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1

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

2

Current status of the upcoming water vapor data sets from SAGE II and SAGE III experiments  

NASA Astrophysics Data System (ADS)

The multi-year water vapor data set (version 5.9, covering January 1986 through May 1991) from the Stratospheric Aerosol and Gas Experiment II (SAGE II) played an important role in the SPARC Assessment of Upper Tropspheric and Stratospheric Water Vapor (WMO/TD No.1043, SPARC Report No.2; December 2000). Since then, revised SAGE II water vapor data sets, version 6.0 and version 6.1, covering an extended period of 16 years (1984 through 2000) were released in July 2000 and October 2001. Following extensive studies, a newly improved SAGE II water vapor data set (version 6.2) is currently being processed. Using the updated information of spectral channel location and spectral bandwidth together with an improved aerosol model, this upcoming SAGE II water vapor data set has achieved significant improvements regarding the previously existing dry-bias in the lower to middle stratosphere. The Stratospheric Aerosol and Gas Experiment III (SAGE III), an improved extension of SAGE II and part of NASA's Earth Observing System (EOS) program, was succesfully launched aboard Russian METEOR 3M-1 platform in December 2001. The data sets of aerosol, ozone and nitrogen dioxide from SAGE III were released in November 2002. Subsequent archival of SAGE III water vapor measurements will take place following successful assessment and validation efforts. The purpose of this paper is to present the current status of the upcoming water vapor data sets to be released from both SAGE II and SAGE III experiments. Examples will be shown to demonstrate the improvements of version 6.2 SAGE II water vapor profiles through comparisons with coincident measurements from baloon-borne frost-point hygrometer and HALOE satellite experiment. Preliminary assessment of water vapor profiles retrieved from SAGE III experiment will also be discussed.

Chiou, E. W.; Chu, W. P.; Thomason, L. W.; Burton, S.

2003-04-01

3

Increases in middle atmospheric water vapor as observed by the Halogen Occultation Experiment and the ground-based Water Vapor Millimeter-wave Spectrometer from 1991 to 1997  

Microsoft Academic Search

Water vapor measurements made by the Halogen Occultation Experiment (HALOE) from 1991 to 1997 are compared with ground-based observations by the Water Vapor Millimeter-wave Spectrometers (WVMS) taken from 1992 to 1997 at Table Mountain, California (34.4øN, 242.3øE), and at Lauder, New Zealand (45.0øS, 169.7øE). The HALOE measurements show that an upward trend in middle atmospheric water vapor is present at

Gerald E. Nedoluha; Richard M. Bevilacqua; R. Michael Gomez; David E. Siskind; Brian C. Hicks; James M. Russell; Brian J. Connor

1998-01-01

4

NASA Experiment on Tropospheric-Stratospheric Water Vapor Transport in the Intertropical Convergence Zone  

NASA Technical Reports Server (NTRS)

The following six papers report preliminary results obtained from a field experiment designed to study the role of tropical cumulo-nimbus clouds in the transfer of water vapor from the troposphere to the stratosphere over the region of Panama. The measurements were made utilizing special NOAA enhanced IR satellite images, radiosonde-ozonesondes and a NASA U-2 aircraft carrying. nine experiments. The experiments were provided by a group of NASA, NOAA, industry, and university scientists. Measurements included atmospheric humidity, air and cloud top temperatures, atmospheric tracer constituents, cloud particle characteristics and cloud morphology. The aircraft made a total of eleven flights from August 30 through September 18, 1980, from Howard Air Force Base, Panama; the pilots obtained horizontal and vertical profiles in and near convectively active regions and flew around and over cumulo-nimbus towers and through the extended anvils in the stratosphere. Cumulo-nimbus clouds in the tropics appear to play an important role in upward water vapor transport and may represent the principal source influencing the stratospheric water vapor budget. The clouds provide strong vertical circulation in the troposphere, mixing surface air and its trace materials (water vapor, CFM's sulfur compounds, etc.) quickly up to the tropopause. It is usually assumed that large scale mean motions or eddy scale motions transport the trace materials through the tropopause and into the stratosphere where they are further dispersed and react with other stratospheric constituents. The important step between the troposphere and stratosphere for water vapor appears to depend upon the processes occurring at or near the tropopause at the tops of the cumulo-nimbus towers. Several processes have been sugested: (1) The highest towers penetrate the tropopause and carry water in the form of small ice particles directly into the stratosphere. (2) Water vapor from the tops of the cumulonimbus clouds is transported somehow through the tropopause, the vapor pressure being controlled by the temperature at the tops of the clouds; the dryness of the stratosphere could be explained if most of the transport occurs in connection with very high clouds in regions with very high and cold tropopause. (3) Cumulo-nimbus anvils act as terrestrial-radiation shields allowing the ice particle temperatures near cloud tops to cool radiatively below the supersaturation point; this cooling would cause a vapor deposition on the ice particles which will settle out and thus act as water scavengers. The experiment was designed to collect information on these detailed physical processes near and above the tropopause in order to assess their importance and the role they play in controlling stratospheric water vapor humidity.

Page, William A.

1982-01-01

5

Tropospheric water vapor and aerosol measurements obtained during LASE validation experiment  

SciTech Connect

The Lidar Atmospheric Sensing Experiment (LASE) is a Differential Absorption Lidar (DIAL) system flown on the NASA ER-2 aircraft to remotely measure distributions of tropospheric water vapor, aerosols, and clouds. LASE was developed at the NASA Langley Research Center (LaRC) to demonstrate autonomous operation of a DIAL system from a high-altitude aircraft as an important step towards developing a spaceborne DIAL system. LASE uses a double pulsed Ti:sapphire laser operating in the 815-nm absorption band of water vapor to generate the on- and off-line DIAL laser pulses. The system has two avalanche photodiode detectors and three signal digitizers to preserve the lidar backscatter signals over a large dynamic range. In September 1995, LASE completed a comprehensive validation program at the NASA Wallops Flight Facility. The system was flown on the ER-2 during ten flights for a total of 60 hours. LASE measurements of tropospheric water vapor were compared with other remote and in situ measurements of water vapor from the ground and from aircraft which underflew the ER-2. Besides making intercomparisons with a number of water vapor sensors, this experiment incorporated a number of case studies related to atmospheric events including flights over and around Hurricane Luis over the Atlantic ocean, sea breeze development along the east coast of Virginia, and stratosphere-troposphere exchange. This paper presents data taken during this field experiment that demonstrate the accuracy of LASE for tropospheric water vapor measurements. The paper also discusses results from several of the atmospheric case studies conducted during this experiment and the potential future uses of LASE.

Browell, E.V.; Ismail, S.; Hall, W.M.; Moore, A.S. [and others

1996-10-01

6

Seasonal variation of water vapor in the lower stratosphere observed in Halogen Occultation Experiment data  

Microsoft Academic Search

The seasonal cycle of water vapor in the lower stratosphere is studied based on Halogen Occultation Experiment (HALOE) satellite observations spanning 1991-2000. The seasonal cycle highlights fast, quasi-horizontal transport between tropics and midlatitudes in the lowermost stratosphere (near isentropic levels -380-420 K), in addition to vertical propagation above the equator (the tropical \\

William J. Randel; Fei Wu; Andrew Gettelman; J. M. Russell; Joseph M. Zawodny; Samuel J. Oltmans

2001-01-01

7

Algorithms and sensitivity analyses for stratospheric aerosol and gas experiment II water vapor retrieval  

SciTech Connect

This paper provides a detailed description of the current operational inversion algorithm for the retrieval of water vapor vertical profiles from the Stratospheric Aerosol and Gas Experiment II (SAGE II) occultation data at the 0.94-[mu]m wavelength channel. This algorithm is different from the algorithm used for the retrieval of the other species such as aerosol, ozone, and nitrogen dioxide because of the nonlinear relationship between the concentration versus the broad band absorption characteristics of water vapor. Included in the discussion of the retrieval algorithm are problems related to the accuracy of the computational scheme, accuracy of the removal of other interfering species, and the expected uncertainty of the retrieved profile. A comparative analysis on the computational schemes used for the calculation of the water vapor transmission at the 0.94-[mu]m wavelength region is presented. Analyses are also presented on the sensitivity of the retrievals to interferences from the other species which contribute to the total signature as observed at the 0.94-[mu]m wavelength channel on SAGE II instrument. Error analyses of the SAGE II water vapor retrieval is shown, indicating that good quality water vapor data are being produced by the SAGE II measurements. 27 refs., 10 figs., 1 tab.

Chu, W.P.; Thomason, L.W.; Buglia, J.J.; McCormick, M.P.; McMaster, L.M. (NASA Langley Research Center, Hampton, VA (United States)); Chiou, E.W.; Larsen, J.C. (STX Corp., Hampton, VA (United States)); Rind, D. (Goddard Space Flight Center, New York, NY (United States)); Oltmans, S. (NOAA/Climate Monitoring and Diagnostic Lab., Boulder, CO (United States))

1993-03-20

8

A revised water vapor product for the Stratospheric Aerosol and Gas Experiment (SAGE) II version 6.2 data set  

Microsoft Academic Search

The Stratospheric Aerosol and Gas Experiment (SAGE) II water vapor retrieval process has been updated to reflect a new understanding of the instrument performance. Primarily, this is reflected in a shifted spectral response for the primary water channel near 935 nm for the period after January 1986. In addition, the water vapor and ozone spectroscopy, aerosol clearing process, and error

Larry W. Thomason; Sharon P. Burton; Nina Iyer; Joseph M. Zawodny; John Anderson

2004-01-01

9

Annual variations of water vapor in the stratosphere and upper troposphere observed by the Stratospheric Aerosol and Gas Experiment II  

NASA Technical Reports Server (NTRS)

Data collected by the Stratospheric Aerosol and Gas Experiment II are presented, showing annual variations of water vapor in the stratosphere and the upper troposphere. The altitude-time cross sections of water vapor were found to exhibit annually repeatable patterns in both hemispheres, with a yearly minimum in water vapor appearing in both hemispheres at about the same time, supporting the concept of a common source for stratospheric dry air. A linear regression analysis was applied to the three-year data set to elucidate global values and variations of water vapor ratio.

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

1993-01-01

10

Raman lidar and sun photometer measurements of aerosols and water vapor during the ARM RCS experiment  

NASA Technical Reports Server (NTRS)

The first Atmospheric Radiation Measurement (ARM) Remote Cloud Study (RCS) Intensive Operations Period (IOP) was held during April 1994 at the Southern Great Plains (SGP) Cloud and Radiation Testbed (CART) site near Lamont, Oklahoma. This experiment was conducted to evaluate and calibrate state-of-the-art, ground based remote sensing instruments and to use the data acquired by these instruments to validate retrieval algorithms developed under the ARM program. These activities are part of an overall plan to assess general circulation model (GCM) parameterization research. Since radiation processes are one of the key areas included in this parameterization research, measurements of water vapor and aerosols are required because of the important roles these atmospheric constituents play in radiative transfer. Two instruments were deployed during this IOP to measure water vapor and aerosols and study their relationship. The NASA/Goddard Space Flight Center (GSFC) Scanning Raman Lidar (SRL) acquired water vapor and aerosol profile data during 15 nights of operations. The lidar acquired vertical profiles as well as nearly horizontal profiles directed near an instrumented 60 meter tower. Aerosol optical thickness, phase function, size distribution, and integrated water vapor were derived from measurements with a multiband automatic sun and sky scanning radiometer deployed at this site.

Ferrare, R. A.; Whiteman, D. N.; Melfi, S. H.; Evans, K. D.; Holben, B. N.

1995-01-01

11

Overview of the Stratospheric Aerosol and Gas Experiment II water vapor observations - Method, validation, and data characteristics  

NASA Technical Reports Server (NTRS)

Results are presented of water vapor observations in the troposphere and stratosphere performed by the Stratospheric Aerosol and Gas Experiment II solar occultation instrument, and the analysis procedure, the instrument errors, and data characteristics are discussed. The results are compared with correlative in situ measurements and other satellite data. The features of the data set collected between 1985 and 1989 include an increase in middle- and upper-tropospheric water vapor during northern hemisphere summer and autumn; minimum water vapor values of 2.5-3 ppmv in the tropical lower stratosphere; slowly increasing water vapor values with altitude in the stratosphere, reaching 5-6 ppmv or greater near the stratopause; extratropical values with minimum profile amounts occurring above the conventionally defined tropopause; and higher extratropical than tropical water vapor values throughout the stratosphere except in locations of possible polar stratospheric clouds.

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

1993-01-01

12

Water Vapor Protocol  

NSDL National Science Digital Library

The purpose of this activity is to measure the total precipitable water vapor (column water vapor) in the atmosphere above an observer's site. Students point a GLOBE/GIFTS water vapor instrument at the sun and record the voltage readings from a digital voltmeter. They observe sky conditions near the Sun and perform the Cloud Protocols. Intended outcomes are that students understand the concept that the atmosphere prevents some of the sun's light from reaching Earth's surface, how water vapor measurements relate to the hydrologic cycle, and how greenhouse gases, such as water vapor, play an important role in weather and climate. Supporting background materials for both student and teacher are included.

The GLOBE Program, UCAR (University Corporation for Atmospheric Research)

2003-08-01

13

Stratospheric water vapor feedback.  

PubMed

We show here that stratospheric water vapor variations play an important role in the evolution of our climate. This comes from analysis of observations showing that stratospheric water vapor increases with tropospheric temperature, implying the existence of a stratospheric water vapor feedback. We estimate the strength of this feedback in a chemistry-climate model to be +0.3 W/(m(2)?K), which would be a significant contributor to the overall climate sensitivity. One-third of this feedback comes from increases in water vapor entering the stratosphere through the tropical tropopause layer, with the rest coming from increases in water vapor entering through the extratropical tropopause. PMID:24082126

Dessler, A E; Schoeberl, M R; Wang, T; Davis, S M; Rosenlof, K H

2013-11-01

14

Stratospheric water vapor feedback  

PubMed Central

We show here that stratospheric water vapor variations play an important role in the evolution of our climate. This comes from analysis of observations showing that stratospheric water vapor increases with tropospheric temperature, implying the existence of a stratospheric water vapor feedback. We estimate the strength of this feedback in a chemistry–climate model to be +0.3 W/(m2?K), which would be a significant contributor to the overall climate sensitivity. One-third of this feedback comes from increases in water vapor entering the stratosphere through the tropical tropopause layer, with the rest coming from increases in water vapor entering through the extratropical tropopause. PMID:24082126

Dessler, A. E.; Schoeberl, M. R.; Wang, T.; Davis, S. M.; Rosenlof, K. H.

2013-01-01

15

ELF and ALEX SURF WINTER WAVES: Lidar Intercomparison of Aerosol and Water Vapor Measurements in the Baltimore-Washington Metropolitan Area During the Winter Water Vapor Validation Experiments (WAVES) 2008 campaign  

Microsoft Academic Search

Elastic and Raman lidar measurements were conducted to measure the vertical distribution of aerosols and water vapor during the Water Vapor Validation Experiments (WAVES) 2008 campaign by the University of Maryland Baltimore County (UMBC) Atmospheric Lidar Group at UMBC, at the same time as measurements at Howard University's Beltsville Research Station (26.5 km distant). The lidar profiles of atmospheric water

R. Delgado; M. Weldegaber; R. C. Wilson; W. McMillan; K. J. McCann; M. Woodman; B. Demoz; M. Adam; R. Connell; D. Venable; E. Joseph; S. Rabenhorst; L. Twigg; T. McGee; D. N. Whiteman; R. M. Hoff

2008-01-01

16

A comparison of the Stratospheric Aerosol and Gas Experiment II tropospheric water vapor to radiosonde measurements  

SciTech Connect

Upper tropospheric Stratospheric Aerosol and Gas Experiment II (SAGE II) water vapor observations are compared to correlative radiosonde observations and radiosonde based climatologies. The SAGE II 1987 monthly zonal mean water vapor climatology is compared to both the Global Atmospheric Circulation Statistics (1963-1973) climatology and to the 1987 radiosonde climatology. The clear sky SAGE II climatology is found to be approximately half the level of both the clear/cloudy sky radiosonde climatologies. To determine whether this is realistic for these two different climatologies or includes additional observational and instrumental biases, the authors took the 1987 radiosonde data set and identified approximately 800 correlative profile pairs. The observational biases inherent to SAGE II and the radiosondes produce a set of profile pairs characteristic of clear sky, land conditions. A critical review of the radiosonde measurement capability was carried out to establish the operating range and accuracy in the upper troposphere. The authors show that even with tight coincidence criterion, the quality of the profile pair comparisons varies considerably because of strong water vapor variability occurring on small time and space scales. Annual zonal means calculated from the set of profile pairs again finds SAGE II significantly drier in many latitude bands. Resolving the radiosonde data base by hygrometer type shows this to be true for all hygrometers except for the thin film capacitive type (Vaisala Humicap). For this hygrometer, between 4.5 and 6.5 km SAGE II is drier by approximately 25.%, and from 8.5 to 11.5 km they are nearly equivalent when global annual means are compared. The good agreement with the Vaisala Humicap, currently the most accurate and responsive hygrometer in operational use, suggests existing radiosonde climatologies contain a significant moist bias in the upper troposphere. 31 refs., 16 figs., 6 tabs.

Larsen, J.C.; Chiou, E.W. (Hughes STX Corp., Hampton, VA (United States)); Chu, W.P.; McCormick, M.P.; McMaster, L.R. (NASA Langley Research Center, Hampton, VA (United States)); Oltmans, S. (NOAA Climate Modeling and Diagnostic Lab., Boulder, CO (United States)); Rind, D. (NASA Goddard Inst. for Space Studies, New York, NY (United States))

1993-03-20

17

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

NASA Technical Reports Server (NTRS)

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

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

1974-01-01

18

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

19

A comparison of the Stratospheric Aerosol and Gas Experiment II tropospheric water vapor to radiosonde measurements  

NASA Technical Reports Server (NTRS)

Results are presented of a comparison beteen observations of the upper-tropospheric water vapor data obtained from the Stratospheric Aerosol and Gas Experiment II (SAGE II) instrument and radiosonde observations for 1987 and radiosonde-based climatologies. Colocated SAGE II-radiosonde measurement pairs are compared individually and in a zonal mean sense. A straight comparison of monthly zonal means between SAGE II and radiosondes for 1987 and Global Atmospheric Statistics (1963-1973) indicates that the clear-sky SAGE II climatology is approximately half the level of clear/cloudy sky of both radiosonde climatologies. Annual zonal means calculated from the set of profile pairs again showed SAGE II to be significantly drier in many altitude bands.

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

1993-01-01

20

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

21

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

22

Cesar water vapor, aerosol  

E-print Network

Fig ure A: Cesar water vapor, aerosol and Clo ud lidar (Cae li) Fig ure B: IIR 3-channe l composite) Fig ure C: Lidar returns on 13 Sept. 2006 from Caeli (To p) and CALIPSO (bottom) 1) KNMI Royal aerosol property profiles measured with lidar M. de Graaf 1,2 , D.P. Donovan 1 , A. Apituley 2 , K

Graaf, Martin de

23

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

24

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

25

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

26

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. Quicktime is required to view the clip.

2010-08-27

27

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  

SciTech Connect

This paper presents a comparison of the stratospheric water vapor measurements made by the satellite-borne sensors the Stratospheric Aerosol and Gas Experiment II (SAGE II), the Nimbus 7 Limb Infrared Monitor of the Stratosphere (LIMS), and the Spacelab 3 Atmospheric Trace Molecule Spectroscopy (ATMOS) experiment. LIMS obtained data for 7 months between November 1978 and May 1979; ATMOS was carried on Shuttle and observed eight profiles from April 30 to May 6, 1985 at approximately 30[degrees]N and 50[degrees]S; and, SAGE II continues to make measurements since its launch in October 1984. For both 30[degrees]N and 50[degrees]S in May, the comparisons between SAGE II and ATMOS show agreement within the estimated combined uncertainty of the two experiments. Several important features identified by LIMS observations have been confirmed by SAGE II: a well-developed hygropause in the lower stratosphere at low- to mid-latitudes, a poleward latitudinal gradient, increasing water vapor mixing ratios with altitude in the tropics, and the transport of dry lower stratospheric water vapor upward and southward in May, and upward and northward in November. A detailed comparative study also indicates that the two previously suggested corrections for LIMS, a correction in tropical lower stratosphere due to a positive temperature bias and the correction above 28 km based on improved emissivities will bring LIMS measurements much closer to those of SAGE II. The only significant difference occurs at high southern latitudes in May below 18 km, where LIMS measurements are 2-3 ppmv greater. It should be noted that LIMS observations are from 16 to 50 km, ATMOS from 14 to 86 km, and SAGE II from mid-troposphere to 40 km. With multiyear coverage, SAGE II observations should be useful for studying tropospheric-stratospheric exchange, for stratospheric transport, and for preparing water vapor climatologies for the stratosphere and the upper troposphere. 32 refs., 14 figs., 2 tabs.

