijk, E. H.; Klomp, A. J.; Engbers, G. H.; Gouwerok, C. W.; Verhoeven, A. J.; van Aken, W. G.; Feijen, J.; de Korte, D.

    2001-01-01

    Non-woven poly[ethylene terephthalate] (NW-PET) filter fabric, usually used for leucocyte removal of red cells, was modified by water vapour glow discharge (WVGD) treatment to improve platelet compatibility. Modified filter material was evaluated with different kinds of platelet concentrates (PCs).

  7. Improved platelet compatibility of water vapour glow discharge treated non-woven poly(ethylene therephthalate) leukocyte-reduction filters of different types of platelet concentrates

    NARCIS (Netherlands)

    Kostelijk, E.H.; Klomp, A.J.A.; Klomp, A.J.A.; Engbers, G.H.M.; Gouwerok, C.W.N.; van Aken, W.G.; Verhoeven, A.J.; Feijen, Jan; de Korte, D.

    2001-01-01

    Non-woven poly[ethylene terephthalate] (NW-PET) filter fabric, usually used for leucocyte removal of red cells, was modified by water vapour glow discharge (WVGD) treatment to improve platelet compatibility. Modified filter material was evaluated with different kinds of platelet concentrates (PCs).

  8. Properties of alumina films prepared by metal-organic chemical vapour deposition at atmospheric pressure in hte presence of small amounts of water

    NARCIS (Netherlands)

    Haanappel, V.A.C.; Haanappel, V.A.C.; van Corbach, H.D.; Rem, J.B.; Fransen, T.; Gellings, P.J.

    1995-01-01

    Thin alumina films were deposited on stainless steel, type AISI 304. The deposition process was carried out in nitrogen with low partial pressures of water (0–2.6 × 10−2 kPa (0−0.20 mmHg)) by metal-organic chemical vapour deposition (MOCVD) with aluminium-tri-sec-butoxide (ATSB) as the precursor.

  9. Airborne differential absorption lidar for water vapour measurements in the upper troposphere and lower stratosphere in the spectral region around 940 nm

    Energy Technology Data Exchange (ETDEWEB)

    Poberaj, G.

    2000-07-01

    Two all-solid-state laser systems were developed and studied in detail to optimise their performance for an airborne water vapour differential absorption lidar (DIAL). Their special features are high average output powers and excellent spectral properties in the 940-nm spectral region relevant for monitoring very low water vapour contents in the upper troposphere and lower stratosphere. One system is an injection-seeded pulsed Ti:sapphire ring laser with a spectral bandwidth of 105 MHz and an average power of 1.1 W. The other system is an injection-seeded optical parametric oscillator (OPO) in a ring configuration. Using KTP as nonlinear crystal, a signal output with a spectral bandwidth of 140 MHz and an average power of 1.2 W was achieved. Both systems, the Ti:sapphire ring laser and the KTP OPO, possess spectral purity values higher than 99%. The pump source for these systems is a frequency doubled diode-pumped Nd:YAG laser operating at a repetition rate of 100 Hz. The KTP OPO system has been used as a transmitter in a new airborne water vapour DIAL instrument. For the first time, measurements of two-dimensional water vapour distributions with a high vertical (500 m) and horizontal (20 km) resolution across several potential vorticity streamers were performed. Very low water vapour mixing ratios (10-50 ppmv) and strong gradients were observed in the tropopause region. The sensitivity of the DIAL instrument in the centre of a stratospheric intrusion ranges from 3% in the near field to 12% in the far field (4 km). The first comparison experiments with in situ measuring instruments show a good agreement. Considerable differences are found between DIAL measurements and data obtained from the ECMWF operational analyses and a mesoscale numerical model. (orig.)

  10. Si-nanocrystal-based LEDs fabricated by ion implantation and plasma-enhanced chemical vapour deposition

    Science.gov (United States)

    Perálvarez, M.; Barreto, J.; Carreras, Josep; Morales, A.; Navarro-Urrios, D.; Lebour, Y.; Domínguez, C.; Garrido, B.

    2009-10-01

    An in-depth study of the physical and electrical properties of Si-nanocrystal-based MOSLEDs is presented. The active layers were fabricated with different concentrations of Si by both ion implantation and plasma-enhanced chemical vapour deposition. Devices fabricated by ion implantation exhibit a combination of direct current and field-effect luminescence under a bipolar pulsed excitation. The onset of the emission decreases with the Si excess from 6 to 3 V. The direct current emission is attributed to impact ionization and is associated with the reasonably high current levels observed in current-voltage measurements. This behaviour is in good agreement with transmission electron microscopy images that revealed a continuous and uniform Si nanocrystal distribution. The emission power efficiency is relatively low, ~10-3%, and the emission intensity exhibits fast degradation rates, as revealed from accelerated ageing experiments. Devices fabricated by chemical deposition only exhibit field-effect luminescence, whose onset decreases with the Si excess from 20 to 6 V. The absence of the continuous emission is explained by the observation of a 5 nm region free of nanocrystals, which strongly reduces the direct current through the gate. The main benefit of having this nanocrystal-free region is that tunnelling current flow assisted by nanocrystals is blocked by the SiO2 stack so that power consumption is strongly reduced, which in return increases the device power efficiency up to 0.1%. In addition, the accelerated ageing studies reveal a 50% degradation rate reduction as compared to implanted structures.

  11. Si-nanocrystal-based LEDs fabricated by ion implantation and plasma-enhanced chemical vapour deposition

    Energy Technology Data Exchange (ETDEWEB)

    Peralvarez, M; Carreras, Josep; Navarro-Urrios, D; Lebour, Y; Garrido, B [MIND, IN2UB, Department of Electronics, University of Barcelona, C/Marti i Franques 1, PL2, E-08028 Barcelona (Spain); Barreto, J; DomInguez, C [IMB-CNM, CSIC, Bellaterra, E-08193 Barcelona (Spain); Morales, A, E-mail: mperalvarez@el.ub.e [INAOE, Electronics Department, Apartado 51, Puebla 72000 (Mexico)

    2009-10-07

    An in-depth study of the physical and electrical properties of Si-nanocrystal-based MOSLEDs is presented. The active layers were fabricated with different concentrations of Si by both ion implantation and plasma-enhanced chemical vapour deposition. Devices fabricated by ion implantation exhibit a combination of direct current and field-effect luminescence under a bipolar pulsed excitation. The onset of the emission decreases with the Si excess from 6 to 3 V. The direct current emission is attributed to impact ionization and is associated with the reasonably high current levels observed in current-voltage measurements. This behaviour is in good agreement with transmission electron microscopy images that revealed a continuous and uniform Si nanocrystal distribution. The emission power efficiency is relatively low, {approx}10{sup -3}%, and the emission intensity exhibits fast degradation rates, as revealed from accelerated ageing experiments. Devices fabricated by chemical deposition only exhibit field-effect luminescence, whose onset decreases with the Si excess from 20 to 6 V. The absence of the continuous emission is explained by the observation of a 5 nm region free of nanocrystals, which strongly reduces the direct current through the gate. The main benefit of having this nanocrystal-free region is that tunnelling current flow assisted by nanocrystals is blocked by the SiO{sub 2} stack so that power consumption is strongly reduced, which in return increases the device power efficiency up to 0.1%. In addition, the accelerated ageing studies reveal a 50% degradation rate reduction as compared to implanted structures.

  12. Rosetta Alice/VIRTIS observations of the water vapour UV electroglow emissions around comet 67P/Churyumov-Gerasimenko

    Science.gov (United States)

    Chaufray, J.-Y.; Bockelée-Morvan, D.; Bertaux, J.-L.; Erard, S.; Feldman, P. D.; Capaccioni, F.; Schindhelm, E.; Leyrat, C.; Parker, J.; Filacchione, G.; A'Hearn, M. F.; Feaga, L. M.; Noonan, J.; Keeney, B.; Steffl, A. J.; Stern, S. A.; Weaver, H. A.; Broiles, T.; Burch, J.; Clark, G.; Samara, M.

    2017-07-01

    Several UV emission lines of the coma of 67P/Churyumov-Gerasimenko have been observed by Alice/Rosetta before the 67P/CG perihelion. The H and O emissions are mainly produced by impact dissociation of water molecules by suprathermal electrons. In this paper, we explore further the electron dissociative excitation of H2O to produce the UV emissions by using simultaneous observations of water and H Lyman β done by the VIRTIS-H and Alice instruments during four periods of time in 2014 December, 2015 March and 2015 May. We used simple theoretical considerations to link the UV brightness to the water vapour column density. Two cases are studied. In the first case, we assume the suprathermal electron density is decreasing radially as the thermal electron population; in the second case, we assume the suprathermal electron density does not vary radially. The second case seems more consistent with the Rosetta Plasma Consortium Ion and Electron Sensor measurements during 2015 March and May. The efficiency of the electron dissociative excitation of H2O is lower during the three last periods of time studied compared to the first period in 2014 December. The variability of the efficiency of the electron dissociative excitation between the four studied periods is not simply inversely proportional to the square of the comet-Sun distance but is most likely associated with the variability of the suprathermal electron distribution.

  13. CO2 and water vapour exchange in four alpine herbs at two altitudes and under varying light and temperature conditions.

    Science.gov (United States)

    Rawat, A S; Purohit, A N

    1991-06-01

    CO2 and water vapour exchange rates of four alpine herbs namely: Rheum emodi, R. moorcroftianum, Megacarpaea polyandra and Rumex nepalensis were studied under field conditions at 3600 m (natural habitat) and 550 m altitudes. The effect of light and temperature on CO2 and water vapour exchange was studied in the plants grown at lower altitude. In R. moorcroftianum and R. nepalensis, the average photosynthesis rates were found to be about three times higher at 550 m as compared to that under their natural habitat. However, in M. polyandra, the CO2 exchange rates were two times higher at 3600 m than at 550 m but in R. emodi, there were virtually no differences at the two altitudes. These results indicate the variations in the CO2 exchange rates are species specific. The change in growth altitude does not affect this process uniformly.The transpiration rates in R. emodi and M. polyandra were found to be very high at 3600 m compared to 550 m and are attributed to overall higher stomatal conductance in plants of these species, grown at higher altitude. The mid-day closure of stomata and therefore, restriction of transpirational losses of water were observed in all the species at 550 m altitude. In addition to the effect of temperature and relative humidity, the data also indicate some endogenous rhythmic control of stomatal conductance.The temperature optima for photosynthesis was close to 30°C in M. polyandra and around 20°C in the rest of the three species. High temperature and high light intensity, as well as low temperature and high light intensity, adversely affect the net rate of photosynthesis in these species.Both light compensation point and dark respiration rate increased with increasing temperature.The effect of light was more prominent on photosynthesis than the effect of temperature, however, on transpiration the effect of temperature was more prominent than the effect of light intensity.No definite trends were found in stomatal conductance with respect to

  14. Structural and Phase Transformations in Water-Vapour-Plasma-Treated Hydrophilic TiO 2 Films

    National Research Council Canada - National Science Library

    L. Pranevicius; M. Urbonavicius; S. Tuckute; K. Gedvilas; T. Rajackas; L. L. Pranevicius; D. Milcius

    2012-01-01

      We have investigated structural and phase transformations in water-vapor-plasma-treated 200-300 nm thick Ti films, maintained at room temperature, by injecting water vapor into radio frequency (RF...

  15. Simultaneous retrieval of water vapour, temperature and cirrus clouds properties from measurements of far infrared spectral radiance over the Antarctic Plateau

    Science.gov (United States)

    Di Natale, Gianluca; Palchetti, Luca; Bianchini, Giovanni; Del Guasta, Massimo

    2017-03-01

    The possibility separating the contributions of the atmospheric state and ice clouds by using spectral infrared measurements is a fundamental step to quantifying the cloud effect in climate models. A simultaneous retrieval of cloud and atmospheric parameters from infrared wideband spectra will allow the disentanglement of the spectral interference between these variables. In this paper, we describe the development of a code for the simultaneous retrieval of atmospheric state and ice cloud parameters, and its application to the analysis of the spectral measurements acquired by the Radiation Explorer in the Far Infrared - Prototype for Applications and Development (REFIR-PAD) spectroradiometer, which has been in operation at Concordia Station on the Antarctic Plateau since 2012. The code performs the retrieval with a computational time that is comparable with the instrument acquisition time. Water vapour and temperature profiles and the cloud optical and microphysical properties, such as the generalised effective diameter and the ice water path, are retrieved by exploiting the 230-980 cm-1 spectral band. To simulate atmospheric radiative transfer, the Line-By-Line Radiative Transfer Model (LBLRTM) has been integrated with a specifically developed subroutine based on the δ-Eddington two-stream approximation, whereas the single-scattering properties of cirrus clouds have been derived from a database for hexagonal column habits. In order to detect ice clouds, a backscattering and depolarisation lidar, co-located with REFIR-PAD has been used, allowing us to infer the position and the cloud thickness to be used in the retrieval. A climatology of the vertical profiles of water vapour and temperature has been performed by using the daily radiosounding available at the station at 12:00 UTC. The climatology has been used to build an a priori profile correlation to constrain the fitting procedure. An optimal estimation method with the Levenberg-Marquardt approach has been

  16. The Effect of Climate Change on Ozone Depletion through Changes in Stratospheric Water Vapour

    Science.gov (United States)

    Kirk-Davidoff, Daniel B.; Hintsa, Eric J.; Anderson, James G.; Keith, David W.

    1999-01-01

    Several studies have predicted substantial increases in Arctic ozone depletion due to the stratospheric cooling induced by increasing atmospheric CO2 concentrations. But climate change may additionally influence Arctic ozone depletion through changes in the water vapor cycle. Here we investigate this possibility by combining predictions of tropical tropopause temperatures from a general circulation model with results from a one-dimensional radiative convective model, recent progress in understanding the stratospheric water vapor budget, modelling of heterogeneous reaction rates and the results of a general circulation model on the radiative effect of increased water vapor. Whereas most of the stratosphere will cool as greenhouse-gas concentrations increase, the tropical tropopause may become warmer, resulting in an increase of the mean saturation mixing ratio of water vapor and hence an increased transport of water vapor from the troposphere to the stratosphere. Stratospheric water vapor concentration in the polar regions determines both the critical temperature below which heterogeneous reactions on cold aerosols become important (the mechanism driving enhanced ozone depletion) and the temperature of the Arctic vortex itself. Our results indicate that ozone loss in the later winter and spring Arctic vortex depends critically on water vapor variations which are forced by sea surface temperature changes in the tropics. This potentially important effect has not been taken into account in previous scenarios of Arctic ozone loss under climate change conditions.

  17. Structural and Phase Transformations in Water-Vapour-Plasma-Treated Hydrophilic TiO2 Films

    Directory of Open Access Journals (Sweden)

    L. Pranevicius

    2012-01-01

    Full Text Available We have investigated structural and phase transformations in water-vapor-plasma-treated 200–300 nm thick Ti films, maintained at room temperature, by injecting water vapor into radio frequency (RF plasma at different processing powers. Scanning electron microscopy (SEM combined with optical microscopy and surface nanotopography analysis were used to view tracks of adsorbed water layers and to detect bulges or blisters appeared on the surface of treated samples. Rough surfaces with different size of holes (5–20 μm through the entire film thickness have been observed. X-ray diffraction results show that the oxidation rate of Ti film drastically increases in the presence of an adsorbed water on the hydrophilic layer. It is assumed that the defining factor which controls oxidation kinetics is the hydroxyl radicals formation.

  18. Quality assessment of integrated water vapour measurements at the St. Petersburg site, Russia: FTIR vs. MW and GPS techniques

    Science.gov (United States)

    Virolainen, Yana A.; Timofeyev, Yury M.; Kostsov, Vladimir S.; Ionov, Dmitry V.; Kalinnikov, Vladislav V.; Makarova, Maria V.; Poberovsky, Anatoly V.; Zaitsev, Nikita A.; Imhasin, Hamud H.; Polyakov, Alexander V.; Schneider, Matthias; Hase, Frank; Barthlott, Sabine; Blumenstock, Thomas

    2017-11-01

    The cross-comparison of different techniques for atmospheric integrated water vapour (IWV) measurements is the essential part of their quality assessment protocol. We inter-compare the synchronised data sets of IWV values measured by the Bruker 125 HR Fourier-transform infrared spectrometer (FTIR), RPG-HATPRO microwave radiometer (MW), and Novatel ProPak-V3 global navigation satellite system receiver (GPS) at the St. Petersburg site between August 2014 and October 2016. As the result of accurate spatial and temporal matching of different IWV measurements, all three techniques agree well with each other except for small IWV values. We show that GPS and MW data quality depends on the atmospheric conditions; in dry atmosphere (IWV smaller than 6 mm), these techniques are less reliable at the St. Petersburg site than the FTIR method. We evaluate the upper bound of statistical measurement errors for clear-sky conditions as 0.29 ± 0.02 mm (1.6 ± 0.3 %), 0.55 ± 0.02 mm (4.7 ± 0.4 %), and 0.76 ± 0.04 mm (6.3 ± 0.8 %) for FTIR, GPS, and MW methods, respectively. We propose the use of FTIR as a reference method under clear-sky conditions since it is reliable on all scales of IWV variability.

  19. A numerical and experimental analysis of the process of water vapour absorption by a static lithium bromide solution

    Science.gov (United States)

    Goulet, R.; Knikker, R.; Boudard, E.; Stutz, B.; Bonjour, J.

    2014-02-01

    This paper describes a numerical and experimental analysis of the process of water vapour absorption by a static lithium bromide solution. In the experiment, the temperature evolution of the absorbent solution is measured at different heights. The numerical model solves the set of governing equations for the simultaneous heat and mass transfer inside the absorbent by means of the finite-volume method. An iterative method is used to take into account the strong coupling of heat and mass transfer at the interface and variations of thermophysical properties. A moving grid technique is employed to represent the increase of the solution volume. Model results are compared with our measurements and data reported in the literature. The influence of using constant properties is analysed by comparison with the variable properties and experimental results. It is found that this assumption provides acceptable results in the investigated pool absorption cases despite a strong underestimation of the increase of the solution volume in the course of the absorption process.

  20. The first regular measurements of ozone, carbon monoxide and water vapour in the Pacific UTLS by IAGOS

    Directory of Open Access Journals (Sweden)

    Hannah Clark

    2015-08-01

    Full Text Available We present the features seen in the first 2 months (July and August 2012 of data collected over the Pacific by IAGOS (In-service Aircraft for a Global Observing System-equipped aircraft. IAGOS is the continuation and development of the well-known MOZAIC (Measurement of Ozone and Water Vapour on Airbus in-service Aircraft project where scientific instruments were carried on commercially operated A340 aircraft to make measurements of chemical species in the atmosphere. Here, we show data from an aircraft operated by China Airlines on routes from Taipei to Vancouver, which provided the first trans-Pacific measurements by an IAGOS-equipped aircraft. We describe the chemical composition of the extratropical upper troposphere/lower stratosphere (Ex-UTLS across the Pacific basin in the Northern Hemisphere. The observed concentrations of ozone span a range from 18 to 500 ppbv indicating sources in the marine boundary layer and lowermost stratosphere, respectively. Concentrations of carbon monoxide (CO greater than 400 ppbv are observed in the Ex-UTLS suggesting that plumes of pollution have been exported from the continent. These low concentrations of ozone and high concentrations of CO were rarely recorded in 8 yr of MOZAIC observations over the Atlantic.

  1. The Use of Bending Angle Retrieved By GPS Radio Occultation Technique For The Measurement of The Atmospheric Water Vapour Content

    Science.gov (United States)

    Vespe, F.; Benedetto, C.; Pacione, R.

    In the last decade the use of GPS radio occultation technique (GPS RO) has been deeply and widely investigated for retrieving physical and chemical Earth atmospheric parameters. The technique proved to be particularly precise in retrieving temperature profiles with an high vertical resolution (air) in 2 unknown (hydrostatic pressure and temperature). The system cannot be solved for lower troposphere because the water vapour pressu re is not negligible. So we are forced to include some other information such as the humidity computed by the models (ECMWF or NEP) or adding another observable in the system as the zenith troposphere delays estimated by the GPS ground stations. In this work we will investigate the possibility to retrieve humidity using only the bending angles achieved by the GPS RO. In particular, the humidity profiles are extracted differentiating the true bending angle profiles, retrieved by the GPS RO, with the dry ones, obtained by fitting and extrapolating the outer layers bending angles in a dry atmosphere model (exponential or Hopfield). The bending angles will be retrieved by CHAMP and SAC-C GPS RO data. Then the humidity profiles obtained with the proposed technique will be compared and validated with those retrieved with radio-sounding balloons over two sites at different latitudes: Brindisi (Italy) and Singapore (Japan).

  2. The effect of the low-level jet on the poleward water vapour transport in the central region of South America

    Science.gov (United States)

    Berri, Guillermo J.; Inzunza, Juan B.

    The low-level jet (LLJ) in the central region of South America is studied. This LLJ is generated by the daily cycle of convergence and divergence east of the Andes Mountains. We use the 1973-1974 radiosonde and pilot balloon data set from the upper air weather stations, Salta and Resistencia, in northern Argentina to select 10 LLJ cases and another 10 NoLLJ cases (when the LLJ is not present). We use the University of Utah Mesoscale Model to simulate these situations in order to obtain a high-resolution low-level wind field. These model predictions are then used to calculate the meridional water vapour transport across a vertical cross-section, along 26°S in central South America. The results reveal that the LLJs are a very effective mechanism for the poleward water vapour transport.

  3. High sensitivity of a carbon nanowall-based sensor for detection of organic vapours

    Czech Academy of Sciences Publication Activity Database

    Slobodian, P.; Cvelbar, U.; Říha, Pavel; Olejník, R.; Matyáš, J.; Filipič, G.; Watanabe, H.; Tajima, S.; Kondo, H.; Sekine, M.; Hori, M.

    2015-01-01

    Roč. 110, č. 5 (2015), s. 90515-90520 ISSN 2046-2069 Grant - others:Ministerstvo školství, mládeže a tělovýchovy (MŠMT)(CZ) LO1504; Slovenian Research Agency(SI) L2-6769; Slovenian Research Agency(SI) Bi-JAP-2015-2017-3; JSPS Grant-in-Aid for Exploratory Research(JP) 25600123 Institutional research plan: CEZ:AV0Z20600510 Institutional support: RVO:67985874 Keywords : carbon nanowalls * sensing properties * volatile organic vapours Subject RIV: JB - Sensors, Measurment, Regulation Impact factor: 3.289, year: 2015

  4. Positive water vapour feedback in climate models confirmed by satellite data

    Science.gov (United States)

    Rind, D.; Lerner, J.; Chiou, E.-W.; Chu, W.; Larsen, J.; Mccormick, M. P.; Mcmaster, L.

    1991-01-01

    It has recently been suggested that GCMs used to evaluate climate change overestimate the greenhouse effect due to increased concentrations of trace gases in the atmosphere. Here, new satellite-generated water vapor data are used to compare summer and winter moisture values in regions of the middle and upper troposphere that have previously been difficult to observe with confidence. It is found that, as the hemispheres warm, increased convection leads to increased water vapor above 500 mbar in approximate quantitative agreement with results from current climate models. The same conclusion is reached by comparing the tropical western and eastern Pacific regions. Thus, water vapor feedback is not overestimated in models and should amplify the climate response to increased trace-gas concentrations.

  5. Thickness and structure of the water film deposited from vapour on calcite surfaces

    DEFF Research Database (Denmark)

    Bohr, Jakob; Wogelius, Roy A.; Morris, Peter M.

    2010-01-01

    Synchrotron X-ray reflectivity (SXR) was used to measure the thickness of the water film that adsorbs on a {10¯14} cleavage surface of calcite (CaCO3) in a sample chamber where relative humidity could be controlled within the range from......Synchrotron X-ray reflectivity (SXR) was used to measure the thickness of the water film that adsorbs on a {10¯14} cleavage surface of calcite (CaCO3) in a sample chamber where relative humidity could be controlled within the range from...

  6. In situ measurement of CO2 and water vapour isotopic compositions at a forest site using mid-infrared laser absorption spectroscopy.

    Science.gov (United States)

    Wada, Ryuichi; Matsumi, Yutaka; Takanashi, Satoru; Nakai, Yuichiro; Nakayama, Tomoki; Ouchi, Mai; Hiyama, Tetsuya; Fujiyoshi, Yasushi; Nakano, Takashi; Kurita, Naoyuki; Muramoto, Kenichiro; Kodama, Naomi

    2016-12-01

    We conducted continuous, high time-resolution measurements of CO2 and water vapour isotopologues ((16)O(12)C(16)O, (16)O(13)C(16)O and (18)O(12)C(16)O for CO2, and H2(18)O for water vapour) in a red pine forest at the foot of Mt. Fuji for 9 days from the end of July 2010 using in situ absorption laser spectroscopy. The δ(18)O values in water vapour were estimated using the δ(2)H-δ(18)O relationship. At a scale of several days, the temporal variations in δ(18)O-CO2 and δ(18)O-H2O are similar. The orders of the daily Keeling plots are almost identical. A possible reason for the similar behaviour of δ(18)O-CO2 and δ(18)O-H2O is considered to be that the air masses with different water vapour isotopic ratios moved into the forest, and changed the atmosphere of the forest. A significant correlation was observed between δ(18)O-CO2 and δ(13)C-CO2 values at nighttime (r(2)≈0.9) due to mixing between soil (and/or leaf) respiration and tropospheric CO2. The ratios of the discrimination coefficients (Δa/Δ) for oxygen (Δa) and carbon (Δ) isotopes during photosynthesis were estimated in the range of 0.7-1.2 from the daytime correlations between δ(18)O-CO2 and δ(13)C-CO2 values.

  7. Carbon dioxide and water vapour exchange from understory species in boreal forest.

    NARCIS (Netherlands)

    Heijmans, M.M.P.D.; Arp, W.J.; Chapin, F.S.

    2004-01-01

    Although recent eddy covariance measurements in boreal forests provide CO2 and energy exchange data for the whole ecosystem, very little is known about the role of the understory vegetation. We conducted chamber flux measurements in an Alaskan black spruce forest in order to compare CO2 and water

  8. Online analytical investigations on solvent-, temperature- and water vapour-induced phase transformations of citric acid

    Energy Technology Data Exchange (ETDEWEB)

    Helmdach, L.; Ulrich, J. [Martin-Luther-Universitaet Halle-Wittenberg, Zentrum fuer Ingenieurwissenschaft, Verfahrenstechnik/TVT, Halle (Saale) (Germany); Feth, M.P. [Sanofi-Aventis Deutschland GmbH, Chemical and Process Development Frankfurt Chemistry, Frankfurt (Germany)

    2012-09-15

    It was demonstrated exemplarily for the crystallization of citric acid that the usage of an ultrasound device as well as Raman spectroscopy enables the inline measurement and the control of phase transitions. The influence of different solvent compositions (water and ethanol-water) on the crystallization of citric acid was investigated. By increasing the ethanol content the transformation point was shifted towards higher temperatures. In addition, a strong impact on the nucleation point as well as on the crystal habit was detected in ethanol-water mixtures. The results lead to the assumption that a citric acid solvate exists, which is, however, highly unstable upon isolation from mother liquor and converts fast into the known anhydrate or monohydrate forms of citric acid. The presence of such a solvate, however, could not be proven during this study. Furthermore, factors such as temperature and humidity which might influence the phase transition of the solid product were analyzed by Hotstage-Raman Spectroscopy and Water Vapor Sorption Gravimetry-Dispersive Raman Spectroscopy. Both, temperature as well as humidity show a strong influence on the behaviour of CAM. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  9. A water-vapour giga-maser in the active galaxy TXFS2226-184.

    Science.gov (United States)

    Koekemoer, A M; Henkel, C; Greenhill, L J; Dey, A; van Breugel, W; Codella, C; Antonucci, R

    1995-12-14

    Active galactic nuclei are thought to be powered by gas falling into a massive black hole; the different types of active galaxy may arise because we view them through a thick torus of molecular gas at varying angles of inclination. One way to determine whether the black hole is surrounded by a torus, which would obscure the accretion disk around the black hole along certain lines of sight, is to search for water masers, as these exist only in regions with plentiful molecular gas. Since the first detection of an extra-galactic water maser in 1979, they have come to be associated primarily with active galaxies, and have even been used to probe the mass of the central engine. Here we report the detection of a water giga-maser in the radio galaxy TXFS2226-184. The strength of the emission supports a recently proposed theory of maser pumping that allows for even more powerful masers, which might be detectable at cosmological distances. Water masers may accordingly provide a way to determine distances to galaxies outside the usual distance ladder, providing an independent calibration of the Hubble constant.

  10. Experimental study to distinguish the effects of methanol slip and water vapour on a high temperature PEM fuel cell at different operating conditions

    DEFF Research Database (Denmark)

    Thomas, Sobi; Vang, Jakob Rabjerg; Araya, Samuel Simon

    2017-01-01

    The objective of this paper is to separate out the effects of methanol and water vapour on a high temperature polymer electrolyte membrane fuel cell under different temperatures (160°C and 180°C) and current densities (0.2Acm-2, 0.4Acm-2 and 0.6Acm-2). The degradation rates at the different current...... the presence of 5% methanol tends to degrade the cell performance. However, the presence of H2O mitigates some of the adverse effects of methanol. The effect of varying fuel compositions was found to be more prominent at lower current densities. The voltage improves significantly when adding water vapour...... to the anode after pure hydrogen operation at 180°C. A decrease in the total resistance corresponding to the voltage improvement is observed from the impedance spectra. There is minimal variation in performance with the introduction of 3% and 5% methanol along with water vapour in the anode feed at all current...

  11. Study of transport of oxygen and water vapour between cells in valve regulated lead-acid batteries

    Science.gov (United States)

    Culpin, Barry; Peters, Ken

    Valve-regulated lead-acid batteries are maintenance free, safer, office compatible, and have higher volume efficiency than conventional designs. They are universally used in telecommunications and uninterruptible power supply systems. With the electrolyte immobilized in the separator or as a gel, it is feasible for a monobloc battery to have cells that are not fully sealed from one another, that is to have a common gas space, with certain attendant benefits. This study demonstrates that small differences in the saturation level, acid strength or operating temperature of the cells in such designs can initiate a cycle that may subsequently result in failure if the movement of oxygen and water vapour between cells is unrestricted. Cells that are initially out-of-balance will go further out-of-balance at an ever-increasing rate. This situation can also arise in monobloc designs with sealed cells if the intercell seal is inadequate or incomplete. Battery failure is associated with a re-distribution of water between the cells with some drying out and having high impedance. The preferential oxygen absorption in those cells produces heavily sulfated negative plates. Results on batteries tested under a range of overcharge conditions and temperatures are presented to illustrate these effects. The rate at which the cycle occurs depends on the initial relative density of the acid, the temperature or saturation imbalance between the cells, and the size of the interconnecting gas space. Batteries operating under a continuous cycling regime, particularly those with high overcharge currents and voltages that generate large volumes of oxygen, are more prone to this type of failure mode than batteries operating under low overcharge, intermittent cycling, or float conditions.

  12. Effect of water vapour on the molecular structures of supported vanadium oxide catalysts at elevated temperatures

    NARCIS (Netherlands)

    Jehng, Jih-Mirn; Deo, G.; Weckhuysen, B.M.; Wachs, I.E.

    1996-01-01

    The effect of water vapor on the molecular structures of V2O3-supported catalysts (SiO2, Al2o3, TiO2, and CeO2) was investigated by in situ Raman spectroscopy as a function of temperature (from 500°C to 120°C). Under dry conditions only isolated surface VO4 species are present on the dehydrated SiO2

  13. Modelling of the vapour-liquid equilibrium of water and the in situ concentration of H3PO4 in a high temperature proton exchange membrane fuel cell

    Science.gov (United States)

    Kazdal, Timur J.; Lang, Sebastian; Kühl, Frank; Hampe, Manfred J.

    2014-03-01

    The fuel cell technology is a key element for the hydrogen energy economy and therefore crucial for sustainable development. High temperature proton exchange membrane (HT-PEM) fuel cells (FC) can be operated with reformate gas and thus represent an important bridging technology for the energy transition to a renewable energy based system. HT-PEM FCs based on phosphoric acid (PA) are still subject to intense research, investigating the electrolyte behaviour. By enhancing state of the art 2D FEM simulations of FCs with the vapour liquid equilibrium of water-phosphoric acid and evaporation kinetics, a model was created in which the local concentration of PA can be calculated. Knowledge of the concentration field yields the basis for calculating the locally varying ionic conductivity and other physical properties. By describing the volume expansion behaviour of PA it was possible to predict the catalyst particle deactivation due to the swelling of PA. The in situ concentration predicted by the simulation ranges from 96 to 111 wt%. The model was validated using measured data of a single cell design for different temperatures and pressures. By varying the PA content flooding of the simulated fuel cell could be observed and was linked to humidification effects.

  14. Water vapour solubility and conductivity study of the proton conductor BaCe(0.9 − x)ZrxY0.1O(3 − δ)

    DEFF Research Database (Denmark)

    Ricote, Sandrine; Bonanos, Nikolaos; Caboche, G:

    2009-01-01

    in the sample. The direct current conductivity has been measured as a function of oxygen partial pressure, at a water vapour partial pressure of 0.015 atm. The total conductivity has been resolved into a p-type and an ionic component using a fitting procedure appropriate to the assumed defect model....... An estimation of the protonic component was made by assuming a conductivity isotope effect between 1.4 and 1.8. The total conductivity, obtained using impedance spectroscopy has been measured as a function of temperature in the water and heavy water exchanged states. The activation energy has been found to be 0...

  15. High temperature vapour-liquid equilibria of water-polyalcohol mixtures

    OpenAIRE

    Cristino,Ana Filipa Russo de Albuquerque

    2014-01-01

    Tese de doutoramento, Química (Química Tecnológica), Universidade de Lisboa, Faculdade de Ciências, 2014 It is known that the presence of strong hydrogen bonds in the liquid state creates azeotropes, which disappear with the increase of temperature. This behavior suggests that the distillation at high temperatures could provide a good strategy to separate components of binary mixtures such as alcohol-water systems, very relevant in the chemical industry. Biodegradable fuels start to play ...

  16. Improved water vapour spectroscopy in the 4174–4300 cm−1 region and its impact on SCIAMACHY HDO/H2O measurements

    Directory of Open Access Journals (Sweden)

    R. A. Scheepmaker

    2013-04-01

    Full Text Available The relative abundance of the heavy water isotopologue HDO provides a deeper insight into the atmospheric hydrological cycle. The SCanning Imaging Absorption spectroMeter for Atmospheric CartograpHY (SCIAMACHY allows for global retrievals of the ratio HDO/H2O in the 2.3 micron wavelength range. However, the spectroscopy of water lines in this region remains a large source of uncertainty for these retrievals. We therefore evaluate and improve the water spectroscopy in the range 4174–4300 cm−1 and test if this reduces systematic uncertainties in the SCIAMACHY retrievals of HDO/H2O. We use a laboratory spectrum of water vapour to fit line intensity, air broadening and wavelength shift parameters. The improved spectroscopy is tested on a series of ground-based high resolution FTS spectra as well as on SCIAMACHY retrievals of H2O and the ratio HDO/H2O. We find that the improved spectroscopy leads to lower residuals in the FTS spectra compared to HITRAN 2008 and Jenouvrier et al. (2007 spectroscopy, and the retrievals become more robust against changes in the retrieval window. For both the FTS and SCIAMACHY measurements, the retrieved total H2O columns decrease by 2–4% and we find a negative shift of the HDO/H2O ratio, which for SCIAMACHY is partly compensated by changes in the retrieval setup and calibration software. The updated SCIAMACHY HDO/H2O product shows somewhat steeper latitudinal and temporal gradients and a steeper Rayleigh distillation curve, strengthening previous conclusions that current isotope-enabled general circulation models underestimate the variability in the near-surface HDO/H2O ratio.

  17. Correcting atmospheric effects on InSAR with MERIS water vapour data and elevation-dependent interpolation model

    KAUST Repository

    Li, Z. W.

    2012-05-01

    The propagation delay when radar signals travel from the troposphere has been one of the major limitations for the applications of high precision repeat-pass Interferometric Synthetic Aperture Radar (InSAR). In this paper, we first present an elevation-dependent atmospheric correction model for Advanced Synthetic Aperture Radar (ASAR—the instrument aboard the ENVISAT satellite) interferograms with Medium Resolution Imaging Spectrometer (MERIS) integrated water vapour (IWV) data. Then, using four ASAR interferometric pairs over Southern California as examples, we conduct the atmospheric correction experiments with cloud-free MERIS IWV data. The results show that after the correction the rms differences between InSAR and GPS have reduced by 69.6 per cent, 29 per cent, 31.8 per cent and 23.3 per cent, respectively for the four selected interferograms, with an average improvement of 38.4 per cent. Most importantly, after the correction, six distinct deformation areas have been identified, that is, Long Beach–Santa Ana Basin, Pomona–Ontario, San Bernardino and Elsinore basin, with the deformation velocities along the radar line-of-sight (LOS) direction ranging from −20 mm yr−1 to −30 mm yr−1 and on average around −25 mm yr−1, and Santa Fe Springs and Wilmington, with a slightly low deformation rate of about −10 mm yr−1 along LOS. Finally, through the method of stacking, we generate a mean deformation velocity map of Los Angeles over a period of 5 yr. The deformation is quite consistent with the historical deformation of the area. Thus, using the cloud-free MERIS IWV data correcting synchronized ASAR interferograms can significantly reduce the atmospheric effects in the interferograms and further better capture the ground deformation and other geophysical signals.

  18. CM-SAF water vapour and temperature products from ATOVS onboard NOAA and MetOp: 2004-2008, five years of data

    Science.gov (United States)

    Courcoux, N.; Schröder, M.; Steenbergen, T.; Schulz, J.

    2009-04-01

    The major objective of the satellite Application Facility on Climate Monitoring (CM-SAF) is the exploitation of the satellite measurement with state of the art algorithms to derive information about key climate variable of the Earth system. The derived products focus on the atmospheric part of the "Essential Climate Variable" developed within the Global Climate Observing System (GCOS) framework. Furthermore, the CM-SAF products are tailored with respect to the need of the current and potential future users and are developed by applying the GCOS climate monitoring principles as far as possible. Concerning water vapour and temperature, which are essential climate variables, the CM-SAF operationally retrieves water vapour and temperature profiles from ATOVS observations. The ATOVS instruments, namely HIRS, AMSU-A, and AMSU-B are flying onboard the NOAA satellites and now onboard MetOp as well. The CM-SAF ATOVS data have a global coverage with a spatial resolution of 90 km2 and are available as monthly and daily means. The CM-SAF ATOVS retrieved products are vertically integrated water vapour from the surface to 100 hPa, layered vertically integrated water vapour, layered mean temperature and layered mean relative humidity all three on five layers, as well as temperature and water vapour mixing ratio on six pressure levels. A total of 28 CM-SAF ATOVS products is available. The CM-SAF ATOVS data are, for example, valuable products for the evaluation of climate models because of the simultaneous retrieval of temperature and water vapour profiles with global coverage and high quality in the upper troposphere. On the other hand, the CM-SAF ATOVS products are not suitable for monitoring the interannual variability and trends since the bias errors due to orbit shift and decay, and the intersatellite biases are not corrected. The CM-SAF operational processing scheme is using the International ATOVS Processing Package (IAPP) developed by the University of Wisconsin to retrieve

  19. Condensation analysis of water vapour in the presence of inert gas(ses) for the CO2 capture

    OpenAIRE

    Sivalingam, S.;Raindl, M.;Gleis, S.;Spliethoff, H.

    2017-01-01

    The vapour in oxy fuel combustion flue gasses can be condensed using an atmospheric condenser in order to separate and capture the CO2. The conditions of heat transfer are considerably impaired in the presence of non-condensable gasses e.g.CO2, and the over all heat transfer coefficient is drastically reduced when compared to that of the pure vapour. The presented experimental works are conducted to determine the effects of CO2 and N2 as non-condensable gasses in the condensation heat transfe...

  20. Behavioural Change according to the Si/Al Ratio of Successive Na-Mordenites Observed through Their Dielectric Relaxation during Water Vapour Adsorption Process

    Directory of Open Access Journals (Sweden)

    Sekou Diaby

    2016-01-01

    Full Text Available The experimental study of water vapour adsorption phenomenon on a zeolite, by dielectric relaxation measurement, makes it possible to determine the variations in the exchangeable cation hopping activation energy, on the surface of the solid, in relation to the number of adsorbed molecules. The present work shows that it is possible to explain the change observed in the energy, by means of simple assumptions based, on the one hand, on the models used in order to simulate the adsorption process and, on the other hand, on the distribution of the molecules adsorbed near the exchangeable cations. Thus, the phenomenological interpretation suggested here, about the change in the exchangeable cation hopping energy, obtained by dielectric relaxation measurement, makes us with a mind to conceive a simple method for explaining the results leading to new information on the organization of the first adsorbed molecules on the surface of the studied zeolite. Then, it can be verified that these conclusions confirm the assumptions already developed for interpreting the inferences from previous experiments carried out by means of other techniques.

  1. The stable isotopic composition of water vapour above Corsica during the HyMeX SOP1 campaign: insight into vertical mixing processes from lower-tropospheric survey flights

    Science.gov (United States)

    Sodemann, Harald; Aemisegger, Franziska; Pfahl, Stephan; Bitter, Mark; Corsmeier, Ulrich; Feuerle, Thomas; Graf, Pascal; Hankers, Rolf; Hsiao, Gregor; Schulz, Helmut; Wieser, Andreas; Wernli, Heini

    2017-05-01

    Stable isotopes of water vapour are powerful indicators of meteorological processes on a broad range of scales, reflecting evaporation, condensation, and air mass mixing processes. With the recent advent of fast laser-based spectroscopic methods, it has become possible to measure the stable isotopic composition of atmospheric water vapour in situ at a high temporal resolution. Here we present results from such comprehensive airborne spectroscopic isotope measurements in water vapour over the western Mediterranean at a high spatial and temporal resolution. Measurements have been acquired by a customized Picarro L2130-i cavity-ring down spectrometer deployed onboard the Dornier 128 D-IBUF aircraft together with a meteorological flux measurement package during the HyMeX SOP1 (Hydrological cycle in Mediterranean Experiment special observation period 1) field campaign in Corsica, France, during September and October 2012. Taking into account memory effects of the air inlet pipe, the typical time resolution of the measurements was about 15-30 s, resulting in an average horizontal resolution of about 1-2 km. Cross-calibration of the water vapour measurements from all humidity sensors showed good agreement under most flight conditions but the most turbulent ones. In total 21 successful stable isotope flights with 59 flight hours have been performed. Our data provide quasi-climatological autumn average conditions and vertical profiles of the stable isotope parameters δD, δ18O, and d-excess during the study period. A d-excess minimum in the overall average profile is reached in the region of the boundary-layer top, possibly caused by precipitation evaporation. This minimum is bracketed by higher d-excess values near the surface caused by non-equilibrium fractionation, and a maximum above the boundary layer related to the increasing d-excess in very depleted and dry high-altitude air masses. Repeated flights along the same pattern reveal pronounced day-to-day variability

  2. Structural characterisation of silicon-germanium virtual substrate- based heterostructures grown by low pressure chemical vapour deposition

    CERN Document Server

    Mihai-Dilliway, G D

    2002-01-01

    Silicon-germanium heterostructures incorporating compositionally graded virtual substrates are important for the fabrication of a variety of advanced electronic devices. Their successful application depends critically on their surface morphology and defect content. The aim of this research project is to characterise the way in which these structural properties are influenced by the growth parameters used in low pressure chemical vapour deposition (LPCVD) at the Southampton University Microelectronics Centre (SUMC). To this end, a comparative study of the surface quality and the distribution and density of misfit strain relaxation induced defects in SiGe virtual substrate-based heterostructures grown under varying conditions, was carried out. The growth parameters varied have been: growth temperature, initial and final Ge content, Ge concentration gradient, type of Ge grading profile (linear and stepwise) in the virtual substrate, and thickness and presence of a device structure in the capping layer of constan...

  3. Validation of GOME-2/MetOp-A total water vapour column using reference radiosonde data from GRUAN network

    Science.gov (United States)

    Antón, M.; Loyola, D.; Román, R.; Vömel, H.

    2014-09-01

    The main goal of this article is to validate the total water vapour column (TWVC) measured by the Global Ozone Monitoring Experiment-2 (GOME-2) satellite sensor and generated using the GOME Data Processor (GDP) retrieval algorithm developed by the German Aerospace Center (DLR). For this purpose, spatially and temporally collocated TWVC data from highly accurate sounding measurements for the period January 2009-May 2014 at six sites are used. These balloon-borne data are provided by GCOS Reference Upper-Air Network (GRUAN). The correlation between GOME-2 and sounding TWVC data is reasonably good (determination coefficient (R2) of 0.89) when all available radiosondes (1400) are employed in the inter-comparison. When cloud-free cases (544) are selected by means of the satellite cloud fraction (CF), the correlation exhibits a remarkable improvement (R2 ~ 0.95). Nevertheless, analyzing the six datasets together, the relative differences between GOME-2 and GRUAN data shows mean values (in absolute term) of 19% for all-sky conditions and 14% for cloud-free cases, which evidences a notable bias in the satellite TWVC data against the reference balloon-borne measurements. The satellite-sounding TWVC differences show a strong solar zenith angle (SZA) dependence for values above 50° with a stable behaviour for values below this zenith angle. The smallest relative differences found in the inter-comparison (between -5 and +3%) are achieved for those cloud-free cases with SZA below 50°. Furthermore, the detailed analysis of the influence of cloud properties (CF, cloud top albedo (CTA) and cloud top pressure (CTP)) on the satellite-sounding differences reveals, as expected, a large effect of clouds in the GOME-2 TWVC data. For instance, the relative differences exhibit a large negative dependence on CTA, varying from +5 to -20% when CTA rises from 0.3 to 0.9. Finally, the satellite-sounding differences also show a negative dependence on the reference TWVC values, changing from

  4. Validation of GOME-2/MetOp-A total water vapour column using reference radiosonde data from the GRUAN network

    Science.gov (United States)

    Antón, M.; Loyola, D.; Román, R.; Vömel, H.

