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1

Water vapor permeabilities through polymers: diffusivities from experiments and simulations  

NASA Astrophysics Data System (ADS)

This study experimentally determines water vapor permeabilities, which are subsequently correlated with the diffusivities obtained from simulations. Molecular dynamics (MD) simulations were used for determining the diffusion of water vapor in various polymeric systems such as polyethylene, polypropylene, poly (vinyl alcohol), poly (vinyl acetate), poly (vinyl butyral), poly (vinylidene chloride), poly (vinyl chloride) and poly (methyl methacrylate). Cavity ring down spectroscopy (CRDS) based methodology has been used to determine the water vapor transmission rates. These values were then used to calculate the diffusion coefficients for water vapor through these polymers. A comparative analysis is provided for diffusivities calculated from CRDS and MD based results by correlating the free volumes.

Seethamraju, Sindhu; Chandrashekarapura Ramamurthy, Praveen; Madras, Giridhar

2014-09-01

2

Observation system simulation experiments using water vapor isotope information  

NASA Astrophysics Data System (ADS)

of water vapor isotopes (?18O and ?D) have dramatically increased in recent years with the availability of new spectroscopic technology. To utilize these data more efficiently, this study first developed a new data assimilation system using a local transform ensemble Kalman filter (LETKF) and the Isotope-incorporated Global Spectral Model (IsoGSM). An observation system simulation experiment (OSSE) was then conducted. The OSSE used a synthetic data set of vapor isotope measurements, mimicking Tropospheric Emission Spectrometer (TES)-retrieved ?D from the mid-troposphere, SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY)-retrieved ?D from the water vapor column, and the virtual Global Network of Isotopes in Precipitation (GNIP)-like surface vapor isotope (both ?D and ?18O) monitoring network. For TES and SCIAMACHY, we assumed a similar spatiotemporal coverage as that of the real data sets. For the virtual GNIP-like network, we assumed ~200 sites worldwide and 6-hourly measurements. An OSSE with 20 ensemble members was then conducted for January 2006. The results showed a significant improvement in not only the vapor isotopic field but also meteorological fields, such as wind speed, temperature, surface pressure, and humidity, when compared with a test with no observations. For surface air temperature, the global root mean square error has dropped by 10%, with 40-60% of the decrease occurring in the east-southeast Asia where the concentration of observations is relatively higher. When there is a conventional radiosonde network, the improvement gained by adding isotopic measurements was small but positive for all variables.

Yoshimura, Kei; Miyoshi, Takemasa; Kanamitsu, Masao

2014-07-01

3

A Simple Experiment for Determining Vapor Pressure and Enthalpy of Vaporization of Water.  

ERIC Educational Resources Information Center

Laboratory procedures, calculations, and sample results are described for a freshman chemistry experiment in which the Clausius-Clapeyron equation is introduced as a means of describing the variation of vapor pressure with temperature and for determining enthalpy of vaporization. (Author/SK)

Levinson, Gerald S.

1982-01-01

4

Water Vapor Imagery: Water Vapor Imagery Basics  

NSDL National Science Digital Library

This self-paced, interactive tutorial enables learners to discover practical uses for water vapor imagery from weather satellites. The module introduces the concept and function of the water vapor channel of satellite imagery, and teaches how to interpret and apply data obtained from the water vapor channel. At the end of the tutorial, links are provided to real world data collected by NASA satellites where learners can apply the skills they have acquired. This resource is part of the tutorial series, Satellite Observations in Science Education, and is the first of three modules in the tutorial, Water Vapor Imagery. (Note: requires Java plug-in)

5

17Oexcess in evaporated desert waters and vapor from evaporation experiments  

NASA Astrophysics Data System (ADS)

Oxygen and hydrogen isotopes are classical proxies for the investigation of climatic effects in hydrological processes. The combination of the isotopic ratios 17O/16O and 18O/16O in water allowed the determination of mass dependent processes and enabled differentiation between equilibrium and kinetic fractionation (Barkan and Luz, 2007). In analogy to d-excess, deviation in ?17O from the global average trend of meteoric water is defined as: 17Oexcess = ?'17O - 0.528 × ?'18O 17Oexcess depends on the impact of diffusive evaporation into air and thus reflects relative humidity conditions. The isotope ratios of water ?17O and ?18O were determined by isotope ratio gas mass spectrometry in dual inlet mode on a ThermoFinnigan MAT 253. The oxygen was extracted by water fluorination with CoF3. Our average measurement precision for ?17O is ×0.03 ‰, for ?18O ×0.05 ‰ and for 17Oexcess approximately ×7 per meg (1?). We compared 17Oexcess in natural waters from the highly arid deserts of Sistan (East Iran) and Atacama (Chile) with data obtained from evaporation experiments. In these experiments, water was evaporated into a stream of dry nitrogen and vapor collected cryogenically. The data show a systematic depletion of 17Oexcess in water with increasing degree of evaporation in the residual water body. Most negative 17Oexcess were determined for samples from ponds (Sistan) and salars (Atacama). These strongly evaporated samples indicate an evaporation development, following a fractionation trend (?) of approximately 0.523. The evaporation experiment shows a ? of 0.525 and is in agreement with water data from an experiment by Barkan and Luz (2007). The difference between natural and experimental evaporation suggests either different evaporation kinetics in the natural environment, variable proportion of kinetic and equilibrium fractionation, or additional diffusive processes during ground water seepage. References: Barkan, E. and Luz, L. (2007). Diffusivity fractionations of H216O/H217O and H216O/H218O in air and their implications for isotope hydrology. Rapid Commun. Mass Spectrom., Vol. 21, pp. 2999-3005.

Surma, J.; Assonov, S.; Staubwasser, M.

2013-12-01

6

Role of water vapor and convection during the Central Equatorial Pacific Experiment (CEPEX) from observations and model simulations.  

National Technical Information Service (NTIS)

Observed data from field measurements taken during the Central Equatorial Pacific EXperiment (CEPEX) conducted from March 7 to April 5, 1993 are used to study the link between water vapor, convection and SST in comparison with results from a general circu...

U. Lohmann, E. Roeckner, W. D. Collins, A. J. Heymsfield, G. McFarquhar

1995-01-01

7

LASE validation experiment: preliminary processing of relative humidity from LASE derived water vapor in the middle to upper troposphere  

NASA Technical Reports Server (NTRS)

Lidar Atmospheric Sensing Experiment (LASE) is the first fully engineered, autonomous airborne DIAL (Differentials Absorption Lidar) system to measure water vapor, aerosols, and clouds throughout the troposphere. This system uses a double-pulsed Ti:sapphire laser, which is pumped by a frequency-doubled flashlamp-pumped Nd: YAG laser, to transmit light in the 815 mn absorption band of water vapor. LASE operates by locking to a strong water vapor line and electronically tuning to any spectral position on the absorption line to choose the suitable absorption cross-section for optimum measurements over a range of concentrations in the atmosphere. During the LASE Validation Experiment, which was conducted over Wallops Island during September, 1995, LASE operated on either the strong water line for measurements in middle to upper troposphere, or on the weak water line for measurements made in the middle to lower troposphere including the boundary layer. Comparisons with water vapor measurements made by airborne dew point and frost point hygrometers, NASA/GSFC (Goddard Space Flight Center) Raman Lidar, and radiosondes showed the LASE water vapor mixing ratio measurements to have an accuracy of better than 6% or 0.01 g/kg, whichever is larger, throughout the troposphere. In addition to measuring water vapor mixing ratio profiles, LASE simultaneously measures aerosol backscattering profiles at the off-line wavelength near 815 nm from which atmospheric scattering ratio (ASR) profiles are calculated. ASR is defined as the ratio of total (aerosol + molecular) atmospheric scattering to molecular scattering. Assuming a region with very low aerosol loading can be identified, such as that typically found just below the tropopause, then the ASR can be determined. The ASR profiles are calculated by normalizing the scattering in the region containing enhanced aerosols to the expected scattering by the "clean" atmosphere at that altitude. Images of the total ASR clearly depict cloud regions, including multiple cloud layers, thin upper level cirrus, etc., throughout the troposphere. New data products that are being derived from the LASE aerosol and water measurements include: 1) aerosol extinction coefficient, 2) aerosol optical thickness, 3) precipitable water vapor, and 4) relative humidity (RH). These products can be compared with airborne in-situ, and ground and satellite remote sensing measurements,. This paper presents a preliminary examination of RH profiles in the middle to upper troposphere that are generated from LASE measured water vapor mixing ratio profiles coupled with rawinsonde profiles of temperature and pressure.

Brackett, Vincent G.; Ismail, Syed; Browell, Edward V.; Kooi, Susan A.; Clayton, Marian B.; Ferrare, Richard A.; Minnis, Patrick; Getzewich, Brian J.; Staszel, Jennifer

1998-01-01

8

Intercomparison of stratospheric water vapor observed by satellite experiments - Stratospheric Aerosol and Gas Experiment II versus Limb Infrared Monitor of the Stratosphere and Atmospheric Trace Molecule Spectroscopy  

NASA Technical Reports Server (NTRS)

A comparison is made of the stratospheric water vapor measurements made by the satellite sensors of the Stratospheric Aerosol and Gas Experiment II (SAGE II), the Nimbus-7 LIMS, and the Spacelab 3 Atmospheric Trace Molecule Spectroscopy (ATMOS) experiment. It was found that, despite differences in the measurement techniques, sampling bias, and observational periods, the three experiments have disclosed a generally consistent pattern of stratospheric water vapor distribution. The only significant difference occurs at high southern altitudes in May below 18 km, where LIMS measurements were 2-3 ppmv greater than those of SAGE II and ATMOS.

Chiou, E. W.; Mccormick, M. P.; Mcmaster, L. R.; Chu, W. P.; Larsen, J. C.; Rind, D.; Oltmans, S.

1993-01-01

9

Vapor Compression Distillation Flight Experiment  

NASA Technical Reports Server (NTRS)

One of the major requirements associated with operating the International Space Station is the transportation -- space shuttle and Russian Progress spacecraft launches - necessary to re-supply station crews with food and water. The Vapor Compression Distillation (VCD) Flight Experiment, managed by NASA's Marshall Space Flight Center in Huntsville, Ala., is a full-scale demonstration of technology being developed to recycle crewmember urine and wastewater aboard the International Space Station and thereby reduce the amount of water that must be re-supplied. Based on results of the VCD Flight Experiment, an operational urine processor will be installed in Node 3 of the space station in 2005.

Hutchens, Cindy F.

2002-01-01

10

Meteorological context for fall experiments including distributions of water vapor, ozone, and carbon monoxide  

NASA Technical Reports Server (NTRS)

Meteorological contexts for the NASA GTE/CITE 1 fall 1983 flight series are presented and discussed. The large-scale wind, cold cloud, and moisture patterns are illustrated by composite diagrams based on the National Oceanic and Atmospheric Administration 700-, 500-, and 250-mbar analyses and the GOES-West broadband and 6.7-micron (water vapor) infrared photographs. Detailed flight path diagrams are included for seven maritime flights and one continental flight in the free troposphere and boundary layer. For three flights from Hickam Field, in Honolulu, HI, to the Intertropical Convergence Zone, vertical profiles of temperature, dew/frost point departures, wind velocity, and ozone, and carbon monoxide mixing ratios are also presented and discussed. Excellent agreement is demonstrated between the in situ and remote measurements. In particular, the predictive and diagnostic value of the 6.7-micron water vapor photographs is demonstrated.

Danielsen, Edwin F.; Gregory, Gerald L.; Sachse, Glen W.; Hill, G. F.; Gaines, Steven E.

1987-01-01

11

Water vapor lidar  

NASA Technical Reports Server (NTRS)

The feasibility was studied of measuring atmospheric water vapor by means of a tunable lidar operated from the space shuttle. The specific method evaluated was differential absorption, a two-color method in which the atmospheric path of interest is traversed by two laser pulses. Results are reported.

Ellingson, R.; Mcilrath, T.; Schwemmer, G.; Wilkerson, T. D.

1976-01-01

12

Water Vapor: Distribution and Trends  

Microsoft Academic Search

Water in the gaseous phase, water vapor, is the most significant atmospheric trace constituent vis-` a-vis climate, weather, hydro- logy, and atmospheric chemistry. Water vapor is the most abundant atmospheric greenhouse gas, and without it the planet's sur- face temperature would be well below freezing. Phase changes involving water vapor - the condensation and evaporation pro- cesses - involve exchanges

Dian J Seidel

2002-01-01

13

Water vaporization on Ceres  

NASA Technical Reports Server (NTRS)

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

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

1992-01-01

14

Quantification of the water vapor greenhouse effect: setup and first results of the Zugspitze radiative closure experiment  

NASA Astrophysics Data System (ADS)

Uncertainties in the knowledge of atmospheric radiative processes are among the main limiting factors for the accuracy of current climate models. Being the primary greenhouse gas in the Earth's atmosphere, water vapor is of crucial importance in atmospheric radiative transfer. However, water vapor absorption processes, especially the contribution attributed to the water vapor continuum, are currently not sufficiently well quantified. The aim of this study is therefore to obtain a more exact characterization of the water vapor radiative processes throughout the IR by means of a so-called radiative closure study at the Zugspitze/Schneefernerhaus observatory and thereby validate the radiative transfer codes used in current climate models. For that purpose, spectral radiance is measured at the Zugspitze summit observatory using an AERI-ER thermal emission radiometer (covering the far- and mid-infrared) and a solar absorption FTIR spectrometer (covering the near-infrared), respectively. These measurements are then compared to synthetic radiance spectra computed by means of the Line-By-Line Radiative Transfer Model (LBLRTM, Clough et al., 2005), a high resolution model widely used in the atmospheric science community. This line-by-line code provides the foundation of RRTM, a rapid radiation code (Mlawer et al., 1997) used in various weather forecast models or general circulation models like ECHAM. To be able to quantify errors in the description of water vapor radiative processes from spectral residuals, i.e. difference spectra between measured and calculated radiance, the atmospheric state used as an input to LBLRTM has to be constrained precisely. This input comprises water vapor columns, water vapor profiles, and temperature profiles measured by an LHATPRO microwave radiometer along with total column information on further trace gases (e.g. CO2 and O3) measured by the solar FTIR. We will present the setup of the Zugspitze radiative closure experiment. Due to its high-altitude location and the available permanent instrumentation, the Zugspitze observatory meets the necessary requirements to determine highly accurate water vapor continuum absorption parameters in the far- and mid-infrared spectral range from a more extensive set of closure measurements compared to previous campaign-based studies. Furthermore, we will present a novel radiometric calibration strategy for the solar FTIR spectral radiance measurements based on a combination of the Langley method and measurements of a high-temperature blackbody source that allows for the determination of continuum absorption parameters in the near-infrared spectral region, where previously no precise measurements under atmospheric conditions were available. This improved quantification of water vapor continuum absorption parameters allows us to further validate the current standard continuum model MT_CKD (Mlawer et al., 2012). Acknowledgements: Funding by KIT/IMK-IFU, the State Government of Bavaria as well as by the Deutsche Bundesstiftung Umwelt (DBU) is gratefully acknowledged. References: Clough, S. A., Shephard, M. W., Mlawer, E. J., Delamere, J. S., Iacono, M. J., Cady-Pereira, K., Boukabara, S., and Brown, P. D: Atmospheric radiative transfer modeling: a summary of the AER codes, Short Communication, J. Quant. Spectrosc. Radiat. Transfer, 91, 233-244, 2005. Mlawer, E. J., Taubman, J., Brown, P.D., Iacono, M.J, and Clough, S.A.: RRTM, a validated correlated-k model for the longwave. J. Geophys. Res., 102, 16,663-16,682, 1997. Mlawer, E. J., Payne V. H., Moncet, J., Delamere, J. S., Alvarado, M. J. and Tobin, D.C.: Development and recent evaluation of the MT_CKD model of continuum absorption, Phil. Trans. R. Soc. A, 370, 2520-2556, 2012.

Reichert, Andreas; Sussmann, Ralf; Rettinger, Markus

2014-05-01

15

Implications of the stratospheric water vapor distribution as determined from the Nimbus 7 LIMS experiment. [Limb Infrared Monitor of Stratosphere  

NASA Technical Reports Server (NTRS)

The LIMS experiment on Nimbus 7 has provided new results on the stratospheric water vapor distribution. The data show (1) a latitudinal gradient with mixing ratios that increase by a factor of 2 from equator to + or - 60 degrees at 50 mb, (2) most of the time there is a fairly uniform mixing ratio of 5 ppmv at high latitudes, but more variation exists during winter, (3) a well-developed hygropause at low to midlatitudes of the lower stratosphere, (4) a source region of water vapor in the upper stratospehere to lower mesosphere that is consistent with methane oxidation chemistry, at least within the uncertainties of the data, (5) an apparent zonal mean H2O distribution that is consistent with the circulation proposed by Brewer in 1949, and (6) a zonal mean distribution in the lower stratosphere that is consistent with the idea of quasi-isentropic transport by eddies in the meridional direction. Limits to the use of the data in the refinement of our understanding of the stratospheric water vapor budget are noted.

Remsberg, E. E.; Russell, J. M., III; Gordley, L. L.; Gille, J. C.; Bailey, P. L.

1984-01-01

16

Water Vapor Circulation on Earth  

NSDL National Science Digital Library

Water vapor plays an important role in the water cycle and in the distribution of heat around the planet. By observing the movement of water vapor, scientists can study global wind patterns and the development of cyclonic storms. This simulation from the National Center for Atmospheric Research shows the circulation of water vapor around the Earth over the course of a year. The segment is four minutes fifty-two seconds in length.

17

Tropospheric water vapor measurements over the North Atlantic during the Subsonic Assessment Ozone and Nitrogen Oxide Experiment (SONEX)  

NASA Astrophysics Data System (ADS)

Fast-response tunable diode laser measurements of water vapor were made over the North Atlantic during the Subsonic Assessment Ozone and Nitrogen Oxide Experiment (SONEX) conducted in the fall of 1997. Resulting water vapor mixing ratios, in conjunction with air temperature and pressure measurements obtained by the DC-8's Data Acquisition and Distribution System (DADS), were used to calculate the prevalence of ice-saturated conditions (relative humidity with respect to ice >100% or frost saturation) in the upper troposphere over the SONEX sampling region. Additionally, Appleman theory was applied to the data to determine the subset of ice-saturated regions which would support formation of contrails. Results suggest that studies to determine the potential climate or radiative impact of contrails and aviation-induced cirrus clouds should not only consider the climatology of frost-saturated regions, but should also address whether ambient conditions can support contrail formation within these regions. A separate discussion within the paper describes an in-flight intercomparison between the SONEX diode laser hygrometer and the Pollution From Aircraft Emissions in the North Atlantic Flight Corridor (POLINAT 2) cryogenic hygrometer and shows that the instruments perform to within their stated accuracies (˜10%) over a range of mixing ratios and altitudes.

Vay, S. A.; Anderson, B. E.; Jensen, E. J.; Sachse, G. W.; Ovarlez, J.; Gregory, G. L.; Nolf, S. R.; Podolske, J. R.; Slate, T. A.; Sorenson, C. E.

2000-02-01

18

A Physical Experiment to determine the Impact of Atmospheric Condensation of Water Vapor on Surface Air Movement  

NASA Astrophysics Data System (ADS)

A physical experiment, in which atmospheric air is enclosed in two interconnecting 4.8-metre high insulated PVC columns, consistently gives results showing that the condensation of water vapor, precipitated by means of refrigeration coils, gives rise to detectable air movements, with air speeds of up to 0.1 m/s. Once the compressor, sited well away from the two columns, is shut down, heavy drops of precipitated water are obtained which funnel into a flask for collection and measurement. The results in kg.m-2 (mm) from the 20 m3 volume of enclosed air accord well (>90%) with the physical calculations based on water vapor as an ideal gas. Air flow, resulting from the highly localized condensation, is measured through the movement of light-weight gauzes and an anemometer. It has a circulation time of some two minutes, such that both columns show cooling and a significant reduction in specific humidity from 0.01 to 0.005 (kg water vapor to kg dry air, r) with a drop in relative humidity of up to 40 per cent. Air flow is minimal during the control, non-refrigeration period of the experiment but becomes substantial within a minute of the compressor being switched on. The negative partial pressure change peaks at as much as 0.4 Pa/s during the first 30 minutes but reduces to approx. 0.08 Pa/s during the latter part of the 110 minute- long experiment. Airflow displays an inverse relationship to the partial pressure change, initially rising rapidly and then reducing before returning to zero once refrigeration has been switched off. Inverse correlations of up to 0.8 or higher between the partial pressure reduction and the airflow are obtained routinely. Semi-aquatic vegetation from the nearby marshland enhances precipitation, suggesting that evapotranspiration adds significantly to humidity. Without vegetation the condensation rate is 0.06 to 0.07 millimol.m-3.s-1 on average compared with 0.11 when vegetation is present. Cooling, by some 2°C, combined with a reduction in water vapor, by 6 grams/m3during the course of the experiment, leads to differential increases in air density. The latent heat released during condensation tends to warm the air in the immediate vicinity of the coolant coils and as such would tend to counter the air clockwise air-circulation, the assumption being that the highly localized partial pressure reduction on condensation is the overriding force. The experimental data accords well with data from Costa Rica, where, for the past three years, daily meteorological data have been collected from two OTS sites, namely La Selva and Palo Verde, the former in particular displaying relatively high rates of evapotranspiration. Statistically high correlations are found between the calculated evaporative/condensation force fE, and corresponding surface wind movements. Those findings, combined with the experimental data, suggest that a high rate of condensation and the consequent partial pressure reduction at the scale of the lower trophosphere leads to horizontal surface airflows of the order of 1 m.s-1.

Bunyard, P. P.; Nechev, P.

2013-12-01

19

Advanced Raman water vapor lidar  

NASA Technical Reports Server (NTRS)

Water vapor and aerosols are important atmospheric constituents. Knowledge of the structure of water vapor is important in understanding convective development, atmospheric stability, the interaction of the atmosphere with the surface, and energy feedback mechanisms and how they relate to global warming calculations. The Raman Lidar group at the NASA Goddard Space Flight Center (GSFC) developed an advanced Raman Lidar for use in measuring water vapor and aerosols in the earth's atmosphere. Drawing on the experience gained through the development and use of our previous Nd:YAG based system, we have developed a completely new lidar system which uses a XeF excimer laser and a large scanning mirror. The additional power of the excimer and the considerably improved optical throughput of the system have resulted in approximately a factor of 25 improvement in system performance for nighttime measurements. Every component of the current system has new design concepts incorporated. The lidar system consists of two mobile trailers; the first (13m x 2.4m) houses the lidar instrument, the other (9.75m x 2.4m) is for system control, realtime data display, and analysis. The laser transmitter is a Lambda Physik LPX 240 iCC operating at 400 Hz with a XeF gas mixture (351 nm). The telescope is a .75m horizontally mounted Dall-Kirkham system which is bore sited with a .8m x 1.1m elliptical flat which has a full 180 degree scan capability - horizon to horizon within a plane perpendicular to the long axis of the trailer. The telescope and scan mirror assembly are mounted on a 3.65m x .9m optical table which deploys out the rear of the trailer through the use of a motor driven slide rail system. The Raman returns from water vapor (403 nm), nitrogen (383 nm) and oxygen (372 nm) are measured in addition to the direct Rayleigh/Mie backscatter (351). The signal from each of these is split at about a 5/95 ratio between two photomultiplier detectors. The 5 percent detector is used for measurements below about 4.0 km, while the 95 percent detector provides the information above this level.

Whiteman, David N.; Melfi, S. Harvey; Ferrare, Richard A.; Evans, Keith A.; Ramos-Izquierdo, Luis; Staley, O. Glenn; Disilvestre, Raymond W.; Gorin, Inna; Kirks, Kenneth R.; Mamakos, William A.

1992-01-01

20

Validation of measurements of water vapor from the Halogen Occultation Experiment (HALOE)  

Microsoft Academic Search

The Halogen Occultation Experiment (HALOE) experiment is a solar occultation limb sounder which operates between 2.45 and 10.0 mum to measure the composition of the mesosphere, stratosphere, and upper troposphere. It flies onboard the Upper Atmosphere Research Satellite (UARS) which was launched in September 1991. Measurements are made of the transmittance of the atmosphere in a number of spectral channels

J. E. Harries; J. M. Russell; A. F. Tuck; L. L. Gordley; P. Purcell; K. Stone; R. M. Bevilacqua; M. Gunson; G. Nedoluha; W. A. Traub

1996-01-01

21

Evaluation of Terms in the Water Vapor Budget Using Airborne Dial and In Situ Measurements from the Southern Great Plans 1997 Experiment  

NASA Technical Reports Server (NTRS)

The Southern Great Plains (SGP97) field experiment was conducted in Oklahoma during June and July 1997 primarily to validate soil moisture retrieval algorithms using microwave radiometer measurements from aircraft as well as in situ surface measurements. One important objective of the SGP97 experiment plan was to examine the effect of soil moisture on the evolution of the atmospheric boundary layer (ABL) and clouds over the Southern Great Plains during the warm season. To support boundary layer studies during SGP97. the NASA Langley Research Center's Lidar Atmospheric Sensing Experiment (LASE) was flown on a NASA-P3 aircraft in conjunction with the Electronically Scanned Thinned Array Radiometer (ESTAR). The LASE instrument is an airborne, downward-looking differential absorption lidar (DIAL) system capable of measuring water vapor concentration as well as aerosol backscatter with high horizontal and vertical resolution in the ABL. Here, we will demonstrate how the LASE data can be used to determine water vapor statistics and most of the water vapor budget terms in the ABL. This information can then be related to spatial variations in soil moisture and the surface energy budget. The extensive surface and aircraft in situ measurements conducted during SGP97 provide information on the ABL that cannot be retrieved from the LASE data alone and also offer an excellent opportunity to validate the remote water vapor budget measurements with LASE.

Senff, Christoph J.; Davis, Kenneth J.; Lenschow, Donald H.; Browell, Edward V.; Ismail, Syed

1998-01-01

22

Forward Model Studies of Water Vapor Using Scanning Microwave Radiometers, Global Positioning System, and Radiosondes during the Cloudiness Intercomparison Experiment  

SciTech Connect

Brightness temperatures computed from five absorption models and radiosonde observations were analyzed by comparing them with measurements from three microwave radiometers at 23.8 and 31.4 GHz. Data were obtained during the Cloudiness Inter-Comparison experiment at the U.S. Department of Energy's Atmospheric Radiation Measurement Program's (ARM) site in North-Central Oklahoma in 2003. The radiometers were calibrated using two procedures, the so-called instantaneous ?tipcal? method and an automatic self-calibration algorithm. Measurements from the radiometers were in agreement, with less than a 0.4-K difference during clear skies, when the instantaneous method was applied. Brightness temperatures from the radiometer and the radiosonde showed an agreement of less than 0.55 K when the most recent absorption models were considered. Precipitable water vapor (PWV) computed from the radiometers were also compared to the PWV derived from a Global Positioning System station that operates at the ARM site. The instruments agree to within 0.1 cm in PWV retrieval.

Mattioli, Vinia; Westwater, Ed R.; Gutman, S.; Morris, Victor R.

2005-05-01

23

Validation of v1.022 mesospheric water vapor observed by the Solar Occultation for Ice Experiment instrument on the Aeronomy of Ice in the Mesosphere satellite  

Microsoft Academic Search

Water vapor measured by the Solar Occultation for Ice Experiment (SOFIE) instrument on the Aeronomy of Ice in the Mesosphere satellite has been validated in the vertical range 45–95 km. Precision estimates for SOFIE v1.022 H2O are ?0.2%–2.5% up to 80 km and degrade to ?20% at ?90 km. The SOFIE total systematic error from the retrieval analysis remains at

Pingping Rong; James M. Russell III; Larry L. Gordley; Mark E. Hervig; Lance Deaver; Peter F. Bernath; Kaley A. Walker

2010-01-01

24

Water vapor in protoplanetary disks  

NASA Astrophysics Data System (ADS)

This thesis is devoted to a study of the conditions and evolution of the planet formation region in young circumstellar disks, by means of spectroscopic observations of molecular gas emission. The main focus of this work is the infrared spectrum of water (H2O), which provides thousands of emission lines tracing the warm and dense gas inward of the water snow line in disks. The analysis includes also emission from some organic molecules that trace the carbon chemistry, C2H2, HCN, and CO2, as well as emission from OH that is connected to the formation and destruction of the water molecule. Two are the main directions explored in this work, for which we used spectra from the Spitzer Space Telescope (IRS) and the Very Large Telescope (VISIR and X-shooter). The first is to investigate how variable accretion phenomena occurring during the T Tauri phase affect the molecular environments in the planet formation region of disks. By monitoring T Tauri stars in different phases of accretion, we found that outbursts can remarkably affect their mid-infrared molecular emission. We propose a scenario where accretion flares trigger a recession of the water snow line, increasing water emission from the disk, when the accretion luminosity keeps higher over long enough timescales for the thermal structure of the disk to change (at least a few weeks, as observed in the strongly variable EX Lupi). In addition, enhanced UV radiation is found to produce OH from photodissociation of water in the disk. Organic molecules instead disappear during a strong outburst, and we are currently investigating the long-term evolution of these effects. A second direction was taken to tackle another fundamental problem: the origin of water vapor in inner disks. Some models predict that water is produced by evaporation of icy solids migrating inward of the snow line. One way to probe this scenario is by measuring the abundance of water vapor in the inner disk, and compare it to the oxygen abundance available to form water in situ. In this thesis, for the first time, a systematic rotation diagram analysis has been applied to infrared water emission. This analysis established a link between the spread of the rotational scatter and the water abundance in the inner disk, where a large rotational scatter would provide evidence for the migration scenario. Large rotational scatters are indeed tentatively observed in some disks, supporting water vapor enrichment from evaporation of icy migrators. Future higher-resolution observations will provide important answers on the origin of water vapor and its connection to disk evolution and planet formation processes.

Banzatti, Andrea

2013-03-01

25

Remote sensing of water vapor features  

NASA Technical Reports Server (NTRS)

The three major objectives of the project are outlined: (1) to describe atmospheric water vapor features as functions of space and time; (2) to evaluate remotely sensed measurements of water vapor content; and (3) to study relations between fine-scale water vapor fields and convective activity. Data from several remote sensors were used. The studies used the GOES/VAS, HIS, and MAMS instruments have provided a progressively finer scale view of water vapor features.

Fuelberg, Henry E.

1991-01-01

26

TROPOSPHERIC WATER VAPOR, CONVECTION, AND CLIMATE  

E-print Network

with water vapor and changes associated with water vapor in warmer climates. Progress includes new observing consequences of increased specific humidity in a warmer climate. A theory appears to be in place to predict on climate changes driven by other influences. The latent heat of water vapor also accounts for roughly half

Sherwood, Steven

27

WATER VAPOR FEEDBACK AND GLOBAL WARMING1  

Microsoft Academic Search

Abstract Water vapor is the dominant greenhouse gas, the most important gaseous source of infrared opacity in the atmosphere. As the concentrations of other greenhouse gases, particularly carbon dioxide, increase because of human activity, it is centrally important to predict how the water vapor distribution will be affected. To the extent that water vapor concentrations increase in a warmer world,

Isaac M. Held; Brian J. Soden

2000-01-01

28

Internal Water Vapor Photoacoustic Calibration  

NASA Technical Reports Server (NTRS)

Water vapor absorption is ubiquitous in the infrared wavelength range where photoacoustic trace gas detectors operate. This technique allows for discontinuous wavelength tuning by temperature-jumping a laser diode from one range to another within a time span suitable for photoacoustic calibration. The use of an internal calibration eliminates the need for external calibrated reference gases. Commercial applications include an improvement of photoacoustic spectrometers in all fields of use.

Pilgrim, Jeffrey S.

2009-01-01

29

What Good is Raman Water Vapor Lidar?  

NASA Technical Reports Server (NTRS)

Raman lidar has been used to quantify water vapor in the atmosphere for various scientific studies including mesoscale meteorology and satellite validation. Now the international networks of NDACC and GRUAN have interest in using Raman water vapor lidar for detecting trends in atmospheric water vapor concentrations. What are the data needs for addressing these very different measurement challenges. We will review briefly the scientific needs for water vapor accuracy for each of these three applications and attempt to translate that into performance specifications for Raman lidar in an effort to address the question in the title of "What good is Raman water vapor Iidar."

Whitman, David

2011-01-01

30

Venus Balloons using Water Vapor  

NASA Astrophysics Data System (ADS)

We propose an inflatable balloon using water vapor for the lifting gas, which is liquid in the transportation stage before entry into the high temperature atmosphere. The envelope of the balloon has an outer layer for gas barrier (a high-temperature resistant film) and an inner layer for liquid water keeping. In the descent stage using a parachute, water widely held just inside the balloon envelope can be quickly vaporized by a lot of heat flux from the surrounding high-temperature atmosphere owing to the large surface area of the balloon. As neither gas containers nor heat exchangers are necessary, we can construct a simple, lightweight and small size Venus balloon probe system. Tentative floating altitude is 35 km below the thick clouds in the Venusian atmosphere. Selection of balloon shape and material for balloon envelope are discussed in consideration of the Venusian environment such as high-temperature, high-pressure, and sulfuric acid. Balloon deployment and inflation sequence is numerically simulated. In case of the total floating mass of 10 kg at the altitude of 35 km, the volume and mass of the balloon is 1.5 cubic meters, and 3.5 kg, respectively. The shape of the balloon is chosen to be cylindrical with a small diameter. The mass of li fting gas can be determined as 4.3 kg and the remaining 2.2 kg becomes the payload mass. The mass of the total balloon system is also just 10 kg excluding the entry capsule.

Izutsu, N.; Yajima, N.; Honda, H.; Imamura, T.

31

Comparison of Stratospheric Aerosol and Gas Experiment (SAGE) II version 6.2 water vapor with balloon-borne and space-based instruments  

Microsoft Academic Search

A new version of the SAGE II data products was released in October 2003. The primary change to the algorithm dealt with improvements in the water vapor product such as eliminating the dry bias in the lower stratosphere and reducing the sensitivity to aerosol contamination. Results of an extensive comparison of SAGE II version 6.2 water vapor and various correlative

Ghassan Taha; Larry W. Thomason; Sharon P. Burton

2004-01-01

32

Does Air Contain Water Vapor?  

NSDL National Science Digital Library

In this activity, students monitor the change that takes place when water vapor condenses from a gas to a liquid and see how a change in temperature affects this transformation. Materials needed to conduct the investigation include two thermometers, a clear glass container, ice cubes and tap water. The resource includes background information, teaching tips and questions to guide student discussion. This is chapter 10 of Meteorology: An Educator's Resource for Inquiry-Based Learning for Grades 5-9. The guide includes a discussion of learning science, the use of inquiry in the classroom, instructions for making simple weather instruments, and more than 20 weather investigations ranging from teacher-centered to guided and open inquiry investigations.

33

Eyeing the Sky's Water Vapor  

NASA Technical Reports Server (NTRS)

This image, and many like it, are one way NASA's Phoenix Mars Lander is measuring trace amounts of water vapor in the atmosphere over far-northern Mars. Phoenix's Surface Stereo Imager (SSI) uses solar filters, or filters designed to image the sun, to make these images. The camera is aimed at the sky for long exposures.

SSI took this image as a test on June 9, 2008, which was the Phoenix mission's 15th Martian day, or sol, since landing, at 5:20 p.m. local solar time. The camera was pointed about 38 degrees above the horizon. The white dots in the sky are detector dark current that will be removed during image processing and analysis.

The Phoenix Mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is by NASA's Jet Propulsion Laboratory, Pasadena, Calif. Spacecraft development is by Lockheed Martin Space

2008-01-01

34

Simple Chemical Vapor Deposition Experiment  

ERIC Educational Resources Information Center

Chemical vapor deposition (CVD) is a process commonly used for the synthesis of thin films for several important technological applications, for example, microelectronics, hard coatings, and smart windows. Unfortunately, the complexity and prohibitive cost of CVD equipment makes it seldom available for undergraduate chemistry students. Here, a…

Pedersen, Henrik

2014-01-01

35

8, 44834498, 2008 Water vapor release  

E-print Network

monoxide and carbon dioxide are used to scale the concentra- tions of water vapor found, and are compared We report on the emission of water vapor from biofuel combustion. Concurrent mea- surements of carbon to carbon in the biofuel. Fuel types included hardwood (oak and African musasa), softwood (pine and spruce

Paris-Sud XI, Université de

36

Environmental Chemistry at Vapor/Water Interfaces  

E-print Network

Environmental Chemistry at Vapor/Water Interfaces: Insights from Vibrational Sum Frequency for manyyearsowingtoitscomplexityandimportanceindescribingawiderange of physical phenomena. The vapor/water interface is particularly interesting from an environmental chemistry perspective as this surface plays host to a wide range of chemistries that influence atmospheric

37

Impact vaporization: Late time phenomena from experiments  

NASA Technical Reports Server (NTRS)

While simple airflow produced by the outward movement of the ejecta curtain can be scaled to large dimensions, the interaction between an impact-vaporized component and the ejecta curtain is more complicated. The goal of these experiments was to examine such interaction in a real system involving crater growth, ejection of material, two phased mixtures of gas and dust, and strong pressure gradients. The results will be complemented by theoretical studies at laboratory scales in order to separate the various parameters for planetary scale processes. These experiments prompt, however, the following conclusions that may have relevance at broader scales. First, under near vacuum or low atmospheric pressures, an expanding vapor cloud scours the surrounding surface in advance of arriving ejecta. Second, the effect of early-time vaporization is relatively unimportant at late-times. Third, the overpressure created within the crater cavity by significant vaporization results in increased cratering efficiency and larger aspect ratios.

Schultz, P. H.; Gault, D. E.

1987-01-01

38

Water vapor retrieval from OMI visible spectra  

NASA Astrophysics Data System (ADS)

There are distinct spectral features of water vapor in the wavelength range covered by the Ozone Monitoring Instrument (OMI) visible channel. Although these features are much weaker than those at longer wavelengths, they can be exploited to retrieve useful information about water vapor. They have an advantage in that their small optical depth leads to fairly simple interpretation as measurements of the total water vapor column density. We have used the Smithsonian Astrophysical Observatory (SAO) OMI operational retrieval algorithm to derive the slant column density (SCD) of water vapor using the 430-480 nm spectral region after extensive optimization. We convert from SCD to vertical column density (VCD) using the air mass factor (AMF), which is calculated using look-up tables of scattering weights and assimilated water vapor profiles. Our Level 2 product includes not only water vapor VCD but also the associated scattering weights and AMF. In the tropics, our standard water vapor product has a median SCD of 1.3 × 1023 molecules cm-2 and a median relative uncertainty of about 11%, about a factor of 2 better than that from a similar OMI algorithm that uses a narrower retrieval window. The corresponding median VCD is about 1.2 × 1023 molecules cm-2. We have examined the sensitivities of SCD and AMF to various parameters and compared our results with those from the GlobVapour product, the Moderate Resolution Imaging Spectroradiometer (MODIS) and the Aerosol Robotic NETwork (AERONET).

Wang, H.; Liu, X.; Chance, K.; González Abad, G.; Miller, C. Chan

2014-06-01

39

Spacelab 3 vapor crystal growth experiment  

NASA Technical Reports Server (NTRS)

The Space Shuttle Challenger, with Spacelab 3 as its payload, was launched into orbit April 29, 1985. The mission, number 51-B, emphasized materials processing in space, although a wide variety of experiments in other disciplines were also carried onboard. One of the materials processing experiments on this flight is described, specifically the growth of single crystals of mercuric iodide by physical vapor transport.

Schnepple, W.; Vandenberg, L.; Skinner, N.; Ortale, C.

1987-01-01

40

Measuring Water Vapor with Differential Absorption Lidar  

NASA Astrophysics Data System (ADS)

Despite the need for global measurements of water vapor profiles with low bias and high vertical resolution there is currently no operational remote sensing system that would deliver such data. A possible solution to this problem is offered by the differential absorption lidar (DIAL) approach. The basic principle of operation will be described and some background on atmospheric light absorption by water vapor will be given. DLR's airborne water vapor DIAL system WALES represents the currently most advanced system worldwide using a multiwavelength technique to cover the troposphere and lower stratosphere simultaneously. A few examples of measurements made with this system will illustrate the power of this active remote sensing method.

Wirth, Martin

41

Vapor burn analysis for the Coyote series LNG spill experiments  

SciTech Connect

A major purpose of the Coyote series of field experiments at China Lake, California, in 1981 was to study the burning of vapor clouds from spills of liquefied natural gas (LNG) on water. Extensive arrays of instrumentation were deployed to obtain micrometeorological, gas concentration, and fire-related data. The instrumentation included in situ sensors of various types, high-speed motion picture cameras, and infrared (IR) imagers. Five of the total of ten Coyote spill experiments investigated vapor burns. The first vapor-burn experiment, Coyote 2, was done with a small spill of LNG to assess instrument capability and survivability in vapor cloud fires. The emphasis in this report is on the other four vapor-burn experiments: Coyotes 3, 5, 6, and 7. The data are analyzed to determine fire spread, flame propagation, and heat flux - quantities that are related to the determination of the damage zone for vapor burns. The results of the analyses are given here. 20 references, 57 figures, 7 tables.

Rodean, H.C.; Hogan, W.J.; Urtiew, P.A.; Goldwire, H.C. Jr.; McRae, T.G.; Morgan, D.L. Jr.

1984-04-01

42

AVIRIS Spectrometer Maps Total Water Vapor Column  

NASA Technical Reports Server (NTRS)

Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) processes maps of vertical-column abundances of water vapor in atmosphere with good precision and spatial resolution. Maps provide information for meteorology, climatology, and agriculture.

Conel, James E.; Green, Robert O.; Carrere, Veronique; Margolis, Jack S.; Alley, Ronald E.; Vane, Gregg A.; Bruegge, Carol J.; Gary, Bruce L.

1992-01-01

43

Anthropogenic water vapor emissions in Tokyo  

NASA Astrophysics Data System (ADS)

Temporal and spatial variations in anthropogenic water vapor (AWV) emissions and anthropogenic heat (AH) in Tokyo were estimated using data from a geographic information system (GIS) and an energy-consumption database. The maximum value of AWV exceeded 500 W m-2 in summer in central Tokyo. Estimations of AWV were validated with field-measured data. The estimated and measured data agreed well, indicating that anthropogenic sources such as district cooling systems release large amounts of water vapor into the atmosphere.

Moriwaki, Ryo; Kanda, Manabu; Senoo, Hiroshi; Hagishima, Aya; Kinouchi, Tsuyoshi

2008-11-01

44

Water vapor - Stratospheric injection by thunderstorms.  

NASA Technical Reports Server (NTRS)

Infrared radiometric inference measurements of the mass of water vapor injected into the lower stratosphere and upper troposphere by a number of plains thunderstorms show an average threefold increase over the fair weather background mass of water vapor. These airborne measurements, made from the National Aeronautics and Space Administration Convair 990 jet laboratory, extended over a sample size much larger than that possible by balloon and other techniques.

Kuhn, P. M.; Lojko, M. S.; Petersen, E. V.

1971-01-01

45

Optical monitor for water vapor concentration  

SciTech Connect

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

Kebabian, Paul (Acton, MA)

1998-01-01

46

Water vapor retrieval from OMI visible spectra  

NASA Astrophysics Data System (ADS)

There are distinct spectral features of water vapor in the wavelength range covered by the Ozone Monitoring Instrument (OMI) visible channel. Although these features are much weaker than those at longer wavelengths, they can be exploited to retrieve useful information about water vapor. They have an advantage in that their small optical depth leads to fairly simple interpretation as measurements of the total water vapor column density. We have used the Smithsonian Astrophysical Observatory (SAO)'s OMI operational retrieval algorithm to derive the Slant Column Density (SCD) of water vapor from OMI measurements using the 430-480 nm spectral region after extensive optimization of retrieval windows and parameters. The Air Mass Factor (AMF) is calculated using look-up tables of scattering weights and monthly mean water vapor profiles from the GEOS-5 assimilation products. We convert from SCD to Vertical Column Density (VCD) using the AMF and generate associated retrieval averaging kernels and shape factors. Our standard water vapor product has a median SCD of ~ 1.3 × 1023 molecule cm-2 and a median relative uncertainty of ~ 11% in the tropics, about a factor of 2 better than that from a similar OMI algorithm but using narrower retrieval window. The corresponding median VCD is ~ 1.2 × 1023 molecule cm-2. We have also explored the sensitivities to various parameters and compared our results with those from the Moderate-resolution Imaging Spectroradiometer (MODIS) and the Aerosol Robotic NETwork (AERONET).

Wang, H.; Liu, X.; Chance, K.; Gonzalez Abad, G.; Miller, C. Chan

2014-01-01

47

Vacuum distillation/vapor filtration water recovery  

NASA Technical Reports Server (NTRS)

The development and evaluation of a vacuum distillation/vapor filtration (VD/VF) water recovery system are considered. As a functional model, the system converts urine and condensates waste water from six men to potable water on a steady-state basis. The system is designed for 180-day operating durations and for function on the ground, on zero-g aircraft, and in orbit. Preparatory tasks are summarized for conducting low gravity tests of a vacuum distillation/vapor filtration system for recovering water from urine.

Honegger, R. J.; Neveril, R. B.; Remus, G. A.

1974-01-01

48

Effect of Salt Additives to Water on the Severity of Vapor Explosions and on the Collapse of Vapor Film  

NASA Astrophysics Data System (ADS)

We proposed ultra rapid solidification and atomization technique, CANOPUS (Cooling and Atomizing based on NOble Process Utilizing Steam explosion), using small-scale vapor explosions to make an amorphous metal. The CANOPUS method is suitable for rapid cooling and atomization process, which utilizing sustainable small-scale vapor explosions. In order to apply the CANOPUS method to a high melting point metal, it is necessary to make a small-scale vapor explosion occur at a high temperature of the molten metal. Small-scale experiment is conducted to develop the vapor explosion promotor in which spontaneous vapor explosion can occur at a high temperature of a molten metal. Spontaneous vapor explosion do not occur when water at 80°C is used as a coolant. However, spontaneous vapor explosion occurs when water at 80°C with salt additives is used as a coolant. Specifically, lithium chloride solution generates spontaneous vapor explosions at the highest temperature of the molten tin in the experiment. In order to clarify the triggering mechanism of the spontaneous vapor explosion when the promotor is used as a coolant, a high-temperature solid stainless steel sphere is immersed into a coolant. The interfacial temperature of the stainless steel sphere is measured, and the behavior of a vapor film around the stainless steel sphere is observed with a digital video camera. As a result, salt additives resulted in an increase of quench temperature in all salt solutions. The quenching curves of each coolant indicate that the salt additives improve the film boiling heat transfer. The improvement of the film boiling heat transfer causes an unstable formation of the vapor film and a rise of the quench temperature. It is clarified that the salt additives to water promotes a vapor film collapse. Comparing two experiments, the quench temperature of each solution is in close agreement with the upper limit of the molten tin temperature that causes spontaneous vapor explosion. This result suggests that the vapor film collapse triggers spontaneous vapor explosion.

Arai, Takahiro; Furuya, Masahiro

49

Characterization of upper troposphere water vapor measurements during AFWEX using LASE.  

SciTech Connect

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

Ferrare, R. A.; Browell, E. V.; Ismail, I.; Kooi, S.; Brasseur, L. H.; Brackett, V. G.; Clayton, M.; Barrick, J.; Bosenberg, J.; Diskin, G.; Goldsmith, J.; Lesht, B.; Podolske, J.; Sachse, G.; Schmidlin, F. J.; Turner, D.; Whitemann, D.

2002-07-15

50

Distribution of tropical tropospheric water vapor  

NASA Technical Reports Server (NTRS)

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

Sun, De-Zheng; Lindzen, Richard S.

1993-01-01

51

Water vapor adsorption on plutonium dioxide  

Microsoft Academic Search

Adsorption isotherms of water vapor on plutonium dioxide were measured ; gravimetrically at 30, 50, and 85 deg C. The data show water to be irreversibly ; chemisorbed until the oxide is saturated. Any subsequent adsorption is physical ; and completely reversible. The chemisorbed limit varied from 1 monolayer at 85 ; deg C to 3 monolayers at 30 deg

J. L. Stakebake; L. M. Steward

1973-01-01

52

Measurements of water vapor in Mars' antarctic  

NASA Technical Reports Server (NTRS)

A complete Mars year of measurements of atmospheric water vapor in the south arctic have been obtained from the Viking Orbiters. Analysis of the observations indicates that, except for the south remnant cap, the southern hemisphere of Mars is devoid of any substantial reservoirs of water in contact with the atmosphere, and that, in the summer time, the top layer of soil is desiccated. Small amounts of water ice are incorporated into the annual CO2 cap; this water is released at the cap margin when it retreats in the spring. The first global dust storm resulted in heating of the south arctic atmosphere and a transport of water in from the equatorial region. The second global dust storm had a negligible effect on atmospheric water vapor; the dust contained little water.

Davies, D. W.; Wainio, L. A.

1981-01-01

53

High temperature measurement of water vapor absorption  

NASA Technical Reports Server (NTRS)

An investigation was undertaken to measure the absorption coefficient, at a wavelength of 10.6 microns, for mixtures of water vapor and a diluent gas at high temperature and pressure. The experimental concept was to create the desired conditions of temperature and pressure in a laser absorption wave, similar to that which would be created in a laser propulsion system. A simplified numerical model was developed to predict the characteristics of the absorption wave and to estimate the laser intensity threshold for initiation. A non-intrusive method for temperature measurement utilizing optical laser-beam deflection (OLD) and optical spark breakdown produced by an excimer laser, was thoroughly investigated and found suitable for the non-equilibrium conditions expected in the wave. Experiments were performed to verify the temperature measurement technique, to screen possible materials for surface initiation of the laser absorption wave and to attempt to initiate an absorption wave using the 1.5 kW carbon dioxide laser. The OLD technique was proven for air and for argon, but spark breakdown could not be produced in helium. It was not possible to initiate a laser absorption wave in mixtures of water and helium or water and argon using the 1.5 kW laser, a result which was consistent with the model prediction.