Chiou, E.W.; Larsen, J.C. (Hughes STX Corp., Hampton, VA (United States)); McCormick, M.P.; McMaster, L.R.; Chu, W.P. (NASA Langley Research Center, Hampton, VA (United States)); Rind, D. (NASA Goddard Inst. for Space Studies, New York, NY (United States)); Oltmans, S. (NOAA Climate Monitoring and Diagnostic Lab., Boulder, CO (United States))

1993-03-20

28

SOFIA Water Vapor Monitor Design  

NASA Technical Reports Server (NTRS)

The SOFIA Water Vapor Monitor (WVM) is a heterodyne radiometer designed to determine the integrated amount of water vapor along the telescope line of sight and directly to the zenith. The basic technique that was chosen for the WVM uses radiometric measurements of the center and wings of the 183.3 GHz rotational line of water to measure the water vapor. The WVM reports its measured water vapor levels to the aircraft Mission Controls and Communication System (MCCS) while the SOFIA observatory is in normal operation at flight altitude. The water vapor measurements are also available to other scientific instruments aboard the observatory. The electrical, mechanical and software design of the WVM are discussed.

Cooper, R.; Roellig, T. L.; Yuen, L.; Shiroyama, B.; Meyer, A.; Devincenzi, D. (Technical Monitor)

2002-01-01

29

Advanced Raman water vapor lidar  

Microsoft Academic Search

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

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

1992-01-01

30

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

31

Electrical Breakdown in Water Vapor  

SciTech Connect

In this paper investigations of the voltage required to break down water vapor are reported for the region around the Paschen minimum and to the left of it. In spite of numerous applications of discharges in biomedicine, and recent studies of discharges in water and vapor bubbles and discharges with liquid water electrodes, studies of the basic parameters of breakdown are lacking. Paschen curves have been measured by recording voltages and currents in the low-current Townsend regime and extrapolating them to zero current. The minimum electrical breakdown voltage for water vapor was found to be 480 V at a pressure times electrode distance (pd) value of around 0.6 Torr cm ({approx}0.8 Pa m). The present measurements are also interpreted using (and add additional insight into) the developing understanding of relevant atomic and particularly surface processes associated with electrical breakdown.

Skoro, N.; Maric, D.; Malovic, G.; Petrovic, Z. Lj. [Institute of Physics, University of Belgrade, Pregrevica 118, 11080 Belgrade (Serbia); Graham, W. G. [Centre for Plasma Physics, School of Mathematics and Physics, Queens University Belfast, BT7 1NN (United Kingdom)

2011-11-15

32

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

33

Terahertz Spectroscopy of Water Vapors, Chemical Vapors and Ionized Air  

NASA Astrophysics Data System (ADS)

In the past, a few research groups have demonstrated that terahertz spectroscopy could be a useful tool for the identification of chemicals. However most of those demonstrations have been done with solid-phase or liquid-phase chemicals. There are little demonstrations for the detection and identification of chemicals in the gas-phase, as it is very difficult in part due to the presence of water-absorption lines in the terahertz frequency range. As the water absorption lines predominate in the 0.1 - 2THz spectral range, and can interfere with already weak terahertz signatures generated by chemical vapors, it is often very hard to obtain meaningful terahertz spectrum of chemical vapor. Regardless we recently have been able to obtain some terahertz spectra of chemical vapors and ionized air produced by several different ionization sources, including corona discharge and nuclear isotopes. Throughout data analysis we learned that water molecules, nitrogen and oxygen molecules play very important roles in these terahertz spectra. In this presentation we will discuss our experiments and the roles of these molecules.

Graber, Benjamin; Tao, Rongjia; Wu, Dong Ho

2013-03-01

34

Raman water vapor lidar calibration  

Microsoft Academic Search

We show here new results of a Raman LIDAR calibration methodology effort putting emphasis in the assessment of the cross-section ratio between water vapor and nitrogen by the use of a calibrated NIST traceable tungsten lamp. Therein we give a step by step procedure of how to employ such equipment by means of a mapping\\/scanning procedure over the receiving optics

E. Landulfo; R. F. da Costa; A. S. Torres; F. J. S. Lopes; D. N. Whiteman; D. D. Venable

2009-01-01

35

4, 83278355, 2004 Water vapor LIDAR  

E-print Network

ACPD 4, 8327­8355, 2004 Water vapor LIDAR measurements during stratospheric intrusions P. D and Physics Discussions Analysis of water vapor LIDAR measurements during the MAP campaign: evidence of sub Commons License. 8327 #12;ACPD 4, 8327­8355, 2004 Water vapor LIDAR measurements during stratospheric

Paris-Sud XI, Université de

36

Meteorological water vapor Raman lidar: advances  

Microsoft Academic Search

We present the design and preliminary results of a water vapor Raman lidar, developed explicitly for meteorological applications. The lidar was designed for Meteoswiss as a fully automated, eye-safe instrument for routine water vapor measurements in the troposphere. The lidar is capable of day and nighttime vertical profiling of the tropospheric water vapor with 15 to 30 min temporal resolution.

T. Dinoev; P. Ristori; Y. Arshinov; S. Bobrovnikov; I. Serikov; B. Calpini; H. van den Bergh; V. Simeonov

2006-01-01

37

Profiling of atmospheric water vapor with MIR and LASE  

Microsoft Academic Search

Concurrent measurements of atmospheric water vapor profiles were conducted over the Atlantic Ocean on September 25, 1995 with both the Millimeter-wave Imaging Radiometer (MIR) and Lidar Atmospheric Sounding Experiment (LASE) on board the NASA ER-2 aircraft. LASE provides high precision measurements of both aerosol backscatter and water vapor profiles; aerosol backscatter has a vertical resolution of 60 m while the

James R. Wang; Paul Racette; M. E. Triesky; E. V. Browell; S. Ismail; L. A. Chang

2002-01-01

38

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

39

Exchange of tritium between water and vapor  

SciTech Connect

Isotopic exchange was measured by filling beakers with waters of different isotopic compositions and allowing them to equilbrate via the vapor phase in plexiglas boxes. Tritium analyses were performed prior to and after the experiment. The waters ranged in [delta]D from -105 to +27 per mil, and from -13.0 to +9 per mil in [delta][sup 18]O; tritium contents ranged from <10 pCi/l to nearly 320,000 pCi/l. Results are reported for three- and two-beaker systems; a bubble exchange experiment was also conducted. 3 tabs.

Ingraham, N.L.

1993-01-01

40

Water vapor diffusion membrane development  

NASA Technical Reports Server (NTRS)

An application of the water vapor diffusion technique is examined whereby the permeated water vapor is vented to space vacuum to alleviate on-board waste storage and provide supplemental cooling. The work reported herein deals primarily with the vapor diffusion-heat rejection (VD-HR) as it applies to the Space Shuttle. A stack configuration was selected, designed and fabricated. An asymmetric cellulose acetate membrane, used in reverse osmosis application was selected and a special spacer was designed to enhance mixing and promote mass transfer. A skid-mount unit was assembled from components used in the bench unit although no attempt was made to render it flight-suitable. The operating conditions of the VD-HR were examined and defined and a 60-day continuous test was carried out. The membranes performed very well throughout the test; no membrane rupture and no unusual flux decay was observed. In addition, a tentative design for a flight-suitable VD-HR unit was made.

Tan, M. K.

1977-01-01

41

Airborne LIDAR Measurements of Water Vapor, Ozone, Clouds, and Aerosols in the Tropics Near Central America During the TC4 Experiment  

NASA Technical Reports Server (NTRS)

Large scale distributions of ozone, water vapor, aerosols, and clouds were measured throughout the troposphere by two NASA Langley lidar systems on board the NASA DC-8 aircraft as part of the Tropical Composition, Cloud, and Climate Coupling Experiment (TC4) over Central and South America and adjacent oceans in the summer of 2007. Special emphasis was placed on the sampling of convective outflow and transport, sub-visible cirrus clouds, boundary layer aerosols, Saharan dust, volcanic emissions, and urban and biomass burning plumes. This paper presents preliminary results from this campaign, and demonstrates the value of coordinated measurements by the two lidar systems.

Kooi, Susan; Fenn, Marta; Ismail, Syed; Ferrare, Richard; Hair, John; Browell, Edward; Notari, Anthony; Butler, Carolyn; Burton, Sharon; Simpson, Steven

2008-01-01

42

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.

2012-08-03

43

Cell for electrolysis of water vapor  

NASA Technical Reports Server (NTRS)

Electrolytic cells regenerate oxygen from the water vapor in the air of closed-loop life-support system and remove water vapor from air circulated through them. Water is converted into oxygen and hydrogen; the oxygen is returned to the air, the hydrogen is vented or used elsewhere.

Celino, V. A.; Roebelen, G.

1972-01-01

44

Effects of vertical distribution of water vapor and temperature on total column water vapor retrieval error  

Microsoft Academic Search

The physically based total column water vapor retrieval algorithm of Wentz (1992) is tested for sensitivity to realistic vertical distributions of temperature and water vapor. The spatial pattern of systematic retrieval error of total column water vapor due to this sensitivity is simulated using the European Center for Medium Range Weather Forecasts (ECMWF) monthly averaged temperature and humidity fields. Effects

Jielun Sun

1993-01-01

45

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

46

X-ray-induced water vaporization  

SciTech Connect

We present quantitative evidence for x-ray-induced water vaporization: water is vaporized at a rate of 5.5 pL/s with the 1-A-wavelength x-ray irradiation of {approx}0.1 photons per A{sup 2}; moreover, water vapor is reversibly condensed during pauses in irradiation. This result fundamentally suggests that photoionization induces vaporization. This phenomenon is attributed to surface-tension reduction by ionization and would be universally important in radiological and electrohydrodynamic situations.

Weon, B. M.; Lee, J. S.; Je, J. H. [X-ray Imaging Center, Department of Materials Science and Engineering,Pohang University of Science and Technology, San 31, Pohang 790-784 (Korea, Republic of); Fezzaa, K. [X-ray Science Division, Advanced Photon Source, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439 (United States)

2011-09-15

47

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

48

Water Vapor Raman LIDAR Within the Ndsc  

Microsoft Academic Search

This work is a joint effort to provide best water vapor measurements in the upper troposphere lower stratosphere within the NDSC. It is only recently that NDSC decided to include water vapor lidar measurements as a standard tool. While the NDSC project is centered on the stratosphere, detection of the Raman measurements is improved to reach the highest altitude. Here

Philippe Keckhut; Gelsomina Pappalardo; Arnoud Apituley; Fernando Congeduti; Thierry Leblanc; Franz Immler; Marion Muller; Choo Hie Lee; Laurent Robert; Valentin Simeonov; Geraint Vaughan; Dave Whiteman

2004-01-01

49

Comparison Of Measurments Of Atmospheric Water Vapor  

NASA Technical Reports Server (NTRS)

Report presents experimental intercomparison among measurements by four spectrometric instruments for determining concentration of atmospheric water vapor. Three instruments ground-based and needed to provide independent data to calibrate and validate measurements taken by fourth instrument, which is airborne visible/infrared imaging spectrometer (AVIRIS). Remote down-looking instruments like AVIRIS increases accuracy and coverage of water-vapor measurements.

Bruegge, Carol J.; Conel, James E.; Margolis, Jack S.; Green, Robert O.; Toon, Geoffrey C.; Carrere, Veronique; Holm, Ronald G.; Hoover, Gordon L.

1994-01-01

50

The applicability of a scanning Raman lidar for measurements of aerosols and water vapor  

Microsoft Academic Search

Assessing atmospheric water vapor measurements to the level of accuracy required for improving atmospheric radiation parameterizations has been difficult to achieve. This thesis describes how a new sensor, the NASA\\/GSFC Scanning Raman Lidar (SRL), is used to improve assessments of water vapor measurements. Water vapor profiles measured at night by this lidar during two field experiments are compared with those

Richard Anthony Ferrare

1997-01-01

51

Water Vapor Distribution in Protoplanetary Disks  

NASA Astrophysics Data System (ADS)

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 Ly? photons, since the Ly? 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 extended distribution of warm water vapor, while dust growth and settling tends to reduce the amount of warm water vapor. Based on typical assumptions regarding the elemental oxygen abundance and the water chemistry, the column density of warm water vapor can be as high as 1022 cm-2. A small amount of hot water vapor with temperature higher than ~300 K exists in a more extended region in the upper atmosphere of the disk. Cold water vapor with temperature lower than 100 K is distributed over the entire disk, produced by photodesorption of the water ice.

Du, Fujun; Bergin, Edwin A.

2014-09-01

52

Tropical upper tropospheric water vapor distribution  

NASA Astrophysics Data System (ADS)

Water vapor is a powerful greenhouse gas and its fast response to temperature makes it a good candidates for creating feedback mechanisms that could modify global climate substantially. For one of the most important climate system on the Earth, the tropical climate system, it is particularly relevant because one of the major determinants has been identified as clear sky OLR averaged over the entire Tropics. Due to the radiative importance of water vapor in higher altitudes and drier regions, the major (but not exclusive) focus of our attention is the tropical upper tropospheric water vapor in the subsiding regions. Furthermore, the nonlinearity of Outgoing Longwave Radiation (OLR) responses to humidity entails a more detailed statistical analysis than zonally averaged humidity. The main vehicle to conduct this statistical analysis is Probability Distribution Function (PDF) of water vapor mixing ratio. The general task of this study is to investigate water vapor distribution, maintenance and radiative impacts, as well evaluation of General Circulation Model (GCM) water vapor performances. Previous research on water vapor maintenance had lead to Large Scale Advection hypothesis, which serves as the basis for our study. Traditional observation has been lacking in both coverage and accuracy, Tiros Observational Vertical Sounder (TOVS) water vapor data, assisted by more recent CEPEX tropical sounding, are employed in the data analysis. The observational chapter is devoted to the examination of the morphology, regional, seasonal variation and vertical variation of PDF, possible climate impact as well as the effects of resolution are also examined. Our data analysis shows that TOVS water vapor PDF has a skewed appearance. A linear transform procedure is shown to be able to bring PDF from different layer to a close fit. The mean and deviation of water vapor mixing ratio display a positive correlation. These information are further used to evaluate GCM water vapor performance. Similar data analysis procedures are performed on GCM water vapor PDF's and results are compared with TOVS counterparts. GCM PDF shows similar morphological features, but its capability in capturing the seasonality needs improvement. Our theoretical effort concentrates on two aspects. The initial PDF problem and the geometry of humidity distribution field The moist tail of humidity PDF is found to be influenced by the mixing ratio inside convective region and the mass flux into the subsiding region. It is also demonstrated that the combination of subsidence drying and stretching could result in a power law of water vapor concentration field.

Zhang, Hui

2002-09-01

53

CO(2) DIAL measurements of water vapor.  

PubMed

CO(2) lidars have heretofore been used to measure water vapor concentrations primarily using the 10R(20) line at 10.247 microm, which has a strong overlap with a water vapor absorption line. This paper discusses the use of that line as well as other CO(2) laser lines for which the absorption coefficients are weaker. The literature on measurement of water vapor absorption coefficients using CO(2) lasers is reviewed, and the results from four laboratories are shown to be generally consistent with each other after they are normalized to the same partial pressure, temperature, and ethylene absorption coefficient for the 1P(14) CO(2) laser line; however, the agreement with the Air Force Geophysics Laboratory's HITRAN and FASCOD 2 spectral data tapes is not good either for the water vapor absorption lines or for the water vapor continuum. Demonstration measurements of atmospheric water vapor have been conducted using the Mobile Atmospheric Pollutant Mapping System, a dual CO(2) lidar system using heterodyne detection. Results are discussed for measurements using three sets of laser line pairs covering a wide range of water vapor partial pressures. PMID:20490006

Grant, W B; Margolis, J S; Brothers, A M; Tratt, D M

1987-08-01

54

Comparison of the water vapor and aerosol profiles  

NASA Astrophysics Data System (ADS)

Analysis of the contents of water vapor and aerosol in the atmosphere measured by means of different instruments was performed based on the results of the comprehensive aerosol experiment carried out at the Institute of Atmospheric optics in May 2012. The data obtained using remote (lidar) and contact (balloon) methods were used. They are capable of obtaining the vertical profiles of the measured parameters with high spatial resolution. Lidar measurements of the water vapor content in the boundary layer of the atmosphere by Raman method have shown very good agreement with the data of measurements by balloon. Simultaneous lidar measurements of backscattering and mixing ratio of water vapor in the atmosphere give significant positive correlation of the contents of water vapor and aerosol in the layers.

Penner, I. E.; Arshinov, M. Yu.; Balin, Yu. S.; Belan, B. D.; Voronin, B. A.; Kokhanenko, G. P.

2014-11-01

55

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

56

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

57

Optical monitor for water vapor concentration  

DOEpatents

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

58

Profiling of Atmospheric Water Vapor with MIR and LASE  

NASA Technical Reports Server (NTRS)

This paper presents the first and the only simultaneous measurements of water vapor by MIR (Millimeter-wave Imaging Radiometer) and LASE (Lidar Atmospheric Sounding Experiment) on board the same ER-2 aircraft. Water vapor is one of the most important constituents in the Earth's atmosphere, as its spatial and temporal variations affect a wide spectrum of meteorological phenomena ranging from the formation of clouds to the development of severe storms. Its concentration, as measured in terms of relative humidity, determines the extinction coefficient of atmospheric aerosol particles and therefore visibility. These considerations point to the need for effective and frequent measurements of the atmospheric water vapor. The MIR and LASE instruments provide measurements of water vapor profiles with two markedly different techniques. LASE can give water vapor profiles with excellent vertical resolution under clear condition, while MIR can retrieve water vapor profiles with a crude vertical resolution even under a moderate cloud cover. Additionally, millimeter-wave measurements are relatively simple and provide better spatial coverage.

Wang, J. R.; Racette, P.; Triesly, M. E.; Browell, E. V.; Ismail, S.; Chang, L. A.; Hildebrand, Peter H. (Technical Monitor)

2001-01-01

59

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

60

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

61

DISTRIBUTION OF WATER VAPOR IN MOLECULAR CLOUDS  

SciTech Connect

We report the results of a large-area study of water vapor along the Orion Molecular Cloud ridge, the purpose of which was to determine the depth-dependent distribution of gas-phase water in dense molecular clouds. We find that the water vapor measured toward 77 spatial positions along the face-on Orion ridge, excluding positions surrounding the outflow associated with BN/KL and IRc2, display integrated intensities that correlate strongly with known cloud surface tracers such as CN, C{sub 2}H, {sup 13}CO J = 5-4, and HCN, and less well with the volume tracer N{sub 2}H{sup +}. Moreover, at total column densities corresponding to A{sub V}< 15 mag, the ratio of H{sub 2}O to C{sup 18}O integrated intensities shows a clear rise approaching the cloud surface. We show that this behavior cannot be accounted for by either optical depth or excitation effects, but suggests that gas-phase water abundances fall at large A{sub V}. These results are important as they affect measures of the true water-vapor abundance in molecular clouds by highlighting the limitations of comparing measured water-vapor column densities with such traditional cloud tracers as {sup 13}CO or C{sup 18}O. These results also support cloud models that incorporate freeze out of molecules as a critical component in determining the depth-dependent abundance of water vapor.

Melnick, Gary J.; Tolls, Volker [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Snell, Ronald L. [Department of Astronomy, University of Massachusetts, Amherst, MA 01003 (United States); Bergin, Edwin A. [Department of Astronomy, University of Michigan, 825 Dennison Building, Ann Arbor, MI 48109 (United States); Hollenbach, David J. [SETI Institute, 515 North Whisman Road, Mountain View, CA 94043 (United States); Kaufman, Michael J. [Department of Physics and Astronomy, San Jose State University, One Washington Square, San Jose, CA 95192-0106 (United States); Li Di [Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States); Neufeld, David A., E-mail: gmelnick@cfa.harvard.edu, E-mail: vtolls@cfa.harvard.edu, E-mail: snell@astro.umass.edu, E-mail: ebergin@umich.edu, E-mail: dhollenbach@seti.org, E-mail: mkaufman@email.sjsu.edu, E-mail: dili@jpl.nasa.gov, E-mail: neufeld@pha.jhu.edu [Department of Physics and Astronomy, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218 (United States)

2011-01-20

62

Daytime Raman lidar measurements of water vapor during the ARM 1997 water vapor intensive observation period  

Microsoft Academic Search

Because of the importance of water vapor, the ARM program initiated a series of three intensive operating periods (IOPs) at its CART (Cloud And Radiation Testbed) site. The goal of these IOPs is to improve and validate the state-of-the-art capabilities in measuring water vapor. To date, two of the planned three IOPs have occurred: the first was in September of

D. D. Turner; J. E. M. Goldsmith

1998-01-01

63

Observed dependence of the water vapor and clear-sky greenhouse effect on sea surface temperature: Comparison with climate warming experiments  

Microsoft Academic Search

This study presents a comparison of the water vapor and clear-sky greenhouse effect dependence on sea surface temperature for climate variations of different types. Firstly, coincident satellite observations and meteorological analyses are used to examine seasonal and interannual variations and to evaluate the performance of a general circulation model. Then, this model is used to compare the results inferred from

Sandrine Bony; H. Le Treut; J. P. Duvel

1995-01-01

64

Observed dependence of the water vapor and clear-sky greenhouse effect on sea surface temperature: comparison with climate warming experiments  

Microsoft Academic Search

This study presents a comparison of the water vapor and clear-sky greenhouse effect dependence on sea surface temperature for climate variations of different types. Firstly, coincident satellite observations and meteorological analyses are used to examine seasonal and interannual variations and to evaluate the performance of a general circulation model. Then, this model is used to compare the results inferred from

Sandrine Bony; Jean-Philippe Duvel; Hervé Trent

1995-01-01

65

Advanced Atmospheric Water Vapor DIAL Detection System  

NASA Technical Reports Server (NTRS)

Measurement of atmospheric water vapor is very important for understanding the Earth's climate and water cycle. The remote sensing Differential Absorption Lidar (DIAL) technique is a powerful method to perform such measurement from aircraft and space. This thesis describes a new advanced detection system, which incorporates major improvements regarding sensitivity and size. These improvements include a low noise advanced avalanche photodiode detector, a custom analog circuit, a 14-bit digitizer, a microcontroller for on board averaging and finally a fast computer interface. This thesis describes the design and validation of this new water vapor DIAL detection system which was integrated onto a small Printed Circuit Board (PCB) with minimal weight and power consumption. Comparing its measurements to an existing DIAL system for aerosol and water vapor profiling validated the detection system.