    2015-03-01

    The main goal of this paper is to validate the total water vapour column (TWVC) measured by the Global Ozone Monitoring Experiment-2 (GOME-2) satellite sensor and generated using the GOME Data Processor (GDP) retrieval algorithm developed by the German Aerospace Centre (DLR). For this purpose, spatially and temporally collocated TWVC data from highly accurate sounding measurements for the period January 2009-May 2014 at six sites are used. These balloon-borne data are provided by the GCOS Reference Upper-Air Network (GRUAN). The correlation between GOME-2 and sounding TWVC data is reasonably good (determination coefficient, R2, of 0.89) when all available radiosondes (1400) are employed in the inter-comparison. When cloud-free cases (544) are selected by means of the satellite cloud fraction (CF < 5%), the correlation exhibits a remarkable improvement (R2 ~ 0.95). Nevertheless, the analysis of the relative differences between GOME-2 and GRUAN data shows a mean absolute bias error (weighted with the combined uncertainty derived from the estimated errors of both data sets) of 15% for all-sky conditions (9% for cloud-free cases). These results evidence a notable bias in the satellite TWVC data against the reference balloon-borne measurements, partially related to the cloudy conditions during the satellite overpass. The detailed analysis of the influence of cloud properties - CF, cloud top albedo (CTA) and cloud top pressure (CTP) - on the satellite-sounding differences reveals, as expected, a large effect of clouds in the GOME-2 TWVC data. For instance, the relative differences exhibit a large negative dependence on CTA, varying from -6 to -23% when CTA rises from 0.3 to 0.8. Furthermore, the satellite-sounding TWVC differences show a strong dependence on the satellite solar zenith angle (SZA) for values above 50°. Hence the smallest relative differences found in this satellite-sounding comparison are achieved for those cloud-free cases with satellite SZA below 50

  5. Vapour pressures, aqueous solubilities, Henry's law constants, partition coefficients between gas/water (Kgw), n-octanol/water (Kow) and gas/n-octanol (Kgo) of 106 polychlorinated diphenyl ethers (PCDE)

    Science.gov (United States)

    Kurz; Ballschmiter

    1999-02-01

    Modelling the environmental fate of persistent organic pollutants like polychlorinated diphenyl ethers (PCDE) requires the knowledge of a number of fundamental physico-chemical properties of these compounds. We report here the physico-chemical properties of 106 PCDEs, which are over 50% of all possible congeners. Vapour pressures P(OL), water solubilities S(H2O), and n-octanol/water partition coefficients K(OW) were determined with chromatographic methods. With these experimental data the Henry's law constants H, gas/water K(GW) and gas/n-octanol K(GO) partition coefficients were calculated. Vapour pressures and water solubilities and n-octanol/water partition coefficients of the PCDEs are close to those of similar groups of organochlorine compounds like polychlorinated biphenyls (PCBs) and dibenzofurans (PCDFs). A similar environmental fate can be predicted and was partially already been observed.

  6. Temperature Humidity Dissimilarity and Heat-to-water-vapour Transport Efficiency Above and Within a Pine Forest Canopy: the Role of the Bowen Ratio

    Science.gov (United States)

    Lamaud, E.; Irvine, M.

    2006-07-01

    Over the past 15 years atmospheric surface-layer experiments over heterogeneous canopies have shown that the vertical transfer of sensible heat and water vapour exhibit a strong dissimilarity. In particular, the sensible-heat-to-water-vapour transport efficiencies generally exceed unity. One of the main consequences is that evaporation (latent heat flux) computed by the flux-variance method is overestimated, as persistently demonstrated by comparisons with evaporation obtained with the eddy-correlation method. Various authors proposed to take into account the temperature humidity dissimilarity to extend the applicability of the flux-variance method in order to compute evaporation from non-uniform surfaces. They attempted to connect the sensible-heat-to-water-vapour transport efficiency (λ) to the correlation coefficient between temperature and humidity turbulent fluctuations ( R Tq ). This approach was found to be successful over ‘wet’ surfaces for which λ can be approximated by R Tq and ‘dry’ surfaces for which λ can be approximated by 1/ R Tq . However, no solution has been proposed until now for intermediate hydrological conditions. We investigated this question using eddy-correlation measurements above and inside a pine forest canopy. For both levels, our data present a strong likeness with previously published results over heterogeneous surfaces. In particular, they confirm that λ is R Tq in wet conditions and 1/ R Tq in dry conditions. Moreover, we defined the range of the Bowen ratio ( Bo) values for which those two approximations are valid (below 0.1 and greater than 1, respectively) and established a relationship between λ, R Tq and Bo for the intermediate range of Bo. We are confident that this new parameterization will enlarge the applicability of the flux-variance method to all kinds of heterogeneous surfaces in various hydrological conditions

  7. The relative importance of water vapour and dust in controlling the variability in radiative heating of the summertime Saharan heat low

    Science.gov (United States)

    Marsham, John H.; Parker, Douglas J.; Todd, Martin C.; Banks, Jamie R.; Brindley, Helen E.; Garcia-Carreras, Luis; Roberts, Alexander J.; Ryder, Claire L.

    2017-04-01

    The summertime Sahara heat low (SHL) is a key component of the West African monsoon (WAM) system but is a key source of uncertainty in global models. There is considerable uncertainty over the relative importance of water vapour and dust concentrations in controlling the radiation budget over the Sahara. This limits our ability to explain the variability and trends in the SHL and WAM systems, and so hampers our ability to reduce model biases. Here we use in situ observations from Fennec supersite-1 in the central Sahara from June 2011 and 2012, as well as satellite retrievals from GERB, to quantify how total column water vapour (TCWV) and dust aerosols control day-to-day variability in the energy balance in observations and ECMWF reanalyses (ERA-I). Results show that the earth-atmosphere system is radiatively heated in June 2011 and 2012. While we are not able to completely disentangle the roles of water vapour, clouds and dust from the observations, the analysis demonstrates that TCWV provides a far stronger control on TOA net radiation, and so the net heating of the earth-atmosphere system, than AOD does. Variations in dust provide a much stronger control on surface heating, but the reduction in surface heating associated with high dust loadings are largely compensated by associated increases in atmospheric heating, and so dust control on net TOA radiation is weak. Dust and TCWV are both important for direct atmospheric heating. ERA-I assimilated radiosondes from the Fennec campaign but uses a monthly dust climatology, and so cannot capture the impact of daily variations in dustiness. Despite this, ERA-I managed to capture the control of TOA net flux by TCWV, with a positive correlation (r = 0.6) between observed and modelled TOA net radiation. Variations in surface net radiation, and so the vertical profile of radiative heating, are not captured in ERA-I, given it does not capture variations in dust. Results show that ventilation of the SHL by cool moist air

  8. Precipitable water vapour content from ESR/SKYNET sun-sky radiometers: validation against GNSS/GPS and AERONET over three different sites in Europe

    Science.gov (United States)

    Campanelli, Monica; Mascitelli, Alessandra; Sanò, Paolo; Diémoz, Henri; Estellés, Victor; Federico, Stefano; Iannarelli, Anna Maria; Fratarcangeli, Francesca; Mazzoni, Augusto; Realini, Eugenio; Crespi, Mattia; Bock, Olivier; Martínez-Lozano, Jose A.; Dietrich, Stefano

    2018-01-01

    The estimation of the precipitable water vapour content (W) with high temporal and spatial resolution is of great interest to both meteorological and climatological studies. Several methodologies based on remote sensing techniques have been recently developed in order to obtain accurate and frequent measurements of this atmospheric parameter. Among them, the relative low cost and easy deployment of sun-sky radiometers, or sun photometers, operating in several international networks, allowed the development of automatic estimations of W from these instruments with high temporal resolution. However, the great problem of this methodology is the estimation of the sun-photometric calibration parameters. The objective of this paper is to validate a new methodology based on the hypothesis that the calibration parameters characterizing the atmospheric transmittance at 940 nm are dependent on vertical profiles of temperature, air pressure and moisture typical of each measurement site. To obtain the calibration parameters some simultaneously seasonal measurements of W, from independent sources, taken over a large range of solar zenith angle and covering a wide range of W, are needed. In this work yearly GNSS/GPS datasets were used for obtaining a table of photometric calibration constants and the methodology was applied and validated in three European ESR-SKYNET network sites, characterized by different atmospheric and climatic conditions: Rome, Valencia and Aosta. Results were validated against the GNSS/GPS and AErosol RObotic NETwork (AERONET) W estimations. In both the validations the agreement was very high, with a percentage RMSD of about 6, 13 and 8 % in the case of GPS intercomparison at Rome, Aosta and Valencia, respectively, and of 8 % in the case of AERONET comparison in Valencia. Analysing the results by W classes, the present methodology was found to clearly improve W estimation at low W content when compared against AERONET in terms of % bias, bringing the

  9. Effects of ultraviolet irradiation, pulsed electric field, hot water dip and ethanol vapours treatment on keeping and sensory quality of mung bean (Vigna radiata L. Wilczek) sprouts.

    Science.gov (United States)

    Goyal, Ankit; Siddiqui, Saleem

    2014-10-01

    The objective of this research work was to evaluate the effects of UV- irradiation, pulsed electric field (PEF), hot water dip (HWD) and ethanol vapours on the quality and storage life of mung bean sprouts (Vigna radiata L. Wilczek). The sprouts were subjected to various treatments viz., UV-Irradiation (10 kJm(-2) in laminar flow chamber for 1 h), PEF (10,000 V for 10s), HWD (50 °C for 2 min) and ethanol vapours (1 h); and then stored in thermocol cups wrapped with perforated cling films at room (25 ± 1 °C) and low (7 ± 1 °C) temperature conditions. The sprouts were analyzed regularly at 24 h interval for sprout length, sprout weight, total soluble solids (TSS), titratable acidity, non-enzymatic browning, total plate count and overall acceptability. Sprout length and weight increased during storage. There was no significant effect of various treatments on sprout length and weight, except in ethanol treatment, where suppression was observed. HWD showed higher TSS and acidity than that of control. The least browning was observed in ethanol treatment. The total plate count was not significantly affected by various treatments. Overall acceptability under various treatments decreased during storage period both at room and low temperature. Hot water and ethanol vapour treated sprouts showed higher acceptability than other treatments. However, the acceptability scores for sprouts remained within the acceptable range (≥6) up to 72 h at room temperature and 120 h at low temperature conditions.

  10. When do Acacia mellifera trees use water? Responses of sap velocity to soil water availability, vapour pressure deficit and global radiation.

    Science.gov (United States)

    de Blécourt, Marleen; Thomsen, Simon; Gröngröft, Alexander; Eschenbach, Annette

    2017-04-01

    Acacia mellifera (multi-stem deciduous tree) is one of the dominant woody species responsible for bush encroachment in southern African savannahs. However, very little is known on water use, transpiration or xylem sap flow of A. mellifera. We analyzed the responses of sap velocity in A. mellifera to soil moisture, vapour pressure deficit and global radiation. This knowledge is necessary to improve hydrological modelling and will as such contribute to our understanding of the impacts of bush encroachment in (semi) arid savannahs on the soil water balance. We monitored sap velocities at two sites that differed in tree density in a semi-arid thornbush savannah in central Namibia (mean annual precipitation = 346 mm). Sap velocities were derived using the Heat Ratio Method. Measurements were done in four periods of 3-4 months between November 2014 and September 2016. The measurement periods covered the transitions between the dry and rainy season and vice versa, and the dry season. In two of these periods we did measurements at all stems of three trees per site (a total of 17-19 stems), while in the other two periods sap velocities were measured on one stem per tree for six to eight trees per site. The study was done in the framework of SASSCAL (Southern African Science Service Centre for Climate Change and Adaptive Land Management) granted by the German Federal Ministry of Education and Research (BMBF). Preliminary results indicate that the day-to-day fluctuations in cumulative daily sap velocity showed a three-phase interaction with soil water tension (minimum soil water tension of four sensors to 1-m depth). Phase I: At soil water tension water tension had little influence on sap velocities, and fluctuations in sapflow seemed to be related to VPD and global radiation. Phase II: At soil water tensions between pF 2.5 and pF 3.2, sap velocities were negatively related to soil water tension. Phase III: At soil water tensions > pF 3.2 no sap flow could be detected.

  11. Simplified heat transfer modeling for Vapour Phase Soldering based on filmwise condensation for different horizontal Printed Circuit Boards

    Science.gov (United States)

    Géczy, Attila; Illés, Balázs; Péter, Zsolt; Illyefalvi-Vitéz, Zsolt

    2015-03-01

    The paper presents a method for investigating heat transfer during a specific reflow soldering method, Vapour Phase Soldering (VPS), where a horizontal Printed Circuit Board (PCB) is heated in vapour medium. The paper presents refined descriptions of filmwise condensation which were investigated and adjusted for the VPS process. The results show a proper and fast approximation of measurements. The dependence of the PCB characteristic length is also investigated.

  12. Vapour pressures, aqueous solubility, Henry's law constants and air/water partition coefficients of 1,8-dichlorooctane and 1,8-dibromooctane.

    Science.gov (United States)

    Sarraute, Sabine; Mokbel, Ilham; Costa Gomes, Margarida F; Majer, Vladimir; Delepine, Hervé; Jose, Jacques

    2006-09-01

    New data on the vapour pressures and aqueous solubility of 1,8-dichlorooctane and 1,8-dibromooctane are reported as a function of temperature between 20 degrees C and 80 degrees C and 1 degrees C and 40 degrees C, respectively. For the vapour pressures, a static method was used during the measurements which have an estimated uncertainty between 3% and 5%. The aqueous solubilities were determined using a dynamic saturation column method and the values are accurate to within +/-10%. 1,8-Dichlorooctane is more volatile than 1,8-dibromooctane in the temperature range covered (p(sat) varies from 3 to 250 Pa and from 0.53 to 62 Pa, respectively) and is also approximately three times more soluble in water (mole fraction solubilities at 25 degrees C of 5.95 x 10(-7) and 1.92 x 10(-7), respectively). A combination of the two sets of data allowed the calculation of the Henry's law constants and the air water partition coefficients. A simple group contribution concept was used to rationalize the data obtained.

  13. Characterization of simultaneous heat and mass transfer phenomena for water vapour condensation on a solid surface in an abiotic environment--application to bioprocesses.

    Science.gov (United States)

    Tiwari, Akhilesh; Kondjoyan, Alain; Fontaine, Jean-Pierre

    2012-07-01

    The phenomenon of heat and mass transfer by condensation of water vapour from humid air involves several key concepts in aerobic bioreactors. The high performance of bioreactors results from optimised interactions between biological processes and multiphase heat and mass transfer. Indeed in various processes such as submerged fermenters and solid-state fermenters, gas/liquid transfer need to be well controlled, as it is involved at the microorganism interface and for the control of the global process. For the theoretical prediction of such phenomena, mathematical models require heat and mass transfer coefficients. To date, very few data have been validated concerning mass transfer coefficients from humid air inflows relevant to those bioprocesses. Our study focussed on the condensation process of water vapour and developed an experimental set-up and protocol to study the velocity profiles and the mass flux on a small size horizontal flat plate in controlled environmental conditions. A closed circuit wind tunnel facility was used to control the temperature, hygrometry and hydrodynamics of the flow. The temperature of the active surface was controlled and kept isothermal below the dew point to induce condensation, by the use of thermoelectricity. The experiments were performed at ambient temperature for a relative humidity between 35-65% and for a velocity of 1.0 ms⁻¹. The obtained data are analysed and compared to available theoretical calculations on condensation mass flux.

  14. The Liquid Vapour Interface

    DEFF Research Database (Denmark)

    Als-Nielsen, Jens Aage

    1985-01-01

    In this short review we are concerned with the density variation across the liquid-vapour interface, i.e. from the bulk density of the liquid to the essentially zero density of the vapour phase. This density variation can in principle be determined from the deviation of the reflectivity from...

  15. A Study of a QCM Sensor Based on TiO2 Nanostructures for the Detection of NO2 and Explosives Vapours in Air

    Directory of Open Access Journals (Sweden)

    Marcin Procek

    2015-04-01

    Full Text Available The paper deals with investigations concerning the construction of sensors based on a quartz crystal microbalance (QCM containing a TiO2 nanostructures sensor layer. A chemical method of synthesizing these nanostructures is presented. The prepared prototype of the QCM sensing system, as well as the results of tests for detecting low NO2 concentrations in an atmosphere of synthetic air have been described. The constructed NO2 sensors operate at room temperature, which is a great advantage, because resistance sensors based on wide gap semiconductors often require much higher operation temperatures, sometimes as high as 500 °C. The sensors constructed by the authors can be used, among other applications, in medical and chemical diagnostics, and also for the purpose of detecting explosive vapours. Reactions of the sensor to nitroglycerine vapours are presented as an example of its application. The influence of humidity on the operation of the sensor was studied.

  16. A Study of a QCM Sensor Based on TiO2 Nanostructures for the Detection of NO2 and Explosives Vapours in Air

    Science.gov (United States)

    Procek, Marcin; Stolarczyk, Agnieszka; Pustelny, Tadeusz; Maciak, Erwin

    2015-01-01

    The paper deals with investigations concerning the construction of sensors based on a quartz crystal microbalance (QCM) containing a TiO2 nanostructures sensor layer. A chemical method of synthesizing these nanostructures is presented. The prepared prototype of the QCM sensing system, as well as the results of tests for detecting low NO2 concentrations in an atmosphere of synthetic air have been described. The constructed NO2 sensors operate at room temperature, which is a great advantage, because resistance sensors based on wide gap semiconductors often require much higher operation temperatures, sometimes as high as 500 °C. The sensors constructed by the authors can be used, among other applications, in medical and chemical diagnostics, and also for the purpose of detecting explosive vapours. Reactions of the sensor to nitroglycerine vapours are presented as an example of its application. The influence of humidity on the operation of the sensor was studied. PMID:25912352

  17. The July 2016 Study of the water VApour in the polar AtmosPhere (SVAAP) campaign at Thule, Greenland: surface radiation budget and role of clouds

    Science.gov (United States)

    Meloni, Daniela; Di Iorio, Tatiana; di Sarra, Alcide; Iaccarino, Antonio; Pace, Giandomenico; Mevi, Gabriele; Muscari, Giovanni; Cacciani, Marco; Gröbner, Julian

    2017-04-01

    The Study of the water VApour in the polar AtmosPhere (SVAAP) project, funded by the Italian Programme for Antarctic Research, is aimed at investigating the surface radiation budget (SRB), the variability of atmospheric water vapour, and the long-term variations in stratospheric composition and structure at Thule, Greenland, in the framework of the international Network for Detection of Atmospheric Composition Change (NDACC). Thule High Arctic Atmospheric Observatory (THAAO, 76.5° N, 68.8° W) is devoted to study climate change and has been operational since 1990, with the contribution of different international institutions: DMI, NCAR, ENEA, INGV, Universities of Roma and Firenze (http://www.thuleatmos-it.it). As part of SVAAP an intensive field campaign was held at Thule from 5 to 28 July 2016. The campaign was also aimed at supporting the installation of VESPA-22, a new microwave radiometer for water vapour profiling in the upper atmosphere and integrated water vapour (IWV), and offered the possibility to study the cloud physical and optical properties and their impact on the SRB. Measurements of downward shortwave (SW) and longwave (LW) irradiance were already available since 2009. Additional observations were added to obtain the SRB and to characterize the atmospheric state: upward SW and LW irradiance, upwelling and downwelling photosynthetically active radiation (PAR), downward irradiance in the 8-14 µm infrared window, temperature and relative humidity tropospheric profiles, IWV, liquid water path (LWP), lidar tropospheric backscattering profiles, sky brightness temperature (BT) in the 9.6-11.5 µm spectral range, visible and infrared sky images, surface meteorological parameters. Moreover, 23 radiosonde were launched during the campaign. Data from the period 14-28 July are presented in this study. The first part of the campaign was characterized by stable cloud-free conditions, while alternation of cloudy and cloud-free sky occurred after 18 July. The

  18. Precipitable water vapour content from ESR/SKYNET sun–sky radiometers: validation against GNSS/GPS and AERONET over three different sites in Europe

    Directory of Open Access Journals (Sweden)

    M. Campanelli

    2018-01-01

    Full Text Available The estimation of the precipitable water vapour content (W with high temporal and spatial resolution is of great interest to both meteorological and climatological studies. Several methodologies based on remote sensing techniques have been recently developed in order to obtain accurate and frequent measurements of this atmospheric parameter. Among them, the relative low cost and easy deployment of sun–sky radiometers, or sun photometers, operating in several international networks, allowed the development of automatic estimations of W from these instruments with high temporal resolution. However, the great problem of this methodology is the estimation of the sun-photometric calibration parameters. The objective of this paper is to validate a new methodology based on the hypothesis that the calibration parameters characterizing the atmospheric transmittance at 940 nm are dependent on vertical profiles of temperature, air pressure and moisture typical of each measurement site. To obtain the calibration parameters some simultaneously seasonal measurements of W, from independent sources, taken over a large range of solar zenith angle and covering a wide range of W, are needed. In this work yearly GNSS/GPS datasets were used for obtaining a table of photometric calibration constants and the methodology was applied and validated in three European ESR-SKYNET network sites, characterized by different atmospheric and climatic conditions: Rome, Valencia and Aosta. Results were validated against the GNSS/GPS and AErosol RObotic NETwork (AERONET W estimations. In both the validations the agreement was very high, with a percentage RMSD of about 6, 13 and 8 % in the case of GPS intercomparison at Rome, Aosta and Valencia, respectively, and of 8 % in the case of AERONET comparison in Valencia. Analysing the results by W classes, the present methodology was found to clearly improve W estimation at low W content when compared against AERONET

  19. The 1997 El Niño impact on clouds, water vapour, aerosols and reactive trace gases in the troposphere, as measured by the Global Ozone Monitoring Experiment

    Directory of Open Access Journals (Sweden)

    D. Loyola

    2006-01-01

    Full Text Available The El Niño event of 1997/1998 caused dry conditions over the Indonesian area that were followed by large scale forest and savannah fires over Kalimantan, Sumatra, Java, and parts of Irian Jaya. Biomass burning was most intense between August and October 1997, and large amounts of ozone precursors, such as nitrogen oxides, carbon monoxide and hydrocarbons were emitted into the atmosphere. In this work, we use satellite measurements from the Global Ozone Monitoring Experiment (GOME sensor to study the teleconnections between the El Niño event of 1997 and the Indonesian fires, clouds, water vapour, aerosols and reactive trace gases (nitrogen dioxide, formaldehyde and ozone in the troposphere.

  20. Experimental evaluation of water vapour cross-sensitivity for accurate eddy covariance measurement of CO2 flux using open-path CO2/H2O gas analysers

    Directory of Open Access Journals (Sweden)

    Fumiyoshi Kondo

    2014-10-01

    Full Text Available Non-dispersive infrared CO2/H2O gas analysers produce erroneous CO2 outputs when CO2 is measured in humid air, unless a correction for water vapour cross-sensitivity is applied. Spectroscopic cross-sensitivities arising from direct absorption interference and from the pressure broadening effect are significant in CO2 flux measurements by the eddy covariance technique using open-path gas analysers over the ocean, as opposed to land-surface measurements, where CO2 fluxes are orders of magnitude larger. In this study, a widely used analyser with manufacturer-determined correction coefficients for both cross-sensitivities was tested by laboratory experiments. Our results showed that the correction coefficient for direct absorption interference was not optimised to calculate CO2 flux accurately, and that the correction coefficient for the pressure broadening caused overestimation of the CO2 mixing ratio flux in the same direction as the water vapour flux. Overestimations of open-path eddy covariance measurements of upward CO2 fluxes in previous ocean observations probably resulted from inaccuracies in both of these correction coefficients. We also found that slight changes in spectroscopic cross-sensitivities due to contamination of the analyser's optical windows by sea salt caused a low bias in CO2 outputs with increasing H2O; however, this contamination effect was not always observed in repeated tests under different contamination conditions. We suggest that previously proposed methods for correcting the effect of optical window contamination is of limited value and that measurement of small CO2 fluxes by the open-path eddy covariance technique over the ocean should be performed after confirming the spectroscopic cross-sensitivity and ensuring that the optical windows are as clean as possible.

  1. Continuous photometric observations at ENEA base in Lampedusa to estimate precipitable water

    Directory of Open Access Journals (Sweden)

    S. Teggi

    2003-06-01

    Full Text Available Water vapour is a variable component of the atmosphere both in space and time. It is one of the most important components because of its effects in many fi elds: Meteorology, Climatology, Remote Sensing, Energy-Budget, Hydrology, etc. This work compares radiometric (sun photometer readings, Global Positioning System (GPS data and a meteorological model forecasted data. The aim is to understand if GPS measurements may help Numerical Weather Prediction (NWP models. It is well known that GPS measurements are affected by the so-called tropospheric delay. Part of it, the so-called wet delay is related mainly to the amount of water vapour along the path of the GPS signal through the troposphere. Precise knowledge of the abundance of water vapour, in space and time, is important for NWP model because water vapour is the predecessor of precipitation. Despite the high variability of water vapour compared to other meteorological fi elds, like pressure and wind, water vapour observations are scarce, so that additional measurements of water vapour are expected to benefi t meteorology. A new sun photometer, which is part of the AERONET (AErosol and RObotic NETwork program, has been installed at the ENEA (Ente per le Nuove tecnologie, l'Energia e l'Ambiente base of Lampedusa Island. The sun photometer is quite close (less then 4 km to an ASI (Agenzia Spaziale Italiana GPS permanent receiver. A long record (summer period of the year 2000 of sun photometric measurements is available for the station at Lampedusa. We found that the GPS and sun photometric data are better correlated (std. dev. about 10 mm for the wet delay than are the GPS measurements with the NWP model predictions. This is an indication that GPS delay data may contain information useful for weather prediction.

  2. Corrigendum to “Relative humidity effects on water vapour fluxes measured with closed-path eddy-covariance systems with short sampling lines” [Agric. Forest Meteorol. 165 (2012) 53–63

    DEFF Research Database (Denmark)

    Fratini, Gerardo; Ibrom, Andreas; Arriga, Nicola

    2012-01-01

    It has been formerly recognised that increasing relative humidity in the sampling line of closed-path eddy-covariance systems leads to increasing attenuation of water vapour turbulent fluctuations, resulting in strong latent heat flux losses. This occurrence has been analyzed for very long (50 m)...

  3. Can painted glass felt or glass fibre cloth be used as vapour barrier?

    DEFF Research Database (Denmark)

    El-Khattam, Amira; Andersen, Mie Them; Hansen, Kurt Kielsgaard

    2014-01-01

    with a ventilated attic where the ceiling may be air tight but has no vapour barrier; post-insulation of the attic may cause the need for a vapour barrier. Placing a vapour barrier above the ceiling can be tiresome and it is difficult to ensure tightness. A simpler way is to paint a vapour barrier directly...... on the ceiling e.g. as an ordinary paint. This paper presents the results of an investigation of the water vapour resistance of surface treatments which are commonly used in-door. The water vapour resistance was measured by the cup method. Aerated concrete was investigated with and without various surface...

  4. Automated dispersive liquid-liquid microextraction coupled to high performance liquid chromatography - cold vapour atomic fluorescence spectroscopy for the determination of mercury species in natural water samples.

    Science.gov (United States)

    Liu, Yao-Min; Zhang, Feng-Ping; Jiao, Bao-Yu; Rao, Jin-Yu; Leng, Geng

    2017-04-14

    An automated, home-constructed, and low cost dispersive liquid-liquid microextraction (DLLME) device that directly coupled to a high performance liquid chromatography (HPLC) - cold vapour atomic fluorescence spectroscopy (CVAFS) system was designed and developed for the determination of trace concentrations of methylmercury (MeHg(+)), ethylmercury (EtHg(+)) and inorganic mercury (Hg(2+)) in natural waters. With a simple, miniaturized and efficient automated DLLME system, nanogram amounts of these mercury species were extracted from natural water samples and injected into a hyphenated HPLC-CVAFS for quantification. The complete analytical procedure, including chelation, extraction, phase separation, collection and injection of the extracts, as well as HPLC-CVAFS quantification, was automated. Key parameters, such as the type and volume of the chelation, extraction and dispersive solvent, aspiration speed, sample pH, salt effect and matrix effect, were thoroughly investigated. Under the optimum conditions, linear range was 10-1200ngL(-1) for EtHg(+) and 5-450ngL(-1) for MeHg(+) and Hg(2+). Limits of detection were 3.0ngL(-1) for EtHg(+) and 1.5ngL(-1) for MeHg(+) and Hg(2+). Reproducibility and recoveries were assessed by spiking three natural water samples with different Hg concentrations, giving recoveries from 88.4-96.1%, and relative standard deviations <5.1%. Copyright © 2017 Elsevier B.V. All rights reserved.

  5. A review of exposure conditions and possible health effects associated with aerosol and vapour from low-aromatic oil-based drilling fluids.

    Science.gov (United States)

    Eide, I

    1990-04-01

    This paper reviews investigations on possible health effects after inhalation of aerosol and vapour from the low-aromatic oil-based drilling fluids which have replaced the diesel-based fluids. The main advantage of the low-aromatic base oils with respect to health hazard is their lower volatility. However, some aliphatic and naphthenic hydrocarbons are distributed more efficiently to the brain than are the corresponding aromatic ones. Reducing the content of aromatic hydrocarbons becomes particularly important when the upper end of the boiling point range is sufficiently high for the base oil to contain carcinogenic polycyclic aromatic hydrocarbons (PAH). As a result of enclosure and local extract ventilation it has been possible to reduce time-weighted average concentrations of aerosol and vapour to below 100 mg m-3. Effects on the central nervous system have only been observed at higher concentrations of the actual hydrocarbons, and male rat hydrocarbon nephropathy is not considered predictive of a normal human response. Insufficient information is available on possible long-term effects of exposure to the low-aromatic oil-based drilling fluids, especially regarding carcinogenicity and changes in the lungs.

  6. Effects of drought and changes in vapour pressure deficit on water relations of Populusdeltoides growing in ambient and elevated CO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Bobich, E.G.; Barron-Gafford, G.A.; Rascher, K.G. [Columbia Univ., Oracle, AZ (United States). Biosphere 2 Center; Murthy, R. [Columbia Univ., Oracle, AZ (United States). Biosphere 2 Center, Earth and Environmental Sciences, Lamont-Doherty Earth Observatory

    2010-07-15

    According to the Intergovernmental Panel on Climate Change (IPCC), changes in the earth's climate are expected to become more extreme as carbon dioxide (CO{sub 2}) concentrations increase over the next century. This study examined the means by which growth CO{sub 2} concentration affects anatomy and water relation responses to drought and vapour pressure deficit (VPD). Yearly coppiced, 4-year-old Populus deltoides clones grown in either ambient or elevated CO{sub 2} for 3 years were examined to determine if trees growing in elevated CO{sub 2} during drought would have a lower volume flux density of water (JV), stomatal conductance (gs) and transpiration per leaf area (E), as well as a lower stomatal density and a greater stomatal response to drought and changes in VPD than would trees in ambient CO{sub 2}. The study showed that trees in elevated CO{sub 2} actually had higher JV values, but did not differ from trees in ambient CO{sub 2} in terms of gs or E under saturating light or E scaled from JV. The higher JV in elevated CO{sub 2} was attributed to the greater leaf area in the trees and not from differences in gs. Plants in elevated CO{sub 2} had greater absolute leaf loss during the drought, but the percentage of leaf area lost was similar to that of trees in ambient CO{sub 2}. Under saturating light, gs and E were influenced by changes in VPD after the first 9 days of the experiment, which coincided with a large decrease in water potential. It was concluded that longer-term growth of P. deltoides clone under elevated CO{sub 2} did not improve the effects of drought and high VPD on plant and water relations. 56 refs., 3 tabs., 4 figs.

  7. An Analysis on the Moisture and Thermal Protective Performance of Firefighter Clothing Based on Different Layer Combinations and Effect of Washing on Heat Protection and Vapour Transfer Performance

    Directory of Open Access Journals (Sweden)

    Ozgur Atalay

    2015-01-01

    Full Text Available Fabric assemblies for firefighting clothing have been tested for heat protection and comfort. The constituent materials and fabric structures have been specifically selected and tailored for firefighters’ clothing. In order to do this, four types of outer shell fabrics, four types of moisture barrier fabrics, and four types of heat barriers with different weights and material compositions were used to make a multilayered fabric assembly. Heat transfer (flame, heat transfer (radiant, and water vapour resistance tests were conducted according to the latest EN469 test standard which also recommends washing tests. These tests reveal that material content and material brand have considerable effect on the required performance levels of heat protection. In addition, while washing tests have improved water vapor transfer properties, they have a deteriorating effect on heat protection performance. Considering heat protection and moisture comfort properties, the optimal assemblies are thereby identified.

  8. An atlas of mean distribution of precipitable water vapour over the tropical Indian Ocean for the year 1979

    Digital Repository Service at National Institute of Oceanography (India)

    RameshKumar, M.R.; Sathe, P.V.; Muraleedharan, P.M.; Rao, L.V.G.

    The monthly mean maps of the precipitable water (PW) over the tropical Indian Ocean are prepared using the data derived from the Nimbus 7 Scanning Multichannel Microwave Radiometer (SMMR) sensor for the period January to December, 1979. The PW...

  9. Effect of water vapour condensation on the radon content in subsurface air in a hypogeal inactive-volcanic environment in Galdar cave, Spain

    Science.gov (United States)

    Fernandez-Cortes, A.; Benavente, D.; Cuezva, S.; Cañaveras, J. C.; Alvarez-Gallego, M.; Garcia-Anton, E.; Soler, V.; Sanchez-Moral, S.

    2013-08-01

    Fluctuations of trace gas activity as a response to variations in weather and microclimate conditions were monitored over a year in a shallow volcanic cave (Painted Cave, Galdar, Canary Islands, Spain). 222Rn concentration was used due to its greater sensitivity to hygrothermal variations than CO2 concentration. Radon concentration in the cave increases as effective vapour condensation within the porous system of the rock surfaces inside the cave increases due to humidity levels of more than 70%. Condensed water content in pores was assessed and linked to a reduction in the direct passage of trace gases. Fluctuations in radon activity as a response to variations in weather and microclimate conditions were statistically identified by clustering entropy changes on the radon signal and parameterised to predict radon concentration anomalies. This raises important implications for other research fields, including the surveillance of shallow volcanic and seismic activity, preventive conservation of cultural heritage in indoor spaces, indoor air quality control and studies to improve understanding of the role of subterranean terrestrial ecosystems as reservoirs and/or temporary sources of trace gases.

  10. Mean ozone and water vapour height profiles for Southern hemisphere region using radiosonde or ozonesonde and haloe satelite data

    CSIR Research Space (South Africa)

    Sivakumar, V

    2009-01-01

    Full Text Available The aim of this work is to construct a model (mean) profile for ozone and water vapor in Southern hemisphere latitude using 14 years (1993-2006) of Halogen Occultation Experiment (HALOE) satellite data and about 10 years (1998-2007) of the Southern...

  11. Mass-independent fractionation of oxygen isotopes during H2O2 formation by gas-phase discharge from water vapour

    Science.gov (United States)

    Velivetskaya, Tatiana A.; Ignatiev, Alexander V.; Budnitskiy, Sergey Y.; Yakovenko, Victoria V.; Vysotskiy, Sergey V.

    2016-11-01

    Hydrogen peroxide is an important atmospheric component involved in various gas-phase and aqueous-phase transformation processes in the Earth's atmosphere. A study of mass-independent 17O anomalies in H2O2 can provide additional insights into the chemistry of the modern atmosphere and, possibly, of the ancient atmosphere. Here, we report the results of laboratory experiments to study the fractionation of three oxygen isotopes (16O, 17O, and 18O) during H2O2 formation from products of water vapour dissociation. The experiments were carried out by passing an electrical discharge through a gaseous mixture of helium and water at atmospheric pressure. The effect of the presence of O2 in the gas mixture on the isotopic composition of H2O2 was also investigated. All of the experiments showed that H2O2 produced under two different conditions (with or without O2 added in the gas mixtures) was mass-independently fractionated (MIF). We found a positive MIF signal (∼1.4‰) in the no-O2 added experiments, and this signal increased to ∼2.5‰ once O2 was added (1.6% mixing ratio). We suggest that if O2 concentrations are very low, the hydroxyl radical recombination reaction is the dominant pathway for H2O2 formation and is the source of MIF in H2O2. Although H2O2 formation via a hydroxyl radical recombination process is limited in the modern atmosphere, it would be possible in the Archean atmosphere when O2 was a trace constituent, and H2O2 would be mass-independently fractionated. The anomalous 17O excess, which was observed in H2O2 produced by spark discharge experiments, may provide useful information about the radical chemistry of the ancient atmosphere and the role of H2O2 in maintaining and controlling the atmospheric composition.

  12. On the relation of 6.7-micron water vapour features to isentropic distributions of potential vorticity

    Science.gov (United States)

    Manney, Gloria L.; Stanford, John L.

    1987-01-01

    Currently available isentropic maps of potential vorticity (IPV maps) are of low resolution. In this note, the possibility of using 6.7-micron satellite-derived water vapor measurements to obtain higher resolution information about IPV distributions is examined. While attempts to related the two data sets analytically have so far proved unsuccessful, a qualitative comparison shows very similar features in both. The results obtained here suggest that, over limited areas, it may be possible to use 6.7-micron brightness temperatures to obtain approximate contours for water vapor mixing ratio on a particular isentropic surface in the upper troposphere. For areas free of high clouds, these contours are expected to parallel the IPV contours on this surface. In a case study, the resulting map exhibits dramatically increased horizontal resolution compared with present IPV maps, detailing an intriguing upper-tropospheric feature at subsynoptic scales.

  13. A ``nano-windmill'' driven by a flux of water vapour: a comparison to the rotating ATPase

    Science.gov (United States)

    Nitoń, Patrycja; Żywociński, Andrzej; Fiałkowski, Marcin; Hołyst, Robert

    2013-09-01

    We measure the frequency of collective molecular precession as a function of temperature in the ferroelectric liquid crystalline monolayer at the water-air interface. This movement is driven by the unidirectional flux of evaporating water molecules. The collective rotation in the monolayer with angular velocities ω ~ 1 s-1 (at T = 312 K) to 10-2 s-1 (at T = 285.8 K) is 9 to 14 orders of magnitude slower than rotation of a single molecule (typically ω ~ 109 to 1012 s-1). The angular velocity reaches 0 upon approach to the two dimensional liquid-to-solid transition in the monolayer at T = 285.8 K. We estimate the rotational viscosity, γ1, in the monolayer and the torque, Γ, driving this rotation. The torque per molecule equals Γ = 5.7 × 10-8 pN nm at 310 K (γ1 = 0.081 Pa s, ω = 0.87 s-1). The energy generated during one turn of the molecule at the same temperature is W = 3.5 × 10-28 J. Surprisingly, although this energy is 7 orders of magnitude smaller than the thermal energy, kBT (310 K) = 4.3 × 10-21 J, the rotation is very stable. The potential of the studied effect lies in the collective motion of many (>1012) ``nano-windmills'' acting ``in concerto'' at the scale of millimetres. Therefore, such systems are candidates for construction of artificial molecular engines, despite the small energy density per molecular volume (5 orders of magnitude smaller than for a single ATPase).We measure the frequency of collective molecular precession as a function of temperature in the ferroelectric liquid crystalline monolayer at the water-air interface. This movement is driven by the unidirectional flux of evaporating water molecules. The collective rotation in the monolayer with angular velocities ω ~ 1 s-1 (at T = 312 K) to 10-2 s-1 (at T = 285.8 K) is 9 to 14 orders of magnitude slower than rotation of a single molecule (typically ω ~ 109 to 1012 s-1). The angular velocity reaches 0 upon approach to the two dimensional liquid-to-solid transition in the monolayer

  14. A "nano-windmill" driven by a flux of water vapour: a comparison to the rotating ATPase.

    Science.gov (United States)

    Nitoń, Patrycja; Żywociński, Andrzej; Fiałkowski, Marcin; Hołyst, Robert

    2013-10-21

    We measure the frequency of collective molecular precession as a function of temperature in the ferroelectric liquid crystalline monolayer at the water-air interface. This movement is driven by the unidirectional flux of evaporating water molecules. The collective rotation in the monolayer with angular velocities ω ~ 1 s(-1) (at T = 312 K) to 10(-2) s(-1) (at T = 285.8 K) is 9 to 14 orders of magnitude slower than rotation of a single molecule (typically ω ~ 10(9) to 10(12) s(-1)). The angular velocity reaches 0 upon approach to the two dimensional liquid-to-solid transition in the monolayer at T = 285.8 K. We estimate the rotational viscosity, γ1, in the monolayer and the torque, Γ, driving this rotation. The torque per molecule equals Γ = 5.7 × 10(-8) pN nm at 310 K (γ1 = 0.081 Pa s, ω = 0.87 s(-1)). The energy generated during one turn of the molecule at the same temperature is W = 3.5 × 10(-28) J. Surprisingly, although this energy is 7 orders of magnitude smaller than the thermal energy, kBT (310 K) = 4.3 × 10(-21) J, the rotation is very stable. The potential of the studied effect lies in the collective motion of many (>10(12)) "nano-windmills" acting "in concerto" at the scale of millimetres. Therefore, such systems are candidates for construction of artificial molecular engines, despite the small energy density per molecular volume (5 orders of magnitude smaller than for a single ATPase).

  15. Vapour pressures, aqueous solubilities, Henry's Law constants, and octanol/water partition coefficients of a series of mixed halogenated dimethyl bipyrroles.

    Science.gov (United States)

    Tittlemier, Sheryl A; Braekevelt, Eric; Halldorson, Thor; Reddy, Christopher M; Norstrom, Ross J

    2004-12-01

    Basic physical-chemical properties of five bromine and chlorine containing mixed halogenated dimethyl bipyrroles (HDBPs) were determined using established methods. Subcooled liquid vapour pressures (P(o)(L,25)), aqueous solubilities (S(w,25)), and octanol/water partition coefficients (K(ow)) were determined using the gas chromatography-retention time, generator column, and slow-stirring methods, respectively. Henry's Law constants (H25) were estimated using experimentally-derived P(o)(L) and S(w,25) data. Values of all four properties were generally similar to those reported for other polyhalogenated aromatic compounds [P(o)(L,25) = (7.55-191) x 10(-6) Pa; S(w,25) = (1.0-1.9) x 10(-5) g/l; log K(ow) = 6.4-6.7; H25 = 0.0020-0.14 Pa m3/mol]. The effect of replacing a chlorine with a bromine atom significantly decreased P(o)(L,25) (log P(o)(L,25) = -0.4197 (# bromine atoms) - 2.643, p<0.01) and H25 (log H25 = -0.508 (# bromine atoms) + 0.394, p<0.02). There were no significant effects of bromine/chlorine substitution on S(w,25) or K(ow). A simple Level I equilibrium partitioning model predicted the environmental behaviour of HDBPs to be similar to a tetrabrominated diphenyl ether. Only slight differences in behaviour amongst HDBP congeners were predicted since substitution of a bromine for a chlorine (Cl/Br substitution) atom had less effect than H/Cl or H/Br substitution on P(o)(L,25), S(w,25), H25, and K(ow).

  16. Upper tropospheric water vapour and its interaction with cirrus clouds as seen from IAGOS long-term routine in-situ observations

    Science.gov (United States)

    Petzold, Andreas; Krämer, Martina; Neis, Patrick; Rolf, Christian; Rohs, Susanne; Berkes, Florian; Smit, Herman G. J.; Gallagher, Martin; Beswick, Karl; Lloyd, Gary; Baumgardner, Darrel; Spichtinger, Peter; Nédélec, Philippe; Ebert, Volker; Buchholz, Bernhard; Riese, Martin; Wahner, Andreas

    2017-04-01

    IAGOS (In-service Aircraft for a Global Observing System) performs long-term routine in-situ observations of atmospheric chemical composition (ozone, CO, NOx, NOy, CO2, CH4), water vapour, aerosols, clouds and temperature on a global scale by operating compact instruments on board of passenger aircraft. The unique characteristics of the IAGOS data set originate from the global-scale sampling on air traffic routes with similar instrumentation such that the observations are truly comparable and well suited for atmospheric research on a statistical basis. Here, we present the analysis of 15 months of simultaneous observations of relative humidity with respect to ice (RHice) and ice crystal number concentration in cirrus (Nice) from July 2014 to October 2015. The joint data set of 360 hours of RHice - Nice observations in the global upper troposphere and tropopause region is analysed with respect to the in-cloud distribution of RHice and related cirrus properties. The majority of the observed cirrus is thin with Nice < 0.1 cm-3. The respective fractions of all cloud observations range from 90% over the mid-latitude North Atlantic Ocean and the Eurasian continent to 67% over the subtropical and tropical Pacific Ocean. The in-cloud RHice distributions do not depend on the geographical region of sampling. Types of cirrus origin (in situ origin, liquid origin) are inferred for different Nice regimes and geographical regions. Most important, we found that in-cloud RHice shows a strong correlation to Nice with slightly supersaturated dynamic equilibrium RHice associated to higher Nice values in stronger updrafts.