Keefer, Dennis; Lewis, J. W. L.; Eskridge, Richard

1985-01-01

54

Vapor-liquid equilibrium of amine-water systems  

E-print Network

extraction method for saline water conversion. The investigation of vapor-liquid equilibrium relationships of the solutions of amine and water is an important step towards correlating the effect of molecular structure on the thermodynamic properties... of the interesting properties of water solutions of methyldiethyl amine and other tertiary amines . The work presented here involves the construction of an experi- mental apparatus, and presentation of data determined using that appara- tus for the system of 5...

Chun, Kil Whan

2012-06-07

55

Persistent disparities in stratospheric water vapor measurements drive large uncertainties in the radiative forcing by lower stratospheric water vapor  

NASA Astrophysics Data System (ADS)

Lower stratospheric water vapor is a powerful attenuator of outgoing long wave radiation, hence its strong influence on the Earth's radiation budget. The radiative forcing by lower stratospheric water vapor is, however, quite uncertain because of significant disparities in lower stratospheric water vapor measurements by different instruments. Specifically, measurement discrepancies of 0.5 to 2 ppmv H2O (15 to 60%) between several well-established aircraft- and balloon-borne instruments have now persisted for almost two decades. The Mid-latitude Airborne Cirrus Properties Experiment (MACPEX) in April 2011 provided not only a fresh opportunity to reexamine and reevaluate these persistent measurement discrepancies, but also to compare water vapor measurements by additional aircraft-based instrumentation. Here we compare the in situ measurements of lower stratospheric water vapor by five different instruments during MACPEX. Three of these instruments (Harvard water, FISH, and NOAA CIMS) were aboard the NASA WB-57 aircraft, while two (CFH and NOAA FPH) were launched on balloons. Substantial efforts were made to coordinate aircraft and balloon measurements in space and time, such that the aircraft would reach maximum altitude en route to the balloon rendezvous point, then both aircraft and balloon would descend together. Lower stratospheric water vapor measurements during MACPEX generally fall into two groups: CFH, NOAA FPH and FISH are in good agreement, while Harvard water and NOAA CIMS agree with each other but are significantly different than the other group. Differences between the two groups range from 0.5 to 1.0 ppmv (15 to 30%), with Harvard and NOAA CIMS mixing ratios consistently higher. Though these differences seem relatively large, they are smaller than some previously observed differences between the FPH/CFH and Harvard water. For example, Harvard stratospheric water vapor measurements during the 1993 CEPEX and 2006 CR-AVE campaigns were 1.5 and 2 ppmv greater, respectively, than the FPH/CFH measurements. Radiative transfer calculations employing the two disparate sets of water vapor profiles measured during MACPEX yield significantly different forcings for lower stratospheric water vapor. More accurate calculations are not possible until the ongoing measurement discrepancy is further reduced or eliminated. The smaller measurement discrepancies observed during MACPEX, though still statistically significant, have spawned renewed attempts to understand the root cause(s) of these measurement differences.

Hurst, D. F.; Rosenlof, K. H.; Portmann, R. W.; Voemel, H.; Schiller, C.; Smith, J. B.; Thornberry, T. D.; Rollins, A. W.; Hall, E.; Jordan, A.; Oltmans, S. J.

2011-12-01

56

Vapor explosions: A review of experiments for accident analysis  

SciTech Connect

A vapor explosion is a physical event in which a hot liquid (fuel) transfers its internal energy to a colder, more volatile liquid (coolant); thus the coolant vaporizes at high pressures and expands analyses work on its surroundings. In postulated severe accidents in current fission reactors, vapor explosions are considered if this molten {open_quotes}fuel{close_quotes} contacts residual water in-vessel or ex-vessel because these physical explosions have the potential to contribute to reactor vessel failure and possibly containment failure and release of radioactive fission products. Current safety analyses and probabilistic studies consider this process with the use of explosion models. Eventually these models must be compared with available experimental data to determine their validity. This study provides a comprehensive review of vapor explosion experiments for eventual use in such comparisons. Also, when there are insufficient data, experiments are suggested that can provide the needed information for future comparisons. This view may be useful for light-water-reactor as well as noncommercial reactor safety studies. 115 refs., 6 figs., 3 tabs.

Corradini, M.L.; Taleyarkhan, R.P.

1991-07-01

57

A FGGE water vapor wind data set  

NASA Technical Reports Server (NTRS)

It has been recognized for some time that water vapor structure visible in infrared imagery offers a potential for obtaining motion vectors when several images are considered in sequence (Fischer et al., 1981). A study evaluating water vapor winds obtained from the VISSR atmospheric sounder (Stewart et al., 1985) has confirmed the viability of the approach. More recently, 20 data sets have been produced from METEOSAT water vapor imagery for the FGGE period of 10-25 November 1979. Where possible, two data sets were prepared for each day at 0000 and 1200 GMT and compared with rawinsondes over Europe, Africa, and aircraft observations over the oceans. Procedures for obtaining winds were, in general, similar to the earlier study. Motions were detected both by a single pixel tracking and a cross correlation method by using three images individually separated by one hour. A height assignment was determined by matching the measured brightness temperature to the temperature structure represented by the FGGE-IIIB analyses. Results show that the METEOSAT water vapor winds provide uniform horizontal coverage of mid-level flow over the globe with good accuracy.

Stewart, Tod R.; Hayden, Christopher M.

1985-01-01

58

Applications II: Water Vapor and Atmospheric Dynamics  

NASA Technical Reports Server (NTRS)

Contents include the following: 1. Introduction. A case for using lidars in atmospheric dynamics will be made. 2. Scales of motion. Will discuss atmospheric scales of motion and lidar role in probing this various events. 3. Examples. We will discuss applications of lidars into atmospheric dynamics using data from case studies that illustrate different atmospheric phenomenon. Concluding statement. Water Vapor and Atmospheric Dynamics.

Demoz, Belay

2004-01-01

59

GOES Water Vapor: 1995 Hurricane Season  

NSDL National Science Digital Library

An animation of atmospheric water vapor over the Western Hemisphere for the period from May 5, 1995 through October 31, 1995, as measured by GOES. The animation shows the entire hemisphere, then zooms in to show the North Atlantic and the hurricanes during this period.

Shirah, Greg; Kekesi, Alex; Chesters, Dennis; Hasler, Fritz

1998-01-01

60

Characterization of Advanced Avalanche Photodiodes for Water Vapor Lidar Receivers  

NASA Technical Reports Server (NTRS)

Development of advanced differential absorption lidar (DIAL) receivers is very important to increase the accuracy of atmospheric water vapor measurements. A major component of such receivers is the optical detector. In the near-infrared wavelength range avalanche photodiodes (APD's) are the best choice for higher signal-to-noise ratio, where there are many water vapor absorption lines. In this study, characterization experiments were performed to evaluate a group of silicon-based APD's. The APD's have different structures representative of different manufacturers. The experiments include setups to calibrate these devices, as well as characterization of the effects of voltage bias and temperature on the responsivity, surface scans, noise measurements, and frequency response measurements. For each experiment, the setup, procedure, data analysis, and results are given and discussed. This research was done to choose a suitable APD detector for the development of an advanced atmospheric water vapor differential absorption lidar detection system operating either at 720, 820, or 940 nm. The results point out the benefits of using the super low ionization ratio (SLIK) structure APD for its lower noise-equivalent power, which was found to be on the order of 2 to 4 fW/Hz(sup (1/2)), with an appropriate optical system and electronics. The water vapor detection systems signal-to-noise ratio will increase by a factor of 10.

Refaat, Tamer F.; Halama, Gary E.; DeYoung, Russell J.

2000-01-01

61

Water vapor distribution in protoplanetary disks  

E-print Network

Water vapor has been detected in protoplanetary disks. In this work we model the distribution of water vapor in protoplanetary disks with a thermo-chemical code. For a set of parameterized disk models, we calculate the distribution of dust temperature and radiation field of the disk with a Monte Carlo method, and then solve the gas temperature distribution and chemical composition. The radiative transfer includes detailed treatment of scattering by atomic hydrogen and absorption by water of Lyman alpha photons, since the Lyman alpha line dominates the UV spectrum of accreting young stars. In a fiducial model, we find that warm water vapor with temperature around 300 K is mainly distributed in a small and well-confined region in the inner disk. The inner boundary of the warm water region is where the shielding of UV field due to dust and water itself become significant. The outer boundary is where the dust temperature drops below the water condensation temperature. A more luminous central star leads to a more ...

Du, Fujun

2014-01-01

62

Mars: Water Vapor Observations From the Viking Orbiters  

Microsoft Academic Search

The results of observations of the spatial and temporal variation of water vapor during the Viking primary mission are reported. The instrument, the Mars atmospheric water detector (Mawd), is a fivechannel grating spectrometer operating in the 1.4-tm water vapor bands. The seasonal period covered here is the northern summer solstice to the following equinox. The global water vapor, mapped at

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

1977-01-01

63

Visualization of Atmospheric Water Vapor Data for SAGE  

NASA Technical Reports Server (NTRS)

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

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

2000-01-01

64

21 CFR 868.1975 - Water vapor analyzer.  

Code of Federal Regulations, 2011 CFR

A water vapor analyzer is a device intended to measure the concentration of water vapor in a patient's expired gases by using techniques such as mass spectrometry. (b) Classification. Class I (general...

2011-04-01

65

21 CFR 868.1975 - Water vapor analyzer.  

Code of Federal Regulations, 2012 CFR

A water vapor analyzer is a device intended to measure the concentration of water vapor in a patient's expired gases by using techniques such as mass spectrometry. (b) Classification. Class I (general...

2012-04-01

66

Tunable lasers for water vapor measurements and other lidar applications  

NASA Technical Reports Server (NTRS)

A tunable dye laser suitable for differential absorption (DIAL) measurements of water vapor in the troposphere was constructed. A multi-pass absorption cell for calibration was also constructed for use in atmospheric DIAL measurements of water vapor.

Gammon, R. W.; Mcilrath, T. J.; Wilkerson, T. D.

1977-01-01

67

Micromachined water vapor sensors: a review of sensing technologies  

Microsoft Academic Search

The measurement of water vapor is important in many applications ranging from predicting changes in the weather to ensuring heating and cooling comfort in homes. In manufacturing, water vapor measurements help to control performance properties of engineered materials and optimize fuel efficiency in power generation. This paper presents a technology review of water vapor sensors and manufacturing techniques. Micromachining, more

Ralph Fenner; Edward Zdankiewicz

2001-01-01

68

Effect of higher water vapor content on TBC performance  

SciTech Connect

Coal gasification, or IGCC (integrated gasification combined cycle), is one pathway toward cleaner use of coal for power generation with lower emissions. However, when coal-derived synthesis gas (i.e., syngas) is burned in turbines designed for natural gas, turbine manufacturers recommend 'derating,' or lowering the maximum temperature, which lowers the efficiency of the turbine, making electricity from IGCC more expensive. One possible reason for the derating is the higher water vapor contents in the exhaust gas. Water vapor has a detrimental effect on many oxidation-resistant high-temperature materials. In a turbine hot section, Ni-base superalloys are coated with a thermal barrier coating (TBC) allowing the gas temperature to be higher than the superalloy solidus temperature. TBCs have a low thermal conductivity ceramic top coating (typically Y{sub 2}O{sub 3}-stabilized ZrO{sub 2}, or YSZ) and an oxidation-resistant metallic bond coating. For land-based gas turbines, the industry standard is air plasma sprayed (APS) YSZ and high velocity oxygen fuel (HVOF) sprayed NiCoCrAlY bond coatings. To investigate the role of higher water vapor content on TBC performance and possible mitigation strategies, furnace cycling experiments were conducted in dry O{sub 2} and air with 10% (typical with natural gas or jet fuel) or 50 vol% water vapor. Cycle frequency and temperature were accelerated to one hour at 1100 C (with 10 minute cooling to {approx}30 C between each thermal cycle) to induce early failures in coatings that are expected to operate for several years with a metal temperature of {approx}900 C. Coupons (16 mm diameter x 2 mm thick) of commercial second-generation single crystal superalloy CMSX4 were HVOF coated on both sides with {approx}125 {micro}m of Ni-22wt%Co-17Cr-12Al either with 0.7Y or 0.7Y-0.3Hf-0.4Si. One side was then coated with 190-240 {micro}m of APS YSZ. Coatings were cycled until the YSZ top coating spalled. Figure 2 shows the results of the initial phase of experiments. Compared to dry O{sub 2}, the addition of 10% water vapor decreased the lifetime of MCrAlY by {approx}30% for the conventional CMSX4 substrates. Higher average lifetimes were observed with Hf in the bond coating, but a similar decrease in lifetime was observed when water vapor was added. The addition of Y and La to the superalloy substrate did not change the YSZ lifetime with 10% water vapor. However, increasing water vapor content from 10 to 50% did not further decrease the lifetime of either bond coating with the doped superalloy substrate. Thus, these results suggest that higher water vapor contents cannot explain the derating of syngas-fired turbines, and other factors such as sulfur and ash from imperfect syngas cleanup (or upset conditions) need to be explored. Researchers continue to study effects of water vapor on thermally grown alumina scale adhesion and growth rate, and are looking for bond coating compositions more resistant to oxidation in the presence of water vapor.

Pint, Bruce A [ORNL; Haynes, James A [ORNL

2012-01-01

69

Inferring water vapor amounts with solar spectral irradiance: Measurements, modeling, and comparisons with in situ water vapor profiles in the upper troposphere lower stratosphere from ATTREX  

NASA Astrophysics Data System (ADS)

The Airborne Tropical TRopopause Experiment (ATTREX) flew six science missions on the NASA Global Hawk aircraft from NASA Dryden, California to the Pacific tropics to sample the upper troposphere, lower stratosphere (UTLS) during February and March of 2013. After transit to the tropics, the aircraft performed a series of vertical profiles from the cruising altitude of about 18 km down to 14 km sampling the tropical tropopause layer (TTL). A science focus of ATTREX is to examine water vapor and its transport through the TTL. The extremely cold temperatures found in the TTL act to limit the transport of water vapor from the troposphere to stratosphere, making this region critical to the water vapor budget of the stratosphere. Here we investigate the use of the strong water bands centered at 1400 and 1900 nm in the telluric solar spectrum to infer the small water vapor amounts through the TTL. Measurements of spectral irradiance from the Solar Spectral Flux Radiometer (SSFR) at the top and bottom of the aircraft profiles are used to produce transmission spectra. These are compared with atmospheric radiative transfer calculations of transmission through the layer. The measured water vapor profile from the NOAA water vapor instrument, as well as temperature and pressure, were used in the modeling, providing a rare opportunity to compare water vapor amount inferred from solar transmittance to in situ measurements. Prospects for the use of these bands for determining the total column water vapor amount from the UTLS to the top of the atmosphere from aircraft are also discussed.

Kindel, B. C.; Pilewskie, P.; Schmidt, S.; Thornberry, T. D.; Rollins, D. W.; LeBlanc, S. E.; Bui, T. V.

2013-12-01

70

Quality and Control of Water Vapor Winds  

NASA Technical Reports Server (NTRS)

Water vapor imagery from the geostationary satellites such as GOES, Meteosat, and GMS provides synoptic views of dynamical events on a continual basis. Because the imagery represents a non-linear combination of mid- and upper-tropospheric thermodynamic parameters (three-dimensional variations in temperature and humidity), video loops of these image products provide enlightening views of regional flow fields, the movement of tropical and extratropical storm systems, the transfer of moisture between hemispheres and from the tropics to the mid- latitudes, and the dominance of high pressure systems over particular regions of the Earth. Despite the obvious larger scale features, the water vapor imagery contains significant image variability down to the single 8 km GOES pixel. These features can be quantitatively identified and tracked from one time to the next using various image processing techniques. Merrill et al. (1991), Hayden and Schmidt (1992), and Laurent (1993) have documented the operational procedures and capabilities of NOAA and ESOC to produce cloud and water vapor winds. These techniques employ standard correlation and template matching approaches to wind tracking and use qualitative and quantitative procedures to eliminate bad wind vectors from the wind data set. Techniques have also been developed to improve the quality of the operational winds though robust editing procedures (Hayden and Veldon 1991). These quality and control approaches have limitations, are often subjective, and constrain wind variability to be consistent with model derived wind fields. This paper describes research focused on the refinement of objective quality and control parameters for water vapor wind vector data sets. New quality and control measures are developed and employed to provide a more robust wind data set for climate analysis, data assimilation studies, as well as operational weather forecasting. The parameters are applicable to cloud-tracked winds as well with minor modifications. The improvement in winds through use of these new quality and control parameters is measured without the use of rawinsonde or modeled wind field data and compared with other approaches.

Jedlovec, Gary J.; Atkinson, Robert J.

1996-01-01

71

Development of an Airborne Micropulse Water Vapor DIAL  

NASA Astrophysics Data System (ADS)

Water vapor plays a key role in many atmospheric processes affecting both weather and climate. Airborne measurements of tropospheric water vapor profiles have been a longstanding observational need to not only the active remote sensing community but also to the meteorological, weather forecasting, and climate/radiation science communities. Microscale measurements of tropospheric water vapor are important for enhancing near term meteorological forecasting capabilities while mesoscale and synopticscale measurements can lead to an enhanced understanding of the complex coupled feedback mechanisms between water vapor, temperature, aerosols, and clouds. To realize tropospheric measurements of water vapor profiles over the microscale-synopticscale areas of meteorological interest, a compact and cost effective airborne micropulse differential absorption lidar (DIAL) is being investigated using newly emerging semiconductor based laser technology. Ground based micropulse DIAL (MPD) measurements of tropospheric water vapor and aerosol profiles up to 6 km and 15 km, respectively, have been previously demonstrated using an all semiconductor based laser transmitter. The DIAL transmitter utilizes a master oscillator power amplifier (MOPA) configuration where two semiconductor seed lasers are used to seed a single pass traveling wave tapered semiconductor optical amplifier (TSOA), producing up to 7?J pulse energies over a 1 ?s pulse duration at a 10 kHz pulse repetition frequency (PRF). Intercomparisons between the ground based instrument measurements and radiosonde profiles demonstrating the MPD performance under varying atmospheric conditions will be presented. Work is currently ongoing to expand upon the ground based MPD concept and to develop a compact and cost effective system capable of deployment on a mid-low altitude aircraft such as the NASA Langley B200 King Air. Initial lab experiments show that a two-three fold increase in the laser energy compared to the ground based instrument is achievable via overdriven current pulses to the TSOA gain medium while maintaining a 1?s and 10 kHz pulse width and PRF, respectively. The increase in the laser transmitter pulse energy will allow for nighttime and daytime water vapor profile retrievals from an airborne platform operating at an 8 km altitude with 2-5 minute integration periods. Results from a numerical model demonstrating the performance of an airborne DIAL system with the mentioned transmitter enhancements will be presented and compared against the existing ground based instrument performance. Furthermore, results from laboratory experiments demonstrating the laser transmitter performance including maximum extractable energy, energy stability, and spectral purity will also be presented.

Nehrir, A. R.; Ismail, S.

2012-12-01

72

Effect of Acids on Water Vapor Uptake by Pyrogenic Silica  

PubMed

Effect of gaseous HCl and HNO3 on the water vapor uptake by pyrogenic silica was studied at different relative humidities (RH) for pure water and different compositions of binary and ternary vapor mixtures. Experiments showed that the ability of silica to uptake water strongly depends on RH and on the type of acids and their concentration in the vapor mixtures. At low acid concentration in the binary mixtures the influence of acids is probably small. Water uptake by silica does not change monotonically with acid concentration: at first it decreases and then starts to grow. However, the presence of acids promotes water uptake, and the effect is very significant at low RH. HCl seems to be more effective acid to enhance water uptake than HNO3 . In the case of ternary mixtures the adsorbed weight of water is a bit larger than that adsorbed from the binary mixtures. Acids are accumulated by silica surface, and the accumulation is larger for nitric acid. PMID:9241208

Bogdan; Kulmala

1997-07-01

73

Cumulus convection and the terrestrial water-vapor distribution  

NASA Technical Reports Server (NTRS)

Cumulus convection plays a significant role in determining the structure of the terrestrial water vapor field. Cumulus convection acts directly on the moisture field by condensing and precipitating water vapor and by redistributing water vapor through cumulus induced eddy circulations. The mechanisms by which cumulus convection influences the terrestrial water vapor distribution is outlined. Calculations using a theory due to Kuo is used to illustrate the mechanisms by which cumulus convection works. Understanding of these processes greatly aids the ability of researchers to interpret the seasonal and spatial distribution of atmospheric water vapor by providing information on the nature of sources and sinks and the global circulation.

Donner, Leo J.

1988-01-01

74

Reaction rate constant for uranium in water and water vapor  

SciTech Connect

The literature on uranium oxidation in water and oxygen free water vapor was reviewed. Arrhenius rate equations were developed from the review data. These data and equations will be used as a baseline from which to compare reaction rates measured for K Basin fuel.

TRIMBLE, D.J.

1998-11-09

75

Hydrogen isotope measurement corrections for low water vapor concentrations: Mauna Loa Observatory, Hawaii  

Microsoft Academic Search

We present a comparison of laser spectroscopy measurements and traditional mass spectrometry techniques for measuring the hydrogen isotope composition of atmospheric water vapor. Laboratory experiments indicate that the Picarro gas analyzer has a negative relationship between inverse concentration and D\\/H ratio, so flask measurements were used to calibrate the laser spectroscopy systems at low water vapor concentrations and assess linearity.

L. R. Johnson; Z. D. Sharp; J. Galewsky; M. H. Strong; A. D. van Pelt; F. Dong; D. C. Noone

2010-01-01

76

Assimilation of TES Water Vapor Observations  

NASA Technical Reports Server (NTRS)

The Thermal Emission Spectrometer (TES) on the Mars Global Surveyor has made extensive observations of the Martian atmospheric water vapor column since the beginning of its mapping mission in early 1999. The results show broad agreement with the earlier Viking Mars Atmospheric Water Detector (MAWD) results (though column amounts in southern summer are higher, perhaps due to dust obscuration during the Viking mission). General circulation model (GCM) simulations of the annual Martian water cycle also show broad agreement with the TES observations. Details of the simulations depend on cloud and boundary layer parameterizations and on the adsorbing properties of the regolith. In order to make quantitative assessments of this agreement and to obtain observational values for the required physical parameters, a tracer transport data assimilation model has been developed. Model winds are derived from both tracer measurements and retrieved atmospheric temperature structures, providing a useful check of the underlying dynamical core of the GCM. By allowing detailed intercomparison between spacecraft and ground-based observations of Martian water vapor, the model should also contribute significantly to our understanding of the diurnal water cycle.

Houben, Howard; DeVincenzi, D. (Technical Monitor)

2002-01-01

77

Water Vapor Effects on Silica-Forming Ceramics  

NASA Technical Reports Server (NTRS)

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

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

2000-01-01

78

Diagnostics of land surface spatial variability and water vapor flux  

Microsoft Academic Search

To assess the spatial variability of the water vapor (i.e., latent heat) flux LE, it is convenient to scale it with its equilibrium analog LEe. From an analysis of the data from the First International Satellite Land Surface Climatology Project (ISLSCP) Field Experiment, or FIFE, the spatial distribution of daily values of this dimensionless evaporation, alpha=LE\\/LEe, was found to be

Daoyi Chen; Wilfried Brutsaert

1995-01-01

79

Study of the 10 micron continuum of water vapor  

NASA Technical Reports Server (NTRS)

Radiation attenuation by atmospheric water vapor is considered. A formula based on laboratory data is recommended for approximating continuous absorption in the spectra region in question. Data of full scale measurements and laboratory experiments are compared. It was concluded that only molecular absorption need be taken into account under clear atmospheric conditions during the warm part of the year, while in winter or in cloudy conditions, the effect of aerosol can be significant.

Arefyev, V. N.; Dianov-Klokov, V. I.; Ivanov, V. M.; Sizov, N. I.

1979-01-01

80

Trapping of water vapor from an atmosphere by condensed silicate matter formed by high-temperature pulse vaporization  

NASA Technical Reports Server (NTRS)

The origin of planetary atmospheres is thought to be the result of bombardment of a growing planet by massive planetesimals. According to some models, the accumulation of released water vapor and/or carbon dioxide can result in the formation of a dense and hot primordial atmosphere. Among source and sink processes of atmospheric water vapor the formation of hydroxides was considered mainly as rehydration of dehydrated minerals (foresterite and enstatite). From our point of view, the formation of hydroxides is not limited to rehydration. Condensation of small silicate particles in a spreading vapor cloud and their interaction with a wet atmosphere can also result in the origin of hydrated phases which have no genetic connections with initial water bearing minerals. We present results of two experiments of a simulated interaction of condensed silicate matter which originated during vaporization of dry clinopyroxene in a wet helium atmosphere.

Gerasimov, M. V.; Dikov, Yu. P.; Yakovlev, O. I.; Wlotzka, F.

1993-01-01

81

LASE measurements of aerosols and water vapor during TARFOX  

NASA Technical Reports Server (NTRS)

The TARFOX (Tropospheric Aerosol Radiative Forcing Observational Experiment) intensive field campaign was designed to reduce uncertainties in estimates of the effects of anthropogenic aerosols on climate by measuring direct radiative effects and the optical, physical, and chemical properties of aerosols [1]. TARFOX was conducted off the East Coast of the United States between July 10-31, 1996. Ground, aircraft, and satellite-based sensors measured the sensitivity of radiative fields at various atmospheric levels to aerosol optical properties (i.e., optical thickness, phase function, single-scattering albedo) and to the vertical profile of aerosols. The LASE (Lidar Atmospheric Sensing Experiment) instrument, which was flown on the NASA ER-2 aircraft, measured vertical profiles of total scattering ratio and water vapor during a series of 9 flights. These profiles were used in real-time to help direct the other aircraft to the appropriate altitudes for intensive sampling of aerosol layers. We have subsequently used the LASE aerosol data to derive aerosol backscattering and extinction profiles. Using these aerosol extinction profiles, we derived estimates of aerosol optical thickness (AOT) and compared these with measurements of AOT from both ground and airborne sun photometers and derived from the ATSR-2 (Along Track and Scanning Radiometer 2) sensor on ERS-2 (European Remote Sensing Satellite-2). We also used the water vapor mixing ratio profiles measured simultaneously by LASE to derive precipitable water vapor and compare these to ground based measurements.

Ferrare, Richard A.; Ismail, Syed; Browell, Edward V.; Brackett, Vincent G.; Kooi, Susan A.; Clayton, Marian B.; Melfi, Harvey; Whiteman, David N.; Schwenner, Geary; Evans, Keith D.; Hobbs, Peter V.; Veefkind, J. Pepijn; Russell, Philip B.; Livingston, John M.; Hignett, Philip; Holben, Brent N.; Remer, Lorraine A.

1998-01-01

82

Calibration of Atmospherically Induced Delay Fluctuations Due to Water Vapor  

NASA Technical Reports Server (NTRS)

We have completed a new generation of water vapor radiometers (WVR), the A- series, in order to support radio science experiments with the Cassini spacecraft. These new instruments sense three frequencies in the vicinity of the 22 GHz emission line of atmospheric water vapor within a 1 degree beamwidth from a clear aperture antenna that is co-pointed with the radio telescope down to 10 degree elevation. The radiometer electronics features almost an order of magnitude improvement in temperature stability compared with earlier WVR designs. For many radio science experiments, the error budget is likely to be dominated by path delay fluctuations due to variable atmospheric water vapor along the line-of-sight to the spacecraft. In order to demonstrate the performance of these new WVRs we are attempting to calibrate the delay fluctuations as seen by a radio interferometer operating over a 21 km baseline with a WVR near each antenna. The characteristics of these new WVRs will be described and the results of our preliminary analysis will be presented indicating an accuracy of 0.2 to 0.5 mm in tracking path delay fluctuations over time scales of 10 to 10,000 seconds.

Resch, George; Jacobs, Christopher; Keihm, Steve; Lanyi, Gabor; Naudet, Charles; Riley, Abraham; Rosenberger, Hans; Tanner, Alan

2000-01-01

83

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

NASA Astrophysics Data System (ADS)

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

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

2009-12-01

84

Experimental study of vapor explosion with water and R-22  

SciTech Connect

The term [open quotes]vapor explosion[close quotes] refers to a phenomenon in which the molten fuel rapidly fragments and transfers its energy to the coolant, resulting in vapor shock waves and possible mechanical damage. If such an event occurs during a severe accident in a nuclear power plant, the integrity of the reactor vessel and/or containment is highly threatened. Thus, numerous experiments have been performed to understand its mechanism and energy generation with various simulant materials. However, many questions are still unanswered about the mixing mechanism, conversion ratio, parametric effects, and so on. The purpose of the experiment discussed in this paper is to investigate the parametric effects on a steam explosion: water depth, corium mass, temperature, and pouring velocity. The simulant materials for corium and water are hot water (70 to 90[degrees]C) and Freon-22 ([minus]41[degrees]C), respectively. The experiments are performed by injecting the hot water on refrigerant R-22 liquid, and the explosion pressure and mechanical energy are measured.

Park, I.-G.; Jo, S.Y.; chung, C.H.; Park, G.-C. (Seoul National Univ., Kwanak-Gu (Korea, Republic of))

1993-01-01

85

Support for the Harvard University Water Vapor and Total Water Instruments for the 2004 NASA WB57 Middle Latitude Cirrus Experiment  

NASA Technical Reports Server (NTRS)

In order to improve our understanding of the role clouds play in the climate system, NASA is investing considerable effort in characterizing clouds with instruments ranging from passive remote sensors on board the EOS platforms, to the forthcoming active remote sensors on Cloudsat and Calipso. These missions, when taken together, have the capacity to advance our understanding of the coupling between various components of the hydrologic cycle and the atmospheric circulation, and hold the additional potential of leading to significant improvements in the characterization of cloud feedbacks in global models. This is especially true considering that several of these platforms will be flown in an identical orbit within several minutes of one another-a constellation of satellites known as the A-Train. The algorithms that are being implemented and developed to convert these new data streams from radiance and reflectivity measurements into geophysical parameters invariably rely on some set of simplifymg assumptions and empirical constants. Uncertainties in these relationships lead to poorly understood random and systematic errors in the retrieved properties. This lack of understanding introduces ambiguity in interpreting the data and in using the global data sets for their intended purposes. In light of this, a series of flights with the W57F was proposed to address certain specific issues related to the basic properties of mid latitude cirrus clouds: the NASA WE357 Middle Latitude Cirrus Experiment ("MidCiX"). The science questions addressed are: 1) Can cloud property retrieval algorithms developed for A-Train active and passive remote sensing measurements accurately characterize the microphysical properties of synoptic and convectively generated cirrus cloud systems? 2) What are the relationships between the cirrus particle mass, projected area, and particle size spectrum in various genre of cirrus clouds? 3) Does the present compliment of state of the art in situ cloud probes provide the level of precision and accuracy needed to develop and validate algorithms and to contribute to our understanding of the characteristics and microphysical processes operating in cirrus clouds?

Anderson, James G.

2005-01-01

86

Hurricane Isabel, Amount of Atmospheric Water Vapor Observed By AIRS  

NASA Technical Reports Server (NTRS)

[figure removed for brevity, see original site] Figure 1

These false-color images show the amount of atmospheric water vapor observed by AIRS two weeks prior to the passage of Hurricane Isabel, and then when it was a Category 5 storm. The region shown includes parts of South America and the West Indies. Puerto Rico is the large island below the upper left corner.

Total water vapor represents the depth of a layer if all the water vapor in the atmosphere were to condense and fall to the surface. The color bar on the right sides of the plots give the thickness of this layer in millimeters (mm). The first image, from August 28, shows typical tropical water vapor amounts over the ocean: between roughly 25 and 50 mm, or 1 to 2 inches. The highest values of roughly 80 mm, seen as a red blob over South America, corresponds to intense thunderstorms. Thunderstorms pull in water vapor from surrounding regions and concentrate it, with much of it then falling as rain.

Figure 1 shows total water during the passage of Hurricane Isabel on September 13. The storm is apparent: the ring of moderate values surrounding a very strong maximum of 100 mm. Total water of more than 80 mm is unusual, and these values correspond to the intense thunderstorms contained within Isabel. The thunderstorms--and the large values of total water--are fed by evaporation from the ocean in the hurricane's high winds. The water vapor near the center of the storm does not remain there long, since hurricane rain rates as high 50 mm (2 inches) per hour imply rapid cycling of the water we observe. Away from the storm the amount of total water vapor is rather low, associated with fair weather where air that ascended near the storm's eye returns to earth, having dropped its moisture as rain. Also seen in the second images are two small regions of about 70 mm of total water over south America. These are yet more thunderstorms, though likely much more benign than those in Isabel.

The Atmospheric Infrared Sounder Experiment, with its visible, infrared, and microwave detectors, provides a three-dimensional look at Earth's weather. Working in tandem, the three instruments can make simultaneous observations all the way down to the Earth's surface, even in the presence of heavy clouds. With more than 2,000 channels sensing different regions of the atmosphere, the system creates a global, 3-D map of atmospheric temperature and humidity and provides information on clouds, greenhouse gases, and many other atmospheric phenomena. The AIRS Infrared Sounder Experiment flies onboard NASA's Aqua spacecraft and is managed by NASA's Jet Propulsion Laboratory, Pasadena, Calif., under contract to NASA. JPL is a division of the California Institute of Technology in Pasadena.

2003-01-01

87

Mass spectrometry for water vapor measurements in the UT/LS  

NASA Astrophysics Data System (ADS)

Water vapor in the lower stratosphere plays a crucial role for the atmospheric radiation budget (Solomon et al., 2011). However, large uncertainties remain in measuring atmospheric water vapor mixing ratios below 10 ppmv typical for the lower stratosphere. To this end, we have developed the Atmospheric Ionization Mass Spectrometer (AIMS) for the accurate and fast detection of water vapor in the UT/LS from aircraft. In the AIMS instrument atmospheric air is directly ionized in a discharge ion source and the resulting water vapor clusters H3O+(H2O)n (n = 0..3) are detected with a linear quadrupole mass spectrometer as a direct measure of the atmospheric water vapor mixing ratio. AIMS is calibrated in-flight with a H2O calibration source using the catalytic reaction of H2 and O2 on a heated platinum surface to form gaseous H2O. This calibration setup combined with the water vapor mass spectrometry offers a powerful technical development in atmospheric hygrometry, enriching existing H2O measurement techniques by a new independent method. Here, we present AIMS water vapor measurements performed during the CONCERT2011 campaign (Contrail and Cirrus Experiment) with the DLR research aircraft Falcon. In September 2011 a deep stratospheric intrusion was probed over northern Europe with a dynamical tropopause lowered down to 6 km. We found sharp humidity gradients between tropospheric and stratospheric air at the edge of the tropopause fold, which we crossed 4 times at altitudes between 6 and 11 km. In the center of the tropopause fold, we measured water vapor mixing ratios down to 4 ppmv. The observed water vapor distribution is compared to water vapor analysis fields of the ECMWF's Integrated Forecast System (IFS) to evaluate the representation water vapor in this specific meteorological situation.

Kaufmann, S.; Voigt, C.; Schäuble, D.; Schäfler, A.; Schlager, H.; Thornberry, T. D.; Fahey, D. W.

2012-12-01

88

Deuterium fractionation between aqueous salt solutions and water vapor  

Microsoft Academic Search

The equilibrium fractionation factors for the partitioning of deuterium between pure water and water vapor at several temperatures (19°-27°C) and between aqueous salt solutions and water vapor as a function of salt concentration at 20°C are reported. The fractionation factors for the salt solutions show a linear variation with salt concentration and depend on the nature of both the cations

Michael K. Stewart; Irving Friedman

1975-01-01

89

Water Vapor Remote Sensing Techniques: Radiometry and Solar Spectrometry  

NASA Astrophysics Data System (ADS)

The high variability of atmospheric water vapor content plays an important role in space geodesy, climatology and meteorology. Water vapor has a strong influence on transatmospheric satellite signals, the Earth's climate and thus the weather forecasting. Several remote sensing techniques have been developed for the determination of inte- grated precipitable water vapor (IPWV). The Geodesy and Geodynamics Lab (GGL) utilizes the methods of Water Vapor Radiometry and Solar Spectrometry to quantify the amount of tropospheric water vapor and its temporal variations. The Water Vapor Radiometer (WVR) measures the radiation intensity of the atmosphere in a frequency band ranging from 20 to 32 GHz. The Solar Atmospheric MOnitoring Spectrome- ter (SAMOS) of GGL is designed for high-resolution measurements of water vapor absorption lines using solar radiation. In the framework of the ESCOMPTE (ExpÊrience sur Site pour COntraindre les Mod- Éles de Pollution atmosphÊrique et de Transport d'Emissions) field campaign these instruments have been operated near Marseille in 2001. They have aquired a long time series of integrated precipitable water vapor content (IPWV). The accuracy of IPWV measured by WVR and SAMOS is 1 kg/m2. Furthermore meteorological data from radiosondes were used to calculate the IPWV in order to provide comparisons with the results of WVR and SAMOS. The methods of Water Vapor Radiometry and So- lar Spectrometry will be discussed and first preliminary results retrieved from WVR, SAMOS and radiosondes during the ESCOMPTE field campaign will be presented.

Somieski, A.; Buerki, B.; Cocard, M.; Geiger, A.; Kahle, H.-G.

90

Measurement of atmospheric precipitable water using a solar radiometer. [water vapor absorption effects  

NASA Technical Reports Server (NTRS)

A technique is described and tested that allows the determination of atmospheric precipitable water from two measurements of solar intensity: one in a water-vapor absorption band and another in a nearby spectral region unaffected by water vapor.

Pitts, D. E.; Dillinger, A. E.; Mcallum, W. E.

1974-01-01

91

Advanced Water Vapor Lidar Detection System  

NASA Technical Reports Server (NTRS)

In the present water vapor lidar system, the detected signal is sent over long cables to a waveform digitizer in a CAMAC crate. This has the disadvantage of transmitting analog signals for a relatively long distance, which is subjected to pickup noise, leading to a decrease in the signal to noise ratio. Generally, errors in the measurement of water vapor with the DIAL method arise from both random and systematic sources. Systematic errors in DIAL measurements are caused by both atmospheric and instrumentation effects. The selection of the on-line alexandrite laser with a narrow linewidth, suitable intensity and high spectral purity, and its operation at the center of the water vapor lines, ensures minimum influence in the DIAL measurement that are caused by the laser spectral distribution and avoid system overloads. Random errors are caused by noise in the detected signal. Variability of the photon statistics in the lidar return signal, noise resulting from detector dark current, and noise in the background signal are the main sources of random error. This type of error can be minimized by maximizing the signal to noise ratio. The increase in the signal to noise ratio can be achieved by several ways. One way is to increase the laser pulse energy, by increasing its amplitude or the pulse repetition rate. Another way, is to use a detector system with higher quantum efficiency and lower noise, on the other hand, the selection of a narrow band optical filter that rejects most of the day background light and retains high optical efficiency is an important issue. Following acquisition of the lidar data, we minimize random errors in the DIAL measurement by averaging the data, but this will result in the reduction of the vertical and horizontal resolutions. Thus, a trade off is necessary to achieve a balance between the spatial resolution and the measurement precision. Therefore, the main goal of this research effort is to increase the signal to noise ratio by a factor of 10 over the current system, using a newly evaluated, very low noise avalanche photo diode detector and constructing a 10 MHz waveform digitizer which will replace the current CAMAC system.

Elsayed-Ali, Hani

1998-01-01

92

Water vapor column abundance retrievals during FIFE  

Microsoft Academic Search

This work is part of the First International Satellite Land Surface Climatology Project (ISLSCP) Field Experiment (FIFE), an international land-surface-atmosphere experiment aimed at improving the way climate models represent energy, water, heat, and carbon exchanges, and improving the utilization of satellite based remote sensing to monitor such parameters. The authors report on the use of a sunphotometer to extract column

C. J. Bruegge; J. E. Conel; R. O. Green; J. S. Margolis; R. G. Holm; G. Toon

1992-01-01

93

Effect of Increased Water Vapor Levels on TBC Lifetime  

SciTech Connect

To investigate the effect of increased water vapor levels on thermal barrier coating (TBC) lifetime, furnace cycle tests were performed at 1150 C in air with 10 vol.% water vapor (similar to natural gas combustion) and 90 vol.%. Either Pt diffusion or Pt-modified aluminide bond coatings were applied to specimens from the same batch of a commercial second-generation single-crystal superalloy and commercial vapor-deposited yttria-stabilized zirconia (YSZ) top coats were applied. Three coatings of each type were furnace cycled to failure to compare the average lifetimes obtained in dry O{sub 2}, using the same superalloy batch and coating types. Average lifetimes with Pt diffusion coatings were unaffected by the addition of water vapor. In contrast, the average lifetime of Pt-modified aluminide coatings was reduced by more than 50% with 10% water vapor but only slightly reduced by 90% water vapor. Based on roughness measurements from similar specimens without a YSZ coating, the addition of 10% water vapor increased the rate of coating roughening more than 90% water vapor. Qualitatively, the amount of {beta}-phase depletion in the coatings exposed in 10% water vapor did not appear to be accelerated.

Pint, Bruce A [ORNL; Garner, George Walter [ORNL; Lowe, Tracie M [ORNL; Haynes, James A [ORNL; Zhang, Ying [Tennessee Technological University

2011-01-01

94

Preliminary characterization of a water vaporizer for resistojet applications  

NASA Technical Reports Server (NTRS)

A series of tests was conducted to explore the characteristics of a water vaporizer intended for application to resistojet propulsion systems. The objectives of these tests were to (1) observe the effect of orientation with respect to gravity on vaporizer stability, (2) characterize vaporizer efficiency and outlet conditions over a range of flow rates, and (3) measure the thrust performance of a vaporizer/resistojet thruster assembly. A laboratory model of a forced-flow, once-through water vaporizer employing a porous heat exchange medium was built and characterized over a range of flow rates and power levels of interest for application to water resistojets. In a test during which the vaporizer was rotated about a horizontal axis normal to its own axis, the outlet temperature and mass flow rate through the vaporizer remained steady. Throttlability to 30 percent of the maximum flow rate tested was demonstrated. The measured thermal efficiency of the vaporizer was near 0.9 for all tests. The water vaporizer was integrated with an engineering model multipropellant resistojet. Performance of the vaporizer/thruster assembly was measured over a narrow range of operating conditions. The maximum specific impulse measured was 234 s at a mass flow rate and specific power level (vaporizer and thruster combined) of 154 x 10(exp-6)kg/s and 6.8 MJ/kg, respectively.

Morren, W. Earl

1992-01-01

95

COLUMN VAPOR EXTRACTION EXPERIMENTS ON GASOLINE CONTAMINATED SOIL  

EPA Science Inventory

Soil vapor extraction (SVE) is a technique that is used to remove volatile organic compounds from unsaturated soils. ir is pumped from the contaminated area and the chemicals are removed from the resulting vapor stream. n this work laboratory, soil column experiments were conduct...

96

Operating a radio-frequency plasma source on water vapor.  

PubMed

A magnetically enhanced radio-frequency (rf) plasma source operating on water vapor has an extensive list of potential applications. In this work, the use of a rf plasma source to dissociate water vapor for hydrogen production is investigated. This paper describes a rf plasma source operated on water vapor and characterizes its plasma properties using a Langmuir probe, a residual gas analyzer, and a spectrometer. The plasma source operated first on argon and then on water vapor at operating pressures just over 300 mtorr. Argon and water vapor plasma number densities differ significantly. In the electropositive argon plasma, quasineutrality requires n(i) approximately = n(e), where n(i) is the positive ion density. But in the electronegative water plasma, quasineutrality requires n(i+) = n(i-) + n(e). The positive ion density and electron density of the water vapor plasma are approximately one and two orders of magnitude lower, respectively, than those of argon plasma. These results suggest that attachment and dissociative attachment are present in electronegative water vapor plasma. The electron temperature for this water vapor plasma source is between 1.5 and 4 eV. Without an applied axial magnetic field, hydrogen production increases linearly with rf power. With an axial magnetic field, hydrogen production jumps to a maximum value at 500 W and then saturates with rf power. The presence of the applied axial magnetic field is therefore shown to enhance hydrogen production. PMID:19725651

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

2009-08-01

97

Operating a radio-frequency plasma source on water vapor  

SciTech Connect

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

Nguyen, Sonca V. T.; Gallimore, Alec D. [Plasmadynamics and Electric Propulsion Laboratory, University of Michigan, Ann Arbor, Michigan 48108 (United States); Foster, John E. [Plasma Science and Technology Laboratory, University of Michigan, Ann Arbor, Michigan 48108 (United States)

2009-08-15

98

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

NASA Technical Reports Server (NTRS)

Spectra taken by the Mars Global Surveyor Thermal Emission Spectrometer (TES) have been used to monitor the latitude, longitude, and seasonal dependence of water vapor for over one full Martian year (March 1999-March 2001). A maximum in water vapor abundance is observed at high latitudes during mid-summer in both hemispheres, reaching a maximum value of approximately 100 pr-micrometer in the north and approximately 50 pr-micrometer in the south. Low water vapor abundance (<5 pr-micrometer) is observed at middle and high latitudes in the fall and winter of both hemispheres. There are large differences in the hemispheric (north versus south) and seasonal (perihelion versus aphelion) behavior of water vapor. The latitudinal and seasonal dependence of the decay of the northern summer water vapor maximum implies cross-equatorial transport of water to the southern hemisphere, while there is little or no corresponding transport during the decay of the southern hemisphere summer maximum. The latitude-longitude dependence of annually-averaged water vapor (corrected for topography) has a significant positive correlation with albedo and significant negative correlations with thermal inertia and surface pressure. Comparison of TES results with those retrieved from the Viking Orbiter Mars Atmospheric Water Detectors (MAWD) experiments shows some similar features, but also many significant differences. The southern hemisphere maximum observed by TES was not observed by MAWD and the large latitudinal gradient in annually-averaged water vapor observed by MAWD does not appear in the TES results.

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

2001-01-01

99

Alteration of Apollo 17 orange fines by adsorbed water vapor  

Microsoft Academic Search

The changes in surface properties induced by adsorbed water vapor on Apollo 17 orange fines are evaluated and compared to those produced in soil samples from other locations, including an immediately adjacent Apollo 17 grey soil. Adsorbed water vapor changes the condition of each sample of fines from nonporous to porous. Particle size distributions show that the changes are internal

R. B. Gammage; H. F. Holmes

1976-01-01

100

Time domain measurement of the THz refractivity of water vapor  

E-print Network

Time domain measurement of the THz refractivity of water vapor Yihong Yang, Mahboubeh Mandehgar of the essentially frequency independent refractivity of water vapor from 0.1 to 1 THz, independent of the simultaneous strong THz pulse broadening and absorption. The humidity dependent transit time of THz pulses

Oklahoma State University

101

Detection of Thermal Water Vapor Emission from W Hydrae  

NASA Technical Reports Server (NTRS)

We have detected four far-infrared emission lines of water vapor toward the evolved star W Hydrae, using the Short Wavelength Spectrometer (SWS) of the Infrared Space Observatory (ISO). This is the first detection of thermal water vapor emission from a circumstellar outflow.

Neufeld, David A.; Chen, Wesley; Melnick, Gary J.; DeGraauw, Thijs; Feuchtgruber, Helmut; Harwitt, Martin

1997-01-01

102

CORRECTION FOR SCATTERING OPACITY OF MARTIAN ATMOSPHERIC WATER VAPOR ABUNDANCES  

E-print Network

CORRECTION FOR SCATTERING OPACITY OF MARTIAN ATMOSPHERIC WATER VAPOR ABUNDANCES Ann Sprague, Donald-based data of Barker (1976). Modeling of the phenomenon suggests that only water-vapor in the lowest 1000 m gray lines represent the corresponding surface pressures, computed from the topography. (We intend

Sprague, Ann L.

103

Extratropical Influence of Upper Tropospheric Water Vapor on Greenhouse Warming  

NASA Technical Reports Server (NTRS)

The purpose of this paper is to re-examine the impact of upper tropospheric water vapor on greenhouse warming in midlatitudes by analyzing the recent observations of the upper tropospheric water vapor from the Microwave Limb Sounder (MLS) on the Upper Atmosphere Research Satellite (UARS), in conjuction with other space-based measurement and model simulation products.

Hu, H.; Liu, W.

1998-01-01

104

SPARC Data Initiative: Comparison of water vapor climatologies from  

E-print Network

SPARC Data Initiative: Comparison of water vapor climatologies from international satellite limb,824�11,846, doi:10.1002/jgrd.50752, 2013 SPARC Data Initiative: Comparison of water vapor climatologies from series serve as basis for the "climatological" validation approach used within the project

Wirosoetisno, Djoko

105

Isotope variability in water vapor over Southern California  

NASA Astrophysics Data System (ADS)

Variations in the ratios of different isotopes of hydrogen and oxygen in water have long been used to trace water cycle processes, and the isotopic composition of water vapor in the atmosphere is known to change with weather events. Farlin et al. measured the isotopic composition of atmospheric water vapor in San Diego, Calif., at hourly intervals during February 2011 using a ground-based sensor. The time period included severe rainstorms and Santa Ana winds. They also used a general circulation model that included simulation of isotope variability to investigate how atmospheric and hydrologic processes affect isotope composition of water vapor near the surface.