Refaat, Tamer F.; Elsayed-Ali, Hani E.; DeYoung, Russell J. (Technical Monitor)

2000-01-01

66

Refraction of microwave signals by water vapor  

NASA Technical Reports Server (NTRS)

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

Goldfinger, A. D.

1980-01-01

67

Raman Lidar Water Vapor Measurements at the DOE SGP CART Site  

NASA Technical Reports Server (NTRS)

The NASA/GSFC Scanning Raman Lidar (SRL) was deployed to the Department of Energy's (DOE) Cloud and Radiation Testbed site in northern Oklahoma September - December, 2000 for two DOE sponsored field campaigns: 1) the Water Vapor Intensive Operations Experiment 2000 and 2) the Atmospheric Radiations Measurement First International Satellite Cloud Climatology Experiment Experiment (AFWEX). WvIOP2000 focussed on water vapor measurements in the lower troposphere while AFWEX focussed on upper tropospheric water vapor. For the first time ever, four water vapor lidars were operated simultaneously: one airborne and three ground-based systems. Intercomparisons of these measurements and others will be presented at the meeting.

Whiteman, David N.; Smith, David E. (Technical Monitor)

2001-01-01

68

Characterization of upper troposphere water vapor measurements during AFWEX using LASE  

Microsoft Academic Search

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

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

2002-01-01

69

Characterization of Upper-Troposphere Water Vapor Measurements during AFWEX Using LASE  

Microsoft Academic Search

Water vapor profiles from NASA's Lidar Atmospheric Sensing Experiment (LASE) system acquired during the ARM\\/FIRE Water Vapor Experiment (AFWEX) are used to characterize upper troposphere water vapor (UTWV) measured by ground -based Raman lidars, radiosondes, and in situ aircraft sensors. Initial comparisons showed the average Vaisala radiosonde measurements to be 5-15% drier than the average LASE, Raman lidar, and DC-8

Richard Ferrare; E. V. Browell; S. Ismail; S. A. Kooi; L. H. Brasseur; V. G. Brackett; M. B. Clayton; J. D. W. Barrick; G. S. Diskin; J. E. M. Goldsmith; B. M. Lesht; J. R. Podolske; G. W. Sachse; F. J. Schmidlin; David D. Turner; D. N. Whiteman; D. Tobin; L. M. Miloshevich; Henry E. Revercomb; B. B. Demoz; P. di Girolamo

2004-01-01

70

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

71

Scanning Raman lidar measurements of atmospheric water vapor and aerosols  

SciTech Connect

The principal objective of the Department of Energy`s (DOE) Atmospheric Radiation Measurement Program (ARM) is to develop a better understanding of the atmospheric radiative balance in order to improve the parameterization of radiative processes in general circulation models (GCMs) which are used to study climate change. Meeting this objective requires detailed measurements of both water vapor and aerosols since these atmospheric constituents affect the radiation balance directly, through scattering and absorption of solar and infrared radiation, and indirectly, through their roles in cloud formation and dissipation. Over the past several years, we have been investigating how the scanning Raman lidar developed at the NASA/Goddard Space Flight Center (GSFC) can provide the water vapor and aerosol measurements necessary for such modeling. The lidar system has provided frequent, high resolution profiles of atmospheric water vapor and aerosols in nighttime operations during two recent field experiments. The first experiment was ATMIS-11 (Atmospheric Moisture Intercomparison Study) conducted in July-August 1992, and the second was the Convection and Moisture Experiment (CAMEX) conducted during September-October 1993. We present a brief description of the lidar system and examples of the water vapor and aerosol measurements acquired during these experiments.

Ferrare, R.A.; Evans, K.D. [Hughes STX Corp., Lanham, MD (United States); Melfi, S.H.; Whiteman, D.N. [NASA/Goddard Space Flight Center, Greenbelt, MD (United States)

1995-04-01

72

Observe animated satellite images of water vapor  

NSDL National Science Digital Library

This animation shows Earth science students how jet streams drive the movement of water vapor in the atmosphere. The introduction explains how the infrared images were taken from a satellite positioned about 8 kilometers above the Earth's surface. Students are instructed to observe how the jet streams (indicated by dark areas) are juxtaposed against areas of dense water vapor (indicated by light areas). Movie controls allow students to repeat, pause, or step through the animation, which can give students more time to analyze the images. Copyright 2005 Eisenhower National Clearinghouse

Education, Terc. C.; Littell, Mcdougal

2003-01-01

73

Observations of water vapor ions at the lunar surface.  

NASA Technical Reports Server (NTRS)

The Apollo 14 Suprathermal Ion Detector Experiment observed a series of bursts of 48.6 eV water vapor ions at the lunar surface during a 14-hr period on Mar. 7, 1971. The maximum flux observed was 100 million ions per sq cm per sec per sr. These ions were also observed at Apollo 12, 183 km to the west. Evaluation of specific artificial sources including the Apollo missions and the Russian Lunokhod leads to the conclusion that the water vapor did not come from a man-made source. Natural sources exogenous to the moon such as comets and the solar wind are also found to be inadequate to explain the observed fluxes. Consequently, these water vapor ions appear to be of lunar origin.-

Freeman, J. W., Jr.; Hills, H. K.; Lindeman, R. A.; Vondrak, R. R.

1973-01-01

74

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

75

Aircraft experiments on microgravity pool boiling - Vapor-liquid behaviour and heat transfer characteristics in boiling of n-pentane, CFC113 and water  

Microsoft Academic Search

Boiling of n-pentane, CFC-113 and water under microgravity were studied, utilizing parabolic flight maneuvers with a Caravelle aircraft. The experimental apparatus was constructed so as to permit simultaneous video recording of the side view of vapor bubbles, generated on a Joule-heated, transparent indium-oxide film plated on a glass substrate, and the backside view through the substrate. The heat transfer to

Toshiharu Oka; Yoshiyuki Abe; Yasuhiko H. Mori; Akira Nagashima

1992-01-01

76

Compact water-vapor Raman lidar  

Microsoft Academic Search

Continuous monitoring of atmospheric water vapor mixing ratio profiles, especially within the planetary boundary layer is required for weather assessment, global circulation models and atmospheric studies. Although conventional lidar techniques based on Raman scattering or differential absorption are capable of such measurements, they are usually large, expensive systems with high power lasers which pose eye safety problems. This paper describes

Savyasachee L. Mathur; Coorg R. Prasad

1999-01-01

77

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

78

The effect of water vapor on the release of fission gas from the fuel elements of high temperature, gas-cooled reactors: A preliminary assessment of experiments HRB-17, HFR-B1, HFR-K6 and KORA  

SciTech Connect

The effect of water vapor on the release of fission gas from the fuel elements of high temperature, gas-cooled reactors has been measured in different laboratories under both irradiation and post irradiation conditions. The data from experiments HRB-17, HFR-B1, HFR-K6, and in the KORA facility are compared to assess their consistency and complimentarily. The experiments are consistent under comparable experimental conditions and reveal two general mechanisms involving exposed fuel kernels embedded in carbonaceous materials. One is manifest as a strong dependence of fission gas release on the partial pressure of water vapor below 1 kPa and the other, as a weak dependence above 1 kPa.

Myers, B.F.

1995-09-01

79

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

80

SCIAMACHY lunar occultation water vapor measurements: retrieval and validation results  

NASA Astrophysics Data System (ADS)

SCIAMACHY (SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY) lunar occultation measurements have been used to derive vertical profiles of stratospheric water vapor for the Southern Hemisphere in the near infrared (NIR) spectral range of 1350-1420 nm. The focus of this study is to present the retrieval methodology including the sensitivity studies and optimizations for the implementation of the radiative transfer model on SCIAMACHY lunar occultation measurements. The study also includes the validation of the data product with the collocated measurements from two satellite occultation instruments and two instruments measuring in limb geometry. The SCIAMACHY lunar occultation water vapor measurement comparisons with the ACE-FTS (Atmospheric Chemistry Experiment Fourier Transform Spectrometer) instrument have shown an agreement of 5% on the average that is well within the reported biases of ACE in the stratosphere. The comparisons with HALOE (Halogen Occultation Experiment) have also shown good results where the agreement between the instruments is within 5%. The validations of the lunar occultation water vapor measurements with MLS (Microwave Limb Sounder) instrument are exceptionally good, varying between 1.5 to around 4%. The validations with MIPAS (Michelson Interferometer for Passive Atmospheric Sounding) are in the range of 10%. A validated dataset of water vapor vertical distributions from SCIAMACHY lunar occultation measurements is expected to facilitate the understanding of physical and chemical processes in the southern mid-latitudes and the dynamical processes related to the polar vortex.

Azam, F.; Bramstedt, K.; Rozanov, A.; Weigel, K.; Bovensmann, H.; Stiller, G. P.; Burrows, J. P.

2012-10-01

81

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

82

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

83

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

84

New mobile Raman lidar for measurement of tropospheric water vapor  

Microsoft Academic Search

The content of water vapor in atmosphere is very little and the ratio of volume of moisture to air is about 0.1%–3%, but water\\u000a vapor is the most active molecule in atmosphere. There are many absorption bands in infrared (IR) wavelength for water vapor,\\u000a and water vapor is also an important factor in cloud formation and precipitation, therefore it takes

Chenbo Xie; Jun Zhou; Guming Yue; Fudi Qi; Aiyuan Fan

2007-01-01

85

Atmospheric Water Vapor Measurements' Comparison of Microwave Radiometry and Lidar  

Microsoft Academic Search

The NASAJGSFC Crustal Dynamics Project microwave water vapor radiometer 003) is evaluated in terms of measurements of the integrated precipitable water vapor content of a particular column of the troposphere. The measurements were taken during the Atmospheric Moisture Intercomparison Study (ATMIS) held at Wallops Island, Virginia, during April 1989. Various water vapor sensing instruments were used during ATMIS, including radiometers,

MARTIN N. ENGLAND; S. H. MELFI

1992-01-01

86

Atmospheric absorption of terahertz radiation and water vapor continuum effects  

E-print Network

Atmospheric absorption of terahertz radiation and water vapor continuum effects David M. Slocum a April 2013 Keywords: Water vapor Absorption Continuum Terahertz Spectroscopy a b s t r a c t The water vapor continuum absorption spectrum was investigated using Fourier Trans- form Spectroscopy

Massachusetts at Lowell, University of

87

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

88

Airborne Sunphotometer Measurements of Aerosol Optical Depth and Columnar Water Vapor During the Puerto Rico Dust Experiment, and Comparison with Land, Aircraft, and Satellite Measurements  

NASA Technical Reports Server (NTRS)

Analyses of aerosol optical depth (AOD) and columnar water vapor (CWV) measurements obtained with the six-channel NASA Ames Airborne Tracking Sunphotometer (AATS-6) mounted on a twin-engine aircraft during the summer 2000 Puerto Rico Dust Experiment are presented. In general, aerosol extinction values calculated from AATS-6 AOD measurements acquired during aircraft profiles up to 5 km ASL reproduce the vertical structure measured by coincident aircraft in-situ measurements of total aerosol number and surface area concentration. Calculations show that the spectral dependence of AOD was small (mean Angstrom wavelength exponents of approximately 0.20) within three atmospheric layers defined as the total column beneath the top of each aircraft profile, the region beneath the trade wind inversion, and the region within the Saharan Air Layer (SAL) above the trade inversion. This spectral behavior is consistent with attenuation of incoming solar radiation by large dust particles or by dust plus sea salt. Values of CWV calculated from profile measurements by AATS-6 at 941.9 nm and from aircraft in-situ measurements by a chilled mirror dewpoint hygrometer agree to within approximately 4% (0.13 g/sq cm). AATS-6 AOD values measured on the ground at Roosevelt Roads Naval Air Station and during low altitude aircraft runs over the adjacent Cabras Island aerosol/radiation ground site agree to within 0.004 to 0.030 with coincident data obtained with an AERONET Sun/sky Cimel radiometer located at Cabras Island. For the same observation times, AERONET retrievals of CWV exceed AATS-6 values by a mean of 0.74 g/sq cm (approximately 21 %) for the 2.9-3.9 g/sq cm measured by AATS-6. Comparison of AATS-6 aerosol extinction values obtained during four aircraft ascents over Cabras Island with corresponding values calculated from coincident aerosol backscatter measurements by a ground-based micro-pulse lidar (MPL-Net) located at Cabras yields a similar vertical structure above the trade inversion. Finally, AATS-6 AOD values measured during low altitude aircraft traverses over the ocean are compared with corresponding AOD values retrieved over water from upwelling radiance measurements by the MODIS, TOMS, and GOES-8 Imager satellite sensors, with mixed results. These exercises highlight the need for continued satellite sensor comparison/validation studies to improve satellite AOD retrieval algorithms, and the usefulness of airborne sunphotometer measurements in the validation process.

Livingston, John M.; Russell, Philip B.; Reid, Jeffrey; Redemann, Jens; Schmid, Beat; Allen, Duane A.; Torres, Omar; Levy, Robert C.; Remer, Lorraine A.; Holben, Brent N.; Hipskind, R. Stephen (Technical Monitor)

2002-01-01

89

Characterizing tropical Pacific water vapor and radiative biases in CMIP5 GCMs: Observation-based analyses and a snow and radiation interaction sensitivity experiment  

NASA Astrophysics Data System (ADS)

systematic biases in the moisture fields within the tropical Pacific trade wind regions are found in the Coupled Model Intercomparison Project (CMIP3/CMIP5) against profile and total column water vapor (TotWV) estimates from the Atmospheric Infrared Sounder and TotWV from the Special Sensor Microwave/Imager. Positive moisture biases occur in conjunction with significant biases of eastward low-level moisture convergence north of the South Pacific Convergence Zone and south of the Intertropical Convergence Zone—the V-shaped regions. The excessive moisture there is associated with overestimates of reflected upward shortwave (RSUT), underestimates of outgoing longwave radiation (RLUT) at the top of atmosphere (TOA), and underestimates of downward shortwave flux at the surface (RSDS) compared to Clouds and the Earth's Energy System, Energy Balance and Filled data. We characterize the impacts of falling snow and its radiation interaction, which are not included in most CMIP5 models, on the moisture fields using the National Center for Atmospheric Research-coupled global climate model (GCM). A number of differences in the model simulation without snow-radiation interactions are consistent with biases in the CMIP5 simulations. These include effective low-level eastward/southeastward wind and surface wind stress anomalies, and an increase in TotWV, vertical profile of moisture, and cloud amounts in the V-shaped region. The anomalous water vapor and cloud amount might be associated with the model increase of RSUT and decrease of RLUT at TOA and decreased RSDS in clear and all sky in these regions. These findings hint at the importance of water vapor-radiation interactions in the CMIPS/CMIP5 model simulations that exclude the radiative effect of snow.

Li, J.-L. F.; Lee, W.-L.; Waliser, D. E.; Stachnik, Justin P.; Fetzer, Eric; Wong, Sun; Yue, Qing

2014-10-01

90

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

91

Water vapor differential absorption lidar development and evaluation.  

PubMed

A ground-based differential absorption lidar (DIAL) system is described which has been developed for vertical range-resolved measurements of water vapor. The laser transmitter consists of a ruby-pumped dye laser, which is operated on a water vapor absorption line at 724.372 nm. Part of the ruby laser output is transmitted simultaneously with the dye laser output to determine atmospheric scattering and attenuation characteristics. The dye and ruby laser backscattered light is collected by a 0.5-m diam telescope, optically separated in the receiver package, and independently detected using photomultiplier tubes. Measurements of vertical water vapor concentration profiles using the DIAL system at night are discussed, and comparisons are made between the water vapor DIAL measurements and data obtained from locally launched rawinsondes. Agreement between these measurements was found to be within the uncertainty of the rawinsonde data to an altitude of 3 km. Theoretical simulations of this measurement were found to give reasonably accurate predictions of the random error of the DIAL measurements. Confidence in these calculations will permit the design of aircraft and Shuttle DIAL systems and experiments using simulation results as the basis for defining lidar system performance requirements. PMID:20216627

Browell, E V; Wilkerson, T D; McIlrath, T J

1979-10-15

92

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

93

Improved cell for water-vapor electrolysis  

NASA Technical Reports Server (NTRS)

Continuous-flow electrolytic cells decompose water vapor in steam and room air into hydrogen and oxygen. Sintered iridium oxide catalytic anode coating yields dissociation rates hundredfold greater than those obtained using platinum black. Cell consists of two mirror-image cells, with dual cathode sandwiched between two anodes. Gas traverses serpentine channels within cell and is dissociated at anode. Oxygen mingles with gas stream, while hydrogen migrates through porous matrix and is liberated as gas at cathode.

Aylward, J. R.

1981-01-01

94

Exchange of tritium between water and vapor. Final report  

SciTech Connect

Isotopic exchange was measured by filling beakers with waters of different isotopic compositions and allowing them to equilbrate via the vapor phase in plexiglas boxes. Tritium analyses were performed prior to and after the experiment. The waters ranged in {delta}D from -105 to +27 per mil, and from -13.0 to +9 per mil in {delta}{sup 18}O; tritium contents ranged from <10 pCi/l to nearly 320,000 pCi/l. Results are reported for three- and two-beaker systems; a bubble exchange experiment was also conducted. 3 tabs.

Ingraham, N.L.

1993-06-01

95

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

96

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

97

Atmospheric absorption of terahertz radiation and water vapor continuum effects  

E-print Network

Atmospheric absorption of terahertz radiation and water vapor continuum effects David M. Slocum a vapor Absorption Continuum Terahertz Spectroscopy a b s t r a c t The water vapor continuum absorption. The absorption coefficient as a function of frequency was determined and compared with theoretical predictions

Massachusetts at Lowell, University of

98

Transient water vapor at Europa's south pole.  

PubMed

In November and December 2012, the Hubble Space Telescope (HST) imaged Europa's ultraviolet emissions in the search for vapor plume activity. We report statistically significant coincident surpluses of hydrogen Lyman-? and oxygen OI 130.4-nanometer emissions above the southern hemisphere in December 2012. These emissions were persistently found in the same area over the 7 hours of the observation, suggesting atmospheric inhomogeneity; they are consistent with two 200-km-high plumes of water vapor with line-of-sight column densities of about 10(20) per square meter. Nondetection in November 2012 and in previous HST images from 1999 suggests varying plume activity that might depend on changing surface stresses based on Europa's orbital phases. The plume was present when Europa was near apocenter and was not detected close to its pericenter, in agreement with tidal modeling predictions. PMID:24336567

Roth, Lorenz; Saur, Joachim; Retherford, Kurt D; Strobel, Darrell F; Feldman, Paul D; McGrath, Melissa A; Nimmo, Francis

2014-01-10

99

Effects of vertical distribution of water vapor and temperature on total column water vapor retrieval error  

NASA Technical Reports Server (NTRS)

Results are presented of a test of the physically based total column water vapor retrieval algorithm of Wentz (1992) for sensitivity to realistic vertical distributions of temperature and water vapor. The ECMWF monthly averaged temperature and humidity fields are used to simulate the spatial pattern of systematic retrieval error of total column water vapor due to this sensitivity. The estimated systematic error is within 0.1 g/sq cm over about 70 percent of the global ocean area; systematic errors greater than 0.3 g/sq cm are expected to exist only over a few well-defined regions, about 3 percent of the global oceans, assuming that the global mean value is unbiased.

Sun, Jielun

1993-01-01

100

Daytime Raman lidar measurements of water vapor during the ARM 1997 water vapor intensive observation period  

SciTech Connect

Because of the importance of water vapor, the ARM program initiated a series of three intensive operating periods (IOPs) at its CART (Cloud And Radiation Testbed) site. The goal of these IOPs is to improve and validate the state-of-the-art capabilities in measuring water vapor. To date, two of the planned three IOPs have occurred: the first was in September of 1996, with an emphasis on the lowest kilometer, while the second was conducted from September--October 1997 with a focus on both the upper troposphere and lowest kilometer. These IOPs provided an excellent opportunity to compare measurements from other systems with those made by the CART Raman lidar. This paper addresses primarily the daytime water vapor measurements made by the lidar system during the second of these IOPs.