  17. Effects of drought and changes in vapour pressure deficit on water relations of Populus deltoides growing in ambient and elevated CO2.

    Science.gov (United States)

    Bobich, Edward G; Barron-Gafford, Greg A; Rascher, Katherine G; Murthy, Ramesh

    2010-07-01

    The means by which growth CO(2) concentration ([CO(2)]) affects anatomy and water relations responses to drought and vapour pressure deficit (VPD) were studied for yearly coppiced, 4-year-old Populus deltoides clones that were grown in either 400 mumol mol(-1) (ambient) or 800 mumol mol(-1) (elevated) CO(2) for 3 years. It was hypothesized that, during drought, trees growing in elevated [CO(2)] would have a lower volume flux density of water (J(V)), stomatal conductance (g(s)) and transpiration per leaf area (E), as well as a lower stomatal density and a greater stomatal response to drought and changes in VPD than would trees in ambient [CO(2)]. Trees in elevated [CO(2)] actually had higher J(V) values throughout the study, but did not differ from trees in ambient [CO(2)] with respect to g(s) or E under saturating light or E scaled from J(V) (E(scaled)), all of which indicates that the higher J(V) in elevated [CO(2)] resulted from those trees having greater leaf area and not from differences in g(s). Furthermore, although plants in elevated [CO(2)] had greater absolute leaf loss during the drought, the percentage of leaf area lost was similar to that of trees in ambient [CO(2)]. g(s) and E under saturating light were affected by changes in VPD after the first 9 days of the experiment, which coincided with a large decrease in water potential at a soil depth of 0.1 m. Trees in elevated [CO(2)] had a greater stomatal density and a lower wood density than trees in ambient [CO(2)], both traits that may make the trees more susceptible to xylem cavitation in severe drought. Drought and VPD effects for the P. deltoides clone were not ameliorated by long-term growth in elevated [CO(2)] compared with ambient [CO(2)], and plants in elevated [CO(2)] possessed anatomical traits that may result in greater stress associated with long-term drought.

  18. Multispecies transmitter for DIAL sensing of atmospheric water vapour, methane and carbon dioxide in the 2 μm region

    Science.gov (United States)

    Mammez, Dominique; Cadiou, Erwan; Dherbecourt, Jean-Baptiste; Raybaut, Myriam; Melkonian, Jean-Michel; Godard, Antoine; Gorju, Guillaume; Pelon, Jacques; Lefebvre, Michel

    2015-10-01

    Integrated-path differential absorption lidar (IPDIAL) is an attractive technique to monitor greenhouse gases from space. For that purpose, suitable absorption lines have been identified as good candidates around 2.05 μm for CO2, 2.29 μm for CH4, and 2.06 μm for H2O. In this context, we have developed a high energy transmitter around 2 μm based on frequency conversion in a nested cavity doubly resonant optical parametric oscillator (NesCOPO) followed by high energy parametric amplification. This master oscillator power amplifier (MOPA) architecture enables the generation of tunable single-frequency high energy nanosecond pulses (tens of mJ) suitable for atmospheric DIAL applications. Moreover, taking advantage of the wide spectral coverage capability of the NesCOPO, we demonstrate the potential for this single emitter to address the aforementioned spectral lines, without the use of additional seeding devices. The emitter provides energies up to 20 mJ for the signal waves in the vicinity of CO2 and H2O lines, and 16 mJ at 2290 nm for the CH4 line. By implementing a control loop based on a wavemeter frequency measurement, the signal fluctuations can be maintained below 1 MHz rms for 10 s averaging time. Finally, from optical heterodyne analysis of the beat note between our emitter and a stabilized laser diode, the optical parametric source linewidth was estimated to be better than 60 MHz (Full width at half maximum).

  19. Stabilization of Leidenfrost vapour layer by textured superhydrophobic surfaces

    KAUST Repository

    Vakarelski, Ivan Uriev

    2012-09-12

    In 1756, Leidenfrost observed that water drops skittered on a sufficiently hot skillet, owing to levitation by an evaporative vapour film. Such films are stable only when the hot surface is above a critical temperature, and are a central phenomenon in boiling. In this so-called Leidenfrost regime, the low thermal conductivity of the vapour layer inhibits heat transfer between the hot surface and the liquid. When the temperature of the cooling surface drops below the critical temperature, the vapour film collapses and the system enters a nucleate-boiling regime, which can result in vapour explosions that are particularly detrimental in certain contexts, such as in nuclear power plants. The presence of these vapour films can also reduce liquid-solid drag. Here we show how vapour film collapse can be completely suppressed at textured superhydrophobic surfaces. At a smooth hydrophobic surface, the vapour film still collapses on cooling, albeit at a reduced critical temperature, and the system switches explosively to nucleate boiling. In contrast, at textured, superhydrophobic surfaces, the vapour layer gradually relaxes until the surface is completely cooled, without exhibiting a nucleate-boiling phase. This result demonstrates that topological texture on superhydrophobic materials is critical in stabilizing the vapour layer and thus in controlling-by heat transfer-the liquid-gas phase transition at hot surfaces. This concept can potentially be applied to control other phase transitions, such as ice or frost formation, and to the design of low-drag surfaces at which the vapour phase is stabilized in the grooves of textures without heating. © 2012 Macmillan Publishers Limited. All rights reserved.

  20. Inherent calibration of a blue LED-CE-DOAS instrument to measure iodine oxide, glyoxal, methyl glyoxal, nitrogen dioxide, water vapour and aerosol extinction in open cavity mode

    Directory of Open Access Journals (Sweden)

    R. Thalman

    2010-12-01

    Full Text Available The combination of Cavity Enhanced Absorption Spectroscopy (CEAS with broad-band light sources (e.g. Light-Emitting Diodes, LEDs lends itself to the application of cavity enhanced Differential Optical Absorption Spectroscopy (CE-DOAS to perform sensitive and selective point measurements of multiple trace gases and aerosol extinction with a single instrument. In contrast to other broad-band CEAS techniques, CE-DOAS relies only on the measurement of relative intensity changes, i.e. does not require knowledge of the light intensity in the absence of trace gases and aerosols (I0. We have built a prototype LED-CE-DOAS instrument in the blue spectral range (420–490 nm to measure nitrogen dioxide (NO2, glyoxal (CHOCHO, methyl glyoxal (CH3COCHO, iodine oxide (IO, water vapour (H2O and oxygen dimers (O4. We demonstrate the first direct detection of methyl glyoxal, and the first CE-DOAS detection of CHOCHO and IO. The instrument is further inherently calibrated for light extinction from the cavity by observing O4 or H2O (at 477 nm and 443 nm and measuring the pressure, relative humidity and temperature independently. This approach is demonstrated by experiments where laboratory aerosols of known size and refractive index were generated and their extinction measured. The measured extinctions were then compared to the theoretical extinctions calculated using Mie theory (3–7 × 10−7cm−1. Excellent agreement is found from both the O4 and H2O retrievals. This enables the first inherently calibrated CEAS measurement at blue wavelengths in open cavity mode, and eliminates the need for sampling lines to supply air to the cavity, i.e., keep the cavity enclosed and/or aerosol free. Measurements in open cavity mode are demonstrated for CHOCHO, CH3COCHO, NO2, H2O and aerosol extinction. Our prototype

  1. Optimized sampling of hydroperoxides and investigations of the water vapour dependence of hydroperoxide formation during ozonolysis of alkenes; Optimierung der Probenahme von Hydroperoxiden und Untersuchungen zur Wasserdampfabhaengigkeit der Bildung von Hydroperoxiden bei der Ozonolyse von Alkenen

    Energy Technology Data Exchange (ETDEWEB)

    Becker, K.H.; Plagens, H.

    1997-06-01

    There are several sampling methods for hydroperoxides none of which is particularly reliable. The authors therefore tested three new methods in order to optimize hydroperoxide sampling and, using the optimized sampling procedure, to investigate the water vapour dependence of hydroperoxide formation during ozonolysis of alkenes. (orig.) [Deutsch] Fuer die Probenahme von Hydroperoxiden existieren verschiedene Verfahren, von denen bisher keines als besonders zuverlaessig angesehen werden konnte. Daher wurden in dieser Arbeit drei Verfahren getestet, um die Probenahme von Hydroperoxiden zu optimieren und mit dem entsprechenden Verfahren die Wasserdampfabhaengigkeit der Bildung von Hydroperoxiden bei der Ozonolyse von Alkenen zu untersuchen. (orig.)

  2. Tritium in the food chain. Intercomparison of model predictions of contamination in soil, crops, milk and beef after a short exposure to tritiated water vapour in air

    Energy Technology Data Exchange (ETDEWEB)

    Barry, P. [PJS Barry (Canada)] [and others

    1996-09-01

    Future fusion reactors using tritium as fuel will contain large inventories of the gas. The possibility that a significant fraction of an inventory may accidentally escape into the atmosphere from this and other potential sources such as tritium handling facilities and some fission reactors e g, PWRs has to be recognized and its potential impact on local human populations and biota assessed. Tritium gas is relatively inert chemically and of low radiotoxicity but it is readily oxidized by soil organisms to the mixed oxide, HTO or tritiated water. In this form it is highly mobile, strongly reactive biologically and much more toxic. Models of how tritiated water vapour is transported through the biosphere to foodstuffs important to man are essential components of such an assessment and it is important to test the models for their suitability when used for this purpose. To evaluate such models, access to experimental measurements made after actual releases are needed. There have however, been very few accidental releases of tritiated water to the atmosphere and the experimental findings of those that have occurred have been used to develop the models under test. Models must nevertheless be evaluated before their predictions can be used to decide the acceptability or otherwise of designing and operating major nuclear facilities. To fulfil this need a model intercomparison study was carried out for a hypothetical release scenario. The study described in this report is a contribution to the development of model evaluation procedures in general as well as a description of the results of applying these procedures to the particular case of models of HTO transport in the biosphere which are currently in use or being developed. The study involved eight modelers using seven models in as many countries. In the scenario farmland was exposed to 1E10 Bq d/m{sup 3} of HTO in air during 1 hour starting at midnight in one case and at 10.00 a.m. in the other, 30 days before harvest of

  3. Measurements of Isotopic Composition of Vapour on the Antarctic Plateau

    Science.gov (United States)

    Casado, M.; Landais, A.; Masson-Delmotte, V.; Genthon, C.; Prie, F.; Kerstel, E.; Kassi, S.; Arnaud, L.; Steen-Larsen, H. C.; Vignon, E.

    2015-12-01

    The oldest ice core records are obtained on the East Antarctic plateau. The composition in stable isotopes of water (δ18O, δD, δ17O) permits to reconstruct the past climatic conditions over the ice sheet and also at the evaporation source. Paleothermometer accuracy relies on good knowledge of processes affecting the isotopic composition of surface snow in Polar Regions. Both simple models such as Rayleigh distillation and global atmospheric models with isotopes provide good prediction of precipitation isotopic composition in East Antarctica but post deposition processes can alter isotopic composition on site, in particular exchanges with local vapour. To quantitatively interpret the isotopic composition of water archived in ice cores, it is thus essential to study the continuum water vapour - precipitation - surface snow - buried snow. While precipitation and snow sampling are routinely performed in Antarctica, climatic conditions in Concordia, very cold (-55°C in average) and very dry (less than 1000ppmv), impose difficult conditions to measure the water vapour isotopic composition. New developments in infrared spectroscopy enable now the measurement of isotopic composition in water vapour traces (down to 20ppmv). Here we present the results of a campaign of measurement of isotopic composition in Concordia in 2014/2015. Two infrared spectrometers have been deployed or the first time on top of the East Antarctic Plateau allowing a continuous vapour measurement for a month. Comparison of the results from infrared spectroscopy with cryogenic trapping validates the relevance of the method to measure isotopic composition in dry conditions. Identification of different behaviour of isotopic composition in the water vapour associated to turbulent or stratified regime indicates a strong impact of meteorological processes in local vapour/snow interaction.

  4. Absorption of water vapour in the falling film of water-(LiBr + LiI + LiNO{sub 3} + LiCl) in a vertical tube at air-cooling thermal conditions

    Energy Technology Data Exchange (ETDEWEB)

    Bourouis, Mahmoud; Valles, Manel; Medrano, Marc; Coronas, Alberto [Centro de Innovacion Tecnologica en Revalorizacion Energetica y Refrigeracion, CREVER, Universitat Rovira i Virgili, Autovia de Salou, s/n, 43006, Tarragona (Spain)

    2005-05-01

    In air-cooled water-LiBr absorption chillers the working conditions in the absorber and condenser are shifted to higher temperatures and concentrations, thereby increasing the risk of crystallisation. To develop this technology, two main problems are to be addressed: the availability of new salt mixtures with wider range of solubility than water-LiBr, and advanced absorber configurations that enable to carry out simultaneously an appropriate absorption process and an effective air-cooling. One way of improving the solubility of LiBr aqueous solutions is to add other salts to create multicomponent salt solutions. The aqueous solution of the quaternary salt system (LiBr + LiI + LiNO{sub 3} + LiCl) presents favourable properties required for air-cooled absorption systems: less corrosive and crystallisation temperature about 35 K lower than that of water-LiBr.This paper presents an experimental study on the absorption of water vapour over a wavy laminar falling film of an aqueous solution of (LiBr + LiI + LiNO{sub 3} + LiCl) on the inner wall of a water-cooled smooth vertical tube. Cooling water temperatures in the range 30-45 C were selected to simulate air-cooling thermal conditions. The results are compared with those obtained in the same experimental set-up with water-LiBr solutions.The control variables for the experimental study were: absorber pressure, solution Reynolds number, solution concentration and cooling water temperature. The parameters considered to assess the absorber performance were: absorber thermal load, mass absorption flux, degree of subcooling of the solution leaving the absorber, and the falling film heat transfer coefficient.The higher solubility of the multicomponent salt solution makes possible the operation of the absorber at higher salt concentration than with the conventional working fluid water-LiBr. The absorption fluxes achieved with water-(LiBr + LiI + LiNO{sub 3} + LiCl) at a concentration of 64.2 wt% are around 60 % higher than

  5. Interactions of fission product vapours with aerosols

    Energy Technology Data Exchange (ETDEWEB)

    Benson, C.G.; Newland, M.S. [AEA Technology, Winfrith (United Kingdom)

    1996-12-01

    Reactions between structural and reactor materials aerosols and fission product vapours released during a severe accident in a light water reactor (LWR) will influence the magnitude of the radiological source term ultimately released to the environment. The interaction of cadmium aerosol with iodine vapour at different temperatures has been examined in a programme of experiments designed to characterise the kinetics of the system. Laser induced fluorescence (LIF) is a technique that is particularly amenable to the study of systems involving elemental iodine because of the high intensity of the fluorescence lines. Therefore this technique was used in the experiments to measure the decrease in the concentration of iodine vapour as the reaction with cadmium proceeded. Experiments were conducted over the range of temperatures (20-350{sup o}C), using calibrated iodine vapour and cadmium aerosol generators that gave well-quantified sources. The LIF results provided information on the kinetics of the process, whilst examination of filter samples gave data on the composition and morphology of the aerosol particles that were formed. The results showed that the reaction of cadmium with iodine was relatively fast, giving reaction half-lives of approximately 0.3 s. This suggests that the assumption used by primary circuit codes such as VICTORIA that reaction rates are mass-transfer limited, is justified for the cadmium-iodine reaction. The reaction was first order with respect to both cadmium and iodine, and was assigned as pseudo second order overall. However, there appeared to be a dependence of aerosol surface area on the overall rate constant, making the precise order of the reaction difficult to assign. The relatively high volatility of the cadmium iodide formed in the reaction played an important role in determining the composition of the particles. (author) 23 figs., 7 tabs., 22 refs.

  6. Can painted glass felt or glass fibre cloth be used as vapour barrier?

    DEFF Research Database (Denmark)

    El-Khattam, Amira; Andersen, Mie Them; Kielsgaard Hansen, Kurt

    2014-01-01

    it is essential to know how much influence a surface treatment has on the water vapour transport. Traditionally, there has been most focus on paints that affect the permeability as little as possible. However, sometimes water vapour resistance is desirable. Especially, this is relevant in existing buildings...... on the ceiling e.g. as an ordinary paint. This paper presents the results of an investigation of the water vapour resistance of surface treatments which are commonly used in-door. The water vapour resistance was measured by the cup method. Aerated concrete was investigated with and without various surface...... treatments. The surface treatments were glass felt or glass fibre cloth with different types of paints or just paint. The paint types were acrylic paint and silicate paint. The results show that the paint type has high influence on the water vapour resistance while the underlay i.e. glass felt or glass fibre...

  7. Numerical implementation and oceanographic application of the thermodynamic potentials of liquid water, water vapour, ice, seawater and humid air – Part 2: The library routines

    Directory of Open Access Journals (Sweden)

    D. G. Wright

    2010-07-01

    Full Text Available The SCOR/IAPSO1 Working Group 127 on Thermodynamics and Equation of State of Seawater has prepared recommendations for new methods and algorithms for numerical estimation of the the thermophysical properties of seawater. As an outcome of this work, a new International Thermodynamic Equation of Seawater (TEOS–10 was endorsed by IOC/UNESCO2 in June 2009 as the official replacement and extension of the 1980 International Equation of State, EOS-80. As part of this new standard a source code package has been prepared that is now made freely available to users via the World Wide Web. This package includes two libraries referred to as the SIA (Sea-Ice-Air library and the GSW (Gibbs SeaWater library. Information on the GSW library may be found on the TEOS-10 web site (http://www.TEOS-10.org. This publication provides an introduction to the SIA library which contains routines to calculate various thermodynamic properties as discussed in the companion paper. The SIA library is very comprehensive, including routines to deal with fluid water, ice, seawater and humid air as well as equilibrium states involving various combinations of these, with equivalent code developed in different languages. The code is hierachically structured in modules that support (i almost unlimited extension with respect to additional properties or relations, (ii an extraction of self-contained sub-libraries, (iii separate updating of the empirical thermodynamic potentials, and (iv code verification on different platforms and between different languages. Error trapping is implemented to identify when one or more of the primary routines are accessed significantly beyond their established range of validity. The initial version of the SIA library is available in Visual Basic and FORTRAN as a supplement to this publication and updates will be maintained on the TEOS-10 web site.

    1

  8. Numerical implementation and oceanographic application of the thermodynamic potentials of liquid water, water vapour, ice, seawater and humid air - Part 2: The library routines

    Science.gov (United States)

    Wright, D. G.; Feistel, R.; Reissmann, J. H.; Miyagawa, K.; Jackett, D. R.; Wagner, W.; Overhoff, U.; Guder, C.; Feistel, A.; Marion, G. M.

    2010-07-01

    The SCOR/IAPSO1 Working Group 127 on Thermodynamics and Equation of State of Seawater has prepared recommendations for new methods and algorithms for numerical estimation of the the thermophysical properties of seawater. As an outcome of this work, a new International Thermodynamic Equation of Seawater (TEOS-10) was endorsed by IOC/UNESCO2 in June 2009 as the official replacement and extension of the 1980 International Equation of State, EOS-80. As part of this new standard a source code package has been prepared that is now made freely available to users via the World Wide Web. This package includes two libraries referred to as the SIA (Sea-Ice-Air) library and the GSW (Gibbs SeaWater) library. Information on the GSW library may be found on the TEOS-10 web site (http://www.TEOS-10.org). This publication provides an introduction to the SIA library which contains routines to calculate various thermodynamic properties as discussed in the companion paper. The SIA library is very comprehensive, including routines to deal with fluid water, ice, seawater and humid air as well as equilibrium states involving various combinations of these, with equivalent code developed in different languages. The code is hierachically structured in modules that support (i) almost unlimited extension with respect to additional properties or relations, (ii) an extraction of self-contained sub-libraries, (iii) separate updating of the empirical thermodynamic potentials, and (iv) code verification on different platforms and between different languages. Error trapping is implemented to identify when one or more of the primary routines are accessed significantly beyond their established range of validity. The initial version of the SIA library is available in Visual Basic and FORTRAN as a supplement to this publication and updates will be maintained on the TEOS-10 web site. 1SCOR/IAPSO: Scientific Committee on Oceanic Research/International Association for the Physical Sciences of the Oceans 2

  9. Seasonal, interannual and long-term variabilities and tendencies of water vapour in the upper stratosphere and mesospheric region over tropics (30°N-30°S)

    Science.gov (United States)

    Nath, Oindrila; Sridharan, S.; Naidu, C. V.

    2018-01-01

    Tropical water vapour volume mixing ratio (WVMR) data for October 2004-September 2015 obtained from the Microwave Limb Sounder are used to study its long-term variabilities and tendencies in the height region 12.1-0.002 hPa. Above 0.01 hPa, the WVMR shows minimum March-May and September-November (∼0.7-0.8 ppmv) and maximum during June-August. It shows a large interannual variability at 31-64 km. The results from multivariate regression analysis show an increasing trend with maximum value of ∼0.045 ppmv/yr at 1.21-0.41 hPa. It shows a significant negative solar cycle response at mesospheric heights.

  10. Catalytic Conversion of Biomass Pyrolysis Vapours over Sodium-Based Catalyst; A Study on teh State of Sodium on the Catalyst

    NARCIS (Netherlands)

    Nguyen, T.S.; Lefferts, Leonardus; Gupta, K.B. Sai Sankar; Seshan, Kulathuiyer

    2015-01-01

    In situ upgrading of biomass pyrolysis vapours over Na2CO3/γ-Al2O3 catalysts was studied in a laboratory-scale fixed-bed reactor at 500 °C. Catalytic oil exhibits a significant improvement over its non-catalytic counterpart, such as lower oxygen content (12.3 wt % compared to 42.1 wt %), higher

  11. Lagrangian process attribution of isotopic variations in near-surface water vapour in a 30-year regional climate simulation over Europe

    Science.gov (United States)

    Dütsch, Marina; Pfahl, Stephan; Meyer, Miro; Wernli, Heini

    2018-02-01

    Stable water isotopes are naturally available tracers of moisture in the atmosphere. Due to isotopic fractionation, they record information about condensation and evaporation processes during the transport of air parcels, and therefore present a valuable means for studying the global water cycle. However, the meteorological processes driving isotopic variations are complex and not very well understood so far, in particular on short (hourly to daily) timescales. This study presents a Lagrangian method for attributing the isotopic composition of air parcels to meteorological processes, which provides new insight into the isotopic history of air parcels. It is based on the temporal evolution of the isotope ratios, the humidity, the temperature, and the location of the air parcels. Here these values are extracted along 7-day backward trajectories started every 6 hours from near the surface in a 30-year regional climate simulation over Europe with the isotope-enabled version of the model of the Consortium for Small-Scale Modelling (COSMOiso). The COSMOiso simulation has a horizontal resolution of 0.25° and is driven at the lateral boundaries by a T106 global climate simulation with the isotope-enabled version of the European Centre Hamburg model (ECHAMwiso). Both simulations are validated against measurements from the Global Network of Isotopes in Precipitation (GNIP), which shows that nesting COSMOiso within ECHAMwiso improves the representation of δ2H and deuterium excess in monthly accumulated precipitation. The method considers all isotopic changes that occur inside the COSMOiso model domain, which, on average, correspond to more than half of the mean and variability in both δ2H and deuterium excess at the air parcels' arrival points. Along every trajectory, the variations in the isotope values are quantitatively decomposed into eight process categories (evaporation from the ocean, evapotranspiration from land, mixing with moister air, mixing with drier air

  12. Stabilisation of Collagen Sponges by Glutaraldehyde Vapour Crosslinking

    Directory of Open Access Journals (Sweden)

    Yong Y. Peng

    2017-01-01

    Full Text Available Glutaraldehyde is a well-recognised reagent for crosslinking and stabilising collagens and other protein-based materials, including gelatine. In some cases, however, the use of solutions can disrupt the structure of the material, for example, by causing rapid dispersion or distortions from surface interactions. An alternative approach that has been explored in a number of individual cases is the use of glutaraldehyde vapour. In this study, the effectiveness of a range of different glutaraldehyde concentrations in the reservoir providing vapour, from 5% to 25% (w/v, has been explored at incubation times from 5 h to 48 h at room temperature. These data show the effectiveness of the glutaraldehyde vapour approach for crosslinking collagen and show that materials with defined, intermediate stability could be obtained, for example, to control resorption rates in vivo.

  13. Signal transduction pathway(s) in guard cells after prolonged exposure to low vapour pressure deficit

    NARCIS (Netherlands)

    Ali Niaei Fard, S.

    2014-01-01

    Keywords: Abscisic acid, Arabidopsis thaliana, calcium, CYP707As, desiccation, environmental factors, guard cells’ signalling pathway, hydrogen peroxide, natural variation, nitric oxide, photosystem II efficiency, RD29A, relative water content, secondary messengers, stomata, vapour pressure

  14. A method for the detection of alcohol vapours based on optical sensing of magnesium 5,10,15,20-tetraphenyl porphyrin thin film by an optical spectrometer and principal component analysis.

    Science.gov (United States)

    Kladsomboon, Sumana; Kerdcharoen, Teerakiat

    2012-12-13

    In this work we have proposed a method for the detection of alcohol vapours, i.e. methanol, ethanol and isopropanol, based on the optical sensing response of magnesium 5,10,15,20-tetraphenyl porphyrin (MgTPP) thin films, as measured by optical spectrometry with the assistance of chemometric analysis. We have implemented a scheme which allows a laboratory UV-vis spectrometer to act as a so-called "electronic nose" with very little modification. MgTPP thin films were prepared by a spin coating technique, using chloroform as the solvent, and then subjected to thermal annealing at 280°C in an argon atmosphere. These MgTPP optical gas sensors presented significant responses with methanol compared to ethanol and isopropanol, based on the dynamic flow of alcohol vapours at the same mol% of alcohol concentration. Density functional theory (DFT) calculations were performed to model the underlying mechanism of this selectivity. The performance of the optical gas sensors was optimised by varying the fabrication parameters. It is hoped that the MgTPP thin film together with an off-the-shelf optical spectrometer and a simple chemometrics algorithm can be a valuable tool for the analysis of alcoholic content in the beverage industry. Copyright © 2012 Elsevier B.V. All rights reserved.

  15. Spontaneuos and Parametric Processes in Warm Rubidium Vapours

    Directory of Open Access Journals (Sweden)

    Dąbrowski M.

    2014-12-01

    Full Text Available Warm rubidium vapours are known to be a versatile medium for a variety of experiments in atomic physics and quantum optics. Here we present experimental results on producing the frequency converted light for quantum applications based on spontaneous and stimulated processes in rubidium vapours. In particular, we study the efficiency of spontaneously initiated stimulated Raman scattering in the Λ-level configuration and conditions of generating the coherent blue light assisted by multi-photon transitions in the diamond-level configuration. Our results will be helpful in search for new types of interfaces between light and atomic quantum memories.

  16. Vapour-phase method in the synthesis of polymer-ibuprofen sodium-silica gel composites.

    Science.gov (United States)

    Kierys, Agnieszka; Krasucka, Patrycja; Grochowicz, Marta

    2017-11-01

    The study discusses the synthesis of polymer-silica composites comprising water soluble drug (ibuprofen sodium, IBS). The polymers selected for this study were poly(TRIM) and poly(HEMA- co -TRIM) produced in the form of permanently porous beads via the suspension-emulsion polymerization method. The acid and base set ternary composites were prepared by the saturation of the solid dispersions of drug (poly(TRIM)-IBS and/or poly(HEMA- co -TRIM)-IBS) with TEOS, and followed by their exposition to the vapour mixture of water and ammonia, or water and hydrochloric acid, at autogenous pressure. The conducted analyses reveal that the internal structure and total porosity of the resulting composites strongly depend on the catalyst which was used for silica precursor gelation. The parameters characterizing the porosity of both of the acid set composites are much lower than the parameters of the base set composites. Moreover, the basic catalyst supplied in the vapour phase does not affect the ibuprofen sodium molecules, whereas the acid one causes transformation of the ibuprofen sodium into the sodium chloride and a derivative of propanoic acid, which is poorly water soluble. The release profiles of ibuprofen sodium from composites demonstrate that there are differences in the rate and efficiency of drug desorption from them. They are mainly affected by the chemical character of the polymeric carrier but are also associated with the restricted swelling of the composites in the buffer solution after precipitation of silica gel.

  17. Effect of ZnO nanoparticles in R290/R600a (50/50) based vapour compression refrigeration system added via lubricant oil on compressor suction and discharge characteristics

    Science.gov (United States)

    Kumar, Ravinder; Singh, Jagdev

    2017-05-01

    The primary source of energy consumption in a vapour compression refrigeration system is a compressor. The possibility of a reduction in the work of compression may leads to enhance the compressor suction and discharge characteristics and the overall performance of the refrigeration system. The present experimental investigation based upon the study of ZnO nanoparticles in a vapour compression refrigeration system using hydrocarbon blend R290/R600a (50/50) as a refrigerant. The zinc oxide nanoparticles are appended with system refrigerant via compressor lubricating oil. The results observed that by using different weight concentrations of nanoparticles in R290/R600a refrigeration system, both the compressor suction and discharge pressures and temperatures were reduced compared to conventional system. The viscosity of mineral oil with the addition of nanoparticles increases. The compressor energy consumption was reduced by 7.48 % using (0.2-1.0) wt% concentrations of nanoparticles. The COP of the refrigeration system has been increased by about 46 % with the addition of nanoparticles. Thus, the ZnO nanoparticles worked efficiently in the R290/R600a refrigeration system.

  18. Modelling raster-based monthly water balance components for Europe

    Energy Technology Data Exchange (ETDEWEB)

    Ulmen, C.

    2000-11-01

    The terrestrial runoff component is a comparatively small but sensitive and thus significant quantity in the global energy and water cycle at the interface between landmass and atmosphere. As opposed to soil moisture and evapotranspiration which critically determine water vapour fluxes and thus water and energy transport, it can be measured as an integrated quantity over a large area, i.e. the river basin. This peculiarity makes terrestrial runoff ideally suited for the calibration, verification and validation of general circulation models (GCMs). Gauging stations are not homogeneously distributed in space. Moreover, time series are not necessarily continuously measured nor do they in general have overlapping time periods. To overcome this problems with regard to regular grid spacing used in GCMs, different methods can be applied to transform irregular data to regular so called gridded runoff fields. The present work aims to directly compute the gridded components of the monthly water balance (including gridded runoff fields) for Europe by application of the well-established raster-based macro-scale water balance model WABIMON used at the Federal Institute of Hydrology, Germany. Model calibration and validation is performed by separated examination of 29 representative European catchments. Results indicate a general applicability of the model delivering reliable overall patterns and integrated quantities on a monthly basis. For time steps less then too weeks further research and structural improvements of the model are suggested. (orig.)

  19. Environmental and Physiographic Controls on Inter-Growing Season Variability of Carbon Dioxide and Water Vapour Fluxes in a Minerotrophic Fen

    Science.gov (United States)

    van der Kamp, G.; Sonnentag, O.; Chen, J. M.; Barr, A.; Hedstrom, N.; Granger, R.

    2008-12-01

    The interaction of fens with groundwater is spatially and temporally highly variable in response to meteorological conditions, resulting in frequent changes of groundwater fluxes in both vertical and lateral directions (flow reversals) across the mineral soil-peat boundary. However, despite the importance of the topographic and hydrogeological setting of fens, no study has been reported in the literature that explores a fen's atmospheric CO2 and energy flux densities under contrasting meteorological conditions in response to its physiographic setting. In our contribution we report four years of growing season eddy covariance and supporting measurements from the Canada Fluxnet-BERMS fen (formerly BOREAS southern peatland) in Saskatchewan, Canada. We first analyze hydrological data along two piezometer transects across the mineral soil-peat boundary with the objective of assessing changes in water table configuration and thus hydraulic gradients, indicating flow reversals, in response to dry and wet meteorological conditions. Next we quantify and compare growing season totals and diurnal and daily variations in evapotranspiration (ET) and net ecosystem exchange (NEE) and its component fluxes gross ecosystem productivity (GPP) and terrestrial ecosystem respiration (TER) to identify their controls with a major focus on water table depth. While ET growing season totals were similar (~ 310 mm) under dry and wet meteorological conditions, the CO2 sink- source strength of Sandhill fen varied substantially from carbon neutral (NEE = -2 [+-7] g C m-2 per growing season) under dry meteorological condition (2003) to a moderate CO2- sink with NEE ranging between 157 [+- 10] and 190 [+- 11] g C m-2 per growing season under wet meteorological conditions (2004, 2005, and 2006). Using a process-oriented ecosystem model, BEPS-TerrainLab, we investigate how different canopy components at Sandhill contribute to total ET and GPP, and thus water use efficiency, under dry and wet

  20. Gas and vapour detection using polypyrrole

    NARCIS (Netherlands)

    Leur, R.H.M. van de; Waal, A. van der

    1999-01-01

    The vapours of organic solvents like toluene, butanon, and ethanol do effect the electrical conductivity of electrochemically synthesised polypyrrole. This property allows the use of polypyrrole in sensors for vapour detection. The conductivity is also a function of temperature and the history of

  1. Numerical implementation and oceanographic application of the thermodynamic potentials of water, vapour, ice, seawater and air - Part 2: The library routines

    Science.gov (United States)

    Wright, D. G.; Feistel, R.; Reissmann, J. H.; Miyagawa, K.; Jackett, D. R.; Wagner, W.; Overhoff, U.; Guder, C.; Feistel, A.; Marion, G. M.

    2010-03-01

    The SCOR/IAPSO1 Working Group 127 on Thermodynamics and Equation of State of Seawater has prepared recommendations for new methods and algorithms for numerical estimation of the thermophysical properties of seawater. As an outcome of this work, a new International Thermodynamic Equation of Seawater (TEOS-10) was endorsed by IOC/UNESCO2 in June 2009 as the official replacement and extension of the 1980 International Equation of State, EOS-80. As part of this new standard a source code package has been prepared that is now made freely available to users via the World Wide Web. This package includes two libraries referred to as the SIA (Sea-Ice-Air) library and the GSW (Gibbs SeaWater) library. Information on the GSW library may be found on the TEOS-10 web site (http://www.TEOS-10.org). This publication provides an introduction to the SIA library which contains routines to calculate various thermodynamic properties as discussed in the companion paper. The SIA library is very comprehensive, including routines to deal with fluid water, ice, seawater and humid air as well as equilibrium states involving various combinations of these, with equivalent code developed in different languages. The code is hierachically structured in modules that support (i) almost unlimited extension with respect to additional properties or relations, (ii) an extraction of self-contained sub-libraries, (iii) separate updating of the empirical thermodynamic potentials, and (iv) code verification on different platforms and between different languages. Error trapping is implemented to identify when one or more of the primary routines are accessed significantly beyond their established range of validity. The initial version of the SIA library is available in Visual Basic and FORTRAN as a supplement to this publication and updates will be maintained on the TEOS-10 web site. 1 SCOR/IAPSO: Scientific Committee on Oceanic Research/International Association for the Physical Sciences of the Oceans 2 IOC

  2. Experimental test of methods for detecting water vapour penetration in sodium during operation of Czechoslovak modular 30 MW steam generator with BOR 60

    Energy Technology Data Exchange (ETDEWEB)

    Matal, O.; Sobotka, J.; Banovec, J. (Vyzkumny Ustav Zavodu Energetickeho Strojirenstvi, Brno-Slatina (Czechoslovakia))

    1983-05-01

    The Czechoslovak modular 30 MW steam generator was installed on the BOR 60 experimental reactor with the aim of testing the consequences of water penetration into liquid sodium, refining hydrodynamic and temperature reaction characteristics and testing various types of accident protection. The experiments proved that changes resulting from small steam penetration into sodium have a stochastic character. From the alarm signals from the individual detectors of the accident protection system it will be necessary to select and accurately define those signals which differ sufficiently from the actual noise of the steam generator, i.e., to make a technical and economic optimization of diagnostic systems. Various types of alarm signals were tested: the measurement of hydrogen and oxygen concentrations using a wide range of instruments, the processing of the vibroacoustic spectrum by accelerometers and other apparatus, the measurement of fluctuations of sodium flow, the pulse-noise method, the method of measuring magnetic induction during the flow of the two-phase mixture through the pipes, etc.

  3. Repetitively pulsed VUV emitter pumped by a barrier discharge in a mixture of helium with heavy water (D{sub 2}O) vapour

    Energy Technology Data Exchange (ETDEWEB)

    Shuaibov, Aleksandr K; Minya, A I; Hrytsak, R V; Gomoki, Z T; Shevera, Igor' V [Uzhgorod National University, Uzhgorod (Ukraine)

    2012-08-31

    A gas-discharge lamp based on a barrier discharge in a He - D{sub 2}O mixture at partial pressures p{sub D2O} = 0.04 - 0.33 kPa and p{sub He} = 10 - 60 kPa is studied. The emission spectrum of the discharge plasma contains mainly the A {yields} X and C {yields} X bands of OD hydroxyl ({lambda} = 144 - 160 nm). The intensities of these bands are optimised by varying the pressure and composition of working mixtures. (laser applications and other topics in quantum electronics)

  4. Surface plasmon resonance sensor based on golden nanoparticles and cold vapour generation technique for the detection of mercury in aqueous samples

    Science.gov (United States)

    Castillo, Jimmy; Chirinos, José; Gutiérrez, Héctor; La Cruz, Marie

    2017-09-01

    In this work, a surface plasmon resonance sensor for determination of Hg based on golden nanoparticles was developed. The sensor follows the change of the signal from solutions in contact with atomic mercury previously generated by the reaction with sodium borohydride. Mie theory predicts that Hg film, as low as 5 nm, induced a significant reduction of the surface plasmon resonance signal of 40 nm golden nanoparticles. This property was used for quantification purposes in the sensor. The device provide limits of detection of 172 ng/L that can compared with the 91 ng/L obtained with atomic fluorescence, a common technique used for Hg quantification in drinking water. This result was relevant, considering that it was not necessary to functionalize the nanoparticles or use nanoparticles deposited in a substrate. Also, thanks that Hg is released from the matrix, the surface plasmon resonance signal was not affected by concomitant elements in the sample.

  5. Autonomous Chemical Vapour Detection by Micro UAV

    Directory of Open Access Journals (Sweden)

    Kent Rosser

    2015-12-01

    Full Text Available The ability to remotely detect and map chemical vapour clouds in open air environments is a topic of significant interest to both defence and civilian communities. In this study, we integrate a prototype miniature colorimetric chemical sensor developed for methyl salicylate (MeS, as a model chemical vapour, into a micro unmanned aerial vehicle (UAV, and perform flights through a raised MeS vapour cloud. Our results show that that the system is capable of detecting MeS vapours at low ppm concentration in real-time flight and rapidly sending this information to users by on-board telemetry. Further, the results also indicate that the sensor is capable of distinguishing “clean” air from “dirty”, multiple times per flight, allowing us to look towards autonomous cloud mapping and source localization applications. Further development will focus on a broader range of integrated sensors, increased autonomy of detection and improved engineering of the system.

  6. The importance of the poikilohydric nature of lichens as natural tracers for delta18O of ambient vapour

    Science.gov (United States)

    Hartard, Britta; Cuntz, Matthias; Lakatos, Michael; Máguas, Cristina

    2010-05-01

    The stable isotope composition of water is routinely used as a tracer to study water exchange processes in vascular plants and ecosystems. To date, no study has focussed on isotope processes in poikilohydric organisms (i.e. lichens and bryophytes), where relative water content equilibrate with the surrounding humidity conditions and that are able to use distinct water sources such as precipitation, dew, fog and also water vapour. Moreover, lichens are ubiquitous organisms, and on a global scale, they are found in nearly all terrestrial ecosystems and also within these ecosystems they inhabit many microhabitats. As poikilohydric. especially green algal lichens are known to photosynthetically reactivate solely upon uptake of atmospheric moisture, even at non-saturated ambient humidity conditions. To understand basic isotope exchange processes on non-vascular plants, thallus water isotopic composition was studied in various green-algal lichens exposed to desiccation. The study indicates that lichens equilibrates with the isotopic composition of surrounding water vapour. We found that the thallus water of lichens exposed to high relative humidity shows fast isotopic equilibration with the surrounding vapour regardless of whether the lichen experiences water loss or vapour uptake. The time until isotopic equilibrium is achieved depends on the initial water status as well as on the lichen's specific morphology. It ranged from 5 to 12h in previously dried lichens to approximately 40h in lichens previously rehydrated with liquid water of distinct isotopic composition. Even though markedly slower, isotopic equilibration between leaf water and ambient vapour may also occur in homoiohydric plants exposed to high relative humidity. At low relative humidity, however, the apparent vapour pressure deficit between the evaporative sites and the ambient air and the increased stomatal diffusion resistance generally causes leaf water enrichment. In contrast, poikilohydric lichens lack

  7. Influence of heat consumers distribution and flashing vapours effect on steam consumption of evaporation plant of sugar factory

    National Research Council Canada - National Science Library

    A. A. Gromkovskii

    2016-01-01

    The article considered the influence of the heat consumers distribution and the flashing vapours effect juice for multipleevaporator sugar factory on the consumption the main production flow of heat transfer agent – water vapor...

  8. Giant spin Hall effect in graphene grown by chemical vapour deposition

    OpenAIRE

    Balakrishnan, Jayakumar; Koon, Gavin Kok Wai; Avsar, Ahmet; Ho, Yuda; Lee, Jong Hak; Jaiswal, Manu; Baeck, Seung Jae; Ahn, Jong Hyun; Ferreira, Aires; Cazalilla, Miguel A.; Neto, Antonio H Castro; Özyilmaz, Barbaros

    2014-01-01

    Advances in large-area graphene synthesis via chemical vapour deposition on metals like copper were instrumental in the demonstration of graphene-based novel, wafer-scale electronic circuits and proof-of-concept applications such as flexible touch panels. Here, we show that graphene grown by chemical vapour deposition on copper is equally promising for spintronics applications. In contrast to natural graphene, our experiments demonstrate that chemically synthesized graphene has a strong spin-...

  9. GNSS troposphere tomography based on two-step reconstructions using GPS observations and COSMIC profiles

    Directory of Open Access Journals (Sweden)

    P. Xia

    2013-10-01

    Full Text Available Traditionally, balloon-based radiosonde soundings are used to study the spatial distribution of atmospheric water vapour. However, this approach cannot be frequently employed due to its high cost. In contrast, GPS tomography technique can obtain water vapour in a high temporal resolution. In the tomography technique, an iterative or non-iterative reconstruction algorithm is usually utilised to overcome rank deficiency of observation equations for water vapour inversion. However, the single iterative or non-iterative reconstruction algorithm has their limitations. For instance, the iterative reconstruction algorithm requires accurate initial values of water vapour while the non-iterative reconstruction algorithm needs proper constraint conditions. To overcome these drawbacks, we present a combined iterative and non-iterative reconstruction approach for the three-dimensional (3-D water vapour inversion using GPS observations and COSMIC profiles. In this approach, the non-iterative reconstruction algorithm is first used to estimate water vapour density based on a priori water vapour information derived from COSMIC radio occultation data. The estimates are then employed as initial values in the iterative reconstruction algorithm. The largest advantage of this approach is that precise initial values of water vapour density that are essential in the iterative reconstruction algorithm can be obtained. This combined reconstruction algorithm (CRA is evaluated using 10-day GPS observations in Hong Kong and COSMIC profiles. The test results indicate that the water vapor accuracy from CRA is 16 and 14% higher than that of iterative and non-iterative reconstruction approaches, respectively. In addition, the tomography results obtained from the CRA are further validated using radiosonde data. Results indicate that water vapour densities derived from the CRA agree with radiosonde results very well at altitudes above 2.5 km. The average RMS value of their

  10. Study of the reversible water vapour sorption process of MgSO{sub 4}.7H{sub 2}O and MgCl{sub 2}.6H{sub 2}O under the conditions of seasonal solar heat storage

    Energy Technology Data Exchange (ETDEWEB)

    Ferchaud, C.J.; De Boer, R. [Eindhoven University of Technology, Department of Mechanical Engineering, Eindhoven (Netherlands); Zondag, H.A.; Veldhuis, J.B.J. [ECN Biomass and Energy Efficiency, Petten (Netherlands)

    2012-08-15

    The characterization of the structural, compositional and thermodynamic properties of MgSO{sub 4}.7H{sub 2}O and MgCl{sub 2}.6H{sub O} has been done for seasonal heat storage using in-situ X-ray Diffraction and thermal analyses (TG/DSC) under practical conditions for seasonal heat storage (T{sub max} = 150C, p(H{sub 2}O)=13 mbar). This study showed that these two materials release heat after a dehydration/hydration cycle with energy densities of 0.38 GJ/m{sup 3} for MgSO{sub 4}.7H{sub 2}O and 0.71 GJ/m{sup 3} MgCl{sub 2}.6H{sub 2}O. The low heat release found for MgSO{sub 4}.7H2O is mainly attributed to the amorphization of the material during the dehydration performed at 13 mbar which reduces its sorption capacity during the rehydration. MgCl{sub 2}.6H{sub 2}O presents a high energy density which makes this material interesting for the seasonal heat storage in domestic applications. This material would be able to fulfil the winter heat demand of a passive house estimated at 6 GJ with a packed bed reactor of 8.5 m{sup 3}. However, a seasonal heat storage system based on the water vapour sorption process in MgCl{sub 2}.6H{sub 2}O should be carefully set with a restricted temperature of 40C for the hydration reaction to avoid the liquefaction of the material at ambient temperature which limits its performances for long term storage.