Balcerak, Ernie

2013-07-01

106

Roles of Oxygen and Water Vapor in the Oxidation of Halogen Terminated Ge(111) Surfaces  

SciTech Connect

The initial stage of the oxidation of Cl and Br terminated Ge(111) surfaces is studied using photoelectron spectroscopy. The authors perform controlled experiments to differentiate the effects of different factors in oxidation, and find that water vapor and oxygen play different roles. Water vapor effectively replaces the halogen termination layers with the hydroxyl group, but does not oxidize the surfaces further. In contrast, little oxidation is observed for Cl and Br terminated surfaces with dry oxygen alone. However, with the help of water vapor, oxygen oxidizes the surface by breaking the Ge-Ge back bonds instead of changing the termination layer.

Sun, Shiyu; /Stanford U., Phys. Dept.; Sun, Yun; Liu, Zhi; Lee, Dong-Ick; Pianette, Piero; /SLAC, SSRL

2006-12-18

107

Warm Water Vapor around Sagittarius B2  

NASA Astrophysics Data System (ADS)

Several condensations heated externally by nearby hot stars are present in the Sgr B2 region for which H2O far-IR lines are expected to probe only an external low-density and high temperature section. Millimeter-wave lines can penetrate deeper into them (higher densities and lower Tk). We have conducted a study combining H2O lines in both spectral regions using the ISO (far-IR lines) and the IRAM 30 m telescope (183 GHz line). The far-IR H2O lines, seen in absorption, are optically thick. They form in the outermost gas in front of the far-IR continuum sources, probing a maximum visual extinction of ~5-10 mag. IR photons from the dust play a dominant role in their excitation. We conclude, based on observations of the CO J=7-6 line at 806.65 GHz, and the lack of emission from the far-IR CO lines, that the gas density has to be below ~104 cm-3. Using the gas kinetic temperature and density derived from OH, CO, and other molecular species, we derive a water column density of (9+/-3)×1016 cm-2 in the absorbing gas, implying an abundance of ~=(1-2)×10-5 in this region. The resulting relatively low H2O/OH abundance ratio, ~=2-4, is a signature of UV photon-dominated surface layers traced by far-IR observations. As a consequence, the temperature of the absorbing gas is high, Tk~=300-500 K, which allows very efficient neutral-neutral reactions producing H2O and OH. Finally, the 183.31 GHz data allow one to trace the inner, denser (n(H2)>=105-106 cm-3), and colder (Tk~40 K) gas. The emission is very strong toward the cores with an estimated water vapor abundance of a few × 10-7. There is also moderate extended emission around Sgr B2 main condensations, in agreement with the water vapor abundance derived from far-IR H2O lines. Based on observations with ISO, an ESA project with instruments funded by ESA Member States (especially the PI countries: France, Germany, the Netherlands, and the United Kingdom) and with participation of ISAS and NASA.

Cernicharo, José; Goicoechea, Javier R.; Pardo, Juan R.; Asensio-Ramos, Andrés

2006-05-01

108

LEO-LEO OCCULTATIONS MEASURING WATER VAPOR AND TEMPERATURE VIA ABSORPTION  

E-print Network

of water vapor at these altitudes. Utilizing the 22 GHz and the 183 GHz water vapor ab- sorption linesLEO-LEO OCCULTATIONS MEASURING WATER VAPOR AND TEMPERATURE VIA ABSORPTION S. Syndergaard, B. M of water vapor. Water vapor as well as dry air affects the refractivity of the atmosphere

109

Atmospheric water vapor absorption at 1.3 microm.  

PubMed

Absolute absorption cross sections for water vapor and water vapor/air mixtures were measured in a frequency range encompassing that of the chemically pumped atomic iodine laser. Measurements were made with a temperature-controlled multipass absorption cell and a high-resolution Fourier transform spectrometer. The measurements covered a broad range of water vapor and air pressures. Several techniques of data analysis were used, and the absorption cross section of 2 kPa of water vapor in an atmosphere of air was determined to be 1.1 +/- 0.2 x 10(-24) cm(2) . In this paper, an expression is derived which allows estimation of the absorption cross section for any pressure of water vapor and air. PMID:20454163

Bragg, S L; Kelley, J D

1987-02-01

110

Confirmation of Europa's water vapor plume activity  

NASA Astrophysics Data System (ADS)

STIS spectral UV images of Jupiter's satellite Europa obtained during HST Cycle 20 revealed atomic H and O auroral emissions in intensity ratios which uniquely identify the source as electron impact excitation of water molecules above Europa's south pole and hypothesized to be associated with water vapor plumes as reported in Roth et al., Science, 2014. The plumes were detected when Europa was at apocenter on December 30/31, 2012. Two other sets of STIS observations when Europa was near pericenter did not show plume emission within the sensitivity of STIS. The plume variability is predicted to be correlated with Europa's distance from Jupiter in the observed way. However, the one plume detection at apocenter and the two non-detections near pericenter require confirmation. Therefore we request two visits of 5 orbits each to observe Europa at orbital positions of the predicted maximum plume activity {similar to the December 2012 STIS Europa visit} to provide confirmation of the initial STIS discovery and to consolidate the predicted geophysical variability pattern.

Roth, Lorenz

2013-10-01

111

Temperature and water vapor pressure effects on the friction coefficient of hydrogenated diamondlike carbon films.  

SciTech Connect

Microtribological measurements of a hydrogenated diamondlike carbon film in controlled gaseous environments show that water vapor plays a significant role in the friction coefficient. These experiments reveal an initial high friction transient behavior that does not reoccur even after extended periods of exposure to low partial pressures of H{sub 2}O and O{sub 2}. Experiments varying both water vapor pressure and sample temperature show trends of a decreasing friction coefficient as a function of both the decreasing water vapor pressure and the increasing substrate temperature. Theses trends are examined with regard to first order gas-surface interactions. Model fits give activation energies on the order of 40 kJ/mol, which is consistent with water vapor desorption.

Dickrell, P. L.; Sawyer, W. G.; Eryilmaz, O. L.; Erdemir, A.; Energy Technology; Univ. of Florida

2009-07-01

112

ACA phase calibration scheme with the ALMA water vapor radiometers  

NASA Astrophysics Data System (ADS)

In Atacama Large Millimeter/submillimeter Array (ALMA) commissioning and science verification we have conducted a series of experiments of a novel phase calibration scheme for Atacama Compact Array (ACA). In this scheme water vapor radiometers (WVRs) devoted to measurements of tropospheric water vapor content are attached to ACA’s four total-power array (TP Array) antennas surrounding the 7 m dish interferometer array (7 m Array). The excess path length (EPL) due to the water vapor variations aloft is fitted to a simple two-dimensional slope using WVR measurements. Interferometric phase fluctuations for each baseline of the 7 m Array are obtained from differences of EPL inferred from the two-dimensional slope and subtracted from the interferometric phases. In the experiments we used nine ALMA 12-m antennas. Eight of them were closely located in a 70-m square region, forming a compact array like ACA. We supposed the most four outsiders to be the TP Array while the inner 4 antennas were supposed to be the 7 m Array, so that this phase correction scheme (planar-fit) was tested and compared with the WVR phase correction. We estimated residual root-mean-square (RMS) phases for 17- to 41-m baselines after the planar-fit phase correction, and found that this scheme reduces the RMS phase to a 70 - 90 % level. The planar-fit phase correction was proved to be promising for ACA, and how high or low PWV this scheme effectively works in ACA is an important item to be clarified.

Asaki, Yoshiharu; Matsushita, Satoki; Morita, Koh-Ichiro; Nikolic, Bojan

2012-09-01

113

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

Microsoft Academic Search

Building on previously published details of the laboratory calibrations of the Harvard Lyman-? photofragment fluorescence hygrometer (HWV) on the NASA ER-2 and WB-57 aircraft, we describe here the validation process for HWV, which includes laboratory calibrations and intercomparisons with other Harvard water vapor instruments at water vapor mixing ratios from 0 to 10 ppmv, followed by in-flight intercomparisons with the

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

2009-01-01

114

Validating AIRS upper atmosphere water vapor retrievals using aircraft and balloon in situ measurements  

Microsoft Academic Search

This paper provides an initial assessment of the accuracy of the Atmospheric Infrared Sounder (AIRS) water vapor retrievals from 500 to 100 mbar. AIRS satellite measurements are compared with accurate aircraft (NASA WB57) and balloon in situ water vapor measurements obtained during the NASA Pre-Aura Validation Experiment (Pre-AVE) in Costa Rica during Jan. 2004. AIRS retrieval (each pressure level of

D. E. Hagan; C. R. Webster; C. B. Farmer; R. D. May; R. L. Herman; E. M. Weinstock; L. E. Christensen; L. R. Lait; P. A. Newman

2004-01-01

115

Shock-induced vaporization of zinc -- Experiments and numerical simulations  

SciTech Connect

Prediction of the interaction between expanded vaporized debris and target materials for applications such as meteorite impact on space vehicles, ballistic penetration of armors, debris shield design, etc. demands an accurate treatment of the melting and vaporization process and the kinetics of liquid-vapor propagation. Historically, experimental efforts to understand high-pressure melting and vaporization have been hindered by unavailability of experimental launchers that are capable of speeds needed to induce vaporized states. Here, record-high impact speeds achieved using the Sandia HyperVelocity Launcher have permitted a systematic study of shock-induced full vaporization of zinc. Pressures up to 5.5 Mbar and temperatures as high as 39,000 K ({approximately} 3.4 eV) are induced in a thin zinc plate by impacting it with a tantalum flier at speeds up to 10.1 km/s. Such high pressures produce essentially full vaporization of the zinc because the thermodynamic release isentropes pass into the vapor dome near the critical point. To characterize vapor flow, the velocity history produced by stagnation of the zinc expansion products against a witness plate is measured with velocity interferometry. For each experiment, the time-resolved experimental interferometer record is compared with wavecode calculations using an analytical equation of state, called ANEOS, that is known to have performed quite well at lower impact speeds (less than {approximately} 7 km/s) where vaporization is negligible. Significant discrepancies between experiment and calculation are shown to exist under conditions of the more recent higher impact speeds in excess of 7 km/s where the release isentrope appears to pass near the critical point.

Chhabildas, L.C.; Brannon, R.M. [Sandia National Labs., Albuquerque, NM (United States). Ion Beam Generation Physics

1996-12-31

116

Factors Controlling Upper-Troposphere Water Vapor  

NASA Technical Reports Server (NTRS)

The seasonal changes of the upper-tropospheric humidity are studied with the water vapor data from the Microwave Limb Sounder on the National Aeronautics and Space Administration's Upper Atmosphere Research Satellite and the winds and vertical velocity data obtained from the European Centre for Medium-Range Weather Forecasts. Using the same algorithm for vertical transport as that used for horizontal transport (by Zhu and Newell), the authors find that the moisture in the tropical upper troposphere may be increased mainly by intensified local convection in a small portion, less than 10%, of the whole area between 40 degrees S and 40 degrees N. The contribution of large-scale background circulations and divergence of horizontal transport is relatively small in these regions. These dynamic processes cannot be revealed by the traditional analyses of moisture fluxes. The negative response suggested by Lindzen, with enhanced convection in the Tropics being accompanied by subsidence drying in the subtropics, also exists, but the latter does not apparently dominate in the moisture budget.

Zhu, Yong; Newell, Reginald E.; Read, William G.

2000-01-01

117

Water Vapor around Sgr B2  

E-print Network

We have conducted a study combining H2O lines in two spectral regions. First, Infrared Space Observatory observations of several H2O thermal lines seen in absorption toward Sgr B2(M) at a spectral resolution of 35 kms^-1 have been analyzed. Second, an IRAM-30m telescope map of the para-H2O 3_13-2_20 line at 183.31 GHz, seen in emission, has also been obtained and analyzed. The H2O lines seen in absorption are optically thick and are formed in the outermost gas of the condensations in front of the far-IR continuum sources. They probe a maximum visual extinction of ~5 to 10 mag. Radiative transfer models indicate that these lines are quite insensitive to temperature and gas density, and that IR photons from the dust play a dominant role in the excitation of the involved H2O rotational levels. The water vapor abundance in the region is (1-2)x10^-5. The relatively low H2O/OH abundance ratio in the region, 2-4, is a signature of UV photon dominated surface layers traced by far-IR observations.

J. Cernicharo; J. R. Goicoechea; J. R. Pardo; A. Asensio Ramos

2006-01-16

118

Processes Controlling Water Vapor in the Winter Arctic Stratospheric Middleworld  

NASA Technical Reports Server (NTRS)

Water vapor in the winter arctic stratospheric middleworld is import-an: for two reasons: (1) the arctic middleworld is a source of air for the upper Troposphere because of the generally downward motion, and thus its water vapor content helps determine upper tropospheric water, a critical part of the earth's radiation budget; and (2) under appropriate conditions, relative humidities will be large, even to the point of stratospheric cirrus cloud formation, leading to the production of active chlorine species that could destroy ozone. On a number of occasions during SOLVE, clouds were observed in the stratospheric middleworld by the DC-8 aircraft. These tended to coincide with regions of low temperatures, though some cases suggest water vapor enhancements due to troposphere-to-stratosphere transport. The goal of this work is to understand the importance of processes in and at the edge of the arctic stratospheric middleworld in determining water vapor at these levels. Specifically, is water vapor at these levels determined largely by the descent of air from above, or are clouds both within and at the edge of the stratospheric middleworld potentially important? How important is troposphere-to-stratosphere transport of air in determining stratospheric middleworld water vapor content? To this end, we will first examine the minimum saturation mixing ratios along theta/EPV tubes during the SOLVE winter and compare these with DC-8 water vapor observations. This will be a rough indicator of how high relative humidities can get, and the likelihood of cirrus cloud formation in various parts of the stratospheric middleworld. We will then examine saturation mixing ratios along both diabatic and adiabatic trajectories, comparing these values with actual aircraft water vapor observations, both in situ and remote. Finally, we will attempt to actually predict water vapor using minimum saturation mixing ratios along trajectories, cloud injection (derived from satellite imagery) along trajectories, and suitable initial conditions.

Pfister, Leonhard; Selkirk, Henry; Jensen, Eric; Sachse, Glenn; Podolske, James; Schoeberl, Mark; Browell, Edward; Ismail, Syed; Hipskind, R. Stephen (Technical Monitor)

2000-01-01

119

Monitoring the airborne dust and water vapor in the low atmosphere of Mars: the MEDUSA experiment for the ESA ExoMars mission  

NASA Astrophysics Data System (ADS)

Dust and water vapour are fundamental components of Martian atmosphere. Dust amount varies with seasons and with the presence of local and global dust storms, but never drops entirely to zero. Aerosol dust has always played a fundamental role on the Martian climate. Dust interaction with solar and thermal radiation and the related condensation and evaporation processes influence the thermal structure and balance, and the dynamics (in terms of circulation) of the atmosphere. Water vapour is a minor constituent of the Martian atmosphere but it plays a fundamental role and it is important as indicator of seasonal climate changes. Moreover, the interest about the water cycle on local and global scales is linked to the fundamental function that water could have played in relation to the existence of living organisms on Mars. In view of tracing the past environmental conditions on Mars, that possibly favoured the appearing of life forms, it is important to study the present climate and its evolution, on which dust and water vapour have (and have had) strong influence. Moreover, nowadays, dust is a relevant agent that affects environmental conditions in the lower Martian atmosphere and, thus, may interact / interfere with any instrumentation delivered to Mars surface for in situ analyses. So, information on dust properties and deposition rate is also of great interest for future mission design. Knowledge of how much dust settles on solar arrays and the size and shape of particles will be crucial elements for designing missions that will operate by solar power for periods of several years and will have moving parts which will experience degradation by dust. This information is essential also for proper planning of future manned missions in relation to characterisation of environmental hazardous conditions. Little is known about dust structure and dynamics, so far. Size distribution is known only roughly and the mechanism of settling and rising into the atmosphere, the rates and geographic variability are matter of controversy. The instrument MEDUSA (Martian Environmental DUst Systematic Analyser) has been designed to measure directly and quantitatively in situ the cumulative dust mass flux and dust deposition rate, the physical and electrification properties, the size distribution of intercepted particles and the water vapour abundance versus time, a goal that has never been reached so far. MEDUSA has been selected by ESA as one of the environmental instruments to be included in the payload Humboldt of ExoMars lander.

Esposito, Francesca; Colangeli, Luigi; Palumbo, Pasquale; Della Corte, Vincenzo; Molfese, Cesare; Merrison, Jonathan; Nornberg, Per; Lopez-Moreno, J. J.; Rodriguez Gomez, Julio

120

Climate and Ozone Response to Increased Stratospheric Water Vapor  

NASA Technical Reports Server (NTRS)

Stratospheric water vapor abundance affects ozone, surface climate, and stratospheric temperatures. From 30-50 km altitude, temperatures show global decreases of 3-6 K over recent decades. These may be a proxy for water vapor increases, as the Goddard Institute for Space Studies (GISS) climate model reproduces these trends only when stratospheric water vapor is allowed to increase. Observations suggest that stratospheric water vapor is indeed increasing, however, measurements are extremely limited in either spatial coverage or duration. The model results suggest that the observed changes may be part of a global, long-term trend. Furthermore, the required water vapor change is too large to be accounted for by increased production within the stratosphere, suggesting that ongoing climate change may be altering tropospheric input. The calculated stratospheric water vapor increase contributes an additional approximately equals 24% (approximately equals 0.2 W/m(exp 2)) to the global warming from well-mixed greenhouse gases over the past two decades. Observed ozone depletion is also better reproduced when destruction due to increased water vapor is included. If the trend continues, it could increase future global warming and impede stratospheric ozone recovery.

Shindell, Drew T.

2001-01-01

121

On the use of GPS tomography to investigate water vapor variability during a Mistral/sea breeze event in southeastern France  

E-print Network

1 On the use of GPS tomography to investigate water vapor variability during a Mistral/sea breeze (GPS) tomography analyses of water vapor, complemented by high resolution numerical simulations experiment. This is the first time GPS tomography has been used to validate the three-dimensional water vapor

Paris-Sud XI, Université de

122

Electron deposition in water vapor, with atmospheric applications.  

NASA Technical Reports Server (NTRS)

Examination of the consequences of electron impact on water vapor in terms of the microscopic details of excitation, dissociation, ionization, and combinations of these processes. Basic electron-impact cross-section data are assembled in many forms and are incorporated into semianalytic functions suitable for analysis with digital computers. Energy deposition in water vapor is discussed, and the energy loss function is presented, along with the 'electron volts per ion pair' and the efficiencies of energy loss in various processes. Several applications of electron and water-vapor interactions in the atmospheric sciences are considered, in particular, H2O comets, aurora and airglow, and lightning.

Olivero, J. J.; Stagat, R. W.; Green, A. E. S.

1972-01-01

123

Comparison of Upper Tropospheric Water Vapor from AIRS and Cryogenic Frostpoint Hygrometers  

NASA Technical Reports Server (NTRS)

Upper tropospheric water vapor (UTWV) from the Atmospheric Infrared Sounder (AIRS) experiment on NASA's Aqua spacecraft has the potential of addressing several important climate questions. The specified AIRS system measurement uncertainty for water vapor is 20 percent absolute averaged over 2 km layers. Cryogenic frostpoint hygrometers (CFH) are balloon-borne water vapor sensors responsive from the surface into the lower stratosphere. Several dozen coincident, collocated CFH profiles have been obtained for AlRS validation. The combination of CFH sensitivity and sample size offers a statistically compelling picture of AIRS UTWV measurement capability. We present a comparison between CFH observations and AlRS retrievals. We focus on the altitude range from the middle troposphere up to heights at the limits of AlRS sensitivity to water vapor, believed to be around 100-1 50 hPa.

Fetzer, Eric J.; Vomel, Holger

2004-01-01

124

Air-sea exchange of water vapor and sensible heat: The Humidity Exchange Over the Sea (HEXOS) results  

Microsoft Academic Search

Surface layer fluxes of sensible heat and water vapor were measured from a fixed-platform in the North Sea during the Humidity Exchange over the Sea (HEXOS) Main Experiment (HEXMAX). Eddy wind stress and other relevant atmospheric and oceanic parameters were measured simultaneously and are used to interpret the heat and water vapor flux results. One of the main goals of

J. DeCosmo; K. B. Katsaros; S. D. Smith; R. J. Anderson; W. A. Oost; K. Bumke; H. Chadwick

1996-01-01

125

Active Raman sounding of the earth's water vapor field  

NASA Technical Reports Server (NTRS)

The typically weak cross-sections characteristic of Raman processes has historically limited their use in atmospheric remote sensing to nighttime application. However, with advances in instrumentation and techniques, it is now possible to apply Raman lidar to the monitoring of atmospheric water vapor, aerosols and clouds throughout the diurnal cycle. Upper tropospheric and lower stratospheric measurements of water vapor using Raman lidar are also possible but are limited to nighttime and require long integration times. However, boundary layer studies of water vapor variability can now be performed with high temporal and spatial resolution. This paper will review the current state-of-the-art of Raman lidar for high-resolution measurements of the atmospheric water vapor, aerosol and cloud fields. In particular, we describe the use of Raman lidar for mapping the vertical distribution and variability of atmospheric water vapor, aerosols and clouds throughout the evolution of dynamic meteorological events. The ability of Raman lidar to detect and characterize water in the region of the tropopause and the importance of high-altitude water vapor for climate-related studies and meteorological satellite performance are discussed.

Tratt, David M.; Whiteman, David N.; Demoz, Belay B.; Farley, Robert W.; Wessel, John E.

2005-01-01

126

21 CFR 868.1975 - Water vapor analyzer.  

Code of Federal Regulations, 2010 CFR

...device intended to measure the concentration of water vapor in a patient's expired gases by using techniques such as mass spectrometry. (b) Classification. Class I (general controls). The device is exempt from the premarket...

2010-04-01

127

Numerical simulation of water injection into vapor-dominated reservoirs.  

National Technical Information Service (NTIS)

Water injection into vapor-dominated reservoirs is a means of condensate disposal, as well as a reservoir management tool for enhancing energy recovery and reservoir life. We review different approaches to modeling the complex fluid and heat flow processe...

K. Pruess

1995-01-01

128

Sensing atmospheric water vapor with the Global Positioning System  

Microsoft Academic Search

Global Positioning System (GPS) receivers, water vapor radiometers (WVRs), and surface meteorological equipment were operated at both ends of a 50-km baseline in Colorado to measure the precipitable water vapor (PWV) and wet delay in the line-of-sight to GPR satellites. Using high precision orbits, WVR-measured and GPS-inferred PWV differences between the two sites usually agreed to better than 1 mm.

Christian Rocken; Randolph Ware; Teresa Van Hove; Frederick Solheim; Chris Alber; James Johnson; Mike Bevis; Steven Businger

1993-01-01

129

DSN water vapor radiometer: Tropospheric range delay calibration  

NASA Technical Reports Server (NTRS)

A discussion is presented of the Deep Space Network water vapor radiometer by means of simultaneous antenna temperature and radiosonde measurements at Edwards Air Force Base. The calibration of radiometer gain and hot load radiometric noise temperature is also described. Calibration equations are given. It is found that with a selected data set, the RMS error is less than 1 cm over a total delay range of 9 to 38 cm. Limitations on the use of the water vapor radiometer are also given.

Slobin, S. D.; Batelaan, P. D.

1979-01-01

130

Stratospheric water vapor increases over the past half-century  

Microsoft Academic Search

Ten data sets covering the period 1954-2000 are analyzed to show a 1%\\/yr increase in stratospheric water vapor. The trend has persisted for at least 45 years, hence is unlikely the result of a single event, but rather indicative of long-term climate change. A long-term change in the transport of water vapor into the stratosphere is the most probable cause.

K. H. Rosenlof; E.-W. Chiou; W. P. Chu; D. G. Johnson; K. K. Kelly; H. A. Michelsen; G. E. Nedoluha; E. E. Remsberg; G. C. Toon; M. P. McCormick

2001-01-01

131

Water-vapor pressure control in a volume  

NASA Technical Reports Server (NTRS)

The variation with time of the partial pressure of water in a volume that has openings to the outside environment and includes vapor sources was evaluated as a function of the purging flow and its vapor content. Experimental tests to estimate the diffusion of ambient humidity through openings and to validate calculated results were included. The purging flows required to produce and maintain a certain humidity in shipping containers, storage rooms, and clean rooms can be estimated with the relationship developed here. These purging flows are necessary to prevent the contamination, degradation, and other effects of water vapor on the systems inside these volumes.

Scialdone, J. J.

1978-01-01

132

Logarithmic radiative effect of water vapor and spectral kernels  

NASA Astrophysics Data System (ADS)

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

Bani Shahabadi, Maziar; Huang, Yi

2014-05-01

133

Combined measurments of water vapor over Vipava Valley, Slovenia  

NASA Astrophysics Data System (ADS)

Water vapor is known as Earth's most abundant greenhouse gas and plays a critical role in hydrological cycles on all scales from climatologic to meteorological phenomena. Its concentration in the atmosphere can vary from barely traceable amounts to about 4%. The extent of water vapor contribution to global warming is still not completely understood and remains an important unresolved issue. A step towards better understanding of the role water vapor plays in atmospheric processes is real time temporal and spatial monitoring of its distribution. In 2012, we performed a dedicated monitoring campaign of water vapor and aerosol content in the atmosphere above the land-sea transition zone between Otlica Observatory and the Adriatic sea, where its distributions are expected to vary rapidly due to the changes in the wind direction and different effects of the heat flux on the sea and land surface. The monitoring was performed combining lidar, dual band GPS receiver and radiosonde measurements. Spatial distributions of aerosols and clouds in the investigated area was monitored using a long-range scanning Mie lidar. This contribution presents the details of the monitoring campaign. The comparison of Raman lidar and radiosonde mixing ratio profiles shows a good agreement between the two and the total water vapor content agrees well with the values obtained by GPS monitors. We also observed cases with strong correlation between distinct aerosol layers identified from Mie lidar scans and elevated water vapor concentration values at corresponding heights, which implies high aerosol hygroscopicity.

Stani?, Samo; Sušnik, Andreja; He, Tingyao; Gao, Fei; Bergant, Klemen; Veberi?, Darko

2013-04-01

134

Surface Science in the Richmond Lab: Vapor/Water Studies  

E-print Network

, and reactions of gaseous pollutants. These interactions are affected by organics at the water surface, as well interfacial water structure but have little affect on SO2(g) adsorption. Currently, we are investigating HClSurface Science in the Richmond Lab: Vapor/Water Studies Many of the Earth's important atmospheric

Richmond, Geraldine L.

135

Comparison of Water Vapor Sorption by Milk Powder Components  

Microsoft Academic Search

Water vapor is absorbed by milk powder at sites dependent upon the relative pres- sure, P\\/Po, of the atmosphere to which the powder is exposed. Comparison of the water sorption isotherms for the protein, sugar, and mixed salts comparable with that found in milk powder indicated that at low P\\/Po water is bound primarily by the casein fraction in the

B. A. Anderson; M. J. Pallansch

1968-01-01

136

Reversibility of Water Vapor Sorption by Cottage Cheese Whey Solids  

Microsoft Academic Search

Desorption isotherms for water vapor from cottage cheese whey so,lids vary with the way water is first sorbed by the whey solids. When water is sorbed progressively in small increments be- tween zero pressure and saturation pres- sure, the powder becomes 'more porous during lactose crystallization. Subsequent desorption data follow a sigmoid pattern as a function of relative pressure. More

B. A. Anderson

1975-01-01

137

CLIFF SWALLOW (PETROCHELIDON PYRRHONOTA) EGGS TO WATER VAPOR  

Microsoft Academic Search

The rate of diffusion of water molecules through air is inversely related to atmo- spheric pressure; diffusivit.v of water vapor, therefore, is greater at high altitudes than at low elevations. Assuming that conservation of water in avian eggs is essential for normal development and hatching of embryos, we predicted that eggs laid by birds nesting at high altitudes would have

PAUL R. SOTHERLAND; GARY C. PACKARD; THEODORE L. TAIGEN; THOMAS J. BOARDMAN

138

The threshold of vapor channel formation in water induced by pulsed CO2 laser  

NASA Astrophysics Data System (ADS)

Water plays an important role in laser ablation. There are two main interpretations of laser-water interaction: hydrokinetic effect and vapor phenomenon. The two explanations are reasonable in some way, but they can't explain the mechanism of laser-water interaction completely. In this study, the dynamic process of vapor channel formation induced by pulsed CO2 laser in static water layer was monitored by high-speed camera. The wavelength of pulsed CO2 laser is 10.64 um, and pulse repetition rate is 60 Hz. The laser power ranged from 1 to 7 W with a step of 0.5 W. The frame rate of high-speed camera used in the experiment was 80025 fps. Based on high-speed camera pictures, the dynamic process of vapor channel formation was examined, and the threshold of vapor channel formation, pulsation period, the volume, the maximum depth and corresponding width of vapor channel were determined. The results showed that the threshold of vapor channel formation was about 2.5 W. Moreover, pulsation period, the maximum depth and corresponding width of vapor channel increased with the increasing of the laser power.

Guo, Wenqing; Zhang, Xianzeng; Zhan, Zhenlin; Xie, Shusen

2012-12-01

139

Water Vapor-Mediated Volatilization of High-Temperature Materials  

NASA Astrophysics Data System (ADS)

Volatilization in water vapor-containing atmospheres is an important and often unexpected mechanism of degradation of high-temperature materials during processing and in service. Thermodynamic properties data sets for key (oxy)hydroxide vapor product species that are responsible for material transport and damage are often uncertain or unavailable. Estimation, quantum chemistry calculation, and measurement methods for thermodynamic properties of these species are reviewed, and data judged to be reliable are tabulated and referenced. Applications of water vapor-mediated volatilization include component and coating recession in turbine engines, oxidation/volatilization of ferritic steels in steam boilers, chromium poisoning in solid-oxide fuel cells, vanadium transport in hot corrosion and degradation of hydrocracking catalysts, Na loss from Na ?"-Al2O3 tubes, and environmental release of radioactive isotopes in a nuclear reactor accident or waste incineration. The significance of water vapor-mediated volatilization in these applications is described.

Meschter, Peter J.; Opila, Elizabeth J.; Jacobson, Nathan S.

2013-07-01

140

Balloon Borne Soundings of Water Vapor, Ozone and Temperature in the Upper Tropospheric and Lower Stratosphere as Part of the Second SAGE III Ozone Loss and Validation Experiment (SOLVE-2)  

NASA Technical Reports Server (NTRS)

The main goal of our work was to provide in situ water vapor and ozone profiles in the upper troposphere and lower stratosphere as reference measurements for the validation of SAGE III water vapor and ozone retrievals. We used the NOAA/CMDL frost point hygrometer and ECC ozone sondes on small research balloons to provide continuous profiles between the surface and the mid stratosphere. The NOAA/CMDL frost point hygrometer is currently the only lightweight balloon borne instrument capable of measuring water vapor between the lower troposphere and middle stratosphere. The validation measurements were based in the arctic region of Scandinavia for northern hemisphere observations and in New Zealand for southern hemisphere observations and timed to coincide with overpasses of the SAGE III instrument. In addition to SAGE III validation we also tried to coordinate launches with other instruments and studied dehydration and transport processes in the Arctic stratospheric vortex.

Voemel, Holger

2004-01-01

141

The vitiation effects of water vapor and carbon dioxide on the autoignition characteristics of kerosene  

NASA Astrophysics Data System (ADS)

In ground tests of hypersonic scramjet, the high-enthalpy airstream produced by burning hydrocarbon fuels often contains contaminants of water vapor and carbon dioxide. The contaminants may change the ignition characteristics of fuels between ground tests and real flights. In order to properly assess the influence of the contaminants on ignition characteristics of hydrocarbon fuels, the effect of water vapor and carbon dioxide on the ignition delay times of China RP-3 kerosene was studied behind reflected shock waves in a preheated shock tube. Experiments were conducted over a wider temperature range of 800-1 500K, at a pressure of 0.3 MPa, equivalence ratios of 0.5 and 1, and oxygen concentration of 20%. Ignition delay times were determined from the onset of the excited radical OH emission together with the pressure profile. Ignition delay times were measured for four cases: (1) clean gas, (2) gas vitiated with 10% and 20% water vapor in mole, (3) gas vitiated with 10% carbon dioxide in mole, and (4) gas vitiated with 10% water vapor and 10% carbon dioxide, 20% water vapor and 10% carbon dioxide in mole. The results show that carbon dioxide produces an inhibiting effect at temperatures below 1 300 K when ? = 0.5, whereas water vapor appears to accelerate the ignition process below a critical temperature of about 1 000 K when ? = 0.5. When both water vapor and carbon dioxide exist together, a minor inhibiting effect is observed at ? = 0.5, while no effect is found at ? = 1.0. The results are also discussed preliminary by considering both the combustion reaction mechanism and the thermophysics properties of the fuel mixtures. The current measurements demonstrate vitiation effects of water vapor and carbon dioxide on the autoignition characteristics of China RP-3 kerosene at air-like O2 concentration. It is important to account for such effects when data are extrapolated from ground testing to real flight conditions.

Liang, Jin-Hu; Wang, Su; Zhang, Sheng-Tao; Yue, Lian-Jie; Fan, Bing-Cheng; Zhang, Xin-Yu; Cui, Ji-Ping

2014-08-01

142

Visible and infrared spin scan radiometer atmospheric sounder water vapor and wind fields over Amazonia  

SciTech Connect

Both the mass and motion fields for Amazonia have been depicted using almost exclusively geostationary satellite data. Derived parameters include satellite retrievals of atmospheric temperature and dewpoint temperature, total precipitable water vapor, and cloud and water vapor winds. The capabilities of geostationary satellite data have been demonstrated at least four times a day for the period of May 5-8, 1987, during the Global Tropospheric Experiment/Amazon Boundary Layer Experiment. The satellite-derived information is able to resolve synoptic-scale atmospheric trends in space and time.

Schmit, T.J.; Brueske, K.F.; Smith, W.L. (Cooperative Institute for Meteorological Satellite Studies, Madison, WI (USA)); Menzel, W.P. (NOAA/National Environmental Satellite, Data, and Information Service, Madison, WI (USA))

1990-09-20

143

Enthalpy of Vaporization by Gas Chromatography: A Physical Chemistry Experiment  

ERIC Educational Resources Information Center

An experiment is conducted to measure the enthalpy of vaporization of volatile compounds like methylene chloride, carbon tetrachloride, and others by using gas chromatography. This physical property was measured using a very tiny quantity of sample revealing that it is possible to measure the enthalpies of two or more compounds at the same time.

Ellison, Herbert R.

2005-01-01

144

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

NASA Technical Reports Server (NTRS)

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

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

1987-01-01

145

Improved waste water vapor compression distillation technology. [for Spacelab  

NASA Technical Reports Server (NTRS)

The vapor compression distillation process is a method of recovering potable water from crewman urine in a manned spacecraft or space station. A description is presented of the research and development approach to the solution of the various problems encountered with previous vapor compression distillation units. The design solutions considered are incorporated in the preliminary design of a vapor compression distillation subsystem. The new design concepts are available for integration in the next generation of support systems and, particularly, the regenerative life support evaluation intended for project Spacelab.

Johnson, K. L.; Nuccio, P. P.; Reveley, W. F.

1977-01-01

146

Removal of Sarin Aerosol and Vapor by Water Sprays  

SciTech Connect

Falling water drops can collect particles and soluble or reactive vapor from the gas through which they fall. Rain is known to remove particles and vapors by the process of rainout. Water sprays can be used to remove radioactive aerosol from the atmosphere of a nuclear reactor containment building. There is a potential for water sprays to be used as a mitigation technique to remove chemical or bio- logical agents from the air. This paper is a quick-look at water spray removal. It is not definitive but rather provides a reasonable basic model for particle and gas removal and presents an example calcu- lation of sarin removal from a BART station. This work ~ a starting point and the results indicate that further modeling and exploration of additional mechanisms for particle and vapor removal may prove beneficial.

Brockmann, John E.

1998-09-01

147

Empirical water vapor continuum models for infrared propagation  

NASA Astrophysics Data System (ADS)

The characterization of the water vapor continuum remains an important problem concerning infrared propagation in the atmosphere. Radiometric imaging within the atmosphere in the 8 to 12 micrometers and 3 - 5 micrometers regions, and eye safe lidar in the 2 micrometers and 1.6 micrometers window regions require accurate knowledge of the water vapor continuum. Although the physical nature of the continuum is a complex problem, the observed frequency, pressure and temperature dependence can be represented reasonably well by simple mathematical functions consistent with far wing theories. This approach is the basis for current models used in LOWTRAN/MODTRAN and for the models listed in the SPIE/ERIM EO/IR Systems Handbook (Volume 2 Chapter 1). However, these models are based solely on a limited, but high quality, data set collected by a spectrometer and White cell. Additional information on oxygen broadening and temperature dependence is available from numerous laser measurements of the water vapor continuum. A survey of relevant experimental data is made to determine the best available measurements of the water vapor continuum in various atmospheric window regions. Then the data are fit to an empirical model over the entire window region. A good fit is obtained for typical atmospheric conditions covering the 8 to 12 micrometers and 3 to 5 micrometers regions. No experimental data, covering atmospheric conditions, exist in the 2 micrometers and 1.6 micrometers regions. However, models can be proposed based on far wing extrapolations of the bordering vibrational water vapor bands.

Thomas, Michael E.

1995-06-01

148

Adsorption of radon and water vapor on commercial activated carbons  

SciTech Connect

Equilibrium adsorption isotherms are reported for radon and water vapor on two commercial activated carbons: coconut shell Type PCB and hardwood Type BD. The isotherms of the water vapor were measured gravimetrically at 298 K. The isotherms of radon from dry nitrogen were obtained at 293, 298, and 308 K while the data for the mixture of radon and water vapor were measured at 298 K. The concentrations of radon in the gas and solid phases were measured simultaneously, once the adsorption equilibrium and the radioactive equilibrium between the radon and its daughter products were established. The shape of the isotherms was of Type III for the radon and Type V for the water vapor, according to Brunauer`s classification. The adsorption mechanism was similar for both the radon and the water vapor, being physical adsorption on the macropore surface area in the low pressure region and micropore filling near saturation pressure. The uptake capacity of radon decreased both with increasing temperature and relative humidity. The heat of adsorption data indicated that the PCB- and the BD-activated carbons provided a heterogeneous surface for radon adsorption. The equilibrium data for radon were correlated with a modified Freundlich equation.

Hassan, N.M. [Westinghouse Savannah River Co., Aiken, SC (United States); Ghosh, T.K.; Hines, A.L.; Loyalka, S.K. [Univ. of Missouri, Columbia, MO (United States)

1995-02-01

149

Design of Advanced Atmospheric Water Vapor Differential Absorption Lidar (DIAL) Detection System  

NASA Technical Reports Server (NTRS)

The measurement of atmospheric water vapor is very important for understanding the Earth's climate and water cycle. The lidar atmospheric sensing experiment (LASE) is an instrument designed and operated by the Langley Research Center for high precision water vapor measurements. The design details of a new water vapor lidar detection system that improves the measurement sensitivity of the LASE instrument by a factor of 10 are discussed. The new system consists of an advanced, very low noise, avalanche photodiode (APD) and a state-of-the-art signal processing circuit. The new low-power system is also compact and lightweight so that it would be suitable for space flight and unpiloted atmospheric vehicles (UAV) applications. The whole system is contained on one small printed circuit board (9 x 15 sq cm). The detection system is mounted at the focal plane of a lidar receiver telescope, and the digital output is read by a personal computer with a digital data acquisition card.

Refaat, Tamer F.; Luck, William S., Jr.; DeYoung, Russell J.

1999-01-01

150

Atmospheric Water Vapor during the 1998 La Nina (WMS)  

NSDL National Science Digital Library

Water vapor is a small but significant constituent of the atmosphere, warming the planet due to the greenhouse effect and condensing to form clouds which both warm and cool the Earth in different circumstances. A key feature of global atmospheric water vapor convection is the Intertropical Convergence Zone, the low pressure region within five degrees of the equator where the trade winds converge and solar heating of the atmosphere forces the water-laden air to rise in altitude, form clouds, and then precipitate as rain in the afternoon. This visualization shows the global water vapor distribution in gray and white and the global precipitation in yellow every hour from August 30, 1998 to September 20, 1998. The afternoon thunderstorms in the tropics are seen as a flashing yellow region that moves from east to west, following the sun. This is a La Nina period, when the water to the west of South America is cooler than normal, forcing the atmosphere there to cool down and hold less water. Strong east-to-west winds can be seen in this region, contributing to the high water vapor region that forms further to the west over southeast Asia, the Philippines, and Indonesia, causing increased humidity and rainfall in that region. This data is from the Goddard Earth Modeling System, a coupled land-ocean-atmosphere model which uses earth and satellite-based observations to simulate the Earths physical system during events such as La Nina.

Sokolowsky, Eric; Waldrop, John; Mitchell, Horace; Adamec, David

2004-02-12

151

Atmospheric Precorrected Differential Absorption technique to retrieve columnar water vapor  

SciTech Connect

Differential absorption techniques are suitable to retrieve the total column water vapor contents from imaging spectroscopy data. A technique called Atmospheric Precorrected Differential Absorption (APDA) is derived directly from simplified radiative transfer equations. It combines a partial atmospheric correction with a differential absorption technique. The atmospheric path radiance term is iteratively corrected during the retrieval of water vapor. This improves the results especially over low background albedos. The error of the method for various ground reflectance spectra is below 7% for most of the spectra. The channel combinations for two test cases are then defined, using a quantitative procedure, which is based on MODTRAN simulations and the image itself. An error analysis indicates that the influence of aerosols and channel calibration is minimal. The APDA technique is then applied to two AVIRIS images acquired in 1991 and 1995. The accuracy of the measured water vapor columns is within a range of {+-}5% compared to ground truth radiosonde data.

Schlaepfer, D.; Itten, K.I. [Univ. of Zuerich (Switzerland). Dept. of Geography] [Univ. of Zuerich (Switzerland). Dept. of Geography; Borel, C.C. [Los Alamos National Lab., NM (United States)] [Los Alamos National Lab., NM (United States); Keller, J. [Paul Scherrer Inst., Villigen (Switzerland)] [Paul Scherrer Inst., Villigen (Switzerland)

1998-09-01

152

Computation of infrared cooling rates in the water vapor bands  

NASA Technical Reports Server (NTRS)

A fast and accurate method is developed for calculating the infrared radiative terms due to water vapor - specifically, the atmospheric cooling rates. The accuracy is achieved by avoiding the constraints of band models and working directly with the absorption coefficient, which is a function of temperature and pressure as well as wavenumber. The method is based on calculation of an equivalent water vapor amount between atmospheric pressure levels and a table look-up procedure. Compared to line-by-line calculations, the present method has errors up to 4% of the maximum cooling rate. The use of a scaling factor, based on the far-wing approximation, limits the applicability of the method to the troposphere and lower stratosphere, where the line wings are responsible for most of the radiative cooling associated with water vapor.

Chou, M.-D.; Arking, A.

1980-01-01

153

Hydrogen isotope measurement corrections for low water vapor concentrations: Mauna Loa Observatory, Hawaii  

NASA Astrophysics Data System (ADS)

We present a comparison of laser spectroscopy measurements and traditional mass spectrometry techniques for measuring the hydrogen isotope composition of atmospheric water vapor. Laboratory experiments indicate that the Picarro gas analyzer has a negative relationship between inverse concentration and D/H ratio, so flask measurements were used to calibrate the laser spectroscopy systems at low water vapor concentrations and assess linearity. Field-based measurements made at the Mauna Loa Observatory (MLO) in Hawaii included data collection from both Picarro and Los Gatos Research laser analyzers and periodic sample collection in evacuated flasks for a period of 25 days. Air samples were collected in evacuated 2 L glass flasks and water vapor was separated from the non-condensable gases cryogenically. The remaining water was reduced to H2 gas and measured on an isotope ratio mass spectrometer. When the two laser systems are corrected to the flask data, they are strongly coincident over the entire 25 day sample period. Corrected ?D values ranged from -106‰ to -332‰. The ?D values of atmospheric water vapor changed by 200‰ within 2.5 minutes as the boundary layer elevation changed relative to MLO. This study demonstrates that field campaigns using laser analyzers in environments with low water vapor concentrations can be corrected to the international V-SMOW scale by calibration to the flask data measured conventionally. Bias correction is especially critical for accurate determination of deuterium excess in dry air.

Johnson, L. R.; Sharp, Z. D.; Galewsky, J.; Strong, M. H.; van Pelt, A. D.; Dong, F.; Noone, D. C.

2010-12-01

154

Investigation of water vapor motion winds from geostationary satellites  

NASA Technical Reports Server (NTRS)

Water vapor imagery from geostationary satellites has been available for over a decade. These data are used extensively by operational analysts and forecasters, mainly in a qualitative mode (Weldon and Holmes 1991). In addition to qualitative applications, motions deduced in animated water vapor imagery can be used to infer wind fields in cloudless regimes, thereby augmenting the information provided by cloud-drift wind vectors. Early attempts at quantifying the data by tracking features in water vapor imagery met with modest success (Stewart et al. 1985; Hayden and Stewart 1987). More recently, automated techniques have been developed and refined, and have resulted in upper-level wind observations comparable in quality to current operational cloud-tracked winds (Laurent 1993). In a recent study by Velden et al. (1993) it was demonstrated that wind sets derived from Meteosat-3 (M-3) water vapor imagery can provide important environmental wind information in data void areas surrounding tropical cyclones, and can positively impact objective track forecasts. M-3 was repositioned to 75W by the European Space Agency in 1992 in order to provide complete coverage of the Atlantic Ocean. Data from this satellite are being transmitted to the U.S. for operational use. Compared with the current GOES-7 (G-7) satellite (positioned near 112W), the M-3 water vapor channel contains a superior horizontal resolution (5 km vs. 16 km ). In this paper, we examine wind sets derived using automated procedures from both GOES-7 and Meteosat-3 full disk water vapor imagery in order to assess this data as a potentially important source of large-scale wind information. As part of a product demonstration wind sets were produced twice a day at CIMSS during a six-week period in March and April (1994). These data sets are assessed in terms of geographic coverage, statistical accuracy, and meteorological impact through preliminary results of numerical model forecast studies.

Velden, Christopher S.; Nieman, Steven J.; Wanzong, Steven

1994-01-01

155

Isobaric vapor-liquid equilibrium for ethanol + water + potassium nitrate  

SciTech Connect

An increasing research interest in the determination of the salt effect in the vapor-liquid equilibrium of binary systems has developed over the last few decades due to the importance of distillation with salts in the separation of close boiling and azeotropic mixtures. Isobaric vapor-liquid equilibrium for ethanol (1) + water (2) + potassium nitrate (3) at various concentrations of salt and with ethanol mole fractions from 0 to 0.642 has been measured at 100.0 kPa. The results were correlated by assuming that the salt was in ionic form and it was associated only with the water.

Vercher, E.; Pena, M.P.; Martinez-Andreu, A. [Univ. de Valencia (Spain). Dept. de Ingenieria Quimica] [Univ. de Valencia (Spain). Dept. de Ingenieria Quimica

1996-01-01

156

Isobaric vapor-liquid equilibrium for ethanol + water + strontium nitrate  

SciTech Connect

The effect of salts on the vapor-liquid equilibrium of solvent mixtures is of considerable interest in the separation of close boiling and azeotropic mixtures. The salt effect has been studied by many researchers. Most investigations have been limited to measurements on the saturated salt solutions. Isobaric vapor-liquid equilibrium for ethanol (1) + water (2) + strontium nitrate (3) at various concentrations of salt and with ethanol mole fractions from 0 to 0.672, has been measured at 100.0 kPa. The results were correlated by assuming that the salt was in ionic form and it was associated only with the water.

Vercher, E.; Pena, M.P.; Martinez-Andreu, A. [Univ. de Valencia (Spain)] [Univ. de Valencia (Spain)

1996-07-01

157

Airborne differential absorption lidar system for water vapor investigations  

NASA Technical Reports Server (NTRS)

Range-resolved water vapor measurements using the differential-absorption lidar (DIAL) technique is described in detail. The system uses two independently tunable optically pumped lasers operating in the near infrared with laser pulses of less than 100 microseconds separation, to minimize concentration errors caused by atmospheric scattering. Water vapor concentration profiles are calculated for each measurement by a minicomputer, in real time. The work is needed in the study of atmospheric motion and thermodynamics as well as in forestry and agriculture problems.

Browell, E. V.; Carter, A. F.; Wilkerson, T. D.

1981-01-01

158

Moisture burst structure in satellite water vapor imagery  

E-print Network

Subject: Meteorology MOISTURE BURST STRUCTURE IN SATELLITE WATER VAPOR IMAGERT A Thesis by DAVID JOEL ULSH Approved as to style and content by: James P. McGuzr)r (Co-Cha' an Aylrner H. Thompson (Co-Chairman) K th L. Whit (Member) James R. Sc... ins (Head of Department) May 1988 ABSTRACT Moisture Burst Structure in Satellite Water Vapor Imagery. (May 19BS) David Joel Ulsh, B. S. , Montana State University Co-Chairmen of Advisory Committee: Dr. James P. McGuirk Dr. Aylmer H. Thompson...

Ulsh, David Joel

2012-06-07

159

Infrared and millimeter-wavelength absorption by atmospheric water vapor  

NASA Astrophysics Data System (ADS)

An account is given of the current understanding of the atmospheric water vapor window regions from 10 to 1000 GHz, 8-12 microns, and 2-2.5 microns, with attention to the continuum absorption observable in each window region. The observed frequency-dependence in each window is consistent with the concept of far wings that emanate from the bordering water vapor absorption bands; this connection is considered the most prominent basis for the modeling of continuum absorption. It is judged that absorption behavior beyond experimentally measured conditions can be predicted with reasonable confidence.

Thomas, Michael E.