Turner, D.D. [Pacific Northwest National Lab., Richland, WA (United States); Goldsmith, J.E.M. [Sandia National Labs., Livermore, CA (United States)

1998-04-01

101

Understanding the Sahelian water budget through the isotopic composition of water vapor and precipitation  

NASA Astrophysics Data System (ADS)

The goal of this paper is to investigate the added value of water isotopic measurements to estimate the relative influence of large-scale dynamics, convection, and land surface recycling on the Sahelian water budget. To this aim, we use isotope data in the lower tropospheric water vapor measured by the SCIAMACHY and TES satellite instruments and in situ precipitation data from the Global Network for Isotopes in Precipitation and collected during the African Monsoon Multidisciplinary Analysis field campaign, together with water-tagging experiments with the Laboratoire de Météorologie Dynamique general circulation model (LMDZ) fitted with isotopes. We show that some isotopic biases in LMDZ reveal the misrepresentation of dehydrating processes that would be undetected without isotopic measurements. In dry regions, the vapor isotopic composition is primarily controlled by the intensity of the air dehydration. In addition, it may also keep some memory of dehydration pathways that is erased in the humidity distribution, namely the relative contribution of dehydration in the tropical upper troposphere versus midlatitudes. In wet regions, vapor and rain isotope compositions are primarily controlled by changes in convection, through rain reevaporation and through the progressive depletion of the vapor by convective mixing along air mass trajectories. Gradients in vapor isotope composition along air mass trajectories may help estimate continental recycling intensity, provided that we could quantify the effect of convection on the isotopic composition of water vapor.

Risi, Camille; Bony, Sandrine; Vimeux, FrançOise; Frankenberg, Christian; Noone, David; Worden, John

2010-12-01

102

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

103

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

104

Climate monitoring using GPS and MODIS water vapor  

NASA Astrophysics Data System (ADS)

Water vapor is an important constituent of the atmosphere and show high degree of spatial and temporal variability. Role of water vapor in the radiative balance and hydrological cycle is one of the least understood subjects. Water vapor is a principal component that interacts with the incoming and outgoing solar radiation and controls the thermodynamics and energy balance of the atmosphere. Water vapor concentrations vary by orders of magnitudes depending upon topography, wind and other local and regional climatic conditions. A ground based dual frequency Global Positioning System (GPS) have been used to estimate the integrated precipitable water vapor (IPWV) at three sites (Kanpur, Hyderabad and Bangalore) in the Indian subcontinent. In general, Kanpur site which is located in the central part of the Indo-Gangetic (IG) basin is representative of the IG basin (northern India) and Hyderabad-Bangalore site is representative of climatic conditions of the southern parts of India. GPS IPWV shows a strong sensitivity to high level of water vapor in the atmosphere during arrival of monsoon clouds and compares well with ground measurement of rainfall. Moderate Resolution Imaging Spectroradiometer (MODIS) Terra derived water vapor has been used to study daily and seasonal variability of water vapor along with ground based GPS IPWV. A good correlation has been found between satellite (MODIS) derived daily water vapor and ground based GPS IPWV. Both GPS and MODIS water vapor show high degree of variability of water vapor concentration and are closely approximated by the lognormal distribution statistically. A seasonal decomposition of MODIS and GPS water vapor show both uni-modal and bimodal (during monsoon season) character of water vapor depending upon season. During the summer season, MODIS water vapor show relatively a higher offset compared to GPS IPWV and a correction factor can be applied to MODIS water vapor data. GPS IPWV shows a conspicuous increase with arrival of major dust storms over Kanpur indicating association of water vapor with dust storms over the IG basin. Our results indicate that a near real time GPS IPWV (with better temporal sampling) and satellite derived water vapor such as MODIS Terra (with good spatial coverage) can be used to improve local weather forecast and assimilated into global climate models.

Prasad, A. K.; Nanda, D. S.; Singh, S.; Singh, R. P.

2006-12-01

105

Water vapor measurements by Raman lidar during the ARM 1997 Water Vapor Intensive Observation Period  

Microsoft Academic Search

The Department of Energy's Atmospheric Radiation Measurement (ARM) program initiated a series of three intensive operating periods (IOPs) at its Cloud and Radiation Testbed (CART) site in northern Oklahoma. The goal of these IOPs is to improve and validate the state-of-the-art capabilities in measuring water vapor. To date, two of the planned three IOPs have occurred: the first was in

D. D. Turner; D. N. Whiteman; K. D. Evans; S. H. Melfi; J. E. M. Goldsmith; G. K. Schwemmer

1998-01-01

106

Airborne DIAL and ground-based Raman lidar measurements of water vapor over the Southern Great Plains  

Microsoft Academic Search

Measurements of water vapor profiles over the Southern Great Plains acquired by two different lidars are presented. NASA's airborne DIAL Lidar Atmospheric Sensing Experiment (LASE) system measured water vapor, aerosol, and cloud profiles during the ARM\\/FIRE Water Vapor Experiment (AFWEX) in November-December 2000 and during the International H2O Project (IHOP) in May-June 2002. LASE measurements acquired during AFWEX are used

Richard A. Ferrare; Edward V. Browell; Syed Ismail; Susan Kooi; Vince G. Brackett; Marian Clayton; Anthony Notari; Carolyn F. Butler; John Barrick; Glenn Diskin; Barry Lesht; Frank J. Schmidlin; Dave Turner; David Whiteman; Larry Miloshevich

2003-01-01

107

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

108

First lidar measurements of water vapor and aerosols from a high-altitude aircraft  

NASA Technical Reports Server (NTRS)

Water vapor plays an important role in many atmospheric processes related to radiation, climate change, atmospheric dynamics, meteorology, the global hydrologic cycle, and atmospheric chemistry, and yet our knowledge of the global distribution of water vapor is very limited. The differential absorption lidar (DIAL) technique has the potential of providing needed high resolution water vapor measurements from aircraft and from space, and the Lidar Atmospheric Sensing Experiment (LASE) is a key step in the development of this capability. The LASE instrument is the first fully engineered, autonomous DIAL system, and it is designed to operate from a high-altitude aircraft (ER-2) and to make water vapor and aerosol profile measurements across the troposphere. The LASE system was flown from the NASA Wallops Flight Facility in a series of engineering flights during September 1994. This paper discusses the characteristics of the LASE system and presents the first LASE measurements of water vapor and aerosol profiles.

Browell, Edward V.; Ismail, Syed

1995-01-01

109

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

110

Performance Modeling of an Airborne Raman Water-Vapor Lidar  

Microsoft Academic Search

We have developed a sophisticated Raman lidar numerical model to simulate the performance of two ground-based Raman water-vapor lidar systems. After verifying the model using these ground-based measurements, we then used the model to simulate the water-vapor measurement capability of an airborne Raman lidar under both daytime and nighttime conditions for a wide range of water-vapor conditions. The results indicate

David N. Whiteman; Geary Schwemmer; Timothy Berkoff; Henry Plotkin; Luis Ramos-Izquierdo; Gelsomina Pappalardo

2001-01-01

111

Raman lidar water vapor measurements performed at CNR-IMAA  

Microsoft Academic Search

A Raman lidar system for water vapor measurements is operational at Istituto di Metodologie per l'Analisi Ambientale (IMAA),in Tito Scalo, Potenza, (Southern Italy, 40°36'N, 15°44'E, 760 m above sea level) since July 2002. The Raman technique is widely employed for tropospheric water vapor measurements with high vertical and temporal resolution. In principle, Raman lidar measurement of water vapor can be

C. Cornacchia; A. Amodeo; G. D'Amico; F. Madonna; L. Mona; G. Pappalardo

2005-01-01

112

Water vapor measurements by Raman lidar during the ARM 1997 water vapor intensive observation period  

SciTech Connect

Water vapor is the most important greenhouse gas in the atmosphere, as it is the most active infrared absorber and emitter of radiation, and it also plays an important role in energy transport and cloud formation. Accurate, high resolution measurements of this variable are critical in order to improve the understanding of these processes and thus their ability to model them. Because of the importance of water vapor, the Department of Energy`s Atmospheric Radiation Measurement (ARM) program initiated a series of three intensive operating periods (IOPs) at its Cloud and Radiation Testbed (CART) site in northern Oklahoma. The goal of these IOPs is to improve and validate the state-of-the-art capabilities in measuring water vapor. To date, two of the planned three IOPs have occurred: the first was in September of 1996, with an emphasis on the lowest kilometer, while the second was conducted from September--October 1997 with a focus on both the upper troposphere and lowest kilometer. The ARM CART site is the home of several different water vapor measurement systems. These systems include a Raman lidar, a microwave radiometer, a radiosonde launch site, and an instrumented tower. During these IOPs, additional instrumentation was brought to the site to augment the normal measurements in the attempt to characterize the CART instruments and to address the need to improve water vapor measurement capabilities. Some of the instruments brought to the CART site include a scanning Raman lidar system from NASA/GSFC, additional microwave radiometers from NOAA/ETL, a chilled mirror that was flown on a tethersonde and kite system, and dewpoint hygrometer instruments flow on the North Dakota Citation. This paper will focus on the Raman lidar intercomparisons from the second IOP.

Turner, D.D. [Pacific Northwest National Lab., Richland, WA (United States); Whiteman, D.N.; Schwemmer, G.K. [National Aeronautics and Space Administration, Greenbelt, MD (United States). Goddard Space Flight Center; Evans, K.D. [Univ. of Maryland, Baltimore, MD (United States)]|[National Aeronautics and Space Administration, Greenbelt, MD (United States). Goddard Space Flight Center; Melfi, S.H. [Univ. of Maryland, Baltimore, MD (United States); Goldsmith, J.E. [Sandia National Labs., Livermore, CA (United States)

1998-04-01

113

An approach to evaluate the absolute accuracy of WVR water vapor measurements inferred from multiple water vapor techniques  

NASA Astrophysics Data System (ADS)

This paper uses three different types of water vapor observation instruments, radiosonde, AERONET sunphotometer and GPS, to infer the regression coefficients of one WVR (model: WVR-1100) in Hong Kong - a coastal city with high humidity. The regression using the three types of reference water vapor data is performed on a monthly basis for 6 months from January to June 2012. In order to evaluate the WVR regression accuracies, a water vapor-assisted (WV-assisted) GPS Precise Point Positioning (PPP) method is proposed. The inferred water vapor data are directly injected into PPP computation to correct the water vapor wet tropospheric delay in GPS signals. In principle, water vapor of better accuracy will produce GPS PPP solutions of higher accuracy. Our analysis results show that the radiosonde, AERONET and GPS data all can be used to regress WVR and produce accurate WVR water vapor if the regressed instruments have good data quality. We find that the WVR water vapor inferred from GPS water vapor regression has the most reliable regression results. The vertical component of PPP solutions is very stable, with consistent biases (bias varying by 0.38 cm) and standard deviations (bias variation by 0.59 cm) over a 6-month period in 2012. When sufficient AEROENT water vapor data are available for WVR regression, the WVR water vapor accuracy will become compatible with that inferred from GPS water vapor regression. However AERONET water vapor measurements are seriously affected by weather condition and can be obtained only in sunny and clear conditions. Compared with the bias variation of 0.38 cm using GPS water vapor to regress WVR, the WVR water vapor data regressed by radiosonde result in a bias variation of 3.95 cm in the PPP vertical component during the 6-month period. All of the regressed WVR contain a bias, which possibly results from the fact that the WVR, GPS, AERONET and radiosonde stations are all horizontally and vertically separated. Overall, the WVR water vapor data inferred from GPS water vapor regression are regarded to be most reliable and it is the most suitable data source for WVR regression.

Liu, Zhizhao; Li, Min; Zhong, Weikun; Wong, Man Sing

2013-12-01

114

The relationship between clear sky water vapor and SST anomalies  

NASA Technical Reports Server (NTRS)

The relationship between clear sky water vapor anomalies and the SST anomalies (SSTAs) was investigated with the purpose of providing data for evaluating the clear sky greenhouse effect predicted in many global warming scenarios, by statistically analyzing anomaly data sets of SST and the water vapor anomaly data (obtained by subtracting the mean value of the six years of data for a given month from the observed values). Results show that clear sky water vapor anomalies increase in association with increases in SSTAs. The clear sky water vapor anomalies high in the troposphere were also found to increase with increasing SSTA.

Peterson, Thomas C.; Vonder Haar, Thomas H.

1992-01-01

115

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

116

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

117

Holographic studies of the vapor explosion of vaporizing water-in-fuel emulsion droplets  

NASA Technical Reports Server (NTRS)

Holographic studies were performed which examined the fragmentation process during vapor explosion of a water-in-fuel (hexadecane/water) emulsion droplet. Holograms were taken at 700 to 1000 microseconds after the vapor explosion. Photographs of the reconstructed holograms reveal a wide range of fragment droplet sizes created during the explosion process. Fragment droplet diameters range from below 10 microns to over 100 microns. It is estimated that between ten thousand and a million fragment droplets can result from this extremely violent vapor explosion process. This enhanced atomization is thus expected to have a pronounced effect on vaporization processes which are present during combustion of emulsified fuels.

Sheffield, S. A.; Hess, C. F.; Trolinger, J. D.

1982-01-01

118

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

119

Characterization and mitigation of water vapor effects in the measurement of ozone by chemiluminescence with nitric oxide  

NASA Astrophysics Data System (ADS)

Laboratory experiments were conducted to investigate the effects of water vapor on the reaction of nitric oxide with ozone in a gas-phase chemiluminescence instrument used for fast response and high sensitivity detection of atmospheric ozone. Water vapor was introduced into a constant level ozone standard and both ozone and water vapor signals were recorded at 10 Hz. The presence of water vapor was found to reduce, i.e. quench, the ozone signal. A dimensionless correction factor was determined to be 4.15 ± 0.14 × 10-3, which corresponds to a 4.15% increase in the corrected ozone signal per 10 mmol mol-1 of co-sampled water vapor. An ozone-inert water vapor permeable membrane (a Nafion dryer with a counterflow of dry air from a compressed gas cylinder) was installed in the sampling line and was shown to remove the bulk of the water vapor in the sample air. At water vapor mole fractions above 25 mmol mol-1, the Nafion dryer removed over 75% of the water vapor in the sample. This reduced the required ozone signal correction from over 11% to less than 2.5%. The Nafion dryer was highly effective at reducing the fast fluctuations of the water vapor signal (more than 97%) while leaving the ozone signal unaffected, which is a crucial improvement for minimizing the quenching interference of water vapor fluxes and required density correction in the determination of ozone fluxes by the eddy covariance technique.

Boylan, P.; Helmig, D.; Park, J.-H.

2014-05-01

120

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

121

Water recovery by catalytic treatment of urine vapor  

NASA Technical Reports Server (NTRS)

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

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

1980-01-01

122

VAPOR + LIQUID EQUILIBRIUM OF WATER, CARBON DIOXIDE, AND THE BINARY SYSTEM WATER + CARBON DIOXIDE FROM  

E-print Network

) were used to describe the properties of the pure substances. The vapor pressures of water and carbonVAPOR + LIQUID EQUILIBRIUM OF WATER, CARBON DIOXIDE, AND THE BINARY SYSTEM WATER + CARBON DIOXIDE the vapor-liquid equilibrium of water (between 323 and 573 K), carbon dioxide (between 230 and 290 K

123

Putting Water Vapor Feedback Back On It's Feet (Invited)  

NASA Astrophysics Data System (ADS)

Authors: Stephens, Graeme L., Ming Cai, Paul Stackhouse, and Tristan L'Ecuyer It has been understood for some time that changes to the strength of the greenhouse effect are fundamental to our understanding of global warming. The role of the positive water vapor feedback that occurs through the connections between temperature, water vapor, and emission of infrared radiation has also been equally understood for some time. Recently, debate about the magnitude of this feedback has mostly focused on the role of changes to tiny amounts of water vapor high in the troposphere on atmospheric emission and it's now perceived by many that the water vapor climate feedback is entirely defined by changes to upper tropospheric water vapor through its influence on the outgoing longwave radiation. This talk will demonstrate this isn't entirely correct and will demonstrate the fundamental importance of the downward longwave radiation to the surfaces as the driving force of the water vapor feedback. Our current state of knowledge of the DLR will be reviewed by comparing various data sources that have been used to create global composites of this quantity, including new data from the A-Train. The role of DLR in climate change through the water vapor feedback and it's control of global precipitation is also discussed highlighting it's relation to low level water vapor.

Stephens, G. L.; Cai, M.; Stackhouse, P. W.; L'Ecuyer, T. S.

2009-12-01

124

Water vapor measurements by lidar: Raman and DIAL campaigns  

Microsoft Academic Search

Ground-based water vapor measurements by lidar have been performed in Potenza, Southern Italy, by the application of the Raman and the DIAL techniques. Raman measurements have been accomplished through the simultaneous detection of the backscattered radiation in the vibrational Raman bands of water vapor and molecular nitrogen as stimulated by a 355 nm beam, while DIAL measurements at 720 nm

Paolo Di Girolamo

2000-01-01

125

Semiconductor laser transmitter for water vapor lidar on Mars  

Microsoft Academic Search

This dissertation investigates the feasibility of a novel, low power miniature lidar intended to measure the vertical distribution of atmospheric water vapor on Mars. This instrument could provide valuable information crucial to understanding the past and present climate of Mars. The emphasis is to develop a compact, efficient, all-semiconductor laser transmitter and demonstrate its ability to measure water vapor at

Greggory William Switzer

1999-01-01

126

Water Vapor Measurements from HALOE (1992-1997)  

NSDL National Science Digital Library

An animated graph showing HALOE measurements of the water vapor amounts in the upper stratosphere, illustrating that it takes about 5 years for CFCs to reach the upper atmosphere. Tropical water vapor changes slowly with seasonal cycles. These changes, shown here as thick bands, were found to slowly ascend. These measurements tell us how fast the CFCs and other pollutants rise into the stratosphere.

Mitchell, Horace; Schoeberl, Mark

1999-04-09

127

EXAMINING THE SPECTROSCOPY OF WATER VAPOR IN THE ATMOSPHERE  

E-print Network

EXAMINING THE SPECTROSCOPY OF WATER VAPOR IN THE ATMOSPHERE USING A VERTICAL CAVITY SURFACE EMITTING LASER Elise Pusateri, Professor Mark Zondlo, Minghui Diao #12;ATMOSPHERIC WATER VAPOR Greenhouse data acquisition for kHz sampling of atmosphere #12;ACKNOWLEDGEMENTS Professor Zondlo Minghui Diao

Petta, Jason

128

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

129

Water Vapor Corrections to Mid-Infrared Photometry  

NASA Astrophysics Data System (ADS)

We explore water vapor corrections for the San Pedro Mártir mid-infrared photometric system CID. Atmosphere opacity is measured by a 210 GHz radiometer. By using the results of the ATM code, we propose a linear relationship between 210 GHz opacity and water vapor content. This relation allows us to determine the water vapor content in the atmosphere from opacity measurements at the radiometer frequency. We also obtain a relation between water vapor content and mid-infrared opacity by using the MODTRAN 3 atmospheric model. Thus, through the water vapor we obtain a relation that connects millimeter opacity to mid-infrared opacity under clear sky conditions. We tested this relation with measurements made at San Pedro Mártir of these two opacities.

Hiriart, D.; Salas, L.

2007-04-01

130

A NEW PERSPECTIVE ON WATER FLOW FROM SOIL TO SEED: THE ROLE OF VAPOR  

Technology Transfer Automated Retrieval System (TEKTRAN)

It is commonly assumed that flow of liquid water from soil to seed is the major source of water for imbibition. Four different laboratory experiments provide evidence to the contrary, that is, that vapor flow is rapid and can account for at least 85% of imbibed water. 1) Seed separated from soil b...

131

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

132

NASA LASE water vapor differential absorption lidar measurements and performance evaluation  

Microsoft Academic Search

The Lidar Atmospheric Sensing Experiment (LASE) is a highly engineered and autonomous Differential Absorption Lidar (DIAL) system developed at NASA Langley Research Center (LaRC) to measure high-resolution water vapor and aerosol profiles in the troposphere. LASE is being developed as a precursor to the deployment of a spaceborne DIAL system for global measurement of high-resolution water vapor profiles. The LASE

S. Ismail; E. V. Browell

1995-01-01

133

The water vapor plumes of Enceladus  

NASA Astrophysics Data System (ADS)

The Cassini E3, E5, and E7 encounters with Enceladus probed the south polar plumes, where the Ion and Neutral Mass Spectrometer (INMS) measured neutral H2O molecular densities up to ˜109 cm-3. We have constructed a physical model for the expected water density in the plumes, based on supersonic radial outflow from one or more of the surface vents. We apply this model to possible surface sources of water vapor associated with the multiple jets observed in the visible dust plumes. Our model predictions fit well with the INMS measurements of neutral H2O density along the E3, E5, and E7 trajectories. The fit is optimized by values of outflow velocity in the range ˜550-750 m/s and values of total source rate in the range ˜1.5 - 3.5 × 1028 H2O molecules/s. The model can be extended to incorporate the jet features within the plume observed during the E7 encounter.