  11. Silicon nanowire arrays as learning chemical vapour classifiers

    Energy Technology Data Exchange (ETDEWEB)

    Niskanen, A O; Colli, A; White, R; Li, H W; Spigone, E; Kivioja, J M, E-mail: antti.niskanen@nokia.com [Nokia Research Center, Broers Building, 21 JJ Thomson Avenue, Cambridge CB3 0FA (United Kingdom)

    2011-07-22

    Nanowire field-effect transistors are a promising class of devices for various sensing applications. Apart from detecting individual chemical or biological analytes, it is especially interesting to use multiple selective sensors to look at their collective response in order to perform classification into predetermined categories. We show that non-functionalised silicon nanowire arrays can be used to robustly classify different chemical vapours using simple statistical machine learning methods. We were able to distinguish between acetone, ethanol and water with 100% accuracy while methanol, ethanol and 2-propanol were classified with 96% accuracy in ambient conditions.

  12. Developments in vapour cloud explosion blast modeling

    NARCIS (Netherlands)

    Mercx, W.P.M.; Berg, A.C. van den; Hayhurst, C.J.; Robertson, N.J.; Moran, K.C.

    2000-01-01

    TNT Equivalency methods are widely used for vapour cloud explosion blast modeling. Presently, however, other types of models are available which do not have the fundamental objections TNT Equivalency models have. TNO Multi-Energy method is increasingly accepted as a more reasonable alternative to be

  13. Virucidal efficacy of hydrogen peroxide vapour disinfection

    NARCIS (Netherlands)

    Tuladhar, E.; Terpstra, P.; Koopmans, M.; Duizer, E.

    2012-01-01

    Background: Viral contamination of surfaces is thought to be important in transmission. Chemical disinfection can be an effective means of intervention, but little is known about the virucidal efficacy of hydrogen peroxide vapour (HPV) against enteric and respiratory viruses. Aim: To measure the

  14. Daytime Water Detection Based on Sky Reflections

    Science.gov (United States)

    Rankin, Arturo; Matthies, Larry; Bellutta, Paolo

    2011-01-01

    A water body s surface can be modeled as a horizontal mirror. Water detection based on sky reflections and color variation are complementary. A reflection coefficient model suggests sky reflections dominate the color of water at ranges > 12 meters. Water detection based on sky reflections: (1) geometrically locates the pixel in the sky that is reflecting on a candidate water pixel on the ground (2) predicts if the ground pixel is water based on color similarity and local terrain features. Water detection has been integrated on XUVs.

  15. Exploration of the phase diagram of liquid water in the low-temperature metastable region using synthetic fluid inclusions

    DEFF Research Database (Denmark)

    Qiu, Chen; Krüger, Yves; Wilke, Max

    2016-01-01

    water with a density of 0.921 kg/m3 remains in a homogeneous state during cooling down to the temperaure of −30.5 °C, where it is transformed into ice whose density corresponds to zero pressure. iii) ice melting. Ice melting temperatures of up to 6.8 °C were measured in absence of the vapour bubble, i......We present new experimental data of the low-temperature metastable region of liquid water derived from high-density synthetic fluid inclusions (996−916 kg/m3) in quartz. Microthermometric measurements include: i) Prograde (upon heating) and retrograde (upon cooling) liquid-vapour homogenisation. We...... used single ultrashort laser pulses to stimulate vapour bubble nucleation in initially monophase liquid inclusions. Water densities were calculated based on prograde homogenisation temperatures using the IAPWS-95 formulation. We found retrograde liquid-vapour homogenisation temperatures in excellent...

  16. Water Vapour Weighted Mean Temperature Model for Gps-Derived Integrated Water Vapour in Peninsular Malaysia

    Science.gov (United States)

    Musa, T. A.; Mazlan, M. H.; Opaluwa, Y. D.; Musliman, I. A.; Radzi, Z. M.

    2017-10-01

    This paper presents the development of TM model by using the radiosonde stations from Peninsular Malaysia. Two types of TM model were developed; site-specific and regional models. The result revealed that the estimation from site-specific model has small improvement compared to the regional model, indicating that the regional model is adequately to use in estimation of GPS-derived IWV over Peninsular Malaysia. Meanwhile, this study found that the diurnal cycle of TS has influenced the TM-TS relationship. The separation between daytime and nighttime observation can improve the relationship of TM-TS. However, the impact of diurnal cycle to IWV estimation is less than 1 %. The TM model from Global and Tropic also been evaluated. The Tropic TM model is superior to be utilized as compared to the Global TM model.

  17. Combustion dynamics of low vapour pressure nanofuel droplets

    Science.gov (United States)

    Pandey, Khushboo; Chattopadhyay, Kamanio; Basu, Saptarshi

    2017-07-01

    Multiscale combustion dynamics, shape oscillations, secondary atomization, and precipitate formation have been elucidated for low vapour pressure nanofuel [n-dodecane seeded with alumina nanoparticles (NPs)] droplets. Dilute nanoparticle loading rates (0.1%-1%) have been considered. Contrary to our previous studies of ethanol-water blend (high vapour pressure fuel), pure dodecane droplets do not exhibit internal boiling after ignition. However, variation in surface tension due to temperature causes shape deformations for pure dodecane droplets. In the case of nanofuels, intense heat release from the enveloping flame leads to the formation of micron-size aggregates (of alumina NPS) which serve as nucleation sites promoting heterogeneous boiling. Three boiling regimes (A, B, and C) have been identified with varying bubble dynamics. We have deciphered key mechanisms responsible for the growth, transport, and rupture of the bubbles. Bubble rupture causes ejections of liquid droplets termed as secondary atomization. Ejection of small bubbles (mode 1) resembles the classical vapour bubble collapse mechanism near a flat free surface. However, large bubbles induce severe shape deformations as well as bulk oscillations. Rupture of large bubbles results in high speed liquid jet formation which undergoes Rayleigh-Plateau tip break-up. Both modes contribute towards direct fuel transfer from the droplet surface to flame envelope bypassing diffusion limitations. Combustion lifetime of nanofuel droplets consequently has two stages: stage I (where bubble dynamics are dominant) and stage II (formation of gelatinous mass due to continuous fuel depletion; NP agglomeration). In the present work, variation of flame dynamics and spatio-temporal heat release (HR) have been analysed using high speed OH* chemiluminescence imaging. Fluctuations in droplet shape and flame heat release are found to be well correlated. Droplet flame is bifurcated in two zones (I and II). Flame response is

  18. Baseline Water Demand at Forward Operating Bases

    Science.gov (United States)

    2013-09-15

    used bottled water for drinking and teeth brushing . The base Directorate of Public Works (DPW) reported a demand of 100 Kgal/day, which translates...continue to depend on bottled water for drinking and teeth brushing , even at bases where bulk potable water is available. Observa- tions show that...a Reverse Osmosis Water Purification Unit (ROWPU), and then chlorinated. All observed bases used bottled wa- ter exclusively for drinking and teeth

  19. Stomatal sensitivity to vapour pressure deficit relates to climate of origin in Eucalyptus species.

    Science.gov (United States)

    Bourne, Aimee E; Haigh, Anthony M; Ellsworth, David S

    2015-03-01

    Selecting plantation species to balance water use and production requires accurate models for predicting how species will tolerate and respond to environmental conditions. Although interspecific variation in water use occurs, species-specific parameters are rarely incorporated into physiologically based models because often the appropriate species parameters are lacking. To determine the physiological control over water use in Eucalyptus, five stands of Eucalyptus species growing in a common garden were measured for sap flux rates and their stomatal response to vapour pressure deficit (D) was assessed. Maximal canopy conductance and whole-canopy stomatal sensitivity to D and reduced water availability were lower in species originating from more arid climates of origin than those from humid climates. Species from humid climates showed a larger decline in maximal sap flux density (JSmax) with reduced water availability, and a lower D at which stomatal closure occurred than species from more arid climates, implying larger sensitivity to water availability and D in these species. We observed significant (P < 0.05) correlations of species climate of origin with mean vessel diameter (R(2) = 0.90), stomatal sensitivity to D (R(2) = 0.83) and the size of the decline in JSmax to restricted water availability (R(2) = 0.94). Thus aridity of climate of origin appears to have a selective role in constraining water-use response among the five Eucalyptus plantation species. These relationships emphasize that within this congeneric group of species, climate aridity constrains water use. These relationships have implications for species choices for tree plantation success against drought-induced losses and the ability to manage Eucalyptus plantations against projected changes in water availability and evaporation in the future. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  20. Contribution to the activation analysis of the rare gases. Contribution to the analysis of carbon monoxide and water vapour in gases (1963); Contribution a l'analyse par activation des gaz rares. Contribution a l'analyse de l'oxyde de carbone et de la vapeur d'eau dans les gaz (1963)

    Energy Technology Data Exchange (ETDEWEB)

    Diebolt, J. [Commisariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

    1963-07-15

    In the present work, we have applied radioactive analysis to the general technique of rare gas separation. This separation is carried out on active charcoal, at constant pressure. The desorption of the gas is caused by an increase in the initial temperature of adsorption. These separations are quantitative and can be confirmed by chemical analysis. The volumes of desorbed gas are measured by radioactive counting. We have also used radioactivation to study the reduction of palladous chloride by carbon monoxide. Since this reduction is quantitative, we can have a knowledge of the mass of palladium reduced by measuring its activity. We have used the property which have organic chlorides of being hydrolysed by water vapour and of liberating hydrochloric acid to study quantitatively the amount of water vapour which a gas contains. The hydrochloric acid formed is measured by activation of the chlorine in the acid. (author) [French] Dans les travaux que nous presentons, nous avons applique l'analyse par radioactivation, a la technique generale de separation des gaz rares. Cette separation est faite sur charbon active, a pression constante. La desorption des gaz est provoquee par une augmentation de la temperature initiale d'adsorption. Ces separations sont quantitatives, et peuvent etre exploitees par l'analyse chimique. Les volumes de gaz dedorbes sont mesures par comptage de la radioactivite. Nous avons egalement utilise la radioactivation pour l'etude de la reduction du chlorure palladeux par l'oxyde de carbone. Cette reduction etant quantitative, nous pouvons connaitre la masse de palladium reduit par la mesure de son activite. Nous avons exploite la propriete que possede un chlorure organique d'etre hydrolise par la vapeur d'eau et de liberer de l'acide chlorhydrique pour etudier quantitativement la vapeur d'eau contenue dans un gaz. L'acide chlorhydrique forme est mesure par l'activation du chlore de l

  1. Water droplet condensation and evaporation in turbulent channel flow

    NARCIS (Netherlands)

    Russo, E; Kuerten, Johannes G.M.; van der Geld, C.W.M.; Geurts, Bernardus J.

    We propose a point-particle model for two-way coupling of water droplets dispersed in the turbulent flow of a carrier gas consisting of air and water vapour. We adopt an Euler–Lagrangian formulation based on conservation laws for the mass, momentum and energy of the continuous phase and on empirical

  2. Rain- vapour isotopic interaction over the south-west coast of India

    Science.gov (United States)

    Palliyil Ravisankar, Lekshmy; Madhavan, Midhun; Rengaswamy, Ramesh

    2015-04-01

    Boundary layer water vapor isotopic composition (δv) is an important factor that controls the isotopic composition of evaporation flux and modulating the δ18O of tree ring cellulose through plant physiological cycle. But due to the difficult sampling procedure for water vapor, δv has rarely been quantified. Since many simple isotopic models require δvas an input, mostly we assume that the water vapor is in isotopic equilibrium with δof monthly rain (δr). Here we present simultaneous observations of water vapour (~ 300 samples) and rainfall (~200 samples) isotopic ratios from two stations in the south-west coast of India (both the stations are located in the west of Western Ghats), sampled during April- October, 2012. Daily rain water and water vapour (cryogenic trapping method) were collected according to the IAEA protocol and the isotopic analyses (D and 18O) were done using a Thermo Fisher Delta V+ Isotope Ratio Mass Spectrometer. We observe that, water vapour and rain are close to the equilibrium values during pre monsoon (April-May, ɛ = δr - δv= 8.9 ± 1.4 ), summer monsoon (June-September, ɛ = 9.0 ± 1.8 ) and North- East (NE) monsoon (October, ɛ = 7.9 ± 2.9 ) seasons. However, some individual rain events show more deviations from the equilibrium values. NE monsoon rainfall and water vapour are isotopically more depleted in 18O compared to the pre monsoon and summer monsoon seasons, in which the depletion is more in rain (~4 ) compared to water vapour (~2 ). This is because of the 18O enrichment of ground level vapour due to local evapo- transpiration (stations are at the leeward side of the Ghats), while rainfall is directly formed from the NE monsoon clouds which is more depleted in 18O. These results will be useful for the interpretation of δ18O of tree rings from south west.

  3. Effect of Liquid/Vapour Maldistribution on the Performance of Plate Heat Exchanger Evaporators

    DEFF Research Database (Denmark)

    Jensen, Jonas Kjær; Kærn, Martin Ryhl; Ommen, Torben Schmidt

    2015-01-01

    Plate heat exchangers are often applied as evaporators in industrial refrigeration and heat pump systems. In the design and modelling of such heat exchangers the flow and liquid/vapour distribution is often assumed to be ideal. However, maldistribution may occur and will cause each channel...... to behave differently due to the variation of the mass flux and vapour quality. To evaluate the effect of maldistribution on the performance of plate heat exchangers, a numerical model is developed in which the mass, momentum and energy balances are applied individually to each channel, including suitable...... correlations for heat transfer and pressure drop. The flow distribution on both the refrigerant and secondary side is determined based on equal pressure drop while the liquid/vapour distribution is imposed to the model. Results show that maldistribution may cause up to a 25 % reduction of the overall heat...

  4. Prediction of clothing thermal insulation and moisture vapour resistance of the clothed body walking in wind.

    Science.gov (United States)

    Qian, Xiaoming; Fan, Jintu

    2006-11-01

    Clothing thermal insulation and moisture vapour resistance are the two most important parameters in thermal environmental engineering, functional clothing design and end use of clothing ensembles. In this study, clothing thermal insulation and moisture vapour resistance of various types of clothing ensembles were measured using the walking-able sweating manikin, Walter, under various environmental conditions and walking speeds. Based on an extensive experimental investigation and an improved understanding of the effects of body activities and environmental conditions, a simple but effective direct regression model has been established, for predicting the clothing thermal insulation and moisture vapour resistance under wind and walking motion, from those when the manikin was standing in still air. The model has been validated by using experimental data reported in the previous literature. It has shown that the new models have advantages and provide very accurate prediction.

  5. Numerical analysis of the interaction between high-pressure resin spray and wood chips in a vapour stream

    Directory of Open Access Journals (Sweden)

    Massimo Milani

    2016-04-01

    Full Text Available This article investigates the interaction between the resin spray and the wood chips in a vapour stream using a multi-phase multi-component computational fluid dynamics approach. The interaction between the spray and the chips is one of the main issues in the industrial process for manufacturing medium density fibre boards. Thus, the optimization of this process can lead to important benefits, such as the reduction in the emission of formaldehyde-based toxic chemicals, the reduction in energy consumption in the blending process and energy saving in the fibreboard drying process. First step of the study is the numerical analysis of the resin injector in order to extend the experimental measurements carried out with water to the resin spray. The effects of the injector’s geometrical features on the spray formation are highlighted under different injection pressure values and needle displacements. Afterwards, the results obtained in the analysis of the single injector are used for the complete simulation of multi-injector rail where the mixing of the resin spray and wood chips takes place. The influence of the main operating conditions, such as the vapour and the wood chip flow rates, on the resin distribution is addressed in order to optimize the resination process.

  6. 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

  7. Water sound recognition based on physical models

    OpenAIRE

    Guyot, Patrice; PINQUIER, Julien; André-Obrecht, Régine

    2013-01-01

    This article describes an audio signal processing algorithm to detect water sounds, built in the context of a larger system aiming to monitor daily activities of elderly people. While previous proposals for water sound recognition relied on classical machine learning and generic audio features to characterize water sounds as a flow texture, we describe here a recognition system based on a physical model of air bubble acoustics. This system is able to recognize a wide variety of water sounds a...

  8. The beauty of frost: nano-sulfur assembly via low pressure vapour deposition.

    Science.gov (United States)

    Wang, Yu; Chen, Lu; Scudiero, Louis; Zhong, Wei-Hong

    2015-11-14

    A low pressure vapour deposition (LPVD) technique is proposed as an environmentally friendly, cost-effective and versatile strategy for fabrication of sulfur nanomaterials. By controlling the characteristics of the deposit substrate for the LPVD, various sulfur-based nanomaterials have been obtained through a substrate-induced self-assembly process.

  9. An Investigation of Tertiary Students' Understanding of Evaporation, Condensation and Vapour Pressure. Research Report

    Science.gov (United States)

    Gopal, Hemant; Kleinsmidt, Jacques; Case, Jennifer; Musonge, Paul

    2004-01-01

    Based on a purposive sample of 15 second-year chemical engineering students, this study investigates students' conceptions of evaporation, condensation and vapour pressure. During individual interviews the students were questioned on three tasks that had been designed around these topics. Qualitative analysis of student responses showed a range of…

  10. An Investigation of Tertiary Students' Understanding of Evaporation, Condensation and Vapour Pressure

    Science.gov (United States)

    Gopal, Hemant; Kleinsmidt, Jacques; Case, Jennifer; Musonge, Paul

    2004-01-01

    Based on a purposive sample of 15 second-year chemical engineering students, this study investigates students' conceptions of evaporation, condensation and vapour pressure. During individual interviews the students were questioned on three tasks that had been designed around these topics. Qualitative analysis of student responses showed a range of…

  11. A computer-controlled system for generation of chemical vapours in in vitro dermal uptake studies.

    Science.gov (United States)

    Rauma, Matias; Johanson, Gunnar

    2007-02-01

    Recent work in our laboratory suggests that dermal absorption and desorption of volatile chemicals may be assessed in vitro by thermogravimetric analysis (TGA), i.e. by passing chemical vapour over a piece of skin while recording the weight increase at constant temperature and humidity. This paper describes a high-precision automated vapour-generating system for use with the TGA equipment. The system consists of computer-controlled magnetic valves and mass flow meters that split and redirect a flow of pure, dry air through different stainless-steel gas wash bottles thermostated to 25.00+/-0.05 degrees C. Each wash bottle is filled with a neat volatile chemical and designed so that the air leaving reaches 100% saturation within seconds, as shown with cyclohexanone. The air leaving the wash bottles are combined and directed via stainless-steel liners to the skin piece in the TGA chamber. The liners are heated to 30 degrees C to prevent condensation of water or chemical. Special computer software was developed to allow automatic runs with different wash bottles (chemicals) and air flows over several days. A number of measurements were made to characterize the stability and reproducibility of the vapour-generating system. We have developed a computer-controlled vapour-generating system for use in measurements of dermal absorption of chemicals by thermal gravimetry. The system has high stability and reproducibility and produces little noise.

  12. Daytime Water Detection Based on Sky Reflections

    Science.gov (United States)

    Rankin, Arturo L.; Matthies, Larry H.; Bellutta, Paolo

    2011-01-01

    Robust water detection is a critical perception requirement for unmanned ground vehicle (UGV) autonomous navigation. This is particularly true in wide-open areas where water can collect in naturally occurring terrain depressions during periods of heavy precipitation and form large water bodies. One of the properties of water useful for detecting it is that its surface acts as a horizontal mirror at large incidence angles. Water bodies can be indirectly detected by detecting reflections of the sky below the horizon in color imagery. The Jet Propulsion Laboratory (JPL) has implemented a water detector based on sky reflections that geometrically locates the pixel in the sky that is reflecting on a candidate water pixel on the ground and predicts if the ground pixel is water based on color similarity and local terrain features. This software detects water bodies in wide-open areas on cross-country terrain at mid- to far-range using imagery acquired from a forward-looking stereo pair of color cameras mounted on a terrestrial UGV. In three test sequences approaching a pond under a clear, overcast, and cloudy sky, the true positive detection rate was 100% when the UGV was beyond 7 meters of the water's leading edge and the largest false positive detection rate was 0.58%. The sky reflection based water detector has been integrated on an experimental unmanned vehicle and field tested at Ft. Indiantown Gap, PA, USA.

  13. Effect of drilling fluid systems and temperature on oil mist and vapour levels generated from shale shaker.

    Science.gov (United States)

    Steinsvåg, Kjersti; Galea, Karen S; Krüger, Kirsti; Peikli, Vegard; Sánchez-Jiménez, Araceli; Sætvedt, Esther; Searl, Alison; Cherrie, John W; van Tongeren, Martie

    2011-05-01

    Workers in the drilling section of the offshore petroleum industry are exposed to air pollutants generated by drilling fluids. Oil mist and oil vapour concentrations have been measured in the drilling fluid processing areas for decades; however, little work has been carried out to investigate exposure determinants such as drilling fluid viscosity and temperature. A study was undertaken to investigate the effect of two different oil-based drilling fluid systems and their temperature on oil mist, oil vapour, and total volatile organic compounds (TVOC) levels in a simulated shale shaker room at a purpose-built test centre. Oil mist and oil vapour concentrations were sampled simultaneously using a sampling arrangement consisting of a Millipore closed cassette loaded with glass fibre and cellulose acetate filters attached to a backup charcoal tube. TVOCs were measured by a PhoCheck photo-ionization detector direct reading instrument. Concentrations of oil mist, oil vapour, and TVOC in the atmosphere surrounding the shale shaker were assessed during three separate test periods. Two oil-based drilling fluids, denoted 'System 2.0' and 'System 3.5', containing base oils with a viscosity of 2.0 and 3.3-3.7 mm(2) s(-1) at 40°C, respectively, were used at temperatures ranging from 40 to 75°C. In general, the System 2.0 yielded low oil mist levels, but high oil vapour concentrations, while the opposite was found for the System 3.5. Statistical significant differences between the drilling fluid systems were found for oil mist (P = 0.025),vapour (P levels. Oil vapour levels at the test facility exceeded the Norwegian oil vapour occupational exposure limit (OEL) of 30 mg m(-3) when the drilling fluid temperature was ≥50°C. The practice of testing compliance of oil vapour exposure from drilling fluids systems containing base oils with viscosity of ≤2.0 mm(2) s(-1) at 40°C against the Norwegian oil vapour OEL is questioned since these base oils are very similar to white

  14. Water Detection Based on Color Variation

    Science.gov (United States)

    Rankin, Arturo L.

    2012-01-01

    This software has been designed to detect water bodies that are out in the open on cross-country terrain at close range (out to 30 meters), using imagery acquired from a stereo pair of color cameras mounted on a terrestrial, unmanned ground vehicle (UGV). This detector exploits the fact that the color variation across water bodies is generally larger and more uniform than that of other naturally occurring types of terrain, such as soil and vegetation. Non-traversable water bodies, such as large puddles, ponds, and lakes, are detected based on color variation, image intensity variance, image intensity gradient, size, and shape. At ranges beyond 20 meters, water bodies out in the open can be indirectly detected by detecting reflections of the sky below the horizon in color imagery. But at closer range, the color coming out of a water body dominates sky reflections, and the water cue from sky reflections is of marginal use. Since there may be times during UGV autonomous navigation when a water body does not come into a perception system s field of view until it is at close range, the ability to detect water bodies at close range is critical. Factors that influence the perceived color of a water body at close range are the amount and type of sediment in the water, the water s depth, and the angle of incidence to the water body. Developing a single model of the mixture ratio of light reflected off the water surface (to the camera) to light coming out of the water body (to the camera) for all water bodies would be fairly difficult. Instead, this software detects close water bodies based on local terrain features and the natural, uniform change in color that occurs across the surface from the leading edge to the trailing edge.

  15. Coupling of non-selective adsorption with selective elution for novel in-line separation and detection of cadmium by vapour generation atomic absorption spectrometry.

    Science.gov (United States)

    Zhang, Yanlin; Adeloju, Samuel B

    2015-05-01

    Non-selective adsorption of Cd(2+) ions on a cation exchange fiber and subsequent selective elution with a KI solution has been strategically utilized to develop a highly selective in-line separation of Cd(2+) ions from other metal ions for its rapid and reliable quantification by cold vapour-atomic absorption spectrometry. After retention of Cd(2+) with a high efficiency on cation exchange fiber, selective elution of the retained Cd(2+) was subsequently accomplished with 0.3M KI. Vapour generation of Cd for in-line CV-AAS determination was then achieved by merging the eluate with HCl and NaBH4. Interferences from most base metals with the vapour generation of Cd were eliminated by this approach, with the exception of Pb(2+)ions which was removed by co-precipitation with BaSO4 prior to the in-line separation. Substantial improvement in sensitivity of the in-line CV-AAS determination of Cd was achieved by increasing the sample loading time. A detection limit of 0.6 ng L(-1) (3σ) was obtained with sample loading time of 120 s, corresponding to a consumption of 24 mL of sample solution. Application of the method to the determination of Cd in certified sediment and fish samples gave a good agreement with the certified values. Further validation by recovery study in real fish sample digests and water gave average Cd recoveries of 98.7±1.0% for fish and 92±3% for water with RSD of 1.5% for fish and 4% for water, respectively. Copyright © 2015 Elsevier B.V. All rights reserved.

  16. Target Water Consumption Calculation for Human Water Management based on Water Balance

    Science.gov (United States)

    Sang, X.; Zhai, Z.; Ye, Y.; Zhai, J.

    2016-12-01

    Degradation of the regional ecological environment has become increasingly serious due to the rapid increase of water usage. Critical to water consumption management is a good approach to control the growth of water usage. Through the identification and analysis of water consumption for various sectors in the hydrosocial cycle, the method for calculating the regional target water consumption also is derived based on water balance theory. Analysis shows that during 1980 - 2004 in Tianjin City, there were 22 years in which the actual water consumption of Tianjin exceeded its target water consumption, with an average excess of 66 million m3 annually. Moreover, calculations show that the maximum human target water consumption water supply is 1.91 billion m3/a. If water consumption is controlled according to the target, the sustainable development of water resource, economic and social growth, and ecological environment in this region can be expected to be achieved.

  17. A rate equation model of stomatal responses to vapour pressure deficit and drought

    Directory of Open Access Journals (Sweden)

    Shanahan ST

    2002-08-01

    Full Text Available Abstract Background Stomata respond to vapour pressure deficit (D – when D increases, stomata begin to close. Closure is the result of a decline in guard cell turgor, but the link between D and turgor is poorly understood. We describe a model for stomatal responses to increasing D based upon cellular water relations. The model also incorporates impacts of increasing levels of water stress upon stomatal responses to increasing D. Results The model successfully mimics the three phases of stomatal responses to D and also reproduces the impact of increasing plant water deficit upon stomatal responses to increasing D. As water stress developed, stomata regulated transpiration at ever decreasing values of D. Thus, stomatal sensitivity to D increased with increasing water stress. Predictions from the model concerning the impact of changes in cuticular transpiration upon stomatal responses to increasing D are shown to conform to experimental data. Sensitivity analyses of stomatal responses to various parameters of the model show that leaf thickness, the fraction of leaf volume that is air-space, and the fraction of mesophyll cell wall in contact with air have little impact upon behaviour of the model. In contrast, changes in cuticular conductance and membrane hydraulic conductivity have significant impacts upon model behaviour. Conclusion Cuticular transpiration is an important feature of stomatal responses to D and is the cause of the 3 phase response to D. Feed-forward behaviour of stomata does not explain stomatal responses to D as feedback, involving water loss from guard cells, can explain these responses.

  18. Beam-profile monitor using a sodium-vapour

    CERN Multimedia

    1972-01-01

    Beam-profile monitor using a sodium-vapour curtain at 45 degrees to the ISR beam in Ring I (sodium generator is in white cylinder just left of centre). Electrons produced by ionization of the sodium vapour give an image of the beam on a fluorescent screen that is observed by a TV camera (at upper right).

  19. Water Detection Based on Object Reflections

    Science.gov (United States)

    Rankin, Arturo L.; Matthies, Larry H.

    2012-01-01

    Water bodies are challenging terrain hazards for terrestrial unmanned ground vehicles (UGVs) for several reasons. Traversing through deep water bodies could cause costly damage to the electronics of UGVs. Additionally, a UGV that is either broken down due to water damage or becomes stuck in a water body during an autonomous operation will require rescue, potentially drawing critical resources away from the primary operation and increasing the operation cost. Thus, robust water detection is a critical perception requirement for UGV autonomous navigation. One of the properties useful for detecting still water bodies is that their surface acts as a horizontal mirror at high incidence angles. Still water bodies in wide-open areas can be detected by geometrically locating the exact pixels in the sky that are reflecting on candidate water pixels on the ground, predicting if ground pixels are water based on color similarity to the sky and local terrain features. But in cluttered areas where reflections of objects in the background dominate the appearance of the surface of still water bodies, detection based on sky reflections is of marginal value. Specifically, this software attempts to solve the problem of detecting still water bodies on cross-country terrain in cluttered areas at low cost.

  20. Does pre-dawn water potential reflect conditions of equilibrium in plant and soil water status?

    Science.gov (United States)

    Sellin, Arne

    1999-02-01

    Variation in base water potential ( Ψb, a daily maximum level of plant water potential, which is presumed to correspond to the equilibrium between soil and plant water potentials) was examined in shoots of Picea abies and Vaccinium myrtillus with respect to soil (available water storage, water potential, temperature) and atmospheric (temperature, relative humidity, vapour pressure deficit) conditions. The available soil water storage (W tr) accounted for 77% of the dynamics of Ψb, while the influence of atmospheric factors became evident under high evaporative demand. Ψb was not always observable immediately before dawn, but on 30% of observation days, the recovery continued up to an hour or two after dawn. Full equilibrium between soil and plant water potentials in P. abies in northern conditions is rather improbable by dawn in summer-time, because of the shortness of the dark period and probable night-time transpiration in the case of high atmospheric vapour pressure deficit.

  1. Plasma Enhanced Chemical Vapour Deposition of Horizontally Aligned Carbon Nanotubes

    Directory of Open Access Journals (Sweden)

    Matthew T. Cole

    2013-05-01

    Full Text Available A plasma-enhanced chemical vapour deposition reactor has been developed to synthesis horizontally aligned carbon nanotubes. The width of the aligning sheath was modelled based on a collisionless, quasi-neutral, Child’s law ion sheath where these estimates were empirically validated by direct Langmuir probe measurements, thereby confirming the proposed reactors ability to extend the existing sheath fields by up to 7 mm. A 7 mbar growth atmosphere combined with a 25 W plasma permitted the concurrent growth and alignment of carbon nanotubes with electric fields of the order of 0.04 V μm−1 with linear packing densities of up to ~5 × 104 cm−1. These results open up the potential for multi-directional in situ alignment of carbon nanotubes providing one viable route to the fabrication of many novel optoelectronic devices.

  2. Chemical Selectivity and Sensitivity of a 16-Channel Electronic Nose for Trace Vapour Detection

    Directory of Open Access Journals (Sweden)

    Drago Strle

    2017-12-01

    Full Text Available Good chemical selectivity of sensors for detecting vapour traces of targeted molecules is vital to reliable detection systems for explosives and other harmful materials. We present the design, construction and measurements of the electronic response of a 16 channel electronic nose based on 16 differential microcapacitors, which were surface-functionalized by different silanes. The e-nose detects less than 1 molecule of TNT out of 10+12 N2 molecules in a carrier gas in 1 s. Differently silanized sensors give different responses to different molecules. Electronic responses are presented for TNT, RDX, DNT, H2S, HCN, FeS, NH3, propane, methanol, acetone, ethanol, methane, toluene and water. We consider the number density of these molecules and find that silane surfaces show extreme affinity for attracting molecules of TNT, DNT and RDX. The probability to bind these molecules and form a surface-adsorbate is typically 10+7 times larger than the probability to bind water molecules, for example. We present a matrix of responses of differently functionalized microcapacitors and we propose that chemical selectivity of multichannel e-nose could be enhanced by using artificial intelligence deep learning methods.

  3. Can painted glass felt or glass fibre cloth be used as vapour barrier?

    OpenAIRE

    El-Khattam, Amira; Andersen, Mie Them; Hansen, Kurt Kielsgaard; Møller, Eva B.

    2014-01-01

    In most Nordic homes the interior surfaces of walls and ceilings have some kind of surface treatment for aesthetical reasons. The treatments can for example be glass felt or glass fibre cloth which are painted afterwards.To evaluate the hygrothermal performance of walls and ceilings it is essential to know how much influence a surface treatment has on the water vapour transport. Traditionally, there has been most focus on paints that affect the permeability as little as possible. However, som...

  4. Influence of heat consumers distribution and flashing vapours effect on steam consumption of evaporation plant of sugar factory

    Directory of Open Access Journals (Sweden)

    A. A. Gromkovskii

    2016-01-01

    Full Text Available The article considered the influence of the heat consumers distribution and the flashing vapours effect juice for multipleevaporator sugar factory on the consumption the main production flow of heat transfer agent – water vapor. The problem of rational distribution of heat transfer agent for of the corps multiple-evaporator is relevant from point of view of energy saving and energysaving heat of the sugar factory. The solution to this problem is advantageously carried out on the basis of quantitative mathematical description of the distribution of vapor on the corps of the evaporation plant. The heat consumers distribution should be based on technical and economic calculation. To solve this problem it is advisable to use a single equation that determines the dependence of the steam flow in the first unit evaporator on the amount of evaporated water and the method of heat consumers distribution for housing. Evaporators sugar factory has two functions – technology and heat, each of which is described by its equation. On the basis of the material and heat balance equations for the realization of the basic functions of the system evaporator written multipleevaporator equations. The solution of this system allows you to obtain the equation of the steam flow and the amount of evaporated water, taking into account the flashing vapours effect. Solution of the system should take into account the accepted design standards of sugar factories. As a result of solving the system of equation is obtained, which allows you to organize and optimize the heat consumers distribution of the corps evaporator. The equation can be used for any number of units evaporator. This equation allows you to assess the efficiency of the evaporation plant of a sugar factory. This is of great practical importance in the modernization of thermal schemes of sugar factories.

  5. Risk-based water resources planning: Coupling water allocation and water quality management under extreme droughts

    Science.gov (United States)

    Mortazavi-Naeini, M.; Bussi, G.; Hall, J. W.; Whitehead, P. G.

    2016-12-01

    The main aim of water companies is to have a reliable and safe water supply system. To fulfil their duty the water companies have to consider both water quality and quantity issues and challenges. Climate change and population growth will have an impact on water resources both in terms of available water and river water quality. Traditionally, a distinct separation between water quality and abstraction has existed. However, water quality can be a bottleneck in a system since water treatment works can only treat water if it meets certain standards. For instance, high turbidity and large phytoplankton content can increase sharply the cost of treatment or even make river water unfit for human consumption purposes. It is vital for water companies to be able to characterise the quantity and quality of water under extreme weather events and to consider the occurrence of eventual periods when water abstraction has to cease due to water quality constraints. This will give them opportunity to decide on water resource planning and potential changes to reduce the system failure risk. We present a risk-based approach for incorporating extreme events, based on future climate change scenarios from a large ensemble of climate model realisations, into integrated water resources model through combined use of water allocation (WATHNET) and water quality (INCA) models. The annual frequency of imposed restrictions on demand is considered as measure of reliability. We tested our approach on Thames region, in the UK, with 100 extreme events. The results show increase in frequency of imposed restrictions when water quality constraints were considered. This indicates importance of considering water quality issues in drought management plans.

  6. Health Benefits of Water-based Exercise

    Science.gov (United States)

    ... Pools Operating Public Hot Tubs/Spas Recommendations for Hydrotherapy Tanks Preventing Pool Chemical-Associated Health Events Chloramines & ... arthritis have more health improvements after participating in hydrotherapy than with other activities 8 . Water-based exercise ...

  7. The ground-based FTIR network's potential for investigating the atmospheric water cycle

    Directory of Open Access Journals (Sweden)

    M. Schneider

    2010-04-01

    Full Text Available We present tropospheric H216O and HD16O/H216O vapour profiles measured by ground-based FTIR (Fourier Transform Infrared spectrometers between 1996 and 2008 at a northern hemispheric subarctic and subtropical site (Kiruna, Northern Sweden, 68° N and Izaña, Tenerife Island, 28° N, respectively. We compare these measurements to an isotope incorporated atmospheric general circulation model (AGCM. If the model is nudged towards meteorological fields of reanalysis data the agreement is very satisfactory on time scales ranging from daily to inter-annual. Taking the Izaña and Kiruna measurements as an example we document the FTIR network's unique potential for investigating the atmospheric water cycle. At the subarctic site we find strong correlations between the FTIR data, on the one hand, and the Arctic Oscillation index and the northern Atlantic sea surface temperature, on the other hand. The Izaña FTIR measurements reveal the importance of the Hadley circulation and the Northern Atlantic Oscillation index for the subtropical middle/upper tropospheric water balance. We document where the AGCM is able to capture these complexities of the water cycle and where it fails.

  8. GPR-Based Water Leak Models in Water Distribution Systems

    Directory of Open Access Journals (Sweden)

    David Ayala–Cabrera

    2013-11-01

    Full Text Available This paper addresses the problem of leakage in water distribution systems through the use of ground penetrating radar (GPR as a nondestructive method. Laboratory tests are performed to extract features of water leakage from the obtained GPR images. Moreover, a test in a real-world urban system under real conditions is performed. Feature extraction is performed by interpreting GPR images with the support of a pre-processing methodology based on an appropriate combination of statistical methods and multi-agent systems. The results of these tests are presented, interpreted, analyzed and discussed in this paper.

  9. Medical cannabis use in Canada: vapourization and modes of delivery

    Directory of Open Access Journals (Sweden)

    Samantha Shiplo

    2016-10-01

    Full Text Available Abstract Background The mode of medical cannabis delivery—whether cannabis is smoked, vapourized, or consumed orally—may have important implications for its therapeutic efficacy and health risks. However, there is very little evidence on current patterns of use among Canadian medical cannabis users, particularly with respect to modes of delivery. The current study examined modes of medical cannabis delivery following regulatory changes in 2014 governing how Canadians access medical cannabis. Methods A total of 364 approved adult Canadian medical cannabis users completed an online cross-sectional survey between April and June 2015. The survey examined patterns of medical cannabis use, modes of delivery used, and reasons for use. Participants were recruited through a convenience sample from nine Health Canada licensed producers. Results Using a vapourizer was the most popular mode of delivery for medical cannabis (53 %, followed by smoking a joint (47 %. The main reason for using a vapourizer was to reduce negative health consequences associated with smoking. A majority of current vapourizer users reported using a portable vapourizer (67.2 %, followed by a stationary vapourizer (41.7 %, and an e-cigarette or vape pen (19.3 %. Current use of a vapourizer was associated with fewer respiratory symptoms (AOR = 1.28, 95 % CI 1.05–1.56, p = 0.01. Conclusions The findings suggest an increase in the popularity of vapourizers as the primary mode of delivery among approved medical users. Using vapourizers has the potential to prevent some of the adverse respiratory health consequences associated with smoking and may serve as an effective harm reduction method. Monitoring implications of such current and future changes to medical cannabis regulations may be beneficial to policymakers.

  10. Nanotechnology-based water treatment strategies.

    Science.gov (United States)

    Kumar, Sandeep; Ahlawat, Wandit; Bhanjana, Gaurav; Heydarifard, Solmaz; Nazhad, Mousa M; Dilbaghi, Neeraj

    2014-02-01

    The most important component for living beings on the earth is access to clean and safe drinking water. Globally, water scarcity is pervasive even in water-rich areas as immense pressure has been created by the burgeoning human population, industrialization, civilization, environmental changes and agricultural activities. The problem of access to safe water is inevitable and requires tremendous research to devise new, cheaper technologies for purification of water, while taking into account energy requirements and environmental impact. This review highlights nanotechnology-based water treatment technologies being developed and used to improve desalination of sea and brackish water, safe reuse of wastewater, disinfection and decontamination of water, i.e., biosorption and nanoadsorption for contaminant removal, nanophotocatalysis for chemical degradation of contaminants, nanosensors for contaminant detection, different membrane technologies including reverse osmosis, nanofiltration, ultrafiltration, electro-dialysis etc. This review also deals with the fate and transport of engineered nanomaterials in water and wastewater treatment systems along with the risks associated with nanomaterials.

  11. Nanocellulose-Based Materials for Water Purification

    OpenAIRE

    Hugo Voisin; Lennart Bergström; Peng Liu; Mathew, Aji P.

    2017-01-01

    Nanocellulose is a renewable material that combines a high surface area with high strength, chemical inertness, and versatile surface chemistry. In this review, we will briefly describe how nanocellulose is produced, and present?in particular, how nanocellulose and its surface modified versions affects the adsorption behavior of important water pollutants, e.g., heavy metal species, dyes, microbes, and organic molecules. The processing of nanocellulose-based membranes and filters for water pu...

  12. Evaluation of niobium dimethylamino-ethoxide for chemical vapour deposition of niobium oxide thin films

    Energy Technology Data Exchange (ETDEWEB)

    Dabirian, Ali [Laboratory for Photonic Materials and Characterization, Ecole Polytechnique Fédérale de Lausanne (EPFL), Station 17, 1015 Lausanne (Switzerland); Kuzminykh, Yury, E-mail: yury.kuzminykh@empa.ch [Laboratory for Photonic Materials and Characterization, Ecole Polytechnique Fédérale de Lausanne (EPFL), Station 17, 1015 Lausanne (Switzerland); Laboratory for Advanced Materials Processing, Empa, Swiss Federal Laboratories for Materials Science and Technology, Feuerwerkerstrasse 39, 3602 Thun (Switzerland); Wagner, Estelle; Benvenuti, Giacomo [3D-Oxides, 70 Rue G. Eiffel Technoparc, 01630 St Genis Pouilly (France); ABCD Technology, 12 route de Champ-Colin, 1260 Nyon (Switzerland); Rushworth, Simon [Tyndall National Institute, Lee Maltings, Dyke Parade, Cork (Ireland); Hoffmann, Patrik, E-mail: patrik.hoffmann@empa.ch [Laboratory for Photonic Materials and Characterization, Ecole Polytechnique Fédérale de Lausanne (EPFL), Station 17, 1015 Lausanne (Switzerland); Laboratory for Advanced Materials Processing, Empa, Swiss Federal Laboratories for Materials Science and Technology, Feuerwerkerstrasse 39, 3602 Thun (Switzerland)

    2014-11-28

    Chemical vapour deposition (CVD) processes depend on the availability of suitable precursors. Precursors that deliver a stable vapour pressure are favourable in classical CVD processes, as they ensure process reproducibility. In high vacuum CVD (HV-CVD) process vapour pressure stability of the precursor is of particular importance, since no carrier gas assisted transport can be used. The dimeric Nb{sub 2}(OEt){sub 10} does not fulfil this requirement since it partially dissociates upon heating. Dimethylamino functionalization of an ethoxy ligand of Nb(OEt){sub 5} acts as an octahedral field completing entity and leads to Nb(OEt){sub 4}(dmae). We show that Nb(OEt){sub 4}(dmae) evaporates as monomeric molecule and ensures a stable vapour pressure and, consequently, stable flow. A set of HV-CVD experiments were conducted using this precursor by projecting a graded molecular beam of the precursor onto the substrate at deposition temperatures from 320 °C to 650 °C. Film growth rates ranging from 8 nm·h{sup −1} to values larger than 400 nm·h{sup −1} can be obtained in this system illustrating the high level of control available over the film growth process. Classical CVD limiting conditions along with the recently reported adsorption–reaction limited conditions are observed and the chemical composition, and microstructural and optical properties of the films are related to the corresponding growth regime. Nb(OEt){sub 4}(dmae) provides a large process window of deposition temperatures and precursor fluxes over which carbon-free and polycrystalline niobium oxide films with growth rates proportional to precursor flux are obtained. This feature makes Nb(OEt){sub 4}(dmae) an attractive precursor for combinatorial CVD of niobium containing complex oxide films that are finding an increasing interest in photonics and photoelectrochemical water splitting applications. The adsorption–reaction limited conditions provide extremely small growth rates comparable to an

  13. Filtering of oil vapours. Oelfrei lautet die Parole

    Energy Technology Data Exchange (ETDEWEB)

    Goehringer, P.

    1992-07-20

    Air filters are used for removing oil vapours and protecing the respiratory tract. There are centralized solutions such as cyclones side by side with individually mounted filters with casings. (orig.)

  14. Development of green vapour corrosion inhibitor

    Science.gov (United States)

    Asmara, Y. P.; Suraj, V.; Siregar, J. P.; Kurniawan, T.; Bachtiar, D.; Mohamed, N. M. Z. N.