1987-12-01

160

Stability of Materials in High Temperature Water Vapor: SOFC Applications  

NASA Technical Reports Server (NTRS)

Solid oxide fuel cell material systems require long term stability in environments containing high-temperature water vapor. Many materials in fuel cell systems react with high-temperature water vapor to form volatile hydroxides which can degrade cell performance. In this paper, experimental methods to characterize these volatility reactions including the transpiration technique, thermogravimetric analysis, and high pressure mass spectrometry are reviewed. Experimentally determined data for chromia, silica, and alumina volatility are presented. In addition, data from the literature for the stability of other materials important in fuel cell systems are reviewed. Finally, methods for predicting material recession due to volatilization reactions are described.

Opila, E. J.; Jacobson, N. S.

2010-01-01

161

Frequency selection and calibration of a water vapor radiometer  

NASA Technical Reports Server (NTRS)

The calibration coefficients of existing water vapor radiometers are dependent upon meteorology profiles. This is shown to be due mainly to incorrect frequency pairs. By properly selecting an optimum frequency pair, the dependency can be reduced to a relatively small amount which can be handily adjusted by surface measurement alone. Hence, a universal calibration equation is applicable to all environmental conditions - site, seasonal and diurnal variations. Optimum frequency pairs are systematically searched. Error analysis indicates that calibration for the water vapor phase delay accurate to less than 2 cm is possible at all elevation angles greater than 15 degrees.

Wu, S. C.

1978-01-01

162

A GCM Study of Volcanic Eruptions as a Cause of Increased Stratospheric Water Vapor  

Microsoft Academic Search

Recent general circulation model (GCM) experiments have shown that idealized climatic perturbations that increase the temperature of the tropical tropopause region can cause larger than expected surface temperature increases. This is because the extra water vapor that is transported into the stratosphere acts as a positive radiative forcing agent. Since major volcanic eruptions in the Tropics also perturb temperatures in

Manoj M. Joshi; Keith P. Shine

2003-01-01

163

Investigating Vaporization of Silica through Laser Driven Shock Wave Experiments  

NASA Astrophysics Data System (ADS)

Giant impacts melt and vaporize a significant amount of the bolide and target body. However, our ability to determine how much melt or vapor a given impact creates depends strongly on our understanding of the liquid-vapor phase boundary of geologic materials. Our current knowledge of the liquid-vapor equilibrium for one of the most important minerals, SiO2, is rather limited due to the difficulty of performing experiments in this area of phase space. In this study, we investigate the liquid-vapor coexistence region by shocking quartz into a supercritical fluid state and allowing it to adiabatically expand to a state on the liquid-vapor phase boundary. Although shock compression and release has been used to study the liquid-vapor equilibrium of metals [1], few attempts have been made at studying geologic materials by this method [2]. Shock waves were produced by direct ablation of the quartz sample using the Jupiter Laser Facility of Lawrence Livermore National Laboratory. Steady shock pressures of 120-360 GPa were produced in the quartz samples: high enough to force the quartz into a supercritical fluid state. As the shock wave propagates through the sample, we measure the shock velocity using a line imaging velocity interferometer system for any reflector (VISAR) and shock temperature using a streaked optical pyrometer (SOP). When the shock wave reaches the free surface of the sample, the material adiabatically expands. Upon breakout of the shock at the free surface, the SOP records a distinct drop in radiance due to the lower temperature of the expanded material. For a subset of experiments, a LiF window is positioned downrange of the expanding silica. When the expanding silica impacts the LiF window, the velocity at the interface between the expanding silica and LiF window is measured using the VISAR. From the shock velocity measurements, we accurately determine the shocked state in the quartz. The post-shock radiance measurements are used to constrain the temperature on the liquid-vapor phase boundary (e.g., [3]) at much higher pressures than previously possible using a 2 stage gas gun [4, 5]. The density on the liquid-vapor phase boundary is constrained by comparing the velocity at the silica-LiF interface to numerical simulations that use equations of state with systematically varied liquid-vapor phase boundaries. We present the results within the context of understanding vaporization during giant impact events. [1] Brannon, R.M. and L.C. Chhabildas (1995) Int. J. Impact Engng. 17, 109-120. [2] Kurosawa, K. and S. Sugita (2010) J. Geophys. Res. in press. [3] Stewart, S.T., A. Seifter, and A.W. Obst (2008) Geophys. Res. Lett., 35, (23). [4] Lyzenga, G.A., T.J. Ahrens, and A.C. Mitchell (1983) J. Geophys. Res. , 88, (NB3), 2431-2444. [5] Boslough, M.B. (1988) J. Geophys. Res., 93, (B6), 6477-6484.

Kraus, R. G.; Swift, D. C.; Stewart, S. T.; Smith, R.; Bolme, C. A.; Spaulding, D. K.; Hicks, D.; Eggert, J.; Collins, G.

2010-12-01

164

The Nimbus 7 LIMS (Limb Infrared Monitor of the Stratosphere) water vapor measurements  

NASA Technical Reports Server (NTRS)

Earth orbital instruments, designed to measure the vertical and spatial distribution of atmospheric water vapor is discussed. Specifically, the operation of the Limb Infrared Monitor of the Stratosphere (LIMS) experiment is examined. The LIMS is a six channel limb scanning radiometer that was launched aboard Nimbus 7 in 1978. Profiles of stratospheric and mesospheric temperature, water vapor, and various other constituents were obtained by inverting the LIMS radiance measurements. This same technique was used in 1981 to analyze the data returned from another limb scanning radiometer aboard the Solar Mesosphere Explorer.

Remsberg, Ellis E.; Russell, James M., III

1988-01-01

165

Compact airborne Raman lidar for profiling aerosol, water vapor and clouds.  

PubMed

A compact airborne Raman lidar system, which can perform water vapor and aerosol measurements both during nighttime and daytime is described. The system design, setup and the data processing methods are described in the paper. The Raman lidar was tested on University of Wyoming King Air research aircraft (UWKA) during the Wyoming King Air PBL Exploratory Experiment (KAPEE) in 2010. An observation showing clouds, aerosols and a dry line is presented to illustrate the lidar detection capabilities. Comparisons of the water vapor and aerosol measurements using the Raman lidar and other in situ airborne instruments show good agreement. PMID:25321266

Liu, Bo; Wang, Zhien; Cai, Yong; Wechsler, Perry; Kuestner, William; Burkhart, Matthew; Welch, Wayne

2014-08-25

166

Toward an operational water vapor remote sensing system using the global positioning system  

SciTech Connect

Water vapor is one of the most important constituents of the free atmosphere since it is the principal mechanism by which moisture and latent heat are transported and cause weather. Recent experiments have demonstrated that data from Global Positioning System (GPS) satellites can be used to monitor precipitable water vapor (PWV) with millimeter accuracy and sub-hourly temporal resolution. Major advantages of GPS-based systems include the following: they work under virtually all weather conditions; individual systems do not have to be calibrated; and, they are relatively inexpensive.

Gutman, S.I.; Chadwick, R.B.; Wolf, d.W. [National Oceanic and Atmospheric Administration, Boulder, CO (United States); Simon, A. [Cooperative Institute for Research in Environmental Science, Boulder, CO (United States); Van Hove, T.; Rocken, C. [Univ. of Navstar Consortium, Boulder, CO (United States)

1995-04-01

167

[Study on large-scale regional laser detection methods for water vapor concentration].  

PubMed

Water vapor is an important meteorological parameter in the atmosphere, TDLAS direct absorption technology combined with open-path monitoring was used in order to achieve large-scale regional atmospheric water vapor concentration detection with high sensitivity, high accuracy and fast response, and to correct the remote sensing data. The large-scale regional laser detection system for water vapor was designed and the absorption line of water vapor molecules near 1.27 microm was chosen as the goal line. The system performance was verified in conjunction with a multiple reflection cell, that the system limit sensitivity was 14.803 mmol.mol-1 in optical path of 40 m. The continuous field experiment in 1,420 m optical path at the Yucheng Integrated Experimental Station, CAS was completed with this system which worked stably. Then the measured data was compared with the data of a gas analyzer LI-7500 in eddy correlation observation system at the same site, and the data consistency was good. A new method for water vapor concentration monitoring in the complex field of non-uniform underlying surface was provided. PMID:23705417

He, Ying; Zhang, Yu-Jun; Wang, Li-Ming; You, Kun; Zhou, Yi; Sun, Xiao-Min; Liu, Zhen-Min

2013-03-01

168

Water vapor spectroscopy in the 815-nm wavelength region for Differential Absorption Lidar measurements  

NASA Technical Reports Server (NTRS)

The differential absorption lidar (DIAL) technique was first applied to the remote measurement of atmospheric water vapor profiles from airborne platforms in 1981. The successful interpretation of the lidar profiles relies strongly on an accurate knowledge of specific water vapor absorption line parameters: line strength, pressure broadening coefficient, pressure-induced shift coefficient and the respective temperature-dependence factors. NASA Langley Research Center has developed and is currently testing an autonomous airborne water vapor lidar system: LASE (Lidar Atmospheric Sensing Experiment). This DIAL system uses a Nd:YAG-pumped Ti:Sapphire laser seeded by a diode laser as a lidar transmitter. The tunable diode has been selected to operate in the 813-818 nm wavelength region. This 5-nm spectral interval offers a large distribution of strengths for temperature-insensitive water vapor absorption lines. In support of the LASE project, a series of spectroscopic measurements were conducted for the 16 absorption lines that have been identified for use in the LASE measurements. Prior to this work, the experimental data for this water vapor absorption band were limited - to our knowledge - to the line strengths and to the line positions.

Ponsardin, Patrick; Browell, Edward V.

1995-01-01

169

Dual-beam wavelength modulation spectroscopy for sensitive detection of water vapor  

NASA Astrophysics Data System (ADS)

A technique was reported for sensitive detection of water vapor based on dual-beam wavelength modulation spectroscopy (WMS). Particular attention was focused on the problem of laser power variation (LPV) and residual amplitude modulation (RAM), which accounted for the absorption profile's distortion during application of WMS. Impact from LPV and RAM was eliminated by photocurrent normalization through a balanced ratiometric detector, which was a dual-beam technique with shot noise-level performance. When consideration of distortion was required, this could enormously simplify the spectra analysis procedure. In the experiment symmetry of the WMS, profile had gotten an improvement by a factor of about 102 compared with traditional single-beam method. During the application test of water vapor detection, the detected amplitude of WMS was well proportional to water vapor concentration ranging from 25 to 1,048 ppmv and the sensitivity was achieved to be 52 ppbv for just a 10-cm optical path length.

Wang, Qiang; Chang, Jun; Wei, Wei; Zhu, Cunguang; Tian, Changbin

2014-09-01

170

Water vapor profiling using a widely tunable amplified diode laser Differential Absorption Lidar (DIAL)  

NASA Astrophysics Data System (ADS)

Water vapor is one of the most significant constituents of the atmosphere because of its role in cloud formation, precipitation, and interactions with electromagnetic radiation, especially its absorption of longwave infrared radiation. Some details of the role of water vapor and related feedback mechanisms in the Earth system need to be characterized better if local weather, global climate, and the water cycle are to be understood. Water vapor profiles are currently obtained with several remote sensing techniques, such as microwave radiometers, passive instruments like the Atmospheric Emitted Radiance Interferometer (AERI) and Atmospheric Infrared Sounder (AIRS), and Raman lidar. Each of these instruments has some disadvantage, such as only producing column-integrated water vapor amounts or being large, overly customized, and costly, making them difficult to use for deployment in networks or onboard satellites to measure water vapor profiles. This thesis work involved the design, construction, and testing of a highly-tunable Differential Absorption Lidar (DIAL) instrument utilizing an all-semiconductor transmitter. It was an attempt to take advantage of semiconductor laser technology to obtain range-resolved water vapor profiles with an instrument that is cheaper, smaller, and more robust than existing field instruments. The eventual goal of this project was to demonstrate the feasibility of this DIAL instrument as a candidate for deployment in multi-point networks or satellite arrays to study water vapor flux profiles. This new DIAL instrument transmitter has, for the first time in any known DIAL instrument, a highly-tunable External Cavity Diode Laser (ECDL) as a seed laser source for two cascaded commercial tapered amplifiers. The transmitter has the capability of tuning over a range of ˜17 nm to selectively probe several available water vapor absorption lines, depending on current environmental conditions. This capability has been called for in other recent DIAL experiments. Tests of the DIAL instrument to prove the validity of its measurements are presented. Initial water vapor profiles, taken in the Bozeman, MT, area, were taken, analyzed, and compared with co-located radiosonde measurements. Future improvements and directions for the next generation of this DIAL instrument are discussed.

Obland, Michael Drew

171

The Use of Additional GPS Frequencies to Independently Determine Tropospheric Water Vapor Profiles  

NASA Technical Reports Server (NTRS)

It is well known that the currently employed L1 and L2 GPS/MET frequencies (1.2 - 1.6) Ghz) do not allow for the separation of water vapor and density (or temperature) from active microwave occultation measurements in regions of the troposphere warmer than 240 K Therefore, additional information must be used, from other types of measurements and weather analyses, to recover water vapor (and temperature) profiles. Thus in data sparse regions, these inferred profiles can be subject to larger errors than would result in data rich regions. The use of properly selected additional GPS frequencies enables a direct, independent measurement of the absorption associated with the water vapor profile, which may then be used in the standard GPS/MET retrievals to obtain a more accurate determination of atmospheric temperature throughout the water vapor layer. This study looks at the use of microwave crosslinks in the region of the 22 Ghz water vapor absorption line for this purpose. An added advantage of using 22 Ghz frequencies is that they are only negligibly affected by the ionosphere in contrast to the large effect at the GPS frequencies. The retrieval algorithm uses both amplitude and phase measurements to obtain profiles of atmospheric pressure, temperature and water water vapor pressure with a vertical resolution of 1 km or better. This technique also provides the cloud liquid water content along the ray path, which is in itself an important element in climate monitoring. Advantages of this method include the ability to make measurements in the presence of clouds and the use of techniques and technology proven through the GPS/MET experiment and several of NASA's planetary exploration missions. Simulations demonstrating this method will be presented for both clear and cloudy sky conditions.

Herman, B.M.; Feng, D.; Flittner, D. E.; Kursinski, E. R.

2000-01-01

172

Water vapor and carbon dioxide species measurements in narrow channels  

Microsoft Academic Search

Classical spectroscopic techniques have been applied in a novel manner to measure the concentration of gas species, water vapor and carbon dioxide, within a narrow channel flow field non-invasively. Tunable diode laser absorption spectroscopy (TDLAS) was used in conjunction with a laser modulated at a high frequency [Wavelength Modulation Spectroscopy (WMS)] tuned to the ro-vibrational transition of the species. This

Saptarshi Basu; Derek E. Lambe; Ranganathan Kumar

2010-01-01

173

DETERMINING HOW VAPOR PHASE MTBE REACHES GROUND WATER  

EPA Science Inventory

EPA Region 2 and ORD have funded a RARE project for FY 2005/2006 to evaluate the prospects that MTBE (and other fuel components) in vapors that escape from an underground storage tank (UST) can find its way to ground water produced by monitoring wells at a gasoline filling statio...

174

No alarming ozone loss from stratospheric water vapor  

NASA Astrophysics Data System (ADS)

At sufficiently low temperatures, water vapor in the lowermost stratosphere can cause ambient sulfate aerosol to grow, providing surfaces on which chlorine can activate to a form that destroys ozone. Ozone depletion in the stratosphere can allow harmful ultraviolet radiation to reach Earth's surface.

Balcerak, Ernie

2013-08-01

175

Mesospheric water vapor measured with an airborne sensor  

NASA Astrophysics Data System (ADS)

Mesospheric water vapor distribution was measured between 30 and 80 km, using an airborne 183 GHz sensor. Data analysis shows typical volume mixing ratios below 3 ppm above 50 km with no significant maximum at the stratopause as found with ground based 22 GHz measurements.

Hartmann, G. K.; Kuenzi, K. F.; Lobsiger, E.

1983-04-01

176

Can we modify stratospheric water vapor by deliberate cloud seeding?  

NASA Astrophysics Data System (ADS)

water vapor has an important effect on Earth's climate. Considering the significance of overshooting deep convection in modulating the water vapor content (WVC) of the lower stratosphere (LS), we use a three-dimensional convective cloud model to simulate the effects of various silver iodide (AgI) seeding scenarios on tropical overshooting deep convection that occurred on 30 November 2005 in Darwin, Australia. The primary motivation for this study is to investigate whether the WVC in the LS can be artificially modified by deliberate cloud seeding. It is found that AgI seeding done at the early stages of clouds produces significant effects on cloud microphysical and dynamical properties, and that further affects the WVC in the LS, while seeding at the mature stages of clouds has only a slight impact. The response of stratospheric water vapor to changes in the amount of seeding agent is nonlinear. The seeding with a small (large) amount of AgI increases (decreases) the WVC in the LS, due to enhanced (reduced) production and vertical transport of cloud ice from the troposphere and subsequent sublimation in the stratosphere. The results show that stratospheric water vapor can be artificially altered by deliberate cloud seeding with proper amount of seeding agent. This study also shows an important role of graupel in regulating cloud microphysics and dynamics and in modifying the WVC in the LS.

Chen, Baojun; Yin, Yan

2014-02-01

177

Advances in Raman Lidar Measurements of Water Vapor  

NASA Technical Reports Server (NTRS)

Recent technology upgrades to the NASA/GSFC Scanning Raman Lidar have permitted significant improvements in the daytime and nighttime measurement of water vapor using Raman lidar. Numerical simulation has been used to study the temperature sensitivity of the narrow spectral band measurements presented here.

Whiteman, D. N.; Evans, K.; Demoz, B.; DiGirolamo, P.; Mielke, B.; Stein, B.; Goldsmith, J. E. M.; Tooman, T.; Turner, D.; Starr, David OC. (Technical Monitor)

2002-01-01

178

A SEARCH FOR WATER VAPORIZATION ON CERES  

SciTech Connect

There are hints that the dwarf planet (1) Ceres may contain a large amount of water ice. Some models and previous observations suggest that ice could be close enough to the surface to create a flux of water outward through the regolith. This work aims to confirm a previous detection of OH emission off the northern limb of Ceres with the International Ultraviolet Explorer (IUE). Such emission would be evidence of water molecules escaping from the dwarf planet. We used the Ultraviolet and Visual Echelle Spectrograph of the Very Large Telescope to obtain spectra off the northern and southern limbs of Ceres at several epochs. These spectra cover the 307-312 nm wavelength range corresponding to the OH (0,0) emission band, which is the brightest band of this radical, well known in the cometary spectra. These new observations, five times more sensitive than those from IUE, did not permit detection of OH around Ceres. We derive an upper limit for the water production of about {approx}7 x 10{sup 25} molecules s{sup -1} and estimate the minimum thickness of the dust surface layer above the water ice layer (if present) to be about 20 m.

Rousselot, P.; Mousis, O.; Zucconi, J.-M. [Observatoire de Besancon, Institut UTINAM-UMR CNRS 6213, University of Franche-Comte, BP 1615, 25010 Besancon Cedex (France); Jehin, E.; Manfroid, J. [Institut d'Astrophysique et de Geophysique, Universite de Liege, Allee du 6 aout 17, B-4000 Liege (Belgium); Dumas, C. [European Southern Observatory, Alonso de Cordova 3107, Vitacura, Casilla 19001, Santiago 19 (Chile); Carry, B. [European Space Astronomy Centre, ESA, P.O. Box 78, 28691 Villanueva de la Canada, Madrid (Spain); Marboeuf, U., E-mail: rousselot@obs-besancon.fr [Institut de Planetologie et d'Astrophysique de Grenoble, Universite Joseph Fourier, CNRS INSU (France)

2011-10-15

179

a Study of Gnss Water Vapor Reconstruction Parameters  

NASA Astrophysics Data System (ADS)

GNSS (Global Navigation Satellite Systems) observations are nowadays a well-established tool to measure the water vapor content in the atmosphere. This gas plays a major role in many processes concerning physics, thermodynamics and dynamics of the atmosphere. The knowledge of the spatial and temporal distribution of water vapor in the lower atmosphere (troposphere) is crucial for accurate quantitative prediction of precipitation and better understanding of many atmospheric processes like deep convective events. Major advantages of the use of GNSS observations are all-weather system, continuous unattended operation, high temporal resolution and an ever-increasing number of stations. The present work focuses on the study of the geometry and dynamics of moist convection, shallow and deep, through the use of 4D images of the atmosphere water vapor field, obtained from high-density GPS networks (i.e. tomographic inversion). For this, the SWART (SEGAL GNSS WAter Vapor ReconsTruction Image Software), a software package for GNSS water vapor reconstruction, has been developed. This package currently consists of four C++ programs. The C++ programs gather the necessary information to calculate the slant delays and to generate a file with the reconstructed image. The output consists in 2D slices of the 3D water vapor image in latitude, longitude or altitude. SWART is based on LOFTT_K (LOgiciel Français de Tomographie Troposphérique version Kalman) (Champollion 2005). We present the results of the comparison with LOFTT_K to validate SWART together with several tests covering diverse grid sizes and different number of receivers for the same water vapor image reconstruction. It is also analyzed the importance of the initial values for the image reconstruction. All these tests were realized with synthetic data, except for the grid area, which is from Marseilles, France. Finally, we present the current status of the analysis being carrying out for a dense network in Belem, Brazil which data was acquired in the framework of the project CHUVA during September, 2011. This work is being carried out in the framework of the SMOG (PTDC/CTE-ATM/119922/2010) project funded by FCT. References: Champollion C., 2005: Quantification de la vapeur d'eau troposphérique par GPS (modèle 2D et tomographie 3D) - Application aux précipitations intenses. Thèse de doctorat, Laboratoire de Dynamique de la Lithosphère (Université Montpellier II).

Sá, A. G.; Bento, F.; Crocker, P.; Fernandes, R. M.; Adams, D. K.; Miranda, P. M.

2013-12-01

180

Near-field water vapor contamination observed on STS-39  

NASA Astrophysics Data System (ADS)

The analysis of CIRRIS 1A (Cryogenic InfraRed Radiance Instrumentation for Shuttle) interferometric and radiometric data obtained during the flight of STS-39 (28 Apr - 6 May 1991) reveals the presence of IR emission in the 400-900/cm (11-25 micron) region not attributable to atmospheric emission. In this paper, data are shown which identify the signal as nearfield water vapor present during all CIRRIS IA observations. Variability of the near-field water vapor emissions is characterized and compared to mass spectrometer data also obtained on STS-39 (QINMS). Further investigation indicates that the water is excited to extremely high effective temperatures, possibly in excess of 9000 K. The data presented support the theory that water outgassed from the shuttle tiles is highly excited by collisions with atmospheric O, classifying it as a type of shuttle-induced glow never before measured in the LWIR.

Dean, D.; Huppi, E. R.; Lowell, J.; Smith, D.; Sharma, R.; Wheeler, N.; Nadile, R.; Healey, R.

1992-12-01

181

Space shuttle observations of collisionally excited outgassed water vapor  

NASA Astrophysics Data System (ADS)

The analysis of CIRRIS 1A (Cryogenic InfraRed Radiance Instrumentation for Shuttle) interferometric and radiometric data obtained during the flight of STS-39 (28 Apr - 6 May 1991) reveals the presence of IR emission in the 400-900/cm (11-25 microns) region not attributable to atmospheric emission. In this paper, data are shown which identify the signal as near-field water vapor present during all CIRRIS 1A observations. Variability of the near-field water vapor emissions is characterized, and further investigation indicates that the water is excited to high effective temperatures, possibly in excess of 2000 K. The data presented support the conclusion that water outgassed from the shuttle tiles is highly excited by collisions with atmospheric O, classifying it as a type of shuttle-induced glow whose spectrum has never previously been measured in the LWIR. Measured results are compared to current models which predict radiance for collisionally excited outgassed molecules.

Dean, D. A.; Huppi, E. R.; Smith, D. R.; Nadile, R. M.; Zhou, D. K.

1994-04-01

182

Alexandrite laser transmitter development for airborne water vapor DIAL measurements  

NASA Technical Reports Server (NTRS)

In the DIAL technique, the water vapor concentration profile is determined by analyzing the lidar backscatter signals for laser wavelengths tuned 'on' and 'off' a water vapor absorption line. Desired characteristics of the on-line transmitted laser beam include: pulse energy greater than or equal to 100 mJ, high-resolution tuning capability (uncertainty less than 0.25 pm), good spectral stability (jitter less than 0.5 pm about the mean), and high spectral purity (greater than 99 percent). The off-line laser is generally detuned less than 100 pm away from the water vapor line. Its spectral requirements are much less stringent. In our past research, we developed and demonstrated the airborne DIAL technique for water vapor measurements in the 720-nm spectral region using a system based on an alexandrite laser as the transmitter for the on-line wavelength and a Nd:YAG laser-pumped dye laser for the off-line wavelength. This off-line laser has been replaced by a second alexandrite laser. Diode lasers are used to injection seed both lasers for frequency and linewidth control. This eliminates the need for the two intracavity etalons utilized in our previous alexandrite laser and thereby greatly reduces the risk of optical damage. Consequently, the transmitted pulse energy can be substantially increased, resulting in greater measurement range, higher data density, and increased measurement precision. In this paper, we describe the diode injection seed source, the two alexandrite lasers, and the device used to line lock the on-line seed source to the water vapor absorption feature.

Chyba, Thomas H.; Ponsardin, Patrick; Higdon, Noah S.; DeYoung, Russell J.; Browell, Edward V.

1995-01-01

183

Columnar water vapor retrievals from multifilter rotating shadowband radiometer data  

SciTech Connect

The Multi-Filter Rotating Shadowband Radiometer (MFRSR) measures direct and diffuse irradiances in the visible and near IR spectral range. In addition to characteristics of atmospheric aerosols, MFRSR data also allow retrieval of precipitable water vapor (PWV) column amounts, which are determined from the direct normal irradiances in the 940 nm spectral channel. The HITRAN 2004 spectral database was used in our retrievals to model the water vapor absorption. We present a detailed error analysis describing the influence of uncertainties in instrument calibration and spectral response, as well as those in available spectral databases, on the retrieval results. The results of our PWV retrievals from the Southern Great Plains (SGP) site operated by the DOE Atmospheric Radiation Measurement (ARM) Program were compared with correlative standard measurements by Microwave Radiometers (MWRs) and a Global Positioning System (GPS) water vapor sensor, as well as with retrievals from other solar radiometers (AERONET’s CIMEL, AATS-6). Some of these data are routinely available at the SGP’s Central Facility, however, we also used measurements from a wider array of instrumentation deployed at this site during the Water Vapor Intensive Observation Period (WVIOP2000) in September – October 2000. The WVIOP data show better agreement between different solar radiometers or between different microwave radiometers (both groups showing relative biases within 4%) than between these two groups of instruments, with MWRs values being consistently higher (up to 14%) than those from solar instruments. We also demonstrate the feasibility of using MFRSR network data for creation of 2D datasets comparable with the MODIS satellite water vapor product.

Alexandrov, Mikhail; Schmid, Beat; Turner, David D.; Cairns, Brian; Oinas, Valdar; Lacis, Andrew A.; Gutman, S.; Westwater, Ed R.; Smirnov, A.; Eilers, J.

2009-01-26

184

Water vapor sorption in naphthalenic sulfonated polyimide membranes  

Microsoft Academic Search

The water vapor uptake of sulfonated polyimides (SP) was investigated by electronic microbalance (IGA, Hiden) from 15 to 55°C. The sigmo??dal isotherms obtained (BET II type) are considered as dual sorption (concave part) plus clustering (convex part) and are fitted with good agreement by Park’s equation. Zimm–Lundberg’s method is used to study the clustering process of water molecules: limit clustering

Virginie Detallante; Dominique Langevin; Corinne Chappey; Michel Métayer; Régis Mercier; Michel Pinéri

2001-01-01

185

Fixation of nitrogen in the presence of water vapor  

DOEpatents

A process for the fixation of nitrogen is disclosed which comprises combining a mixture of nitrogen, oxygen, metal oxide and water vapor, initially heating the combination to initiate a reaction which forms nitrate, but at a temperature and pressure range below the dissociation pressure of the nitrate. With or without the water component, the yield of fixed nitrogen is increased by the use of a Linde Molecular Sieve Catalyst.

Harteck, Paul (Santa Barbara, CA)

1984-01-01

186

Creating water vapor barrier coatings from hydrophilic components.  

PubMed

The preparation of water vapor barrier coatings composed of polyelectrolyte/clay multilayers using the layer-by-layer technique is reported. The suitability of different synthetic and renewable polyelectrolytes for the preparation of barrier coatings in combination with montmorillonite (MMT) platelets as well as the influence of the ionic strength and the number of bilayers on the coating performance was investigated. Highly hydrophilic and permeable cellulose films were used as substrate for determining the influence of the coatings on the water vapor transmission rate (WVTR). Improved barrier properties were realized by the use of polyethylene imine (PEI) or 2-hydroxy-3-trimethylammonium propyl chloride starch (HPMA starch) in combination with MMT. After the application of only 5 bilayers of PEI and MMT (thickness ?40 nm) on each side of the cellulose film, the WVTR was significantly reduced. By the deposition of 40 PEI/MMT bilayers, the WVTR transmission rate was reduced by 68%. However, HPMA starch containing coatings led to vapor transmission reduction of up to 32% at the same number of coating steps. A strong correlation between the barrier properties of the coatings and the layer thickness was observed. The barrier properties of the coatings could be increased using higher ionic strengths. These results represent unprecedented water vapor barrier properties for coatings prepared from hydrophilic materials. PMID:22646312

Findenig, Gerald; Leimgruber, Simon; Kargl, Rupert; Spirk, Stefan; Stana-Kleinschek, Karin; Ribitsch, Volker

2012-06-27

187

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

SciTech Connect

The importance of accurate measurements of column amounts of water vapor and cloud liquid has been well documented by scientists within the Atmospheric Radiation Measurement (ARM) Program. At the North Slope of Alaska (NSA), both microwave radiometers (MWR) and the MWRProfiler (MWRP), been used operationally by ARM for passive retrievals of the quantities: Precipitable Water Vapor (PWV) and Liquid Water Path (LWP). However, it has been convincingly shown that these instruments are inadequate to measure low amounts of PWV and LWP. In the case of water vapor, this is especially important during the Arctic winter, when PWV is frequently less than 2 mm. For low amounts of LWP (< 50 g/m{sup 2}), the MWR and MWRP retrievals have an accuracy that is also not acceptable. To address some of these needs, in March-April 2004, NOAA and ARM conducted the NSA Arctic Winter Radiometric Experiment - Water Vapor Intensive Operational Period at the ARM NSA/Adjacent Arctic Ocean (NSA/AAO) site. After this experiment, the radiometer group at NOAA moved to the Center for Environmental Technology (CET) of the Department of Electrical and Computer Engineering of the University of Colorado at Boulder. During this 2004 experiment, a total of 220 radiosondes were launched, and radiometric data from 22.235 to 380 GHz were obtained. Primary instruments included the ARM MWR and MWRP, a Global Positioning System (GPS), as well as the CET Ground-based Scanning Radiometer (GSR). We have analyzed data from these instruments to answer several questions of importance to ARM, including: (a) techniques for improved water vapor measurements; (b) improved calibration techniques during cloudy conditions; (c) the spectral response of radiometers to a variety of conditions: clear, liquid, ice, and mixed phase clouds; and (d) forward modeling of microwave and millimeter wave brightness temperatures from 22 to 380 GHz. Many of these results have been published in the open literature. During the third year of this contract, we participated in another ARM-sponsored experiment at the NSA during February-March 2007. This experiment is called the Radiative Heating in Underexplored Bands Campaign (RHUBC) and the GSR was operated successfully for the duration of the campaign. One of the principal goals of the experiment was to provide retrievals of water vapor during PWV amounts less than 2 mm and to compare GSR data with ARM radiometers and radiosondes. A secondary goal was to compare the radiometric response of the microwave and millimeter wavelength radiometers to water and ice clouds. In this final report, we will include the separate progress reports for each of the three years of the project and follow with a section on major accomplishments of the project.

Westwater, Edgeworth

2011-05-06

188

Preliminary endurance tests of water vaporizers for resistojet applications  

NASA Technical Reports Server (NTRS)

Three water vaporizers designed for resistojet applications were built and tested for periods up to 500 h and 250 thermal cycles. Two of the vaporizers were not sensitive to orientation with respect to gravity, an indication of likely compatibility with low-gravity environments. Some temperatures and pressures in the third were impacted by orientation, although operation was always stable. The pressure drop across the sand-filled version increased by 147 percent in 38 h and 19 thermal cycles. Bonding of the sand granules in the downstream end of the heat exchanger was the suspected cause of failure of this vaporizer. Pressure drops across the two sintered stainless steel-filled versions were more gradual. One, with a pore size of 60 microns, showed an 80 percent increase in 500 h and 250 thermal cycles and another, with a 10 microns poresize, showed a 29 percent increase in 350 h and 175 thermal cycles. Testing of the latter metal-filled vaporizer was ongoing as of this writing. Oxidation of the porous metal packing materials in these vaporizers, with subsequent deposition of oxide particles within the pores, was believed to have caused the observed increases in pressure drops.

Morren, W. Earl; Macrae, Gregory S.

1993-01-01

189

A far-infrared radiative closure study in the Arctic: Application to water vapor  

NASA Astrophysics Data System (ADS)

Far-infrared (? > 15.0 ?m) (far-IR) radiative processes provide a large fraction of Earth's outgoing longwave radiation and influence upper tropospheric vertical motion. Water vapor, because of its abundance and strong absorption properties over an extended spectral range, is the primary source of these radiative processes. Historically, the lack of spectrally resolved radiometric instruments and the opacity of the lower atmosphere have precluded extensive studies of far-IR water vapor absorption properties. The U.S. Department of Energy Atmospheric Radiation Measurement (ARM) program has organized a series of field experiments, the Radiative Heating in Underexplored Bands Campaigns (RHUBC), to address this deficiency. The first phase of RHUBC took place in 2007 at the ARM North Slope of Alaska Climate Research Facility. Measurements taken before and during this campaign have provided the basis for a clear-sky radiative closure study aimed at reducing key uncertainties associated with far-IR radiative transfer models. Extended-range Atmospheric Emitted Radiance Interferometer infrared radiance observations taken in clear sky conditions were compared against calculations from the Line-By-Line Radiative Transfer Model. The water vapor column amounts used in these calculations were retrieved from 183 GHz radiometer measurements. The uncertainty in these integrated water vapor retrievals is approximately 2%, a notable improvement over past studies. This far-IR radiative closure study resulted in an improvement to the Mlawer-Tobin Clough-Kneiyzs-Davies (MT_CKD) water vapor foreign continuum model and updates to numerous, far-IR water vapor line parameters from their values in the circa 2006 version of the HITRAN molecular line parameter database.

Delamere, J. S.; Clough, S. A.; Payne, V. H.; Mlawer, E. J.; Turner, D. D.; Gamache, R. R.

2010-09-01

190

Alumina Volatility in Water Vapor at Elevated Temperatures  

NASA Technical Reports Server (NTRS)

The volatility of alumina in high temperature water vapor was determined by a weight loss technique. Sapphire coupons were exposed at temperatures between 1250 and 1500 C, water partial pressures between 0.15 and 0.68 atm in oxygen, total pressure of 1 atm, and flowing gas velocities of 4.4 cm/s. The pressure dependence of sapphire volatility was consistent with AI(OH)3(g) formation. The enthalpy of reaction to form Al(OH)3(g) from sapphire and water vapor was determined to be 210 +/- 20 kJ/mol, comparing favorably to other studies. Microstructural examination of tested sapphire coupons revealed surface etching features consistent with a volatilization process.

Opila, Elizabeth J.; Myers, Dwight L.

2003-01-01

191

Evaluating Global Aerosol Models and Aerosol and Water Vapor Properties Near Clouds  

SciTech Connect

The 'Evaluating Global Aerosol Models and Aerosol and Water Vapor Properties Near Clouds' project focused extensively on the analysis and utilization of water vapor and aerosol profiles derived from the ARM Raman lidar at the Southern Great Plains ARM site. A wide range of different tasks were performed during this project, all of which improved quality of the data products derived from the lidar or advanced the understanding of atmospheric processes over the site. These activities included: upgrading the Raman lidar to improve its sensitivity; participating in field experiments to validate the lidar aerosol and water vapor retrievals; using the lidar aerosol profiles to evaluate the accuracy of the vertical distribution of aerosols in global aerosol model simulations; examining the correlation between relative humidity and aerosol extinction, and how these change, due to horizontal distance away from cumulus clouds; inferring boundary layer turbulence structure in convective boundary layers from the high-time-resolution lidar water vapor measurements; retrieving cumulus entrainment rates in boundary layer cumulus clouds; and participating in a field experiment that provided data to help validate both the entrainment rate retrievals and the turbulent profiles derived from lidar observations.

Turner, David, D.; Ferrare, Richard, A.

2011-07-06

192

Stable isotopic composition of near surface atmospheric water vapor and rain-vapor interaction in Taipei, Taiwan  

NASA Astrophysics Data System (ADS)

Taiwan is an island located in the western Pacific, and falls under the influence of tropical to sub-tropical climate with two monsoons during summer and winter. This makes it an ideal location to study water vapor dynamics and its influence on the rainfall. The tropical convection/cyclones and south-west monsoon dominate the rainfall in summer while in winter, north-east monsoon overwhelms. To investigate the influence of moisture source variation, recycling and rain-vapor interaction, continuous measurements of the concentration and oxygen and hydrogen isotopic compositions (?18O and ?D) of the near surface atmospheric water vapor have been carried out in Taipei, Taiwan, using a commercial cavity ring down spectrometer. The water vapor mixing ratio varies between 15,000 and 38,000 ppmv, with maximum in the summer months and minimum in the winter. The isotopic composition of water vapor varies between -11‰ to -21‰ for ?18O and -75‰ to -150‰ for ?D, but no clear seasonal variation is observed unlike that in the monthly rainwater. Therefore, the usual assumption that the monthly composite samples of rainfall reflect the isotopic variability of near surface water vapor is not valid here. Variation in ?18O, ?D and deuterium excess (d-excess) in vapor reflects its interaction with rainwater superimposed by temperature variation and moisture recycling. To study how rainwater interacts with water vapor, two events are selected: a mei-yu event and typhoon Saola, the later affected Taiwan in 2012. Annual rainfall is dominantly contributed by these two types of meteorological phenomena in Taiwan. We find that the vapor and the rainwater are nearly in isotopic equilibrium during typhoon while they are deviated significantly during the mei-yu. A significant contribution of the vapor from recycling of surface water is observed in winter assessed using d-excess in the vapor isotopes.

Laskar, Amzad H.; Huang-Chuan, Jr.; Hsu, Shih-Chieh; Bhattacharya, Sourendra K.; Wang, Chung-Ho; Liang, Mao-Chang

2014-11-01

193

Use of a novel new irrigation system to observe and model water vapor flow through dry soils  

NASA Astrophysics Data System (ADS)

In dry soils hydraulic connectivity within the liquid water phase decreases and vapor flow becomes a significant transport mechanism for water. The temperature or solute concentration of the liquid phase affects the vapor pressure of the surrounding air, thus temperature or solute gradients can drive vapor flows. However, in extremely dry soils where water is retained by adsorption rather than capillarity, vapor flows can also occur. In such soils tiny changes in water content significantly affect the equilibrium vapor pressure in the soil, and hence small differences in water content can initiate vapor pressure gradients. In many field conditions this effect may be negligible compared to vapor flows driven by other factors. However, flows of this type are particularly significant in a new type of subsurface irrigation system which uses pervaporation, via a polymer tubing, as the mechanism for water supply. In this system, water enters the soil in vapor phase. Experiments using this system therefore provide a rare opportunity to observe vapor flows initiating from a subsurface source without significant injection of heat. A model was developed to simulate water flow through the soil in liquid and vapor phase. In this model it was assumed that the two phases were in equilibrium. The equilibrium relationship was defined by a new mathematical expression that was developed to fit experimental data collected to characterize the sorption isotherm of three soils (sand, saline sand and top soil). The osmotic potential of the saline sand was defined as a function of water content using a continuous mathematical expression. The model was then calibrated to fit the data from laboratory experiments, in which the vapor flow into and out of the soil were quantified. The model successfully reproduced experimental observations of the total water flux, relative humidity and water content distribution in three soil types. This suggests that the model, including the proposed mathematical relationship for the moisture sorption isotherm for a soil, can be used to estimate the condensation and vapor flow within soil when it is exposed to a humid vapor flux.

Todman, L. C.; Ireson, A. M.; Butler, A. P.; Templeton, M.

2013-12-01

194

John Arthur McLees, Jr. Vapor-Liquid Equilibrium of Monoethanolamine/Piperazine/Water at  

E-print Network

Copyright by John Arthur McLees, Jr. 2006 #12;Vapor-Liquid Equilibrium of Monoethanolamine/Piperazine/Water in Engineering The University of Texas at Austin May, 2006 #12;Vapor-Liquid Equilibrium of Monoethanolamine/Piperazine/Water

Rochelle, Gary T.

195

Stable Calibration of Raman Lidar Water-Vapor Measurements  

NASA Technical Reports Server (NTRS)

A method has been devised to ensure stable, long-term calibration of Raman lidar measurements that are used to determine the altitude-dependent mixing ratio of water vapor in the upper troposphere and lower stratosphere. Because the lidar measurements yield a quantity proportional to the mixing ratio, rather than the mixing ratio itself, calibration is necessary to obtain the factor of proportionality. The present method involves the use of calibration data from two sources: (1) absolute calibration data from in situ radiosonde measurements made during occasional campaigns and (2) partial calibration data obtained by use, on a regular schedule, of a lamp that emits in a known spectrum determined in laboratory calibration measurements. In this method, data from the first radiosonde campaign are used to calculate a campaign-averaged absolute lidar calibration factor (t(sub 1)) and the corresponding campaign-averaged ration (L(sub 1)) between lamp irradiances at the water-vapor and nitrogen wavelengths. Depending on the scenario considered, this ratio can be assumed to be either constant over a long time (L=L(sub 1)) or drifting slowly with time. The absolutely calibrated water-vapor mixing ratio (q) obtained from the ith routine off-campaign lidar measurement is given by q(sub 1)=P(sub 1)/t(sub 1)=LP(sub 1)/P(sup prime)(sub 1) where P(sub 1) is water-vapor/nitrogen measurement signal ration, t(sub 1) is the unknown and unneeded overall efficiency ratio of the lidar receiver during the ith routine off-campaign measurement run, and P(sup prime)(sub 1) is the water-vapor/nitrogen signal ratio obtained during the lamp run associated with the ith routine off-campaign measurement run. If L is assumed constant, then the lidar calibration is routinely obtained without the need for new radiosonde data. In this case, one uses L=L(sub 1) = P(sup prime)(sub 1)/t(sub 1), where P(sub 1)(sup prime) is the water-vapor/nitrogen signal ratio obtained during the lamp run associated with the first radiosonde campaign. If L is assumed to drift slowly, then it is necessary to postpone calculation of a(sub 1) until after a second radiosonde campaign. In this case, one obtains a new value, L(sub 2), from the second radiosonde campaign, and for the ith routine off-campaign measurement run, one uses an intermediate value of L obtained by simple linear time interpolation between L(sub 1) and L(sub 2).

Leblanc, Thierry; McDermid, Iain S.

2008-01-01

196

Raman lidar measurements of water vapor and aerosol/clouds during the FIRE/SPECTRE field campaign  

NASA Technical Reports Server (NTRS)

Water vapor is one of the most important constituents of the earth's atmosphere. It has a major impact on both atmospheric dynamics and radiative transfer. From a dynamic standpoint, the distribution of water vapor with height determines convective stability which is the major indicator of destructive storm development. Also, water vapor stored in the planetary boundary layer acts as the fuel to intensify severe weather. In regards to radiative transfer, water vapor is the most active IR molecule in the atmosphere. It is more effective in absorbing and emitting IR radiation than either carbon dioxide or methane, and thus plays an important role in global change. The main objective of FIRE (First ISSCCP (International Satellite Cloud Climatology Project) Regional Experiment) was to study the development and radiative characteristics of cirrus clouds. The SPECTRE (Spectral Radiation Experiment) project was designed to acquire the necessary atmospheric observations to compare radiative measurements with radiative transfer theory, with special emphasis on understanding the water vapor spectral continuum. The FIRE/SPECTRE field campaign was conducted during Nov. - Dec. 1991 in Coffeyville, Kansas. A complete understanding of water vapor, its distribution with height, and its temporal variation was important for both experiments.

Melfi, S. H.; Whiteman, D.; Ferrare, R.; Evans, K.; Goldsmith, J. E. M.; Lapp, M.; Bisson, S. E.

1992-01-01

197

Water vapor permeability of the rigid-shelled gecko egg.  

PubMed

The vast majority of squamate reptiles (lizards and snakes) produce parchment-shelled eggs that absorb water during incubation, and thus increase in mass, volume, and surface area. In contrast, females from a single monophyletic lineage of gekkotan lizards produce rigid-shelled eggs. These eggs are functionally comparable to those of birds, that is, at oviposition, eggs contain all the water needed for development, and their mass decreases during incubation via the diffusion of water vapor through the shell. I determined patterns of water loss and shell permeability to water vapor from oviposition to hatching for the rigid-shelled eggs of the gekkonid Chrondrodactylus turneri and compared permeability of C. turneri eggs to those of birds and other squamates. Chrondrodactylus turneri eggs incubated at 28.5°C and 40% relative humidity (RH) decreased in mass by 14% over the course of a 68-day incubation period. The rate of water loss varied during incubation; egg mass decreased rapidly during the first 8 days of incubation, declined at a low constant rate during the next 35 days, and then decreased rapidly during the final 25 days of incubation. Overall permeability was 0.17 mg/day/kPa/cm(2) . Percent water loss of rigid-shelled gecko eggs during incubation is similar to that exhibited by birds, but water vapor permeability is about one-third that of bird eggs and several orders of magnitude lower than that of parchment-shelled squamate eggs. In general, the water economy of their eggs may be associated with the adaptive radiation of the rigid-shelled sphaerodactylid, phyllodactylid, and gekkonid geckos. PMID:22777731

Andrews, Robin M

2012-07-01

198

Water Vapor Isotopic Fractionation and Strat/trop Exchange  

NASA Astrophysics Data System (ADS)

We will present atmospheric observations of the isotopic fractionation for water vapor as observed by the Smithsonian Astrophysical Observatory far-infrared spectrometer (FIRS-2). The stratospheric observations are corrected with a photochemical model to account for methane oxidation to determine the "entry level" isotopic fractionation of water in the stratosphere. These values are then compared to a simple Rayleigh frac- tionation model that includes estimations of convection, radiative heating, and mixing to infer relative contributions to stratosphere/troposphere exchange. The observations of water vapor fractionation are most consistent with a model that mixes air uplifted from roughly 11 km with significantly more air that has been dehydrated by convec- tion to an effective temperature that is much cooler than the tropopause temperature. The water vapor mixing ratio in the stratosphere results from a combination of radia- tive heating, recirculation of stratospheric air, and deep convection that supplies the air to the upper tropical troposphere. We believe that these types of observations could be a powerful tool for constraining circulation models.

Jucks, K. W.; Johnson, D. G.; Traub, W. A.; Chance, K. V.

199

ESA DUE GlobVapour water vapor products: Validation  

SciTech Connect

The main objective of the European Space Agency (ESA) Data User Element (DUE) GlobVapour project was the development of multi-annual global water vapor data sets. Since water vapour is a key climate variable it is important to have a good understanding of its behavior in the climate system. The ESA DUE GlobVapour project provides water vapor data, including error estimates, based on carefully calibrated and inter-calibrated satellite radiances in response to user requirements for long time series satellite observations. ESA DUE GlobVapour total columnar water vapor (TCWV) products derived from GOME/SCIA/GOME-2 (1996-2008) and SSM/I+MERIS (2003-2008) have been validated for the mentioned period, using satellite-based (AIRS, ATOVS) and ground-based measurements (radiosondes and microwave radiometer). The validation results are discussed in the following. The technical specifications on bias (1 kg/m{sup 2} for SSMI+MERIS and 2 kg/m{sup 2} for GOME/SCIA/GOME-2) are generally met. For more information, documents and data download follow the link: www.globvapour.info.

Schneider, Nadine; Schroeder, Marc; Stengel, Martin [Deutscher Wetterdienst (DWD), KU22, Frankfurter Str. 135, 63067 Offenbach a. M (Germany); Lindstrot, Ramus; Preusker, Rene [Freie Universitaet Berlin (FUB), Carl-Heinrich-Becker-Weg 6-10, 12165 Berlin (Germany); Collaboration: ESA DUE GlobVapour Consortium

2013-05-10

200

Monitoring the water vapor isotopic composition in the North Atlantic  

NASA Astrophysics Data System (ADS)

Water stable isotopes have during many decades been used as climate proxies and indicators for variations in the hydrological cycle. However we are to a great extent still using simple empirical relationships without any deeper theoretical understanding. In order to properly relate changes in the climate and hydrological cycle to changes in the observed stable water isotopic signal we must understand the underlying physical processes. Furthermore it is a challenge for General Climate Models to adequately represent the isotopes in the hydrological cycle because of lack of in-situ measurements of the atmospheric water-vapor composition in the source regions. During the fall of 2010 we installed an autonomous water vapor spectroscopy laser (from Los Gatos Research) in a lighthouse on the South Coast of Iceland (63.83 N 21.47W) with the plan to be operational for several years. The purpose of this installation was through monitoring of the water vapor isotopic composition to understand the physical processes governing the isotopic composition of the water vapor evaporated from the ocean as well as the processes of mixing between the free troposphere and marine boundary layer. Because of the remoteness of the monitoring site and simple topography we are able to isolate the 'fingerprint' on the isotopic signal in the water vapor from respectively the ocean and the interior highland leading to a near perfect case-study area. Using back-trajectories we find a strong influence of the origin of the air masses on the measured isotopic composition. The mixing of the marine-boundary layer is found to strongly influence the measured isotopic composition. The second order isotopic parameter, d-excess, is found to depend on both the isotopic composition as well as the relative humidity as prescribed by theories for evaporation from an ocean. The site likely represents a major source region for the moisture that later falls as snow on parts of the Greenland Ice Sheet. This leads to a better understanding of the processes, which create the climatic signal in the water isotopic signal found in ice cores drilled on the ice sheet.