Dong, Y.; Hill, T. W.; Teolis, B. D.; Magee, B. A.; Waite, J. H.

2011-10-01

134

Water Vapor in Carbon-rich AGB Stars from the Vaporization of Icy Orbiting Bodies  

E-print Network

We argue that the presence of water vapor in the circumstellar outflow of a carbon-rich AGB star is potentially a distinctive signature of extra-solar cometary systems. Detailed models show that at suitable distances from the star, water ice can survive well into the carbon-rich AGB phase; water vapor abundances as large as 10^-6 could result from the vaporization of a collection of orbiting icy bodies with a total mass comparable to what might have been originally present in the solar system's Kuiper Belt. In particular, the recently-reported detection by the Submillimeter Wave Astronomy Satellite of water vapor in the circumstellar outflow of IRC+10216 can be explained if ~10 Earth masses of ice is present at a distance ~300 AU from that carbon-rich star. Future observations with the Herschel Space Observatory (HSO, formerly known as FIRST) will facilitate sensitive multi-transition observations of water, yielding line ratios that can establish the radial distribution of water vapor in IRC+10216. The greater sensitivity of HSO will also allow searches for water vapor to be carried out in a much larger sample of carbon-rich AGB stars.

K. E. Saavik Ford; David A. Neufeld

2001-07-12

135

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 water vapor (UTWV) measured by ground-based Raman lidars, radiosondes, and in situ aircraft sensors over the Department of Energy Atmospheric Radiation Measurement (ARM) Southern Great Plains (SGP) site in northern Oklahoma. LASE was deployed from the NASA DC-8 aircraft and measured water vapor over the ARM SGP Central Facility (CF) site during seven flights between November 27 and December 10, 2000. Initially, the DOE ARM SGP Cloud and Radiation Testbed (CART) Raman lidar (CARL) UTWV profiles were about 5-7% wetter than LASE in the upper troposphere, and the Vaisala RS80-H radiosonde profiles were about 10% drier than LASE between 8-12 km. Scaling the Vaisala water vapor profiles to match the precipitable water vapor (PWV) measured by the ARM SGP microwave radiometer (MWR) did not change these results significantly. By accounting for an overlap correction of the CARL water vapor profiles and by employing schemes designed to correct the Vaisala RS80-H calibration method and account for the time response of the Vaisala RS80H water vapor sensor, the average differences between the CARL and Vaisala radiosonde upper troposphere water vapor profiles are reduced to about 5%, which is within the ARM goal of mean differences of less than 10%. The LASE and DC-8 in situ Diode Laser Hygrometer (DLH) UTWV measurements generally agreed to within about 3 to 4%. The DC-8 in situ frost point cryogenic hygrometer and Snow White chilled mirror measurements were drier than the LASE, Raman lidars, and corrected Vaisala RS80H measurements by about 10-25% and 10-15%, respectively. Sippican (formerly VIZ manufacturing) carbon hygristor radiosondes exhibited large variabilities and poor agreement with the other measurements. PWV derived from the LASE profiles agreed to within about 3% on average with PWV derived from the ARM SGP microwave radiometer. The agreement between the LASE and MWR PWV and the LASE and CARL UTWV measurements supports the hypotheses that MWR measurements of the 22 GHz water vapor line can accurately constrain the total water vapor amount and that the CART Raman lidar, when calibrated using the MWR PWV, can provide an accurate, stable reference for characterizing upper troposphere water vapor.

Ferrare, Richard; Browell, E. V.; Ismail, S.; Barrick, J. D. W.; Diskin, G. S.; Sachse, G. W.; Kooi, S. A.; Brasseur, L. H.; Brackett, V. G.; Clayton, M. B.; Goldsmith, John E M.; Lesht, B. M.; Podolske, J. R.; Schmidlin, F. J.; Turner, David D.; Whiteman, D. N.; Demoz, B. B.; Tobin, D. C.; Revercomb, Henry E.; Miloshevich, Larry M.; di Girolamo, P.

2004-12-01

136

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

137

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

138

Water vapor and methane in the upper stratosphere - An examination of some of the Nimbus 7 measurements  

NASA Technical Reports Server (NTRS)

The zonal mean volume mixing ratios of water vapor and methane from January to May, 1979, derived from the Nimbus-7 limb IR monitor of the stratosphere and from stratosphere and mesosphere sounder experiments are investigated. The water vapor mixing ratio of air that enters the stratosphere from the troposphere and the yield of water vapor from photochemical oxidation of methane in the stratosphere are examined. The water vapor yield averaged between 1.5 and 2.0, although variability with time and level was relatively large. It is suggested that water vapor yield increases with height in the 16- to 3-mbar range. The average water vapor mixing ratio fo air entering the stratosphere during the study period was about 3.25 X 10 to the -6th.

Hansen, Anthony R.; Robinson, G. D.

1989-01-01

139

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

140

Contrasting Effects of Central Pacific and Eastern Pacific El Nino on Stratospheric Water Vapor  

NASA Technical Reports Server (NTRS)

Targeted experiments with a comprehensive chemistry-climate model are used to demonstrate that seasonality and the location of the peak warming of sea surface temperatures dictate the response of stratospheric water vapor to El Nino. In spring, El Nino events in which sea surface temperature anomalies peak in the eastern Pacific lead to a warming at the tropopause above the warm pool region, and subsequently to more stratospheric water vapor (consistent with previous work). However, in fall and in early winter, and also during El Nino events in which the sea surface temperature anomaly is found mainly in the central Pacific, the response is qualitatively different: temperature changes in the warm pool region are nonuniform and less water vapor enters the stratosphere. The difference in water vapor in the lower stratosphere between the two variants of El Nino approaches 0.3 ppmv, while the difference between the winter and spring responses exceeds 0.5 ppmv.

Garfinkel, Chaim I.; Hurwitz, Margaret M.; Oman, Luke D.; Waugh, Darryn W.

2013-01-01

141

Multiple-wavelength Raman lidar measurements of atmospheric water vapor  

SciTech Connect

Height profiles of atmospheric water vapor obtained using a multiple-wavelength Raman lidar are examined. The water vapor profiles exhibit vertical structure with scales on the order of the resolution of the lidar (75 m). To determine whether such structure is atmospheric in origin, measurements obtained simultaneously in a common volume at two independent wavelengths were compared. Correlation of the gradients of the water vapor profiles obtained from these two wavelengths yielded an average correlation factor of 0.88. It was also observed that for the given meteorological conditions, the vertical structure decorrelated with a time constant of approximately three hours. 7 refs., 4 figs., 1 tab.

Rajan, S.; Kane, T.J.; Philbrick, C.R. [Pennsylvania State Univ., University Park, PA (United States)] [Pennsylvania State Univ., University Park, PA (United States)

1994-11-15

142

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

143

Active Raman sounding of the earth's water vapor field.  

PubMed

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. PMID:16029854

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

2005-08-01

144

Performance modeling of an airborne Raman water-vapor lidar.  

PubMed

We have developed a sophisticated Raman lidar numerical model to simulate the performance of two ground-based Raman water-vapor lidar systems. After verifying the model using these ground-based measurements, we then used the model to simulate the water-vapor measurement capability of an airborne Raman lidar under both daytime and nighttime conditions for a wide range of water-vapor conditions. The results indicate that, under many circumstances, the daytime measurements possess comparable quality to an existing airborne differential absorption water-vapor lidar whereas the nighttime measurements have improved spatial and temporal resolution. In addition, an airborne Raman lidar can offer measurements that are difficult or impossible with the differential absorption lidar technique. PMID:18357011

Whiteman, D N; Schwemmer, G; Berkoff, T; Plotkin, H; Ramos-Izquierdo, L; Pappalardo, G

2001-01-20

145

Investigation of water vapor motion winds from geostationary satellites  

NASA Technical Reports Server (NTRS)

Motions deduced in animated water vapor imagery from geostationary satellites can be used to infer wind fields in cloudless regimes. For the past several years, CIMSS has been exploring this potentially important source of global-scale wind information. Recently, METEOSAT-3 data has become routinely available to both the U.S. operational and research community. Compared with the current GOES satellite, the METEOSAT has a superior resolution (5 km vs. 16 km) in its water vapor channel. Preliminary work: at CIMSS has demonstrated that wind sets derived from METEOSAT water vapor imagery can provide important upper-tropospheric wind information in data void areas, and can positively impact numerical model guidance in meteorological applications. Specifically, hurricane track forecasts can be improved. Currently, we are exploring methods to further improve the derivation and quality of the water vapor wind sets.

Velden, Christopher

1993-01-01

146

Water vapor and the dynamics of climate changes  

E-print Network

Water vapor is not only Earth's dominant greenhouse gas. Through the release of latent heat when it condenses, it also plays an active role in dynamic processes that shape the global circulation of the atmosphere and thus ...

Schneider, Tapio

147

Performance Modeling of an Airborne Raman Water Vapor Lidar  

NASA Technical Reports Server (NTRS)

A sophisticated Raman lidar numerical model had been developed. The model has been used to simulate the performance of two ground-based Raman water vapor lidar systems. After tuning the model using these ground-based measurements, the model is used to simulate the water vapor measurement capability of an airborne Raman lidar under both day-and night-time conditions for a wide range of water vapor conditions. The results indicate that, under many circumstances, the daytime measurements possess comparable resolution to an existing airborne differential absorption water vapor lidar while the nighttime measurement have higher resolution. In addition, a Raman lidar is capable of measurements not possible using a differential absorption system.

Whiteman, D. N.; Schwemmer, G.; Berkoff, T.; Plotkin, H.; Ramos-Izquierdo, L.; Pappalardo, G.

2000-01-01

148

Pulsed photoacoustic calibration of a differential absorption water vapor lidar  

Microsoft Academic Search

We have designed and constructed a photoacoustic (PA) cell to be used for wavelength calibration in a water vapor differential absorption lidar (DIAL) system. This system will be used to remotely determine atmospheric H2O16 concentrations. The accuracy of these measurements depends critically on the ability to tune to and detune from lines in the water vapor spectrum. Specifically, the signal-to-noise

Anthony V. Dentamaro; Phan D. Dao

2003-01-01

149

Daytime Raman lidar profiling of atmospheric water vapor  

SciTech Connect

Detailed measurements of the distribution of water vapor in the atmosphere are needed for a variety of scientific inquiries, including global climate change and related issues in radiative processes (water vapor is the major greenhouse gas in the atmosphere), and studies of a variety of atmospheric processes such as cloud formation and atmospheric circulation. The Raman lidar is a leading candidate for an instrument capable of the detailed, time- and space-resolved measurements required by these and other studies.

Goldsmith, J.E.M.; Bisson, S.E.

1994-08-01

150

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

151

Gas phase reaction of sulfur trioxide with water vapor  

Microsoft Academic Search

Sulfur trioxide (SO3) has long been known to react with water to produce sulfuric acid (H2S04). It has been commonly assumed that the gas phase reaction in the Earth`s atmosphere between SO3 and water vapor to produce sulfuric acid vapor is an important step in the production of sulfuric acid aerosol particles. The kinetics of the gas phase reaction of

C. E. Kolb; M. J. Molina; J. T. Jayne; R. F. Meads; D. R. Worsnop; A. A. Viggiano

1994-01-01

152

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

153

Spectral probing of impact-generated vapor in laboratory experiments  

NASA Astrophysics Data System (ADS)

High-speed spectra of hypervelocity impacts at the NASA Ames Vertical Gun Range (AVGR) captured the rapidly evolving conditions of impact-generated vapor as a function of impact angle, viewpoint, and time (within the first 50 ?s). Impact speeds possible at the AVGR (<7 km/s) are insufficient to induce significant vaporization in silicates, other than the high-temperature (but low-mass) jetting component created at first contact. Consequently, this study used powdered dolomite as a proxy for surveying the evolution and distribution of chemical constituents within much longer lasting vapor. Seven separate telescopes focused on different portions of the impact vapor plume and were connected through quartz fibers to two 0.35 cm monochromaters. Quarter-space experiments reduced the thermal background and opaque phases due to condensing particles and heated projectile fragments while different exposure times isolated components passing through different the fields of view, both above and below the surface within the growing transient cavity. At early times (<5 ?s), atomic emission lines dominate the spectra. At later times, molecular emission lines dominate the composition of the vapor plume along a given direction. Layered targets and target mixtures isolated the source and reveal that much of the vaporization comes from the uppermost surface. Collisions by projectile fragments downrange also make significant contributions for impacts below 60° (from the horizontal). Further, impacts into mixtures of silicates with powdered dolomite reveal that frictional heating must play a role in vapor production. Such results have implications for processes controlling vaporization on planetary surfaces including volatile release, atmospheric evolution (formation and erosion), vapor generated by the Deep Impact collision, and the possible consequences of the Chicxulub impact.

Schultz, Peter H.; Eberhardy, Clara A.

2015-03-01

154

Atmospheric water vapor measurements - Comparison of microwave radiometry and lidar  

NASA Technical Reports Server (NTRS)

The NASA/GSFC Crustal Dynamics Project microwave water vapor radiometer (J03) is evaluated in terms of measurements of the integrated precipitable water vapor content of a particular column of the troposphere. The measurements were taken during the Atmospheric Moisture Intercomparison Study (ATMIS) held at Wallops Island (Virginia) during April 1989. Water vapor sensing instruments used during ATMIS, included radiometers, radiosondes, and the NASA/GSFC Raman lidar. Comparisons between water vapor measurements by the radiometer and the lidar yielded a correlation coefficient of 0.998 and rms differences for three nights of -0.2 +/- 0.2 mm (April 11-12), -0.8 +/- 0.5 mm (April 16-17), and -0.4 +/- 0.3 mm (April 17-18). The integrated precipitable water vapor measurements for these three nights were approximately 5, 10 and 21 mm, respectively. This study shows that the radiometer provides accurate continuous measurements of the water vapor integrated through the depth of the atmosphere.

England, Martin N.; Ferrare, R. A.; Melfi, S. H.; Whiteman, D. N.; Clark, T. A.

1992-01-01

155

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

156

A WATER VAPOR MONITOR USING DIFFERENTIAL INFRARED ABSORPTION  

EPA Science Inventory

A water vapor monitor has been developed with adequate sensitivity and versatility for a variety of applications. Two applications for which the instrument has been designed are the continuous monitoring of water in ambient air and the measuring of the mass of water desorbed from...

157

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

158

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

159

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

160

Vapor compression distiller and membrane technology for water revitalization  

NASA Technical Reports Server (NTRS)

Water revitalization for a space station can consist of membrane filtration processes and a distillation process. Water recycling equipment using membrane filtration processes was manufactured for ground testing. It was assembled using commercially available components. Two systems for the distillation are studied: one is absorption type thermopervaporation cell and the other is a vapor compression distiller. Absorption type thermopervaporation, able to easily produce condensed water under zero gravity, was investigated experimentally and through simulated calculation. The vapor compression distiller was studied experimentally and it offers significant energy savings for evaporation of water.

Ashida, A.; Mitani, K.; Ebara, K.; Kurokawa, H.; Sawada, I.; Kashiwagi, H.; Tsuji, T.; Hayashi, S.; Otsubo, K.; Nitta, K.

1987-01-01

161

Measurements of daytime and upper tropospheric water vapor profiles by Raman lidar  

Microsoft Academic Search

One of the most important atmospheric constituents needed for climate and meteorological studies is water vapor. Water vapor plays an important role in driving atmospheric circulations through latent heat release and in determining the earth`s radiation budget, both through its radiative effects (water vapor is the major greenhouse gas) and cloud formation. The vertical distribution of water vapor is particularly

S. E. Bisson; J. E. M. Goldsmith

1995-01-01

162

Comparison of columnar water vapor measurement during the fall 1997 ARM Intensive Observation Period: optical methods  

Microsoft Academic Search

Optical methods can provide water vapor data from ground-based, airborne or spaceborne measurements of direct or reflected sunlight in spectral channels in and adjacent to water vapor absorption bands. The water-vapor transmittance Tw derived from these measurements has to be translated into water vapor amounts. Although this relationship is well known qualitatively, it has proven difficult to quantify. Attempts to

B. Schmid; J. Michalsky; D. Slater; J. Barnard; R. Halthore; J. Liljegren; B. Holben; T. Eck; J. Livingston; P. Russell; T. Ingold

2000-01-01

163

High temperature oxidation of molybdenum in water vapor environments  

NASA Astrophysics Data System (ADS)

Molybdenum has recently gained attention as a candidate cladding material for use in light water reactors. Its excellent high temperature mechanical properties and stability under irradiation suggest that it could offer benefits to performance under a wide range of reactor conditions, but little is known about its oxidation behavior in water vapor containing atmospheres. The current study was undertaken to elucidate the oxidation behavior of molybdenum in water vapor environments to 1200 °C in order to provide an initial assessment of its feasibility as a light water reactor cladding. Initial observations indicate that at temperatures below 1000 °C, the kinetics of mass loss in water vapor would not be detrimental to cladding integrity during an off-normal event. Above 1000 °C, degradation is more rapid but remains slower than observed for optimized zirconium cladding alloys. The effect of hydrogen-water vapor and oxygen-water vapor mixtures on material loss was also explored at elevated temperatures. Parts-per-million levels of either hydrogen or oxygen will minimally impact performance, but hydrogen contents in excess of 1000 ppm were observed to limit volatilization at 1000 °C.

Nelson, A. T.; Sooby, E. S.; Kim, Y.-J.; Cheng, B.; Maloy, S. A.

2014-05-01

164

Measurements of Humidity in the Atmosphere: Validation Experiments (MOHAVE I and MOHAVE II). Results Overview and Implication for the Long-Term Lidar Monitoring of Water Vapor in the UT/LS  

NASA Technical Reports Server (NTRS)

1. MOHAVE+MOHAVE II = very successful. 2. MOHAVE -> Fluorescence was found to be inherent to all three participating lidars. 3. MOHAVE II -> Fluorescence was removed and agreement with CFH was extremely good up to 16-18 km altitude. 4. MOHAVE II -> Calibration tests revealed unsuspected shortfalls of widely used techniques, with important implications for their applicability to longterm measurements. 5. A factor of 5 in future lidar signal-to-noise ratio is reasonably achievable. When this level is achieved water vapor Raman lidar will become a key instrument for the long-term monitoring of water vapor in the UT/LS

Leblanc, Thierry; McDermid, I. S.; Vomel, H.; Whiteman, D.; Twigg, Larry; McGee, T. G.

2008-01-01

165

On the uptake of water vapor by ion irradiated polyimide  

NASA Astrophysics Data System (ADS)

It is known that ion-irradiated polymers are capable to adsorb dopants from solid, liquid or gaseous phases. For simple ambient atmosphere exposures, oxygen and water vapor are the most prominent dopants. Though the quantity of the latter one is not sufficient to be probed by conventional spectroscopic techniques, it can be detected indirectly via its ionic conductivity on applying a strong electric field along the track direction, as long as it is not yet masked by the intrinsic ion track conductivity, which is the case for low-fluence polymer irradiation. The conductivity is of similar order for most low-fluence irradiated polymers examined - namely 10-15-10-13 ?-1 cm-1. Water vapor uptake - as determined via the ion track conductivity - sensitively depends on the ambient air humidity, so that fresh low fluence irradiated polymers can act as humidity sensors. Aging however leads to rapid deterioration of this property within a week exposure time at ambient room temperature and pressure. The water vapor absorption process in tracks is reversible, and the amount of water retained depends specifically on the polymer. Thus, whereas for polyimide, polycarbonate, polypropylene, and polytetrafluoride some water vapor adsorption is detected, polymethylmethacrylate and polyethyleneterepthalate exhibit little or no effect. Moreover, uptake of water vapor is restricted to the latent ion tracks themselves, and is barely detectable in neighboring pristine material. It scales linearly with the deposition of electronic energy along the ion track.

Fink, D.; Klett, R.; Müller, M.; Hu, Xuanwen; Chadderton, L. T.; Wang, L.; Hillenbrand, J.

166

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

167

Millimeter-wave Imaging Radiometer (MIR) data processing and development of water vapor retrieval algorithms  

NASA Technical Reports Server (NTRS)

This document describes the progress of the task of the Millimeter-wave Imaging Radiometer (MIR) data processing and the development of water vapor retrieval algorithms, for the second six-month performing period. Aircraft MIR data from two 1995 field experiments were collected and processed with a revised data processing software. Two revised versions of water vapor retrieval algorithm were developed, one for the execution of retrieval on a supercomputer platform, and one for using pressure as the vertical coordinate. Two implementations of incorporating products from other sensors into the water vapor retrieval system, one from the Special Sensor Microwave Imager (SSM/I), the other from the High-resolution Interferometer Sounder (HIS). Water vapor retrievals were performed for both airborne MIR data and spaceborne SSM/T-2 data, during field experiments of TOGA/COARE, CAMEX-1, and CAMEX-2. The climatology of water vapor during TOGA/COARE was examined by SSM/T-2 soundings and conventional rawinsonde.

Chang, L. Aron

1995-01-01

168

Investigation of the Emission and Absorption Spectra of Water Vapor  

NASA Astrophysics Data System (ADS)

Emission and absorption spectra of water vapor are measured and analyzed for temperatures 350-2500 K in the spectral range 0.57-25 ?m. Based on the developed mathematical model of radiative transfer, the parameters of spectral transmission functions of N2O vapors are obtained at different temperatures. Practical application of the obtained radiative characteristics is considered for solving problems of radiative heat exchange in high-temperature media and designing optoelectronic systems intended for monitoring of aero carriers.