    2017-10-01

    Corrosion control using inhibitor is an effective method to protect carbon steel from corrosion. Due to environmental toxicity of chemical inorganic corrosion inhibitors (synthetic), green inhibitors are potentially to develop. In atmospheric conditions, green vapour corrosion inhibitors are the best solutions to replace the uses of inorganic corrosion inhibitors. This research used chemical acid extraction from the key lime (citrus aurantiifolia) leaves and seeds. They are used as the main ingredients to produce this effective green corrosion inhibitor. The experiments investigated effects of corrosion inhibition on corrosion rate of low carbon steel in 3% NaCl solution using both fog salt chamber and electrochemical cell. Using salt fog chamber to represent atmospheric conditions, and corrosion rates are evaluated visually and calculated using weight loss methods. Corrosion rate on electrochemical cell were calculated using linear polarization resistance (LPR) methods. All of the experiments were set in natural conditions at pH 7. Using weight loss for three days exposure time, the efficiency of the inhibitor reached 82.39%.

  15. Vapour galvanizing (Sherardizing) of copper with zinc

    Energy Technology Data Exchange (ETDEWEB)

    Wortelen, Dietbert; Bracht, Hartmut [Westfaelische Wilhelms-Universitaet Muenster (Germany); Natrup, Frank; Graf, Wolfram [Bodycote Waermebehandlung GmbH, Sprockhoevel (Germany)

    2010-07-01

    Using a vapour galvanizing technique called Sherardizing we investigated the growth kinetics and coefficients of zinc copper phases. For this purpose polished (OFHC)-copper plates and zinc powder have been sealed in quartz ampoules under inert gas atmospheres and annealed at a temperature range between 300 and 410 C. In order to study the coating thickness and the phase composition, cross sections were prepared, which have been analyzed by means of optical microscopy and scanning electron microscopy. We were able to demonstrate that the coating thickness is a function of the parabolic time law and that the formed coatings are composed of two layers referring to the ordered {beta}-CuZn and {gamma}-Cu{sub 5}Zn{sub 8}-phases. To enhance the coating quality, small amounts of ZnCl{sub 2} were added to the zinc powder. It was observed that the coating thickness decreased with increasing ZnCl{sub 2}. Experiments with variable Ar-pressure demonstrated a reduced coating growth with increasing pressures. Further measurements with ZnCl{sub 2} were performed to check whether an electrochemical mechanism is involved in the coating process.

  16. Landmine Detection Technologies to TraceExplosive Vapour Detection Techniques

    OpenAIRE

    J. C. Kapoor; G. K. Kannan

    2007-01-01

    Large quantity of explosive is manufactured worldwide for use in various types of ammunition,arms, and mines, and used in armed conflicts. During manufacturing and usage of the explosiveequipment, some of the explosive residues are released into the environment in the form ofcontaminated effluents, unburnt explosives fumes and vapours. Limited but uncontrolledcontinuous release of trace vapours also takes place when explosive-laden landmines are deployedin the field. One of the major technolo...

  17. Aerosol assisted chemical vapour deposition of gas sensitive SnO2 and Au-functionalised SnO2 nanorods via a non-catalysed vapour solid (VS) mechanism

    Science.gov (United States)

    Vallejos, Stella; Selina, Soultana; Annanouch, Fatima Ezahra; Gràcia, Isabel; Llobet, Eduard; Blackman, Chris

    2016-01-01

    Tin oxide nanorods (NRs) are vapour synthesised at relatively lower temperatures than previously reported and without the need for substrate pre-treatment, via a vapour-solid mechanism enabled using an aerosol-assisted chemical vapour deposition method. Results demonstrate that the growth of SnO2 NRs is promoted by a compression of the nucleation rate parallel to the substrate and a decrease of the energy barrier for growth perpendicular to the substrate, which are controlled via the deposition conditions. This method provides both single-step formation of the SnO2 NRs and their integration with silicon micromachined platforms, but also allows for in-situ functionalization of the NRs with gold nanoparticles via co-deposition with a gold precursor. The functional properties are demonstrated for gas sensing, with microsensors using functionalised NRs demonstrating enhanced sensing properties towards H2 compared to those based on non-functionalised NRs. PMID:27334232

  18. Protection of historical lead against acetic acid vapour

    Directory of Open Access Journals (Sweden)

    Pecenová Z.

    2016-03-01

    Full Text Available Historical lead artefacts (small figurines, appliques, bull (metal seal can be stored in depository and archives in inconvenient storage conditions. The wooden show-case or paper packagings release volatile organic compound to the air during their degradation. These acids, mainly acetic acid are very corrosive for lead. The thin layer of corrosion products which slows atmospheric corrosion is formed on lead surface in atmospheric condition. In presence of acetic acid vapour the voluminous corrosion products are formed and fall off the surface. These corrosion products do not have any protection ability. The lead could be protected against acid environment by layer of “metal soup” which is formed on surface after immersion in solution of salt of carboxylic acid for 24 hours. The solutions of acids (with vary long of carbon chain and their salts are examined. Longer carbon chain provides better efficiency convers layer. The disadvantages are low solubility of carboxylic acids in water and bad abrasion resistance of formed layer.

  19. Exploration of the phase diagram of liquid water in the low-temperature metastable region using synthetic fluid inclusions.

    Science.gov (United States)

    Qiu, C; Krüger, Y; Wilke, M; Marti, D; Rička, J; Frenz, M

    2016-10-12

    We present new experimental data of the low-temperature metastable region of liquid water derived from high-density synthetic fluid inclusions (996-916 kg m-3) in quartz. Microthermometric measurements include: (i) prograde (upon heating) and retrograde (upon cooling) liquid-vapour homogenisation. We used single ultrashort laser pulses to stimulate vapour bubble nucleation in initially monophase liquid inclusions. Water densities were calculated based on prograde homogenisation temperatures using the IAPWS-95 formulation. We found retrograde liquid-vapour homogenisation temperatures in excellent agreement with IAPWS-95. (ii) Retrograde ice nucleation. Raman spectroscopy was used to determine the nucleation of ice in the absence of the vapour bubble. Our ice nucleation data in the doubly metastable region are inconsistent with the low-temperature trend of the spinodal predicted by IAPWS-95, as liquid water with a density of 921 kg m-3 remains in a homogeneous state during cooling down to a temperature of -30.5 °C, where it is transformed into ice whose density corresponds to zero pressure. (iii) Ice melting. Ice melting temperatures of up to 6.8 °C were measured in the absence of the vapour bubble, i.e. in the negative pressure region. (iv) Spontaneous retrograde and, for the first time, prograde vapour bubble nucleation. Prograde bubble nucleation occurred upon heating at temperatures above ice melting. The occurrence of prograde and retrograde vapour bubble nucleation in the same inclusions indicates a maximum of the bubble nucleation curve in the ϱ-T plane at around 40 °C. The new experimental data represent valuable benchmarks to evaluate and further improve theoretical models describing the p-V-T properties of metastable water in the low-temperature region.

  20. Production of sulphate-rich vapour during the Chicxulub impact and implications for ocean acidification

    Science.gov (United States)

    Ohno, Sohsuke; Kadono, Toshihiko; Kurosawa, Kosuke; Hamura, Taiga; Sakaiya, Tatsuhiro; Shigemori, Keisuke; Hironaka, Yoichiro; Sano, Takayoshi; Watari, Takeshi; Otani, Kazuto; Matsui, Takafumi; Sugita, Seiji

    2014-04-01

    The mass extinction event at the Cretaceous/Palaeogene boundary 65.5 Myr ago has been widely attributed to the Chicxulub impact, but the mechanisms of extinction remain debated. In the oceans, near-surface planktonic foraminifera suffered severe declines, in contrast to the relatively high survival rates of bottom-dwelling benthic foraminifera. The vapour produced by an impact into Chicxulub's target rocks, which include sulphate-rich anhydrite, could have led to global acid rain, which can explain the pattern of oceanic extinctions. However, it has been suggested that most of the sulphur in the target rocks would have been released as sulphur dioxide and would have stayed in the stratosphere for a long time. Here we show, from impact experiments into anhydrite at velocities exceeding 10 km s-1, that sulphur trioxide dominates over sulphur dioxide in the resulting vapour cloud. Our experiments suggest that the Chicxulub impact released a huge quantity of sulphur trioxide into the atmosphere, where it would have rapidly combined with water vapour to form sulphuric acid aerosol particles. We also find, using a theoretical model of aerosol coagulation following the Chicxulub impact, that larger silicate particles ejected during the impact efficiently scavenge sulphuric acid aerosol particles and deliver the sulphuric acid to the surface within a few days. The rapid surface deposition of sulphuric acid would cause severe ocean acidification and account for preferential extinction of planktonic over benthic foraminifera.

  1. Stomatal acclimation to vapour pressure deficit doubles transpiration of small tree seedlings with warming

    DEFF Research Database (Denmark)

    Marchin, Renée M.; Broadhead, Alice A.; Bostic, Laura E.

    2016-01-01

    Future climate change is expected to increase temperature (T) and atmospheric vapour pressure deficit (VPD) in many regions, but the effect of persistent warming on plant stomatal behaviour is highly uncertain. We investigated the effect of experimental warming of 1.9-5.1 °C and increased VPD of ...... with increasing VPD and may necessitate revision of current models based on this assumption....

  2. Acid-base balance in lake water

    Energy Technology Data Exchange (ETDEWEB)

    Brosset, C.

    1980-02-01

    As expected, the acid-base content of lake water is composed of strong base or acid, weak acids (mainly fulvic acid) and carbonic acid. All of these may be determined by using a simple titration method. The concentration of undissociated carbonic acid sometimes appears not to be in equilibrium with the CO/sub 2/-concentration in air. Observed supersaturation seems to be connected to the concentration of fulvic acid.

  3. Virucidal efficacy of hydrogen peroxide vapour disinfection.

    Science.gov (United States)

    Tuladhar, E; Terpstra, P; Koopmans, M; Duizer, E

    2012-02-01

    Viral contamination of surfaces is thought to be important in transmission. Chemical disinfection can be an effective means of intervention, but little is known about the virucidal efficacy of hydrogen peroxide vapour (HPV) against enteric and respiratory viruses. To measure the virucidal efficacy of HPV against respiratory and enteric viruses on materials representing those found in institutions and homes. Poliovirus, human norovirus genogroup II.4 (GII.4), murine norovirus 1, rotavirus, adenovirus and influenza A (H1N1) virus dried on to stainless steel, framing panel and gauze carriers were exposed to HPV 127 ppm for 1h at room temperature in an isolator. Poliovirus was also exposed to HPV at different locations in a room. The virucidal effect was measured by comparing recoverable viral titres against unexposed controls. Polymerase chain reaction was used to evaluate the effect of HPV on viral genome reduction. HPV disinfection resulted in complete inactivation of all viruses tested, characterized by >4 log(10) reduction in infectious particles for poliovirus, rotavirus, adenovirus and murine norovirus on stainless steel and framing panel carriers, and >2 log(10) reduction for influenza A virus on stainless steel and framing panel carriers, and for all viruses on gauze carriers. Complete inactivation of poliovirus was demonstrated at several locations in the room. Reductions in viral genomes were minimal on framing panel and gauze carriers but significant on stainless steel carriers; human norovirus GII.4 genome was most resistant to HPV treatment. HPV could be an effective virucidal against enteric and respiratory viruses contaminating in-house environments. Copyright © 2011 The Healthcare Infection Society. Published by Elsevier Ltd. All rights reserved.

  4. 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;...

  5. Fluidized-bed water vapour gasification at Guessing, Austria. Results of two years of trial operation; Wirbelschicht-Wasserdampf-Vergasung in der Anlage Guessing (A). Betriebserfahrungen aus zwei Jahren Demonstrationsbetrieb

    Energy Technology Data Exchange (ETDEWEB)

    Hofbauer, H.; Rauch, R.

    2003-07-01

    Sustainable power supply has become reality in the Austrian town of Guessing, which has one of Austria's biggest district heating networks as well as a RME plant. In 2000, a biomass-fuelled power plant for electric power generation was constructed. The plant works by fluidized-bed water vapourgasification and was commissioned in September 2001. The gas engine was installed in 2002. By the end of June 2003, 3,600 hours of operation had been reached. The gasifier worked according to expectations and the gas composition, the tar content of the product gas and the plant efficiency were in the projected range. This plant marked the step from a 100 kW(th) test plant at Vienna university to a 8 MW(th) industrial-scale plant. In addition, research and development by RENET Austria will be continued with the final goal of achieving an economically efficient biomass-fuelled power plant. (orig.) [German] Nachhaltige Energiewirtschaft ist fuer die Stadt Guessing seit Jahren Realitaet. Eines der groessten Fernwaermenetze und eine RME Anlage wurde bereits in Guessing errichtet. Zur Deckung des Energiebedarfes fehlte nur noch die Elektrizitaet. Daher wurde im Jahr 2000 ein Biomassekraftwerk auf Basis der Wirbelschichtdampfvergasung errichtet. Die Inbetriebnahme erfolgte im September 2001 und im April 2002 wurde der Gasmotor in Betrieb genommen. Bis Ende Juni 2003 wurden 3600 Betriebstunden des Vergasers inkl. Gasmotor erreicht. Die Ergebnisse dieser Demonstrationsanlage zeigen, dass der Vergaser wie geplant funktioniert, die Gaszusammensetzung, der Teergehalt des Produktgases und der Wirkungsgrad der Anlage innerhalb des geplanten Bereiches liegen. Mit Hilfe dieser Anlage wurde der notwendige Scale-up Schritt von der Technikumsanlage an der TU Wien (100 kW{sub th}) zu einer kommerziellen Anlage (8 MW{sub th}) erreicht. Zugleich wird die Forschung und Entwicklung von RENET Austria so weit fortgefuehrt, dass der Anlagenbauer ein wirtschaftliches Biomassekraftwerk auf den Markt

  6. Numerical study of the heat and material transport in the absorption of water vapour in aqueous LiBr solution; Numerische Untersuchung des Waerme- und Stofftransports bei der Absorption von Wasserdampf in waessriger LiBr-Loesung

    Energy Technology Data Exchange (ETDEWEB)

    Olbricht, Michael; Buchholz, Niklas; Fries, Simon; Addy, Joseph; Luke, Andrea [Kassel Univ. (Germany). Fachgebiet Technische Thermodynamik

    2016-07-01

    In absorption refrigerating machines with the working-material pair water/lithium bromide usually falling-film apparatuses are applied as absorbers, evaporators, and condensers. These are often performed as horizontal tube bundes. As critical, the process limiting component in the literature the absorper is called, because of which the their running, coupled heat and material transport processes are more detailedly theoretically studied. For this a model was developed, which maps starting from analytically describable physical connections the transport processes in the apparatus. The flow in the tube bundle is hereby divided in two sections, the flow in the liquid film on the tubes and the drop fall between the tubes. The basic equations are numerically solved under given boundary conditions, whereby for the description of the drop fall phase addititonally semi-empirical calculation approaches are used. The results are elucidated by means of concentration and temperature profiles in the film. A distinctly faster formation of the temperature boundary layer than the concentration boundary layer in the fim is shown, which makes the material transport to the limiting transport process in the absorber, which is already known from experimental studies.The physical plausibility of the model is by means of this fact confirmed by an analysis of the coupled transport processes by means of dimensionless characteristic numbers. Furthermore from the results an improvement of the heat and material transport at diminishing of the tube diameter can be derived. Just so by the results of the study an estimation method for the quality of the absorber by means of the subcooling is shown.

  7. Vapour-liquid interfacial properties of square-well chains from density functional theory and Monte Carlo simulation.

    Science.gov (United States)

    Martínez-Ruiz, Francisco José; Blas, Felipe J; Moreno-Ventas Bravo, A Ignacio; Míguez, José Manuel; MacDowell, Luis G

    2017-05-17

    The statistical associating fluid theory for attractive potentials of variable range (SAFT-VR) density functional theory (DFT) developed by [Gloor et al., J. Chem. Phys., 2004, 121, 12740-12759] is used to predict the interfacial behaviour of molecules modelled as fully-flexible square-well chains formed from tangentially-bonded monomers of diameter σ and potential range λ = 1.5σ. Four different model systems, comprising 4, 8, 12, and 16 monomers per molecule, are considered. In addition to that, we also compute a number of interfacial properties of molecular chains from direct simulation of the vapour-liquid interface. The simulations are performed in the canonical ensemble, and the vapour-liquid interfacial tension is evaluated using the wandering interface (WIM) method, a technique based on the thermodynamic definition of surface tension. Apart from surface tension, we also obtain density profiles, coexistence densities, vapour pressures, and critical temperature and density, paying particular attention to the effect of the chain length on these properties. According to our results, the main effect of increasing the chain length (at fixed temperature) is to sharpen the vapour-liquid interface and to increase the width of the biphasic coexistence region. As a result, the interfacial thickness decreases and the surface tension increases as the molecular chains get longer. The interfacial thickness and surface tension appear to exhibit an asymptotic limiting behaviour for long chains. A similar behaviour is also observed for the coexistence densities and critical properties. Agreement between theory and simulation results indicates that SAFT-VR DFT is only able to predict qualitatively the interfacial properties of the model. Our results are also compared with simulation data taken from the literature, including the vapour-liquid coexistence densities, vapour pressures, and surface tension.

  8. Flow based vs. demand based energy-water modelling

    Science.gov (United States)

    Rozos, Evangelos; Nikolopoulos, Dionysis; Efstratiadis, Andreas; Koukouvinos, Antonios; Makropoulos, Christos

    2015-04-01

    The water flow in hydro-power generation systems is often used downstream to cover other type of demands like irrigation and water supply. However, the typical case is that the energy demand (operation of hydro-power plant) and the water demand do not coincide. Furthermore, the water inflow into a reservoir is a stochastic process. Things become more complicated if renewable resources (wind-turbines or photovoltaic panels) are included into the system. For this reason, the assessment and optimization of the operation of hydro-power systems are challenging tasks that require computer modelling. This modelling should not only simulate the water budget of the reservoirs and the energy production/consumption (pumped-storage), but should also take into account the constraints imposed by the natural or artificial water network using a flow routing algorithm. HYDRONOMEAS, for example, uses an elegant mathematical approach (digraph) to calculate the flow in a water network based on: the demands (input timeseries), the water availability (simulated) and the capacity of the transmission components (properties of channels, rivers, pipes, etc.). The input timeseries of demand should be estimated by another model and linked to the corresponding network nodes. A model that could be used to estimate these timeseries is UWOT. UWOT is a bottom up urban water cycle model that simulates the generation, aggregation and routing of water demand signals. In this study, we explore the potentials of UWOT in simulating the operation of complex hydrosystems that include energy generation. The evident advantage of this approach is the use of a single model instead of one for estimation of demands and another for the system simulation. An application of UWOT in a large scale system is attempted in mainland Greece in an area extending over 130×170 km². The challenges, the peculiarities and the advantages of this approach are examined and critically discussed.

  9. Nanocellulose-Based Materials for Water Purification.

    Science.gov (United States)

    Voisin, Hugo; Bergström, Lennart; Liu, Peng; Mathew, Aji P

    2017-03-05

    Nanocellulose is a renewable material that combines a high surface area with high strength, chemical inertness, and versatile surface chemistry. In this review, we will briefly describe how nanocellulose is produced, and present-in particular, how nanocellulose and its surface modified versions affects the adsorption behavior of important water pollutants, e.g., heavy metal species, dyes, microbes, and organic molecules. The processing of nanocellulose-based membranes and filters for water purification will be described in detail, and the uptake capacity, selectivity, and removal efficiency will also be discussed. The processing and performance of nanocellulose-based membranes, which combine a high removal efficiency with anti-fouling properties, will be highlighted.

  10. Nanocellulose-Based Materials for Water Purification

    Directory of Open Access Journals (Sweden)

    Hugo Voisin

    2017-03-01

    Full Text Available Nanocellulose is a renewable material that combines a high surface area with high strength, chemical inertness, and versatile surface chemistry. In this review, we will briefly describe how nanocellulose is produced, and present—in particular, how nanocellulose and its surface modified versions affects the adsorption behavior of important water pollutants, e.g., heavy metal species, dyes, microbes, and organic molecules. The processing of nanocellulose-based membranes and filters for water purification will be described in detail, and the uptake capacity, selectivity, and removal efficiency will also be discussed. The processing and performance of nanocellulose-based membranes, which combine a high removal efficiency with anti-fouling properties, will be highlighted.

  11. Tunable Water-based Microwave Metasurface

    DEFF Research Database (Denmark)

    Kapitanova, Polina; Odit, Mikhail; Dobrykh, Dmitry

    2017-01-01

    A water-based dynamically tunable microwave metasurface is developed and experimentally investigated. A simple approach to tune the metasurface properties by changing the shape of water-based unit cells by gravitation force is proposed. The transmission spectra of the metasurface for linear...... and circular polarizations of the incident wave are numerically simulated and experimentally measured under the metasurface rotation around a horizontal axis. The measured changes of the transmission coefficient magnitude up to 8 dB at 1.25 GHz are reported while rotating the metasurface by the 90 degrees...... angle. The proposed approach can be used to design cheap metasurfaces for electromagnetic wave control in the microwave frequency range....

  12. Multi-scale organization of water vapor over low and mid-tropical Africa

    CSIR Research Space (South Africa)

    Botai, OJ

    2009-01-01

    Full Text Available In this study, data from the Southern Hemisphere ADditional OZonesondes (SHADOZ) are used to compute the spatially averaged water vapour (WVg) over low and mid-tropical Africa. Based on the SHADOZ stations, reanalysis data from the National Centres...

  13. Corrosion resistant coatings (Al@#2@#O@#3@#) produced by metal-organic chemical vapour deposition using ATSB

    NARCIS (Netherlands)

    Haanappel, V.A.C.; Haanappel, V.A.C.; van Corbach, H.D.; Fransen, T.; Gellings, P.J.

    1993-01-01

    The metal organic chemical vapour deposition (MOCVD) of amorphous alumina films on steel was performed in nitrogen at atmospheric pressure. This MOCVD process is based on the thermal decomposition of aluminium-tri-sec-butoxide (ATSB). The effect of the deposition temperature (within the range

  14. Low Temperature Growth of In2O3and InN Nanocrystals on Si(111 via Chemical Vapour Deposition Based on the Sublimation of NH4Cl in In

    Directory of Open Access Journals (Sweden)

    Tsokkou Demetra

    2009-01-01

    Full Text Available Abstract Indium oxide (In2O3 nanocrystals (NCs have been obtained via atmospheric pressure, chemical vapour deposition (APCVD on Si(111 via the direct oxidation of In with Ar:10% O2at 1000 °C but also at temperatures as low as 500 °C by the sublimation of ammonium chloride (NH4Cl which is incorporated into the In under a gas flow of nitrogen (N2. Similarly InN NCs have also been obtained using sublimation of NH4Cl in a gas flow of NH3. During oxidation of In under a flow of O2the transfer of In into the gas stream is inhibited by the formation of In2O3around the In powder which breaks up only at high temperatures, i.e.T > 900 °C, thereby releasing In into the gas stream which can then react with O2leading to a high yield formation of isolated 500 nm In2O3octahedrons but also chains of these nanostructures. No such NCs were obtained by direct oxidation forT G < 900 °C. The incorporation of NH4Cl in the In leads to the sublimation of NH4Cl into NH3and HCl at around 338 °C which in turn produces an efficient dispersion and transfer of the whole In into the gas stream of N2where it reacts with HCl forming primarily InCl. The latter adsorbs onto the Si(111 where it reacts with H2O and O2leading to the formation of In2O3nanopyramids on Si(111. The rest of the InCl is carried downstream, where it solidifies at lower temperatures, and rapidly breaks down into metallic In upon exposure to H2O in the air. Upon carrying out the reaction of In with NH4Cl at 600 °C under NH3as opposed to N2, we obtain InN nanoparticles on Si(111 with an average diameter of 300 nm.

  15. The ignitability of petrol vapours and potential for vapour phase explosion by use of TASER® law enforcement electronic control device.

    Science.gov (United States)

    Clarke, C; Andrews, S P

    2014-12-01

    An experimental study was made of the potential of the TASER-X26™ law enforcement electronic control device to ignite petrol vapours if used by an officer to incapacitate a person soaked in petrol, or within a flammable atmosphere containing petrol vapour. Bench scale tests have shown that a wooden mannequin with pig skin covering the chest was a suitable representation of a human target. Full scale tests using the mannequin have shown that the arc from a TASER-X26™ is capable of igniting petrol/air vapours on a petrol-soaked person. Further tests in a 1/5 scale and a full scale compartment have shown that if a TASER is used within a compartment, a petrol vapour explosion (deflagration) may be achieved. It is evident from this research that if used in a flammable vapour rich environment, the device could prove fatal not only to the target but the TASER® operator as well. Copyright © 2014 Forensic Science Society. Published by Elsevier Ireland Ltd. All rights reserved.

  16. A vapourized Δ(9)-tetrahydrocannabinol (Δ(9)-THC) delivery system part II: comparison of behavioural effects of pulmonary versus parenteral cannabinoid exposure in rodents.

    Science.gov (United States)

    Manwell, Laurie A; Ford, Brittany; Matthews, Brittany A; Heipel, Heather; Mallet, Paul E

    2014-01-01

    Studies of the rewarding and addictive properties of cannabinoids using rodents as animal models of human behaviour often fail to replicate findings from human studies. Animal studies typically employ parenteral routes of administration, whereas humans typically smoke cannabis, thus discrepancies may be related to different pharmacokinetics of parenteral and pulmonary routes of administration. Accordingly, a novel delivery system of vapourized Δ(9)-tetrahydrocannabinol (Δ(9)-THC) was developed and assessed for its pharmacokinetic, pharmacodynamic, and behavioural effects in rodents. A commercially available vapourizer was used to assess the effects of pulmonary (vapourized) administration of Δ(9)-THC and directly compared to parenteral (intraperitoneal, IP) administration of Δ(9)-THC. Sprague-Dawley rats were exposed to pure Δ(9)-THC vapour (1, 2, 5, 10, and 20mg/pad), using a Volcano® vapourizing device (Storz and Bickel, Germany) or IP-administered Δ(9)-THC (0.1, 0.3, 0.5, 1.0mg/kg), and drug effects on locomotor activity, food and water consumption, and cross-sensitization to morphine (5mg/kg) were measured. Vapourized Δ(9)-THC significantly increased feeding during the first hour following exposure, whereas IP-administered Δ(9)-THC failed to produce a reliable increase in feeding at all doses tested. Acute administration of 10mg of vapourized Δ(9)-THC induced a short-lasting stimulation in locomotor activity compared to control in the first of four hours of testing over 7days of repeated exposure; this chronic exposure to 10mg of vapourized Δ(9)-THC did not induce behavioural sensitization to morphine. These results suggest vapourized Δ(9)-THC administration produces behavioural effects qualitatively different from those induced by IP administration in rodents. Furthermore, vapourized Δ(9)-THC delivery in rodents may produce behavioural effects more comparable to those observed in humans. We conclude that some of the conflicting findings in animal

  17. Determination of the water content of foods: I. Indirect determination of the water content

    NARCIS (Netherlands)

    Reith, J.F.; Mossel, D.A.A.; Kamer, J.H. van de

    1948-01-01

    The indirect determination of the water content of foods is dealt witli on the basis of tlie following general considerations: A. The absolute vapour pressure of the water in the substance to be desiccated ; B. The absolute vapour pressure of the water in the surrounding air, C.

  18. Multifractal comparison of the extremes of rain rates and integrated vapour content

    Science.gov (United States)

    Gires, Auguste; Ni, Vincent; Bosser, Pierre; Tchiguirinskaia, Ioulia; Schertzer, Daniel

    2015-04-01

    Rainfall extremes are studied through the analyse of three related fields measured with the help of co-located devices installed in the roof of the Ecole des Ponts ParisTech building: (i) Integrated Water Vapour (IWV); it corresponds the amount of water vapour present in the vertical columns between a GPS ground receiver and corresponding satellites. It is estimated from the time shift between the expected duration the signal needs to reach the receiver (the two positions are known) and the actual one (ii) Rain rate measured by three optical disdrometers of two different types (Campbell Scientific PWS100 and OTT Parsivel2) (iii) Relative humidity measured by a dedicated sensor First the correlations between these quantities during significant events is analysed. It appears that although IWV tends to decrease (vapour condense to form drops that fall) and relative humidity to increase during a rainfall event, it turns out difficult to quantitatively characterize this link. It is possibly due to the fact that the scale gap between a punctual measure for the rain rate and an average over a few km height column for the IWV is too large. Finally the scaling features of these three fields are investigated with the help of the Universal Multifractal framework which has been extensively used to analyse and simulate geophysical fields extremely variable over wide ranges of scales. Only three parameters are used to characterize variability across scales: C1 the mean intermittency, alpha the multifractality index and H the non-conservative exponent. Retrieved features are compared and the notion of maximum observable singularity is used to quantify the extremes of the various fields. Authors acknowledge the financial support of the Interreg IV NEW RainGain project (www.raingain.eu) and the chair "hydrology for resilient cities" sponsored by Véolia, and the Climate-KIC Blue Green Dream project (bgd.org.uk/).

  19. Carbon dioxide, water vapour and energy fluxes over a semi ...

    Indian Academy of Sciences (India)

    42

    Key words: Eddy covariance; semi-evergreen forest; surface energy balance; Carbon dioxide. 25 flux; Indian .... following forest types and biomes (Champion and Seth 1968), namely Eastern wet alluvial. 86 grasslands ..... Turbulence characteristics of the site were analyzed (table 2 a-b)during whole period. 197 and four ...

  20. Diurnal and seasonal variations of surface water vapour density ...

    African Journals Online (AJOL)

    The stations were so selected to show a South-North transect and were representative of the regions to which they belong, namely: the Southern, the Midland and the Sahelian (Northern) regions. Results showed that the variations in each station and regions were influenced by the prevailing atmospheric conditions.

  1. Condensation of water vapour on moss-dominated biological soil ...

    Indian Academy of Sciences (India)

    in urban landscapes of Guangzhou, China; Atmos. Res. 86 21–29. Zangvil A and Druian P 1980 Measurements of dew at a desert site in southern Israel; Geograph. Res. Forum 2. 26–34. Zheng R A 1963 The dew characteristics in sandy land; Acta. Pedol. Sinica 11 84–91. MS received 26 May 2013; revised 26 July 2013; ...

  2. Extended UNIQUAC model for correlation and prediction of vapour-liquid-solid equilibria in aqueous salt systems containing non-electrolytes

    DEFF Research Database (Denmark)

    Iliuta, Maria C.; Thomsen, Kaj; Rasmussen, Peter

    2000-01-01

    to aqueous salt systems containing non-electrolytes in order to demonstrate its ability in representing solid-liquid-vapour (SLV) equilibrium and thermal property data for these strongly non-ideal systems. The model requires only pure component and binary temperature-dependent interaction parameters....... The calculations are based on an extensive database consisting of salt solubility data in pure and mixed solvents, VLE data for solvent mixtures and mixed solvent-electrolyte systems and thermal properties for mixed solvent solutions. Application of the model to the methanol-water system in the presence of several...... ions (Na+, K+, NH4+, Cl-, NO3-, SO42-, CO2- and HCO3-) shows that the Extended UNIQUAC model is able to give an accurate description of VLE and SLE in ternary add quaternary mixtures, using the name set of binary interaction parameters. The capability of the model to predict accurately the phase...

  3. Technical and Economic Working Domains of Industrial Heat Pumps: Part 2 - Ammonia-Water Hybrid Absorption-Compression Heat Pumps

    DEFF Research Database (Denmark)

    Jensen, Jonas Kjær; Ommen, Torben Schmidt; Markussen, Wiebke Brix

    2014-01-01

    of the zeotropic mixture, ammonia-water. To evaluate to which extent these advantages can be translated into feasible heat pump solutions, the working domain of the HACHP is investigated based on technical and economic constraints. The HACHP working domain is compared to that of the best possible vapour...

  4. Estimation of vapour pressure and partial pressure of subliming ...

    Indian Academy of Sciences (India)

    Administrator

    temperature curves are calculated at 80, 160 and 1000 mbar for salicylic acid and vanadyl bis-2,4- pentanedionate, a precursor used for chemical vapour deposition of vanadium oxides. Using a modification of the Langmuir equation, the partial pressure of these materials at different total pressures is also determined.

  5. Human volunteer study with PGME: Eye irritation during vapour exposure

    NARCIS (Netherlands)

    Emmen, H.H.; Muijser, H.; Arts, J.H.E.; Prinsen, M.K.

    2003-01-01

    The objective of this study was to establish the possible occurrence of eye irritation and subjective symptoms in human volunteers exposed to propylene glycol monomethyl ether (PGME) vapour at concentrations of 0, 100 and 150 ppm. Testing was conducted in 12 healthy male volunteers using a repeated

  6. Microscopic characterisation of suspended graphene grown by chemical vapour deposition

    NARCIS (Netherlands)

    Bignardi, L.; Dorp, W.F. van; Gottardi, S.; Ivashenko, O.; Dudin, P.; Barinov, A.; de Hosson, J.T.M.; Stöhr, M.; Rudolf, P.

    2013-01-01

    We present a multi-technique characterisation of graphene grown by chemical vapour deposition (CVD) and thereafter transferred to and suspended on a grid for transmission electron microscopy (TEM). The properties of the electronic band structure are investigated by angle-resolved photoelectron

  7. Making ET AAS Determination Less Dependent on Vapourization ...

    African Journals Online (AJOL)

    The general solution of the problem comes from the integration of running absorbance normalized with regard to vapour transportation velocity. ... those introduced together with excessive amounts of Mg and Pd. The methodology suggested reduced the error associated with change of atomization kinetics from 20 to 2 %.

  8. Morphology of carbon nanotubes prepared via chemical vapour ...

    Indian Academy of Sciences (India)

    2015-11-27

    Nov 27, 2015 ... Small angle neutron scattering (SANS) has been utilized to study the morphology of the multi-walled carbon nanotubes prepared by chemical vapour deposition of acetylene. The effects of various synthesis parameters like temperature, catalyst concentration and catalyst support on the size distribution of ...

  9. Morphology of carbon nanotubes prepared via chemical vapour ...

    Indian Academy of Sciences (India)

    Morphology of carbon nanotubes prepared via chemical vapour deposition technique using acetylene: A small angle neutron scattering investigation. D SEN1,∗, K DASGUPTA2, J BAHADUR1, S MAZUMDER1 and. D SATHIYAMOORTHY2. 1Solid State Physics; 2Powder Metallurgy Division, Bhabha Atomic Research ...

  10. Low pressure chemical vapour deposition at quasi-high flow

    NARCIS (Netherlands)

    Holleman, J.; Middelhoek, Jan

    1984-01-01

    A new chemical vapour deposition (CVD) technique is presented. It is especially advantageous for the deposition of compound materials. The technique improves the uniformity and reproducibility of the deposition. The economical use of gaseous reactants is improved by a factor varying between 5 and

  11. Influence of hydrogen on chemical vapour synthesis of different ...

    Indian Academy of Sciences (India)

    Administrator

    Abstract. The role of hydrogen in the catalytic chemical vapour deposition of carbon nanotubes using sputtered nickel thin film as a catalyst is explained in this work. The growth of different carbon nanostruc- tures with the variation in the precursor gas content was studied by keeping all other process parameters constant ...

  12. Making ET AAS Determination Less Dependent on Vapourization ...

    African Journals Online (AJOL)

    NICO

    bGerman Aerospace Center, PT-SW, 12489 Berlin, Germany. Received 4 December 2012, revised 5 May 2013, accepted 7 May 2013. ABSTRACT. The quantification of the analytes in ET AAS is normally attained by the measurement and integration of transient absorbance. High degree of atomization and constant vapour ...

  13. Aerosol assisted chemical vapour deposition of germanium thin ...

    Indian Academy of Sciences (India)

    Diethyl germanium bis-picolinate, [Et2Ge(O2CC5H4N)2], and trimethyl germanium quinaldate, [Me3Ge(O2CC9H6N)], have been used as precursors for deposition of thin films of germanium by aerosol assisted chemical vapour deposition (AACVD). The thermogravimetric analysis revealed complete volatilization of ...

  14. Vapour intrusion from the vadose zone—seven algorithms compared

    NARCIS (Netherlands)

    Provoost, J.; Bosman, A.; Reijnders, L.; Bronders, J.; Touchant, K.; Swartjes, F.

    2010-01-01

    Background, aim and scope: Vapours of volatile organic compounds (VOCs) emanating from contaminated soils may move through the unsaturated zone to the subsurface. VOC in the subsurface can be transported to the indoor air by convective air movement through openings in the foundation and basement.

  15. Erratum to: Measurement of copper vapour laser-induced ...

    Indian Academy of Sciences (India)

    Erratum to: Measurement of copper vapour laser-induced deformation of dielectric-coated mirror surface by. Michelson interferometer. A WAHID. ∗. , S KUNDU, J S B SINGH, A K SINGH, A KHATTAR,. S K MAURYA, J S DHUMAL and K DASGUPTA. Laser & Plasma Technology Division, Beam Technology Development ...

  16. Distillation with Vapour Compression. An Undergraduate Experimental Facility.

    Science.gov (United States)

    Pritchard, Colin

    1986-01-01

    Discusses the need to design distillation columns that are more energy efficient. Describes a "design and build" project completed by two college students aimed at demonstrating the principles of vapour compression distillation in a more energy efficient way. General design specifications are given, along with suggestions for teaching…

  17. Detection of explosive vapour using surface-enhanced Raman spectroscopy

    Science.gov (United States)

    Fang, X.; Ahmad, S. R.

    2009-11-01

    A commercially available nano-structured gold substrate was used for activating surface-enhanced Raman scattering (SERS). Raman spectra of the vapour of explosive material, triacetonetriperoxide (TATP), at trace concentrations produced from adsorbed molecules on such surfaces have been studied. Prominent Raman lines of the explosive molecular species were recorded at a sample temperature of ˜35°C, which is near to human body temperature. For this study, the concentration of the adsorbed TATP molecules on the nano-structured surface was varied by heating the sample to different temperatures and exposing the substrate to the sample vapour for different lengths of time. The intensities of the Raman lines have been found to increase with the increase in temperature and also with the increase in the duration of exposure for a fixed temperature. However, as expected, the Raman intensities have been found to saturate at higher temperatures and longer exposures. These saturation effects of the strengths of the Raman lines in the SERS of TATP vapour have been investigated in this paper. The results indicate that the optimisation for vapour deposition on the surface could be a crucial factor for any quantitative estimate of the concentration of the molecular species adsorbed on the nano-structured substrates.

  18. Measurement and modeling of high-pressure (vapour + liquid) equilibria of (CO{sub 2} + alcohol) binary systems

    Energy Technology Data Exchange (ETDEWEB)

    Gutierrez, Jorge E.; Bejarano, Arturo [Departamento de Ingenieria Quimica y Ambiental, Universidad Tecnica Federico Santa Maria, Avda. Espana 1680, Valparaiso (Chile); Fuente, Juan C. de la, E-mail: juan.delafuente@usm.c [Departamento de Ingenieria Quimica y Ambiental, Universidad Tecnica Federico Santa Maria, Avda. Espana 1680, Valparaiso (Chile); Centro Regional de Estudios en Alimentos Saludables, Blanco 1623, Valparaiso (Chile)

    2010-05-15

    An apparatus based on a static-analytic method assembled in this work was utilized to perform high pressure (vapour + liquid) equilibria measurements with uncertainties estimated at <5%. Complementary isothermal (vapour + liquid) equilibria results are reported for the (CO{sub 2} + 1-propanol), (CO{sub 2} + 2-methyl-1-propanol), (CO{sub 2} + 3-methyl-1-butanol), and (CO{sub 2} + 1-pentanol) binary systems at temperatures of (313, 323, and 333) K, and at pressure range of (2 to 12) MPa. For all the (CO{sub 2} + alcohol) systems, it was visually monitored to insure that there was no liquid immiscibility at the temperatures and pressures studied. The experimental results were correlated with the Peng-Robinson equation of state using the quadratic mixing rules of van der Waals with two adjustable parameters. The calculated (vapour + liquid) equilibria compositions were found to be in good agreement with the experimental values with deviations for the mol fractions <0.12 and <0.05 for the liquid and vapour phase, respectively.

  19. Burning water: The water footprint of biofuel-based transport

    NARCIS (Netherlands)

    Gerbens-Leenes, Winnie; Hoekstra, Arjen Ysbert

    2010-01-01

    The trend towards substitution of conventional transport fuels by biofuels requires additional water. The EU aims to replace 10 percent of total transport fuels by biofuels by 2020. This study calculates the water footprint (WF) of different transport modes using bio-ethanol, biodiesel or

  20. Antifungal Activity of Clove Essential Oil and its Volatile Vapour Against Dermatophytic Fungi

    OpenAIRE

    Chee, Hee Youn; Lee, Min Hee

    2007-01-01

    Antifungal activities of clove essential oil and its volatile vapour against dermatophytic fungi including Candida albicans, Epidermophyton floccosum. Microsporum audouinii, Trichophyton mentagrophytes, and Trichophyton rubrum were investigated. Both clove essential oil and its volatile vapour strongly inhibit spore germination and mycelial growth of the dermatophytic fungi tested. The volatile vapour of clove essential oil showed fungistatic activity whereas direct application of clove essen...

  1. Modelling global fresh surface water temperature

    NARCIS (Netherlands)

    Beek, L.P.H. van; Eikelboom, T.; Vliet, M.T.H. van; Bierkens, M.F.P.

    2011-01-01

    Temperature directly determines a range of water physical properties including vapour pressure, surface tension, density and viscosity, and the solubility of oxygen and other gases. Indirectly water temperature acts as a strong control on fresh water biogeochemistry, influencing sediment

  2. Water Usage at Forward Operating Bases

    Science.gov (United States)

    2010-06-01

    Minimum Estimates from non-DOD Sources • WHO recommends 50 liter per person per day – Gleick, P.H. (1996), “Basic Water Requirements for Human Activities...Gallons Low High 26 Gallons WATER REQUIREMENTS Per Soldier/Civilian/Contractor Source: K. Kinnevan, “Challenges and Water Technology Objectives for

  3. The dependence of water potential in shoots of Picea abies on air and soil water status

    Directory of Open Access Journals (Sweden)

    A. Sellin

    Full Text Available Where there is sufficient water storage in the soil the water potential (Ψx in shoots of Norway spruce [Picea abies (L. Karst.] is strongly governed by the vapour pressure deficit of the atmosphere, while the mean minimum values of Ψx usually do not drop below –1.5 MPa under meteorological conditions in Estonia. If the base water potential (Ψb is above –0.62 MPa, the principal factor causing water deficiency in shoots of P. abies may be either limited soil water reserves or atmospheric evaporative demand depending on the current level of the vapour pressure deficit. As the soil dries the stomatal control becomes more efficient in preventing water losses from the foliage, and the leaf water status, in turn, less sensitive to atmospheric demand. Under drought conditions, if Ψb falls below –0.62 MPa, the trees' water stress is mainly caused by low soil water availability. Further declines in the shoot water potential (below –1.5 MPa can be attributed primarily to further decreases in the soil water, i.e. to the static water stress.Key words. Hydrology (evapotranspiration · plant ecology · soil moisture.

  4. Water sorption and water permeability properties of edible film made from potato peel waste

    Directory of Open Access Journals (Sweden)

    Siti Hajar OTHMAN

    Full Text Available Abstract The water sorption and permeability properties of edible film produced from potato peel waste was investigated under different levels of relative humidity (23, 33, 43, 57, 75% RH and temperatures (5, 30, 50 °C. The water sorption behaviour and isotherms of the film were investigated by fitting water sorption data to the Peleg model and the Guggenheim, Anderson de Boer model (GAB model. The amount of moisture content, time required for the moisture content of the film to reach equilibrium, water sorption rate, and water sorption capacity increased when the relative humidity increased. The effect of temperature on moisture content, water sorption rate, water sorption capacity, and monolayer moisture content is complex and related to the water activity as well as the moisture content. Based on R2 and RMSE values, the Peleg and GAB models were respectively determined as excellent models to predict the water sorption properties of the films, thus supporting the reliability of water sorption behaviour prediction. The water vapour transmission rate and water vapour permeability increased with an increase in relative humidity and temperature. The sorption and permeability properties of the film are worth investigation since the final application of the film as food packaging is ultimately dependent on these behaviours.

  5. Rotatory power of sodium vapour oriented by laser radiation

    Energy Technology Data Exchange (ETDEWEB)

    Bicchi, P. (Siena Univ. (Italy). Ist. di Fisica); Moi, L.; Zambon, B. (Consiglio Nazionale delle Ricerche, Pisa (Italy). Lab. di Fisica Atomica e Moleculare)

    1979-01-11

    In this paper the rotatory power of sodium vapour is studied when laser light is used as pumping as well as analysis light. The possibility of having an analysis light whose frequency may be varied in a range larger than the interval between the D/sub 1/ and D/sub 2/ atomic lines allows us to get for the first time the complete shape of the rotation curve and to measure a rotation different from zero even for frequencies very far from the resonance ones. The complete orientation in the vapour caused by the laser pumping-light power permits to obtain very high rotation values. In a cell containing Na and 200 Torr of Ne, we measured, at 185/sup 0/C, 10/sup 0//cm of specific rotation. The dependence of the optical activity on the buffer gas pressure and on the frequency of the pumping light is also studied.

  6. Laser-Induced Chemical Vapour Deposition of Silicon Carbonitride

    OpenAIRE

    Besling, W.; van der Put, P.; Schoonman, J.