Sveinbjornsdottir, A. E.; Steen-Larsen, H.; Jonsson, T.; Johnsen, S. J.

2011-12-01

201

Wavelength-modulation laser hygrometer for ultrasensitive detection of water vapor in  

E-print Network

Water vapor has been measured at nanomole-per-mole levels by use of lead-salt la- sers,9Wavelength-modulation laser hygrometer for ultrasensitive detection of water vapor in semiconductor gases David Christian Hovde, Joseph T. Hodges, Gregory E. Scace, and Joel A. Silver Water vapor

202

Water vapor continuum: absorption measurements at 350GHz and model calculations  

NASA Astrophysics Data System (ADS)

Absolute absorption rates of pure water vapor and mixtures of water vapor and nitrogen have been measured in the laboratory at 350 GHz. The dependence on pressure and temperature has been obtained. Additionally, a water vapor continuum parameter estimation, taking even the previous laboratory measurements from 150 to 350 GHz into account, is performed.

Kuhn, T.; Bauer, A.; Godon, M.; Buhler, S.; Kunzi, K.

2002-09-01

203

Remote Sensing of Atmospheric Water Vapor with the Global Positioning System  

E-print Network

Remote Sensing of Atmospheric Water Vapor with the Global Positioning System A Dissertation John: Remote Sensing of Atmospheric Water Vapor with the Global Positioning System Written by John Joseph Braun Water Vapor with the Global Positioning System Thesis directed by Professor Judith Curry Signals from

204

Observation of water vapor in the stratosphere of Jupiter with the Odin Space Telescope  

E-print Network

Observation of water vapor in the stratosphere of Jupiter with the Odin Space Telescope T. Cavali, USA Abstract The water vapor line at 557 GHz has been observed with the Odin space telescope, spectroscopy, Odin space telescope 1 Introduction1 The Infrared Space Observatory has detected water vapor

Paris-Sud XI, Université de

205

The Role of Water Vapor Feedback in Unperturbed Climate Variability and Global Warming  

Microsoft Academic Search

To understand the role of water vapor feedback in unperturbed surface temperature variability, a version of the Geophysical Fluid Dynamics Laboratory coupled ocean-atmosphere model is integrated for 1000 yr in two configurations, one with water vapor feedback and one without. For all spatial scales, the model with water vapor feedback has more low-frequency (timescale 2 yr) surface temperature variability than

Alex Hall; Syukuro Manabe

1999-01-01

206

Remote sensing of water vapor in the near IR from EOS\\/MODIS  

Microsoft Academic Search

The LOWTRAN-7 code was used to simulate remote sensing of water vapor over 20 different surface covers. The simulation was used to optimize the water vapor channel selection and to test the accuracy of the remote sensing method. The channel selection minimizes the uncertainty in the derived water vapor due to variations in the spectral dependence of the surface reflectance.

Yoram J. Kaufman; Bo-Cai Gao

1992-01-01

207

Agricultural and Forest Meteorology 105 (2000) 161183 Spatial and temporal properties of water vapor and  

E-print Network

. The LE flux was derived from lidar-measured water vapor and simultaneous point-sensor wind A scanning, volume-imaging Raman lidar was used in August 1997 to map the water vapor and latent energy flux mesquite-grass community. The lidar derived water vapor images showed microscale convective structures

Williams, David G.

208

3080 VOLUME 13J O U R N A L O F C L I M A T E Water Vapor Feedbacks in the ECMWF Reanalyses and Hadley Centre Climate Model  

E-print Network

Experiment (ERBE) and retrievals of column water vapor (CWV) from microwave radiometers. Raval and Ramanathan the geographical distributions of the clear-sky greenhouse effect, water vapor, and SST to infer3080 VOLUME 13J O U R N A L O F C L I M A T E Water Vapor Feedbacks in the ECMWF Reanalyses

Allan, Richard P.

209

Water vapor, water-ice clouds, and dust in the North Polar Region  

NASA Technical Reports Server (NTRS)

The behavior of water vapor, water-ice and dust in the Martian atmosphere is important for understanding the overall Martian climate system, which is characterized by three main cycles: water, including water-ice, dust, and CO2. Understanding these cycles will lend insight into the behavior of the atmospheric dynamics, the atmosphere's ability to transport dust, water-ice, and vapor to different parts of the planet, and how that ability changes as a function of dust and water-ice loading.

Tamppari, Leslie K.; Smith, Michael D.; Bass, Deborah S.; Hale, Amy S.

2006-01-01

210

Evapotranspiration partitioning in a semi-arid African savanna using stable isotopes of water vapor  

NASA Astrophysics Data System (ADS)

Evapotranspiration (ET) represents a major flux of water out of semi-arid ecosystems. Thus, understanding ET dynamics is central to the study of African savanna health and productivity. At our study site in central Kenya (Mpala Research Centre), we have been using stable isotopes of water vapor to partition ET into its constituent parts of plant transpiration (T) and soil evaporation (E). This effort includes continuous measurement (1 Hz) of ?2H and ?18O in water vapor using a portable water vapor isotope analyzer mounted on a 22.5 m eddy covariance flux tower. The flux tower has been collecting data since early 2010. The isotopic end-member of ?ET is calculated using a Keeling Plot approach, whereas ?T and ?E are measured directly via a leaf chamber and tubing buried in the soil, respectively. Here we report on a two recent sets of measurements for partitioning ET in the Kenya Long-term Exclosure Experiment (KLEE) and a nearby grassland. We combine leaf level measurements of photosynthesis and water use with canopy-scale isotope measurements for ET partitioning. In the KLEE experiment we compare ET partitioning in a 4 ha plot that has only seen cattle grazing for the past 15 years with an adjacent plot that has undergone grazing by both cattle and wild herbivores (antelope, elephants, giraffe). These results are compared with a detailed study of ET in an artificially watered grassland.

Soderberg, K.; Good, S. P.; O'Connor, M.; King, E. G.; Caylor, K. K.

2012-04-01

211

Water vapor analysis with use of sunphotometry and radiosoundings  

NASA Astrophysics Data System (ADS)

Information about vertically integrated content of water vapor in the atmosphere and type, composition and concentration of aerosols is relevant in many types of atmospheric studies. Such information is required to understand mechanisms of global climate and its further modeling (Smirnov et al., 2000). This work is devoted to the description of a basic technique of analysis and comparing the derivation of Columnar Water Vapor (CWV) from different instruments, such as a radiosonde and a sunphotometer. The measurements were carried out using Microtops II Ozone Monitor & Sunphotometer during the cruises onboard the R/V Oceania (13 cruises) and from one cruise onboard of the SY TASK in the southern Baltic Sea. Measurements were collected for the NASA program Maritime Aerosol Network. Data collected with the DiGICORA III Radiosonde (RS92) come from the webpage of the University of Wyoming, Department of Atmospheric Science. The first instrument, sunphotometer, allows us to collect data on days that are cloud-free. The Microtops II is capable of measuring the total ozone column, total precipitable water vapor and aerosol optical depth at 1020 nm (Morys et al. 2001; Ichoku et al., 2002). Each of these parameters is automatically derived. Data collected by Microtops have been processed with the pre- and post-field calibration and automatic cloud clearing. Precipitable water vapor in the column was derived from the 936nm channel. Detailed data description is available on the AERONET webpage. In radiousoundings the total precipitable water is the water that occurs in a vertical column of a unit cross-sectional area between any two specified levels, commonly expressed as from the earth's surface to the 'top' of the atmosphere. The Integrated Precipitable Water Vapor (IPWV) is the height of liquid water that would result from the condensation of all water vapor in a column. The study of one cruise (29 March - 20 April) shows that 241 Microtops measurements were made, each of them in a series of five 'shots'. Then only the lowest value was chose. Then the data were matched with the radiosonde data, based on date and time. The example result with the selected data for the comparison shows that the correlation is strong for both instruments (0.67), despite of low data number that left to compare. The correlation between aerosol optical depth and water vapor content in the total atmospheric column is not high (0.42). Also diurnal variations of the aerosol optical depth and precipitable water were insignificant (AOD=0.09±0.03;PWV =11.42±3.50). Some of the differences in correlation can be attributed to the distance between location of the instruments and to the reference instrument, as well as the conditions in the atmosphere like wind speed and its direction. These analyses are presented in order to quantify the accuracy of different techniques and algorithms to estimate WV present in the Earth's atmosphere. Nevertheless, the data comparison shows discrepancy at a lower level between the instruments. The support for this study was provided by the POLAND-AOD network and the project Satellite Monitoring of the Baltic Sea Environment - SatBa?tyk founded by European Union through European Regional Development Fund contract No. POIG 01.01.02-22-011/09.

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

2014-05-01

212

Isobaric vapor-liquid equilibrium for ethanol + water + sodium nitrate  

SciTech Connect

The salt effect on the vapor-liquid equilibrium of mixed solvents provides a potential technique of extractive distillation, in which a dissolved salt, rather than a liquid additive, is used as the separating agent. This salt distillation process has been used in the purification of close-boiling, azeotropic, and other systems which are difficult to separate. The isobaric vapor-liquid equilibrium for ethanol (1) + water (2) + sodium nitrate (3) at various concentrations of salt and with ethanol mole fractions from 0 to 0.774 has been measured at 100.0 kPa. The results were correlated by assuming that the salt was in ionic form and it was associated only with the water.

Pena, M.P.; Vercher, E.; Martinez-Andreu, A. [Univ. de Valencia (Spain). Dept. de Ingenieria Quimica] [Univ. de Valencia (Spain). Dept. de Ingenieria Quimica

1996-09-01

213

Self-deactivation of water vapor - Role of the dimer  

NASA Technical Reports Server (NTRS)

A phenomenological multiple-relaxation theory of the deactivation rate constant for the nu-2 (1 - 0) bending mode of water vapor is presented which incorporates the role not only of the excited monomer but also of the bound molecular complex, in particular the dimer. The deactivation takes place by means of three parallel processes: (1) collisional deexcitation of the excited monomer, (2) a two-step reaction involving association and spontaneous redissociation of an H2O collision complex, and (3) spontaneous dissociation of the stably bound H2O dimer. Oxygen, but not nitrogen or argon, serves as an effective chaperon for the formation of the activated complex. This observation explains the impurity dependence of the self-deactivation rate constant of water vapor. Analysis of an ultrasonic absorption peak based on the third process yields values for the standard entropy and enthalpy of dissociation of the stably bound H2O dimer.

Zuckerwar, A. J.

1984-01-01

214

Water vapor continuum: Whether collision-induced absorption is involved?  

NASA Astrophysics Data System (ADS)

In a series of recent publications, the idea is pursued to shed a new light on the theory of the water vapor continuum absorption invoking the mechanism of collision-induced absorption. In the opinion of the present author, a portion of theoretical suggestions on this subject is biased and may thus lead to untenable conclusions about the nature of the continuum. The most typical drawback consists of improper consideration of statistics in the ensemble of interacting monomers that lead to embedding incorrect statistical weights to various types of molecular pairs which can form. The current note aims at clarifying the term “collision-induced absorption” in order to avoid incongruity in understanding the nature of the water vapor continuum.

Vigasin, A. A.

2014-11-01

215

Space shuttle observations of collisionally excited outgassed water vapor  

Microsoft Academic Search

The analysis of CIRRIS 1A (Cryogenic InfraRed Radiance Instrumentation for Shuttle) interferometric and radiometric data obtained during the flight of STS-39 (28 Apr - 6 May 1991) reveals the presence of IR emission in the 400-900\\/cm (11-25 microns) region not attributable to atmospheric emission. In this paper, data are shown which identify the signal as near-field water vapor present during

D. A. Dean; E. R. Huppi; D. R. Smith; R. M. Nadile; D. K. Zhou

1994-01-01

216

Space shuttle observations of collisionally excited outgassed water vapor  

Microsoft Academic Search

The analysis of CIRRIS 1A (Cryogenic InfraRed Radiance Instrumentation for Shuttle) interferometric and radiometric data obtained during the flight of STS-39 (28 Apr–6 May 1991) reveals the presence of IR emission in the 400–900 cm?1 (11–25 ?m) region not attributable to atmospheric emission. In this paper, data are shown which identify the signal as near-field water vapor present during all

D. A. Dean; E. R. Huppi; D. R. Smith; R. M. Nadile; D. K. Zhou

1994-01-01

217

Near-field water vapor contamination observed on STS39  

Microsoft Academic Search

The analysis of CIRRIS 1A (Cryogenic InfraRed Radiance Instrumentation for Shuttle) interferometric and radiometric data obtained during the flight of STS-39 (28 Apr - 6 May 1991) reveals the presence of IR emission in the 400-900\\/cm (11-25 micron) region not attributable to atmospheric emission. In this paper, data are shown which identify the signal as nearfield water vapor present during

D. Dean; E. R. Huppi; J. Lowell; D. Smith; R. Sharma; N. Wheeler; R. Nadile; R. Healey

1992-01-01

218

Feasibility study of ammonia-water vapor absorption heat transformer  

Microsoft Academic Search

Many industrial sectors reject heat to the atmosphere in the form of hot water with a temperature between 40° and 70°C. This low grade heat can be upgraded by using a vapor absorption heat transformer (AHT). The present study considers a single stage AHT with binary mixture of NHâ-HâO as the working fluid. The performance characteristics of the system have

A. Ertas; P. Gandhidasan; J. J. Luthan

1987-01-01

219

Extratropical influence of upper tropospheric water vapor on Greenhouse warming  

NASA Technical Reports Server (NTRS)

Despite its small quantity, the importance of upper tropospheric water vapor is its ability to trap the longwave radiation emitted from the Earth's surface, namely the greenhouse effect. The greenhouse effect is defined quantitatively as the difference between the longwave flux emitted by the Earth's surface and the outgoing longwave radiation (OLR) flux emitted from the top of the atmosphere (TOA) (Raval and Ramanathan 1989).

Liu, W. Timothy; Hu, Hua

1997-01-01

220

Radiative Sensitivity to Water Vapor under All-Sky Conditions  

Microsoft Academic Search

Using the National Center for Atmospheric Research Community Climate Model, version 3, radiation transfer model and a realistic tropospheric environment including the International Satellite Cloud Climatology Project cloud fields, all-sky radiative sensitivity to water vapor is assessed. The analysis improves upon previous clear-sky and model-based studies by using observed clouds, assessing realistic vertically varying perturbations, and considering spatial gradients in

John Fasullo; De-Zheng Sun

2001-01-01

221

Water vapor variance measurements using a Raman lidar  

NASA Technical Reports Server (NTRS)

Because of the importance of atmospheric water vapor variance, we have analyzed data from the NASA/Goddard Raman lidar to obtain temporal scales of water vapor mixing ratio as a function of altitude over observation periods extending to 12 hours. The ground-based lidar measures water vapor mixing ration from near the earth's surface to an altitude of 9-10 km. Moisture profiles are acquired once every minute with 75 m vertical resolution. Data at each 75 meter altitude level can be displayed as a function of time from the beginning to the end of an observation period. These time sequences have been spectrally analyzed using a fast Fourier transform technique. An example of such a temporal spectrum obtained between 00:22 and 10:29 UT on December 6, 1991 is shown in the figure. The curve shown on the figure represents the spectral average of data from 11 height levels centered on an altitude of 1 km (1 plus or minus .375 km). The spectra shows a decrease in energy density with frequency which generally follows a -5/3 power law over the spectral interval 3x10 (exp -5) to 4x10 (exp -3) Hz. The flattening of the spectrum for frequencies greater than 6x10 (exp -3) Hz is most likely a measure of instrumental noise. Spectra like that shown in the figure are calculated for other altitudes and show changes in spectral features with height. Spectral analysis versus height have been performed for several observation periods which demonstrate changes in water vapor mixing ratio spectral character from one observation period to the next. The combination of these temporal spectra with independent measurements of winds aloft provide an opportunity to infer spatial scales of moisture variance.

Evans, K.; Melfi, S. H.; Ferrare, R.; Whiteman, D.

1992-01-01

222

Column atmospheric water vapor and vegetation liquid water retrievals from airborne imaging spectrometer data  

SciTech Connect

High spatial resolution column atmospheric water vapor amounts were derived from spectral data collected by the airborne visible-infrared imaging spectrometer (AVIRIS). The quantitative derivation is made by curve fitting observed spectra with calculated spectra in the 1.14-{mu}m and 0.94-{mu}m water vapor band absorption regions using an atmospheric model, a narrow-band spectral model, and a nonlinear least squares fitting technique. The derivation makes use of the facts that (1) the reflectances of many ground targets vary approximately linearly with wavelength in the 0.94- and 1.14-{mu}m water vapor band absorption regions, (2) the scattered radiation near 1 {mu}m is small compared with the directly reflected radiation when the atmospheric aerosol concentrations are low, and (3) the scattered radiation in the lower part of the atmosphere is subjected to the water vapor absorption. Based on the analyses of an AVIRIS data set that was acquired within an hour of radiosonde launch, it appears that the accuracy approaches the precision. The derived column water vapor amounts are independent of the absolute surface reflectances. It now appears feasible to derive high spatial resolution column water vapor amounts over land areas from satellite altitude with the proposed high resolution imaging spectrometer (HIRIS). Curve fitting of spectra near 1 {mu}m from areas covered with vegetation, using an atmospheric model and a simplified vegetation reflectance model, indicates that both the amount of atmospheric water vapor and the moisture content of vegetation can be retrieved simultaneously because the band centers of liquid water in vegetation and the atmospheric water vapor are offset by approximately 0.05 {mu}m.

Bo-Cai Gao; Goetz, A.F.H. (Univ. of Colorado, Boulder (United States))

1990-03-20

223

Adsorption characteristics of water vapor on honeycomb adsorbents  

NASA Astrophysics Data System (ADS)

Recovery of tritium released into working areas in nuclear fusion plants is a key issue of safety. A large volume of air from tritium fuel cycle or vacuum vessel should be processed by air cleanup system (ACS). In ACS, tritium gas is oxidized by catalysts, and then tritiated water vapor is collected by adsorbents. This method can remove tritium effectively, whereas high throughput of air causes high-pressure drop in catalyst and adsorbent beds. In this study, the applicability of honeycomb-type adsorbents, which offers a useful advantage in terms of their low-pressure drop, to ACS was examined, in comparison with conventional pebble-type adsorbent. Honeycomb-type adsorbent causes far less pressure drop than pebble-type adsorbent beds. Adsorption capacity of water vapor on a honeycomb-type adsorbent is slightly lower than that on a pebble-type adsorbent, while adsorption rate of water vapor on honeycomb-type adsorbent is much higher than that of pebble-type adsorbent.

Wajima, Takaaki; Munakata, Kenzo; Takeishi, Toshiharu; Hara, Keisuke; Wada, Kouhei; Katekari, Kenichi; Inoue, Keita; Shinozaki, Yohei; Mochizuki, Kazuhiro; Tanaka, Masahiro; Uda, Tatsuhiko

2011-10-01

224

Relation between 183 GHz Water Vapor Line and Water Continuum Absorption Measured with FTS  

NASA Astrophysics Data System (ADS)

ve carried out Fourier Transform Spectrometer (FTS) measurements of the millimeter and submillimeter-wave (100-1500 GHz or 3 mm - 200 micron) atmospheric opacity at Pampa la Bola, 4800 m above sea level in northern Chile on September 1997 and June 1998. Correlations between 220 GHz opacities and those of the center of submillimeter-wave windows were obtained using the entire data set, and good correlations were obtained except for the periods affected by the liquid water opacity component. We succeeded to separate the total opacity to water vapor and liquid water opacity components. The separated water vapor opacity component shows good correlation with the 183 GHz pure water vapor line opacity, which is also covered in the measured spectra, but the liquid water opacity component shows no correlation. Since the submillimeter-wave opacity is merely affected by the liquid water component, it may be better to use the submillimeter-wave opacity for the phase correction.

Matsushita, S.; Matsuo, H.

225

Liquid-vapor oscillations of water in hydrophobic nanopores  

PubMed Central

Water plays a key role in biological membrane transport. In ion channels and water-conducting pores (aquaporins), one-dimensional confinement in conjunction with strong surface effects changes the physical behavior of water. In molecular dynamics simulations of water in short (0.8 nm) hydrophobic pores the water density in the pore fluctuates on a nanosecond time scale. In long simulations (460 ns in total) at pore radii ranging from 0.35 to 1.0 nm we quantify the kinetics of oscillations between a liquid-filled and a vapor-filled pore. This behavior can be explained as capillary evaporation alternating with capillary condensation, driven by pressure fluctuations in the water outside the pore. The free-energy difference between the two states depends linearly on the radius. The free-energy landscape shows how a metastable liquid state gradually develops with increasing radius. For radii > ?0.55 nm it becomes the globally stable state and the vapor state vanishes. One-dimensional confinement affects the dynamic behavior of the water molecules and increases the self diffusion by a factor of 2–3 compared with bulk water. Permeabilities for the narrow pores are of the same order of magnitude as for biological water pores. Water flow is not continuous but occurs in bursts. Our results suggest that simulations aimed at collective phenomena such as hydrophobic effects may require simulation times >50 ns. For water in confined geometries, it is not possible to extrapolate from bulk or short time behavior to longer time scales. PMID:12740433

Beckstein, Oliver; Sansom, Mark S. P.

2003-01-01

226

In search of water vapor on Jupiter: Laboratory measurements of the microwave properties of water vapor under simulated jovian conditions  

NASA Astrophysics Data System (ADS)

Detection and measurement of atmospheric water vapor in the deep jovian atmosphere using microwave radiometry has been discussed extensively by Janssen et al. (Janssen, M.A., Hofstadter, M.D., Gulkis, S., Ingersoll, A.P., Allison, M., Bolton, S.J., Levin, S.M., Kamp, L.W. [2005]. Icarus 173 (2), 447-453.) and de Pater et al. (de Pater, I., Deboer, D., Marley, M., Freedman, R., Young, R. [2005]. Icarus 173 (2), 425-447). The NASA Juno mission will include a six-channel microwave radiometer system (MWR) operating in the 1.3-50 cm wavelength range in order to retrieve water vapor abundances from the microwave signature of Jupiter (see, e.g., Matousek, S. [2005]. The Juno new frontiers mission. Tech. Rep. IAC-05-A3.2.A.04, California Institute of Technology). In order to accurately interpret data from such observations, nearly 2000 laboratory measurements of the microwave opacity of H2O vapor in a H2/He atmosphere have been conducted in the 5-21 cm wavelength range (1.4-6 GHz) at pressures from 30 mbars to 101 bars and at temperatures from 330 to 525 K. The mole fraction of H2O (at maximum pressure) ranged from 0.19% to 3.6% with some additional measurements of pure H2O. These results have enabled development of the first model for the opacity of gaseous H2O in a H2/He atmosphere under jovian conditions developed from actual laboratory data. The new model is based on a terrestrial model of Rosenkranz et al. (Rosenkranz, P.W. [1998]. Radio Science 33, 919-928), with substantial modifications to reflect the effects of jovian conditions. The new model for water vapor opacity dramatically outperforms previous models and will provide reliable results for temperatures from 300 to 525 K, at pressures up to 100 bars and at frequencies up to 6 GHz. These results will significantly reduce the uncertainties in the retrieval of jovian atmospheric water vapor abundances from the microwave radiometric measurements from the upcoming NASA Juno mission, as well as provide a clearer understanding of the role deep atmospheric water vapor may play in the decimeter-wavelength spectrum of Saturn.

Karpowicz, Bryan M.; Steffes, Paul G.

2011-03-01

227

Water Vapor and Cirrus Clouds in the Pacific TTL during ATTREX 2013 (Invited)  

NASA Astrophysics Data System (ADS)

Despite its very low mixing ratios relative to the troposphere, water vapor in the lower stratosphere (LS) plays a significant role in Earth's radiative balance and climate system and is an important constituent in stratospheric chemistry. The low H2O content of air entering the LS is established to first order by dehydration processes controlled by the cold temperatures of the tropical tropopause layer (TTL). However, uncertainties in aspects of the nucleation and growth of cirrus cloud particles and the sparseness of in situ water vapor and cirrus cloud observations with sufficient spatial resolution limit our ability to fully describe the final stages of the dehydration process before air enters the LS in the tropics. The NASA Airborne Tropical Tropopause Experiment (ATTREX) measurement campaign is using the long endurance NASA Global Hawk UAS to acquire observations of water vapor and cirrus cloud properties in order to improve understanding of TTL dehydration processes. ATTREX completed 6 flights in February-March 2013, including numerous vertical profiles through the TTL in the central and eastern Pacific during a period with a high, cold tropopause. Cirrus clouds were encountered near the tropopause (17-18 km) with varied ice crystal number and ice water content and water vapor mixing ratios as low as 1.5 ppm. The mean value for relative humidity with respect to ice inside cirrus clouds was close to 100%, but encompassed a range from < 50% to higher than 150%. We present an analysis of the ATTREX 2013 measurements to characterize the structure of the Pacific TTL with respect to water vapor, cirrus clouds and dehydration. The ATTREX data provide a basis by which our current assumptions about the dehydration of air passing through the TTL can be evaluated.

Thornberry, T. D.; Rollins, D. W.; Gao, R.; Fahey, D. W.; Bui, T. V.; Lawson, P.; McGill, M. J.

2013-12-01

228

Potential energy of atmospheric water vapor and the air motions induced by water vapor condensation on different spatial scales  

E-print Network

Basic physical principles are considered that are responsible for the origin of dynamic air flow upon condensation of water vapor, the partial pressure of which represents a store of potential energy in the atmosphere of Earth. Quantitative characteristics of such flow are presented for several spatial scales. It is shown that maximum condensation-induced velocities reach 160 m/s and are realized in compact circulation patterns like tornadoes.

Anastassia M. Makarieva; Victor G. Gorshkov

2010-03-29

229

Water vapor heterogeneity related to tropopause folds over the North Atlantic revealed by airborne water vapor differential absorption lidar  

Microsoft Academic Search

Airborne differential absorption lidar (DIAL) measurements of tropospheric water vapor and aerosol\\/clouds are presented from transfers across the North Atlantic on 13–15 May and 16–18 June 2002. The intense dynamical activity over the Atlantic is reflected in complex structures like deep tropopause folds, extended dry layers, and tilted aerosol filaments. Intrusions with H2O mixing ratios below 0.03 g kg?1 regularly

H. Flentje; A. Dörnbrack; G. Ehret; A. Fix; C. Kiemle; G. Poberaj; M. Wirth

2005-01-01

230

Deuterium excess reveals diurnal sources of water vapor in forest air.  

PubMed

An understanding of atmospheric water vapor content and its isotopic composition is important if we are to be able to model future water vapor dynamics and their potential feedback on future climate change. Here we present diurnal and vertical patterns of water isotope ratios in forest air (?(2)H(v) and ?(18)O(v)) not observed previously. Water vapor observed at three heights over 3 consecutive days in a coniferous forest in the Pacific Northwest of the United States, shows a stratified nocturnal structure of ?(2)H(v) and ?(18)O(v), with the most positive values consistently observed above the canopy (60 m). Differences between 0.5 m and 60 m range between 2-6‰ for ?(18)O and 20-40‰ for ?(2)H at night. Using a box model, we simulated H(2)O isotope fluxes and showed that the low to high ?(2)H(v) and ?(18)O(v) profiles can be explained by the vapor flux associated with evaporation from the forest floor and canopy transpiration. We used d-excess as a diagnostic tracer to identify processes that contribute to the diurnal variation in atmospheric moisture. Values of d-excess derived from water vapor measurements showed a repeated diel pattern, with the lowest values occurring in the early morning and the highest values occurring at midday. The isotopic composition of rain water, collected during a light rain event in the first morning of our experiment, suggested that considerable below-cloud secondary evaporation occurred during the descent of raindrops. We conclude that atmospheric entrainment appears to drive the isotopic variation of water vapor in the early morning when the convective boundary layer rapidly develops, while evapotranspiration becomes more important in the mid-afternoon as a primary moisture source of water vapor in this forest. Our results demonstrate the interplay between the effects of vegetation and boundary layer mixing under the influence of rain evaporation, which has implications for larger-scale predictions of precipitation across the terrestrial landscape. PMID:20652594

Lai, Chun-Ta; Ehleringer, James R

2011-01-01

231

enhanced) in water vapor. The distribution of water ice throughout the solar nebula may  

E-print Network

enhanced) in water vapor. The distribution of water ice throughout the solar nebula may have varied of solids that are a few hundred times greater than that of the canonical solar nebula (14). Turbulent, radial drift of ice particles from the snow line may have enhanced water ice in the solar nebula from 3

Utrecht, Universiteit

232

Cloud and Aerosol Properties, Precipitable Water, and Profiles of Temperature and Water Vapor from MODIS  

E-print Network

Cloud and Aerosol Properties, Precipitable Water, and Profiles of Temperature and Water Vapor from, NASA Goddard Space Flight Center, Greenbelt, MD 20771 USA (e- mail: king@climate.gsfc.nasa.gov). W. P such as cloud mask, atmos- pheric profiles, aerosol properties, total precipitable water, and cloud properties

Sheridan, Jennifer

233

Water vapor variability and comparisons in the subtropical Pacific from The Observing System Research and Predictability Experiment-Pacific Asian Regional Campaign (T-PARC) Driftsonde, Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC), and reanalyses  

NASA Astrophysics Data System (ADS)

During the THORPEX (The Observing System Research and Predictability Experiment) Pacific Asian Regional Campaign (T-PARC), from 1 August to 30 September 2008, ˜1900 high-quality, high vertical resolution soundings were collected over the Pacific Ocean. These include dropsondes deployed from four aircrafts and zero-pressure balloons in the stratosphere (NCAR's Driftsonde system). The water vapor probability distribution and spatial variability in the northern subtropical Pacific (14°-20°N, 140°E-155°W) are studied using Driftsonde and COSMIC (Constellation Observing System for Meteorology, Ionosphere, and Climate) data and four global reanalysis products. Driftsonde data analysis shows distinct differences of relative humidity (RH) distributions in the free troposphere between the Eastern and Western Pacific (EP and WP, defined as east and west of 180°, respectively), very dry with a single peak of ˜1% RH in the EP and bi-modal distributions in the WP with one peak near ice saturation and one varying with altitude. The frequent occurrences of extreme dry air are found in the driftsonde data with 59% and 19% of RHs less than or equal to 5% and at 1% at 500 hPa in the EP, respectively. RH with respect to ice in the free troposphere exhibits considerable longitudinal variations, very low (<20%) in the EP, but varying from 20% to 100% in the WP. Inter-comparisons of Driftsonde, COSMIC and reanalysis data show generally good agreement among the Driftsonde, COSMIC, ECMWF Reanalysis-Interim (ERA-Interim) and Japanese Reanalysis (JRA) below 200 hPa. The ERA-Interim and JRA are approved to be successful on describing RH frequency distributions and spatial variations in the region. The comparisons also reveal problems in Driftsonde, two National Center for Environmental Prediction (NCEP) reanalyses and COSMIC data. The moist layer at 200-100 hPa in the WP shown in the ERA-Interim, JRA and COSMIC is missing in Driftsonde data. Major problems are found in the RH means and variability over the study region for both NCEP reanalyses. Although the higher-moisture layer at 200-100 hPa in the WP in the COSMIC data agrees well with the ERA-Interim and JRA, it is primarily attributed to the first guess of the 1-Dimensional (1D) variational analysis used in the COSMIC retrieval rather than the refractivity measurements. The limited soundings (total 268) of Driftsonde data are capable of portraying RH probability distributions and longitudinal variability. This implies that Driftsonde system has the potential to become a valuable operational system for upper air observations over the ocean.

Wang, Junhong; Zhang, Liangying; Lin, Po-Hsiung; Bradford, Mark; Cole, Harold; Fox, Jack; Hock, Terry; Lauritsen, Dean; Loehrer, Scot; Martin, Charlie; Vanandel, Joseph; Weng, Chun-Hsiung; Young, Kathryn

2010-11-01

234

Water vapor from a lunar breccia - Implications for evolving planetary atmospheres.  

NASA Technical Reports Server (NTRS)

The exposure of a typical complex lunar breccia to hydrogen after a through outgassing produces a fully reduced surface state. Subsequent outgassing over a wide temperature range results in the production of water vapor formed from the chemisorbed hydrogen and oxygen from the lunar sample; the proposed mechanism has been confirmed in terms of the chemisorption of deuterium and the release of heavy water. Since the conditions of the experiments are consistent with those on the lunar surface, it is postulated that water vapor will be produced on the moon through the interaction of the solar wind with lunar soil. It is also proposed that such a process could play an important role in the early history of many planets where an oxygen-rich soil is exposed to a reducing atmosphere.

Cadenhead, D. A.; Buergel, W. G.

1973-01-01

235

Microwave Remote Sensing: Clouds, Precipitation, and Water Vapor  

NSDL National Science Digital Library

This module provides an introduction to polar-orbiting-satellite-based microwave remote sensing products that depict moisture and precipitation in the atmosphere. The module begins with definitions and descriptions of total precipitable water and cloud liquid water products, contrasting each with more familiar infrared water vapor and window channel products. This is followed by an overview of microwave precipitation estimation and a discussion of how polar-satellite products compare with those from geostationary satellites and ground-based radar. A series of case examples highlights potential weather forecasting applications for total precipitable water and precipitation products. The module also includes an introduction to the Global Precipitation Monitoring Mission to which future NPOESS satellites will be an important contributor. This module takes about 75 minutes to complete.

Comet

2006-10-06

236

Observed Seasonal to Decadal-Scale Responses in Mesospheric Water Vapor  

NASA Technical Reports Server (NTRS)

The 14-yr (1991-2005) time series of mesospheric water vapor from the Halogen Occultation Experiment (HALOE) are analyzed using multiple linear regression (MLR) techniques for their6 seasonal and longer-period terms from 45S to 45N. The distribution of annual average water vapor shows a decrease from a maximum of 6.5 ppmv at 0.2 hPa to about 3.2 ppmv at 0.01 hPa, in accord with the effects of the photolysis of water vapor due to the Lyman-flux. The distribution of the semi-annual cycle amplitudes is nearly hemispherically symmetric at the low latitudes, while that of the annual cycles show larger amplitudes in the northern hemisphere. The diagnosed 11-yr, or solar cycle, max minus min, water vapor values are of the order of several percent at 0.2 hPa to about 23% at 0.01 hPa. The solar cycle terms have larger values in the northern than in the southern hemisphere, particularly in the middle mesosphere, and the associated linear trend terms are anomalously large in the same region. Those anomalies are due, at least in part, to the fact that the amplitudes of the seasonal cycles were varying at northern mid latitudes during 1991-2005, while the corresponding seasonal terms of the MLR model do not allow for that possibility. Although the 11-yr variation in water vapor is essentially hemispherically-symmetric and anti-phased with the solar cycle flux near 0.01 hPa, the concurrent temperature variations produce slightly colder conditions at the northern high latitudes at solar minimum. It is concluded that this temperature difference is most likely the reason for the greater occurrence of polar mesospheric clouds at the northern versus the southern high latitudes at solar minimum during the HALOE time period.

Remsberg, Ellis

2010-01-01

237

Fiber-Optic Gratings for Lidar Measurements of Water Vapor  

NASA Technical Reports Server (NTRS)

Narrow-band filters in the form of phase-shifted Fabry-Perot Bragg gratings incorporated into optical fibers are being developed for differential-absorption lidar (DIAL) instruments used to measure concentrations of atmospheric water vapor. The basic idea is to measure the relative amounts of pulsed laser light scattered from the atmosphere at two nearly equal wavelengths, one of which coincides with an absorption spectral peak of water molecules and the other corresponding to no water vapor absorption. As part of the DIAL measurement process, the scattered light is made to pass through a filter on the way to a photodetector. Omitting other details of DIAL for the sake of brevity, what is required of the filter is to provide a stop band that: Surrounds the water-vapor spectral absorption peaks at a wavelength of 946 nm, Has a spectral width of at least a couple of nanometers, Contains a pass band preferably no wider than necessary to accommodate the 946.0003-nm-wavelength water vapor absorption peak [which has 8.47 pm full width at half maximum (FWHM)], and Contains another pass band at the slightly shorter wavelength of 945.9 nm, where there is scattering of light from aerosol particles but no absorption by water molecules. Whereas filters used heretofore in DIAL have had bandwidths of =300 pm, recent progress in the art of fiber-optic Bragg-grating filters has made it feasible to reduce bandwidths to less than or equal to 20 pm and thereby to reduce background noise. Another benefit of substituting fiber-optic Bragg-grating filters for those now in use would be significant reductions in the weights of DIAL instruments. Yet another advantage of fiber-optic Bragg-grating filters is that their transmission spectra can be shifted to longer wavelengths by heating or stretching: hence, it is envisioned that future DIAL instruments would contain devices for fine adjustment of transmission wavelengths through stretching or heating of fiber-optic Bragg-grating filters nominally designed and fabricated to have transmission wavelengths that, in the absence of stretching, would be slightly too short.

Vann, Leila B.; DeYoung, Russell J.

2006-01-01

238

WATER VAPOR IN THE PROTOPLANETARY DISK OF DG Tau  

SciTech Connect

Water is key in the evolution of protoplanetary disks and the formation of comets and icy/water planets. While high-excitation water lines originating in the hot inner disk have been detected in several T Tauri stars (TTSs), water vapor from the outer disk, where most water ice reservoirs are stored, was only reported in the nearby TTS TW Hya. We present spectrally resolved Herschel/HIFI observations of the young TTS DG Tau in the ortho- and para-water ground-state transitions at 557 and 1113 GHz. The lines show a narrow double-peaked profile, consistent with an origin in the outer disk, and are {approx}19-26 times brighter than in TW Hya. In contrast, CO and [C II] lines are dominated by emission from the envelope/outflow, which makes H{sub 2}O lines a unique tracer of the disk of DG Tau. Disk modeling with the thermo-chemical code ProDiMo indicates that the strong UV field, due to the young age and strong accretion of DG Tau, irradiates a disk upper layer at 10-90 AU from the star, heating it up to temperatures of 600 K and producing the observed bright water lines. The models suggest a disk mass of 0.015-0.1 M{sub Sun }, consistent with the estimated minimum mass of the solar nebula before planet formation, and a water reservoir of {approx}10{sup 2}-10{sup 3} Earth oceans in vapor and {approx}100 times larger in the form of ice. Hence, this detection supports the scenario of ocean delivery on terrestrial planets by the impact of icy bodies forming in the outer disk.

Podio, L.; Dougados, C.; Thi, W.-F.; Menard, F.; Pinte, C. [UJF-Grenoble 1/CNRS-INSU, Institut de Planetologie et d'Astrophysique de Grenoble (IPAG) UMR 5274, F-38041 Grenoble (France); Kamp, I.; Meijerink, R.; Spaans, M.; Aresu, G. [Kapteyn Astronomical Institute, University of Groningen, Landleven 12, 9747 AD Groningen (Netherlands); Codella, C. [INAF-Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, I-50125 Florence (Italy); Cabrit, S. [LERMA, UMR 8112 du CNRS, Observatoire de Paris, Ecole Normale Superieure, Universite Pierre et Marie Curie, Universite de Cergy-Pontoise, 61 Av. de l'Observatoire, F-75014 Paris (France); Nisini, B. [INAF-Osservatorio Astronomico di Roma, via di Frascati 33, I-00040 Monte Porzio Catone (Italy); Sandell, G. [SOFIA-USRA, NASA Ames Research Center, MS 232-12, Building N232, Rm. 146, P.O. Box 1, Moffett Field, CA 94035-0001 (United States); Williams, J. P. [Institute for Astronomy (IfA), University of Hawaii, 2680 Woodlawn Dr., Honolulu, HI 96822 (United States); Testi, L. [European Southern Observatory, Karl-Schwarzschild-Strasse 2, D-85748 Garching (Germany); Woitke, P. [SUPA, School of Physics and Astronomy, University of St. Andrews, KY16 9SS (United Kingdom)

2013-03-20

239

Water Vapor in the Protoplanetary Disk of DG Tau  

NASA Astrophysics Data System (ADS)

Water is key in the evolution of protoplanetary disks and the formation of comets and icy/water planets. While high-excitation water lines originating in the hot inner disk have been detected in several T Tauri stars (TTSs), water vapor from the outer disk, where most water ice reservoirs are stored, was only reported in the nearby TTS TW Hya. We present spectrally resolved Herschel/HIFI observations of the young TTS DG Tau in the ortho- and para-water ground-state transitions at 557 and 1113 GHz. The lines show a narrow double-peaked profile, consistent with an origin in the outer disk, and are ~19-26 times brighter than in TW Hya. In contrast, CO and [C II] lines are dominated by emission from the envelope/outflow, which makes H2O lines a unique tracer of the disk of DG Tau. Disk modeling with the thermo-chemical code ProDiMo indicates that the strong UV field, due to the young age and strong accretion of DG Tau, irradiates a disk upper layer at 10-90 AU from the star, heating it up to temperatures of 600 K and producing the observed bright water lines. The models suggest a disk mass of 0.015-0.1 M ?, consistent with the estimated minimum mass of the solar nebula before planet formation, and a water reservoir of ~102-103 Earth oceans in vapor and ~100 times larger in the form of ice. Hence, this detection supports the scenario of ocean delivery on terrestrial planets by the impact of icy bodies forming in the outer disk.

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

2013-03-01

240

Reduction of Convection in Closed Tube Vapor Transport Experiments  

NASA Technical Reports Server (NTRS)

The primary objective of this effort was to develop a method for suppressing convective flows during the growth of mercurous chloride crystals by vapor transport in closed tubes to levels approaching those obtained in the microgravity environment. Mercurous chloride was chosen because it is a technologically interesting acoustical optical material whose optical properties are believed to be affected by convective flows. Since the Grashof number scales as the cube of the smallest dimension in the flow system, reduction of the size scale can be extremely effective in reducing unwanted convective flows. However, since materials of practical interest must be grown at least on the cm scale, reduction of the overall growth system is not feasible. But if the region just above the growing crystal could be restricted to a few mm, considerable reduction in flow velocity would result. By suspending an effusive barrier in the growth ampoule just above the growth interface, it should be possible to reduce the convective velocity in this vicinity to levels approaching flows in microgravity. If successful, this growth technique will offer a screening test for proposed space experiments that involve vapor transport to see if reduction of convection will result in improved material and will set a new standard against which the improvements obtained in microgravity may be judged. In addition, it may provide an improved method for preparing materials on Earth whose growth is affected adversely by convection. If the properties of this material can be improved there is a potential commercial interest from Brimrose Inc., who has agreed to fabricate and test devices from the crystals we have grown. This report describes the development of the growth facility, the purification processes developed for preparing the starting material, and the results from growth experiments with and without the effusive baffle. Mercurous chloride turned out to be a more difficult material to deal with than originally anticipated. At growth temperatures, it is extremely sensitive to practically any impurity which causes it to form oxychlorides and/or to decompose into elemental mercury and bichloride of mercury. We were unable to find a suitable method for protecting the magnetic material used to suspend the effusion barrier from the attack of mercurous chloride vapor. Although we were successful in growing single crystals of mercurous chloride without the effusion baffle, they exhibited severe microcracking which we attribute to wall-induced thermal stresses. This leads us to believe that uncontrolled convection may not be the most important problem in the development of this material and a new growth process was attempted that eliminates the wall-induced stress. Unfortunately, the grant ran out before this new method could be adequately tested.

Naumann, R. J.; Tan, Sarwa Bakti; Shin, In-Seok; Kim, Joo Soo

2002-01-01

241

Atmospheric water vapor monitoring above the Greenland Ice Sheet  

NASA Astrophysics Data System (ADS)

From ice cores drilled on the Greenland and Antarctic Ice sheet we are able to measure a suite of climate proxies. Of these climate proxies, one of the routinely measured is the water stable isotope ratio in terms of the ratio H218O/H216O and HD16O/H216O (known as ?18O and ?D). Based on these relationships, the past temperatures of the site and source region can be estimated. The relation between the isotopic composition and temperature is based on direct observations with only limited understanding of the underlying physical processes. New insights into the physical properties of the hydrological cycle have recently been possible with development of field deployable laser-spectroscopy analyzers. We present here measurements carried out during the 2010 field season, at the NEEM site in NW-Greenland (77.45 N 51.05 W, 2484 m a.s.l.). The field campaign lasted more than two months during June, July and August. The measurements were conducted in the clean air zone upwind from the NEEM camp. A 13-meter tower was erected and a system was sat up to take in air from six different levels of respectively 1.0, 1.5, 3.0, 7.0, 10.0, and 13.0 meters height above the snow surface. The isotopic composition of the vapor was measured for 15 minutes at each level before shifting to the next level. The isotopic water vapour was measured in continuous mode using a Picarro Inc. and a Los Gatos Inc. water vapor analyzer. As part of the field deployment a comparison between the two different isotopic water vapor analyzers were carried out together with a validation of both the long and short-term stability of the systems. We conclude from these tests that both analyzers present a large reproducibility and stability, which gives merits to the obtained results. We observe a clear diurnal cycle in the isotopic composition of the water vapor above the snow surface with amplitude of about 15 o/oo in ?D. The diurnal isotopic composition follows the absolute humidity cycle. This indicates a large flux of vapor from the snow surface to the atmosphere during the daily warming and reverse flux during the daily cooling. The isotopic measurements of the flux of water vapor above the snow give new insights into the post depositional processes of the isotopic composition of the snow. Over the complete field deployment we observe relative stable d-excess (d-excess = ?D - 8x?18O) level of about 20 o/oo only to be interrupted by intrusion of shorter periods lasting about 1-2 days with very high d-excess levels of up to 50 o/oo. We perform backtrajectory simulations and find that for periods with high d-excess level the air mass originates from the Arctic Ocean above the North American Continent. We explain the observed high d-excess by strong kinetic fractionation during evaporation from the sea into humidity-depleted air as it moves across the sea ice margin. These new insights are valuable in our understanding of the climate signal deduced from the stable water isotopic signal measured in the ice cores drilled on the Greenland and Antarctic Ice Sheet.

Steen-Larsen, H. C.; Johnsen, S. J.; Masson-Delmotte, V.; Stenni, B.; Risi, C.; Sodemann, H.

2012-04-01

242

A comparative study of mesospheric water vapor measurements from the ground-based water vapor millimeter-wave spectrometer and space-based instruments  

Microsoft Academic Search

We compare water vapor measurements from the Naval Research Laboratory ground- based Water Vapor Millimeter-wave Spectrometer (WVMS) instruments with measurements taken by five space-based instruments. For coincident measurements the retrievals from all of the instruments show qualitatively similar altitude profiles. The retrieved mixing ratios from most instruments generally differ from an average calculated using retrievals from all of the instruments

Gerald E. Nedoluha; Richard M. Bevilacqua; R. Michael Gomez; William B. Waltman; Brian C. Hicks; D. L. Thacker; James M. Russell; Mark Abrams; Hugh C. Pumphrey; Brian J. Connor

1997-01-01

243

Gas scavenging of insoluble vapors: Condensation of methyl salicylate vapor onto evaporating drops of water  

NASA Astrophysics Data System (ADS)

We have observed the evaporation of acoustically levitated water drops at 0 and 32% relative humidity in a moving gas stream which is nearly saturated with methyl salicylate vapor. The initial evaporation rate is characteristic of a pure water drop and gradually slows until the evaporation rate becomes that of pure methyl salicylate. The quantity of condensed methyl salicylate exceeds its Henry's law solubility in water by factors of more than 30-50. This apparent violation of Henry's law agrees with the concentration enhancements in the liquid phase found by glotfelty et al. (1987, Nature235, 602-605) during their field measurements of organophorus pesticides in fog water. Under our conditions, visual evidence demonstrates the presence of two liquid phases, thus invalidating the use of Henry's law. A continuum evaporation-condensation model for an immiscible two-component system which accounts for evaporative self-cooling of the drop correctly predicts the amount of methyl salicylate condensed onto the water drops.

Seaver, Mark; Peele, J. R.; Rubel, Glenn O.

244

FTS Measurements of Submillimeter-Wave Atmospheric Opacity at Pampa la Bola III. Water Vapor, Liquid Water, and 183 GHz Water Vapor Line Opacities  

E-print Network

Further analysis has been made on the millimeter and submillimeter-wave (100-1600 GHz or 3 mm - 188 micron) atmospheric opacity data taken with the Fourier Transform Spectrometer (FTS) at Pampa la Bola, 4800 m above sea level in northern Chile, which is the site of the Atacama Large Millimeter/submillimeter Array (ALMA). Time-sequence plots of millimeter and submillimeter-wave opacities show similar variations to each other, except for during the periods with liquid water (fog or clouds) in the atmosphere. Using millimeter and submillimeter-wave opacity correlations under two conditions, which are affected and not affected by liquid water, we succeeded to separate the measured opacity into water vapor and liquid water opacity components. The water vapor opacity shows good correlation with the 183 GHz water vapor line opacity, which is also covered in the measured spectra. On the other hand, the liquid water opacity and the 183 GHz line opacity show no correlation. Since only the water vapor component is expected to affect the phase of interferometers significantly, and the submillimeter-wave opacity is less affected by the liquid water component, it may be possible to use the submillimeter-wave opacity for a phase-correction of submillimeter interferometers.