Moskalenko, N. I.; Il'in, Yu. A.; Sadykov, M. S.

2015-01-01

169

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

170

Lidar simulation. [measurement of atmospheric water vapor via optical radar  

NASA Technical Reports Server (NTRS)

The feasibility of measuring atmospheric water vapor via orbital lidar is estimated. The calculation starts with laser radar equations representing backscatter with and without molecular line absorption; the magnitudes of off-line backscatter are demonstrated. Extensive prior data on water line strengths are summarized to indicate the available sensitivity to water vapor concentration. Several lidar situations are considered starting with uniform and perturbed atmospheres at 0, 3, 10 and 20 kM (stratosphere) altitudes. These simulations are indicative of results to be obtained in ground truth measurements (ground-based and airborne). An approximate treatment of polar observations is also given. Vertical atmospheric soundings from orbit and from ground stations are calculated. Errors are discussed as regards their propagation through the lidar equation to render the measured water vapor concentration imprecise; conclusions are given as to required laser energy and feasible altitude resolution.

1976-01-01

171

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

172

Steady state analysis of water vapor transport in ionomers  

Microsoft Academic Search

Diffusion coefficients for water in high permeability ionomers are determined from steady state permeation measurements, corrected for boundary layer resistance and change in vapor concentration along sample length, to circumvent problems due to heat of condensation and structural relaxation. Values for water in the perfluoroionomer, Nafion, converted to solvent self-diffusion coefficients, D1, are consistent with the NMR based free volume

N. S. Schneider; D. Rivin

2010-01-01

173

Electrolysis cell functions as water vapor dehumidifier and oxygen generator  

NASA Technical Reports Server (NTRS)

Water vapor is absorbed in hygroscopic electrolyte, and oxygen generated by absorbed water electrolysis at anode is added simultaneously to air stream. Cell applications include on-board aircraft oxygen systems, portable oxygen generators, oxygen concentration requirements, and commercial air conditioning and dehumidifying systems.

Clifford, J. E.

1971-01-01

174

Computer simulation of the NASA water vapor electrolysis reactor  

NASA Technical Reports Server (NTRS)

The water vapor electrolysis (WVE) reactor is a spacecraft waste reclamation system for extended-mission manned spacecraft. The WVE reactor's raw material is water, its product oxygen. A computer simulation of the WVE operational processes provided the data required for an optimal design of the WVE unit. The simulation process was implemented with the aid of a FORTRAN IV routine.

Bloom, A. M.

1974-01-01

175

An observationally based constraint on the water-vapor feedback  

NASA Astrophysics Data System (ADS)

The increase in atmospheric concentrations of water vapor with global warming is a large positive feedback in the climate system. Thus, even relatively small errors in its magnitude can lead to large uncertainties in predicting climate response to anthropogenic forcing. This study incorporates observed variability of water vapor over 2002-2009 from the Atmospheric Infrared Sounder instrument into a radiative transfer scheme to provide constraints on this feedback. We derive a short-term water vapor feedback of 2.2 ± 0.4 Wm-2K-1. Based on the relationship between feedback derived over short and long timescales in twentieth century simulations of 14 climate models, we estimate a range of likely values for the long-term twentieth century water vapor feedback of 1.9 to 2.8 Wm-2K-1. We use the twentieth century simulations to determine the record length necessary for the short-term feedback to approach the long-term value. In most of the climate models we analyze, the short-term feedback converges to within 15% of its long-term value after 25 years, implying that a longer observational record is necessary to accurately estimate the water vapor feedback.

Gordon, N. D.; Jonko, A. K.; Forster, P. M.; Shell, K. M.

2013-11-01

176

Assessment of the SAGE sampling strategy in the derivation of tropospheric water vapor distribution in a general circulation model  

SciTech Connect

The Stratospheric Aerosol and Gas Experiment (SAGE) II has provided unprecedented information of water vapor distribution in the upper troposphere. For the purpose of comparison with output from climate models, the present study assesses the impact of the SAGE II sampling strategy on the tropospheric water vapor climatology in a general circulation model. Since water vapor is sampled only in {open_quotes}non-cloudy{close_quotes} regions in the SAGE strategy, the sampled water vapor concentration is smaller than the real climatology. This difference is associated with two factors. One is the water-vapor sampling frequency, the other is the humidity variability inside and outside the clouds. It is shown that maximum difference is at around 300 to 500 mb where it reaches up to 40% in the zonal mean humidity. 10 refs., 5 figs.

Zhang, M.H. [State Univ. of New York, Stony Brook, NY (United States)] [State Univ. of New York, Stony Brook, NY (United States)

1995-06-01

177

Observations of water vapor and cloud liquid from an airborne dual-frequency radiometer during VORTEX '95  

Microsoft Academic Search

The fine-scale horizontal variations of water vapor and cloud liquid water are of importance to climate, meteorology, and satellite validation\\/calibration. The Environmental Technology Laboratory of NOAA has developed a dual-frequency upward- (and downward-) looking radiometer at 23.87 and 31.65 GHz to measure the integrated amounts of water vapor and cloud liquid above an aircraft. Two experiments involving the NOAA WP-3D

L. S. Fedor; E. R. Westwater; Michael J. Falls

1996-01-01

178

An opacity-sampled treatment of water vapor  

NASA Technical Reports Server (NTRS)

Although the bands of H2O are strong in the spectra of cool stars and calculations have repeatedly demonstrated their significance as opacity sources, only approximate opacities are currently available, due both to the difficulty of accounting for the millions of lines involved and to the inadequacy of laboratory and theoretical data. To overcome these obstacles, a new treatment is presented, based upon a statistical representation of the water vapor spectrum derived from available laboratory data. This statistical spectrum of water vapor employs an exponential distribution of line strengths and random positions of lines whose overall properties are forced to reproduce the mean opacities observed in the laboratory. The resultant data set is then treated by the opacity-sampling method exactly as are all other lines, both molecular and atomic. Significant differences are found between the results of this improved treatment and the results obtained with previous treatments of water-vapor opacity.

Alexander, David R.; Augason, Gordon C.; Johnson, Hollis R.

1989-01-01

179

Combining Suborbital Measurements of Aerosol Optical Depth and Columnar Water Vapor for Satellite Sensor Validations in the CLAMS (Chesapeake Lighthouse and Aircraft Measurements for Satellites) Experiment, 2001  

Microsoft Academic Search

As part of the Chesapeake Lighthouse and Aircraft Measurements for Satellites (CLAMS) experiment, July 10 - August 2, 2001, the 14-channel NASA Ames Airborne Tracking Sunphotometer (AATS-14) was operated successfully aboard the University of Washington Convair-580 during 10 research flights (~45 flight hours). The CLAMS campaign was a clear sky, shortwave (SW) closure campaign that entailed measurements from the Chesapeake

J. Redemann; B. Schmid; J. M. Livingston; P. B. Russell; J. A. Eilers; P. V. Hobbs; R. Kahn; W. L. Smith; B. N. Holben; C. K. Rutledge; M. C. Pitts; M. I. Mishchenko; J. Chowdhary; J. V. Martins; A. Plana-Fattori; T. P. Charlock

2002-01-01

180

A Miniaturized Water Vapor Profiling Radiometer for Network-based 3-D Measurements of the Tropospheric Water Vapor Field  

Microsoft Academic Search

Knowledge of the temporal and spatial distribution of water vapor and liquid water in the troposphere is fundamental for short- and medium-range prediction of precipitation and severe weather. Current measurements of these quantities in the troposphere are limited by optical extinction in clouds (lidar), in temporal resolution (radiosondes), in spatial resolution (GPS networks) and in spatial coverage (microwave radiometers). In

S. C. Reising; F. Iturbide-Sanchez; R. W. Jackson

2005-01-01

181

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

182

Tracking Water Vapor in the Winter High Arctic using the Microwave Humidity Sounder  

NASA Astrophysics Data System (ADS)

The cold and dry conditions during the darkness of the winter High Arctic have been a challenge for the retrieval of tropospheric water vapor amounts from satellites. Water vapor remains the most important greenhouse gas even in these dry conditions and so its variability has a direct bearing on the radiative forcing at the surface. The presence of the surface-based temperature inversion helps to amplify the response of the surface temperature to fluctuations in water vapor column. The ability to track the movement and magnitude of water vapor intrusions into the Arctic has important operational forecast as well as climate implications associated with rapid Arctic warming and sea ice loss. The water vapor field also determines the cloud and precipitation development. The first high temporal and high spatial resolution satellite retrievals of precipitable water in the winter High Arctic without interference from clouds and precipitation were done by Melsheimer and Heygster (2008) using the 5 AMSU-B microwave channels near the strong 183 GHz water vapor line and the window channel at 150 GHz. We have applied their algorithm to the Microwave Humidity Sounder (MHS) that is installed on the NOAA-18, -19 and MetOp-A satellites. The MHS is the next generation instrument replacing the AMSU-B. The retrievals have a sensitivity of less than 0.5 mm of column water with a nadir spatial resolution of 17 km. Numerous passes over the entire Arctic take place every day providing a high resolution map of the distribution of water vapor over the entire Arctic without masking from clouds or precipitation. The calibration procedures, including comparisons with multiple ground-based microwave radiometers, will be presented along with results of the water vapor tracking experiments for the 2009-2010 winter season in the High Arctic. Movies depicting the movement and evolution of the water vapor column will be shown. These show frequent intrusions of lobes of moisture associated with transient cyclogenesis near the Aleutian and Icelandic lows and the removal of moisture by atmospheric transport out of the Arctic rather than solely by precipitation.

Duck, T. J.; Lesins, G. B.; Drummond, J. R.

2010-12-01

183

Calibrated In Situ Measurement of UT/LS Water Vapor Using Chemical Ionization Mass Spectrometry  

NASA Astrophysics Data System (ADS)

Over the past several decades there has been considerable disagreement among in situ water vapor measurements by different instruments at the low part per million (ppm) mixing ratios found in the upper troposphere and lower stratosphere (UT/LS). These discrepancies contribute to uncertainty in our understanding of the microphysics related to cirrus cloud particle nucleation and growth and affect our ability to determine the effect of climate changes on the radiatively important feedback from UT/LS water vapor. To address the discrepancies observed in measured UT/LS water vapor, a new chemical ionization mass spectrometer (CIMS) instrument has been developed for the fast, precise, and accurate measurement of water vapor at low mixing ratios. The instrument utilizes a radioactive ? particle source to ionize a flow of sample air drawn into the instrument. A cascade of ion-molecule reactions results in the production of protonated water ions proportional to the water vapor mixing ratio that are then detected by the mass spectrometer. The multi-step nature of the ionization mechanism results in a non-linear sensitivity to water vapor, necessitating calibration across the full range of values to be measured. To accomplish this calibration, we have developed a novel calibration scheme using catalytic oxidation of hydrogen to produce well-defined water vapor mixing ratios that can be introduced into the instrument inlet during flight. The CIMS instrument was deployed for the first time aboard the NASA WB-57 high altitude research aircraft during the Mid-latitude Airborne Cirrus Properties Experiment (MACPEX) mission in March and April 2011. The sensitivity of the instrument to water vapor was calibrated every ~45 minutes in flight from < 1 to 150 ppm. Analysis of in-flight data demonstrates a typical sensitivity of 2000 Hz/ppm at 4.5 ppm with a signal to noise ratio (2 ?) > 50 for a 1 second measurement. The instrument and its calibration system performed successfully in 7 flights during the MACPEX mission, sampling water vapor mixing ratios as low as 4 ppm in stratospheric air. A comparison of the new measurement with other measurements on board the aircraft is expected to help resolve the long-standing differences in low water measurements in the lower stratosphere.

Thornberry, T. D.; Rollins, A.; Gao, R.; Watts, L. A.; Ciciora, S. J.; McLaughlin, R. J.; Fahey, D. W.

2011-12-01

184

Ultrafast Room-Temperature Crystallization of TiO2 Nanotubes Exploiting Water-Vapor Treatment  

PubMed Central

In this manuscript a near-room temperature crystallization process of anodic nanotubes from amorphous TiO2 to anatase phase with a fast 30 minutes treatment is reported for the first time. This method involves the exposure of as-grown TiO2 nanotubes to water vapor flow in ambient atmosphere. The water vapor-crystallized samples are deeply investigated in order to gain a whole understanding of their structural, physical and chemical properties. The photocatalytic activity of the converted material is tested by dye degradation experiment and the obtained performance confirms the highly promising properties of this low-temperature processed material. PMID:25589038

Lamberti, Andrea; Chiodoni, Angelica; Shahzad, Nadia; Bianco, Stefano; Quaglio, Marzia; Pirri, Candido F.

2015-01-01

185

Ultrafast Room-Temperature Crystallization of TiO2 Nanotubes Exploiting Water-Vapor Treatment.  

PubMed

In this manuscript a near-room temperature crystallization process of anodic nanotubes from amorphous TiO2 to anatase phase with a fast 30 minutes treatment is reported for the first time. This method involves the exposure of as-grown TiO2 nanotubes to water vapor flow in ambient atmosphere. The water vapor-crystallized samples are deeply investigated in order to gain a whole understanding of their structural, physical and chemical properties. The photocatalytic activity of the converted material is tested by dye degradation experiment and the obtained performance confirms the highly promising properties of this low-temperature processed material. PMID:25589038

Lamberti, Andrea; Chiodoni, Angelica; Shahzad, Nadia; Bianco, Stefano; Quaglio, Marzia; Pirri, Candido F

2015-01-01

186

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

187

Ultrafast Room-Temperature Crystallization of TiO2 Nanotubes Exploiting Water-Vapor Treatment  

NASA Astrophysics Data System (ADS)

In this manuscript a near-room temperature crystallization process of anodic nanotubes from amorphous TiO2 to anatase phase with a fast 30 minutes treatment is reported for the first time. This method involves the exposure of as-grown TiO2 nanotubes to water vapor flow in ambient atmosphere. The water vapor-crystallized samples are deeply investigated in order to gain a whole understanding of their structural, physical and chemical properties. The photocatalytic activity of the converted material is tested by dye degradation experiment and the obtained performance confirms the highly promising properties of this low-temperature processed material.

Lamberti, Andrea; Chiodoni, Angelica; Shahzad, Nadia; Bianco, Stefano; Quaglio, Marzia; Pirri, Candido F.

2015-01-01

188

Water vapor from new Microwave Limb Sounder on Aura (WMS)  

NSDL National Science Digital Library

Water vapor (H2O) in the atmosphere as measured by the Microwave Limb Sounder (MLS) instrument on NASAs Aura satellite. MLS can simultaneously measure several trace gases and ozone-destroying chemicals in the upper troposphere and photosphere. In this series of animiations we present chlorine monoxide (ClO), hydrogen chloride (HCl), nitric acid (HNO3), ozone (O3), water vapor (H2O) and temperature measurements. These are first light data taken when the MLS was operated for the first time.

Lori Perkins

2005-01-27

189

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

190

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

2014-12-01

191

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

192

Water Vapor Tracers as Diagnostics of the Regional Hydrologic Cycle  

NASA Technical Reports Server (NTRS)

Numerous studies suggest that local feedback of evaporation on precipitation, or recycling, is a significant source of water for precipitation. Quantitative results on the exact amount of recycling have been difficult to obtain in view of the inherent limitations of diagnostic recycling calculations. The current study describes a calculation of the amount of local and remote sources of water for precipitation, based on the implementation of passive constituent tracers of water vapor (termed water vapor tracers, WVT) in a general circulation model. In this case, the major limitation on the accuracy of the recycling estimates is the veracity of the numerically simulated hydrological cycle, though we note that this approach can also be implemented within the context of a data assimilation system. In this approach, each WVT is associated with an evaporative source region, and tracks the water until it precipitates from the atmosphere. By assuming that the regional water is well mixed with water from other sources, the physical processes that act on the WVT are determined in proportion to those that act on the model's prognostic water vapor. In this way, the local and remote sources of water for precipitation can be computed within the model simulation, and can be validated against the model's prognostic water vapor. Furthermore, estimates of precipitation recycling can be compared with bulk diagnostic approaches. As a demonstration of the method, the regional hydrologic cycles for North America and India are evaluated for six summers (June, July and August) of model simulation. More than 50% of the precipitation in the Midwestern United States came from continental regional tracers, and the local source was the largest of the regional tracers (14%). The Gulf of Mexico and Atlantic 2 regions contributed 18% of the water for Midwestern precipitation, but further analysis suggests that the greater region of the Tropical Atlantic Ocean may also contribute significantly. In general, most North American land regions showed a positive correlation between evaporation and recycling ratio (except the Southeast United States) and negative correlations of recycling ratio with precipitation and moisture transport (except the Southwestern United States). The Midwestern local source is positively correlated with local evaporation, but it is not correlated with water vapor transport. This is contrary to bulk diagnostic estimates of precipitation recycling. In India, the local source of precipitation is a small percentage of the precipitation owing to the dominance of the atmospheric transport of oceanic water. The southern Indian Ocean provides a key source of water for both the Indian continent and the Sahelian region.

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

2001-01-01

193

Cassini/CIRS Observations of Water Vapor in Saturn's Stratosphere  

NASA Technical Reports Server (NTRS)

The Composite Infrared Spectrometer (CIRS) on the Cassini spacecraft has obtained numerous spectra of Saturn at varying spectral and spatial resolutions since Saturn Orbit Insertion in 2004. Emission lines due to water vapor in Saturn's stratosphere were first detected using whole-disk observations from the Infrared Space Observatory (Feuchtgruber et al 1997) and subsequently confirmed by the Submillimeter Wave Astronomy Satellite (Rergin et al 2000). CIRS has detected water and the data permit the retrieval of the latitudinal variation of water on Saturn. Emission lines of H2O on Saturn are very weak in the CIRS data. Thus. large spectral averages as well as improvements in calibration are necessary to detect water vapor. Zonally averaged nadir spectra were produced every 10 degrees of latitude. Stratospheric temperatures in the 0.5 - 5.0 mbar range were obtained by inverting spectra of CH4 in the v4 band centered at 1304 cm(exp -1). The origin of water vapor is believed to be from the ablation of micrometeorites containing water ice, followed by photochemistry. This external source of oxygen originates either from the Saturn system (from the rings or perhaps from Enceladus) or from the interplanetary medium. Connerney (1986) proposed a mechanism to transport water from the inner edge of the B-ring along magnetic field lines to specific latitudes (50N and 44S) on Saturn. Prange et al (2006) interpreted a minimum in the abundance of acetylene from ultraviolet spectra near 41S on Saturn as possibly due to an enhanced influx of water. Existing CIRS far-IR spectra are at relatively low spatial resolution, but observations at closer range planned for the extended mission will be able to test the "ring rain" mechanism by searching for localized water vapor enhancement at midlatitudes.

Bjoraker, G. L.; Achterberg, R. K.; Simon-Miller, A. A.; Carlson, R. C.; Jennings, D. E.

2008-01-01

194

Tropospheric water vapor measurements with an airborne lidar system  

NASA Technical Reports Server (NTRS)

A differential absorption lidar system has been developed for the remote measurement of atmospheric water vapor and aerosol distributions from an aircraft. The first extensive observations of H2O and aerosols in the lower troposphere made with this system are briefly discussed.

Browell, E. V.; Higdon, N. S.; Butler, C. F.; Fenn, M. A.; Grossmann, B. E.; Ponsardin, P.; Grant, W. B.; Bachmeier, A. S.

1991-01-01

195

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

196

DMSP SSM\\/T-2 microwave water vapor profiler  

Microsoft Academic Search

The Special Sensor Microwave water vapor profiler (SSM\\/T-2) is a five channel passive microwave sensor that operates in the 90 - 190 GHz frequency band. The instrument was developed by Aerojet Electronic Systems Division (AESD) of GenCorp Aerojet under a contract to the Defense Meteorological Satellite Program (DMSP). The first in a series of these instruments was successfully orbited in

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

1993-01-01

197

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...

198

Experimental Study of Water Vapor Adsorption on Geothermal  

E-print Network

SGP-TR-148 Experimental Study of Water Vapor Adsorption on Geothermal Reservoir Rocks Shubo Shang Geothermal Program under Department of Energy Grant No. DE-FG07-90IDI2934,and by the Department of Petroleum Engineering, Stanford University Stanford Geothermal Program Interdisciplinary Research in Engineering

Stanford University

199

Advanced Detector and Waveform Digitizer for Water Vapor DIAL Systems  

NASA Technical Reports Server (NTRS)

Measurement of atmospheric water vapor has become a major requirement for understanding moist-air processes. Differential absorption lidar (DIAL) is a technique best suited for the measurement of atmospheric water vapor. NASA Langley Research Center is continually developing improved DIAL systems. One aspect of current development is focused on the enhancement of a DIAL receiver by applying state-of-the-art technology in building a new compact detection system that will be placed directly on the DIAL receiver telescope. The newly developed detection system has the capability of being digitally interfaced with a simple personal computer, using a discrete input/output interface. This has the potential of transmitting digital data over relatively long distances instead of analog signals, which greatly reduces measurement noise. In this paper, we discuss some results from the new compact water vapor DIAL detection system which includes a silicon based avalanche photodiode (APD) detector, a 14-bit, 10-MHz waveform digitizer, a microcontroller and other auxiliary electronics. All of which are contained on a small printed-circuit-board. This will significantly reduce the weight and volume over the current CAMAC system and eventually will be used in a water vapor DIAL system on an unpiloted atmospheric vehicle (UAV) aircraft, or alternatively on an orbiting spacecraft.