    1995-01-01

    Laser-induced Chemical Vapour Deposition of silicon carbonitride coatings and powders has been investigated using hexamethyldisilazane (HMDS) and ammonia as reactants. An industrial CW CO2-laser in parallel configuration has been used to heat up the reactant gases. HMDS dissociates in the laser beam and reactive radicals are formed which increase rapidly in molecular weight by an addition mechanism. Dense polymer-like silicon carbonitride thin films and nanosized powders are formed depending ...

  7. CHEMICAL VAPOUR DEPOSITION OF THE Al-O-N SYSTEM

    OpenAIRE

    Aspar, B.; Armas, B.; Combescure, C.; Thenegal, D.

    1991-01-01

    Using chemical vapour deposition, aluminium - oxygen-nitrogen coatings have been synthesized with aluminium trichloride, hydrogen, ammonia and nitrous oxide. The composition of the equilibrium phases is first determined by a thermodynamic calculation. The only AlON phase we investigate is ([MATH]) spinel aluminium oxynitride and it is considered as a stoichiometric phase with a composition of Al7O9N. The results indicate the existence fields of aluminium nitride and alumina and show the diffi...

  8. Chemical Vapour Deposition of Gas Sensitive Metal Oxides

    OpenAIRE

    Stella Vallejos; Francesco Di Maggio; Tahira Shujah; Chris Blackman

    2016-01-01

    This article presents a review of recent research efforts and developments for the fabrication of metal-oxide gas sensors using chemical vapour deposition (CVD), presenting its potential advantages as a materials synthesis technique for gas sensors along with a discussion of their sensing performance. Thin films typically have poorer gas sensing performance compared to traditional screen printed equivalents, attributed to reduced porosity, but the ability to integrate materials directly with ...

  9. Daytime Water Detection Based on Color Variation

    Science.gov (United States)

    Rankin, Arturo L.; Matthies, Larry H.

    2010-01-01

    Robust water detection is a critical perception requirement for unmanned ground vehicle (UGV) autonomous navigation. This is particularly true in wide open areas where water can collect in naturally occurring terrain depressions during periods of heavy precipitation and form large water bodies (such as ponds). At far range, reflections of the sky provide a strong cue for water. But at close range, the color coming out of a water body dominates sky reflections and the water cue from sky reflections is of marginal use. We model this behavior by using water body intensity data from multiple frames of RGB imagery to estimate the total reflection coefficient contribution from surface reflections and the combination of all other factors. Then we describe an algorithm that uses one of the color cameras in a forward- looking, UGV-mounted stereo-vision perception system to detect water bodies in wide open areas. This detector exploits the knowledge that the change in saturation-to-brightness ratio across a water body from the leading to trailing edge is uniform and distinct from other terrain types. In test sequences approaching a pond under clear, overcast, and cloudy sky conditions, the true positive and false negative water detection rates were (95.76%, 96.71%, 98.77%) and (0.45%, 0.60%, 0.62%), respectively. This software has been integrated on an experimental unmanned vehicle and field tested at Ft. Indiantown Gap, PA.

  10. Influence of metallic vapours on thermodynamic and transport properties of two-temperature air plasma

    Science.gov (United States)

    Zhong, Linlin; Wang, Xiaohua; Cressault, Yann; Teulet, Philippe; Rong, Mingzhe

    2016-09-01

    The metallic vapours (i.e., copper, iron, and silver in this paper) resulting from walls and/or electrode surfaces can significantly affect the characteristics of air plasma. Different from the previous works assuming local thermodynamic equilibrium, this paper investigates the influence of metallic vapours on two-temperature (2 T) air plasma. The 2 T compositions of air contaminated by Cu, Fe, and Ag are first determined based on Saha's and Guldberg-Waage's laws. The thermodynamic properties (including mass density, specific enthalpy, and specific heat) are then calculated according to their definitions. After determining the collision integrals for each pair of species in air-metal mixtures using the newly published methods and source data, the transport coefficients (including electrical conductivity, viscosity, and thermal conductivity) are calculated for air-Cu, air-Fe, and air-Ag plasmas with different non-equilibrium degree θ (Te/Th). The influences of metallic contamination as well as non-equilibrium degree are discussed. It is found that copper, iron, and silver exist mainly in the form of Cu2, FeO, and AgO at low temperatures. Generally, the metallic vapours increase mass density at most temperatures, reduce the specific enthalpy and specific heat in the whole temperature range, and affect the transport properties remarkably from 5000 K to 20 000 K. The effect arising from the type of metals is little except for silver at certain temperatures. Besides, the departure from thermal equilibrium results in the delay of dissociation and ionization reactions, leading to the shift of thermodynamic and transport properties towards a higher temperature.

  11. Solution and vapour deposited lead perovskite solar cells: Ecotoxicity from a life cycle assessment perspective

    DEFF Research Database (Denmark)

    Espinosa Martinez, Nieves; Serrano-Luján, Lucía; Urbina, Antonio

    2015-01-01

    We present a life cycle analysis (LCA) and an environmental impact analysis (EIA) of lead based perovskite solar cells prepared according to the two most successfully reported literature methods that comprise either vapour phase deposition or solution phase deposition. We have developed the inven......We present a life cycle analysis (LCA) and an environmental impact analysis (EIA) of lead based perovskite solar cells prepared according to the two most successfully reported literature methods that comprise either vapour phase deposition or solution phase deposition. We have developed...... in the analysis and further present a sensitivity analysis with the operational lifetime as a basis. We find that the major impact comes from the preparation of the perovskite absorber layer due to the electrical energy required in the manufacture and also make the striking observation that the impact of toxic...... lead(II)halides is very limited compared to methylammoniumhalides employed. This applies during the raw materials extraction, synthesis of the starting materials and manufacture of the perovskite solar cells and from these points of view the lead based perovskite solar cells do not pose extra concerns...

  12. Surface polish of PLA parts in FDM using dichloromethane vapour

    Directory of Open Access Journals (Sweden)

    Jin Yifan

    2017-01-01

    Full Text Available Fused deposition modelling has become one of the most diffused rapid prototyping techniques, which is widely used to fabricate prototypes. However, further application of this technology is severely limited by poor surface roughness. Thus it is necessary to adopt some operations to improve surface quality. Chemical finishing is typically employed to finish parts in fused deposition modelling (FDM. The purpose of this paper is to decrease the surface roughness for polylactic acid (PLA parts in FDM. The chemical reaction mechanism during the treating process is analysed. Then NaOH solution and dichloromethane vapour are used to treat FDM specimens respectively. A 3D laser microscope has been applied to assess the effects in terms of surface topography and roughness. The experimental results show that treatment using dichloromethane vapour performs much better than NaOH solution. Compared with the untreated group, surface roughness obtained through vapour treatment decreases by 88 per cent. This research has been conducted to provide a better method to treat PLA parts using chemical reagents.

  13. Assessment of water sources to plant growth in rice based cropping systems by stable water isotopes

    Science.gov (United States)

    Mahindawansha, Amani; Kraft, Philipp; Racela, Heathcliff; Breuer, Lutz

    2016-04-01

    Rice is one of the most water-consuming crops in the world. Understanding water source utilization of rice will help us to improve water use efficiency (WUE) in paddy management. The objectives of our study are to evaluate the isotopic compositions of surface ponded water, soil water, irrigation water, groundwater, rain water and plant water and based on stable water isotope signatures to evaluate the contributions of various water sources to plant growth (wet rice, aerobic rice and maize) together with investigating the contribution of water from different soil horizons for plant growth in different maturity periods during wet and dry seasons. Finally we will compare the water balances and crop yields in both crops during both seasons and calculate the water use efficiencies. This will help to identify the most efficient water management systems in rice based cropping ecosystems using stable water isotopes. Soil samples are collected from 9 different depths at up to 60 cm in vegetative, reproductive and matured periods of plant growth together with stem samples. Soil and plant samples are extracted by cryogenic vacuum extraction. Root samples are collected up to 60 cm depth from 10 cm intercepts leading calculation of root length density and dry weight. Groundwater, surface water, rain water and irrigation water are sampled weekly. All water samples are analyzed for hydrogen and oxygen isotope ratios (d18O and dD) using Los Gatos Research DLT100. Rainfall records, ground water level, surface water level fluctuations and the amount of water irrigated in each field will be measured during the sampling period. The direct inference approach which is based on comparing isotopic compositions (dD and d18O) between plant stem water and soil water will be used to determine water sources taken up by plant. Multiple-source mass balance assessment can provide the estimated range of potential contributions of water from each soil depth to root water uptake of a crop. These

  14. Soil moisture responses to vapour pressure deficit in polytunnel-grown tomato under soil moisture triggered irrigation control

    Science.gov (United States)

    Goodchild, Martin; Kühn, Karl; Jenkins, Dick

    2014-05-01

    The aim of this work has been to investigate soil-to-atmosphere water transport in potted tomato plants by measuring and processing high-resolution soil moisture data against the environmental driver of vapour pressure deficit (VPD). Whilst many researchers have successfully employed sap flow sensors to determine water uptake by roots and transport through the canopy, the installation of sap flow sensors is non-trivial. This work presents an alternative method that can be integrated with irrigation controllers and data loggers that employ soil moisture feedback which can allow water uptake to be evaluated against environmental drivers such as VPD between irrigation events. In order to investigate water uptake against VPD, soil moisture measurements were taken with a resolution of 2 decimal places - and soil moisture, air temperature and relative humidity measurements were logged every 2 minutes. Data processing of the soil moisture was performed in an Excel spread sheet where changes in water transport were derived from the rate of change of soil moisture using the Slope function over 5 soil moisture readings. Results are presented from a small scale experiment using a GP2-based irrigation controller and data logger. Soil moisture feedback is provided from a single SM300 soil moisture sensor in order to regulate the soil moisture level and to assess the water flow from potted tomato plants between irrigation events. Soil moisture levels were set to avoid drainage water losses. By determining the rate of change in soil moisture between irrigation events, over a 16 day period whilst the tomato plant was in flower, it has been possible to observe very good correlation between soil water uptake and VPD - illustrating the link between plant physiology and environmental conditions. Further data is presented for a second potted tomato plant where the soil moisture level is switched between the level that avoids drainage losses and a significantly lower level. This data

  15. Model studies of volatile diesel exhaust particle formation: organic vapours involved in nucleation and growth?

    Science.gov (United States)

    Pirjola, L.; Karl, M.; Rönkkö, T.; Arnold, F.

    2015-02-01

    High concentration of volatile nucleation mode particles (NUP) formed in the atmosphere during exhaust cools and dilutes have hazardous health effects and impair visibility in urban areas. Nucleation mechanisms in diesel exhaust are only poorly understood. We performed model studies using two sectional aerosol dynamics process models AEROFOR and MAFOR on the formation of particles in the exhaust of a diesel engine, equipped with an oxidative after-treatment system and running with low fuel sulphur content (FSC), under laboratory sampling conditions where the dilution system mimics real-world conditions. Different nucleation mechanisms were tested; based on the measured gaseous sulphuric acid (GSA) and non-volatile core and soot particle number concentrations of the raw exhaust, the model simulations showed that the best agreement between model predictions and measurements in terms of particle number size distribution was obtained by barrierless heteromolecular homogeneous nucleation between GSA and semi-volatile organic vapour (for example adipic acid) combined with the homogeneous nucleation of GSA alone. Major growth of the particles was predicted to occur by the same organic vapour at concentrations of (1-2) ×1012cm-3. The pre-existing core and soot mode concentrations had opposite trend on the NUP formation, and maximum NUP formation was predicted if a diesel particle filter (DPF) was used. On the other hand, NUP formation was ceased if the GSA concentration was less than 1010cm-3 which suggests, based on the measurements, the usage of biofuel to prevent volatile particles in diesel exhaust.

  16. Giant spin Hall effect in graphene grown by chemical vapour deposition.

    Science.gov (United States)

    Balakrishnan, Jayakumar; Koon, Gavin Kok Wai; Avsar, Ahmet; Ho, Yuda; Lee, Jong Hak; Jaiswal, Manu; Baeck, Seung-Jae; Ahn, Jong-Hyun; Ferreira, Aires; Cazalilla, Miguel A; Castro Neto, Antonio H; Özyilmaz, Barbaros

    2014-09-01

    Advances in large-area graphene synthesis via chemical vapour deposition on metals like copper were instrumental in the demonstration of graphene-based novel, wafer-scale electronic circuits and proof-of-concept applications such as flexible touch panels. Here, we show that graphene grown by chemical vapour deposition on copper is equally promising for spintronics applications. In contrast to natural graphene, our experiments demonstrate that chemically synthesized graphene has a strong spin-orbit coupling as high as 20 meV giving rise to a giant spin Hall effect. The exceptionally large spin Hall angle ~0.2 provides an important step towards graphene-based spintronics devices within existing complementary metal-oxide-semiconductor technology. Our microscopic model shows that unavoidable residual copper adatom clusters act as local spin-orbit scatterers and, in the resonant scattering limit, induce transverse spin currents with enhanced skew-scattering contribution. Our findings are confirmed independently by introducing metallic adatoms-copper, silver and gold on exfoliated graphene samples.

  17. Water-based Tourism - A Strategic Vision for Galway

    OpenAIRE

    Institute, Marine

    2002-01-01

    Water-based Tourism – A Strategic Vision for Galway is a report commissioned by a consortium of Agencies in collaboration with Ireland West Tourism. The terms of reference were to undertake a study which would: - evaluate the potential to develop the water-based tourism and leisure resource in Galway City and County; - identify the potential and provide a development strategy for at least six pilot water-based tourism and leisure initiatives in selected geographic locations throughout Galway;...

  18. The case for regime-based water quality standards

    Science.gov (United States)

    G.C. Poole; J.B. Dunham; D.M. Keenan; S.T. Sauter; D.A. McCullough; C. Mebane; J.C. Lockwood; D.A. Essig; M.P. Hicks; D.J. Sturdevant; E.J. Materna; S.A. Spalding; J. Risley; M. Deppman

    2004-01-01

    Conventional water quality standards have been successful in reducing the concentration of toxic substances in US waters. However, conventional standards are based on simple thresholds and are therefore poorly structured to address human-caused imbalances in dynamic, natural water quality parameters, such as nutrients, sediment, and temperature. A more applicable type...

  19. Factors affecting release of ethanol vapour in active modified atmosphere packaging systems for horticultural products

    Directory of Open Access Journals (Sweden)

    Weerawate Utto

    2014-04-01

    Full Text Available The active modified atmosphere packaging (active MAP system , which provides interactive postharvest control , using ethanol vapour controlled release, is one of the current interests in the development of active packaging for horticultural products. A number of published research work have discussed the relationship between the effectiveness of ethanol vapour and its concentration in the package headspace, including its effect on postharvest decay and physiological controls. This is of importance because a controlled release system should release and maintain ethanol vapour at effective concentrations during the desired storage period. A balance among the mass transfer processes of ethanol vapour in the package results in ethanol vapour accumulation in the package headspace. Key factors affecting these processes include ethanol loading, packaging material, packaged product and storage environment (temperature and relative h umidity. This article reviews their influences and discusses future work required to better understand their influences on ethanol vapour release and accumulations in active MAP.

  20. [Optimal allocation of irrigation water resources based on systematical strategy].

    Science.gov (United States)

    Cheng, Shuai; Zhang, Shu-qing

    2015-01-01

    With the development of the society and economy, as well as the rapid increase of population, more and more water is needed by human, which intensified the shortage of water resources. The scarcity of water resources and growing competition of water in different water use sectors reduce water availability for irrigation, so it is significant to plan and manage irrigation water resources scientifically and reasonably for improving water use efficiency (WUE) and ensuring food security. Many investigations indicate that WUE can be increased by optimization of water use. However, present studies focused primarily on a particular aspect or scale, which lack systematic analysis on the problem of irrigation water allocation. By summarizing previous related studies, especially those based on intelligent algorithms, this article proposed a multi-level, multi-scale framework for allocating irrigation water, and illustrated the basic theory of each component of the framework. Systematical strategy of optimal irrigation water allocation can not only control the total volume of irrigation water on the time scale, but also reduce water loss on the spatial scale. It could provide scientific basis and technical support for improving the irrigation water management level and ensuring the food security.

  1. Thermodynamic properties of critical clusters from measurements of vapour-liquid homogeneous nucleation rates

    Science.gov (United States)

    Ford, I. J.

    1996-11-01

    Two nucleation theorems are proved using small system thermodynamics. The first is well known and has been used before to determine the number of molecules in the critical nucleus controlling the nucleation of droplets from supersaturated vapours. The second appears to be new, and relates the temperature dependence of the nucleation rate to the excess internal energy of the critical cluster. An analysis of measured homogeneous nucleation rates can therefore provide the size, internal energy, free energy, and entropy of the critical cluster, which should provide important guidance for the construction of theoretical models of the process. This is illustrated using water, n-butanol and n-nonane nucleation data. While there is often a close correspondence between the droplet free energy and the form suggested by classical theory, the excess internal energy seems to show a linear dependence on molecular number, rather than the classical 2/3 power behaviour.

  2. (Vapour + liquid) equilibria of ternary systems with ionic liquids using headspace gas chromatography

    Energy Technology Data Exchange (ETDEWEB)

    Mokhtarani, Babak [Chemistry and Chemical Engineering Research Center of Iran, P.O. Box 14335-186, Tehran (Iran, Islamic Republic of); Gmehling, Juergen, E-mail: gmehling@tech.chem.uni-oldenburg.d [Carl von Ossietzky Universitaet Oldenburg, Technische Chemie, D-26111 Oldenburg (Germany)

    2010-08-15

    (Vapour + liquid) equilibrium (VLE) data for the ternary systems (hexane + benzene), (hexane + cyclohexane), (benzene + cyclohexane), and (ethanol + water) with an ionic liquid as entrainer for extractive distillation were measured by headspace gas chromatography. As ionic liquids, 1-hexyl-3-methyl-imidazolium bis (trifluoromethyl-sulfonyl) imide [HMIM][BTI], 1-octyl-3-methyl-imidazolium bis (trifluoromethyl-sulfonyl) imide [OMIM][BTI], 1-octyl-3-methyl-imidazolium trifluoro-methanesulfonate [OMIM][OTF], and 1-butyl-3-methyl-imidazolium trifluoro-methanesulfonate [BMIM][OTF] were used. The experimental data show that the ionic liquids investigated have a great influence on the separation factors of the systems (hexane + benzene), (hexane + cyclohexane), and (benzene + cyclohexane). The experimental data were compared with the predicted results using mod. UNIFAC (Do). The predicted results are in good agreement with the experimental data.

  3. Water based fluidic radio frequency metamaterials

    Science.gov (United States)

    Cai, Xiaobing; Zhao, Shaolin; Hu, Mingjun; Xiao, Junfeng; Zhang, Naibo; Yang, Jun

    2017-11-01

    Electromagnetic metamaterials offer great flexibility for wave manipulation and enable exceptional functionality design, ranging from negative refraction, anomalous reflection, super-resolution imaging, transformation optics to cloaking, etc. However, demonstration of metamaterials with unprecedented functionalities is still challenging and costly due to the structural complexity or special material properties. Here, we demonstrate for the first time the versatile fluidic radio frequency metamaterials with negative refraction using a water-embedded and metal-coated 3D architecture. Effective medium analysis confirms that metallic frames create an evanescent environment while simultaneously water cylinders produce negative permeability under Mie resonance. The water-metal coupled 3D architectures and the accessory devices for measurement are fabricated by 3D printing with post electroless deposition. Our study also reveals the great potential of fluidic metamaterials and versatility of the 3D printing process in rapid prototyping of customized metamaterials.

  4. Optimizing a Water Simulation based on Wavefront Parameter Optimization

    OpenAIRE

    Lundgren, Martin

    2017-01-01

    DICE, a Swedish game company, wanted a more realistic water simulation. Currently, most large scale water simulations used in games are based upon ocean simulation technology. These techniques falter when used in other scenarios, such as coastlines. In order to produce a more realistic simulation, a new one was created based upon the water simulation technique "Wavefront Parameter Interpolation". This technique involves a rather extensive preprocess that enables ocean simulations to have inte...

  5. Chemical vapour deposited diamonds for dosimetry of radiotherapeutical beams

    Energy Technology Data Exchange (ETDEWEB)

    Bucciolini, M.; Mazzocchi, S. [Firenze Univ., Firenze (Italy). Dipartimento di Fisiopatologia Clinica; INFN, Firenze (Italy); Borchi, E.; Bruzzi, M.; Pini, S.; Sciortino, S. [Firenze Univ., Firenze (Italy). Dipartimento di Energetica; INFN, Firenze (Italy); Cirrone, G.A.P.; Guttone, G.; Raffaele, L.; Sabini, M.G. [INFN, Catania (Italy). Laboratori Nazionali del Sud

    2002-07-01

    This paper deals with the application of synthetic diamond detectors to the clinical dosimetry of photon and electron beams. It has been developed in the frame of INFN CANDIDO project and MURST Cofin. Diamonds grown with CVD (Chemical Vapour Deposition) technique have been studied; some of them are commercial samples while others have been locally synthesised. Experiments have been formed using both on-line and off-line approaches. For the off-line measurements, TL (thermoluminescent) and TSC (thermally stimulated current) techniques have been used.

  6. Stub resonators Transmission - line - based water sensors

    NARCIS (Netherlands)

    Hoog-Antonyuk, N.A.

    2014-01-01

    The research presented in this thesis describes practical investigations in using stub resonator (as a transmission line) technology for different (on-) inline sensor applications in the field of water technology. In addition, a substantial part of the research has been devoted to provide an

  7. Europe's space telescope ISO finds water in distant places

    Science.gov (United States)

    1997-04-01

    Equally striking is ISO's discovery of water vapour in the outer planets, Saturn, Uranus and Neptune. As those chilly planets cannot release water from within, they probably have a supply of water coming from elsewhere in the Solar System. Since ISO went into orbit at the end of 1995, it has used its unique power of analysing infrared rays coming from the Universe to identify water vapour and water ice near dying stars and newborn stars. It has also measured the water vapour steaming from Comet Hale-Bopp. "Before ISO no instrument was capable of detecting water in so many places," comments ESA's director of science, Roger Bonnet. "To start revealing the cosmic history of the Earth's water is a big success for ESA and for the astronomers who use our unique infrared observatory. And ISO's discovery that water is commonplace in the Galaxy will encourage renewed speculation about life that may exist in the vicinity of other stars." Water amid the stars Primaeval hydrogen atoms make water by joining with oxygen atoms that are manufactured within stars, in nuclear reactions occurring towards the end of a star's life. Oxygen from defunct stars enriches the Galaxy, and abundant hydrogen is available to react with it. Although the existence of water in interstellar space is not surprising, the Earth's moist atmosphere makes life difficult for any astronomer who wishes to spot water vapour in the Universe with ground-based instruments. Observations from aircraft and balloons gave early hints of cosmic water, but thorough investigations had to wait for ISO's unhampered view from space. Three of the satellite's instruments, the Short Wavelength Spectrometer (SWS), the Long Wavelength Spectrometer (LWS) and the photometer ISOPHOT operating in spectroscopic mode, take part in the hunt for water. Last year, for example, users of both SWS and LWS reported water vapour in the vicinity of the aged star, W Hydrae, from which oxygen-rich winds blow into space. The bright infrared

  8. An Agent Based Model of Household Water Use

    Directory of Open Access Journals (Sweden)

    Clinton J. Andrews

    2013-07-01

    Full Text Available Households consume a significant fraction of total potable water production. Strategies to improve the efficiency of water use tend to emphasize technological interventions to reduce or shift water demand. Behavioral water use reduction strategies can also play an important role, but a flexible framework for exploring the “what-ifs” has not been available. This paper introduces such a framework, presenting an agent-based model of household water-consuming behavior. The model simulates hourly water-using activities of household members within a rich technological and behavioral context, calibrated with appropriate data. Illustrative experiments compare the resulting water usage of U.S. and Dutch households and their associated water-using technologies, different household types (singles, families with children, and retired couples, different water metering regimes, and educational campaigns. All else equal, Dutch and metered households use less water. Retired households use more water because they are more often at home. Water-saving educational campaigns are effective for the part of the population that is receptive. Important interactions among these factors, both technological and behavioral, highlight the value of this framework for integrated analysis of the human-technology-water system.

  9. Small drinking water systems under spatiotemporal water quality variability: a risk-based performance benchmarking framework.

    Science.gov (United States)

    Bereskie, Ty; Haider, Husnain; Rodriguez, Manuel J; Sadiq, Rehan

    2017-08-23

    Traditional approaches for benchmarking drinking water systems are binary, based solely on the compliance and/or non-compliance of one or more water quality performance indicators against defined regulatory guidelines/standards. The consequence of water quality failure is dependent on location within a water supply system as well as time of the year (i.e., season) with varying levels of water consumption. Conventional approaches used for water quality comparison purposes fail to incorporate spatiotemporal variability and degrees of compliance and/or non-compliance. This can lead to misleading or inaccurate performance assessment data used in the performance benchmarking process. In this research, a hierarchical risk-based water quality performance benchmarking framework is proposed to evaluate small drinking water systems (SDWSs) through cross-comparison amongst similar systems. The proposed framework (R WQI framework) is designed to quantify consequence associated with seasonal and location-specific water quality issues in a given drinking water supply system to facilitate more efficient decision-making for SDWSs striving for continuous performance improvement. Fuzzy rule-based modelling is used to address imprecision associated with measuring performance based on singular water quality guidelines/standards and the uncertainties present in SDWS operations and monitoring. This proposed R WQI framework has been demonstrated using data collected from 16 SDWSs in Newfoundland and Labrador and Quebec, Canada, and compared to the Canadian Council of Ministers of the Environment WQI, a traditional, guidelines/standard-based approach. The study found that the R WQI framework provides an in-depth state of water quality and benchmarks SDWSs more rationally based on the frequency of occurrence and consequence of failure events.

  10. Water System Architectures for Moon and Mars Bases

    Science.gov (United States)

    Jones, Harry W.; Hodgson, Edward W.; Kliss, Mark H.

    2015-01-01

    Water systems for human bases on the moon and Mars will recycle multiple sources of wastewater. Systems for both the moon and Mars will also store water to support and backup the recycling system. Most water system requirements, such as number of crew, quantity and quality of water supply, presence of gravity, and surface mission duration of 6 or 18 months, will be similar for the moon and Mars. If the water system fails, a crew on the moon can quickly receive spare parts and supplies or return to Earth, but a crew on Mars cannot. A recycling system on the moon can have a reasonable reliability goal, such as only one unrecoverable failure every five years, if there is enough stored water to allow time for attempted repairs and for the crew to return if repair fails. The water system that has been developed and successfully operated on the International Space Station (ISS) could be used on a moon base. To achieve the same high level of crew safety on Mars without an escape option, either the recycling system must have much higher reliability or enough water must be stored to allow the crew to survive the full duration of the Mars surface mission. A three loop water system architecture that separately recycles condensate, wash water, and urine and flush can improve reliability and reduce cost for a Mars base.

  11. A quasi-physical model for predicting the thermal insulation and moisture vapour resistance of clothing.

    Science.gov (United States)

    Qian, Xiaoming; Fan, Jintu

    2009-07-01

    Based on the improved understanding of the effects of wind and walking motion on the thermal insulation and moisture vapour resistance of clothing induced by air ventilation in the clothing system, a new model has been derived based on fundamental mechanisms of heat and mass transfer, which include conduction, diffusion, radiation and natural convection, wind penetration and air ventilation. The model predicts thermal insulation of clothing under body movement and windy conditions from the thermal insulation of clothing measured when the person is standing in the still air. The effects of clothing characteristics such as fabric air permeability, garment style, garment fitting and construction have been considered in the model through the key prediction parameters. With the new model, an improved prediction accuracy is achieved with a percentage of fit being as high as 0.96.

  12. Droplet spectrum at different vapour pressure deficits1

    Directory of Open Access Journals (Sweden)

    Christiam Felipe Silva Maciel

    Full Text Available ABSTRACT An efficient pesticides spraying depends a lot in psychrometric conditions, mainly if it is using fine droplets, once climatic conditions may cause droplets evaporation and consequent financial loss to the farmer. Thus, the aim of this work was to determine the droplet spectrum depending on the vapour pressure deficits. The work was carried out inside of a climate chamber to obtain the vapour pressure deficits (VPDair. The laser particle analyzer, model Spraytech, was used to determine the droplet spectrum, and the experiment was conducted in factorial scheme 5 x 20, consisted of five working pressures (100; 200; 300; 400 and 500 kPa and twenty VPDair (2.3; 3.2; 4.2; 5.6; 7.0; 7.4; 9.5; 11.7; 12.7; 15.8; 16.4; 16.9; 21.2; 22.1; 22.2; 28.1; 29.7; 36.9 39.4 e 51.6 hPa, in completely randomized design with five replications. There is influence of VPDair on droplet spectrum behavior. Increasing the VPDair reduces the percentage of sprayed volume comprised by droplets with diameter between 100 and 200 µm, between 200 and 300 µm, between 300 and 400 µm, between 400 and 500 µm and between 500 and 600 µm. Increasing VPDair increases the VMD, Dv90, SPAN and the percentage of sprayed volume comprised by droplets larger than 600 µm.

  13. THE IDENTIFICATION OF MONOETHANOLAMINE IN THE ATMOSPHERE USING TWO SENSORS ON THE BASE OF POTASSIUM FLUORIDE MICROPHASE

    Directory of Open Access Journals (Sweden)

    T. A. Kuchmenko

    2015-01-01

    Full Text Available The possibility of potassium fluoride microphase application as a modifier of a piezoelectric quartz crystal resonator, which is selective to vapour of based volatile organic compounds in the presence of water vapour, is studied. As an additional progressive impact on the system to increase the sensitivity of the microbalance, it is suggested to form the modifier layers of different thickness (mass. It is founded out that the increase in mass of potassium fluoride microphase changes the sensitivity of the sensor to selected analytes vapour differently. Unlike other substances investigated, amines are adsorbed by the surface of potassium fluoride coating without penetrating into the meso- and micropores. The polarity of analytes, the presence of hydrated functional groups and the residual solvent in the microphase affect the sensitivity of the microbalance in a greater degree. For detecting the vapour of alkylamines and monoethanolamine in gas environment it is preferable to use the sensor with a low-mass potassium fluoride film. In order to reduce the detection limit of the microbalance of mixed vapour of ketones and alkylacetates, a high-mass potassium fluoride film is recommended. Kinetic "visual prints" of a set of two sensors responses with different-mass potassium fluoride microphases have been built and divided into three groups. It is established that geometric form of "visual prints" of sensor responses does not depend on the concentration of substances in the mixture, but their area does. Kinetic "visual print" of sensor responces in monoethanol-amine vapour differs greatly from others. A new kinetic identification parameter A is proposed and calculated for all investigated analytes. A method of high-selective detection of monoethanolamine vapour has been proposed by a set of two sensors with different-mass coating in gas mixtures as well as in various samples containing it.

  14. Experimental demonstration of water based tunable metasurface

    DEFF Research Database (Denmark)

    Odit, Mikhail; Kapitanova, Polina; Andryieuski, Andrei

    2016-01-01

    A simple dynamically tunable metasurface (two-dimensional metamaterial) operating at microwave frequencies is developed and experimentally investigated. Conceptually, the simplicity of the approach is granted by reconfigurable properties of unit cells partially filled with distilled water....... The transmission spectra of the metasurface for linear and circular polarizations of the incident wave were experimentally measured under the metasurface rotation around a horizontal axis. The changes in the transmission coefficient magnitude up to 8 dB at 1.25 GHz are reported while rotating the metasurface...

  15. Vapour-phase crystallisation of silica from SiF4-bearing volcanic gases

    Directory of Open Access Journals (Sweden)

    M. H. G. Jacobs

    2005-06-01

    Full Text Available Thermodynamic modelling of magmatic gases shows that SiF4 may be an important F-bearing species at the high pressures typical of magma reservoirs. Upon decompression during degassing, SiF4 will react with water vapour to form HF and silica. Common magmatic gases of high-T fumaroles seem to contain too little SiF4 to be a significant source of silica, except if extremely large amounts of gas percolate through a small volume of rock, as is the case in lava domes. Only if fluorine contents of the gases exceed 1 mol% detectable amounts of silica may be formed, but such high fluorine contents have not yet been observed in natural gases. Alternatively, silica may be formed by heating of cool SiF4-rich gases circulating in cooling lava bodies. We suggest that these mechanisms may be responsible for the deposition of crystalline silica, most probably cristobalite, observed in vesicles in lavas from Lewotolo volcano (Eastern Sunda Arc, Indonesia. Silica occurs as vapour-crystallised patches in vesicles, and is sometimes associated with F-phlogopite, which further supports F-rich conditions during deposition. Because of the connection between F-rich conditions and high-K volcanism, we propose that late-stage gaseous transport and deposition of silica may be more widespread in K-rich volcanoes than elsewhere, and long-term exposure to ash from eruptions of such volcanoes could therefore carry an increased risk for respiratory diseases. The dependence of SiF4/HF on temperature reported here differs from the current calibration used for temperature measurements of fumarolic gases by remote sensing techniques, and we suggest an updated calibration.

  16. Evaluation method for regional water cycle health based on nature-society water cycle theory

    Science.gov (United States)

    Zhang, Shanghong; Fan, Weiwei; Yi, Yujun; Zhao, Yong; Liu, Jiahong

    2017-08-01

    Regional water cycles increasingly reflect the dual influences of natural and social processes, and are affected by global climate change and expanding human activities. Understanding how to maintain a healthy state of the water cycle has become an important proposition for sustainable development of human society. In this paper, natural-social attributes of the water cycle are synthesized and 19 evaluation indices are selected from four dimensions, i.e., water-based ecosystem integrity, water quality, water resource abundance and water resource use. A hierarchical water-cycle health evaluation system is established. An analytic hierarchy process is used to set the weight of the criteria layer and index layer, and the health threshold for each index is defined. Finally, a water-cycle health composite-index assessment model and fuzzy recognition model are constructed based on the comprehensive index method and fuzzy mathematics theory. The model is used to evaluate the state of health of the water cycle in Beijing during 2010-2014 and in the planning year (late 2014), considering the transfer of 1 billion m3 of water by the South-to-North Water Diversion Project (SNWDP). The results show health scores for Beijing of 2.87, 3.10, 3.38, 3.11 and 3.02 during 2010-2014. The results of fuzzy recognition show that the sub-healthy grade accounted for 54%, 49%, 61% and 49% of the total score, and all years had a sub-healthy state. Results of the criteria layer analysis show that water ecosystem function, water quality and water use were all at the sub-healthy level and that water abundance was at the lowest, or sick, level. With the water transfer from the SNWDP, the health score of the water cycle in Beijing reached 4.04. The healthy grade accounted for 60% of the total score, and the water cycle system was generally in a healthy state. Beijing's water cycle health level is expected to further improve with increasing water diversion from the SNWDP and industrial

  17. Methods for estimating the vapour pressure of organic chemicals; Application to five pesticides

    NARCIS (Netherlands)

    Leistra, M.

    2011-01-01

    When studying and modelling the volatilisation of pesticides from crops, their vapour pressure is an essential property. In the critical evaluation of vapour pressures stated by various sources, problems were encountered. Therefore, an inventory was made of readily-usable methods for estimating

  18. Vapour phase corrosion inhibitors from South African renewable resources and their evaluation

    CSIR Research Space (South Africa)

    Vuorinen, E

    2006-02-01

    Full Text Available A vapour-phase corrosion inhibitor (VCI) needs to be a volatile compound or a mixture of compounds. It reaches the surfaces that need to be protected from corrosion via the vapour phase and forms a relatively stable bond at the interface...

  19. Ethanol vapour sensing properties of screen printed WO3 thick films

    Indian Academy of Sciences (India)

    This paper presents ethanol vapour sensing properties of WO3 thick films. In this work, the WO3 thick films were prepared by standard screen-printing method. These films were characterized by X-ray diffraction (XRD) measurements and scanning electron microscopy (SEM). The ethanol vapour sensing properties of these ...

  20. New Method of Vapour Discrimination Using the Thickness Shear Mode (TSM Resonator

    Directory of Open Access Journals (Sweden)

    J. Siddiqi

    2003-06-01

    Full Text Available The Impedance analysis technique complimented with curve fitting software was used to monitor changes in film properties of Thickness Shear Mode (TSM resonator on vapour exposure. The approach demonstrates how sensor selectivity can be achieved through unique changes in film viscosity caused by organic vapour adsorption.

  1. Selenium Adsorption To Aluminum-Based Water Treatment Residuals

    Science.gov (United States)

    Aluminum-based water treatment residuals (WTR) can adsorb water-and soil-borne P, As(V), As(III), and perchlorate, and may be able to adsorb excess environmental selenium. WTR, clay minerals, and amorphous aluminum hydroxide were shaken for 24 hours in selenate or selenite solut...

  2. Water, sanitation and hygiene in community based care ...

    African Journals Online (AJOL)

    Inadequate access to water influences sanitation and hygiene, and this affects the work of CHW. Government needs to respond promptly to the water and sanitation needs of marginalized communities with limited resources. The findings of the study had implications for policy on WASH and community-based care in low ...

  3. Greening the global water system

    Science.gov (United States)

    Hoff, H.; Falkenmark, M.; Gerten, D.; Gordon, L.; Karlberg, L.; Rockström, J.

    2010-04-01

    SummaryRecent developments of global models and data sets enable a new, spatially explicit and process-based assessment of green and blue water in food production and trade. An initial intercomparison of a range of different (hydrological, vegetation, crop, water resources and economic) models, confirms that green water use in global crop production is about 4-5 times greater than consumptive blue water use. Hence, the full green-to-blue spectrum of agricultural water management options needs to be used when tackling the increasing water gap in food production. The different models calculate considerable potentials for complementing the conventional approach of adding irrigation, with measures to increase water productivity, such as rainwater harvesting, supplementary irrigation, vapour shift and soil and nutrient management. Several models highlight Africa, in particular sub-Saharan Africa, as a key region for improving water productivity in agriculture, by implementing these measures. Virtual water trade, mostly based on green water, helps to close the water gap in a number of countries. It is likely to become even more important in the future, when inequities in water availability are projected to grow, due to climate, population and other drivers of change. Further model developments and a rigorous green-blue water model intercomparison are proposed, to improve simulations at global and regional scale and to enable tradeoff analyses for the different adaptation options.

  4. Assessing water scarcity in agricultural production system based on the generalized water resources and water footprint framework.

    Science.gov (United States)

    Xinchun, Cao; Mengyang, Wu; Xiangping, Guo; Yalian, Zheng; Yan, Gong; Nan, Wu; Weiguang, Wang

    2017-12-31

    An indicator, agricultural water stress index (AWSI), was established based blue-green water resources and water footprint framework for regional water scarcity in agricultural production industry evaluation. AWSI is defined as the ratio of the total agricultural water footprint (AWF) to water resources availability (AWR) in a single year. Then, the temporal and spatial patterns of AWSI in China during 1999-2014 were analyzed based on the provincial AWR and AWF quantification. The results show that the annual AWR in China has been maintained at approximately 2540Gm3, of which blue water accounted for >70%. The national annual AWF was approximately 1040Gm3 during the study period and comprised 65.6% green, 12.7% blue and 21.7% grey WFs The space difference in both the AWF for per unit arable land (AWFI) and its composition was significant. National AWSI was calculated as 0.413 and showed an increasing trend in the observed period. This index increased from 0.320 (mid-water stress level) in 2000 to 0.490 (high water stress level) in the present due to the expansion of the agricultural production scale. The Northern provinces, autonomous regions and municipalities (PAMs) have been facing high water stress, particularly the Huang-Huai-Hai Plain, which was at a very high water stress level (AWSI>0.800). Humid South China faces increasingly severe water scarcity, and most of the PAMs in the region have converted from low water stress level (AWSI=0.100-0.200) to mid water stress level (AWSI=0.200-0.400). The AWSI is more appropriate for reflecting the regional water scarcity than the existing water stress index (WSI) or the blue water scarcity (BWS) indicator, particularly for the arid agricultural production regions due to the revealed environmental impacts of agricultural production. China should guarantee the sustainable use of agricultural water resources by reducing its crop water footprint. Copyright © 2017 Elsevier B.V. All rights reserved.

  5. Carrier phase altimetry using Zeppelin based GNSS-R observations and water gauge reference data

    Science.gov (United States)

    Semmling, Maximilian; Schön, Steffen; Beckheinrich, Jamila; Beyerle, Georg; Ge, Maorong; Wickert, Jens

    2014-05-01

    The increasing number of transmitters in global navigation satellite systems (GNSS), like GPS, Galileo, Glonass or Compass, provide observations with an increasing coverage for positioning but also for remote sensing. A space based GNSS remote sensing application is radio occultation, a limb sounding method. Globally distributed vertical profiles of temperature, water vapour and electron density are provided operationally for weather forecast and ionospheric monitoring. Another application is GNSS reflectometry (GNSS-R) that is currently developed especially for ocean remote sensing. The high reflection coefficient of water is crucial for GNSS-R. This study presents a method that uses GNSS phase observations for lake altimetry with the potential for ocean application. Phase observations are deduced from a GORS (GNSS Occultaction Reflectometry Scatterometry) receiver in Master-Slave-Configuration. The Master sampling dedicated for direct signal acquisition is connected to an up-looking antenna with right hand circular polarization (RHCP). Two Slave samplings dedicated for acquisition of the reflected signals are connected to down-looking antennas with right- and left-hand circular polarization (RHCP and LHCP). Based on in-phase and quad-phase (I, Q) sample components, an altimetric phase residual is retrieved. This residual can be related to the height of the reflecting surface. An altimetric challenge arises from the unknown ambiguity of phase residuals that introduces a height bias. The presented study uses ancillary data deduced from water gauges to mitigate the ambiguity bias. Reference tracks are formed by linear surface height interpolation between the water gauge stations. At crossover points of reflection tracks with reference tracks a phase ambiguity estimate is determined for bias mitigation. For this study airborne GNSS measurements were conducted aboard a Zeppelin NT (New Technology) airship with a geodetic receiver for navigation and a GORS receiver for

  6. Microwave plasma-enhanced chemical vapour deposition growth of carbon nanostructures

    Directory of Open Access Journals (Sweden)

    Shivan R. Singh

    2010-05-01

    Full Text Available The effect of various input parameters on the production of carbon nanostructures using a simple microwave plasma-enhanced chemical vapour deposition technique has been investigated. The technique utilises a conventional microwave oven as the microwave energy source. The developed apparatus is inexpensive and easy to install and is suitable for use as a carbon nanostructure source for potential laboratory-based research of the bulk properties of carbon nanostructures. A result of this investigation is the reproducibility of specific nanostructures with the variation of input parameters, such as carbon-containing precursor and support gas flow rate. It was shown that the yield and quality of the carbon products is directly controlled by input parameters. Transmission electron microscopy and scanning electron microscopy were used to analyse the carbon products; these were found to be amorphous, nanotubes and onion-like nanostructures.

  7. Effects of the ion-solid interaction in glow discharge vapour deposition polymerization of pyromellitic dianhydride

    Energy Technology Data Exchange (ETDEWEB)

    Maggioni, G. E-mail: maggioni@inl.infn.it; Carturan, S.; Rigato, V.; Pieri, U

    2000-05-02

    Low energy He ion bombardment of pyromellitic dianhydride monomer used in glow discharge vapour deposition polymerization (GDVDP) of polyimide coatings and its effects on the film deposition process have been studied. The sublimation of the monomer molecules and the simultaneous formation of a damaged, carbon-rich surface layer on the target are discussed from a theoretical point of view based on simulations of the ion-solid interaction. Optical emission and mass spectrometry have been used to analyse the species emitted from the target. In order to study the time evolution of the PMDA target damage, the deposition rate of monomer molecules has been monitored. FT-IR spectroscopy has been used to determine the molecular damaging of the target monomer and deposited films.

  8. Membrane-based processes for sustainable power generation using water.

    Science.gov (United States)

    Logan, Bruce E; Elimelech, Menachem

    2012-08-16

    Water has always been crucial to combustion and hydroelectric processes, but it could become the source of power in membrane-based systems that capture energy from natural and waste waters. Two processes are emerging as sustainable methods for capturing energy from sea water: pressure-retarded osmosis and reverse electrodialysis. These processes can also capture energy from waste heat by generating artificial salinity gradients using synthetic solutions, such as thermolytic salts. A further source of energy comes from organic matter in waste waters, which can be harnessed using microbial fuel-cell technology, allowing both wastewater treatment and power production.

  9. Membrane-based processes for sustainable power generation using water

    KAUST Repository

    Logan, Bruce E.

    2012-08-15

    Water has always been crucial to combustion and hydroelectric processes, but it could become the source of power in membrane-based systems that capture energy from natural and waste waters. Two processes are emerging as sustainable methods for capturing energy from sea water: pressure-retarded osmosis and reverse electrodialysis. These processes can also capture energy from waste heat by generating artificial salinity gradients using synthetic solutions, such as thermolytic salts. A further source of energy comes from organic matter in waste waters, which can be harnessed using microbial fuel-cell technology, allowing both wastewater treatment and power production. © 2012 Macmillan Publishers Limited. All rights reserved.

  10. Intercomparison of Lab-Based Soil Water Extraction Methods for Stable Water Isotope Analysis

    Science.gov (United States)

    Pratt, D.; Orlowski, N.; McDonnell, J.