Satoki Matsushita; Hiroshi Matsuo

2003-02-03

245

FTS Measurements of Submillimeter-Wave Atmospheric Opacity at Pampa la Bola: III. Water Vapor, Liquid Water, and 183GHz Water Vapor Line Opacities  

NASA Astrophysics Data System (ADS)

Further analysis has been made on the millimeter- and submillimeter-wave (100-1600GHz or 3mm-188 ?m) atmospheric opacity data taken with the Fourier Transform Spectrometer (FTS) at Pampa la Bola, 4800 m above the sea level in northern Chile, which is the site of the Atacama Large Millimeter/submillimeter Array (ALMA). Time-sequence plots of millimeter- and submillimeter-wave opacities show similar variations to each other, except for during the periods with liquid water (fog or clouds) in the atmosphere. Using millimeter- and submillimeter-wave opacity correlations under two conditions, which are affected and not affected by liquid water, we succeeded to separate the measured opacity into water vapor and liquid water opacity components. The water vapor opacity shows a good correlation with the 183GHz water vapor line opacity, which is also covered in the measured spectra. On the other hand, the liquid water opacity and the 183GHz line opacity show no correlation. S ince only the water vapor component is expected to affect the phase of interferometers significantly, and the submillimeter-wave opacity is less affected by the liquid water component, it may be possible to use the submillimeter-wave opacity for a phase correction of submillimeter interferometers.

Matsushita, Satoki; Matsuo, Hiroshi

2003-02-01

246

Oxidation of Ultra High Temperature Ceramics in Water Vapor  

NASA Technical Reports Server (NTRS)

Ultra High Temperature Ceramics (UHTCs) including HfB2 + 20v/0 SiC (HS), ZrB2 + 20v/0 SiC (ZS), and ZrB2 + 30v/0 C + 14v/0 SiC (ZCS) have been investigated for use as potential aeropropulsion engine materials. These materials were oxidized in water vapor (90 percent) using a cyclic vertical furnace at 1 atm. The total exposure time was 10 h at temperatures of 1200, 1300, and 1400 C. CVD SiC was also evaluated as a baseline for comparison. Weight change, X-ray diffraction analyses, surface and cross-sectional SEM and EDS were performed. These results are compared with tests ran in a stagnant air furnace at temperatures of 1327 C for 100 min, and with high pressure burner rig (HPBR) results at 1100 and 1300 C at 6 atm for 50 h. Low velocity water vapor does not make a significant contribution to the oxidation rates of UHTCs when compared to stagnant air. The parabolic rate constants at 1300 C, range from 0.29 to 16.0 mg(sup 2)cm(sup 4)/h for HS and ZCS, respectively, with ZS results between these two values. Comparison of results for UHTCs tested in the furnace in 90 percent water vapor with HPBR results was difficult due to significant sample loss caused by spallation in the increased velocity of the HPBR. Total recession measurements are also reported for the two test environments.

Nguyen, QuynhGiao N.; Opila, Elizabeth J.; Robinson, Raymond C.

2004-01-01

247

An optical water vapor sensor for unmanned aerial vehicles  

SciTech Connect

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

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

1998-12-01

248

Titanium Dioxide Volatility in High Temperature Water Vapor  

NASA Technical Reports Server (NTRS)

Titanium (Ti) containing materials are of high interest to the aerospace industry due to its high temperature capability, strength, and light weight. As with most metals an exterior oxide layer naturally exists in environments that contain oxygen (i.e. air). At high temperatures, water vapor plays a key role in the volatility of materials including oxide surfaces. This study will evaluate cold pressed titanium dioxide (TiO2) powder pellets at a temperature range of 1400 C - 1200 C in water containing environments to determine the volatile hydroxyl species using the transpiration method. The water content ranged from 0-76 mole% and the oxygen content range was 0-100 mole % during the 20-250 hour exposure times. Preliminary results indicate that oxygen is not a key contributor at these temperatures and the following reaction is the primary volatile equation for all three temperatures: TiO2 (s) + H2O (g) = TiO(OH)2 (g).

Nguyen, QynhGiao N.

2008-01-01

249

Paralinear Oxidation of CVD SiC in Water Vapor  

NASA Technical Reports Server (NTRS)

The oxidation kinetics of CVD SiC were monitored by thermogravimetric analysis (TGA) in a 50% H2O/50% O2 gas mixture flowing at 4.4 cm/s for temperatures between 1200 and 1400 C. Paralinear weight change kinetics were observed as the water vapor oxidized the SiC and simultaneously volatilized the silica scale. The long-term degradation rate of SiC is determined by the volatility of the silica scale. Rapid SiC surface recession rates were estimated from these data for actual aircraft engine combustor conditions.

Opila, Elizabeth J.; Hann, Raiford E., Jr.

1997-01-01

250

Interactions of Water Vapor with Oxides at Elevated Temperatures  

NASA Technical Reports Server (NTRS)

Many volatile metal hydroxides form by reaction of the corresponding metal oxide with water vapor. These reactions are important in a number of high temperature corrosion processes. Experimental methods for studying the thermodynamics of metal hydroxides include: gas leak Knudsen cell mass spectrometry, free jet sampling mass spectrometry, transpiration and hydrogen-oxygen flame studies. The available experimental information is reviewed and the most stable metal hydroxide species are correlated with position in the periodic table. Current studies in our laboratory on the Si-O-H system are discussed.

Jacobson, Nathan; Opila, Elizabeth; Copland, Evan; Myers, Dwight

2003-01-01

251

Airborne water vapor DIAL research: System development and field measurements  

NASA Technical Reports Server (NTRS)

This paper describes the airborne differential absorption lidar (DIAL) system developed at the NASA Langley Research Center for remote measurement of water vapor (H2O) and aerosols in the lower atmosphere. The airborne H2O DIAL system was flight tested aboard the NASA Wallops Flight Facility (WFF) Electra aircraft in three separate field deployments between 1989 and 1991. Atmospheric measurements were made under a variety of atmospheric conditions during the flight tests, and several modifications were implemented during this development period to improve system operation. A brief description of the system and major modifications will be presented, and the most significant atmospheric observations will be described.

Higdon, Noah S.; Browell, Edward V.; Ponsardin, Patrick; Chyba, Thomas H.; Grossmann, Benoist E.; Butler, Carolyn F.; Fenn, Marta A.; Mayor, Shane D.; Ismail, Syed; Grant, William B.

1992-01-01

252

Reaction of water vapor with a clean liquid uranium surface  

SciTech Connect

To study the reaction of water vapor with uranium, we have exposed clean liquid uranium surfaces to H/sub 2/O under UHV conditions. We have measured the surface concentration of oxygen as a function of exposure, and determined the maximum attainable surface oxygen concentration X/sub 0//sup s/ as a function of temperature. We have used these measurements to estimate, close to the melting point, the solubility of oxygen (X/sub 0//sup b/, < 10/sup -4/) and its surface segregation coefficient ..beta../sup s/(> 10/sup 3/). 8 refs., 5 figs., 1 tab.

Siekhaus, W.

1985-10-24

253

Using microwave observations to assess large-scale control of free tropospheric water vapor in the mid-latitudes  

E-print Network

Using microwave observations to assess large-scale control of free tropospheric water vaporGL026240. 1. Introduction [2] Radiative effects due to changes in atmospheric water vapor of midlatitude water vapor is evaluated through reconstructions of the water vapor field using a Lagrangian

Brogniez, Hélène

254

Final Report for ARM Project Measuring 4-D Water Vapor Fields with GPS  

SciTech Connect

Water vapor is a primary element in the Earth’s climate system. Atmospheric water vapor is central to cloud processes, radiation transfer, and the hydrological cycle. Using funding from Department of Energy (DOE) grant DE-FG03-02ER63327, the University Corporation for Atmospheric Research (UCAR) developed new observational techniques to measure atmospheric water vapor and applied these techniques to measure four dimensional water vapor fields throughout the United States Southern Great Plains region. This report summarizes the development of a new observation from ground based Global Positioning System (GPS) stations called Slant Water Vapor (SW) and it’s utilization in retrieving four dimensional water vapor fields. The SW observation represents the integrated amount of water vapor between a GPS station and a transmitting satellite. SW observations provide improved temporal and spatial sampling of the atmosphere when compared to column-integrated quantities such as preciptitable water vapor (PW). Under funding from the DOE Atmospheric Radiation Measurement (ARM) program, GPS networks in the Southern Great Plains (SGP) region were deployed to retrieve SW to improve the characterization of water vapor throughout the region. These observations were used to estimate four dimensional water vapor fields using tomographic approaches and through assimilation into the MM5 numerical weather model.

Braun, John

2006-02-06

255

FTS Measurements of Submillimeter-Wave Atmospheric Opacity at Pampa la Bola III. Water Vapor, Liquid Water, and 183 GHz Water Vapor Line Opacities  

E-print Network

Further analysis has been made on the millimeter and submillimeter-wave (100-1600 GHz or 3 mm - 188 micron) atmospheric opacity data taken with the Fourier Transform Spectrometer (FTS) at Pampa la Bola, 4800 m above sea level in northern Chile, which is the site of the Atacama Large Millimeter/submillimeter Array (ALMA). Time-sequence plots of millimeter and submillimeter-wave opacities show similar variations to each other, except for during the periods with liquid water (fog or clouds) in the atmosphere. Using millimeter and submillimeter-wave opacity correlations under two conditions, which are affected and not affected by liquid water, we succeeded to separate the measured opacity into water vapor and liquid water opacity components. The water vapor opacity shows good correlation with the 183 GHz water vapor line opacity, which is also covered in the measured spectra. On the other hand, the liquid water opacity and the 183 GHz line opacity show no correlation. Since only the water vapor component is expec...

Matsushita, S; Matsushita, Satoki; Matsuo, Hiroshi

2003-01-01

256

Kunming experiences water shortage  

SciTech Connect

This article examines a Chinese city's measures to plan the water supply and conserve water, and to ensure a regular supply of water to drink and use in production. The Kunming city government called an emergency mobilization meeting on water conservation. Kunming has suffered from a severe lack of rainfall over the past 2 years. In order to overcome the present water shortage, it was decided to publicize the importance of planning the water supply and water conservation; to set limits on the amount of water used and to crack down on large consumers of water; and to make further rational and scientific uses of water. The Kunming government has proposed saving 20% of the water now being consumed.

Sun Chaozhen

1983-07-17

257

The Water Vapor Abundance in Orion KL Outflows  

E-print Network

We present the detection and modeling of more than 70 far-IR pure rotational lines of water vapor, including the 18O and 17O isotopologues, towards Orion KL. Observations were performed with the Long Wavelength Spectrometer Fabry-Perot (LWS/FP; R~6800-9700) on board the Infrared Space Observatory (ISO) between ~43 and ~197 um. The water line profiles evolve from P-Cygni type profiles (even for the H2O18 lines) to pure emission at wavelengths above ~100 um. We find that most of the water emission/absorption arises from an extended flow of gas expanding at 25+-5 kms^-1. Non-local radiative transfer models show that much of the water excitation and line profile formation is driven by the dust continuum emission. The derived beam averaged water abundance is 2-3x10^-5. The inferred gas temperature Tk=80-100 K suggests that: (i) water could have been formed in the "plateau" by gas phase neutral-neutral reactions with activation barriers if the gas was previously heated (e.g. by shocks) to >500 K and/or (ii) H2O formation in the outflow is dominated by in-situ evaporation of grain water-ice mantles and/or (iii) H2O was formed in the innermost and warmer regions (e.g. the hot core) and was swept up in ~1000 yr, the dynamical timescale of the outflow.

J. Cernicharo; J. R. Goicoechea; F. Daniel; M. R. Lerate; M. J. Barlow; B. M. Swinyard; E. van Dishoeck; T. L. Lim; S. Viti; J. Yates

2006-08-16

258

CHARM: A CubeSat Water Vapor Radiometer for Earth Science  

NASA Technical Reports Server (NTRS)

The Jet Propulsion Laboratory (JPL) and Ames Research Center (ARC) are partnering in the CubeSat Hydrometric Atmospheric Radiometer Mission (CHARM), a water vapor radiometer integrated on a 3U CubeSat platform, selected for implementation under NASA Hands-On Project Experience (HOPE-3). CHARM will measure 4 channels at 183 GHz water vapor line, subsets of measurements currently performed by larger and more costly spacecraft (e.g. ATMS, AMSU-B and SSMI/S). While flying a payload that supports SMD science objectives, CHARM provides a hands-on opportunity to develop technical, leadership, and project skills. CHARM will furthermore advance the technology readiness level (TRL) of the 183 GHz receiver subsystem from TRL 4 to TRL 6 and the CubeSat 183 GHz radiometer system from TRL 4 to TRL 7.

Lim, Boon; Mauro, David; DeRosee, Rodolphe; Sorgenfrei, Matthew; Vance, Steve

2012-01-01

259

Kunming experiences water shortage  

Microsoft Academic Search

This article examines a Chinese city's measures to plan the water supply and conserve water, and to ensure a regular supply of water to drink and use in production. The Kunming city government called an emergency mobilization meeting on water conservation. Kunming has suffered from a severe lack of rainfall over the past 2 years. In order to overcome the

Sun Chaozhen

1983-01-01

260

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

NASA Astrophysics Data System (ADS)

The ?18O and ?D of atmospheric water vapor provide rich information on the hydrological cycle and gaseous exchange processes between the terrestrial vegetation and the atmosphere. In the past, the majority of water vapor isotope studies have relied on discrete sampling using cold-trap/mass spectrometry methods. Recent development of isotope ratio infrared spectroscopy (IRIS) has made it possible to make in-situ, continuous observations of the ?18O and ?D of atmospheric water vapor. In this paper, we report the results of an inter-comparison experiment using three commercial IRIS analyzers. These analyzers were developed on the basis of tunable diode laser absorption spectroscopy (model TGA100A, Campbell Scientific Inc., Logan, UT), off-axis integrated cavity output spectroscopy (model DLT-100, Los Gatos Research, Mountain View, CA) and wavelength-scanned cavity ring-down spectroscopy (models L1115-i and L1102-i, Picarro Inc., Sunnyvale, CA). Each analyzer was calibrated, at factory recommended frequencies, with its own calibration device traceable to the same working standard. The experiment consisted of two parts each lasting 2 weeks. First, the ?18O and ?D of ambient water vapor from a common intake were measured simultaneously with these analyzers. The data reported for hourly intervals were analyzed to reveal how well these analyzers track natural variability in ambient conditions. Second, a home-made bubbler combined with dry air was used for performance evaluation under controlled conditions. The bubbler produced a moisture stream that followed the Rayleigh prediction, and with appropriate mixing with dry air provided a sufficient range of humidity at preset levels of mixing ratio (30,000, 20,000, 10,000, 5,000 ppm). Analysis of the experimental data is underway to (1) evaluate the relative precision and accuracy among these analyzers, (2) compare the measured isotopic ratios against the Rayleigh prediction, and (3) identify appropriate calibration frequencies for long-term unattended operation.

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

2010-12-01

261

Ground-based lidar measurements of ozone, water vapor, and aerosols in the lower stratosphere and troposphere  

SciTech Connect

Lidar measurements of ozone and water vapor concentrations were performed during several field experiments in 1980-1981 by means of the differential absorption laser technique. Profiles up to 26 km for ozone and up to 9 km for water vapor are presented. Also, a lidar survey of aerosol layers ranging from 12 to 23 km were performed following the Mt. St. Helens major eruption (May 1980). Experiments were conducted at the CNRS lidar facility of the Haute Provence Observatory which is located in southern France (44/sup 0/N, 5/sup 0/E). For ozone a vertical profile is recorded in three sequences, each requiring 15 min of acquisition time. The relative accuracy is better than 5% at the lower altitude and falls to 20% at 25 km. For water vapor the time sequences are 4 min or 8 min long and the accuracy is better than 10% in the lower troposphere.

Flamant, P.H. (Jet Propulsion Lab., Pasadena, CA; CNRS, Laboratoire de Meteorologie Dynamique, Palaiseau, Essonne, France); Pelon, J. (CNRS, Service d'Aeronomie, Verrieres-le-Buisson, Essonne, France); Lefrere, J. (Electricite de France, Direction des Etudes et Recherches, Chatou, Yvelines, France)

1982-01-01

262

Interannual Variability in the Meridional Transport of Water Vapor  

NASA Technical Reports Server (NTRS)

The zonal-mean meridional transport of water vapor across the globe is evaluated using the National Centers for Environmental Prediction-National Center for Atmospheric Research (NCEP-NCAR) reanalysis for 1948-97. The shape of the meridional profile of the climatological mean transport closely resembles that of previous mean climate descriptions, but values tend to be notably larger than in climatologies derived from radiosonde-only-based analyses. The unprecedented length of the NCEP-NCAR dataset invites a focus on interannual variations in the zonal-mean moisture transport, and these results for northern winter are highlighted here. Although interannual variability in the transport is typically small at most latitudes, a significant ENSO signal is present, marked by a strengthening of water vapor transports over much of the winter hemisphere during warm events. Because of an increase in tropical sea surface temperatures and in the frequency of warm events relative to cold events in the latter half of the 50-yr record, this interannual signal projects onto an overall trend toward enhanced meridional moisture transports in the global hydrological cycle.

Cohen, Judah L.; Salstein, David A.; Rosen, Richard D.

2000-01-01

263

Micropulse water vapor differential absorption lidar: transmitter design and performance.  

PubMed

An all diode-laser-based micropulse differential absorption lidar (DIAL) laser transmitter for tropospheric water vapor and aerosol profiling is presented. The micropulse DIAL (MPD) transmitter utilizes two continuous wave (cw) external cavity diode lasers (ECDL) to seed an actively pulsed, overdriven tapered semiconductor optical amplifier (TSOA). The MPD laser produces up to 7 watts of peak power over a 1 µs pulse duration (7 µJ) and a 10 kHz pulse repetition frequency. Spectral switching between the online and offline seed lasers is achieved on a 1Hz basis using a fiber optic switch to allow for more accurate sampling of the atmospheric volume between the online and offline laser shots. The high laser spectral purity of greater than 0.9996 coupled with the broad tunability of the laser transmitter will allow for accurate measurements of tropospheric water vapor in a wide range of geographic locations under varying atmospheric conditions. This paper describes the design and performance characteristics of a third generation MPD laser transmitter with enhanced laser performance over the previous generation DIAL system. PMID:23187280

Nehrir, Amin R; Repasky, Kevin S; Carlsten, John L

2012-10-22

264

The evolution of water vapor in the atmosphere of Venus.  

NASA Technical Reports Server (NTRS)

Examination of the feasibility of loss of water vapor from the Venus atmosphere, assuming H2O as the sole initial constituent. A steady-state model is constructed, and the photochemistry establishes the distribution of important products in the upper atmosphere. Calculations of exospheric temperatures yield values as high as 100,000 K. Such large temperatures result from the large abundance of atomic hydrogen in the exosphere, and imply a dynamic outflow of all constituents from the upper region of the atmosphere. Such an outflow would cause the escape of all hydrogen and some of the oxygen resulting from dissociation of H2O. Little loss of CO2 would result, due to its low abundance in the upper region, permitting its accumulation to the present observed value. It is concluded that if Venus formed from the same mix of materials as the earth, much tectonic activity and fairly rapid outgassing must have occurred during the early phase of its history to account for the loss of water vapor.

Smith, L. L.; Gross, S. H.

1972-01-01

265

Water vapor in the protoplanetary disk of DG Tau  

E-print Network

Water is key in the evolution of protoplanetary disks and the formation of comets and icy/water planets. While high excitation water lines originating in the hot inner disk have been detected in several T Tauri stars (TTSs), water vapor from the outer disk, where most of water ice reservoir is stored, was only reported in the closeby TTS TW Hya. We present spectrally resolved Herschel/HIFI observations of the young TTS DG Tau in the ortho- and para- water ground-state transitions at 557, 1113 GHz. The lines show a narrow double-peaked profile, consistent with an origin in the outer disk, and are ~19-26 times brighter than in TW Hya. In contrast, CO and [C II] lines are dominated by emission from the envelope/outflow, which makes H2O lines a unique tracer of the disk of DG Tau. Disk modeling with the thermo-chemical code ProDiMo indicates that the strong UV field, due to the young age and strong accretion of DG Tau, irradiates a disk upper layer at 10-90 AU from the star, heating it up to temperatures of 600 K...

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

2013-01-01

266

Back-trajectory Analyses of Water Vapor in Northern Mongolia  

NASA Astrophysics Data System (ADS)

Knowledge of precipitation sources is indispensable for prediction of extreme events as droughts and flood [Dirmeyer and Brubaker, 1999]. In this paper, the transport pathways of water vapor that precipitates in northern Mongolia were identified using back-trajectory analyses in order to find out factors causing such events in arid/semi-arid area. First, a back-trajectory model of atmospheric water vapor was developed. An air parcel is placed on an isentropic plane over the target site at each time of precipitation. Then, back trajectories was calculated with a kinematic method following the implicit technique [Merrill et al., 1986; Merrill, 1989]. Each of the air parcels was tagged with the precipitation time and the altitude, and then tracked back in time for 5 days on the isentropic surface. Japanese 25-year Reanalysis/JMA Climate Data Assimilation System (JRA-25/JCDAS) of Japan Meteorological Agency [Onogi et al., 2007] was used for 3D field of meteorological variables for the calculation. As a validation, the model was compared with two others, namely, Meteorological Data Explorer of the Center for Global Environmental Reserch (METEX/CGER) [Zeng et al., 2003], and the trajectory model of the National Institute of Polar Research (NIPR) [Tomikawa and Sato, 2005]. The comparison found that model results are fairly robust within 5 days from the computational start, i.e., the end of the trajectory, regardless of different datasets and different schemes employed in these models. Then, the back-trajectory model was applied to the observed precipitation at the target site, a surface station in northern Mongolia called Kherlenbayan-Ulaan(KBU), where highly accurate and temporarily dense precipitation measurements are available. Back trajectory lines were calculated for each of the observed precipitation during the warm season of the years 2003 to 2009, on the isentropic surfaces of 300K, 310K and 320K where the highest value of water vapor is observed. The results show that, in general, the back trajectory lines spread toward the north and the west region of the target site. This indicates that, the source regions of water vapor precipitated at KBU are located in the region which includes central Asia and Siberia, toward the Atlantic Ocean and the Arctic Ocean. This is consistent with the result of previous study [Sato et al., 2007], which used a regional climate model (RCM). It was found that the year 2003 had a significant difference from the other years in the following points: In this year 2003, 1) the total precipitation was anomalously large, 2) the number of trajectory lines traveling from the north was larger than in the other years, 3) the value of specific humidity above KBU tended to be higher with the northern trajectory lines than with the western trajectory lines, and finally, 4) the amount of precipitation associated with the northern trajectory lines was larger than that in other years. From these results, it can be hypothesized that with the more trajectory lines traveling from the north the more water vapor was brought and caused larger precipitation during the warm season at the northern Mongolia.

Koike, Y.; Asanuma, J.

2012-12-01

267

Numerical modeling of water injection into vapor-dominatedgeothermal reservoirs  

SciTech Connect

Water injection has been recognized as a powerful techniquefor enhancing energy recovery from vapor-dominated geothermal systemssuch as The Geysers. In addition to increasing reservoir pressures,production well flow rates, and long-term sustainability of steamproduction, injection has also been shown to reduce concentrations ofnon-condensible gases (NCGs) in produced steam. The latter effectimproves energy conversion efficiency and reduces corrosion problems inwellbores and surface lines.This report reviews thermodynamic andhydrogeologic conditions and mechanisms that play an important role inreservoir response to water injection. An existing general-purposereservoir simulator has been enhanced to allow modeling of injectioneffects in heterogeneous fractured reservoirs in three dimensions,including effects of non-condensible gases of different solubility.Illustrative applications demonstrate fluid flow and heat transfermechanisms that are considered crucial for developing approaches to insitu abatement of NCGs.

Pruess, Karsten

2006-11-06

268

Generation and characterization of aerosols and vapors for inhalation experiments.  

PubMed Central

Control of aerosol and vapor characteristics that affect the toxicity of inhaled contaminants often determines the methods of generating exposure atmospheres. Generation methods for aerosols and vapors are presented. The characteristics of the resulting exposure atmosphere and the limitations of the various generation methods are discussed. Methods and instruments for measuring the airborne contaminant with respect to various charcteristics are also described. PMID:797565

Tillery, M I; Wood, G O; Ettinger, H J

1976-01-01

269

Alumina Volatility in Water Vapor at Elevated Temperatures: Application to Combustion Environments  

NASA Technical Reports Server (NTRS)

The volatility of alumina in high temperature water vapor was determined by measuring weight loss of sapphire coupons at temperatures between 1250 and 1500 C, water vapor partial pressures between 0.15 and 0.68 atm in oxygen, at one atmosphere total pressure, and a gas velocity of 4.4 centimeters per second. The variation of the volatility with water vapor partial pressure was consistent with Al(OH)3(g) formation. The enthalpy of reaction to form Al(OH)3(g) from alumina and water vapor was found to be 210 plus or minus 20 kJ/mol. Surface rearrangement of ground sapphire surfaces increased with water vapor partial pressure, temperature and volatility rate. Recession rates of alumina due to volatility were determined as a function of water vapor partial pressure and temperature to evaluate limits for use of alumina in long term applications in combustion environments.

Opila, Elizabeth J.; Myers, Dwight L.

2003-01-01

270

Raman lidar profiling of atmospheric water vapor: Simultaneous measurements with two collocated systems  

NASA Technical Reports Server (NTRS)

Raman lidar is a leading candidate for providing the detailed space- and time-resolved measurements of water vapor needed by a variety of atmospheric studies. Simultaneous measurements of atmospheric water vapor are described using two collocated Raman lidar systems. These lidar systems, developed at the NASA/Goddard Space Flight Center and Sandia National Laboratories, acquired approximately 12 hours of simultaneous water vapor data during three nights in November 1992 while the systems were collocated at the Goddard Space Flight Center. Although these lidar systems differ substantially in their design, measured water vapor profiles agreeed within 0.15 g/kg between altitudes of 1 and 5 km. Comparisons with coincident radiosondes showed all instruments agreed within 0.2 g/kg in this same altitude range. Both lidars also clearly showed the advection of water vapor in the middle troposphere and the pronounced increase in water vapor in the nocturnal boundary layer that occurred during one night.

Goldsmith, J. E. M.; Bisson, Scott E.; Ferrare, Richard A.; Evans, Keith D.; Whiteman, David N.; Melfi, S. H.

1994-01-01

271

Global Seasonal Variation of Water Vapor on Mars and the Implications for Permafrost  

Microsoft Academic Search

Observations of the global distribution and seasonal variation of the Martian atmospheric water vapor have been made from the Viking orbiters for a continuous period covering a complete Martian year. The seasonal dependence of the latitude distribution of the column abundance of vapor is consistent with a model in which the vapor is in equilibrium with the regolith at polar

C. B. Farmer; P. E. Doms

1979-01-01

272

Cold Water Vapor in the Barnard 5 Molecular Cloud  

E-print Network

After more than 30 years of investigations, the nature of gas-grain interactions at low temperatures remains an unresolved issue in astrochemistry. Water ice is the dominant ice found in cold molecular clouds, however, there is only one region where cold (~10 K) water vapor has been detected - L1544. This study aims to shed light on ice desorption mechanisms under cold cloud conditions by expanding the sample. The clumpy distribution of methanol in dark clouds testifies to transient desorption processes at work -- likely to also disrupt water ice mantles. Therefore, the Herschel HIFI instrument was used to search for cold water in a small sample of prominent methanol emission peaks. We report detections of the ground-state transition of o-H2O (J = 1_10 - 1_01) at 556.9360 GHz toward two positions in the cold molecular cloud Barnard 5. The relative abundances of methanol and water gas support a desorption mechanism which disrupts the outer ice mantle layers, rather than causing complete mantle removal.

Wirström, E S; Persson, C M; Buckle, J V; Cordiner, M A; Takakuwa, S

2014-01-01

273

Cold Water Vapor in the Barnard 5 Molecular Cloud  

NASA Astrophysics Data System (ADS)

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

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

2014-06-01

274

Formation and Survival of Water Vapor in the Terrestrial Planet-Forming Region  

Microsoft Academic Search

Recent astronomical observations have revealed what may prove to be the ubiquity of water vapor during the early stages of planet formation. We present here a simple mechanism showing how water vapor forms in situ and is capable of shielding itself from molecule-destroying stellar radiation. The absorption of this radiation by water can control the thermodynamics of the terrestrial planet-forming

Thomas Bethell; Edwin Bergin

2009-01-01

275

Numerical Analysis of Coupled Water, Vapor, and Heat Transport in the Vadose Zone  

Microsoft Academic Search

Vapor movement is often an important part in the total water flux in the vadose zone of arid or semiarid regions because the soil moisture is relatively low. The two major objectives of this study were to develop a numerical model in the HYDRUS-1D code that (i) solves the coupled equations governing liquid water, water vapor, and heat transport, together

Hirotaka Saito; Jiri Šim?nek; Binayak P. Mohanty

2006-01-01

276

Reaction kinetics for the high temperature oxidation of Pu1wt%Ga in water vapor  

Microsoft Academic Search

Oxidation of plutonium metal is greatly accelerated by the presence of water vapor. The magnitude of the effect of water vapor on oxidation kinetics is determined by temperature, water concentration, and oxygen concentration. Most of the previous work has been directed toward evaluating the effect of moisture on the atmospheric oxidation of plutonium. Work on the isolation and characterization of

J. L. Stakebake; M. A. Saba

1988-01-01

277

TES/Aura L2 Water Vapor (H2O) Limb (TL2H2OL)  

TES/Aura L2 Water Vapor (H2O) Limb (TL2H2OL) News:  TES News ... Level:  L2 Platform:  TES/Aura L2 Water Vapor Spatial Coverage:  27 x 23 km Limb ... Access: OPeNDAP Parameters:  H2O Water Volume Mixing Radio Precision Vertical Resolution Order ...

2014-08-04

278

Water Vapor in the Protoplanetary Disk of DG Tau  

NASA Astrophysics Data System (ADS)

Water is key in the evolution of protoplanetary disks and the formation of comets and icy/water planets. While high excitation water lines originating in the hot inner disk have been detected in several T Tauri stars (TTSs), water vapor from the outer disk, where most of water ice reservoir is stored, was only reported in the closeby TTS TW Hya. We present spectrally resolved Herschel/HIFI observations of the young TTS DG Tau in the ortho- and para- water ground-state transitions at 557, 1113 GHz. The lines show a narrow double-peaked profile, consistent with an origin in the outer disk, and are 19-26 times brighter than in TW Hya. In contrast, CO and [C II] lines are dominated by emission from the envelope/outflow, which makes H2O lines a unique tracer of the disk of DG Tau. Disk modeling with the thermo-chemical code ProDiMo indicates that the strong UV field, due to the young age and strong accretion of DG Tau, irradiates a disk upper layer at 10-90 AU from the star, heating it up to temperatures of 600 K and producing the observed bright water lines. The models suggest a disk mass of 0.015-0.1 Msun, consistent with the estimated minimum mass of the solar nebula before planet formation, and a water reservoir of 1e2-1e3 Earth oceans in vapour, and 100 times larger in the form of ice. Hence, this detection supports the scenario of ocean delivery on terrestrial planets by impact of icy bodies forming in the outer disk.

Podio, Linda; Kamp, Inga; Codella, Claudio; Cabrit, Sylvie; Nisini, Brunella; Dougados, Catherine; Sandell, Goran; Williams, Jonathan P.; Testi, Leonardo; Thi, Wing-Fai; Woitke, Peter; Meijerink, Rowin; Spaans, Marco; Aresu, Giambattista; Ménard, Francois; Pinte, Christophe

2013-07-01

279

First-time lidar measurement of water vapor flux in a volcanic plume  

NASA Astrophysics Data System (ADS)

The CO2 laser-based lidar ATLAS has been used to study the Stromboli volcano plume. ATLAS measured water vapor concentration in cross-sections of the plume and wind speed at the crater. Water vapor concentration and wind speed were retrieved by differential absorption lidar and correlation technique, respectively. Lidar returns were obtained up to a range of 3 km. The spatial resolution was 15 m and the temporal resolution was 20 s. By combining these measurements, the water vapor flux in the Stromboli volcano plume was found. To our knowledge, it is the first time that lidar retrieves water vapor concentrations in a volcanic plume.

Fiorani, Luca; Colao, Francesco; Palucci, Antonio; Poreh, Davod; Aiuppa, Alessandro; Giudice, Gaetano

2011-03-01

280

Prediction of water vapor transport rates across polyvinylchloride packaging systems using a novel radiotracer method  

SciTech Connect

A radiotracer method is used to study the transport properties of water vapor in polyvinylchloride (PVC), a plastic commonly used in the packaging of parenteral solutions. Water vapor transport across a PVC film appears to be Fickian in nature. Using the steady-state solution of Fick's second law and the permeability coefficient of water vapor across the PVC film obtained using the described method, the predicted water vapor transport rate (WVTR) for a parenteral solution packaged in PVC is in reasonable agreement with actual WVTR as determined by weight loss under precisely controlled conditions.

Wood, R.W.; Mulski, M.J.; Kuu, W.Y. (Baxter Healthcare Corporation, Round Lake, IL (USA))

1990-09-01

281

The annual cycle of stratospheric water vapor in a general circulation model  

NASA Technical Reports Server (NTRS)

The application of general circulation models (GCM's) to stratospheric chemistry and transport both permits and requires a thorough investigation of stratospheric water vapor. The National Center for Atmospheric Research has redesigned its GCM, the Community Climate Model (CCM2), to enable studies of the chemistry and transport of tracers including water vapor; the importance of water vapor to the climate and chemistry of the stratosphere requires that it be better understood in the atmosphere and well represented in the model. In this study, methane is carried as a tracer and converted to water; this simple chemistry provides an adequate representation of the upper stratospheric water vapor source. The cold temperature bias in the winter polar stratosphere, which the CCM2 shares with other GCM's, produces excessive dehydration in the southern hemisphere, but this dry bias can be ameliorated by setting a minimum vapor pressure. The CCM2's water vapor distribution and seasonality compare favorably with observations in many respects, though seasonal variations including the upper stratospheric semiannual oscillation are generally too small. Southern polar dehydration affects midlatitude water vapor mixing ratios by a few tenths of a part per million, mostly after the demise of the vortex. The annual cycle of water vapor in the tropical and northern midlatitude lower stratosphere is dominated by drying at the tropical tropopause. Water vapor has a longer adjustment time than methane and had not reached equilibrium at the end of the 9 years simulated here.

Mote, Philip W.

1995-01-01

282

Convective transport of water vapor into the lower stratosphere observed during double-tropopause events  

NASA Astrophysics Data System (ADS)

We present in situ observations of convectively injected water vapor in the lower stratosphere from instruments aboard two aircraft operated during the Deep Convective Clouds and Chemistry experiment. Water vapor mixing ratios in the injected air are observed to be 60-225 ppmv at altitudes 1-2 km above the tropopause (350-370 K potential temperature), well above observed background mixing ratios of 5-10 ppmv in the lower stratosphere. Radar observations of the responsible convective systems show deep overshooting at altitudes up to 4 km above the lapse rate tropopause and above the flight ceilings of the aircraft. Backward trajectories from the in situ observations show that convectively injected water vapor is observed from three distinct types of systems: isolated convection, a convective line, and a leading line-trailing stratiform mesoscale convective system. Significant transport of additional tropospheric or boundary layer trace gases is observed only for the leading line-trailing stratiform case. In addition, all observations of convective injection are found to occur within large-scale double-tropopause events from poleward Rossby wave breaking. Based on this relationship, we present a hypothesis on the role of the large-scale lower stratosphere during convective overshooting. In particular, the reduced lower stratosphere stability associated with double-tropopause environments may facilitate deeper levels of overshooting and convective injection.

Homeyer, Cameron R.; Pan, Laura L.; Dorsi, Samuel W.; Avallone, Linnea M.; Weinheimer, Andrew J.; O'Brien, Anthony S.; DiGangi, Joshua P.; Zondlo, Mark A.; Ryerson, Thomas B.; Diskin, Glenn S.; Campos, Teresa L.

2014-09-01

283

CRISTA-NF measurements of water vapor during the SCOUT-O3 Tropical Aircraft Campaign  

NASA Astrophysics Data System (ADS)

The new remote sensing experiment CRISTA-NF (Cryogenic Infrared Spectrometers and Telescopes for the Atmosphere New Frontiers) successfully participated in the SCOUT-O3 Tropical Aircraft Campaign in November and December 2005. CRISTA-NF operated aboard the high-altitude research aircraft M-55 Geophysica. Mid-infrared spectra (4 15 ?m) were measured in the limb sounding geometry with high spatial resolution (250 m vertical sampling, 5 15 km along track sampling). Measurements were carried out during transfer flights between Oberpfaffenhofen, Germany, and Darwin, Australia, as well as during several local flights near Darwin. Water vapor volume mixing ratios in the upper troposphere and lower stratosphere were derived from the CRISTA-NF radiance measurements by utilizing a rapid radiative transfer forward model and the optimal estimation retrieval approach. CRISTA-NF water vapor measurements below the hygropause have a total retrieval error of 15 40% (i.e. root mean square of accuracy and precision). The systematic terms are dominating in the retrieval error budget. The contributions of a priori information to the retrieval results are less than 5 10%. The vertical resolution of the observations is about 250 500 m when permitted by instrument sampling. In this paper we present first results for three transfer flights of the campaign. Being generally in good agreement with corresponding ECMWF operational analyzes, the CRISTA-NF measurements show significantly higher variability and local structures in the upper tropospheric water vapor distributions.

Hoffmann, L.; Weigel, K.; Spang, R.; Schroeder, S.; Arndt, K.; Lehmann, C.; Kaufmann, M.; Ern, M.; Preusse, P.; Stroh, F.; Riese, M.

2009-01-01

284

Continuous field measurements of ?D in water vapor by open-path Fourier transform infrared spectrometry  

NASA Astrophysics Data System (ADS)

The stable isotopes in atmospheric water vapor contain rich information on the hydrologic cycles and gaseous exchange processes between biosphere and atmosphere. About one-week field experiment was conducted to continuously measure the isotope composition of water vapor in ambient air using an open-path FTIR system. Mixing ratios of H2 16O and HD16O were measured simultaneously. Analysis of water vapor isotopes revealed that the variations of H2 16O and HD16O were highly related. Mixing ratios of both isotopes varied considerably on a daily timescale or between days, with no obvious diurnal cycle, whereas the deuterium isotopic [delta]D showed clear diel cycle. The results illustrated that the correlation between [delta]D and H2O mixing ratio was relatively weak, which was also demonstrated by the Keeling plot analysis with the whole data. Yet the further Keeling analysis on a daily timescale displayed more obvious linear relationship between [delta]D and the total H2O concentration. All daily isotopic values of evapotranspiration source were obtained, with the range between -113.93±10.25‰ and -245.63±17.61‰ over the observation period.

Wang, Wei; Liu, Wenqing; Zhang, Tianshu

2012-12-01

285

The diel cycle of water vapor in west Greenland  

NASA Astrophysics Data System (ADS)

present a study of the dynamics of small-scale (~100 km) atmospheric circulation in west Greenland which is dominated by interactions of marine and continental air masses. Water vapor concentration and isotopic ratios measured continuously over a 25 day period in Kangerlussuaq, Greenland were used to monitor the convergence of easterly katabatic winds and westerly sea breezes that form a front between the dry, isotopically depleted, glacial air mass and the moist, isotopically enriched, marine air mass. During the latter 16 days of the measurement period, an interval with no large-scale synoptic interference, the inland penetration of the sea breeze controlled the largest day-to-day humidity and vapor isotopic variations. Kangerlussuaq experienced sea breezes in the afternoon on 9 days, consistent with the long-term average of such occurrences on 56% of days in July and August. The inland position of the sea breeze front is controlled by the katabatic wind strength, which is stronger during times of reduced cloud coverage and/or higher-pressure gradient between the coast and the Greenland ice sheet. The position and movement of the front will likely respond to changes in the general atmospheric circulation and regional radiation balance resulting from global warming, which will, in turn, impact the local hydrological cycle and ecosystem processes.

Kopec, B. G.; Lauder, A. M.; Posmentier, E. S.; Feng, X.

2014-08-01

286

Europa's Water Vapor Plumes: Systematically Constraining their Abundance and Variability  

NASA Astrophysics Data System (ADS)

The discovery of transient water vapor plumes near Europa's south pole (Roth et al. 2014) has important implications for the search for life in our Solar System. Europa's subsurface water ocean is thought to provide all the ingredients needed for a habitable environment. The plumes might enable direct sampling of Europa's subsurface constituents and provide insights into the chemistry, mobility, and extent of the liquid water environments. In STIS spectral images obtained in Dec. 2012, the intensity ratios of atomic H and O auroral emissions uniquely identify the source as electron impact excitation of water molecules. However, a confirmation of the initial detection has not yet been achieved, and non-detections from four out of five previous such visits suggest a complex and possibly episodic variation in plume activity. We have identified five potential variability sources for plume activity and detectability and propose a focused program to systematically constrain Europa's plumes and their variability pattern. Our constraints for the plume activity on Europa are vital inputs for key programmatic decisions regarding NASA's next large mission to Europa.

Roth, Lorenz

2014-10-01

287

Condensed-phase transitions in binary systems during dynamic vaporization experiments. Effusion and transpiration  

SciTech Connect

During a condensed-phase transition at equilibrium in a vaporization experiment, three phases are present. In this paper, equations relating vapor pressure, temperature, and compositions of the vapor and condensed phases are derived for systems undergoing such transitions. Previously observed unusual phenomena, such as vapor pressures that increase at constant temperature and vapor pressures that increase with decreasing temperature, are explained. It is shown that equilibrium condensed-phase transitions in the presence of the vapor are always hysteretic in the temperature; the transition occurs at a higher temperature in the increasing-temperature direction than in the decreasing-temperature direction. The particular cases of effusion and transpiration experiments are treated in detail. 31 refs., 5 figs.

Edwards, J.G. [Univ. of Toledo, OH (United States); Franzen, H.F. [Ames Lab., IA (United States)

1995-03-30

288

Nuclear Quantum Effects Affect Bond Orientation of Water at the Water-Vapor Interface  

NASA Astrophysics Data System (ADS)

Using combined theoretical and experimental approaches, we demonstrate that the bond orientation of water at the water-vapor interface depends markedly on the water isotope (H-D) composition. While the interfacial water structures of H2O and D2O are indistinguishable, the intramolecular symmetry breaking in HDO is directly reflected at the surface: the OD bonds preferably orient down towards the bulk water, whereas the OH bond tends to orient up into the vapor phase. Path integral molecular dynamics simulations show good agreement with surface-specific sum-frequency generation (SFG) spectroscopy results, revealing that the distinct interfacial bond orientations originate from nuclear quantum effects. The enhanced localization of the heavier D atom leads to stronger hydrogen bonds, giving rise to OD bonds pointing down into the bulk.

Nagata, Yuki; Pool, Ruben E.; Backus, Ellen H. G.; Bonn, Mischa

2012-11-01

289

Treatment of Produced Waters Using a Surfactant Modified Zeolite/Vapor Phase Bioreactor System  

SciTech Connect

This report summarizes work of this project from October 2003 through March 2004. The major focus of the research was to further investigate BTEX removal from produced water, to quantify metal ion removal from produced water, and to evaluate a lab-scale vapor phase bioreactor (VPB) for BTEX destruction in off-gases produced during SMZ regeneration. Batch equilibrium sorption studies were conducted to evaluate the effect of semi-volatile organic compounds commonly found in produced water on the sorption of benzene, toluene, ethylbenzene, and xylene (BTEX) onto surfactant-modified zeolite (SMZ) and to examine selected metal ion sorption onto SMZ. The sorption of polar semi-volatile organic compounds and metals commonly found in produced water onto SMZ was also investigated. Batch experiments were performed in a synthetic saline solution that mimicked water from a produced water collection facility in Wyoming. Results indicated that increasing concentrations of semi-volatile organic compounds increased BTEX sorption. The sorption of phenol compounds could be described by linear isotherms, but the linear partitioning coefficients decreased with increasing pH, especially above the pKa's of the compounds. Linear correlations relating partitioning coefficients of phenol compounds with their respective solubilities and octanol-water partitioning coefficients were developed for data collected at pH 7.2. The sorption of chromate, selenate, and barium in synthetic produced water were also described by Langmuir isotherms. Experiments conducted with a lab-scale vapor phase bioreactor (VPB) packed with foam indicated that this system could achieve high BTEX removal efficiencies once the nutrient delivery system was optimized. The xylene isomers and benzene were found to require the greatest biofilter bed depth for removal. This result suggested that these VOCs would ultimately control the size of the biofilter required for the produced water application. The biofilter recovered rapidly from shutdowns showing that the system was resilient to discontinuous feed conditions therefore provided flexibility on the SMZ regeneration process.

Lynn E. Katz; Kerry A. Kinney; R. S. Bowman; E. J. Sullivan

2004-03-11

290

Global lower mesospheric water vapor revealed by LIMS observations  

NASA Technical Reports Server (NTRS)

The Limb Infrared Monitor of the Stratospheric water vapor channel data analysis has been extended from the 1. mb level (about 48 km) to the .3 mb level (about 60 km) through a radiance averaging procedure and better understanding of systematic errors. The data show H2O mixing ratio peaks near the .5 mb level varying from 4 to 7 ppmv with latitude and season. Above this level the mixing ratio drops off quickly with altitude, but, due to experimental uncertainties, at an uncertain rate. The stratospheric results are virtually the same as determined from the archived LIMS results with a tropical hygropause and enhanced H2O concentration in the lower levels at high winter latitudes.

Gordley, L. L.; Russell, J. M., III; Remsberg, E. E.

1985-01-01

291

Solar Mesosphere Explorer observations of stratospheric and mesospheric water vapor  

NASA Technical Reports Server (NTRS)

It is noted that while the SME (Solar Mesosphere Explorer) data is consistent with the earlier LIMS (Limb Infrared Monitor of the Stratosphere) results, its interpretation is complicated by aerosol contamination, particularly at altitudes below 35 km. This contamination arose from several volcanic eruptions, including that of El Chichon. Analyses are reported of a subset of data from the SME satellite, concentrating primarily on the period January through March 1982 so as to avoid contamination from the El Chichon volcanic aerosol. The SME observations of water vapor between 20 and 60 km were inverted for the first three months of 1982 as well as for selected additional periods. Reasonable results are obtained at locations where no contamination by aerosol is suspected.

Jakosky, Bruce M.; Thomas, Gary E.; Rusch, David W.; Barth, Charles A.; Lawrence, George M.; Olivero, John J.; Clancy, R. Todd; Sanders, Ryan W.; Knapp, Barry G.

1988-01-01

292

Computation of infrared cooling rates in the water vapor bands  

NASA Technical Reports Server (NTRS)

A fast but accurate method for calculating the infrared radiative terms due to water vapor has been developed. It makes use of the far wing approximation to scale transmission along an inhomogeneous path to an equivalent homogeneous path. Rather than using standard conditions for scaling, the reference temperatures and pressures are chosen in this study to correspond to the regions where cooling is most significant. This greatly increased the accuracy of the new method. Compared to line by line calculations, the new method has errors up to 4% of the maximum cooling rate, while a commonly used method based upon the Goody band model (Rodgers and Walshaw, 1966) introduces errors up to 11%. The effect of temperature dependence of transmittance has also been evaluated; the cooling rate errors range up to 11% when the temperature dependence is ignored. In addition to being more accurate, the new method is much faster than those based upon the Goody band model.

Chou, M. D.; Arking, A.

1978-01-01

293

Laboratory Measurements for the Water Vapor Continuum and Theoretical Calculations for the Water Vapor Foreign Continuum in the Terahertz Spectral Region  

NASA Astrophysics Data System (ADS)

We present a spectroscopic study of the water-vapor continuum absorption in the terahertz spectral region. The experimental technique combines a temperature stabilized multipass absorption cell, a polarizing (Martin-Puplett) interferometric spectrometer, and a liquid-He-cooled bolometer detector. The absorbance resulting from a pure water vapor, H2O—N2 mixture, and H2O—O2 mixture have been measured at terahertz windows in temperatures ranging from 293 to 333 K with spectral resolution of 0.04 to 0.12 cm?1. By subtracting local line contributions modeled with the HITRAN2004 database and a Van Vleck-Weisskopf lineshape function, the self- and foreign-continuum are derived from the measurements. By fitting continuum results obtained for each of these windows and for all windows into a simple formula, we have obtained parameterizations of the continuum applicable for individual windows and for all windows. Meanwhile, theoretically calculated foreign-continuum is also presented and reasonable agreement with experiment is achieved.

Podobedov, V. B.; Plusquellic, D. F.; Siegrist, K. M.; Fraser, G. T.; Ma, Q.; Tipping, R. H.

2009-03-01

294

Projected Regime Shift in Arctic Cloud and Water Vapor Feedbacks  

NASA Technical Reports Server (NTRS)

The Arctic climate is changing faster than any other large-scale region on Earth. A variety of positive feedback mechanisms are responsible for the amplification, most of which are linked with changes in snow and ice cover, surface temperature (T(sub s)), atmospheric water vapor (WV), and cloud properties. As greenhouse gases continue to accumulate in the atmosphere, air temperature and water vapor content also increase, leading to a warmer surface and ice loss, which further enhance evaporation and WV. Many details of these interrelated feedbacks are poorly understood, yet are essential for understanding the pace and regional variations in future Arctic change. We use a global climate model (Goddard Institute for Space Studies, Atmosphere-Ocean Model) to examine several components of these feedbacks, how they vary by season, and how they are projected to change through the 21st century. One positive feedback begins with an increase in T(sub s) that produces an increase in WV, which in turn increases the downward longwave flux (DLF) and T(sub s), leading to further evaporation. Another associates the expected increases in cloud cover and optical thickness with increasing DLF and T(sub s). We examine the sensitivities between DLF and other climate variables in these feedbacks and find that they are strongest in the non-summer seasons, leading to the largest amplification in Ts during these months. Later in the 21st century, however, DLF becomes less sensitive to changes in WV and cloud optical thickness, as they cause the atmosphere to emit longwave radiation more nearly as a black body. This regime shift in sensitivity implies that the amplified pace of Arctic change relative to the northern hemisphere could relax in the future.