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

1998-01-01

200

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

201

Water vapor plasma technology for biomass conversion to synthetic gas  

Microsoft Academic Search

This study presents the results of experimental investigation on the development of water vapor plasma technology for conversion of biomass and destruction of hazardous substances. Similar plasma technology is also foreseen for the synthesis of micro- and nanostructured catalytic coatings for wide range of applications.An experimental DC plasma torch with button type hot cathode and step formed copper anode, operating

V. Grigaitien?; V. Snapkauskien?; P. Valatkevi?ius; A. Tamoši?nas; V. Valin?ius

2011-01-01

202

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

203

Preliminary Design Program: Vapor Compression Distillation Flight Experiment Program  

NASA Technical Reports Server (NTRS)

This document provides a description of the results of a program to prepare a preliminary design of a flight experiment to demonstrate the function of a Vapor Compression Distillation (VCD) Wastewater Processor (WWP) in microgravity. This report describes the test sequence to be performed and the hardware, control/monitor instrumentation and software designs prepared to perform the defined tests. the purpose of the flight experiment is to significantly reduce the technical and programmatic risks associated with implementing a VCD-based WWP on board the International Space Station Alpha.

Schubert, F. H.; Boyda, R. B.

1995-01-01

204

Microwave methods of atmospheric temperature and water vapor profiling  

Microsoft Academic Search

A temperature profiling radiometer based on a highly stable synthesizer, rather than traditionally used Gunn oscillators, has been designed and fabricated under contract to White Sands Missile Range. This profiler is capable of tuning a user-selected ensemble of frequencies in the range of 52.85 to 58.8 GHz as well as fixed water vapor and water channels at 25.8 and 31.4

Fredrick Solheim

1995-01-01

205

New VLA Observations of Mars Atmospheric Water Vapor  

NASA Astrophysics Data System (ADS)

The presence of water vapor in the atmosphere of Mars is becoming increasingly recognized as a key element of that planet's climate. Previous studies have characterized latitudinal and seasonal variations in the quantity and transport of water vapor, but detailed information regarding its distribution as a function of altitude, and how that changes with season, is still lacking. One method of determining the vertical distribution is via spectroscopic observations of the 1.35-cm rotational transition (Clancy et al. 1992, Icarus, 100, 48; Clancy et al. 1996, Icarus, 122, 36). Shortly after the 2003 opposition, such observations were conducted with the Very Large Array (VLA). The observations were taken on four dates, in two high resolution configurations of the VLA. These observations provide a good combination of sensitivity and spatial resolution for mapping the martian atmospheric water vapor. The shape of the line can be used to infer a vertical profile, and spatial variations around the limb give information on the latitudinal and local time distributions of water vapor. The season on Mars during these observations (Ls=265-285, around southern summer solstice) is of particular interest, as the water vapor supplied to the atmosphere from the south polar cap at that time appears to vary significantly from year to year. These observations can be compared to a number of contemporaneous observations from other instruments, including the Mars Global Surveyor Thermal Emission Spectrometer (MGS TES), the Submillimeter Wave Astronomy Satellite (SWAS) and the Submillimeter Array (SMA). Results from the preliminary analysis of these new data will be presented and implications discussed.

Butler, B. J.; Johnston, J. G.; Clancy, R. T.; Gurwell, M. A.

2005-08-01

206

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

207

Development of a microbalance system for dust and water vapor detection in the Mars atmosphere  

NASA Astrophysics Data System (ADS)

Water vapor and dust are among the most important gauges of atmospheric behaviour on Mars. The cycle of dust on Mars is a key component of current climate, is relevant in the dynamic and thermodynamic evolution of atmosphere, and is directly involved in the water cloud formation. On the other hand water vapor is important as indicator of global climate changes on long time-scale. Quartz crystal piezoelectric sensors are suitable for analyses that need very high sensitivity. Due to the wide working ranges (five orders of magnitude) and high sensitivity (10-6 - 10-11 g), microbalances can measure the mass settling in average Mars conditions during months before saturation is reached. This ensures a proper use for short and long term water and dust variations monitoring. These instruments were already studied, calibrated and used for the GIADA (Grain Impact And Dust Accumulator) - Rosetta project. Long experience on microbalance performance study by dust deposition has acquired and a simulation chamber of Martian atmosphere, for water vapor deposition studies, has been prepared. First preliminary results are achieved and the configuration of a microbalance system for cross analyses of dust and water vapor depositions is in progress.

Battaglia, R.; Palomba, E.; Palumbo, P.; Colangeli, L.

208

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

209

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

210

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

SciTech Connect

The FIRE/SPECTRE field campaign was conducted during November- December 1991 in Coffeyville, Kansas. The main objective of FIRE (First ISCCP (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. A complete understanding of water vapor, its distribution with height, and its temporal variation was important for both experiments. A ground-based Raman Lidar was deployed at Coffeyville, Kansas from November 12 until December 7, 1991. During the campaign, the lidar operated during 14 observation periods. The periods ranged in length from 3.5 hours to 12 hours for a total operating time of approximately 119 hours. During each of the operational periods the lidar obtained vertical profiles of water vapor mixing ratio and aerosol scattering ratio once every minute with vertical resolution of 75 meters from near the earth's surface to an altitude of 9--10 km for water vapor and higher for aerosols. Several balloon-sondes were launched during each operational period providing an independent measurement of humidity with altitude. For each operational period, the 1-minute profiles of water vapor mixing ratio and aerosol scattering ratio are composited to give a color- coded time-height display of water vapor and aerosol scattering, respectively.

Melfi, S.H.; Whiteman, D. (National Aeronautics and Space Administration, Greenbelt, MD (United States). Goddard Space Flight Center); Ferrare, R. (Universities Space Research Associates, Columbia, MD (United States)); Evans, K. (Hughes-STX, Lanham, MD (United States)); Goldsmith, J.E.M.; Lapp, M.; Bisson, S.E. (Sandia National Labs., Livermore, CA (United States))

1992-01-01

211

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

SciTech Connect

The FIRE/SPECTRE field campaign was conducted during November- December 1991 in Coffeyville, Kansas. The main objective of FIRE [First ISCCP (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. A complete understanding of water vapor, its distribution with height, and its temporal variation was important for both experiments. A ground-based Raman Lidar was deployed at Coffeyville, Kansas from November 12 until December 7, 1991. During the campaign, the lidar operated during 14 observation periods. The periods ranged in length from 3.5 hours to 12 hours for a total operating time of approximately 119 hours. During each of the operational periods the lidar obtained vertical profiles of water vapor mixing ratio and aerosol scattering ratio once every minute with vertical resolution of 75 meters from near the earth`s surface to an altitude of 9--10 km for water vapor and higher for aerosols. Several balloon-sondes were launched during each operational period providing an independent measurement of humidity with altitude. For each operational period, the 1-minute profiles of water vapor mixing ratio and aerosol scattering ratio are composited to give a color- coded time-height display of water vapor and aerosol scattering, respectively.

Melfi, S.H.; Whiteman, D. [National Aeronautics and Space Administration, Greenbelt, MD (United States). Goddard Space Flight Center; Ferrare, R. [Universities Space Research Associates, Columbia, MD (United States); Evans, K. [Hughes-STX, Lanham, MD (United States); Goldsmith, J.E.M.; Lapp, M.; Bisson, S.E. [Sandia National Labs., Livermore, CA (United States)

1992-07-01

212

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

213

NASA/GSFC Scanning Raman Lidar Measurements of Water Vapor and Cirrus Clouds during WVIOP2000 and AFWEX  

NASA Technical Reports Server (NTRS)

The NASA/GSFC Scanning Raman Lidar (SRL) was deployed to the Southern Great Plains CART site from September - December, 2000 and participated in two field campaigns devoted to comparisons of various water vapor measurement technologies and calibrations. These campaigns were the Water Vapor Intensive Operations Period 2000 (WVIOP2000) and the ARM FIRE Water Vapor Experiment (AFWEX). WVIOP2000 was devoted to validating water vapor measurements in the lower atmosphere while AFWEX had similar goals but for measurements in the upper troposphere. The SRL was significantly upgraded both optically and electronically prior to these field campaigns. These upgrades enabled the SRL to demonstrate the highest resolution lidar measurements of water vapor ever acquired during the nighttime and the highest S/N Raman lidar measurements of water vapor in the daytime; more than a factor of 2 increase in S/N versus the DOE CARL Raman Lidar. Examples of these new measurement capabilities along with comparisons of SRL and CARL, LASE, MPI-DIAL, in-situ sensors, radiosonde, and others will be presented. The profile comparisons of the SRL and CARL have revealed what appears to be an overlap correction or countrate correction problem in CARL. This may be involved in an overall dry bias in the precipitable water calibration of CARL with respect to the MWR of approx. 4%. Preliminary analysis indicates that the application of a temperature dependent correction to the narrowband Raman lidar measurements of water vapor improves the lidar/Vaisala radiosonde comparisons of upper tropospheric water vapor. Other results including the comparison of the first-ever simultaneous measurements from four water vapor lidar systems, a bore-wave event captured at high resolution by the SRL and cirrus cloud optical depth studies using the SRL and CARL will be presented at the meeting.

Whiteman, D. N.; Evans, K. D.; DiGirolamo, P.; Demoz, B. B.; Turner, D.; Comstock, J.; Ismail, S.; Ferrare, R. A.; Browell, E. V.; Goldsmith, J. E. M.; Abshire, James B. (Technical Monitor)

2002-01-01

214

Preliminary endurance tests of water vaporizers for resistojet applications  

NASA Astrophysics Data System (ADS)

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. E.; Macrae, Gregory S.

1993-06-01

215

Water Vapor Tracers as Diagnostics of the Regional Hydrologic Cycle  

NASA Technical Reports Server (NTRS)

Numerous studies suggest that local feedback of surface evaporation on precipitation, or recycling, is a significant source of water for precipitation. Quantitative results on the exact amount of recycling have been difficult to obtain in view of the inherent limitations of diagnostic recycling calculations. The current study describes a calculation of the amount of local and remote geographic sources of surface evaporation for precipitation, based on the implementation of three-dimensional constituent tracers of regional water vapor sources (termed water vapor tracers, WVT) in a general circulation model. The major limitation on the accuracy of the recycling estimates is the veracity of the numerically simulated hydrological cycle, though we note that this approach can also be implemented within the context of a data assimilation system. In the WVT approach, each tracer is associated with an evaporative source region for a prognostic three-dimensional variable that represents a partial amount of the total atmospheric water vapor. The physical processes that act on a WVT are determined in proportion to those that act on the model's prognostic water vapor. In this way, the local and remote sources of water for precipitation can be predicted within the model simulation, and can be validated against the model's prognostic water vapor. As a demonstration of the method, the regional hydrologic cycles for North America and India are evaluated for six summers (June, July and August) of model simulation. More than 50% of the precipitation in the Midwestern United States came from continental regional sources, and the local source was the largest of the regional tracers (14%). The Gulf of Mexico and Atlantic regions contributed 18% of the water for Midwestern precipitation, but further analysis suggests that the greater region of the Tropical Atlantic Ocean may also contribute significantly. In most North American continental regions, the local source of precipitation is correlated with total precipitation. There is a general positive correlation between local evaporation and local precipitation, but it can be weaker because large evaporation can occur when precipitation is inhibited. In India, the local source of precipitation is a small percentage of the precipitation owing to the dominance of the atmospheric transport of oceanic water. The southern Indian Ocean provides a key source of water for both the Indian continent and the Sahelian region.

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

2001-01-01

216

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

217

Preliminary measurements of tropospheric water vapor using Raman lidar system in the Great Lakes area  

Microsoft Academic Search

Obtaining high resolution vertical profiles of water vapor is crucially important to understand short and long term global climate changes. Raman lidar technique is widely recognized as the most effective tool to study water vapor and aerosols profiles in the lower atmosphere. The Great lakes area is one of the ideal areas to study the environmental impact of water vapor

Watheq Al-Basheer; Kevin B. Strawbridge; Bernard J. Firanski

2011-01-01

218

Retrieval of 3-D Water Vapor Field Using a Network of Scanning Compact Microwave Radiometers  

Microsoft Academic Search

Quantitative precipitation forecasting is currently limited by the paucity of observations of thermodynamic variables in the troposphere, including water vapor. Specifically, measurements of 3-D water vapor fields are needed at sub-meso-?? scales in pre- storm conditions. This can be achieved using a network of remote sensors to retrieve the water vapor field with high spatial and temporal resolution. Such measurements

Sharmila Padmanabhan; Steven C. Reising; Jothiram Vivekanandan

2008-01-01

219

A Remotely Operated Lidar for Aerosol, Temperature, and Water Vapor Profiling in the High Arctic  

E-print Network

A Remotely Operated Lidar for Aerosol, Temperature, and Water Vapor Profiling in the High Arctic G of higher temporal resolu- tion are required. Lidar measurements of tropospheric water vapor have been coefficients, depolarization ratio, tropospheric temperature, and water vapor mixing ratio. Variable field

Duck, Thomas J.

220

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

E-print Network

2.1 RAMAN LIDAR PROFILING OF WATER VAPOR AND AEROSOLS OVER THE ARM SGP SITE Richard A. Ferrare *1-the-clock profiling of water vapor and aerosols (Goldsmith et al., 1998). These Raman lidar profiles are important; Turner et al., 1999). These aerosol and water vapor profiles (Raman lidar) and temperature profiles (AERI

221

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

E-print Network

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 Alamos National Laboratory's volume-imaging water-vapor Raman lidar system was used to estimate

Williams, David G.

222

Correlation Between Opacity and Surface Water Vapor Pressure Measurements at Rio Frio  

E-print Network

Correlation Between Opacity and Surface Water Vapor Pressure Measurements at Rio Frio M.A. Holdaway 1, 1996 Abstract We use the surface water vapor pressure measured by weather stations at 4060 m opacity. The surface water vapor pressure is inverted some 20% of the time at night and some 35

Groppi, Christopher

223

Measurements of the Vapor Pressure of Supercooled Water Using Infrared Spectroscopy  

E-print Network

Measurements of the Vapor Pressure of Supercooled Water Using Infrared Spectroscopy WILL CANTRELL 14 May 2007, in final form 6 December 2007) ABSTRACT Measurements are presented of the vapor pressure' data correspond to the vapor pressure of liquid water, not a mixture of liquid water and ice. Values

Kostinski, Alex

224

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

225

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

226

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

227

Development of a preprototype vapor compression distillation water recovery subsystem  

NASA Technical Reports Server (NTRS)

The activities involved in the design, development, and test of a preprototype vapor compression distillation water recovery subsystem are described. This subsystem, part of a larger regenerative life support evaluation system, is designed to recover usable water from urine, urinal rinse water, and concentrated shower and laundry brine collected from three space vehicle crewmen for a period of 180 days without resupply. Details of preliminary design and testing as well as component developments are included. Trade studies, considerations leading to concept selections, problems encountered, and test data are also presented. The rework of existing hardware, subsystem development including computer programs, assembly verification, and comprehensive baseline test results are discussed.

Johnson, K. L.

1978-01-01

228

Climatic effects of atmospheric water vapor distribution through volcanic eruptions  

NASA Astrophysics Data System (ADS)

Volcanic eruptions play an important role in changing the water vapor distribution of the atmosphere. In comparison with the emission of carbon dioxide released during the consumption of fossil fuel, water vapor's role in climate change has been grossly underestimated. Studies made of modern volcanic eruptions, including satellite images and meteorological records, have revealed climatic effects in different parts of the globe through the migration of volcanic clouds, depending mainly on their timing, location, Volcanic Explosivity Index (VEI) and composition. The climatic effects of volcanic eruptions include: (1) Reduction in solar heating because of the particulates discharged. (2) Interference with the 'normal' atmospheric circulation and/or oceanic circulation. (3) The ash particles and aerosols provide condensation nuclei for water. (4) The transfer from the troposphere into the stratosphere of water vapor which act as a greenhouse gas more important than carbon dioxide. (5) Variability in regional rainfall including the occurrence of droughts, floods, landslides salinization and crop failures. (6) Anomalous regional wind and rain storms. (7) Acid rain. Selected volcanic eruptions will be used as examples to illustrate the different climatic effects.

Yim, W. W.

2011-12-01

229

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

230

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

231

Diode laser based water vapor DIAL using modulated pulse technique  

NASA Astrophysics Data System (ADS)

In this paper, we propose a diode laser based differential absorption lidar (DIAL) for measuring lower-tropospheric water vapor profile using the modulated pulse technique. The transmitter is based on single-mode diode laser and tapered semiconductor optical amplifier with a peak power of 10W around 800nm absorption band, and the receiver telescope diameter is 35cm. The selected wavelengths are compared to referenced wavelengths in terms of random error and systematic errors. The key component of modulated pulse technique, a macropulse, is generated with a repetition rate of 10 kHz, and the modulation within the macropulse is coded according to a pseudorandom sequence with 100ns chip width. As a result, we evaluate both single pulse modulation and pseudorandom coded pulse modulation technique. The water vapor profiles conducted from these modulation techniques are compared to the real observation data in summer in Japan.

Pham, Phong Le Hoai; Abo, Makoto

2014-11-01

232

Profiling atmospheric water vapor using a fiber laser lidar system.  

PubMed

A compact, lightweight, and efficient fiber laser lidar system has been developed to measure water vapor profiles in the lower atmosphere of Earth or Mars. The line narrowed laser consist of a Tm:germanate fiber pumped by two 792 nm diode arrays. The fiber laser transmits approximately 0.5 mJ Q- switched pulses at 5 Hz and can be tuned to water vapor lines near 1.94 microm with linewidth of approximately 20 pm. A lightweight lidar receiver telescope was constructed of carbon epoxy fiber with a 30 cm Fresnel lens and an advanced HgCdTe APD detector. This system has made preliminary atmospheric measurements. PMID:20119001

De Young, Russell J; Barnes, Norman P

2010-02-01

233

Water vapor detection system based on scanning spectra  

NASA Astrophysics Data System (ADS)

Scanning the absorption spectral line of water vapor through wavelength around 1368.597nm is successfully used to measure the value of micro-moisture content. The synchronous superposition average of original signal algorithm based on labview is innovated and applied to detecting weak spectrum absorption signal instead of low pass filter. Two data processing methods are used to get the concentration of water vapor in ppm: one is a general formula method which has newly deduced a general formula to calculate the concentration of gas with temperature and beam intensity ratio when the pressure is equal to or greater than 1 atm; the other is engineering calibration method which is proved to have high resolution and accuracy with the fitted curve of beam intensity ratio and concentration in ppm when the temperature changes form 258 K to 305 K and the pressure ranges from 1atm to 5 atm.

Zhang, Shicong; Wang, Qiang; Zhang, Yan; Song, Fujun; Chen, Kun; Chou, Guoqing; Chang, Jun; Wang, Pengpeng; Kong, Delong; Wang, Zongliang; Wang, Weijie; Liu, Yongning; Song, Haiyong

2012-03-01

234

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

235

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

236

Water vapor and the dynamics of climate changes  

E-print Network

Water vapor is not only Earth's dominant greenhouse gas. Through the release of latent heat when it condenses, it also plays an active role in dynamic processes that shape the global circulation of the atmosphere and thus climate. Here we present an overview of how latent heat release affects atmosphere dynamics in a broad range of climates, ranging from extremely cold to extremely warm. Contrary to widely held beliefs, atmospheric circulation statistics can change non-monotonically with global-mean surface temperature, in part because of dynamic effects of water vapor. For example, the strengths of the tropical Hadley circulation and of zonally asymmetric tropical circulations, as well as the kinetic energy of extratropical baroclinic eddies, can be lower than they presently are both in much warmer climates and in much colder climates. We discuss how latent heat release is implicated in such circulation changes, particularly through its effect on the atmospheric static stability, and we illustrate the circul...