    2016-12-01

    The effect of pore water extraction technique on resultant isotopic signature is poorly understood. Here we present results of an intercomparison of five common lab-based soil water extraction techniques: high pressure mechanical squeezing, centrifugation, direct vapor equilibration, microwave extraction, and cryogenic extraction. We applied five extraction methods to two physicochemically different standard soil types (silty sand and clayey loam) that were oven-dried and rewetted with water of known isotopic composition at three different gravimetric water contents (8, 20, and 30%). We tested the null hypothisis that all extraction techniques would provide the same isotopic result independent from soil type and water content. Our results showed that the extraction technique had a significant effect on the soil water isotopic composition. Each method exhibited deviations from spiked reference water, with soil type and water content showing a secondary effect. Cryogenic extraction showed the largest deviations from the reference water, whereas mechanical squeezing and centrifugation provided the closest match to the reference water for both soil types. We also compared results for each extraction technique that produced liquid water on both an OA-ICOS and IRMS; differences between them were negligible.

  11. radio frequency based radio frequency based water level monitor

    African Journals Online (AJOL)

    eobe

    Key words: radio frequency, PIC microcontroller, encoder, decoder, water pump, residential. 1. ... The sensors emit high frequency (20kHz to 200 kHz) acoustic waves that are reflected back to and detected by the emitting transducer [2-4]. In addition, optical interface ... is another method; in this method optical sensors are.

  12. Water-based Tourism and Leisure Product Audit 2006

    OpenAIRE

    Huskyes, E.; O?connor, K.

    2006-01-01

    In consultation with key agencies and stakeholders, the Marine Institute is drafting a Development Strategy for the marine/water-based tourism and leisure sector for the period 2007-2013. Preparation and research for this has involved the completion of a Water-based Tourism and Leisure Product Audit. The Institute worked in collaboration with Royal Haskoning, spatial planning consultants, and Kevin O’Connor, Donegal County Council, to complete the audit. The objective of the audit is to syste...

  13. Vapour pressure dependence and thermodynamics of cylindrical metal-organic framework mesoparticles: an ESEM study.

    Science.gov (United States)

    Sievers, Torsten K; Genre, Caroline; Bonnefond, Florent; Demars, Thomas; Ravaux, Johann; Meyer, Daniel; Podor, Renaud

    2013-10-14

    Self-assembly of neodymium nitrate and 2,5-dihydroxyl-1,4-benzoquinone (DHBQ) leads to the formation of a metal organic framework (MOF) of formula [Nd2(DHBQ)3(H2O)6]·18H2O. X-ray diffraction studies show that its crystalline structure is that of a two-dimensional coordination polymer packed in parallel sheets, with organised clusters of water molecules lying between the sheets and bridging them via a dense H-bond network. However, instead of forming faceted crystals, this MOF assembles into unusually shaped cylindrical particles of micrometre size. Scanning electron microscopy revealed that the particles are indeed mesoparticles from aggregated MOF crystalline nano-grains. The mesoparticles are stimuli-responsive and shrink in size upon exposure to reduced water vapour pressure. The shrinkage is isotropic and depends on temperature, which allows measuring the coexistence curve of water inside the particles and in the gas phase. Owing to an elaborated environmental scanning-electron microscopy (ESEM) study, it was possible to determine the association energy of water in the mesoparticles. We found a value of 16 ± 6.5 kJ mol(-1). Since the only water present in the particles is the lattice water in the nano-grains, this association energy is the lattice energy of water in the nano-sized MOF crystals. This value allowed us to draw a model for the building process of these originally shaped cylindrical mesoparticles. This is the first example of determination of a thermodynamic value by ESEM.

  14. Supramolecular water oxidation with rubda-based catalysts

    KAUST Repository

    Richmond, Craig J.

    2014-11-05

    Extremely slow and extremely fast new water oxidation catalysts based on the Rubda (bda = 2,2′-bipyri-dine-6,6′-dicarboxylate) systems are reported with turnover frequencies in the range of 1 and 900 cycless"1, respectively. Detailed analyses of the main factors involved in the water oxidation reaction have been carried out and are based on a combination of reactivity tests, electrochemical experiments, and DFT calculations. These analyses give a convergent interpretation that generates a solid understanding of the main factors involved in the water oxidation reaction, which in turn allows the design of catalysts with very low energy barriers in all the steps involved in the water oxidation catalytic cycle. We show that for this type of system p-stacking interactions are the key factors that influence reactivity and by adequately controlling them we can generate exceptionally fast water oxidation catalysts.

  15. Root water uptake model based on water potential gradient with water redistribution via roots: application to coniferous forest site

    Science.gov (United States)

    Votrubova, Jana; Vogel, Tomas; Dohnal, Michal; Dusek, Jaromir; Tesar, Miroslav

    2013-04-01

    A simple macroscopic vertically distributed plant root water uptake (RWU) model based on traditional water-potential-gradient formulation (Vogel et al., 2013), in which the uptake rates are directly proportional to the potential gradient and indirectly proportional to the local soil and root resistances to water flow, was tested. This RWU modeling approach was implemented in a one-dimensional dual-continuum model of soil water flow based on Richards' equation and used to simulate soil water distribution changes during a vegetation season at a forest site located in a temperate humid climate of central Europe. The main objectives were to test the ability of the presented RWU model to simulate the observed soil-plant-atmosphere interactions, and to examine the differences between empirical and more physically-based RWU modeling approaches (accommodated in the same soil water flow model). The tested RWU model was capable of simulating both the compensatory root water uptake, in situations when reduced uptake from dry layers was compensated for by increased uptake from wetter layers, and the root-mediated hydraulic redistribution of soil water, contributing to more natural soil moisture distribution throughout the root zone. Comparison of the model results with the sap flow observed reveals some limitations related to the quasi-steady-state assumption for the plant xylem and zero transpiration rates prescribed during nights and precipitation. This stated, the model seems to simulate adequately both the regular nightly hydraulic redistribution, due to reduced night transpiration, and the episodic daytime hydraulic redistribution during wet canopy events. The model results were compared to simulations produced using the semi-empirical RWU model of Feddes. Based on both an improved agreement between the observed and simulated soil water pressure responses to daily variations of transpiration, and a more realistic seasonal distribution of the transpiration rate reduction

  16. Scenario-based Water Resources Management Using the Water Value Concept

    Science.gov (United States)

    Hassanzadeh, Elmira; Elshorbagy, Amin; Wheater, Howard

    2013-04-01

    The Saskatchewan River is the key water resource for the 3 prairie provinces of Alberta, Saskatchewan and Manitoba in Western Canada, and thus it is necessary to pursue long-term regional and watershed-based planning for the river basin. The water resources system is complex because it includes multiple components, representing various demand sectors, including the environment, which impose conflicting objectives, and multiple jurisdictions. The biophysical complexity is exacerbated by the socioeconomic dimensions associated for example with impacts of land and water management, value systems including environmental flows, and policy and governance dimensions.. We focus on the South Saskatchewan River Basin (SSRB) in Alberta and Saskatchewan, which is already fully allocated in southern Alberta and is subject to increasing demand due to rapid economic development and a growing population. Multiple sectors and water uses include agricultural, municipal, industrial, mining, hydropower, and environmental flow requirements. The significant spatial variability in the level of development and future needs for water places different values on water across the basin. Water resources planning and decision making must take these complexities into consideration, yet also deal with a new dimension—climate change and its possible future impacts on water resources systems. There is a pressing need to deal with water in terms of its value, rather than a mere commodity subject to traditional quantitative optimization. In this research, a value-based water resources system (VWRS) model is proposed to couple the hydrological and the societal aspects of water resources in one integrated modeling tool for the SSRB. The objective of this work is to develop the VWRS model as a negotiation, planning, and management tool that allows for the assessment of the availability, as well as the allocation scenarios, of water resources for competing users under varying conditions. The proposed

  17. Thermal stability of γ-Fe2O3 nanoparticles and their employment for sensing of acetone vapours

    Science.gov (United States)

    Luby, Š.; Ivančo, J.; Jergel, M.; Švec, P., Jr.; Kotlár, M.; Kostiuk, D.; Halahovets, J.; Kollár, J.; Mosnáček, J.; Majková, E.

    2017-12-01

    Stability of γ-Fe2O3 nanoparticles-based films upon an isochronal annealing in air was investigated by x-ray diffraction, differential scanning calorimetry, and thermogravimetry. The γ-α transformation temperature increased owing to the nanoscaling of Fe2O3; the higher stability of the γ phase was explained on the ground of the surface free energy of nanoparticles (with the size of about 6.4 nm). Further, chemiresistors based on the Fe2O3 nanoparticle bilayer prepared by the Langmuir-Schaefer method were fabricated and examined in terms of their sensitivity to acetone vapours down to 500 ppb concentration in air.

  18. Hierarchically arranged helical fibre actuators driven by solvents and vapours

    Science.gov (United States)

    Chen, Peining; Xu, Yifan; He, Sisi; Sun, Xuemei; Pan, Shaowu; Deng, Jue; Chen, Daoyong; Peng, Huisheng

    2015-12-01

    Mechanical responsiveness in many plants is produced by helical organizations of cellulose microfibrils. However, simple mimicry of these naturally occurring helical structures does not produce artificial materials with the desired tunable actuations. Here, we show that actuating fibres that respond to solvent and vapour stimuli can be created through the hierarchical and helical assembly of aligned carbon nanotubes. Primary fibres consisting of helical assemblies of multiwalled carbon nanotubes are twisted together to form the helical actuating fibres. The nanoscale gaps between the nanotubes and micrometre-scale gaps among the primary fibres contribute to the rapid response and large actuation stroke of the actuating fibres. The compact coils allow the actuating fibre to rotate reversibly. We show that these fibres, which are lightweight, flexible and strong, are suitable for a variety of applications such as energy-harvesting generators, deformable sensing springs and smart textiles.

  19. Atmospheric pressure vapour phase decomposition: a proof of principle.

    Science.gov (United States)

    Cinosi, Amedeo; Andriollo, Nunzio; Tibaldi, Francesca; Monticelli, Damiano

    2012-11-15

    In the present work we demonstrated that the digestion of difficult matrices (high boiling petrochemical fractions and distillation bottoms) can be achieved by oxidation with nitric acid vapours at atmospheric pressure employing simple laboratory glassware. The application of this procedure as a digestion method prior to Total Reflection X-Ray Fluorescence (TXRF) is presented, although the employment of other detection techniques may be foreseen. The method ensured a fast, less than half an hour, treatment time and detection limits in the range 20-100 μg/kg for As, Bi, Co, Cr, Cu, Fe, Mn, Ni, Pb, Sr, Zn, whereas higher values were obtained for Ba, Ca, K, P, Rh, Ti and V (0.3-3 mg/kg). The potentialities and limitations of this procedure were discussed: the application to a broad range of matrices may be foreseen. Copyright © 2012 Elsevier B.V. All rights reserved.

  20. The Chemical Vapour Deposition of Tantalum - in long narrow channels

    DEFF Research Database (Denmark)

    Mugabi, James Atwoki

    concentrations in order to document the effects of these properties on the tantalum deposition rates. A kinetic model is developed upon the foundation of a Computational Fluid Dynamics (CFD) and Thermal model in order to broaden the understanding of the process and to identify the key control parameters...... mechanism of reaction, TaCl3 is found to have a lot of relevance such that it is the main precursor to the surface reaction and that the overall deposition rates follow its abundance. An experiment with a real plate heat exchanger is also done and the corresponding model implemented with satisfactory...... use as a construction material for process equipment, with the cheaper alternative being the construction of equipment from steel and then protecting it with a thin but efficacious layer of tantalum. Chemical Vapour Deposition (CVD) is chosen as the most effective process to apply thin corrosion...

  1. Thermoluminescence characterisation of chemical vapour deposited diamond films

    CERN Document Server

    Mazzocchi, S; Bucciolini, M; Cuttone, G; Pini, S; Sabini, M G; Sciortino, S

    2002-01-01

    The thermoluminescence (TL) characteristics of a set of six chemical vapour deposited diamond films have been studied with regard to their use as off-line dosimeters in radiotherapy. The structural characterisation has been performed by means of Raman spectroscopy. Their TL responses have been tested with radiotherapy beams ( sup 6 sup 0 Co photons, photons and electrons from a linear accelerator (Linac), 26 MeV protons from a TANDEM accelerator) in the dose range 0.1-7 Gy. The dosimetric characterisation has yielded a very good reproducibility, a very low dependence of the TL response on the type of particle and independence of the radiation energy. The TL signal is not influenced by the dose rate and exhibits a very low thermal fading. Moreover, the sensitivity of the diamond samples compares favourably with that of standard TLD100 dosimeters.

  2. Chemical Vapour Deposition of Gas Sensitive Metal Oxides

    Directory of Open Access Journals (Sweden)

    Stella Vallejos

    2016-03-01

    Full Text Available This article presents a review of recent research efforts and developments for the fabrication of metal-oxide gas sensors using chemical vapour deposition (CVD, presenting its potential advantages as a materials synthesis technique for gas sensors along with a discussion of their sensing performance. Thin films typically have poorer gas sensing performance compared to traditional screen printed equivalents, attributed to reduced porosity, but the ability to integrate materials directly with the sensor platform provides important process benefits compared to competing synthetic techniques. We conclude that these advantages are likely to drive increased interest in the use of CVD for gas sensor materials over the next decade, whilst the ability to manipulate deposition conditions to alter microstructure can help mitigate the potentially reduced performance in thin films, hence the current prospects for use of CVD in this field look excellent.

  3. Evaluating the virucidal efficacy of hydrogen peroxide vapour.

    Science.gov (United States)

    Goyal, S M; Chander, Y; Yezli, S; Otter, J A

    2014-04-01

    Surface contamination has been implicated in the transmission of certain viruses, and surface disinfection can be an effective measure to interrupt the spread of these agents. To evaluate the in-vitro efficacy of hydrogen peroxide vapour (HPV), a vapour-phase disinfection method, for the inactivation of a number of structurally distinct viruses of importance in the healthcare, veterinary and public sectors. The viruses studied were: feline calicivirus (FCV, a norovirus surrogate); human adenovirus type 1; transmissible gastroenteritis coronavirus of pigs (TGEV, a severe acute respiratory syndrome coronavirus [SARS-CoV] surrogate); avian influenza virus (AIV); and swine influenza virus (SwIV). The viruses were dried on stainless steel discs in 20- or 40-μL aliquots and exposed to HPV produced by a Clarus L generator (Bioquell, Horsham, PA, USA) in a 0.2-m(3) environmental chamber. Three vaporized volumes of hydrogen peroxide were tested in triplicate for each virus: 25, 27 and 33 mL. No viable viruses were identified after HPV exposure at any of the vaporized volumes tested. HPV was virucidal (>4-log reduction) against FCV, adenovirus, TGEV and AIV at the lowest vaporized volume tested (25 mL). For SwIV, due to low virus titre on the control discs, >3.8-log reduction was shown for the 25-mL vaporized volume and >4-log reduction was shown for the 27-mL and 33-mL vaporized volumes. HPV was virucidal for structurally distinct viruses dried on surfaces, suggesting that HPV can be considered for the disinfection of virus-contaminated surfaces. Copyright © 2014 The Healthcare Infection Society. Published by Elsevier Ltd. All rights reserved.

  4. A global analysis on water-based fire extinguishing agent

    Science.gov (United States)

    WANG, Shuai

    2017-04-01

    Due to the superiority of the attribute of water, water-based fire extinguishing agent is considered as one of most effectively fire extinguishing agents. NFPA has developed two standards regarding to water-based fire extinguishing agents. ISO technical committee working group is also preparing for developing a standard about the subject fire extinguishing agent. China also has its own national GB standard about water-based standard. This paper aims at to elaborate standard requirements and methods in different technical documents and standards currently available around the world with a view to summarize the main concern in different standards, and trying to find out valuable information for readers in future research and development.

  5. Water sorption and solubility of polyamide denture base materials.

    Science.gov (United States)

    Nguyen, Long G; Kopperud, Hilde M; Øilo, Marit

    2017-01-01

    Purpose: Some patients experience adverse reactions to poly(methyl methacrylate)-based (PMMA) dentures. Polyamide (PA) as an alternative to PMMA has, however, not been well documented with regard to water sorption and water solubility. The aim of this in vitro study was to measure water sorption and water solubility of two PA materials compared with PMMA, and to evaluate the major components released from the PA materials and the effect on hardness of the materials. Methods: Ten discs (40.0 mm diameter, 2.0 mm thick) of each material (PA: Valplast and Breflex; PMMA: SR Ivocap HIP) were prepared according to manufacturers' recommendations. The specimens were tested for water sorption and water solubility, according to a modification of ISO 20795-1:2008. Released substances were analysed by gas chromatography/mass spectrometry (GC/MS). Results: There were statistically significant differences among the materials regarding water sorption, water solubility and time to water saturation. Breflex had the highest water sorption (30.4 μg/mm(3)), followed by PMMA-material (25.8 μg/mm(3)) and Valplast (13.6 μg/mm(3)). Both PA materials had statistically significant lower water solubility than the PMMA. Both PA had a net increase in weight. Analysis by GC/MS identified release of the compound 12-aminododecanolactam from the material Valplast. No release was found from the Breflex material. Conclusions: The PA denture materials show differences in water sorption and solubility, but within the limits of the standard requirements. The PA showed a net increase in weight after long-term water sorption. The clinical implications of the findings are not elucidated.

  6. National Irrigation Water Quality Program data-synthesis data base

    Science.gov (United States)

    Seiler, Ralph L.; Skorupa, Joseph P.

    2001-01-01

    Under the National Irrigation Water Quality Program (NIWQP) of the U.S. Department of the Interior, researchers investigated contamination caused by irrigation drainage in 26 areas in the Western United States from 1986 to 1993. From 1992 to 1995, a comprehensive relational data base was built to organize data collected during the 26-area investigations. The data base provided the basis for analysis and synthesis of these data to identify common features of contaminated areas and hence dominant biologic, geologic, climatic, chemical, and physiographic factors that have resulted in contamination of water and biota in irrigated areas in the Western United States. Included in the data base are geologic, hydrologic, climatological, chemical, and cultural data that describe the 26 study areas in 14 Western States. The data base contains information on 1,264 sites from which water and bottom sediment were collected. It also contains chemical data from 6,903 analyses of surface water, 914 analyses of ground water, 707 analyses of inorganic constituents in bottom sediments, 223 analyses of organochlorine pesticides in bottom sediments, 8,217 analyses of inorganic constituents in biota, and 1,088 analyses for organic constituents in biota. The data base is available to the public and can be obtained at the NIWQP homepage http://www.usbr.gov/niwqp as dBase III tables for personal-computer systems or as American Standard Code for Information Exchange structured query language (SQL) command and data files for SQL data bases.

  7. Drinking Water Contamination Due To Lead-based Solder

    Science.gov (United States)

    Garcia, N.; Bartelt, E.; Cuff, K. E.

    2004-12-01

    The presence of lead in drinking water creates many health hazards. Exposure to lead-contaminated water can affect the brain, the central nervous system, blood cells, and kidneys, causing such problems as mental retardation, kidney disease, heart disease, stroke, and death. One way in which lead can contaminate our water supply is through the use of lead solder to join pipes. Lead solder was widely used in the past because of its ease of application as well as its low cost. Lead contamination in residential areas has previously been found to be a particularly serious problem in first-draw samples, of water that has sat stagnant in pipes overnight. To investigate the time-dependence of drinking water lead contamination, we analyzed samples taken hourly of water exposed to lead solder. While our preliminary data was insufficient to show more than a rough correlation between time of exposure and lead concentration over short periods (1-3 hours), we were able to confirm that overnight exposure of water to lead-based solder results in the presence high levels of lead. We also investigated other, external factors that previous research has indicated contribute to increased concentrations of lead. Our analysis of samples of lead-exposed water at various pH and temperatures suggests that these factors can be equally significant in terms of their contribution to elevated lead concentration levels. In particular, water that is slightly corrosive appears to severely impact the solubility of lead. As this type of water is common in much of the Northeast United States, the presence of lead-based solder in residential areas there is especially problematic. Although lead-based solder has been banned since the 1980s, it remains a serious concern, and a practical solution still requires further research.

  8. Model studies of volatile diesel exhaust particle formation: are organic vapours involved in nucleation and growth?

    Science.gov (United States)

    Pirjola, L.; Karl, M.; Rönkkö, T.; Arnold, F.

    2015-09-01

    A high concentration of volatile nucleation mode particles (NUP) formed in the atmosphere when the exhaust cools and dilutes has hazardous health effects and it impairs the visibility in urban areas. Nucleation mechanisms in diesel exhaust are only poorly understood. We performed model studies using two sectional aerosol dynamics process models AEROFOR and MAFOR on the formation of particles in the exhaust of a diesel engine, equipped with an oxidative after-treatment system and running with low fuel sulfur content (FSC) fuel, under laboratory sampling conditions where the dilution system mimics real-world conditions. Different nucleation mechanisms were tested. Based on the measured gaseous sulfuric acid (GSA) and non-volatile core and soot particle number concentrations of the raw exhaust, the model simulations showed that the best agreement between model predictions and measurements in terms of particle number size distribution was obtained by barrier-free heteromolecular homogeneous nucleation between the GSA and a semi-volatile organic vapour combined with the homogeneous nucleation of GSA alone. Major growth of the particles was predicted to occur due to the similar organic vapour at concentrations of (1-2) × 1012 cm-3. The pre-existing core and soot mode concentrations had an opposite trend on the NUP formation, and the maximum NUP formation was predicted if a diesel particle filter (DPF) was used. On the other hand, the model predicted that the NUP formation ceased if the GSA concentration in the raw exhaust was less than 1010 cm-3, which was the case when biofuel was used.

  9. Pollution source localization in an urban water supply network based on dynamic water demand.

    Science.gov (United States)

    Yan, Xuesong; Zhu, Zhixin; Li, Tian

    2017-10-27

    Urban water supply networks are susceptible to intentional, accidental chemical, and biological pollution, which pose a threat to the health of consumers. In recent years, drinking-water pollution incidents have occurred frequently, seriously endangering social stability and security. The real-time monitoring for water quality can be effectively implemented by placing sensors in the water supply network. However, locating the source of pollution through the data detection obtained by water quality sensors is a challenging problem. The difficulty lies in the limited number of sensors, large number of water supply network nodes, and dynamic user demand for water, which leads the pollution source localization problem to an uncertainty, large-scale, and dynamic optimization problem. In this paper, we mainly study the dynamics of the pollution source localization problem. Previous studies of pollution source localization assume that hydraulic inputs (e.g., water demand of consumers) are known. However, because of the inherent variability of urban water demand, the problem is essentially a fluctuating dynamic problem of consumer's water demand. In this paper, the water demand is considered to be stochastic in nature and can be described using Gaussian model or autoregressive model. On this basis, an optimization algorithm is proposed based on these two dynamic water demand change models to locate the pollution source. The objective of the proposed algorithm is to find the locations and concentrations of pollution sources that meet the minimum between the analogue and detection values of the sensor. Simulation experiments were conducted using two different sizes of urban water supply network data, and the experimental results were compared with those of the standard genetic algorithm.

  10. Comparison of two tracer gas dilution methods for the determination of clothing ventilation and of vapour resistance.

    Science.gov (United States)

    Havenith, George; Zhang, Ping; Hatcher, Kent; Daanen, Hein

    2010-04-01

    Clothing microclimate ventilation is an important parameter in climatic stress and in contaminated environments. The two main methods for its determination (Crockford et al. (CR) 1972 and Lotens and Havenith (LH) 1988) were, after further development, compared in terms of reproducibility, validity and usability. Both methods were shown to have a good sensitivity and reproducibility (with average coefficients of variation 1.5-2.3% for the method alone and up to 7% for method and clothing/movement effects combined). They produced values very close to calibration values in forced ventilation tests (r = 0.988). Weak points for the CR method were the limits in the time constant of the measurement apparatus, causing an upper limit to the ventilation that can be reliably measured (around 800 l/min) and the method of measuring clothing microclimate volume. The original 'vacuum oversuit' (CR) method was cumbersome and prone to large errors. Alternative methods of measuring clothing microclimate volume (whole body scanner or manual circumference measurements) were shown to produce good results. For the LH method, the distribution of the tracer gas over the whole skin surface became a problem factor at very high ventilations (above 1000 l/min). As all methods use tracer gases (O(2), Ar, CO(2), SF(6)) with diffusivities smaller than that of water vapour, this potentially creates a problem in the calculation of vapour resistance from the ventilation values in the region where the emphasis of vapour transfer moves from diffusion to convection. In most real-life situations, where body and air movement are present, a correction is not however required because the error remains below 10%. STATEMENT OF RELEVANCE: Clothing ventilation indicates heat loss potential as well as risk of pollutants entering the clothing. Two main methods for its determination are compared and validated, identifying a number of issues. An in-depth analysis is given of the advantages and disadvantages of

  11. Water risk assessment for river basins in China based on WWF water risk assessment tools

    Directory of Open Access Journals (Sweden)

    N. Wei

    2014-09-01

    Full Text Available Water resource problems, one of the most important environmental and socio-economic issues, have been a common concern worldwide in recent years. Water resource risks are attracting more and more attention from the international community and national governments. Given the current situations of water resources and the water environment, and the characteristics of water resources management and information statistics of China, this paper establishes an index system for water risk assessment in river basins of China based on the index system of water risk assessment proposed by the World Wide Fund For Nature (WWF and German Investment and Development Co., Ltd (DEG. The new system is more suitable for Chinese national conditions and endorses the international assessment index. A variety of factors are considered to determine the critical values of classification for each index, and the indexes are graded by means of 5-grade and 5-score scales; the weights and calculation methods of some indexes are adjusted, with the remaining indexes adopting the method of WWF. The Weighted Comprehensive Index Summation Process is adopted to calculate the integrated assessment score of the river basin. The method is applied to the Haihe River basin in China. The assessment shows that the method can accurately reflect the water risk level of different river basins. Finally, the paper discusses the continuing problems in water risk assessment and points out the research required to provide a reference for further study in this field.

  12. Semiconductor Metal Oxide Sensors in Water and Water Based Biological Systems

    Directory of Open Access Journals (Sweden)

    Marina V. Strobkova

    2003-10-01

    Full Text Available The results of implementation of In2O3-based semiconductor sensors for oxygen concentration evaluation in water and the LB-nutrient media (15.5 g/l Luria Broth Base, Miller (Sigma, Lot-1900 and NaCl without bacteria and with E.coli bacteria before and after UV-irradiation are presented.

  13. Disgust and Shame Based Safe Water and Handwashing Promotion

    Science.gov (United States)

    2015-06-11

    Develop a New Group Version of the Becker-DeGroot-Marsckek (BDM) Auction to Measure Willingness to Pay of Compound Members for Shared Hardware.; Develop a New Survey Instrument to Measure Behavioural Determinants of Hand Washing and Water Treatment Like Disgust and Shame or Social Pressure.; Identify New Methods for Measuring Hand Washing and Water Treatment Behaviour.; Compare the Effectiveness of the Disgust and Shame Based Interventions With Standard Public Health Interventions.

  14. Studies on defluoridation of water by coal-based sorbents

    Energy Technology Data Exchange (ETDEWEB)

    Sivasamy, A.; Singh, K.P.; Mohan, D.; Maruthamuthu, M. [Industrial Toxicology Research Center, Lucknow (India). Environmental Chemical Division

    2001-07-01

    Drinking water containing fluoride above a level of 1 mg dm{sup 3} is considered to be unsafe for human consumption. Defluoridation of water samples by coal-based sorbents was studied at different adsorbent dosages. First-order adsorption rate constants using the Lagergren equation, the Freundlich adsorption isotherm, the Langmuir adsorption isotherm, film diffusion and pore diffusion coefficients have been evaluated for each system. The effect of pH on fluoride removal and the mechanism is also discussed.

  15. Evaluation and Prediction of Water Resources Based on AHP

    Science.gov (United States)

    Li, Shuai; Sun, Anqi

    2017-01-01

    Nowadays, the shortage of water resources is a threat to us. In order to solve the problem of water resources restricted by varieties of factors, this paper establishes a water resources evaluation index model (WREI), which adopts the fuzzy comprehensive evaluation (FCE) based on analytic hierarchy process (AHP) algorithm. After considering influencing factors of water resources, we ignore secondary factors and then hierarchical approach the main factors according to the class, set up a three-layer structure. The top floor is for WREI. Using analytic hierarchy process (AHP) to determine weight first, and then use fuzzy judgment to judge target, so the comprehensive use of the two algorithms reduce the subjective influence of AHP and overcome the disadvantages of multi-level evaluation. To prove the model, we choose India as a target region. On the basis of water resources evaluation index model, we use Matlab and combine grey prediction with linear prediction to discuss the ability to provide clean water in India and the trend of India’s water resources changing in the next 15 years. The model with theoretical support and practical significance will be of great help to provide reliable data support and reference for us to get plans to improve water quality.

  16. Micrometeorological measurements and vapour pressure deficit relations under in-field rainwater harvesting

    Science.gov (United States)

    Tesfuhuney, Weldemichael A.; Walker, Sue; Van Rensburg, Leon D.; Steyn, A. Stephan

    2016-08-01

    In a cropped field, microclimate and thermal stability conditions depend on the canopy structures and the prevailing weather. The main aim of the study therefore was to characterize the vertical profiles of weather variables within and above a maize (Zea mays L.) canopy and to describe the water vapour pressure deficit (VPD) under different atmospheric and soil surface conditions for both wide and narrow runoff strips with the in-field rainwater harvesting (IRWH) system. Micrometeorological measurements of wind, temperature and relative humidity were performed at eight levels, within canopy (1.8 and 2.1 m), and just above the canopy (2.4, 2.7, 3.0, and 3.3 m) up to reference levels (3.9 and 4.5 m) when the maize reached a maximum height of 2.2 m. Under incomplete canopy cover of the IRWH system, two important factors complicated evapotranspiration estimation, namely the local advection and high temperatures of the bare soil between adjacent plant rows. Diurnal variations of water vapour related to turbulence at each locality and its position in the thermal internal boundary layers. Generally, advection was more pronounced in wide runoff strips than narrow strips. On wide runoff strips the wind was more effective in replacing the air between the rows and maintained a higher driving force for evaporation. The maximum VPD over the narrow strips was observed at reference level during a dry day, at about 2.2 kPa in the afternoon, while wet day VPD reached a maximum of 1.8 kPa. The VPD of the wide runoff strips correlated negatively with wind speed, but showed a fairly positive correlation with some scattered values on wet days after rain. Therefore, profile characteristics within and above plant canopies played a key role in determining the VPD and consequently, could help to explain transpiration rates of crops. Hence, VPD relations enhanced the understanding of the heat energy exchange processes under the heterogeneous nature of maize canopy of the IRWH tillage system.

  17. Mixing of multiple metal vapours into an arc plasma in gas tungsten arc welding of stainless steel

    Science.gov (United States)

    Park, Hunkwan; Trautmann, Marcus; Tanaka, Keigo; Tanaka, Manabu; Murphy, Anthony B.

    2017-11-01

    A computational model of the mixing of multiple metal vapours, formed by vaporization of the surface of an alloy workpiece, into the thermal arc plasma in gas tungsten arc welding (GTAW) is presented. The model incorporates the combined diffusion coefficient method extended to allow treatment of three gases, and is applied to treat the transport of both chromium and iron vapour in the helium arc plasma. In contrast to previous models of GTAW, which predict that metal vapours are swept away to the edge of the arc by the plasma flow, it is found that the metal vapours penetrate strongly into the arc plasma, reaching the cathode region. The predicted results are consistent with published measurements of the intensity of atomic line radiation from the metal vapours. The concentration of chromium vapour is predicted to be higher than that of iron vapour due to its larger vaporization rate. An accumulation of chromium vapour is predicted to occur on the cathode at about 1.5 mm from the cathode tip, in agreement with published measurements. The arc temperature is predicted to be strongly reduced due to the strong radiative emission from the metal vapours. The driving forces causing the diffusion of metal vapours into the helium arc are examined, and it is found that diffusion due to the applied electric field (cataphoresis) is dominant. This is explained in terms of large ionization energies and the small mass of helium compared to those of the metal vapours.

  18. Holistic irrigation water management approach based on stochastic soil water dynamics

    Science.gov (United States)

    Alizadeh, H.; Mousavi, S. J.

    2012-04-01

    Appreciating the essential gap between fundamental unsaturated zone transport processes and soil and water management due to low effectiveness of some of monitoring and modeling approaches, this study presents a mathematical programming model for irrigation management optimization based on stochastic soil water dynamics. The model is a nonlinear non-convex program with an economic objective function to address water productivity and profitability aspects in irrigation management through optimizing irrigation policy. Utilizing an optimization-simulation method, the model includes an eco-hydrological integrated simulation model consisting of an explicit stochastic module of soil moisture dynamics in the crop-root zone with shallow water table effects, a conceptual root-zone salt balance module, and the FAO crop yield module. Interdependent hydrology of soil unsaturated and saturated zones is treated in a semi-analytical approach in two steps. At first step analytical expressions are derived for the expected values of crop yield, total water requirement and soil water balance components assuming fixed level for shallow water table, while numerical Newton-Raphson procedure is employed at the second step to modify value of shallow water table level. Particle Swarm Optimization (PSO) algorithm, combined with the eco-hydrological simulation model, has been used to solve the non-convex program. Benefiting from semi-analytical framework of the simulation model, the optimization-simulation method with significantly better computational performance compared to a numerical Mote-Carlo simulation-based technique has led to an effective irrigation management tool that can contribute to bridging the gap between vadose zone theory and water management practice. In addition to precisely assessing the most influential processes at a growing season time scale, one can use the developed model in large scale systems such as irrigation districts and agricultural catchments. Accordingly

  19. Modelling exposure of workers, residents and bystanders to vapour of plant protection products after application to crops.

    Science.gov (United States)

    van den Berg, F; Jacobs, C M J; Butler Ellis, M C; Spanoghe, P; Doan Ngoc, K; Fragkoulis, G

    2016-12-15

    Agricultural use of plant protection products can result in exposure of bystanders, residents, operators and workers. Within the European Union (EU) FP7 project BROWSE, a tool based on a set of models and scenarios has been developed, aiming to assess the risk of exposure of humans to these products. In the present version of the tool only a first conservative tier is available for outdoor vapour exposure assessment. In the vapour exposure evaluation, the target concentrations in air at 10m distance from the edge of a treated field are calculated for specific scenarios for each EU regulatory zone. These scenarios have been selected to represent reasonable worst case volatilisation conditions. The exposure assessment is based on a series of weekly applications in a five year period to cover a wide range of meteorological conditions. The volatilisation from the crop is calculated using the PEARL model and this PEARL output provides the emission strength used as input for the short term version of the atmospheric transport model OPS. The combined PEARL-OPS model is tested against measurements from a field experiment. First results of this test show that the mean concentration level was predicted fairly well. However, sometimes the differences between observations and simulations were found to be substantial. Improvements are suggested for the vapour exposure scenarios as well as for further model development. In the current version of the BROWSE tool a simplified procedure is used to assess single and multiple applications. The actual period of application and the time of application during the day are fixed, and the growth stage of the crop cannot be taken into account. Moreover, competing processes such as penetration of the substance into the plant tissue are not considered. The effect of these factors on the target exposure concentrations is discussed. Copyright © 2016 Elsevier B.V. All rights reserved.

  20. Pump-stopping water hammer simulation based on RELAP5

    Science.gov (United States)

    Yi, W. S.; Jiang, J.; Li, D. D.; Lan, G.; Zhao, Z.

    2013-12-01

    RELAP5 was originally designed to analyze complex thermal-hydraulic interactions that occur during either postulated large or small loss-of-coolant accidents in PWRs. However, as development continued, the code was expanded to include many of the transient scenarios that might occur in thermal-hydraulic systems. The fast deceleration of the liquid results in high pressure surges, thus the kinetic energy is transformed into the potential energy, which leads to the temporary pressure increase. This phenomenon is called water hammer. Generally water hammer can occur in any thermal-hydraulic systems and it is extremely dangerous for the system when the pressure surges become considerably high. If this happens and when the pressure exceeds the critical pressure that the pipe or the fittings along the pipeline can burden, it will result in the failure of the whole pipeline integrity. The purpose of this article is to introduce the RELAP5 to the simulation and analysis of water hammer situations. Based on the knowledge of the RELAP5 code manuals and some relative documents, the authors utilize RELAP5 to set up an example of water-supply system via an impeller pump to simulate the phenomena of the pump-stopping water hammer. By the simulation of the sample case and the subsequent analysis of the results that the code has provided, we can have a better understand of the knowledge of water hammer as well as the quality of the RELAP5 code when it's used in the water-hammer fields. In the meantime, By comparing the results of the RELAP5 based model with that of other fluid-transient analysis software say, PIPENET. The authors make some conclusions about the peculiarity of RELAP5 when transplanted into water-hammer research and offer several modelling tips when use the code to simulate a water-hammer related case.

  1. Metal-Nonmetal Transition and Homogeneous Nucleation of Mercury Vapour

    Science.gov (United States)

    Uchtmann, H.; Rademann, K.; Hensel, F.

    The paper presents ionization potentials of mercury clusters obtained by photoelectron spectroscopy which provide evidence that a size-dependent gradual transition from van der Waals-type to metallic interaction occurs in Hgx-clusters for × > 13. In order to probe the role of this nonmetal to metal transition in the homogeneous nucleation process of supersaturated mercury vapour we have determined the supersaturation necessary for homogeneous condensation of mercury vapour in the temperature range 250 to 320 K. The measurements were made using an upward thermal diffusion cloud chamber. The results demonstrate that none of the current theories for homogeneous nucleation satisfactorily predict the observed critical supersaturations. The measured values are about 3 orders of magnitude lower than the values predicted by the conventional Becker-Döring-Zeldovitch-theory.Translated AbstractMetall-Nichtmetallübergang und homogene Keimbildung bei QuecksilberdampfEs werden photoelektronenspektroskopische Messungen der Ionisationspotentiale von im Molekularstrahl synthetisierten Quecksilberclustern als Funktion der Größe beschrieben. Sie zeigen, daß ein größenabhängiger kontinuierlicher Übergang von van der Waals-Bindung zu metallischer Bindung für Cluster mit mehr als 13 Hg-Atomen auftritt. Um erste Informationen über den Einfluß dieses Übergangs von nichtmetallischem zu metallischem Verhalten auf den Keimbildungsprozeß in übersättigten Quecksilberdämpfen zu erhalten, werden zusätzlich Untersuchungen der homogenen Kondensation von übersättigten Quecksilberdämpfen im Temperaturbereich zwischen 250 bis 320 K mit einer Diffusionsnebelkammer berichtet. Die erhaltenen Ergebnisse können mit keiner der existierenden Theorien für die homogene Kondensation beschrieben werden. Die beobachteten Werte für die die homogene Kondensation auslösende kritische Übersättigung sind um drei Größenordnungen größer als die mit der klassischen Becker

  2. Model-based Extracted Water Desalination System for Carbon Sequestration

    Energy Technology Data Exchange (ETDEWEB)

    Gettings, Rachel; Dees, Elizabeth

    2017-03-23

    The focus of this research effort centered around water recovery from high Total Dissolved Solids (TDS) extracted waters (180,000 mg/L) using a combination of water recovery (partial desalination) technologies. The research goals of this project were as follows: 1. Define the scope and test location for pilot-scale implementation of the desalination system, 2.Define a scalable, multi-stage extracted water desalination system that yields clean water, concentrated brine, and, salt from saline brines, and 3. Validate overall system performance with field-sourced water using GE pre-pilot lab facilities. Conventional falling film-mechanical vapor recompression (FF-MVR) technology was established as a baseline desalination process. A quality function deployment (QFD) method was used to compare alternate high TDS desalination technologies to the base case FF-MVR technology, including but not limited to: membrane distillation (MD), forward osmosis (FO), and high pressure reverse osmosis (HPRO). Technoeconomic analysis of high pressure reverse osmosis (HPRO) was performed comparing the following two cases: 1. a hybrid seawater RO (SWRO) plus HPRO system and 2. 2x standard seawater RO system, to achieve the same total pure water recovery rate. Pre-pilot-scale tests were conducted using field production water to validate key process steps for extracted water pretreatment. Approximately 5,000 gallons of field produced water was processed through, microfiltration, ultrafiltration, and steam regenerable sorbent operations. Improvements in membrane materials of construction were considered as necessary next steps to achieving further improvement in element performance at high pressure. Several modifications showed promising results in their ability to withstand close to 5,000 PSI without gross failure.

  3. A blue/green water-based accounting framework for assessment of water security

    Science.gov (United States)

    Rodrigues, Dulce B. B.; Gupta, Hoshin V.; Mendiondo, Eduardo M.

    2014-09-01

    A comprehensive assessment of water security can incorporate several water-related concepts, while accounting for Blue and Green Water (BW and GW) types defined in accordance with the hydrological processes involved. Here we demonstrate how a quantitative analysis of provision probability and use of BW and GW can be conducted, so as to provide indicators of water scarcity and vulnerability at the basin level. To illustrate the approach, we use the Soil and Water Assessment Tool (SWAT) to model the hydrology of an agricultural basin (291 km2) within the Cantareira Water Supply System in Brazil. To provide a more comprehensive basis for decision making, we analyze the BW and GW-Footprint components against probabilistic levels (50th and 30th percentile) of freshwater availability for human activities, during a 23 year period. Several contrasting situations of BW provision are distinguished, using different hydrological-based methodologies for specifying monthly Environmental Flow Requirements (EFRs), and the risk of natural EFR violation is evaluated by use of a freshwater provision index. Our results reveal clear spatial and temporal patterns of water scarcity and vulnerability levels within the basin. Taking into account conservation targets for the basin, it appears that the more restrictive EFR methods are more appropriate than the method currently employed at the study basin. The blue/green water-based accounting framework developed here provides a useful integration of hydrologic, ecosystem and human needs information on a monthly basis, thereby improving our understanding of how and where water-related threats to human and aquatic ecosystem security can arise.

  4. Durability of silver nanoparticulate films within a silica matrix by flame assisted chemical vapour deposition for biocidal applications.

    Science.gov (United States)

    Cook, Ian; Shee, David W; Foster, Howard A; Varghese, Sajnu

    2011-09-01

    Healthcare acquired infection (HCAI) rates have come under increasing scrutiny in recent years and been a major priority for health professionals in the UK and elsewhere. Of particular concern is the rise of so called 'superbugs', or those resistant to conventional antibiotics, such as Escherichia coli, Clostridium difficile and methicillin resistant Staphylococcus aureus (MRSA). The reasons for this rise are many and complex, but one important factor is bacterial survival rates on wards and other hospital areas. In this respect, nanostructured biocidal surfaces offer a potentially powerful weapon in the fight against HCAI. In addition to providing a toxic environment to a range of infectious disease-causing bacteria (while remaining harmless to human health), any potential bioactive coated surface is required to be durable enough to withstand regular hospital cleaning methods without a reduction in biocidal activity over time and be economically viable to mass produce. The flame assisted chemical vapour deposition (FACVD) of silver and silver/silica films offer a means of producing such surfaces. In this work, we report investigations into a wide range of experimental factors and parameters affecting film durability, including burner head design and relative water vapour content in the flame environment. The produced films were assessed in terms of durability (by scratch testing) and relative silver content using glow discharge optical emission spectroscopy (GDOES).

  5. The development of membrane based high purity oily water separators for use in Arctic waters

    Energy Technology Data Exchange (ETDEWEB)

    Peng, H.; Tremblay, A.Y. [Ottawa Univ., ON (Canada). Dept. of Chemical Engineering, Industrial Membrane Centre; Veinot, D.E. [Defence Research and Development Canada, Halifax, NS (Canada)

    2005-07-01

    With increased exploration and industrial activity in the Canadian Arctic, interest in the Northwest Passage as a shipping route has also increased. The oily wastewater produced by ships must be treated prior to discharge, particularly in the sensitive Arctic environment where biodegradation of organics is very slow due to cold climatic conditions and low sunlight. As such, safe techniques are needed for the treatment of oily wastewater released from ships. However, bilge water is difficult to treat because it contains seawater, particulates, used oils and detergents. Membrane based oily water separators (OWS) are considered to be a key technology for the treatment of bilge water onboard ships. The issues that must be taken into account in the ship-born use of membrane based OWS include the proper treatment of the oily brine before discharge; the substantial reduction in volume that is required; the complexity of the technology; labour associated with the operation of the system due to filter changes and cleaning; and, system automation to simplify its operation. In this study, a membrane-based process for treating bilge water was developed to meet stringent discharge regulations for discharge in Arctic waters. Currently, this discharge limit is set at 0 ppm. A pilot scale membrane cascade system was designed and evaluated. Multilumen ceramic membranes were used in the first stage and Sepa{sup R} test cells were used in the second stage. Optimal membrane pore size was determined. The study investigated the separation of oil and grease using different molecular weight cut-off (MWCO) membranes. The study revealed that through proper membrane design, it is possible to remove oil and grease from bilge water to a level permitting its discharge to Arctic waters. However, it was recommended that low level aromatic diesel fuels be used in ships operating in Arctic waters since the presence of soluble aromatics in diesel fuel increases the technical difficulty of reaching

  6. Subscale Water Based Phase Change Material Heat Exchanger Development

    Science.gov (United States)

    Sheth, Rubik; Hansen, Scott

    2016-01-01

    Supplemental heat rejection devices are required in many spacecraft as the radiators are not sized to meet the full heat rejection demand. One means of obtaining additional heat rejection is through the use of phase change material heat exchangers (PCM HX's). PCM HX's utilize phase change to store energy in unfavorable thermal environments (melting) and reject the energy in favorable environments (freezing). Traditionally, wax has been used as a PCM on spacecraft. However, water is an attractive alternative because it is capable of storing about 40% more energy per unit mass due to its higher latent heat of fusion. The significant problem in using water as a PCM is its expansion while freezing, leading to structural integrity concerns when housed in an enclosed heat exchanger volume. Significant investigation and development has taken place over the past five years to understand and overcome the problems associated with water PCM HX's. This paper reports on the final efforts by Johnson Space Center's Thermal Systems Branch to develop a water based PCM HX. The test article developed and reported on is a subscale version of the full-scale water-based PCM HX's constructed by Mezzo Technologies. The subscale unit was designed by applying prior research on freeze front propagation and previous full-scale water PCM HX development. Design modifications to the subscale unit included use of urethane bladder, decreased aspect ratio, perforated protection sheet, and use of additional mid-plates. Testing of the subscale unit was successful and 150 cycles were completed without fail.