Chen, Yonghua; Miller, James R.; Francis, Jennifer; Russel, Gary L.

2011-01-01

295

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

PubMed

Recent astronomical observations have revealed what may prove to be the ubiquity of water vapor during the early stages of planet formation. We present here a simple mechanism showing how water vapor forms in situ and is capable of shielding itself from molecule-destroying stellar radiation. The absorption of this radiation by water can control the thermodynamics of the terrestrial planet-forming zone. Similar to Earth's ozone layer, which shelters the chemistry of life, the water layer protects other water molecules and allows for a rich organic chemistry. The total abundance of water vapor in the natal habitable zone is equal to that of several thousand oceans. PMID:20019283

Bethell, Thomas; Bergin, Edwin

2009-12-18

296

MM-Wave Radiometric Measurements of Low Amounts of Precipitable Water Vapor  

NASA Technical Reports Server (NTRS)

An experiment was conducted during March, 1999 to study ways in which to improve techniques for measuring low amounts of total-column precipitable water vapor (PWV). The experiment was conducted at the DOE's ARM program's North Slope of Alaska/Adjacent Arctic Ocean Cloud and Radiation Testbed site (DoE ARM NSA/AAO CaRT) located just outside Barrow, Alaska. NASA and NOAA deployed a suite of radiometers covering 25 channels in the frequency range of 20 GHz up to 340 GHz including 8 channels around the 183 GHz water vapor absorption line. In addition to the usual CaRT site instrumentation the NOAA Depolarization and Backscatter Unattended Lidar (DABUL), the SUNY Rotating Shadowband Spectroradiometer (RSS) and other surface based meteorological instrumentation were deployed during the intensive observation period. Vaisala RS80 radiosondes were launched daily as well as nearby National Weather Service VIZ sondes. Atmospheric conditions ranged from clear calm skies to blowing snow and heavy multi-layer cloud coverage. Measurements made by the radiosondes indicate the PWV varied from approx. 1 to approx. 5 mm during the experiment. The near-surface temperature varied between about -40 C to - 15 C. In this presentation, an overview of the experiment with examples of data collected will be presented. Application of the data for assessing the potential and limitations of millimeter-wave radiometry for retrieving very low amounts of PWV will be discussed.

Racette, P.; Westwater, Ed; Han, Yong; Manning, Will; Jones, David; Gasiewski, Al

2000-01-01

297

Estimation of Precipitable Water Vapor Using the GPS  

NASA Astrophysics Data System (ADS)

The radio waves transmitted from GPS satellites is delayed by the troposphere as they propagate to Earth-based GPS receivers. The troposphere delay is usually divided into two parts, the dry delay due to the atmospheric gases and the wet delay due to the water vapor. In this study for the month of May in 1998 the GPS data from two stations(Taejon, Suwon) were used to estimate the total troposphere delay in the zenith direction by the least square method. The dry delay in the zenith direction can be evaluated by using surface pressure values at the station, then the zenith wet delay is obtained by removing the zenith dry delay from the total delay. The zenith wet delay is strongly correlated with the total precipitable water. The quality of the estimate has been assessed by comparison with radiosonde data at Osan. We found the good agreement in precipitable water of the GPS estimates and the radiosonde data. The standard deviation of the difference between the GPS and radiosonde observations was 3.68mm at Suwon.

Moon, Yong-Jin; Choi, Kyu-Hong; Park, Pil-Ho

1999-06-01

298

Transparent and robust siloxane-based hybrid lamella film as a water vapor barrier coating.  

PubMed

Water vapor barriers are important in various application fields, such as food packaging and sealants in electronic devices. Polymer/clay composites are well-studied water vapor barrier materials, but their transparency and mechanical strength degrade with increasing clay loading. Herein, we demonstrate films with good water vapor barrier properties, high transparency, and mechanical/thermal stability. Water vapor barrier films were prepared by the solution crystallization of siloxane hybrid lamellae. The films consist of highly crystallized organic/inorganic hybrid lamellae, which provide high transparency, hardness, and thermal stability and inhibit the permeation of water vapor. The water permeability of a 6 ?m thick hybrid film is comparable to that of a 200 ?m thick silicon rubber film. PMID:25296395

Tokudome, Yasuaki; Hara, Takaaki; Abe, Risa; Takahashi, Masahide

2014-11-12

299

Water Vapor Variations over Mauna Loa and Table Mountain since 2010  

NASA Astrophysics Data System (ADS)

The Vapor Millimeter-wave Spectrometer (WVMS) instrument deployed at Network for the Detection of Atmospheric Composition Change (NDACC) sites at Table Mountain, California (34.4N, 242.3E) and at Mauna Loa, Hawaii (19.5N, 204.4E) have, since 2010, been able to make measurements down to ~26km. With this extended retrieval capability these instruments can now make measurements from ~26-80km. There is an increase from 2010 to 2012 which appears to be caused primarily by dynamical variations, although an increase in water vapor entering the stratosphere probably also plays a role at the lower altitudes. Water vapor mixing ratios at both of these NDACC sites are now higher than they have been for about a decade from the lower stratosphere through the mid-mesosphere. In addition to the WVMS measurements, we will present coincident satellite measurements from the Aura Microwave Limb Sounder (MLS), the Atmospheric Chemistry Experiment (ACE), and the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS). We will also compare the lowest altitude WVMS measurements with frostpoint hygrometer measurements from Boulder, Colorado (40N, 255E), and Hilo, Hawaii (19.7N, 205E). In order to understand the interannual dynamically-driven changes in water vapor, we will investigate interannual variations in mixing using equivalent length and tracer equivalent latitude from 2010-2012. Since dynamical variations affect H2O in the stratosphere primarily by changing the amount of CH4 oxidation that has occurred in a particular region, we will also examine CH4 variations from the GMI model.

Nedoluha, G. E.; Gomez, R. M.; Allen, D. R.; Boone, C.; Lambert, A.; Stiller, G. P.; Hurst, D. F.

2012-12-01

300

Description of data on the Nimbus 7 LIMS map archive tape: Water vapor and nitrogen dioxide  

NASA Technical Reports Server (NTRS)

Described is the process by which the analysis of the Limb Infrared Monitor of the Stratosphere (LIMS) experiment data were used to produce estimates of synoptic maps of water vapor and nitrogen dioxide. In addition to a detailed description of the analysis procedure, also discussed are several interesting features in the data which are used to demonstrate how the analysis procedure produced the final maps and how one can estimate the uncertainties in the maps. In addition, features in the analysis are noted that would influence how one might use, or interpret, the results. These include subjects such as smoothing and the interpretation of wave components.

Haggard, Kenneth V.; Marshall, B. T.; Kurzeja, Robert J.; Remsberg, Ellis E.; Russell, James M., III

1988-01-01

301

Atmospheric water vapor transport associated with typical anomalous summer rainfall patterns in China  

Microsoft Academic Search

This paper attempts to reveal the atmospheric water vapor transports associated with typical anomalous summer rainfall patterns in China. The results show that origins of water vapor supply related to anomalous rainfall patterns are different from those related to the normal monsoon rainfall. Anomalous pattern 1, with a heavier rainbelt along the middle and lower reaches of the Yangtze River

Tian-Jun Zhou; Ru-Cong Yu

2005-01-01

302

Adsorption of water vapor and carbon dioxide at carboxylic functional groups on the surface of coal  

Microsoft Academic Search

The adsorption of water vapor and carbon dioxide at room temperature in relation to carboxylic functional groups on the surfaces of 20 different types of coal was examined.The carboxylic functional groups on the surface of coal may be considered the preferential sites of adsorption when compared with the other groups. The adsorption of water vapor and carbon dioxide was found

J Nishino

2001-01-01

303

CORONA DISCHARGE EFFECTS IN GAS-SOLID ADSORPTION: WATER VAPOR ON SILICA GEL AND FLY ASH  

Microsoft Academic Search

Equilibrium characteristics of water vapor adsorption on microporous silica gel and macroporous fly ash are investigated in the presence of corona discharges. The discharge is produced at a fine wire surface in a wire-cylinder electrode geometry, with the adsorbent sample placed in the inter-electrode space. A significant reduction in water vapor adsorption capacity is observed for both negative and positive

A. V. SOMESHWAR; D. L. PESHORI

1987-01-01

304

Determination of the water vapor continuum absorption by THz-TDS and Molecular  

E-print Network

Determination of the water vapor continuum absorption by THz-TDS and Molecular Response Theory: Determination of the water vapor continuum absorption from 0.35 to 1 THz is reported. The THz pulses propagate though a 137 m long humidity-controlled chamber and are measured by THz time-domain spectroscopy (THz

Oklahoma State University

305

Global Cooling After the Eruption of Mount Pinatubo: A Test of Climate Feedback by Water Vapor  

Microsoft Academic Search

The sensitivity of Earth's climate to an external radiative forcing depends critically on the response of water vapor. We use the global cooling and drying of the atmosphere that was observed after the eruption of Mount Pinatubo to test model predictions of the climate feedback from water vapor. Here, we first highlight the success of the model in reproducing the

Brian J. Soden; Richard T. Wetherald; Georgiy L. Stenchikov; Alan Robock

2002-01-01

306

An Analysis of Cloud Cover and Water Vapor for the ALMA Project  

E-print Network

and water vapor at Chajnantor (Chile), Chalviri (Bolivia) and four sites in Argentina. Since timeAn Analysis of Cloud Cover and Water Vapor for the ALMA Project: A Comparison Between Chajnantor (Chile), Chalviri (Bolivia) and Five Sites in Argentina using Satellite Data and a Verification

307

Understanding the Changes of Stratospheric Water Vapor in Coupled Chemistry–Climate Model Simulations  

Microsoft Academic Search

Past and future climate simulations from the Goddard Earth Observing System Chemistry-Climate Model (GEOS CCM), with specified boundary conditions for sea surface temperature, sea ice, and trace gas emissions, have been analyzed to assess trends and possible causes of changes in stratospheric water vapor. The simulated distribution of stratospheric water vapor in the 1990s compares well with observations. Changes in

Luke Oman; Darryn W. Waugh; Steven Pawson; Richard S. Stolarski; J. Eric Nielsen

2008-01-01

308

Water vapor distribution measured in the middle atmosphere with an airborne microwave radiometer  

NASA Astrophysics Data System (ADS)

Stratospheric and mesospheric water vapor was measured with an airborne microwave radiometer at 183 GHz as part of the Cold Arctic Mesopause mission. Two water vapor profiles are presented. Due to technical problems with the spectrum analyzers measurement accuracy is much reduced, but the profiles are consistent with measurements made over the Pacific Ocean.

Kunzi, K. F.; Lobsiger, E.; Hartmann, G. K.

1983-06-01

309

The formation of molecular hydrogen through photolysis of water vapor in the presence of oxygen  

Microsoft Academic Search

1. A light source was constructed for the investigation of the photolysis of water vapor. A xenon discharge arc of a pressure of about 50 mm in a thin wall quartz tubing was used. 2. Molecular hydrogen formed from water vapor in the presence of other gases was measured by employing tritium as a tracer. A vacuum system was constructed,

Charles A. Barth; Hans E. Suess

1960-01-01

310

Pointed water vapor radiometer corrections for accurate Global Positioning System surveying  

Microsoft Academic Search

Delay of the Global Positioning System (GPS) signal due to atmospheric water vapor is a major source of error in GPS surveying. Improved vertical accuracy is important for sea level and polar isostasy measurements, geodesy, normal fault motion, subsidence, earthquake studies, air and ground-based gravimetry, ice dynamics, and volcanology. We conducted a GPS survey using water vapor radiometers (WVRs) pointed

Randolph Ware; Christian Rocken; Fredrick Solheim; Teresa Van Hove; Chris Alber; James Johnson

1993-01-01

311

Water vapor depletion in the DMT Continuous Flow CCN Chamber: effects on supersaturation and droplet growth.  

E-print Network

Water vapor depletion in the DMT Continuous Flow CCN Chamber: effects on supersaturation #12;1 Water vapor depletion in the DMT Continuous Flow CCN Chamber: effects on supersaturation of polydisperse calibration aerosol (with a DMT CFSTGC operated in constant flow mode) are used to evaluate

Nenes, Athanasios

312

Geodesy by radio interferometry: Water vapor radiometry for estimation of the wet delay  

Microsoft Academic Search

An important source of error in very-long-baseline interferometry (VLBI) estimates of baseline length is unmodeled variations of the refractivity of the neutral atmosphere along the propagation path of the radio signals. The authors present and discuss the method of using data from a water vapor readiometer (WVR) to correct for the propagation delay caused by atmospheric water vapor, the major

G. Elgered; J. L. Davis; T. A. Herring; I. I. Shapiro

1991-01-01

313

GPS Meteorology: Remote Sensing of Atmospheric Water Vapor Using the Global Positioning System  

Microsoft Academic Search

We present a new approach to remote sensing of water vapor based on the global positioning system (GPS). Geodesists and geophysicists have devised methods for estimating the extent to which signals propagating from GPS satellites to ground-based GPS receivers are delayed by atmospheric water vapor. This delay is parameterized in terms of a time-varying zenith wet delay (ZWD) which is

Michael Bevis; Steven Businger; Thomas A. Herring; Christian Rocken; Richard A. Anthes; Randolph H. Ware

1992-01-01

314

Measurements of water vapor in the middle atmosphere and implications for mesospheric transport  

Microsoft Academic Search

We present data obtained during more than 3 years of nearly continuous measurements of middle atmospheric water vapor. The data are obtained from ground-based measurements at 22 GHz taken at two sites, one in each hemisphere, using the Naval Research Laboratory water vapor millimeter-wave spectrometer (WVMS). With the construction of a second instrument, it has been possible to maintain continuous

Gerald E. Nedoluha; Richard M. Bevilacqua; R. Michael Gomez; William B. Waltman; Brian C. Hicks; D. L. Thacker; W. Andrew Matthews

1996-01-01

315

Accuracy and calibration considerations for ground based sensing of water vapor in the stratosphere and mesosphere  

SciTech Connect

The Water Vapor Monitoring System (WVMS) is a ground based broad band microwave (22.235 GHz) radiometer that analyzes emission spectra from the mesosphere to determine water vapor mixing ratios. This paper emphasizes the technical details of the instrument, experimental techniques, comparison of alternate techniques, and especially accuracy and calibration issues.

Thacker, D.L. [Interferometrics, Inc., Vienna, VA (United States); Bevilacqua, R.M.; Waltman, W.B. [Naval Research Lab., Washington, DC (United States)] [and others

1994-12-31

316

Evaluation of the Water Vapor Transport over the Yellow River Basin in CMIP5 Models  

NASA Astrophysics Data System (ADS)

Temperature, precipitation and water vapor transport in China, particularly in the Yellow River Basin simulated by the 16 models participating in phase 5 of the Coupled Model Inter-comparison Project (CMIP5) were evaluated for the period 1979-2005. Results suggest that most CMIP5 models are able to capture the climatological distribution patterns and inter-annual variations of surface air temperature, but with cold bias. Most models reproduce the spatial distribution pattern of warming trends identical with observations. Models tend to overestimate precipitation with relative biases ranging from 4.59 % to 61.46 %. Compared with observations, most models simulate more precipitation over the east of Tibetan Plateau and less in southeastern coastal regions. The spatial distribution of precipitation trends displayed in the observations cannot be well simulated by most models. The underestimation of temperature and the overestimation of precipitation simulated by some models over the east of Tibetan Plateau may be related to the anomalously strong western Pacific subtropical high and sufficient water vapor transport from Indian Ocean and western Pacific Ocean. In terms of the Yellow River Basin, modeled water vapor mainly flows in from eastern boundary and out from the western boundary. Water vapor also flows in through the southern boundary, but with smaller intensity. Owing to the overestimation of water vapor convergence, some models tend to exaggerate the climatological precipitation. Additionally, we found that the summer water vapor budget and precipitation keep pace with each other, which is well reflected by the FIO-ESM model. Models can also reproduce this relation in the lower reaches, with the total water vapor budget correlated strongly with water vapor transport from eastern, western and southern boundaries, indicating that water vapor budget and even the precipitation are strongly influenced by the water vapor transport from Indian Ocean and western Pacific Ocean. This situation is almost similar to the middle reaches, though the total water vapor budget is only related to water vapor transport from eastern and western boundaries, which mainly come from Indian Ocean. Nonetheless, in the upper reaches of the Yellow River Basin most models substantially underestimate the great contribution of water vapor transport from eastern and western boundaries, but overestimate the one from southern boundary, indicating that most models strongly overestimate the water vapor transport from the western Pacific Ocean which needs further improvement.

Bao, Jiawei; Feng, Jinming

2014-05-01

317

Radiative cooling by stratospheric water vapor: Big differences in GCM results  

NASA Astrophysics Data System (ADS)

The stratosphere has been cooling by about 2K/decade at 30-60 km over the past several decades and by lesser amounts toward the tropopause. Climate model calculations suggest that stratospheric water vapor is an important contributor to the observed stratospheric cooling, but there are large differences among recent GCM simulations for prescribed changes in stratospheric water vapor, which point to problems with the current GCM treatment of the absorption and emission by stratospheric water vapor. We show that the correlated k-distribution treatment with sufficient resolution is capable of simulating accurately cooling by stratospheric water vapor. We obtain equilibrium cooling of about 0.3K that extends from 20 km to the top of the atmosphere, and adjusted radiative forcing of 0.12 Wm-2, for a stratospheric water vapor increase of 0.7 ppmv which has been estimated for the period 1979-1997.

Oinas, V.; Lacis, A. A.; Rind, D.; Shindell, D. T.; Hansen, J. E.

318

Infrared Water Vapor Continuum Absorption: New Atmospheric Electrical Measurements and Theory.  

National Technical Information Service (NTIS)

The infrared (IR) continuum absorption, and probably similar absorption at longer wavelengths, can be attributed to populations of electrically-neutral water clusters that are present in near-Gaussian size distributions in water vapor and moist air. These...

H. R. Carlon

1989-01-01

319

Desalination-of water by vapor-phase transport through hydrophobic nanopores  

E-print Network

We propose a new approach to desalination of water whereby a pressure difference across a vapor-trapping nanopore induces selective transport of water by isothermal evaporation and condensation across the pore. Transport ...

Lee, Jongho

320

The accuracy of water vapor and cloud liquid determination by dual-frequency ground-based microwave radiometry  

Microsoft Academic Search

A dual frequency ground-based radiometer operating in the 1 to 1.4 cm wavelength range can provide continuous measurements of integrated water vapor and cloud liquid water. Using climato- logical data, the accuracy of the vapor and liquid determinations is estimated as a function of cloud amount. Limiting factors in the water determination are uncertainties in water vapor absorption coefficients and,

Ed R. Westwater

1978-01-01

321

Gas Scavenging of Soluble and Insoluble Organic Vapors by Levitated Water Drops.  

NASA Astrophysics Data System (ADS)

Three-millimeter-diameter drops of water were levitated with a standing acoustic wave centered in the jet of a small wind tunnel and the volume changes as the drop evaporates in the presence of 1-propanol vapor were measured. The results are compared with a steady-state continuum evaporation model based on nonideal solution theory. Because the thermodynamic parameter for the 1-propanol-water system are well known, this system provides a test for our model. Good overall agreement between model and experiment results means that small discrepancies can be used to establish limits for dynamic effects. An immiscible liquids version of this model, which accounts for gas scavenging of methyl salicylate, is used to predict the amount of insoluble material scavenged by a drop of water evaporating to dryness. This model predicts that the volume of organic liquid left behind increases as the relative humidity approaches 100%.

Seaver, Mark; Barrett, Amy

1994-07-01

322

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

SciTech Connect

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

Pazmany, Andrew

2006-11-09

323

The Discrepancy Between Measured and Modeled Downwelling Solar Irradiance at the Ground: Dependence on Water Vapor  

NASA Technical Reports Server (NTRS)

Moderate resolution spectra of the downwelling solar irradiance at the ground in north central Oklahoma were measured during the Department of Energy Atmospheric Radiation Measurement Program Intensive Observation Period in the fall of 1997. Spectra obtained under-cloud-free conditions were compared with calculations using a coarse resolution radiative transfer model to examine the dependency of model-measurement bias on water vapor. It was found that the bias was highly correlated with water vapor and increased at a rate of 9 Wm per cm of water. The source of the discrepancy remains undetermined because of the complex dependencies of other variables, most notably aerosol optical depth, on water vapor.

Pilewski, P.; Rabbette, M.; Bergstrom, R.; Marquez, J.; Schmid, B.; Russell, P. B.

2000-01-01

324

Experimental investigation on heat transfer of forced convection condensation of ethanol-water vapor mixtures on a vertical mini-tube  

NASA Astrophysics Data System (ADS)

In this paper, condensation heat transfer characteristics of ethanol-water vapor mixtures on a vertical mini-vertical tube with 1.221 mm outside diameter were investigated experimentally. The experiments were performed at different velocities and pressures over a wide range of ethanol mass fractions in vapor. The test results indicated that, with respect to the change of the vapor-to-surface temperature difference, the condensation curves of the heat transfer coefficients revealed nonlinear characteristics, and had peak values. At 2 % ethanol mass fraction in vapor, the condensation heat transfer coefficient value of the ethanol-water vapor mixture was found to have a maximum heat transfer coefficient of 50 kW m-2 K-1, which was 3-4 times than that of pure steam. The condensation heat transfer coefficients decreased with increased ethanol mass fraction in vapor. The vapor pressure and vapor velocity had a positive effect on the condensation heat transfer coefficients of ethanol-water vapor mixtures.

Chen, Xiping; Chong, Daotong; Wang, Jinshi; Huang, Ronghai; Yan, Junjie

2013-09-01

325

Forced convection heat transfer to air/water vapor mixtures  

NASA Technical Reports Server (NTRS)

Heat transfer coefficients were measured using both dry and humid air in the same forced convection cooling scheme and were compared using appropriate nondimensional parameters (Nusselt, Prandtl and Reynolds numbers). A forced convection scheme with a complex flow field, two dimensional arrays of circular jets with crossflow, was utilized with humidity ratios (mass ratio of water vapor to air) up to 0.23. The dynamic viscosity, thermal conductivity and specific heat of air, steam and air/steam mixtures are examined. Methods for determining gaseous mixture properties from the properties of their pure components are reviewed as well as methods for determining these properties with good confidence. The need for more experimentally determined property data for humid air is discussed. It is concluded that dimensionless forms of forced convection heat transfer data and empirical correlations based on measurements with dry air may be applied to conditions involving humid air with the same confidence as for the dry air case itself, provided that the thermophysical properties of the humid air mixtures are known with the same confidence as their dry air counterparts.

Richards, D. R.; Florschuetz, L. W.

1984-01-01

326

Water vapor adsorption isotherms of agar-based nanocomposite films.  

PubMed

Adsorption isotherms of agar and agar/clay nanocomposite films prepared with different types of nanoclays, that is, a natural montmorillonite (Cloisite Na(+) ) and 2 organically modified montmorillonites (Cloisite 30B and Cloisite 20A), were determined at 3 different temperatures (10, 25, and 40 °C). The water vapor adsorption behavior of the nanocomposite films was found to be greatly influenced with the type of clay. The Guggenheim-Anderson-de Boer (GAB) isotherm model parameters were estimated by using both polynomial regression and nonlinear regression methods and it was found that the GAB model fitted adequately for describing experimental adsorption isotherm data for the film samples. The monolayer moisture content (m(o) ) of the film samples was also greatly affected by the type of nanoclay used, that is, m(o) of nanocomposite films was significantly lower than that of the neat agar film. Nanocomposite films prepared with hydrophobic nanoclays (Cloisite 30B and Cloisite 20A) exhibited lower m(o) values than those prepared with hydrophilic nanoclay (Cloisite Na(+) ). PMID:22417601

Rhim, Jong-Whan

2011-10-01

327

Variations of the glacio-marine air mass front in West Greenland through water vapor isotopes  

NASA Astrophysics Data System (ADS)

While the isotopic distribution of precipitation has been widely used for research in hydrology, paleoclimatology, and ecology for decades, intensive isotopic studies of atmospheric water vapor has only recently been made possible by spectral-based technology. New instrumentation based on this technology opens up many opportunities to investigate short-term atmospheric dynamics involving the water cycle and moisture transport. We deployed a Los Gatos Water Vapor Isotope Analyzer (WVIA) at Kangerlussuaq, Greenland from July 21 to August 15, and measured the water vapor concentration and its isotopic ratios continuously at 10s intervals. A Danish Meteorological Institute site is located about 1 km from the site of the deployment, and meteorological data is collected at 30 min intervals. During the observation period, the vapor concentration of the ambient air ranges from 5608.4 to 11189.4 ppm; dD and d18O range from -254.5 to -177.7 ‰ and -34.2 to -23.2 ‰, respectively. The vapor content (dew point) and the isotopic ratios are both strongly controlled by the wind direction. The easterly winds are associated with dry, isotopically depleted air masses formed over the glacier, while westerly winds are associated with moist and isotopically enriched air masses from the marine/fjord surface. This region typically experiences katabatic winds off of the ice sheet to the east. However, during some afternoons, the wind shifts 180 degrees, blowing off the fjord to the west. This wind switch marks the onset of a sea breeze, and significant isotopic enrichment results. Enrichment in deuterium is up to 60 ‰ with a mean of 15‰, and oxygen-18 is enriched by 3‰ on average and up to 8 ‰. Other afternoons have no change in wind, and only small changes in humidity and vapor isotopic ratios. The humidity and isotopic variations suggest the local atmosphere circulation is dominated by relatively high-pressure systems above the cold glaciers and cool sea surface, and diurnal pressure variations above the relatively warmer land surface in between. During the day as the land is heated, the katabatic wind converges with the sea breeze, producing a front normally over the fjord. On the former type of afternoons, when a sea breeze occurs, the front moves eastward off the fjord, crossing the land and the observation sites in Kangerlussuaq; on the latter afternoons the front remains over the fjord, probably moving east but not far enough to reach the land and Kangerlussuaq, and has no effect on the observation site. The data also show that in addition to this local circulation pattern, the area is influenced by synoptic storm systems as well. A low-pressure system passed slowly across the region over the first 9 days of the observation period. The effects are seen as it interferes with the more regular diurnal cycle of the local circulation described above. In addition to this significant part of the cycle, the effects of lake water evaporation and landscape evapotranspiration is seen in the diurnal cycle. This can be seen on days when the wind direction did not shift in the afternoon, but the dew point and isotopic compositions became slightly higher. This is consistent with moisture contribution from lake evaporation, which is expected to be enriched in both oxygen-18 and deuterium compared to the ambient atmospheric water vapor.

Kopec, B. G.; Lauder, A. M.; Posmentier, E. S.; Feng, X.

2012-12-01

328

Production of long-term global water vapor and liquid water data set using ultra-fast methods to assimilate multi-satellite and radiosonde observations  

NASA Technical Reports Server (NTRS)

During the next decade, many programs and experiments under the Global Energy and Water Cycle Experiment (GEWEX) will utilize present day and future data sets to improve our understanding of the role of moisture in climate, and its interaction with other variables such as clouds and radiation. An important element of GEWEX will be the GEWEX Water Vapor Project (GVaP), which will eventually initiate a routine, real-time assimilation of the highest quality, global water vapor data sets including information gained from future data collection systems, both ground and space based. The comprehensive global water vapor data set being produced by METSAT Inc. uses a combination of ground-based radiosonde data, and infrared and microwave satellite retrievals. This data is needed to provide the desired foundation from which future GEWEX-related research, such as GVaP, can build. The first year of this project was designed to use a combination of the best available atmospheric moisture data including: radiosonde (balloon/acft/rocket), HIRS/MSU (TOVS) retrievals, and SSM/I retrievals, to produce a one-year, global, high resolution data set of integrated column water vapor (precipitable water) with a horizontal resolution of 1 degree, and a temporal resolution of one day. The time period of this pilot product was to be det3ermined by the availability of all the input data sets. January 1988 through December 1988 were selected. In addition, a sample of vertically integrated liquid water content (LWC) was to be produced with the same temporal and spatial parameters. This sample was to be produced over ocean areas only. Three main steps are followed to produce a merged water vapor and liquid water product. Input data from Radiosondes, TOVS, and SSMI/I is quality checked in steps one and two. Processing is done in step two to generate individual total column water vapor and liquid water data sets. The third step, and final processing task, involves merging the individual output products to produce the integrated water vapor product. A final quality control is applied to the merged data sets.

Vonderhaar, T. H.; Reinke, Donald L.; Randel, David L.; Stephens, Graeme L.; Combs, Cynthia L.; Greenwald, Thomas J.; Ringerud, Mark A.; Wittmeyer, Ian L.

1993-01-01

329

Water vapor transport in the lower stratosphere during summer linked to Asian monsoon and horizontal transport  

NASA Astrophysics Data System (ADS)

We compare global water vapor observations from Microwave Limb Sounder (MLS) and simulations with the Lagrangian chemistry transport model CLaMS (Chemical Lagrangian Model of the Stratosphere) to investigate the pathways of water vapor into the lower stratosphere during northern hemisphere (NH) summer. We find good agreement between the simulation and observations, with an effect of the satellite averaging kernel especially at high latitudes. The Asian and American monsoons emerge as regions of particularly high water vapor mixing ratios in the lower stratosphere during boreal summer. In NH mid latitudes and high latitudes, a clear anticorrelation between water vapor and ozone daily tendencies reveals a large region influenced by frequent horizontal transport from low latitudes, extending up to about 450K during summer and fall. Analysis of the zonal mean tracer continuity equation shows that close to the subtropics, this horizontal transport is mainly caused by the residual circulation. In contrast, at higher latitudes, poleward of about 50N, eddy mixing dominates the horizontal water vapor transport. Model simulations with transport barriers confirm that almost the entire annual cycle of water vapor in NH mid latitudes above about 360K, with maximum mixing ratios during summer and fall, is caused by horizontal transport from low latitudes. In the model, highest water vapor mixing ratios in this region are clearly linked to upward transport within the Asian monsoon in the subtropics and subsequent poleward horizontal transport.

Ploeger, Felix; Mueller, Rolf; Riese, Martin; Konopka, Paul

330

Horizontal water vapor transport in the lower stratosphere from subtropics to high latitudes during boreal summer  

NASA Astrophysics Data System (ADS)

We compare global water vapor observations from Microwave Limb Sounder (MLS) and simulations with the Lagrangian chemical transport model CLaMS (Chemical Lagrangian Model of the Stratosphere) to investigate the pathways of water vapor into the lower stratosphere during Northern Hemisphere (NH) summer. We find good agreement between the simulation and observations, with an effect of the satellite averaging kernel especially at high latitudes. The Asian and American monsoons emerge as regions of particularly high water vapor mixing ratios in the lower stratosphere during boreal summer. In NH midlatitudes and high latitudes, a clear anticorrelation between water vapor and ozone daily tendencies reveals a large region influenced by frequent horizontal transport from low latitudes, extending up to about 450K during summer and fall. Analysis of the zonal mean tracer continuity equation shows that close to the subtropics, this horizontal transport is mainly caused by the residual circulation. In contrast, at higher latitudes, poleward of about 50°N, eddy mixing dominates the horizontal water vapor transport. Model simulations with transport barriers confirm that almost the entire annual cycle of water vapor in NH midlatitudes above about 360K, with maximum mixing ratios during summer and fall, is caused by horizontal transport from low latitudes. In the model, highest water vapor mixing ratios in this region are clearly linked to horizontal transport from the subtropics.

Ploeger, F.; Günther, G.; Konopka, P.; Fueglistaler, S.; Müller, R.; Hoppe, C.; Kunz, A.; Spang, R.; Grooß, J.-U.; Riese, M.

2013-07-01

331

Space-Time Variations in Water Vapor as Observed by the UARS Microwave Limb Sounder  

NASA Technical Reports Server (NTRS)

Water vapor in the upper troposphere has a significant impact on the climate system. Difficulties in making accurate global measurements have led to uncertainty in understanding water vapor's coupling to the hydrologic cycle in the lower troposphere and its role in radiative energy balance. The Microwave Limb Sounder (MLS) on the Upper Atmosphere Research Satellite is able to retrieve water vapor concentration in the upper troposphere with good sensitivity and nearly global coverage. An analysis of these preliminary retrievals based on 3 years of observations shows the water vapor distribution to be similar to that measured by other techniques and to model results. The primary MLS water vapor measurements were made in the stratosphere, where this species acts as a conserved tracer under certain conditions. As is the case for the upper troposphere, most of the stratospheric discussion focuses on the time evolution of the zonal mean and zonally varying water vapor. Stratospheric results span a 19-month period and tropospheric results a 36-month period, both beginning in October of 1991. Comparisons with stratospheric model calculations show general agreement, with some differences in the amplitude and phase of long-term variations. At certain times and places, the evolution of water vapor distributions in the lower stratosphere suggests the presence of meridional transport.

Elson, Lee S.; Read, William G.; Waters, Joe W.; Mote, Philip W.; Kinnersley, Jonathan S.; Harwood, Robert S.

1996-01-01

332

Simulation of the effect of water-vapor increase on temperature in the stratosphere  

NASA Astrophysics Data System (ADS)

To analyze the mechanism by which water vapor increase leads to cooling in the stratosphere, the effects of water-vapor increases on temperature in the stratosphere were simulated using the two-dimensional, interactive chemical dynamical radiative model (SOCRATES) of NCAR. The results indicate that increases in stratospheric water vapor lead to stratospheric cooling, with the extent of cooling increasing with height, and that cooling in the middle stratosphere is stronger in Arctic regions. Analysis of the radiation process showed that infrared radiative cooling by water vapor is a pivotal factor in middle-lower stratospheric cooling. However, in the upper stratosphere (above 45 km), infrared radiation is not a factor in cooling; there, cooling is caused by the decreased solar radiative heating rate resulting from ozone decrease due to increased stratospheric water vapor. Dynamical cooling is important in the middle-upper stratosphere, and dynamical feedback to temperature change is more distinct in the Northern Hemisphere middle-high latitudes than in other regions and significantly affects temperature and ozone in winter over Arctic regions. Increasing stratospheric water vapor will strengthen ozone depletion through the chemical process. However, ozone will increase in the middle stratosphere. The change in ozone due to increasing water vapor has an important effect on the stratospheric temperature change.

Bi, Yun; Chen, Yuejuan; Zhou, Renjun; Yi, Mingjian; Deng, Shumei

2011-07-01

333

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

NASA Technical Reports Server (NTRS)

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

Roell, Marilee M.; Fu, Rong

2008-01-01

334

Column atmospheric water vapor and vegetation liquid water retrievals from airborne imaging spectrometer data  

Microsoft Academic Search

High spatial resolution column atmospheric water vapor amounts were derived from spectral data collected by the airborne visible-infrared imaging spectrometer (AVIRIS), which covers the spectral region from 0.4 to 2.5 mum in 10-nm bands and has a ground instantaneous field of view of 20×20 m from an alitude of 20 km. The quantitative derivation is made by curve fitting observed

Bo-Cai Gao; Alexander F. H. Goetz

1990-01-01

335

Trace water vapor determination in nitrogen and corrosive gases using infrared spectroscopy  

SciTech Connect

The generation of particles in gas handling systems as a result of corrosion is a major concern in the microelectronics industry. The corrosion can be caused by the presence of trace quantities of water in corrosive gases such as HCl or HBr. FTIR spectroscopy has been shown to be a method that can be made compatible with corrosive gases and is capable of detecting low ppb levels of water vapor. In this report, the application of FTIR spectroscopy combined with classical least squares multivariate calibration to detect trace H{sub 2}O in N{sub 2}, HCl and HBr is discussed. Chapter 2 discusses the gas handling system and instrumentation required to handle corrosive gases. A method of generating a background spectrum useful to the measurements discussed in this report, as well as in other application areas such as gas phase environmental monitoring, is discussed in Chapter 3. Experimental results obtained with the first system are presented in Chapter 4. Those results made it possible to optimize the design options for the construction of a dedicate system for low ppb water vapor determination. These designs options are discussed in Chapter 5. An FTIR prototype accessory was built. In addition, a commercially available evacuable FTIR system was obtained for evaluation. Test results obtained with both systems are discussed in Chapter 6. Experiments dealing with the interaction between H{sub 2}O-HCl and potential improvements to the detection system are discussed in Chapter 7.

Espinoza, L.H.; Niemczyk, T.M. [Univ. of New Mexico, Albuquerque, NM (United States). Dept. of Chemistry; Stallard, B.R.; Garcia, M.J. [Sandia National Labs., Albuquerque, NM (United States)

1997-06-01

336

Water Vapor Barrier Properties of Zein Films Plasticized with Oleic Acid  

Microsoft Academic Search

Cereal Chem. 75(2):194-199 Water sorption, water vapor permeability, and tensile properties were evaluated for zein films plasticized with oleic acid. The effect of relative humidity on water vapor permeability and tensile properties of films was investigated. Samples were produced by two different methods: casting from a zein solution and stretching from a zein-fatty acid resin. Films were also coated with

Huey-Min Lai; Graciela W. Padua

1998-01-01

337

Impact of modifying the longwave water vapor continuum absorption model on community Earth system model simulations  

NASA Astrophysics Data System (ADS)

The far-infrared (wavelengths longer than 17?m) has been shown to be extremely important for radiative processes in the earth's atmosphere. The strength of the water vapor continuum absorption in this spectral region has largely been predicted using observations at other wavelengths that have been extrapolated using semiempirical approaches such as the Clough-Kneizys-Davies (CKD) family of models. Recent field experiments using new far-infrared instrumentation have supported a factor of 2 decrease in the modeled strength of the foreign continuum at 50?m and a factor of 1.5 increase in the self-continuum at 24?m in the Clough-Kneizys-Davies continuum model (CKD v2.4); these changes are incorporated in the Mlawer-Tobin-CKD continuum model (MT_CKD v2.4). The water vapor continuum in the Community Earth System Model (CESM v1.0) was modified to use the newer model, and the impacts of this change were investigated by comparing output from the original and modified CESM for 20 year integrations with prescribed sea surface temperatures. The change results in an increase in the net upward longwave flux of order 0.5 W m-2between 300 and 400 mb, and a decrease in this flux of about the same magnitude for altitudes below 600 mb. The radiative impact results in a small but statistically significant change in the mean temperature and humidity fields, and also a slight decrease (order 0.5%) of high-cloud amount. The change in the cloud amount modified the longwave cloud radiative forcing, which partially offset the radiative heating caused by the change in the water vapor continuum absorption model.

Turner, D. D.; Merrelli, A.; Vimont, D.; Mlawer, E. J.

2012-02-01

338

Water Vapor Measurements by Howard University Raman Lidar during the WAVES 2006 Campaign  

NASA Technical Reports Server (NTRS)

Retrieval of water vapor mixing ratio using the Howard University Raman Lidar is presented with emphasis on three aspects: i) performance of the lidar against collocated radiosondes and Raman lidar, ii) investigation of the atmospheric state variables when poor agreement between lidar and radiosondes values occurred and iii) a comparison with satellite-based measurements. The measurements were acquired during the Water Vapor Validation Experiment Sondes/Satellites 2006 field campaign. Ensemble averaging of water vapor mixing ratio data from ten night-time comparisons with Vaisala RS92 radiosondes shows on average an agreement within 10 % up to approx. 8 km. A similar analysis of lidar-to-lidar data of over 700 profiles revealed an agreement to within 20 % over the first 7 km (10 % below 4 km). A grid analysis, defined in the temperature - relative humidity space, was developed to characterize the lidar - radiosonde agreement and quantitatively localizes regions of strong and weak correlations as a function of altitude, temperature or relative humidity. Three main regions of weak correlation emerge: i) regions of low relative humidity and low temperature, ii) moderate relative humidity at low temperatures and iii) low relative humidity at moderate temperatures. Comparison of Atmospheric InfraRed Sounder and Tropospheric Emission Sounder satellites retrievals of moisture with that of Howard University Raman Lidar showed a general agreement in the trend but the formers miss a lot of the details in atmospheric structure due to their low resolution. A relative difference of about 20 % is usually found between lidar and satellites measurements.

Adam, M.; Demoz, B. B.; Whiteman, D. N.; Venable, D. D.; Joseph E.; Gambacorta, A.; Wei, J.; Shephard, M. W.; Miloshevich, L. M.; Barnet, C. D.; Herman, R. L.; Fitzgibbon, J.; Connell, R.

2009-01-01

339

Case Studies of Water Vapor and Surface Liquid Water from AVIRIS Data Measured Over Denver, CO and Death Valley, CA  

NASA Technical Reports Server (NTRS)

High spatial resolution column atmospheric water vapor amounts and equivalent liquid water thicknesses of surface targets are retrieved from spectral data collected by the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS). The retrievals are made using a nonlinear least squares curve fitting technique. Two case studies from AVIRIS data acquired over Denver-Platteville area, Colorado and over Death Valley, California are presented. The column water vapor values derived from AVIRIS data over the Denver-Platteville area are compared with those obtained from radiosondes, ground level upward-looking microwave radiometers, and geostationary satellite measurements. The column water vapor image shows spatial variation patterns related to the passage of a weather front system. The column water vapor amounts derived from AVIRIS data over Death Valley decrease with increasing surface elevation. The derived liquid water image clearly shows surface drainage patterns.

Gao, B.-C.; Kierein-Young, K. S.; Goetz, A. F. H.; Westwater, E. R.; Stankov, B. B.; Birkenheuer, D.

1991-01-01

340

A New Criterion to Evaluate Water Vapor Interference in Protein Secondary Structural Analysis by FTIR Spectroscopy  

PubMed Central

Second derivative and Fourier self-deconvolution (FSD) are two commonly used techniques to resolve the overlapped component peaks from the often featureless amide I band in Fourier transform infrared (FTIR) curve-fitting approach for protein secondary structural analysis. Yet, the reliability of these two techniques is greatly affected by the omnipresent water vapor in the atmosphere. Several criteria are currently in use as quality controls to ensure the protein absorption spectrum is negligibly affected by water vapor interference. In this study, through a second derivative study of liquid water, we first argue that the previously established criteria cannot guarantee a reliable evaluation of water vapor interference due to a phenomenon that we refer to as sample’s absorbance-dependent water vapor interference. Then, through a comparative study of protein and liquid water, we show that a protein absorption spectrum can still be significantly affected by water vapor interference even though it satisfies the established criteria. At last, we propose to use the comparison between the second derivative spectra of protein and liquid water as a new criterion to better evaluate water vapor interference for more reliable second derivative and FSD treatments on the protein amide I band. PMID:24901531

Zou, Ye; Ma, Gang

2014-01-01

341

High-accuracy determination of water vapor refractivity by length interferometry.  

PubMed

Humidity is the most problematic parameter for the accurate determination of the refractive index of air. Besides the fact that the humidity measurement can be limiting, the existing empirical equations for the refractive index of moist air are either restricted to 20 degrees C or are based on insufficient knowledge of the refractivity of water vapor. To overcome this problem, a new kind of measurement method for the refractivity of water vapor is suggested that is based on the accurate measurement of the absolute length of a step length by interferometry under vacuum conditions and subsequent measurements at different well-defined absolute water vapor pressures. PMID:16770405

Schödel, René; Walkov, Alexander; Abou-Zeid, Ahmed

2006-07-01

342

Diffusion barriers in the kinetics of water vapor adsorption/desorption on activated carbons  

SciTech Connect

The adsorption of water vapor on a highly microporous coconut-shell-derived carbon and a mesoporous wood-derived carbon was studied. These carbons were chosen as they had markedly different porous structures. The adsorption and desorption characteristics of water vapor on the activated carbons were investigated over the relative pressure range p/p{degree} = 0--0.9 for temperatures in the range 285--313 K in a static water vapor system. The adsorption isotherms were analyzed using the Dubinin-Serpinski equation, and this provided an assessment of the polarity of the carbons. The kinetics of water vapor adsorption and desorption were studied with different amounts of preadsorbed water for set changes in pressure relative to the saturated vapor pressure (p/p{degree}). The adsorption kinetics for each relative pressure step were compared and used to calculate the activation energies for the vapor pressure increments. The kinetic results are discussed in relation to their relative position on the equilibrium isotherm and the adsorption mechanism of water vapor on activated carbons.

Harding, A.W.; Foley, N.J.; Thomas, K.M. [Univ. of Newcastle upon Tyne (United Kingdom)] [Univ. of Newcastle upon Tyne (United Kingdom); Norman, P.R.; Francis, D.C. [CBD, Salisbury (United Kingdom)] [CBD, Salisbury (United Kingdom)

1998-07-07

343

Effects of ambient water vapor pressure and temperature on evaporative water loss in Peromyscus maniculatus and Mus musculus  

Microsoft Academic Search

Summary  The effects of ambient water vapor pressure (VP) and temperature on evaporative water loss (EWL) from the head and trunk ofPeromyscus maniculatus andMus musculus were measured with dew point hygrometry. At a given ambient temperature both head and trunk EWL were directly proportional to the water vapor pressure deficit. Cutaneous EWL in both species was directly related to the difference

Richard M. Edwards; Howard Haines

1978-01-01

344

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

PubMed Central

Combined measurements of water isotopologues of a snow pit at Vostok over the past 60 y reveal a unique signature that cannot be explained only by climatic features as usually done. Comparisons of the data using a general circulation model and a simpler isotopic distillation model reveal a stratospheric signature in the 17O-excess record at Vostok. Our data and theoretical considerations indicate that mass-independent fractionation imprints the isotopic signature of stratospheric water vapor, which may allow for a distinction between stratospheric and tropospheric influences at remote East Antarctic sites. PMID:23798406

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

2013-01-01

345

Analysis of precipitable water vapor and liquid water path by microwave radiometer during 2001 - 2002  

NASA Astrophysics Data System (ADS)

Based on the observation of the Microwave Radiometer (MWR, WVR-1100) at Cheongju and Hapcheon in South Korea, the precipitable water vapor (PWV) and liquid water path (LWP) have been analyzed. Comparison of the PWVs measured by MWR at Cheongju and Hapcheon gives good agreement above the 0.9 of correlation coefficient with that of radiosonde at the two nearest sites (Osan and Gwangju), respectively. The PWVs show the seasonality, but do not the regional characteristics evidently. The LWP shows not only the seasonality but also regional difference. These regional characteristics seem come from the regional different solar radiation.

Yang, H.; Chang, K.; Lee, S.; Jang, Y.; Choi, Y.

2007-12-01

346

Fatigue Resistance of Asphalt Mixtures Affected by Water Vapor Movement  

E-print Network

the fatigue crack growth of pavement would result from such moisture accumulation. To fulfill these two objectives, a diffusion model was first established to illustrate the wetting process of the surface asphalt layer due to the vapor migration from subgrade...

Tong, Yunwei

2013-11-08

347

DIURNAL CYCLE OF PRECIPITABLE WATER VAPOR OVER SPAIN  

SciTech Connect

Despite the importance of the diurnal cycle of precipitable water vapor (PWV), its knowledge is very limited due to the lack of data with sufficient temporal resolution. Currently, from GPS receivers, PWV can be obtained with high temporal resolution in all weather conditions for all hours of the day. In this study we have calculated the diurnal cycle of PWV for ten GPS stations over Spain. The minimum value is reached approximately at the same time at all the stations, ~0400-0500 UTC, whereas the maximum is reached in the second half of the day, but with a larger dispersion of its occurrence between stations. The amplitude of the cycle ranges between 0.72 mm and 1.78 mm. The highest values are recorded at the stations on the Mediterranean coast, with a doubling of the values of the stations on the Atlantic coast or inland. The amplitude of the PWV cycle, relative to the annual mean value, ranges between 8.8 % on the Mediterranean coast and 3.6 % on the Atlantic coast. Two distinctly different seasonal diurnal cycles have been identified, one in winter and other in summer, with spring and autumn being only transition states. The winter cycle is quite similar at all locations, whereas in summer, local effects are felt strongly, making the diurnal cycle quite different between stations. The amplitude of the summer cycle is 1.69 mm, it is almost double the winter one (0.93 mm). Analogous to the annual cycles, the seasonal cycles of the different stations are more similar during the night and early morning hours than during the afternoon. The observed features of the PWV diurnal cycle are explained in a qualitative way on the basis of the air temperature, the transport of moisture by local winds, and the turbulent vertical mixing.

Ortiz de Galisteo, J. P.; Cachorro, V. E.; Toledano, C.; Torres, B.; Laulainen, Nels S.; Bennouna, Yasmine; de Frutos, A. M.

2011-05-20

348

Single-beam water vapor detection system with automatic photoelectric conversion gain control  

NASA Astrophysics Data System (ADS)

A single-beam optical sensor system with automatic photoelectric conversion gain control is proposed for doing high reliability water vapor detection under relatively rough environmental conditions. Comparing to a dual-beam system, it can distinguish the finer photocurrent variations caused by the optical power drift and provide timely compensation by automatically adjusting the photoelectric conversion gain. This system can be rarely affected by the optical power drift caused by fluctuating ambient temperature or variation of fiber bending loss. The deviation of the single-beam system is below 1.11% when photocurrent decays due to fiber bending loss for bending radius of 5 mm, which is obviously lower than the dual-beam system (8.82%). We also demonstrate the long-term stability of the single-beam system by monitoring a 660 ppm by volume (ppmv) water vapor sample continuously for 24 h. The maximum deviation of the measured concentration during the whole testing period does not exceed 10 ppmv. Experiments have shown that the new system features better reliability and is more apt for remote sensing application which is often subject to light transmission loss.