  7. Water resource requirements of corn-based ethanol

    Science.gov (United States)

    Mubako, Stanley; Lant, Christopher

    2008-07-01

    Ethanol derived from fermentation of corn is a very water-intensive product with water to ethanol mass ratios of 927 to 1178 and volumetric ratios of 1174 to 1492 for the major rainfed corn-growing U.S. states of Illinois and Iowa and the leading irrigated corn-growing state of Nebraska, respectively. Over 99% of water requirements are for growing corn feed stocks, with 99% of that amount in Illinois and Iowa, occurring as evapotranspiration of rainfall in corn fields, and 60% as evapotranspiration of applied irrigation water in Nebraska. As a rough measure of water quality impacts, 65.5 g N, 23.8 g P, and 1.03 g of pesticides are applied, and 4.8 kg of soil is eroded per liter of ethanol produced. These results add to knowledge on corn-based ethanol's low net energy balance and high carbon footprint by demonstrating the high water resource intensity of corn-based ethanol production.

  8. Hydrogen Production from Semiconductor-based Photocatalysis via Water Splitting

    Directory of Open Access Journals (Sweden)

    Jeffrey C. S. Wu

    2012-10-01

    Full Text Available Hydrogen is the ideal fuel for the future because it is clean, energy efficient, and abundant in nature. While various technologies can be used to generate hydrogen, only some of them can be considered environmentally friendly. Recently, solar hydrogen generated via photocatalytic water splitting has attracted tremendous attention and has been extensively studied because of its great potential for low-cost and clean hydrogen production. This paper gives a comprehensive review of the development of photocatalytic water splitting for generating hydrogen, particularly under visible-light irradiation. The topics covered include an introduction of hydrogen production technologies, a review of photocatalytic water splitting over titania and non-titania based photocatalysts, a discussion of the types of photocatalytic water-splitting approaches, and a conclusion for the current challenges and future prospects of photocatalytic water splitting. Based on the literatures reported here, the development of highly stable visible–light-active photocatalytic materials, and the design of efficient, low-cost photoreactor systems are the key for the advancement of solar-hydrogen production via photocatalytic water splitting in the future.

  9. Sea Water Intrusion in Kaligawe Semarang Based on Resistivity Data

    Science.gov (United States)

    Setyawan, Agus; Najib; Aribowo, Yoga; Trihadini, Agnis; Hastuti, Dhana; Ramdhani, Fitra; Waskito, Fajar; Febrika, Ganap; Virgiawan, Galang

    2017-02-01

    Semarang is a city on the north coast of the island of Java, Indonesia and it is lowland areas have experienced sea water intrusion. One of interesting area is Kaligawe which located at Eastern part of Semarang. Kaligawe has big population and industrial and it need water consumption. Excessive extraction of groundwater will be resulting height difference surface ground water to the surface of the sea water due to sea water intrusion. Electric resistivity method was used to detect for salt water intrusion. Dipole-dipole configuration was applied with 3 lines to get current, potential difference, and apparent resistivity from the field. 2D model has presented using Res2Dinv to get the true resistivity and the depth of each layer. A calibration of the model was conducted based on geological information. Result showed the subsurface area has 4 layers: sandstone, sandsilt, siltstone and clay. Moreover the sea water intrusion occurs in the Northwest, East and Southern part of the study area

  10. Tantalum-based semiconductors for solar water splitting.

    Science.gov (United States)

    Zhang, Peng; Zhang, Jijie; Gong, Jinlong

    2014-07-07

    Solar energy utilization is one of the most promising solutions for the energy crises. Among all the possible means to make use of solar energy, solar water splitting is remarkable since it can accomplish the conversion of solar energy into chemical energy. The produced hydrogen is clean and sustainable which could be used in various areas. For the past decades, numerous efforts have been put into this research area with many important achievements. Improving the overall efficiency and stability of semiconductor photocatalysts are the research focuses for the solar water splitting. Tantalum-based semiconductors, including tantalum oxide, tantalate and tantalum (oxy)nitride, are among the most important photocatalysts. Tantalum oxide has the band gap energy that is suitable for the overall solar water splitting. The more negative conduction band minimum of tantalum oxide provides photogenerated electrons with higher potential for the hydrogen generation reaction. Tantalates, with tunable compositions, show high activities owning to their layered perovskite structure. (Oxy)nitrides, especially TaON and Ta3N5, have small band gaps to respond to visible-light, whereas they can still realize overall solar water splitting with the proper positions of conduction band minimum and valence band maximum. This review describes recent progress regarding the improvement of photocatalytic activities of tantalum-based semiconductors. Basic concepts and principles of solar water splitting will be discussed in the introduction section, followed by the three main categories regarding to the different types of tantalum-based semiconductors. In each category, synthetic methodologies, influencing factors on the photocatalytic activities, strategies to enhance the efficiencies of photocatalysts and morphology control of tantalum-based materials will be discussed in detail. Future directions to further explore the research area of tantalum-based semiconductors for solar water splitting

  11. Sensing response of copper phthalocyanine salt dispersed glass with organic vapours

    Energy Technology Data Exchange (ETDEWEB)

    Ridhi, R.; Sachdeva, Sheenam; Saini, G. S. S.; Tripathi, S. K., E-mail: surya@pu.ac.in [Department of Physics, Center of Advanced Study in Physics, Panjab University, Chandigarh-160 014 (INDIA) Fax: +91-172-2783336; Tel.:+91-172-2544362 (India)

    2016-05-06

    Copper Phthalocyanine and other Metal Phthalocyanines are very flexible and tuned easily to modify their structural, spectroscopic, optical and electrical properties by either functionalizing them with various substituent groups or by replacing or adding a ligand to the central metal atom in the phthalocyanine ring and accordingly can be made sensitive and selective to various organic species or gaseous vapours. In the present work, we have dispersed Copper Phthalocyanine Salt (CuPcS) in sol-gel glass form using chemical route sol-gel method and studied its sensing mechanism with organic vapours like methanol and benzene and found that current increases onto their exposure with vapours. A variation in the activation energies was also observed with exposure of vapours.

  12. Pervaporation and vapour permeation of methanol and MTBE through a microporous methylated silica membrane

    NARCIS (Netherlands)

    de Bruijn, F.T.

    2006-01-01

    The combination of conventional unit operations with pervaporation or vapour permeation membrane separation processes offers opportunities for process intensification in terms of augmenting capacity and decreasing energy consumption of conventional unit operations. The MTBE production process is an

  13. Modelling of vapour explosion in stratified geometrie; Modelisation de l'explosion de vapeur en geometrie stratifiee

    Energy Technology Data Exchange (ETDEWEB)

    Picchi, St

    1999-07-07

    When a hot liquid comes into contact with a colder volatile liquid, one can obtain in some conditions an explosive vaporization, told vapour explosion, whose consequences can be important on neighbouring structures. This explosion needs the intimate mixing and the fine fragmentation between the two liquids. In a stratified vapour explosion, these two liquids are initially superposed and separated by a vapor film. A triggering of the explosion can induce a propagation of this along the film. A study of experimental results and existent models has allowed to retain the following main points: - the explosion propagation is due to a pressure wave propagating through the medium; - the mixing is due to the development of Kelvin-Helmholtz instabilities induced by the shear velocity between the two liquids behind the pressure wave. The presence of the vapour in the volatile liquid explains experimental propagation velocity and the velocity difference between the two fluids at the pressure wave crossing. A first model has been proposed by Brayer in 1994 in order to describe the fragmentation and the mixing of the two fluids. Results of the author do not show explosion propagation. We have therefore built a new mixing-fragmentation model based on the atomization phenomenon that develops itself during the pressure wave crossing. We have also taken into account the transient aspect of the heat transfer between fuel drops and the volatile liquid, and elaborated a model of transient heat transfer. These two models have been introduced in a multi-components, thermal, hydraulic code, MC3D. Results of calculation show a qualitative and quantitative agreement with experimental results and confirm basic options of the model. (author)

  14. Laser diagnostics of chemical vapour deposition of diamond films

    CERN Document Server

    Wills, J B

    2002-01-01

    Cavity ring down spectroscopy (CRDS) has been used to make diagnostic measurements of chemically activated CH sub 4 / H sub 2 gas mixtures during the chemical vapour deposition (CVD) of thin diamond films. Absolute absorbances, concentrations and temperatures are presented for CH sub 3 , NH and C sub 2 H sub 2 in a hot filament (HF) activated gas mixture and CH, C sub 2 and C sub 2 H sub 2 in a DC arc plasma jet activated mixture. Measurements of the radical species were made using a pulsed dye laser system to generate tuneable visible and UV wavelengths. These species have greatest concentration in the hottest, activated regions of the reactors. Spatial profiling of the number densities of CH sub 3 and NH radicals have been used as stringent tests of predictions of radical absorbance and number densities made by 3-D numerical simulations, with near quantitative agreement. O sub 2 has been shown to reside in the activated region of the Bristol DC arc jet at concentrations (approx 10 sup 1 sup 3 molecules / cm...

  15. Chemical vapour deposition of diamond coatings onto molybdenum dental tools

    Science.gov (United States)

    Amar, M.; Ahmed, W.; Sein, H.; Jones, A. N.; Rego, C. A.

    2003-10-01

    The growth of polycrystalline diamond films onto molybdenum rods and dental burrs by using a new hot filament chemical vapour deposition (CVD) system has been investigated. Negative dc bias voltage relative to the filament was applied to the molybdenum substrate prior to deposition. This led to much improved film adhesion and increased nucleation density. There was a factor of four improvement in the adhesive force from 20 to 80 N when a bias voltage of -300 V was employed to the substrate. The CVD coated molybdenum dental burr was found to give much improved performance and lifetime compared to the conventional sintered diamond burr. The CVD diamond burr showed no signs of deterioration even after 1000 operations whereas the conventional sintered diamond burrs were ineffective after between 30 and 60 operations. This represents a 30-fold improvement when CVD is applied. CVD diamond growth onto dental burrs has the potential for replacing exciting technology by achieving better performance and lifetime in a cost-effective manner.

  16. Poly(methyl methacrylate) films for organic vapour sensing

    CERN Document Server

    Capan, R; Hassan, A K; Tanrisever, T

    2003-01-01

    Optical constants and fabrication parameters are investigated using surface plasmon resonance (SPR) studies on spun films of poly(methyl methacrylate) (PMMA) derivatives in contact with two different dielectric media. A value of 1.503 for the refractive index of PMMA films produced from a solution having concentration of 1 mg ml sup - sup 1 at the speed of 3000 rpm is in close agreement with the data obtained from ellipsometric measurements. The film thickness shows a power-law dependence on the spin speed but the thickness increases almost linearly with the concentration of the spreading solution. These results are in good agreement with the hydrodynamic theory for a low-viscosity and highly volatile liquid. On the basis of SPR measurements under dynamic conditions, room temperature response of PMMA films to benzene vapours is found to be fast, highly sensitive and reversible. The sensitivity of detection of toluene, ethyl benzene and m-xylene is much smaller than that of benzene.

  17. The atmospheric chemical vapour deposition of coatings on glass

    CERN Document Server

    Sanderson, K D

    1996-01-01

    The deposition of thin films of indium oxide, tin doped indium oxide (ITO) and titanium nitride for solar control applications have been investigated by Atmospheric Chemical Vapour Deposition (APCVD). Experimental details of the deposition system and the techniques used to characterise the films are presented. Results from investigations into the deposition parameters, the film microstructure and film material properties are discussed. A range of precursors were investigated for the deposition of indium oxide. The effect of pro-mixing the vaporised precursor with an oxidant source and the deposition temperature has been studied. Polycrystalline In sub 2 O sub 3 films with a resistivity of 1.1 - 3x10 sup - sup 3 OMEGA cm were obtained with ln(thd) sub 3 , oxygen and nitrogen. The growth of ITO films from ln(thd) sub 3 , oxygen and a range of tin dopants is also presented. The effect of the dopant precursor, the doping concentration, deposition temperature and the effect of additives on film growth and microstr...

  18. The characteristics of a vapour bubble moving in a non-uniform flow field

    Science.gov (United States)

    Hangen, Ni; Jianbo, Huang

    1986-08-01

    The present paper describes the dynamic process of a vapour bubble moving in a non-uniform flow field. The coupling between the bubble moving as a whole and the deformation of the bubble surface is considered. The effect of the pressure gradient on the bubble movement is analysed. For a given flow field the numerical calculation is carried out until the vapour bubble is split by a micro-jet.

  19. A Cascade-Based Emergency Model for Water Distribution Network

    Directory of Open Access Journals (Sweden)

    Qing Shuang

    2015-01-01

    Full Text Available Water distribution network is important in the critical physical infrastructure systems. The paper studies the emergency resource strategies on water distribution network with the approach of complex network and cascading failures. The model of cascade-based emergency for water distribution network is built. The cascade-based model considers the network topology analysis and hydraulic analysis to provide a more realistic result. A load redistribution function with emergency recovery mechanisms is established. From the aspects of uniform distribution, node betweenness, and node pressure, six recovery strategies are given to reflect the network topology and the failure information, respectively. The recovery strategies are evaluated with the complex network indicators to describe the failure scale and failure velocity. The proposed method is applied by an illustrative example. The results showed that the recovery strategy considering the node pressure can enhance the network robustness effectively. Besides, this strategy can reduce the failure nodes and generate the least failure nodes per time.

  20. Estimating Evapotranspiration Using an Observation Based Terrestrial Water Budget

    Science.gov (United States)

    Rodell, Matthew; McWilliams, Eric B.; Famiglietti, James S.; Beaudoing, Hiroko K.; Nigro, Joseph

    2011-01-01

    Evapotranspiration (ET) is difficult to measure at the scales of climate models and climate variability. While satellite retrieval algorithms do exist, their accuracy is limited by the sparseness of in situ observations available for calibration and validation, which themselves may be unrepresentative of 500m and larger scale satellite footprints and grid pixels. Here, we use a combination of satellite and ground-based observations to close the water budgets of seven continental scale river basins (Mackenzie, Fraser, Nelson, Mississippi, Tocantins, Danube, and Ubangi), estimating mean ET as a residual. For any river basin, ET must equal total precipitation minus net runoff minus the change in total terrestrial water storage (TWS), in order for mass to be conserved. We make use of precipitation from two global observation-based products, archived runoff data, and TWS changes from the Gravity Recovery and Climate Experiment satellite mission. We demonstrate that while uncertainty in the water budget-based estimates of monthly ET is often too large for those estimates to be useful, the uncertainty in the mean annual cycle is small enough that it is practical for evaluating other ET products. Here, we evaluate five land surface model simulations, two operational atmospheric analyses, and a recent global reanalysis product based on our results. An important outcome is that the water budget-based ET time series in two tropical river basins, one in Brazil and the other in central Africa, exhibit a weak annual cycle, which may help to resolve debate about the strength of the annual cycle of ET in such regions and how ET is constrained throughout the year. The methods described will be useful for water and energy budget studies, weather and climate model assessments, and satellite-based ET retrieval optimization.

  1. Measuring and Classifying Land-Based and Water-Based Daily Living Activities Using Inertial Sensors

    Directory of Open Access Journals (Sweden)

    Koichi Kaneda

    2018-02-01

    Full Text Available This study classified motions of typical daily activities in both environments using inertial sensors attached at the chest and thigh to determine the optimal site to attach the sensors. Walking, chair standing and sitting, and step climbing were conducted both in water and on land. A mean, variance and skewness for acceleration data was calculated. A Neural Network and Decision Tree algorithm was applied for classifying each motion in both environments. In total, 126 and 144 samples of thigh and chest data sets were obtained for analysis in each condition. For the chest data, the algorithm correctly classified 80% of the water-based activities, and 90% of the land-based. Whilst the thigh sensor correctly classified 97% of water-based and 100% of land-based activities. The inertial sensor placed on the thigh provided the most appropriate protocol for classifying motions for land-based and water-based typical daily life activities.

  2. Radar Based Flow and Water Level Forecasting in Sewer Systems

    DEFF Research Database (Denmark)

    Thorndahl, Søren; Rasmussen, Michael R.; Grum, M.

    2009-01-01

    This paper describes the first radar based forecast of flow and/or water level in sewer systems in Denmark. The rainfall is successfully forecasted with a lead time of 1-2 hours, and flow/levels are forecasted an additional ½-1½ hours using models describing the behaviour of the sewer system. Both...

  3. Estimate of Water Residence Times in Tudor Creek, Kenya Based ...

    African Journals Online (AJOL)

    for tide gauge (MTl-S) and recording current meter deployments (RCM) and for the site of the weather mast (KMFRI). Meteorological Department station data on rainfall, amongst others. Calculations of water exchange are based on heat and salt conservation, applied during periods of dry and wet climate, respectively.

  4. Radio Frequency Based Water Level Monitor and Controller for ...

    African Journals Online (AJOL)

    This paper elucidates a radio frequency (RF) based transmission and reception system used to remotely monitor and control the water Level of an overhead tank placed up to 100 meters away from the pump and controller. It uses two Radio Frequency transceivers along with a controller each installed at the overhead tank ...

  5. WATGIS: A GIS-Based Lumped Parameter Water Quality Model

    Science.gov (United States)

    Glenn P. Fernandez; George M. Chescheir; R. Wayne Skaggs; Devendra M. Amatya

    2002-01-01

    A Geographic Information System (GIS)­based, lumped parameter water quality model was developed to estimate the spatial and temporal nitrogen­loading patterns for lower coastal plain watersheds in eastern North Carolina. The model uses a spatially distributed delivery ratio (DR) parameter to account for nitrogen retention or loss along a drainage network. Delivery...

  6. Hierarchical clustering of RGB surface water images based on MIA ...

    African Journals Online (AJOL)

    This database, compiled from digital photographs of the various water levels and similar images of surface areas and vegetation, was transferred into an image matrix, and reorganised by means of principal component analysis (PCA) based on singular value decomposition (SVD). The high dimensionality of original images ...

  7. Estimate of Water Residence Times in Tudor Creek, Kenya Based ...

    African Journals Online (AJOL)

    However, even though the observed salinity gradient in the creek appeared consistent with dry and rain periods, estimates of river runoffs were not good enough to calculate water exchange, based on salt conservation. Runoff in general was also too small to give reliable rating curves (correlation between rainfall and river ...

  8. Performance investigation of vapour recompressed batch distillation for separating ternary wide boiling constituents

    Directory of Open Access Journals (Sweden)

    Rohith R Nair

    2017-12-01

    Full Text Available The vapour recompression scheme (VRC has been very effective in continuous distillation for energy intensification. The applicability of this scheme for the separation of multicomponent wide boiling constituents in batch distillation is a major challenge, because of the unsteady nature of the batch. In this study, the vapour recompression scheme has been implemented for the separation of multicomponent wide boiling constituents in the batch distillation. For the optimal usage of energy from compressed vapours manipulation of top tray vapour or external energy is done. A comparative study of the vapour recompressed batch distillation having a variable speed single compressor (SVRBD and double stage compressor (DVRBD with conventional batch distillation in terms of energy savings and total annualized cost is done. The VRC schemes achieve an energy savings of 50% and 10.03% total annualized cost (TAC for SVRBD and DVRBD achieve 52% energy savings and 12.21% TAC with a payback period of 10 years. Keywords: Batch distillation, Vapour recompression, Wide boiling constituents, Energy saving, Total annualized cost

  9. Immunological disorders in men exposed to metallic mercury vapour. A review.

    Science.gov (United States)

    Moszczyński, P

    1999-02-01

    The awareness of the effects of metallic mercury vapour on the human immune system has increased only in the last decade. The regulatory guidelines relating to testing for immunotoxicity of metals are not standardized so far. A full understanding of the relevance of the tests to man is still incomplete. Immunotoxicity investigation of metals in rodents, with subsequent extrapolation to man, forms the basis of human risk assessment. Human contact with mercury vapour is mainly in chloralkali plants and in factories producing controlling and measuring devices. When the immune system acts as a target of xenobiotic insults, the result can be a decreased resistance to infection, cancers, or immune disregulation that can induce the development of allergy, or autoimmunity (Fig. 1). This article reviews literature data and our studies concerning the immunotoxicity of metallic mercury vapour. A number of data shows that mercury exerts a suppressing effect but another data suggest stimulating effects on the human immune system. The results of immunological monitoring of individuals exposed to mercury vapour were either positive or negative as well as borderline and uncertain as to the influence of mercury vapour on human immune system. The positive data had no influence on the resistance of workers to infections and neoplasms. Skin and mucosa hypersensitivity to metallic mercury is rare. No positive report that mercury vapour could be carcinogenic in man has appeared up to now.

  10. Comparison of tanker drivers' occupational exposures before and after the installation of a vapour recovery system.

    Science.gov (United States)

    Saarinen, L; Hakkola, M; Kangas, J

    2000-12-01

    The purpose of this study was to compare tanker drivers' occupational exposure level before and after the installation of vapour recovery facilities at 14 service stations. Road tanker drivers are exposed when handling volatile petrol liquid in bulk in the distribution chain. The drivers' exposure was studied during the unloading operation as the bulk petrol flowed into underground storage tanks, displacing vapours in the tank space and causing emission to the environment and the drivers' work area. The exposures were measured again when the dual point Stage I vapour recovery systems were installed for recycling vapours. Short-term measurements were carried out in the drivers' breathing zones by drawing polluted air through a charcoal tube during unloading. The samples were analysed in the laboratory by gas chromatography for C3-C11 aliphatic hydrocarbons, tert-butyl methyl ether (MTBE), tert-amyl methyl ether (MTAE), benzene, toluene and xylene. The road tanker loads delivered consisted of oxygenated and reformulated petrol (E95 and E98 brands), which contained on average 13% oxygenates. Before the installation of the vapour recovery system, the geometric mean (GM) concentration of aliphatic hydrocarbons was 65 mg m-3 (range 6-645 mg m-3) in the drivers' breathing zones. After the installation at the same service stations, the corresponding exposure level was 8.3 mg m-3 (range tankers without and with vapour recovery were statistically significant (p < 0.05).

  11. Structural and luminescence properties of vapour-etched porous silicon and related compounds

    Energy Technology Data Exchange (ETDEWEB)

    Aouida, S.; Saadoun, M.; Saad, K. Ben; Bessais, B. [Institut National de Recherche Scientifique et Technique, Laboratoire de Photovoltaique et des Semiconducteurs, BP 95, 2050 Hammam- Lif (Tunisia)

    2005-06-01

    Porous silicon (PS) is usually prepared by the electrochemical anodization or the stain etching techniques. Recently, a new method consisting of exposing silicon substrates to acid vapours issued from a mixture of HNO{sub 3}/HF was employed to generate highly luminescent PS layers. The so-called HNO{sub 3}/HF vapour etching (VE) technique can be easily applied in various large area of silicon-based devices. Depending on the HNO{sub 3}/HF volume ratio, we found that VE silicon results in the formation of PS and/or a luminescent (NH{sub 4}){sub 2}SiF{sub 6} powder-like phase. FTIR spectra of VE-based PS layers formed at HNO{sub 3}/HF volume ratio ranging between 1/100-1/3 contain N-H and Si-F bonds related to NH{sub 4}{sup +} and SiF{sub 6}{sup 2-} ions in addition to the conventional SiH{sub x} species. These nitride and fluoride groups were identified to be associated to the (NH{sub 4}){sub 2}SiF{sub 6} powder-like phase which in turn contains small Si nanoparticles embedded in a SiO{sub x} matrix. The presence of such structures was explained as being the product of the VE technique itself. For vapours rich in HNO{sub 3} (HNO{sub 3}/HF volume ratio >1/4), the VE method can produce almost only the luminescent (NH{sub 4}){sub 2}SiF{sub 6} compound. The VE-based PS is essentially composed of dot-like Si particles with sizes not exceeding 5 nm and emitting a photoluminescence (PL) band around 1.93 eV. The PL band of the VE-based PS presents a shoulder at 2.09 eV, which becomes more significant after oxidation in air. This shoulder at 2.09 eV was attributed to an excitonic emission from the energy levels of the SiO{sub x} surrounding the smallest Si nanocrystallites. The PL band emission of the (NH{sub 4}){sub 2}SiF{sub 6} powder presents two peaks. The first one was attributed to Si nanocrystallites emitting at 1.98 eV. The second peak could be associated to the smallest nanocrystallites ({<=}1.5 nm). For these crystallites, excitons are trapped on the SiO{sub x

  12. Performance of A Vapour Compression Heat Pump System Using A Nonazeotropic Refrigerant Mixture

    Science.gov (United States)

    Goto, Masao; Kanbe, Kouji; Sakai, Takanori; Inoue, Norihiro

    An experimental study of the performance of a vapour compression heat pump system using a HCFC22 and CFC114 mixture of 20, 40, 60 and 100 mass% of HCFC22 as a working fluid was carried out. Heat Transfer characteristics of the condenser and the evaporator were also investigated. The condenser and the evaporator were counter flow heat exchangers with a smooth copper tube of 12 mmID and 8 m length. The experiments were performed under the conditions that the flow rates of the heat source and sink water and their inlet temperatures of the heat exchangers were kept constant, maintaining the constant evaporating temperature at the inlet of the evaporater. The results indicate that the coefficients of performance (COP) in case of the mixtures are about 45% higher than that of pure HCFC22 in the range of CFC1l4 mass fraction from 0.6 to 0.8 and the effect of the composition of mixtures on COP is well agreement with that obtained from the thermodynamic cycle analysis. Overall heat transfer coefficient of mixtures decreases with increasing CFC114 mass fraction of the mixture and the empirical correlation for the effect of the composion of the mixture on condensation heat transfer is obtained.

  13. The scientific base of heating water by microwave

    Science.gov (United States)

    Akdoǧan, Ender; ćiftçi, Muharrem

    2016-03-01

    This article is based on the master thesis [4] related to our invention which was published in World Intellectual Property Organization (WO/2011/048506) as a microwave water heater. In the project, a prototype was produced to use microwave in industrial heating. In order to produce the prototype, the most appropriate material kind for microwave-water experiments was determined by a new energy loss rate calculation technique. This new energy loss calculation is a determinative factor for material permeability at microwave frequency band (1-100 GHz). This experimental series aim to investigate the rationality of using microwave in heating industry. Theoretically, heating water by microwave (with steady frequency 2.45 GHz) is analyzed from sub-molecular to Classical Mechanic results of heating. In the study, we examined Quantum Mechanical base of heating water by microwave experiments. As a result, we derived a Semi-Quantum Mechanical equation for microwave-water interactions and thus, Wien displacement law can be derived to verify experimental observations by this equation.

  14. The scientific base of heating water by microwave

    Energy Technology Data Exchange (ETDEWEB)

    Akdoğan, Ender, E-mail: ender.akdogan@tpe.gov.tr [Department of Physics Engineering, Ankara University, Dögol St. Tandoğan Ankara 06560 Türkiye (Turkey); Çiftçi, Muharrem, E-mail: muharrem-ciftci@windowslive.com [Author" 1 Department of Physics, Ankara University, Dögol St. Tandoğan Ankara 06560 Türkiye (Turkey)

    2016-03-25

    This article is based on the master thesis [4] related to our invention which was published in World Intellectual Property Organization (WO/2011/048506) as a microwave water heater. In the project, a prototype was produced to use microwave in industrial heating. In order to produce the prototype, the most appropriate material kind for microwave-water experiments was determined by a new energy loss rate calculation technique. This new energy loss calculation is a determinative factor for material permeability at microwave frequency band (1-100 GHz). This experimental series aim to investigate the rationality of using microwave in heating industry. Theoretically, heating water by microwave (with steady frequency 2.45 GHz) is analyzed from sub-molecular to Classical Mechanic results of heating. In the study, we examined Quantum Mechanical base of heating water by microwave experiments. As a result, we derived a Semi-Quantum Mechanical equation for microwave-water interactions and thus, Wien displacement law can be derived to verify experimental observations by this equation.

  15. Structure and Dynamics of Water at Carbon-Based Interfaces

    Directory of Open Access Journals (Sweden)

    Jordi Martí

    2017-03-01

    Full Text Available Water structure and dynamics are affected by the presence of a nearby interface. Here, first we review recent results by molecular dynamics simulations about the effect of different carbon-based materials, including armchair carbon nanotubes and a variety of graphene sheets—flat and with corrugation—on water structure and dynamics. We discuss the calculations of binding energies, hydrogen bond distributions, water’s diffusion coefficients and their relation with surface’s geometries at different thermodynamical conditions. Next, we present new results of the crystallization and dynamics of water in a rigid graphene sieve. In particular, we show that the diffusion of water confined between parallel walls depends on the plate distance in a non-monotonic way and is related to the water structuring, crystallization, re-melting and evaporation for decreasing inter-plate distance. Our results could be relevant in those applications where water is in contact with nanostructured carbon materials at ambient or cryogenic temperatures, as in man-made superhydrophobic materials or filtration membranes, or in techniques that take advantage of hydrated graphene interfaces, as in aqueous electron cryomicroscopy for the analysis of proteins adsorbed on graphene.

  16. Water-wire catalysis in photoinduced acid-base reactions.

    Science.gov (United States)

    Kwon, Oh-Hoon; Mohammed, Omar F

    2012-07-07

    The pronounced ability of water to form a hyperdense hydrogen (H)-bond network among itself is at the heart of its exceptional properties. Due to the unique H-bonding capability and amphoteric nature, water is not only a passive medium, but also behaves as an active participant in many chemical and biological reactions. Here, we reveal the catalytic role of a short water wire, composed of two (or three) water molecules, in model aqueous acid-base reactions synthesizing 7-hydroxyquinoline derivatives. Utilizing femtosecond-resolved fluorescence spectroscopy, we tracked the trajectories of excited-state proton transfer and discovered that proton hopping along the water wire accomplishes the reaction more efficiently compared to the transfer occurring with bulk water clusters. Our finding suggests that the directionality of the proton movements along the charge-gradient H-bond network may be a key element for long-distance proton translocation in biological systems, as the H-bond networks wiring acidic and basic sites distal to each other can provide a shortcut for a proton in searching a global minimum on a complex energy landscape to its destination.

  17. Charge-based forces at the Nafion-water interface.

    Science.gov (United States)

    Das, Ronnie; Pollack, Gerald H

    2013-02-26

    Interfacial water lying next to hydrophilic surfaces has been shown to be spectroscopically, mechanically, and electrically distinct from bulk water. Interfacial water has also been shown to exclude negatively and positively charged microspheres and has thus become known as the "exclusion zone". Measurements have demonstrated that exclusion zones exhibit a negative electrical potential on the order of -100 mV relative to bulk water, with a corresponding distribution of positive protons in the bulk water region beyond the exclusion zone. This separation of charge is hypothesized to create an electrostatic force between the exclusion zone and the proton-enriched zone beyond. To test this hypothesis, a hydrophilic Nafion ring was attached to the tip of a deflectable ribbonlike force sensor. The sensor was designed to obstruct the flow of protons from one side of the lever to the other, so that any proton-based force would remain unilateral. pH-sensitive dye measurements confirmed that the protons were largely confined to one side. When the lever assembly was exposed to water, the sensor deflected toward the protons. Over a period of 20 min, deflection amounted to approximately 20 μm, corresponding to a force of approximately 22 μN. Hence, electrostatic forces are confirmed. If exclusion zones exist ubiquitously at hydrophilic surfaces, including biological surfaces, then the resulting electrostatic forces may play significant roles in many biological phenomena including adhesion and protein folding.

  18. Dynamics of Encapsulation and Controlled Release Systems Based on Water-in-Water Emulsions: Negligible Surface Rheology

    NARCIS (Netherlands)

    Sagis, L.M.C.

    2008-01-01

    A nonequilibrium thermodynamic model based on the interfacial transport phenomena (ITP) formalism was used to study deformation¿relaxation behavior of water-in-water emulsions. The ITP formalism allows us to describe all water-in-water emulsions with one single theory. Phase-separated biopolymer

  19. Integrated Water Hazards Engineering Based on Mapping, Nature-Based and Technical Solutions

    Science.gov (United States)

    Halbac-Cotoara-Zamfir, Rares; Herban, Sorin; Stolte, Jannes; Bozan, Csaba

    2017-10-01

    Climate change is expected to alter average temperature and precipitation values and to increase the variability of precipitation events, which may lead to even more intense and frequent water hazards. Water hazards engineering is the branch of engineering concerned with the application of scientific and engineering principles for protection of human populations from the effects of water hazards; protection of environments, both local and global, from the potentially deleterious effects of water hazards; and improvement of environmental quality for mitigating the negative effects of water hazards. An integrated approach of water hazards engineering based on mapping, nature-based and technical solutions will constitute a feasible solution in the process of adapting to challenges generated by climate changes worldwide. This paper will debate this concept also providing some examples from several European countries.

  20. Development of Ensemble Model Based Water Demand Forecasting Model

    Science.gov (United States)

    Kwon, Hyun-Han; So, Byung-Jin; Kim, Seong-Hyeon; Kim, Byung-Seop

    2014-05-01

    In recent years, Smart Water Grid (SWG) concept has globally emerged over the last decade and also gained significant recognition in South Korea. Especially, there has been growing interest in water demand forecast and optimal pump operation and this has led to various studies regarding energy saving and improvement of water supply reliability. Existing water demand forecasting models are categorized into two groups in view of modeling and predicting their behavior in time series. One is to consider embedded patterns such as seasonality, periodicity and trends, and the other one is an autoregressive model that is using short memory Markovian processes (Emmanuel et al., 2012). The main disadvantage of the abovementioned model is that there is a limit to predictability of water demands of about sub-daily scale because the system is nonlinear. In this regard, this study aims to develop a nonlinear ensemble model for hourly water demand forecasting which allow us to estimate uncertainties across different model classes. The proposed model is consist of two parts. One is a multi-model scheme that is based on combination of independent prediction model. The other one is a cross validation scheme named Bagging approach introduced by Brieman (1996) to derive weighting factors corresponding to individual models. Individual forecasting models that used in this study are linear regression analysis model, polynomial regression, multivariate adaptive regression splines(MARS), SVM(support vector machine). The concepts are demonstrated through application to observed from water plant at several locations in the South Korea. Keywords: water demand, non-linear model, the ensemble forecasting model, uncertainty. Acknowledgements This subject is supported by Korea Ministry of Environment as "Projects for Developing Eco-Innovation Technologies (GT-11-G-02-001-6)

  1. Seasonal dynamic of water on the surface of Mars during MY27 and M28 apheleon and pre-aphelion seasons based on the OMEGA/Mars-Express data

    Science.gov (United States)

    Evdokimova, Nadezda; Kuzmin, Ruslan; Rodin, Alexander V.; Fedorova, Anna; Korablev, Oleg; Bibring, Jean-Pierre

    OMEGA is a mapping spectrometer of the visible and near-infrared ranges. The instrument began its scientific phase on Mars orbit since January 2005 and it is till providing data. The instrument has 3 spectral ranges and we take into account two of them: 0.3-1 and 1-2.5 µm. In this study we focus on changes in the surface composition and structures concerned with global water redistribution during martian year - ices, water vapour, frost, as well as rocks and soils, which possess bound and adsorbed water. We have compared two aphelion seasons, the MY41 and M42 aphelion campaigns, that resulted in global mapping of Mars. Data treatment procedure involved atmospheric corrections, including correction of minor instrumental effects such as pixel-to-pixel nonlinearity and digital noise, and elimination of CO2 and water vapor absorption, based on the European Mars Climate Model,. For mapping of water ice, frosts and water bearing minerals we use features in the 1-2.5 µm spectral range. Spectral imaging data have been treated to retrieve maps of spectral indices related to surface water ice, based on 1.03, 1.2 and 1.5 bands, with the relationships between three H2 O ice features implying the estimate of ice grain size. We used model for BRF calculation (Mishchenko et al,1999) to infer possible water ice grain size variations. So, we studied the evolution of icy polar cap during spring and summer for 2 years. Bound water has been estimated based on the 1.93 feature. The zonal distribution of water ice and bound water around the North pole, frost microphysical structure and its seasonal variations suggest the strong contribution of stationary and quasistationary planetary atmospheric waves residing in the circumpolar vortex, to the water cycle during the aphelion season. Also we analyzed the latitudinal global redistribution of bound water. The results are consistent with simulations of the Mars water cycle we carried out with help of the GFDL General Circulation model

  2. Characterisation of mainstream and passive vapours emitted by selected electronic cigarettes.

    Science.gov (United States)

    Geiss, Otmar; Bianchi, Ivana; Barahona, Francisco; Barrero-Moreno, Josefa

    2015-01-01

    Electronic cigarettes have achieved growing popularity since their introduction onto the European market. They are promoted by manufacturers as healthier alternatives to tobacco cigarettes, however debate among scientists and public health experts about their possible impact on health and indoor air quality means further research into the product is required to ensure decisions of policymakers, health care providers and consumers are based on sound science. This study investigated and characterised the impact of 'vaping' (using electronic cigarettes) on indoor environments under controlled conditions using a 30m(3) emission chamber. The study determined the composition of e-cigarette mainstream vapour in terms of propylene glycol, glycerol, carbonyls and nicotine emissions using a smoking machine with adapted smoking parameters. Two different base recipes for refill liquids, with three different amounts of nicotine each, were tested using two models of e-cigarettes. Refill liquids were analysed on their content of propylene glycol, glycerol, nicotine and qualitatively on their principal flavourings. Possible health effects of e-cigarette use are not discussed in this work. Electronic cigarettes tested in this study proved to be sources for propylene glycol, glycerol, nicotine, carbonyls and aerosol particulates. The extent of exposure differs significantly for active and passive 'vapers' (users of electronic cigarettes). Extrapolating from the average amounts of propylene glycol and glycerol condensed on the smoking machine filter pad to the resulting lung-concentration, estimated lung concentrations of 160 and 220mgm(-3) for propylene glycol and glycerol were obtained, respectively. Vaping refill liquids with nicotine concentrations of 9mgmL(-1) led to vapour condensate nicotine amounts comparable to those of low-nicotine regular cigarettes (0.15-0.2mg). In chamber studies, peak concentrations of 2200μgm(-3) for propylene glycol, 136μgm(-3) for glycerol and 0.6

  3. Evaluating Water Demand Using Agent-Based Modeling

    Science.gov (United States)

    Lowry, T. S.

    2004-12-01

    The supply and demand of water resources are functions of complex, inter-related systems including hydrology, climate, demographics, economics, and policy. To assess the safety and sustainability of water resources, planners often rely on complex numerical models that relate some or all of these systems using mathematical abstractions. The accuracy of these models relies on how well the abstractions capture the true nature of the systems interactions. Typically, these abstractions are based on analyses of observations and/or experiments that account only for the statistical mean behavior of each system. This limits the approach in two important ways: 1) It cannot capture cross-system disruptive events, such as major drought, significant policy change, or terrorist attack, and 2) it cannot resolve sub-system level responses. To overcome these limitations, we are developing an agent-based water resources model that includes the systems of hydrology, climate, demographics, economics, and policy, to examine water demand during normal and extraordinary conditions. Agent-based modeling (ABM) develops functional relationships between systems by modeling the interaction between individuals (agents), who behave according to a probabilistic set of rules. ABM is a "bottom-up" modeling approach in that it defines macro-system behavior by modeling the micro-behavior of individual agents. While each agent's behavior is often simple and predictable, the aggregate behavior of all agents in each system can be complex, unpredictable, and different than behaviors observed in mean-behavior models. Furthermore, the ABM approach creates a virtual laboratory where the effects of policy changes and/or extraordinary events can be simulated. Our model, which is based on the demographics and hydrology of the Middle Rio Grande Basin in the state of New Mexico, includes agent groups of residential, agricultural, and industrial users. Each agent within each group determines its water usage

  4. Evaluation of Crop-Water Consumption Simulation to Support Agricultural Water Resource Management using Satellite-based Water Cycle Observations

    Science.gov (United States)

    Gupta, M.; Bolten, J. D.; Lakshmi, V.

    2016-12-01

    Water scarcity is one of the main factors limiting agricultural development. Numerical models integrated with remote sensing datasets are increasingly being used operationally as inputs for crop water balance models and agricultural forecasting due to increasing availability of high temporal and spatial resolution datasets. However, the model accuracy in simulating soil water content is affected by the accuracy of the soil hydraulic parameters used in the model, which are used in the governing equations. However, soil databases are known to have a high uncertainty across scales. Also, for agricultural sites, the in-situ measurements of soil moisture are currently limited to discrete measurements at specific locations, and such point-based measurements do not represent the spatial distribution at a larger scale accurately, as soil moisture is highly variable both spatially and temporally. The present study utilizes effective soil hydraulic parameters obtained using a 1-km downscaled microwave remote sensing soil moisture product based on the NASA Advanced Microwave Scanning Radiometer (AMSR-E) using the genetic algorithm inverse method within the Catchment Land Surface Model (CLSM). Secondly, to provide realistic irrigation estimates for agricultural sites, an irrigation scheme within the land surface model is triggered when the root-zone soil moisture deficit reaches the threshold, 50% with respect to the maximum available water capacity obtained from the effective soil hydraulic parameters. An additional important criterion utilized is the estimation of crop water consumption based on dynamic root growth and uptake in root zone layer. Model performance is evaluated using MODIS land surface temperature (LST) product. The soil moisture estimates for the root zone are also validated with the in situ field data, for three sites (2- irrigated and 1- rainfed) located at the University of Nebraska Agricultural Research and Development Center near Mead, NE and monitored

  5. Performance of Water-Based Liquid Scintillator: An Independent Analysis

    Directory of Open Access Journals (Sweden)

    D. Beznosko

    2014-01-01

    Full Text Available The water-based liquid scintillator (WbLS is a new material currently under development. It is based on the idea of dissolving the organic scintillator in water using special surfactants. This material strives to achieve the novel detection techniques by combining the Cerenkov rings and scintillation light, as well as the total cost reduction compared to pure liquid scintillator (LS. The independent light yield measurement analysis for the light yield measurements using three different proton beam energies (210 MeV, 475 MeV, and 2000 MeV for water, two different WbLS formulations (0.4% and 0.99%, and pure LS conducted at Brookhaven National Laboratory, USA, is presented. The results show that a goal of ~100 optical photons/MeV, indicated by the simulation to be an optimal light yield for observing both the Cerenkov ring and the scintillation light from the proton decay in a large water detector, has been achieved.

  6. Solar-Based Fuzzy Intelligent Water Sprinkle System

    Directory of Open Access Journals (Sweden)

    Riza Muhida

    2012-03-01

    Full Text Available A solar-based intelligent water sprinkler system project that has been developed to ensure the effectiveness in watering the plant is improved by making the system automated. The control system consists of an electrical capacitance soil moisture sensor installed into the ground which is interfaced to a controller unit of Motorola 68HC11 Handy board microcontroller. The microcontroller was programmed based on the decision rules made using fuzzy logic approach on when to water the lawn. The whole system is powered up by the solar energy which is then interfaced to a particular type of irrigation timer for plant fertilizing schedule and rain detector through a simple design of rain dual-collector tipping bucket. The controller unit automatically disrupted voltage signals sent to the control valves whenever irrigation was not needed. Using this system we combined the logic implementation in the area of irrigation and weather sensing equipment, and more efficient water delivery can be made possible. 

  7. Comparison of the cytotoxic potential of cigarette smoke and electronic cigarette vapour extract on cultured myocardial cells.

    Science.gov (United States)

    Farsalinos, Konstantinos E; Romagna, Giorgio; Allifranchini, Elena; Ripamonti, Emiliano; Bocchietto, Elena; Todeschi, Stefano; Tsiapras, Dimitris; Kyrzopoulos, Stamatis; Voudris, Vassilis

    2013-10-16

    Electronic cigarettes (ECs) have been marketed as an alternative-to-smoking habit. Besides chemical studies of the content of EC liquids or vapour, little research has been conducted on their in vitro effects. Smoking is an important risk factor for cardiovascular disease and cigarette smoke (CS) has well-established cytotoxic effects on myocardial cells. The purpose of this study was to evaluate the cytotoxic potential of the vapour of 20 EC liquid samples and a "base" liquid sample (50% glycerol and 50% propylene glycol, with no nicotine or flavourings) on cultured myocardial cells. Included were 4 samples produced by using cured tobacco leaves in order to extract the tobacco flavour. Cytotoxicity was tested according to the ISO 10993-5 standard. By activating an EC device at 3.7 volts (6.2 watt