Zhu, C. G.; Chang, J.; Wang, P. P.; Wang, Q.; Wei, W.; Liu, Z.; Zhang, S. S.

2014-11-01

349

Evaluation of AERONET precipitable water vapor versus microwave radiometry, GPS, and radiosondes at ARM sites  

NASA Astrophysics Data System (ADS)

this paper we present comparisons of Aerosol Robotic Network (AERONET) precipitable water vapor (W) retrievals from Sun photometers versus radiosonde observations and other ground-based retrieval techniques such as microwave radiometry (MWR) and GPS. The comparisons make use of the extensive measurements made within the U.S. Department of Energy Atmospheric Radiation Measurement Program (ARM), mainly at their permanent sites located at the Southern Great Plains (Oklahoma, U.S.), Nauru Islands, and Barrow (Alaska, U.S.). These places experience different types of weather which allows the comparison of W under different conditions. Radiosonde and microwave radiometry data were provided by the ARM program while the GPS data were obtained from the SOUMINET network. In general, W obtained by AERONET is lower than those obtained by MWR and GPS by ~6.0-9.0% and ~6.0-8.0%, respectively. The AERONET values are also lower by approximately 5% than those obtained from the numerous balloon-borne radiosondes launched at the Southern Great Plains. These results point toward a consistent dry bias in the retrievals of W by AERONET of approximately 5-6% and a total estimated uncertainty of 12-15%. Differences with respect to MWR retrievals are a function of solar zenith angle pointing toward a possible bias in the MWR retrievals. Finally, the ability of AERONET precipitable water vapor retrievals to provide long-term records of W in diverse climate regimes is demonstrated.

Pérez-Ramírez, Daniel; Whiteman, David N.; Smirnov, Alexander; Lyamani, Hassan; Holben, Brent N.; Pinker, Rachel; Andrade, Marcos; Alados-Arboledas, Lucas

2014-08-01

350

Temperature sensitivity of differential absorption lidar measurements of water vapor in the 720-nm region  

NASA Technical Reports Server (NTRS)

Recently measured properties of water vapor (H2O) absorption lines have been used in calculations to evalute the temperature sensitivity of differential absorption lidar (Dial) H2O measurements. This paper estimates the temperature sensitivity of H2O lines in the 717-733-nm region for both H2O mixing ratio and number density measurements, and discusses the influence of the H2O line ground state energies E-double-prime, the H2O absorption linewidths, the linewidth temperature dependence parameter, and the atmospheric temperature and pressure variations with altitude and location on the temperature sensitivity calculations. Line parameters and temperature sensitivity calculations for 67 H2O lines in the 720-nm band are given which can be directly used in field experiments. Water vapor lines with E-double-prime values in the 100-300/cm range were found to be optimum for Dial measurements of H2O number densities, while E-double-prime values in the 250-500/cm range were found to be optimum for H2O mixing ratio measurements.

Browell, Edward V.; Ismail, Syed; Grossmann, Benoist E.

1991-01-01

351

In-Flight Performance of the Water Vapor Monitor Onboard the Sofia Observatory  

NASA Technical Reports Server (NTRS)

NASA's Stratospheric Observatory for Infrared Astronomy (SOFIA) airborne observatory flies in a modified B747-SP aircraft in the lower stratosphere above more than 99.9% of the Earth's water vapor. As low as this residual water vapor is, it will still affect SOFIA's infrared and sub-millimeter astronomical observations. As a result, a heterodyne instrument has been developed to observe the strength and shape of the 1830Hz rotational line of water, allowing measurements of the integrated water vapor overburden in flight. In order to be useful in correcting the astronomical signals, the required measured precipitable water vapor accuracy must be 2 microns or better, 3 sigma, and measured at least once a minute. The Water Vapor Monitor has flown 22 times during the SOFIA Early Science shared-risk period. The instrument water vapor overburden data obtained were then compared with concurrent data from GOES-V satellites to perform a preliminary calibration of the measurements. This presentation will cover the.results of these flights. The final flight calibration necessary to reach the required accuracy will await subsequent flights following the SOFIA observatory upgrade that is taking place during the spring and summer of 2012.

Roellig, Thomas L.; Yuen, Lunming; Sisson, David; Hang, Richard

2012-01-01

352

Observed Increase of TTL Temperature and Water Vapor in Polluted Couds over Asia  

SciTech Connect

Aerosols can affect cloud particle size and lifetime, which impacts precipitation, radiation and climate. Previous studies1-4 suggested that reduced ice cloud particle size and fall speed due to the influence of aerosols may increase evaporation of ice crystals and/or cloud radiative heating in the tropical tropopause layer (TTL), leading to higher water vapor abundance in air entering the stratosphere. Observational substantiation of such processes is still lacking. Here, we analyze new observations from multiple NASA satellites to show the imprint of pollution influence on stratospheric water vapor. We focus our analysis on the highly-polluted South and East Asia region during boreal summer. We find that "polluted" ice clouds have smaller ice effective radius than "clean" clouds. In the TTL, the polluted clouds are associated with warmer temperature and higher specific humidity than the clean clouds. The water vapor difference between the polluted and clean clouds cannot be explained by other meteorological factors, such as updraft and detrainment strength. Therefore, the observed higher water vapor entry value into the stratosphere in the polluted clouds than in the clean clouds is likely a manifestation of aerosol pollution influence on stratospheric water vapor. Given the radiative and chemical importance of stratospheric water vapor, the increasing emission of aerosols over Asia may have profound impacts on stratospheric chemistry and global energy balance and water cycle.

Su, Hui; Jiang, Jonathan; Liu, Xiaohong; Penner, J.; Read, William G.; Massie, Steven T.; Schoeberl, Mark R.; Colarco, Peter; Livesey, Nathaniel J.; Santee, Michelle L.

2011-06-01

353

Recipes for writing algorithms to retrieve columnar water vapor for three-band multispectral data  

NASA Astrophysics Data System (ADS)

Many papers have considered the theory of retrieving columnar water vapor using the continuum interpolated band ratio (CIBR) and a few the atmospherically pre-corrected differential absorption (APDA) methods. In this paper we aim at giving recipes to actually implement CIBR and APDA for the Multi-spectral Thermal Imager (MTI) with the hope that they can be easily adapted to other sensors such as MODIS, AVIRIS and HYDICE. The algorithms have the four following steps in common: (1) running a radiative transfer (RT) algorithm for a range of water vapor values and a particular observation geometry, (2) computation of sensor band-averaged radiances, (3) computation of a non-linear fit of channel ratios (CIBR or APDA) as a function of water vapor, (4) application of the inverse fit to retrieve columnar water vapor as a function of channel ratio.

Borel, Christoph C.; Hirsch, Karen L.; Balick, Lee K.

2001-08-01

354

RECIPES FOR WRITING ALGORITHMS TO RETRIEVE COLUMNAR WATER VAPOR FOR 3-BAND MULTI-SPECTRAL DATA.  

SciTech Connect

Many papers have considered the theory of retrieving columnar water vapor using the continuum interpolated band ratio (CIBR) and a few the atmospherically pre-corrected differential absorption (APDA) methods. In this paper we aim at giving recipes to actually implement CIBR and APDA for the Multi-spectral Thermal Imager (MTI) with the hope that they can be easily adapted to other sensors such as MODIS, AVIRIS and HYDICE. The algorithms have the four following steps in common: (1) running a radiative transfer (RT) algorithm for a range of water vapor values and a particular observation geometry, (2) computation of sensor band-averaged radiances, (3) computation of a non-linear fit of channel ratios (CIBR or APDA) as a function of water vapor, (4) application of the inverse fit to retrieve columnar water vapor as a function of channel ratio.

Borel, C. C. (Christoph C.); Hirsch, K. L. (Karen L.); Balick, L. K. (Lee K.)

2001-01-01

355

Physical-statistical retrieval of water vapor profiles using SSM/T-2 Sounder data  

NASA Astrophysics Data System (ADS)

The feasibility of retrieving water vapor profiles from downlooking passive microwave sounder data is demonstrated by usage of a retrieval algorithm which extends Bayesian optimal estimation. Special Sensor Microwave T-2 (SSM/T-2) downlooking sounder data, consisting of brightness temperature measurements sensitive to water vapor, are used together with total water vapor content data for computing tropospheric water vapor profiles. The significant nonlinearity in the cost function, an implication of the corresponding (nonlinear) radiative transfer equation, necessitates several extensions of the well-known optimal estimation inversion scheme. We supplemented the scheme by simulated annealing and iterative a priori lightweighting and obtained a powerful physical-statistical hybrid algorithm. Retrievals based on SSM/T-2 data were compared to atmospheric analyses of the European Centre for Medium-Range Weather Forecasts (ECMWF). A statistical validation of the retrieved profiles is presented. The comparisons indicate an approximate accuracy of about 15 to 20 percent for relative humidity.

Rieder, Markus J.; Kirchengast, Gottfried

356

Performance modeling of ultraviolet Raman lidar systems for daytime profiling of atmospheric water vapor  

NASA Technical Reports Server (NTRS)

We describe preliminary results from a comprehensive computer model developed to guide optimization of a Raman lidar system for measuring daytime profiles of atmospheric water vapor, emphasizing an ultraviolet, solar-blind approach.

Ferrare, R. A.; Whiteman, D. N.; Melfi, S. H.; Goldsmith, J. E. M.; Bisson, S. E.; Lapp, M.

1991-01-01

357

Comparison of columnar water-vapor measurements from solar transmittance methods.  

PubMed

In the fall of 1997 the Atmospheric Radiation Measurement program conducted a study of water-vapor-abundance-measurement at its southern Great Plains site. The large number of instruments included four solar radiometers to measure the columnar water vapor (CWV) by measuring solar transmittance in the 0.94-mum water-vapor absorption band. At first, no attempt was made to standardize our procedures to the same radiative transfer model and its underlying water-vapor spectroscopy. In the second round of comparison we used the same line-by-line code (which includes recently corrected H(2)O spectroscopy) to retrieve CWV from all four solar radiometers, thus decreasing the mean CWV by 8-13%. The remaining spread of 8% is an indication of the other-than-model uncertainties involved in the retrieval. PMID:18357188

Schmid, B; Michalsky, J J; Slater, D W; Barnard, J C; Halthore, R N; Liljegren, J C; Holben, B N; Eck, T F; Livingston, J M; Russell, P B; Ingold, T; Slutsker, I

2001-04-20

358

The Oxidation Rate of SiC in High Pressure Water Vapor Environments  

NASA Technical Reports Server (NTRS)

CVD SiC and sintered alpha-SiC samples were exposed at 1316 C in a high pressure burner rig at total pressures of 5.7, 15, and 25 atm for times up to 100h. Variations in sample emittance for the first nine hours of exposure were used to determine the thickness of the silica scale as a function of time. After accounting for volatility of silica in water vapor, the parabolic rate constants for Sic in water vapor pressures of 0.7, 1.8 and 3.1 atm were determined. The dependence of the parabolic rate constant on the water vapor pressure yielded a power law exponent of one. Silica growth on Sic is therefore limited by transport of molecular water vapor through the silica scale.

Opila, Elizabeth J.; Robinson, R. Craig

1999-01-01

359

Microcalorimetric Measurement of the Interactions Between Water Vapor and Amorphous Pharmaceutical Solids  

Microsoft Academic Search

Purpose. Use a microcalorimetric technique to measure the interactions between water vapor and amorphous pharmaceutical solids and describe the relationship between long-term physical stability and the storage relative humidity (RH) at constant temperature.

David Lechuga-Ballesteros; Aziz Bakri; Danforth P. Miller

2003-01-01

360

Optoacoustic measurements of water vapor absorption at selected CO laser wavelengths in the 5-micron region  

NASA Technical Reports Server (NTRS)

Measurements of water vapor absorption were taken with a resonant optoacoustical detector (cylindrical pyrex detector, two BaF2 windows fitted into end plates at slight tilt to suppress Fabry-Perot resonances), for lack of confidence in existing spectral tabular data for the 5-7 micron region, as line shapes in the wing regions of water vapor lines are difficult to characterize. The measurements are required for air pollution studies using a CO laser, to find the differential absorption at the wavelengths in question due to atmospheric constituents other than water vapor. The design and performance of the optoacoustical detector are presented. Effects of absorption by ambient NO are considered, and the fixed-frequency discretely tunable CO laser is found suitable for monitoring urban NO concentrations in a fairly dry climate, using the water vapor absorption data obtained in the study.

Menzies, R. T.; Shumate, M. S.

1976-01-01

361

NSIPP North America Forecast Dec. 1, 2001 - Nov. 30, 2002: Sea Surface Temperature Anomaly, Water Vapor  

NSDL National Science Digital Library

Sea surface temperature anomalies and atmospheric water vapor forecasted in the northern Pacific and over North America for December 2001 through November 2002, from the NASA Seasonal-to-Interannual Prediction Project

Waldrop, John; Mitchell, Horace; Adamec, David

2002-02-06

362

Reaction kinetics for the high temperature oxidation of Pu--1wt%Ga in water vapor  

SciTech Connect

Oxidation of plutonium metal is greatly accelerated by the presence of water vapor. The magnitude of the effect of water vapor on oxidation kinetics is determined by temperature, water concentration, and oxygen concentration. Most of the previous work has been directed toward evaluating the effect of moisture on the atmospheric oxidation of plutonium. Work on the isolation and characterization of the water reaction with plutonium has been very limited. The present work was undertaken to determine the kinetics of the plutonium--water reaction over a wide range of temperature and pressure. Reaction kinetics were measured using a vacuum microbalance system. The temperature range investigated was 100--500/degree/C. The effect of water vapor pressure on reaction kinetics was determined at 300/degree/C by varying the water pressure from 0.1 to 15 Torr. 2 figs.

Stakebake, J L; Saba, M A

1988-01-01

363

Water vapor adsorption onto activated carbons prepared from cattle manure compost (CMC)  

NASA Astrophysics Data System (ADS)

Activated carbons were prepared from cattle manure compost (CMC) using zinc chloride activation. The structural and surface chemical characteristics of CMC-based activated carbons were determined by N 2 adsorption-desorption and Boehm titration, respectively. The water vapor adsorption properties of the prepared activated carbons with various pore structure and surface nature were examined, and the mechanism of water adsorbed onto activated carbon was also discussed. The results show that the adsorption of water vapor on carbons begins at specific active sites at low relative humidity (RH), followed by micropore filling at medium RH through the formation of pentamer cluster of water molecules in the narrow micropores. The water vapor adsorption capacity of activated carbon is predominantly dependent on its pore volume and surface area. Although capillary condensation is not the mechanism for water adsorption onto activated carbon, water can adsorb on narrow mesopore to some extent.

Qian, Qingrong; Sunohara, Satoshi; Kato, Yuichi; Zaini, Muhammad Abbas Ahmad; Machida, Motoi; Tatsumoto, Hideki

2008-05-01

364

Spatial and Temporal Structure of Atmospheric Water Vapor Transport in the Mackenzie River Basin  

Microsoft Academic Search

The transport of water vapor through the Mackenzie River basin, a typical high-latitude river basin, is examined for the period from August to October 1994. The spatial and temporal variability in the transport is considered with both objectively analyzed fields and radiosonde data.Previous studies of the high-latitude water vapor have made use of radiosonde data and have been able to

Vladimir V. Smirnov; G. W. K. Moore

1999-01-01

365

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

NASA Technical Reports Server (NTRS)

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

Meneghini, Robert; Liao, Liang; Tian, Lin

2006-01-01

366

The role of diffusion processes during water-vapor releases in the ionospheric F-region  

Microsoft Academic Search

It has been previously observed that releases of water vapor in the F-region lead to a reduction in electron denisty, i.e., to the so-called ionospheric-hole effect. In the present work, a solution of the set of continuity equations is used to compare theoretical models for the water-vapor release, both with and without allowance for the diffusion of charged particles. It

M. N. Vlasov; S. A. Pokhunkov

1989-01-01

367

Rapid formation of Jupiter by diffuse redistribution of water vapor in the solar nebula  

Microsoft Academic Search

In the present, water-vapor diffusive redistribution and condensation model of solid material abundance enhancement in the solar nebula's Jupiter-formation region, the assumed turbulent nebula temperatures decrease inversely with radial distance from the center, and time-scales are set by turbulent viscosities. The length scale for condensation of diffusively-transported water vapor is about 0.4 AU, and the surface density of ice in

David J. Stevenson; Jonathan I. Lunine

1988-01-01

368

Forced Dispersion of Liquefied Natural Gas Vapor Clouds with Water Spray Curtain Application  

E-print Network

FORCED DISPERSION OF LIQUEFIED NATURAL GAS VAPOR CLOUDS WITH WATER SPRAY CURTAIN APPLICATION A Dissertation by MORSHED ALI RANA Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment... of the requirements for the degree of DOCTOR OF PHILOSOPHY December 2009 Major Subject: Chemical Engineering FORCED DISPERSION OF LIQUEFIED NATURAL GAS VAPOR CLOUDS WITH WATER SPRAY CURTAIN APPLICATION A Dissertation by MORSHED ALI RANA...

Rana, Morshed A.

2011-02-22

369

Evaluation of volcanic aerosol impacts on atmospheric water vapor using CMIP3 and CMIP5 simulations  

NASA Astrophysics Data System (ADS)

The uncertainty in estimates of volcanic forcing and in the way general circulation models (GCMs) implement volcanic forcing affects the accuracy of the simulated atmospheric water vapor response to volcanic eruptions, which in turn influences the design of hydrologic infrastructure. This paper aims to investigate whether and to what extent the models can simulate the volcanic impacts on atmospheric water vapor. While a Kolmogorov-Smirnov (K-S) test on atmospheric water vapor from GCMs, reanalysis products, and observations all imply that volcanic aerosols have a statistically significant impact on atmospheric water vapor, and the areal extent of global atmospheric water vapor affected by volcanic eruptions is oversimulated by GCMs. Additionally, the spatial and temporal patterns of the volcano-related water vapor variability are not well simulated by GCMs. Furthermore, the strong negative correlation between aerosol optical depth and water vapor residual is observed only in the equatorial Atlantic and Indian Oceans, and parts of the western Pacific Ocean rather than across the entire globe as simulated by volcanic forcing included Coupled Model Intercomparison Project Phase 3 (CMIP3) multimodel average (or over nearly the entire tropics by volcanic forcing included the BCC-CSM1.1). Although the uncompleted removal of El Niño-Southern Oscillation signal may compromise the results, it is still safe, after performing the control run of K-S test, to draw the conclusion that while volcanic forcing does exert a significant impact on atmospheric water vapor, the underlying relationship is considerably more complex than that evident in GCM simulations.

Li, Jingwan; Sharma, Ashish

2013-05-01

370

Upper-Tropospheric Winds Derived from Geostationary Satellite Water Vapor Observations  

NASA Technical Reports Server (NTRS)

The coverage and quality of remotely sensed upper-tropospheric moisture parameters have improved considerably with the deployment of a new generation of operational geostationary meteorological satellites: GOES-8/9 and GMS-5. The GOES-8/9 water vapor imaging capabilities have increased as a result of improved radiometric sensitivity and higher spatial resolution. The addition of a water vapor sensing channel on the latest GMS permits nearly global viewing of upper-tropospheric water vapor (when joined with GOES and Meteosat) and enhances the commonality of geostationary meteorological satellite observing capabilities. Upper-tropospheric motions derived from sequential water vapor imagery provided by these satellites can be objectively extracted by automated techniques. Wind fields can be deduced in both cloudy and cloud-free environments. In addition to the spatially coherent nature of these vector fields, the GOES-8/9 multispectral water vapor sensing capabilities allow for determination of wind fields over multiple tropospheric layers in cloud-free environments. This article provides an update on the latest efforts to extract water vapor motion displacements over meteorological scales ranging from subsynoptic to global. The potential applications of these data to impact operations, numerical assimilation and prediction, and research studies are discussed.

Velden, Christopher S.; Hayden, Christopher M.; Nieman, Steven J.; Menzel, W. Paul; Wanzong, Steven; Goerss, James S.

1997-01-01

371

Water Vapor, Differential Rates of Warming, Available Potential Energy, and the Hadley Circulation  

NASA Astrophysics Data System (ADS)

In 1686 Halley advanced the idea that trade winds and monsoon circulations were tied to differential patterns in solar heating. Hadley (1735) soon added the important concept of conservation of angular momentum. Lorenz (1955) described how temperature gradients produced the potential energy, maintaining the general circulation. The differential heating patterns that drive the Hadley circulation arise through variations in insolation and water vapor-related warming. Water vapor is a very effective greenhouse gas, and the tropical-to-extra tropical water vapor gradient increases the longwave radiation absorbed at the surface, increasing the meridional temperature gradient. Increases in water vapor are accepted as one robust feature of anthropogenic climate change. While it is generally accepted that that the 'rich will get richer' (in the sense that moist regions will see a disproportionate increase in water vapor), there has been relatively little discussion of how these differential changes in moisture will translate into differential changes in water vapor related increases in longwave radiation. These increases in longwave radiation may result in a tendency for the 'warm to get warmer' and the Hadley circulation to intensify. In this presentation we examine this issue using i) a single column plane-parallel radiative transfer model, ii) reanalysis climate fields, iii) sea surface temperature observations, and iv) historical climate change simulations drawn from the phase 5 coupled model intercomparison project (CMIP5) archive. We conclude with an examination of potential impacts on arid and semi-arid zones.

Funk, C. C.; Dettinger, M. D.

2012-12-01

372

Interaction of water vapor with clean and oxygen-covered uranium surfaces  

NASA Astrophysics Data System (ADS)

The interaction of water vapor with clean and oxygen-covered high-purity polycrystalline uranium surfaces was studied between 85 and 298 K with thermal desorption spectroscopy (TDS), X-ray photoelectron spectroscopy (XPS), and secondary ion mass spectroscopy (SIMS). Saturation of the uranium surface with oxygen or water vapor produced an asymmetric O1s photoelectron peak that consisted of a main oxide contribution and a small component assigned to strongly chemisorbed oxygen or hydroxyl ions, respectively. Saturation of the clean or oxygen-covered surface with water vapor at 85 K produced multilayer ice that was converted to oxide and adsorbed hydroxyl ions after warming to room temperature. A significant difference in binding energies was observed in the O1s spectra between water vapor adsorption on clean and oxygen-covered surfaces that lends support to the oxygen inhibition of the water vapor-uranium reaction by a surface mechanism. The initial oxidation mechanisms of uranium with oxygen and water vapor are discussed.

Winer, K.; Colmenares, C. A.; Smith, R. L.; Wooten, F.

1987-04-01

373

Initial Evaluation of Profiles of Temperature, Water Vapor, and Cloud Liquid Water from a New Microwave Profiling Radiometer.  

National Technical Information Service (NTIS)

To measure the vertical profiles of temperature and water vapor that are essential for modeling atmospheric processes, the Atmospheric Radiation Measurement (ARM) Program of the U. S. Department of Energy launches approximately 2600 radiosondes each year ...

J. C. Liljegren, B. M. Lesht, S. Kato, E. E. Clothiaux

2001-01-01

374

Correction technique for Raman water vapor lidar signal-dependent bias and suitability for water vapor trend monitoring in the upper troposphere  

NASA Astrophysics Data System (ADS)

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

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

2012-11-01

375

WATER VAPOR IN NEARBY INFRARED GALAXIES AS PROBED BY HERSCHEL  

SciTech Connect

We report the first systematic study of the submillimeter water vapor rotational emission lines in infrared (IR) galaxies based on the Fourier Transform Spectrometer (FTS) data of Herschel SPIRE. Among the 176 galaxies with publicly available FTS data, 45 have at least one H{sub 2}O emission line detected. The H{sub 2}O line luminosities range from {approx}1 Multiplication-Sign 10{sup 5} L{sub Sun} to {approx}5 Multiplication-Sign 10{sup 7} L{sub Sun} while the total IR luminosities (L{sub IR}) have a similar spread ({approx}1-300 Multiplication-Sign 10{sup 10} L{sub Sun }). In addition, emission lines of H{sub 2}O{sup +} and H{sub 2}{sup 18}O are also detected. H{sub 2}O is found, for most galaxies, to be the strongest molecular emitter after CO in FTS spectra. The luminosity of the five most important H{sub 2}O lines is near-linearly correlated with L{sub IR}, regardless of whether or not strong active galactic nucleus signature is present. However, the luminosity of H{sub 2}O(2{sub 11}-2{sub 02}) and H{sub 2}O(2{sub 20}-2{sub 11}) appears to increase slightly faster than linear with L{sub IR}. Although the slope turns out to be slightly steeper when z {approx} 2-4 ULIRGs are included, the correlation is still closely linear. We find that L{sub H{sub 2O}}/L{sub IR} decreases with increasing f{sub 25}/f{sub 60}, but see no dependence on f{sub 60}/f{sub 100}, possibly indicating that very warm dust contributes little to the excitation of the submillimeter H{sub 2}O lines. The average spectral line energy distribution (SLED) of the entire sample is consistent with individual SLEDs and the IR pumping plus collisional excitation model, showing that the strongest lines are H{sub 2}O(2{sub 02}-1{sub 11}) and H{sub 2}O(3{sub 21}-3{sub 12}).

Yang Chentao [Department of Astronomy, Beijing Normal University, Beijing 100875 (China); Gao Yu; Liu Daizhong [Purple Mountain Observatory/Key Lab of Radio Astronomy, Chinese Academy of Sciences, Nanjing 210008 (China); Omont, A. [Institut d'Astrophysique de Paris, UPMC Universite Paris 06, UMR7095, F-75014 Paris (France); Isaak, K. G. [ESA Astrophysics Missions Division, ESTEC, P.O. Box 299, 2200 AG Noordwijk (Netherlands); Downes, D. [Institut de Radioastronomie Millimetrique (IRAM), 300 rue de la Piscine, F-38406 Saint-Martin d'Heres (France); Van der Werf, P. P. [Leiden Observatory, Leiden University, Post Office Box 9513, NL-2300 RA Leiden (Netherlands); Lu Nanyao [Infrared Processing and Analysis Center, California Institute of Technology, MS 100-22, Pasadena, CA 91125 (United States)

2013-07-10

376

Oxidation of Ultra-High Temperature Ceramics in Water Vapor  

NASA Technical Reports Server (NTRS)

Ultra high temperature ceramics (UHTCs) including HfB2 + SiC (20% by volume), ZrB2 + SiC (20% by volume) and ZrB2 + SiC (14% by volume) + C (30% by volume) have historically been evaluated as reusable thermal protection systems for hypersonic vehicles. This study investigates UHTCs for use as potential combustion and aeropropulsion engine materials. These materials were oxidized in water vapor (90%) using a cyclic vertical furnace at 1 atm. The total exposure time was 10 hours at temperatures of 1200, 1300, and 1400 C. CVD SiC was also evaluated as a baseline comparison. Weight change measurements, X-ray diffraction analyses, surface and cross-sectional SEM and EDS were performed. These results will be compared with tests ran in static air at temperatures of 1327, 1627, and 1927 C. Oxidation comparisons will also be made to the study by Tripp. A small number of high pressure burner rig (HPBR) results at 1100 and 1300 C will also be discussed. Specific weight changes at all three temperatures along with the SIC results are shown. SiC weight change is negligible at such short duration times. HB2 + SiC (HS) performed the best out of all the tested UHTCS for all exposure temperatures. ZrB2 + Sic (ZS) results indicate a slightly lower oxidation rate than that of ZrBl + SiC + C (ZCS) at 1200 and 1400 C, but a clear distinction can not be made based on the limited number of tested samples. Scanning electron micrographs of the cross-sections of all the UHTCs were evaluated. A representative area for HS is presented at 1400 C for 26 hours which was the composition with the least amount of oxidation. A continuous SiO2 scale is present in the outer most edge of the surface. An image of ZCS is presented at 1400 C for 10 hours, which shows the most degradation of all the compositions studied. Here, the oxide surface is a mixture of ZrSiO4, ZrO2 and SO2.

Nguyen, QuynhGiao N.; Opila, Elizabeth J.; Robinson, Raymond C.

2003-01-01

377

WARM WATER VAPOR AROUND SAGITTARIUS B21 Jose Cernicharo, Javier R. Goicoechea,2  

E-print Network

transfer Online material: color figures 1. INTRODUCTION The determination of water abundance in space been used to map the extended emission of water vapor in Orion: the 313 220 (hereafter the 183 GHz line Infrared Space Observatory (ISO) and Submillimeter Wave Astronomy Satellite (SWAS ) observations that water

Pardo-Carrión, Juan R.

378

Skin Irritancy of Surfactants As Assessed by Water Vapor Loss Measurements  

Microsoft Academic Search

A method to assess the irritancy of chemicals on human skin that is based on measurements of skin (water) vapor loss (SVL) is presented. The SVL measurements were performed with the Servo Med Evaporimeter in a group of 27 healthy volunteers. Four surfactants, distilled water, and NaCl 0.9% in distilled water were assayed. For the exposures a chamber technique was

Pieter G. M. Van Der Valk; Johan P. Nater; Eric Bleumink

1984-01-01

379

Water vapor in the Martian atmosphere - A discussion of the Viking data  

NASA Technical Reports Server (NTRS)

A summary of calculations describing the Martian atmosphere water vapor content based on data from the Mars Atmospheric Water Detectors carried by the Viking landers is presented. The water column has been observed to vary with season, time of day, and locality. Over 5 yr of continuous data collection has permitted modeling of the Martian year into 24 seasonal periods of planetocentric solar longitude, with gaps in the model due to the presence of dust storms. The vapor content is asymmetric pole-to-pole, but symmetric latitudinally with respect to the equator. Low elevation areas display a higher vapor content, especially with rapid height changes in nearby terrain. Dust storms reduced the total atmospheric vapor, with concentration shifts tending toward the north, from where it is expected renewed balances will be reinstated. Consideration is also given to diurnal variations, and variations due to temperature, composition, and wind velocity.

Doms, P. E.

1982-01-01

380

Waste storage in the vadose zone affected by water vapor condensation and leaching  

SciTech Connect

One of the major concerns associated with waste storage in the vadose zone is that toxic materials may somehow be leached and transported by advecting water down to the water table and reach the accessible environment through either a well or discharge to a river. Consequently, care is taken to provide barriers over and around the storage sites to reduce contact between infiltrating water and the buried waste form. In some cases, it is important to consider the intrusion of water vapor as well as water in the liquid phase. Water vapor diffuses through porous material along vapor pressure gradients. A slightly low temperature, or the presence of water-soluble components in the waste, favors water condensation resulting in leaching of the waste form and advection of water-soluble components to the water table. A simple analysis is presented that allows one to estimate the rate of vapor condensation as a function of waste composition and backfill materials. An example using a waste form surrounded by concrete and gravel layers is presented. The use of thermal gradients to offset condensation effects of water-soluble components in the waste form is discussed. Thermal gradients may be controlled by design factors that alter the atmospheric energy exchange across the soil surface or that interrupt the geothermal heat field. 7 refs., 2 figs., 1 tab.

Cary, J.W.; Gee, G.W.; Whyatt, G.A.

1990-08-01

381

Water vapor distribution in the Venusian mesosphere from SPICAV/SOIR observations  

NASA Astrophysics Data System (ADS)

Water vapor is one of important gases in the Venus' atmosphere. The question why Venus is so much drier than Earth is crucial to understanding the evolution of the Venus atmosphere. H2O also play a significant role in the chemistry of the lower and middle atmosphere of Venus due to it involves in the sulfur oxidation cycle that produces H2SO4, and in active photochemistry above the clouds. Several in-situ experiments and ground-based observations allowed to measure water vapor abundance in the Venus atmosphere. The cloud-top H2O abundance has been observed by Pioneer Venus Orbiter Infrared Radiometer and Venera 15 Fourier Transform Spectrometer. The PV OIR instrument was found a substantial variation of H2O abundance in the equatorial cloud-top region shortly after the sub-solar point. Ground-based observations in microwaves also indicate a substantial variability. SPICAV VIS-IR is a part of SPICAV/SOIR experiment on Venus-Express. It is a single pixel spectrometer for the spectral range of 0.65-1.7 m based on AOTF (acousto-optical tunable filter) technology. Spectral resolution corresponds to 7.8 cm-1 for the short wavelength channel (0.65-1.1 m) and 5.2 cm-1 for the long wavelength channel (1-1.7 m). Resulting resolution power is 1400 at 1.4 m. The spectrometer sequentially measures spectra of reflected solar radiation from Venus on the dayside and the emitted Venus radiation in spectral "windows" on the night side. Based on 1.38 m band, H2O abundance above the clouds has been routinely retrieved for the dataset from the middle 2006 to the end of 2009 (VEX orbits 23-1300) taking into account multiple-scattering in the cloudy atmosphere. Altitude of cloud top level (65-73 km) corresponding =1 has been obtained from CO2 bands in the range of 1.4-1.65 m. Obtained H2O content varies inside 3-10 ppm and shows weak variations from orbit to orbit and with the latitude. In this report the local time and latitude distribution of H2O and long-term variability will be analyzed and main uncertainties will be discussed. The comparison of the morning and the evening observations at different latitudes with water vapor vertical profiles from SOIR solar occultation observations will be presented.

Fedorova, Anna; Korablev, Oleg; Bertaux, Jean-Loup; Montmessin, Franck; Belyaev, Denis; Mahieux, Arnaud; Vandaele, Ann-Carine

382

A Regional-Scale Assessment of Satellite Derived Precipitable Water Vapor Across The Amazon Basin  

NASA Technical Reports Server (NTRS)

Atmospheric water vapor is widely recognized as a key climate variable, linking an assortment of poorly understood and complex processes. It is a major element of the hydrological cycle and provides a mechanism for energy exchange among many of the Earth system components. Reducing uncertainty in our current knowledge of water vapor and its role in the climate system requires accurate measurement, improved modeling techniques, and long-term prediction. Satellites have the potential to satisfy these criteria, as well as provide high resolution measurements that are not available from conventional sources. The focus of this paper is to examine the temporal and mesoscale variations of satellite derived precipitable water vapor (PW) across the Amazon Basin. This region is pivotal in the functioning of the global climate system through its abundant release of latent heat associated with heavy precipitation events. In addition, anthropogenic deforestation and biomass burning activities in recent decades are altering the conditions of the atmosphere, especially in the planetary boundary layer. A physical split-window (PSW) algorithm estimates PW using images from the GOES satellites along with the NCEP/NCAR Reanalysis data that provides the first guess information. Retrievals are made at a three-hourly time step during daylight hours in the Amazon Basin and surrounding areas for the months of June and October in 1988 (dry year) and 1995 (wet year). Spatially continuous fields are generated 5 times daily at 12Z, 15Z, 18Z, 21Z, and 00Z. These fields are then averaged to create monthly and 3 hourly monthly grids. Overall, the PSW estimates PW reasonable well in the Amazon with MAE ranging from 3.0 - 9.0 mm and MAE/observed mean around 20% in comparison to radiosonde observations. The distribution of PW generally mimics that of precipitation. Maximum values (42 - 52 mm) are located in the Northwest whereas minimum values (18 - 27 mm) are found along Brazil's East coast. Aside from the East coast, PW has a stronger north-south gradient than that of rainfall. As for the temporal variation of PW, June (1988 and 1995) experiences a peak about 1400 local time, corresponding to a maximum in air temperature. In contrast, October (1988 and 1995) experiences a maximum early in the day, 1100 local time, with a gradual decrease toward nighttime.

DeLiberty, Tracy; Callahan, John; Guillory, Anthony R.; Jedlovec, Gary

2000-01-01

383

Corrosion of copper-based materials in gamma-irradiated air/water vapor systems  

SciTech Connect

Experiments were performed to investigate the atmospheric corrosion of copper-based materials in an irradiated air/water vapor system. The three materials investigated were oxygen-free copper (CDA-102), 7% aluminum-bronze (CDA-613), and 70-30 cupronickel (CDA-715). To support the corrosion studies, a number of irradiation studies were performed to characterize the gas phase radiation chemistry of the system. Both copper oxide and nitrate phases were identified as corrosion products depending on the dose rate, humidity and temperature. Uniform corrosion rates increased with temperature, humidity, and dose rate. A clear tie between the radiolytic products generated in the gas phase and the corrosion observed was established.

Reed, D.T.

1992-01-01

384

Corrosion of copper-based materials in gamma-irradiated air/water vapor systems  

SciTech Connect

Experiments were performed to investigate the atmospheric corrosion of copper-based materials in an irradiated air/water vapor system. The three materials investigated were oxygen-free copper (CDA-102), 7% aluminum-bronze (CDA-613), and 70-30 cupronickel (CDA-715). To support the corrosion studies, a number of irradiation studies were performed to characterize the gas phase radiation chemistry of the system. Both copper oxide and nitrate phases were identified as corrosion products depending on the dose rate, humidity and temperature. Uniform corrosion rates increased with temperature, humidity, and dose rate. A clear tie between the radiolytic products generated in the gas phase and the corrosion observed was established.

Reed, D.T.

1992-04-01

385

A water-vapor radiometer error model. [for ionosphere in geodetic microwave techniques  

NASA Technical Reports Server (NTRS)

The water-vapor radiometer (WVR) is used to calibrate unpredictable delays in the wet component of the troposphere in geodetic microwave techniques such as very-long-baseline interferometry (VLBI) and Global Positioning System (GPS) tracking. Based on experience with Jet Propulsion Laboratory (JPL) instruments, the current level of accuracy in wet-troposphere calibration limits the accuracy of local vertical measurements to 5-10 cm. The goal for the near future is 1-3 cm. Although the WVR is currently the best calibration method, many instruments are prone to systematic error. In this paper, a treatment of WVR data is proposed and evaluated. This treatment reduces the effect of WVR systematic errors by estimating parameters that specify an assumed functional form for the error. The assumed form of the treatment is evaluated by comparing the results of two similar WVR's operating near each other. Finally, the observability of the error parameters is estimated by covariance analysis.

Beckman, B.

1985-01-01

386

University of Wisconsin-Madison Participation in the International Water-Vapor Project (IHOP)  

NASA Technical Reports Server (NTRS)

This is the final report for NASA grant NAG-1-02057/University of Wisconsin-Madison/Dr. Henry E Revercomb, PI. This grant supported the University of Wisconsin-Madison participation in the International Water-Vapor Project (IHOP) experiment in May-June 2002. The upwelling thermal infrared emission from the surface and atmosphere over the U. S. Southern Great Plains was obtained from the NASA DC-8 with the Scanning High-resolution Interferometer Sounder (S-HIS) instrument, Analysis of the S-HIS radiances were used to obtain atmospheric temperature profiles below the aircraft. In a complementary manner, the downwelling thermal infrared emission at the surface was obtained by the University of Wisconsin Atmospheric Emitted Radiance Interferometer (AERI) instrument from a mobile research vehicle and used to profile the atmospheric boundary layer at the Homestead site. This report summarizes the observations of the S-HIS and AERI instruments during IHOP including validation against in situ observations.

Knuteson, Robert; Antonelli, Paolo; Best, Fred; Dutcher, Steve; Feltz, Wayne; Revercomb, Henry

2003-01-01

387

Comparison of a vapor explosion model to metal-water FCI tests  

SciTech Connect

Recent analyses indicate that the vapor explosion hazard may not be as severe as first thought when a hot molten liquid contacts a volatile coolant. However, benchmark data must be compared to available explosion models to verify this judgment. A series of calculations were recently performed to illustrate the predictive capabilities of the mechanistic vapor explosion model UWFCI. One needs to continually assess and compare relevant experimental data to understand the model limitations and where physical insights are revealed. The availability of reliable unambiguous vapor explosion data on explosion propagation/yield is very limited. Two recent experiments were chosen because they seem to represent the most carefully characterized explosion experiments available to date. The UWFCI vapor explosion model does a reasonably good job of predicting the correct scale of the peak explosion pressure and yield for both experiments.

Corradini, M.L. (Univ. of Wisconsin, Madison (United States))

1992-01-01

388

A Plant-Based Proxy for the Oxygen Isotope Ratio of Atmospheric Water Vapor  

NASA Astrophysics Data System (ADS)

Atmospheric water vapor is a major component of the global hydrological cycle, but the isotopic balance of vapor is largely unknown. It is shown here that the oxygen isotope ratio of leaf water in the epiphytic Crassulacean acid metabolism (CAM) plant Tillandsia usneoides (Spanish Moss) is controlled by the oxygen isotope ratio of atmospheric water vapor in both field and lab studies. Assuming that the leaf-water isotopic signature (and hence the atmospheric water vapor signature) is recorded in plant organic material, the atmospheric water vapor oxygen isotope ratios for Miami, Florida (USA) were reconstructed for several years from 1878 to 2005 using contemporary and herbarium specimens. T. usneoides ranges from Virginia, USA southwards through the tropics to Argentina, and the CAM epiphytic lifeform is widespread in other species. Therefore, epiphytes may be used to reconstruct the isotope ratio of atmospheric water for spatial scales that span over 60° of latitude and temporal scales that cover the last century of global temperature increase.

Helliker, B.

2007-12-01

389

Photothermal configuration applied to the study of water vapor permeability in biodegradable films under several water activities  

NASA Astrophysics Data System (ADS)

A photothermal configuration was used to determine the water vapor permeability of biodegradable films (nixtamalized corn pericarps). The films were obtained from corn grains boiled in an alkaline solution containing water and Ca(OH)2. Samples were exposed to saturated salt solutions with relative humidity in the range 7%-97%. The water vapor diffusion coefficient was determined as a function of relative humidity. The obtained coefficients agreed with data available in the literature. It was also found that the photoacoustic amplitude shows a linear dependence on the water activity, in agreement with our theoretical model.

Lopez-Bueno, G.; Martín-Martínez, E. San; Cruz-Orea, A.; Tomas, S. A.; Tufiño, M.; Sanchez, F.

2003-01-01

390

High-frequency measurements of atmospheric stable water vapor isotopes in the tropics (Sulawesi, Indonesia)  

NASA Astrophysics Data System (ADS)

Recent advances in cavity ring-down spectroscopy have enabled the continuous long-term measurement of atmospheric stable water vapor isotopes, which represent a powerful tool to investigate transport processes and sources of atmospheric water vapor. Here, we present continuous measurements of ?2H and ?18O of atmospheric water vapor made with a Picarro water vapor isotope analyzer (L2120-I, Picarro Inc.) from the roof top of our laboratory in Palu, Sulawesi, Indonesia. These are among the first known continuous high-frequency measurements made in the tropics, where water vapor plays a central role in the energy and water balance and where climate change is expected to significantly alter patterns of evapotranspiration and precipitation. We first characterize the accuracy and performance of the analyzer in terms of precision, memory effects and concentration dependency and assess its suitability for continuous remote long-term measurements. We then attempt to determine the source of atmospheric water vapor in Palu using measurements of ?2H and ?18O from precipitation and surface air, and explore the influence of wind speed, wind direction, atmospheric humidity and air temperature on variations in isotope ratios. The isotope analyzer was calibrated periodically using a standards delivery module in combination with a vaporizer included with the analyzer. From March to August 2011 the analyzer drift was <5.0 ‰ for ?2H and <1.2 ‰ for ?18O. Precision (one standard deviation) at a 60 s averaging time was 0.06 ‰ for ?2H and 0.03 ‰ for ?18O. From mid-April to late-June, 1-hour averages of surface air ?2H and ?18O ranged from -70 to -210 ‰ and from -15 to -35 ‰, respectively.

Brown, M.; Knohl, A.; Kreilein, H.; Zanotelli, D.; Rauf, A.; Barus, H.

2012-04-01

391

Stratospheric water vapor and climate: an uncertain future and the need for ongoing monitoring and measurement.  

NASA Astrophysics Data System (ADS)

Water vapor plays a key role in the radiative balance of the upper troposphere/lower stratosphere (UTLS), with changes in its concentration impacting on both local temperatures and the global-mean surface energy budget. We present results from state-of-the-art climate models participating in the fifth Coupled Model Intercomparison Project (CMIP5) which show that there is a large spread in projected changes in stratospheric water vapor under increased long-lived greenhouse gas concentrations. For the RCP8.5 scenario, which represents the least aggressive mitigation of future greenhouse gas emissions, all of the models analysed simulate an increase in tropical lower stratospheric water vapor over the 21st century, but the magnitude of this change varies by up to a factor of 5. This spread is shown to be related to differences in the simulated warming of the tropical tropopause and, given that methane oxidation plays only a minor role in this region, this implies that a significant portion of the stratospheric water vapor changes may be considered to be a climate feedback. This may therefore make an important contribution to the spread in climate sensitivity across CMIP5 models. To further demonstrate this, the effective radiative forcing associated with the change in stratospheric water vapor at the end of the century is calculated for each model. The uncertainty in future stratospheric water vapor change implied by the current generation of global climate models highlights the ongoing need for global monitoring of stratospheric water vapor, particularly in the UTLS region.

Maycock, A. C.; Hardiman, S. C.; Butchart, N.; Cagnazzo, C.

2012-12-01

392

Biases in Total Precipitable Water Vapor Climatologies from Atmospheric Infrared Sounder and Advanced Microwave Scanning Radiometer  

NASA Technical Reports Server (NTRS)

We examine differences in total precipitable water vapor (PWV) from the Atmospheric Infrared Sounder (AIRS) and the Advanced Microwave Scanning Radiometer (AMSR-E) experiments sharing the Aqua spacecraft platform. Both systems provide estimates of PWV over water surfaces. We compare AIRS and AMSR-E PWV to constrain AIRS retrieval uncertainties as functions of AIRS retrieved infrared cloud fraction. PWV differences between the two instruments vary only weakly with infrared cloud fraction up to about 70%. Maps of AIRS-AMSR-E PWV differences vary with location and season. Observational biases, when both instruments observe identical scenes, are generally less than 5%. Exceptions are in cold air outbreaks where AIRS is biased moist by 10-20% or 10-60% (depending on retrieval processing) and at high latitudes in winter where AIRS is dry by 5-10%. Sampling biases, from different sampling characteristics of AIRS and AMSR-E, vary in sign and magnitude. AIRS sampling is dry by up to 30% in most high-latitude regions but moist by 5-15% in subtropical stratus cloud belts. Over the northwest Pacific, AIRS samples conditions more moist than AMSR-E by a much as 60%. We hypothesize that both wet and dry sampling biases are due to the effects of clouds on the AIRS retrieval methodology. The sign and magnitude of these biases depend upon the types of cloud present and on the relationship between clouds and PWV. These results for PWV imply that climatologies of height-resolved water vapor from AIRS must take into consideration local meteorological processes affecting AIRS sampling.

Fetzer, Eric J.; Lambrigtsen, Bjorn H.; Eldering, Annmarie; Aumann, Hartmut H.; Chahine, Moustafa T.

2006-01-01

393

A Method For Retrieving Water Vapor Columnar Content And Aerosol Optical Thickness  

NASA Astrophysics Data System (ADS)

The capability to monitor and predict the physical characteristics of the atmosphere has been largely improved last decades. Aerosol optical thickness (AOT) and precipitable water vapor amount (W) are crucial atmospheric parameters in the understanding of atmospheric dynamics, as well as for the atmospheric correction of optical remote sensing images to be employed for land and water management. The objective of this work has been to adopt a methodology for measuring the water vapor and aerosol optical thickness in the atmospheric column by means of a Fieldspec Pro FR spectroradiometer. These measurements will be later useful for improving accuracy and helping to interpret remote sensing data, not only in the SPARC 2004 field campaign but for other future field campaigns aimed at land management. The methodology is based on two well-known techniques of sun photometry: the inversion of sun direct irradiance for AOT and split window, for precipitable water vapor. The direct solar irradiance were acquired simultaneously to Cimel CE318 NE and Microtops II measurements, working collocated during the SPARC 2004 campaign held at Barrax (Spain) in 2004 July. The obtained measurements have been compared to simultaneous retrievals from these collocated sun photometers. The results so far obtained showed the feasibility of this instrument to be employed for columnar water vapor and aerosol optical thickness retrieval. For water vapor, the deviation were found to be well within the estimated Cimel and Microtops uncertainty, stated as 10%.

Bassani, C.; Cavalli, R. M.; Estellés, V.; Gómez-Amo, J. L.; Martínez-Lozano, J. A.; Pignatti, S.; Utrillas, M. P.

2006-08-01

394

Models of the atmospheric water vapor budget for the Texas HIPLEX area: by Steven Francis Williams.  

E-print Network

boundaries. c. Transport of center xraPor trrorcgh ho. ' zontal. boundaries Term (3) in Fq. (5) can be integrated ov r the area hown in Fig. l. The vertical transport of. wai. cr vapor tnrcuah one horizontal boundary can ce expressed as: (T ), = (qP w... and vertical trzu&sport of wai:er vapor, local rate-of-change in the to" al mas- of water vapor, and ti'. e re. . idual term . or, several stratifications. Due to the small sample size standard. deviation" of ths average prof iles are not pres nt d. Fmch...

Williams, Steven Francis

2012-06-07

395

Flux of water vapor in the terrestrial stratosphere and in the Martian atmosphere  

NASA Technical Reports Server (NTRS)

A summary of the terrestrial satellite data is presented. The observations indicate that at equatorial latitudes, relatively dry air is introduced at the tropopause and carried to the upper stratosphere. At that altitude, any methane present in the ascending air mass is oxidized photochemically into water vapor. This vapor is eventually transported to high latitudes, where it is carried to the lower stratosphere by the descending leg of the diabatic circulation. The Pressure Modulator Infrared Radiometer instrument aboard the Mars Observer should provide a comparable picture of vapor transport in the martian atmosphere.

Leovy, Conway; Hitchman, Matthew; Mccleese, Daniel J.

1988-01-01