Schneider, Tapio; Levine, Xavier

2009-01-01

237

High-resolution spectroscopy of cool K and M stars through the telluric water vapor absorption band near 9360 A. 1: Methodology and first results  

Microsoft Academic Search

An observational program has been undertaken for the study of stellar spectra within telluric water vapor lines absorption region near 9360 A. This program has been developed in the future context of a European Space Agency's (ESAs) environment-dedicated experiment designed to probe atmospheric water vapor absorption with cool star spectrophotometry. With ground observations presented here, we determine absorption levels and

T. Widemann; J.-L. Bertaux; M. Querci; F. Querci

1994-01-01

238

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

239

Prospects for an economical, eye-safe water vapor lidar  

Microsoft Academic Search

A conceptual design and simulations are presented to explore the feasibility for an economical, eye-safe water vapor lidar. The design is based on using GaAlAs laser diode arrays in the lidar transmitter and photon counting silicon avalanche photodiodes (APDs) in the lidar receiver. Simulations are presented to demonstrate that a lidar using a laser diode powered transmitter and an APD

J. A. Reagan; T. W. Cooley; J. A. Shaw

1993-01-01

240

Apparent temperature dependence on localized atmospheric water vapor  

NASA Astrophysics Data System (ADS)

The atmosphere is a critical factor in remote sensing. Radiance from a target must pass through the air column to reach the sensor. The atmosphere alters the radiance reaching the sensor by attenuating the radiance from the target via scattering and absorption and by introducing an upwelling radiance. In the thermal infrared, these effects will introduce errors in the derived apparent temperature of the target if not properly accounted for. The temperature error is defined as the difference between the target leaving apparent temperature and observed apparent temperature. The effects of the atmosphere must be understood in order to develop methods to compensate for this error. Different atmospheric components will affect the radiation passing through it in different ways. Certain components may be more important than others depending on the remote sensing application. The authors are interested in determining the actual temperature of the superstructure that composes a mechanical draft cooling tower (MDCT), hence water vapor is the primary constituent of concern. The tower generates a localized water vapor plume located between the target and sensor. The MODTRAN radiative transfer code is used to model the effects of a localized exhaust plume from a MDCT in the longwave infrared. The air temperature and dew point depression of the plume and the thickness of the plume are varied to observe the effect on the apparent temperature error. In addition, the general atmospheric conditions are varied between two standard MODTRAN atmospheres to study any effect that ambient conditions have on the apparent temperature error. The Digital Imaging and Remote Sensing Image Generation (DIRSIG) modeling tool is used to simulate the radiance reaching a thermal sensor from a target after passing through the water vapor plume. The DIRSIG results are validated against the MODTRAN results. This study shows that temperature errors of as much as one Kelvin can be attributed to the presence of a localized water vapor plume.

Montanaro, Matthew; Salvaggio, Carl; Brown, Scott D.; Messinger, David W.; Garrett, Alfred J.

2008-04-01

241

Improved broadband emissivity parameterization for water vapor cooling rate calculations  

Microsoft Academic Search

Reference transmissivities based on line-by-line calculations have been computed for a wide range of homogeneous paths of water vapor. A new approach is employed in which wideband emissivities are directly fitted to the line-by-line reference calculations without using the intermediate step of narrowband models. A significant improvement in accuracy is obtained over previous schemes. Compared with line-by-line computed fluxes and

Weyni Zhong; J. D. Haigh

1995-01-01

242

Fiber-based lidar for atmospheric water-vapor measurements.  

PubMed

The design and evaluation of a prototype fiber-based lidar system for autonomous measurement of atmospheric water vapor are presented. The system components are described, along with current limitations and options for improvement. Atmospheric measurements show good agreement with modeled signal returns from 400 to 1000 m but are limited below 400 m as a result of errors in signal processing caused by violation of the assumptions used in the derivation of the differential absorption lidar equation. PMID:18360367

Little, L M; Papen, G C

2001-07-20

243

Simultaneous inversion for temperature and water vapor from IMG radiances  

NASA Astrophysics Data System (ADS)

Simultaneous retrieval of temperature and water vapor profiles have been obtained by using spectral radiances from the Japanese IMG high resolution interferometer spectrometer. Forward model computations have been performed with the LBLRTM code. The spectral residuals between the IMG measurements and the LBLRTM radiative transfer model are dominated by uncertainty in the IMG spectral instrument function. The impact of these residuals on the retrievals has been significantly mitigated though an approach using reduced resolution.

Lubrano, Alberta M.; Serio, C.; Clough, Shepard A.; Kobayashi, H.

2000-08-01

244

Solar radiation and water vapor pressure to forecast chickenpox epidemics.  

PubMed

The clear seasonality of varicella infections in temperate regions suggests the influence of meteorologic conditions. However, there are very few data on this association. The aim of this study was to determine the seasonal pattern of varicella infections on the Mediterranean island of Mallorca (Spain), and its association with meteorologic conditions and schooling. Data on the number of cases of varicella were obtained from the Network of Epidemiologic Surveillance, which is composed of primary care physicians who notify varicella cases on a compulsory basis. From 1995 to 2012, varicella cases were correlated to temperature, humidity, rainfall, water vapor pressure, atmospheric pressure, wind speed, and solar radiation using regression and time-series models. The influence of schooling was also analyzed. A total of 68,379 cases of varicella were notified during the study period. Cases occurred all year round, with a peak incidence in June. Varicella cases increased with the decrease in water vapor pressure and/or the increase of solar radiation, 3 and 4 weeks prior to reporting, respectively. An inverse association was also observed between varicella cases and school holidays. Using these variables, the best fitting autoregressive moving average with exogenous variables (ARMAX) model could predict 95 % of varicella cases. In conclusion, varicella in our region had a clear seasonality, which was mainly determined by solar radiation and water vapor pressure. PMID:25265908

Hervás, D; Hervás-Masip, J; Nicolau, A; Reina, J; Hervás, J A

2014-09-30

245

Mars atmospheric water vapor abundance: 1996-1997  

NASA Astrophysics Data System (ADS)

Measurements of martian atmospheric water vapor made throughout Ls = 18.0°-146.4° (October 3, 1996-July 12, 1997) show changes in Mars humidity on hourly, daily, and seasonal time scales. Because our observing program during the 1996-1997 Mars apparition did not include concomitant measurement of nearby CO 2 bands, high northern latitude data were corrected for dust and aerosol extinction assuming an optical depth of 0.8, consistent with ground-based and HST imaging of northern dust storms. All other measurements with airmass greater than 3.5 were corrected using a total optical depth of 0.5. Three dominant results from this data set are as follows: (1) pre- and post-opposition measurements made with the slit crossing many hours of local time on Mars' Earth-facing disk show a distinct diurnal pattern with highest abundances around and slightly after noon with low abundances in the late afternoon, (2) measurements of water vapor over the Mars Pathfinder landing site (Carl Sagan Memorial Station) on July 12, 1997, found 21 ppt ?m in the spatial sector centered near 19° latitude, 36° longitude while abundances around the site varied from as low as 6 to as high as 28 ppt ?m, and (3) water vapor abundance is patchy on hourly and daily time scales but follows the usual seasonal trends.

Sprague, A. L.; Hunten, D. M.; Doose, L. R.; Hill, R. E.

2003-05-01

246

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

247

Amorphous and crystalline aerosol particles interacting with water vapor - Part 1: Microstructure, phase transitions, hygroscopic growth and kinetic limitations  

Microsoft Academic Search

Interactions with water are crucial for the properties, transformation and climate effects of atmospheric aerosols. Here we outline characteristic features and differences in the interaction of amorphous and crystalline aerosol particles with water vapor. Using a hygroscopicity tandem differential mobility analyzer (H-TDMA), we performed hydration, dehydration and cyclic hydration&dehydration experiments with aerosol particles composed of levoglucosan, oxalic acid and ammonium

E. Mikhailov; S. Vlasenko; S. T. Martin; T. Koop; U. Pöschl

2009-01-01

248

Characterization of the TIP4PEw water model: Vapor pressure and boiling point  

Microsoft Academic Search

The liquid-vapor-phase equilibrium properties of the previously developed TIP4P-Ew water model have been studied using thermodynamic integration free-energy simulation techniques in the temperature range of 274-400 K. We stress that free-energy results from simulations need to be corrected in order to be compared to the experiment. This is due to the fact that the thermodynamic end states accessible through simulations

Hans W. Horn; William C. Swope; Jed W. Pitera

2005-01-01

249

Characterization of the TIP4PEw water model: Vapor pressure and boiling point  

Microsoft Academic Search

The liquid-vapor-phase equilibrium properties of the previously developed TIP4P-Ew water model have been studied using thermodynamic integration free-energy simulation techniques in the temperature range of 274–400 K. We stress that free-energy results from simulations need to be corrected in order to be compared to the experiment. This is due to the fact that the thermodynamic end states accessible through simulations

Hans W. Horn; William C. Swope; Jed W. Pitera

2005-01-01

250

Water Vapor, Cloud Liquid Water Paths, and Rain Rates over the Northern High Latitude Open Seas  

E-print Network

Water Vapor, Cloud Liquid Water Paths, and Rain Rates over the Northern High Latitude Open Seas-based Instrumentation: May 1-8 time series 35 GHz cloud radar ice cloud properties depolarization lidar-determined liquid cloud base Microwave radiometer-derived liquid water paths Near-surface T ~ -30 C, inversion

Zuidema, Paquita

251

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 such as cloud mask, atmos- pheric profiles, aerosol properties, total precipitable water, and cloud properties of land, ocean, and atmospheric properties. Twenty-six bands are used to derive atmospheric properties

Sheridan, Jennifer

252

Understanding the Sahelian water budget through the isotopic composition of water vapor and precipitation  

Microsoft Academic Search

The goal of this paper is to investigate the added value of water isotopic measurements to estimate the relative influence of large-scale dynamics, convection, and land surface recycling on the Sahelian water budget. To this aim, we use isotope data in the lower tropospheric water vapor measured by the SCIAMACHY and TES satellite instruments and in situ precipitation data from

Camille Risi; Sandrine Bony; Françoise Vimeux; Christian Frankenberg; David Noone; John Worden

2010-01-01

253

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

254

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

255

Water vapor heterogeneity related to tropopause folds over the North Atlantic revealed by airborne water vapor DIAL  

Microsoft Academic Search

Abstract 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 regularly develop along

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

256

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

257

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.

Makarieva, Anastassia M

2010-01-01

258

Correlation for the Vapor Pressure of Heavy Water From the Triple Point to the Critical Point  

E-print Network

Correlation for the Vapor Pressure of Heavy Water From the Triple Point to the Critical Point Allan the vapor pressure of heavy water (D2O) from its triple point to its critical point. This work takes temperatures are converted from ITS-90 to IPTS-68 before the vapor pressure is com- puted. The new formulation

Magee, Joseph W.

259

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

260

Water Vapor Profiling From CoSSIR Radiometric Measurements  

NASA Technical Reports Server (NTRS)

Previous millimeter-wave radiometry for water vapor profiling, by either airborne or satellite sensors, has been limited to frequencies less than or equal to 183 GHz. The retrievals are generally limited to an altitude range of 0-10 km. The additional measurements at the frequencies of 380.2 plus or minus 0.8, 380.2 plus or minus 1.8, 380.2 plus or minus 3.3, and 380.2 plus or minus 6.2 GHz provided by the new airborne Compact Scanning Submillimeter-wave Imaging Radiometer (CoSSIR) can extend this profiling capability up to an altitude of about 15 km. Furthermore, the retrievals can be performed over both land and water surfaces in the tropics without much difficulty. These properties are demonstrated by recent CoSSIR measurements on board the NASA WB-57 aircraft during CR-AVE in January 2006. Retrievals of water vapor mixing ratio were performed at eight altitude levels of 1, 3, 5, 7, 9, 11, 13, and 15 km from CoSSIR data sets acquired at observational angles of 0 and 53.4 degrees, and the results were compared with other available measurements from the same aircraft and near-concurrent satellites. A comparison of the variations of mixing ratios retrieved from CoSSIR and those derived from the Meteorological Measurement System (MMS) in the aircraft vicinity, along the path of the transit flight on January 14, 2006, appears to show some connection, although the measurements were referring to different altitudes. A very good agreement was found between the collocated values of total precipitable water derived from the CoSSIR-retrieved water vapor profiles and those estimated from TMI (TRMM Microwave Imager)

Wang, J. R.; Chang, L. A.; Monosmith, B.; Zhang, Z.

2007-01-01

261

Numerical Analysis of coupled liquid water, water vapor and heat transport in a sandy loam soil  

NASA Astrophysics Data System (ADS)

Water vapor transport could be significant in arid areas such as southern New Mexico. Temporal soil moisture variations in unsaturated soils due to temperature gradients are characterized by the water vapor transport in the surface soil layer as liquid water movement could be very small especially when surface soil moisture is low. Numerical model Hydrus-1D was applied to investigate non-isothermal liquid and vapor flow closely coupled with the heat transport in a furrow-irrigated onion field located at Leyendecker Plant Science Research Center, Las Cruces. TDR and temperature sensors were installed to continuously monitor diurnal soil moisture and temperature variations in sandy loam onion beds at 5, 10, 20, and 50 cm depths during the entire growing season. Meteorological data were obtained from PSRC weather station. Hydrus-1D simulated soil moisture and temperature favorably contrasted against measured data at different depths. Simulations indicated that both liquid and vapor fluxes contributed to the water transport near surface. Liquid flux dominated the water movement during an irrigation event, while contribution of vapor flux increased with increasing soil drying. Vapor flux decreased from 5 cm to 25 cm depth, indicating that water vapor flux is much higher in the layer near soil surface. Both diffusive and dispersive transports are responsible for the vapor flux in the near-surface dry zone, while convective liquid flux was the main transport mechanism in the near-surface wet lower zone. In near-surface wet zone, diffusive flux decreased and changed from upward to downward flux.

Shukla, M. K.; Deb, S.; Sharma, P.

2009-12-01

262

Lidar vertical profiling of water vapor and aerosols in the Great Lakes Region: A tool for understanding lower atmospheric dynamics  

NASA Astrophysics Data System (ADS)

Results of a recently developed water vapor Raman lidar instrument at Environment Canada's Center for Atmospheric Research Experiments (CARE) are shown for selected days of summer and winter seasons. The basic components of the Raman water vapor lidar consist of a 30 Hz, Q-switched Nd:YAG high-powered laser utilizing the third harmonic (355 nm), beam steering optics, a 0.76 m Cassegrain telescope and three detection channels to simultaneously observe the vertical profiles of aerosols, water vapor, and nitrogen from near ground up to 9.5 km. By manipulating the inelastic backscattering lidar signals from the Raman nitrogen channel (386.7 nm) and Raman water vapor channel (407.5 nm), vertical profiles of water vapor mixing ratio (WVMR) are deduced, calibrated, and compared against WVMR profiles obtained from coincident and collocated radiosonde profiles. The average standard deviation, in the water vapor mixing ratio, is estimated to be less than 10% between the sonde and lidar measurements. In addition, comparisons between simultaneous WVMR profiles and aerosol profiles obtained from a simple aerosol backscatter lidar, also located at the CARE facility, provide insight into the complex dynamic mixing of the lower atmosphere and their subsequent impact on climate and air quality.

Al-Basheer, Watheq; Strawbridge, Kevin B.

2015-02-01

263

CO2 and Water Vapor Exchange across Leaf Cuticle (Epidermis) at Various Water Potentials.  

PubMed Central

Cuticular properties affect the gas exchange of leaves, but little is known about how much CO2 and water vapor cross the cuticular barrier or whether low water potentials affect the process. Therefore, we measured the cuticular conductances for CO2 and water vapor in grape (Vitis vinifera L.) leaves having various water potentials. The lower leaf surface was sealed to force all gas exchange through the upper surface, which was stoma-free. In this condition both gases passed through the cuticle, and the CO2 conductance could be directly determined from the internal mole fraction of CO2 near the compensation point, the external mole fraction of CO2, and the CO2 flux. The cuticle allowed small amounts of CO2 and water vapor to pass through, indicating that gas exchange occurs in grape leaves no matter how tightly the stomata are closed. However, the CO2 conductance was only 5.7% of that for water vapor. This discrimination against CO2 markedly affected calculations of the mole fraction of CO2 in leaves as stomatal apertures decreased. When the leaf dehydrated, the cuticular conductance to water vapor decreased, and transpiration and assimilation diminished. This dehydration effect was largest when turgor decreased, which suggests that cuticular gas exchange may have been influenced by epidermal stretching. PMID:12223698

Boyer, J. S.; Wong, S. C.; Farquhar, G. D.

1997-01-01

264

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

265

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

266

Cassini/CIRS Observations of Water Vapor in Titan's Stratosphere  

NASA Technical Reports Server (NTRS)

The Composite Infrared Spectrometer (CIRS) on the Cassini spacecraft has obtained spectra of Titan during most of the 44 flybys of the Cassini prime mission. Water vapor on Titan was first detected using whole-disk observations from the Infrared Space Observatory (Coustenis et al 1998, Astron. Astrophys. 336, L85-L89). CIRS data permlt the retrieval of the latitudinal variation of water on Titan and some limited information on its vertical profile. Emission lines of H2O on Titan are very weak in the CIRS data. Thus, large spectral averages as well as improvements in calibration are necessary to detect water vapor. Water abundances were retrieved in nadir spectra at 55 South, the Equator, and at 19 North. Limb spectra of the Equator were also modeled to constrain the vertical distribution of water. Stratospheric temperatures in the 0.5 - 4.0 mbar range were obtained by inverting spectra of CH4 in the v4 band centered at 1304/cm. The temperature in the lower stratosphere (4 - 20 mbar) was derived from fitting pure rotation lines of CH4 between 80 and 160/cm. The origin of H2O and CO2 is believed to be from the ablation of micrometeorites containing water ice, followed by photochemistry. This external source of water originates either within the Saturn system or from the interplanetary medium. Recently, Horst et al (J. Geophys. Res. 2008, in press) developed a photochemical model of Titan in which there are two external sources of oxygen. Oxygen ions (probably from Enceladus) precipitate into Titan's atmosphere to form CO at very high altitudes (1100 km). Water ice ablation at lower altitudes (700 km) forms H2O and subsequent chemistry produces CO2. CIRS measurements of CO, CO2, and now of H2O will provide valuable constraints to these photochemical models and - improve our understanding of oxygen chemistry on Titan.

Bjoraker, Gordon L.; Achterberg, R. K.; Anderson, C. M.; Samuelson, R. E.; Carlson, R. C.; Jennings, D. E.

2008-01-01

267

Twenty-Four-Hour Raman Lidar Water Vapor Measurements During the Atmospheric Radiation Measurement Program's 1996 and 1997 Water Vapor Intensive Observation Periods  

Microsoft Academic Search

Prior to the Atmospheric Radiation Measurement program's first water vapor intensive observation period (WVIOP) at the Cloud and Radiation Testbed site near Lamont, Oklahoma, an automated 24-h Raman lidar was delivered to the site. This instrument, which makes high-resolution measurements of water vapor both spatially and temporally, is capable of making these measurements with no operator interaction (other than initial

David D. Turner; JE M. Goldsmith

1999-01-01

268

Precipitable water vapor on the Tibetan Plateau estimated by GPS, water vapor radiometer, radiosonde, and numerical weather prediction analysis and its impact on the radiation budget  

Microsoft Academic Search

Precipitable water vapor amounts (PW) determined by Global Positioning System (GPS), radiosonde and operational numerical weather prediction (NWP) system analysis at three stations (Naqu, Gaize, and Deqin) on the Tibetan Plateau are compared. PW measured by water vapor radiometer at Naqu and a low-elevation site, Xian, is used for calibration. The results show that the PW determined by NWP analysis

J. Liu; Z. Sun; H. Liang; X. Xu; P. Wu

2005-01-01

269

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

270

Characterization of the TIP4P-Ew water model: Vapor pressure and boiling point  

NASA Astrophysics Data System (ADS)

The liquid-vapor-phase equilibrium properties of the previously developed TIP4P-Ew water model have been studied using thermodynamic integration free-energy simulation techniques in the temperature range of 274-400K. We stress that free-energy results from simulations need to be corrected in order to be compared to the experiment. This is due to the fact that the thermodynamic end states accessible through simulations correspond to fictitious substances (classical rigid liquids and classical rigid ideal gases) while experiments operate on real substances (liquids and real gases, with quantum effects). After applying analytical corrections the vapor pressure curve obtained from simulated free-energy changes is in excellent agreement with the experimental vapor pressure curve. The boiling point of TIP4P-Ew water under ambient pressure is found to be at 370.3±1.9K, about 7K higher than the boiling point of TIP4P water (363.7±5.1K; from simulations that employ finite range treatment of electrostatic and Lennard-Jones interactions). This is in contrast to the approximately +15K by which the temperature of the density maximum and the melting temperature of TIP4P-Ew are shifted relative to TIP4P, indicating that the temperature range over which the liquid phase of TIP4P-Ew is stable is narrower than that of TIP4P and resembles more that of real water. The quality of the vapor pressure results highlights the success of TIP4P-Ew in describing the energetic and entropic aspects of intermolecular interactions in liquid water.

Horn, Hans W.; Swope, William C.; Pitera, Jed W.

2005-11-01

271

Characterization of the TIP4P-Ew water model: vapor pressure and boiling point.  

PubMed

The liquid-vapor-phase equilibrium properties of the previously developed TIP4P-Ew water model have been studied using thermodynamic integration free-energy simulation techniques in the temperature range of 274-400 K. We stress that free-energy results from simulations need to be corrected in order to be compared to the experiment. This is due to the fact that the thermodynamic end states accessible through simulations correspond to fictitious substances (classical rigid liquids and classical rigid ideal gases) while experiments operate on real substances (liquids and real gases, with quantum effects). After applying analytical corrections the vapor pressure curve obtained from simulated free-energy changes is in excellent agreement with the experimental vapor pressure curve. The boiling point of TIP4P-Ew water under ambient pressure is found to be at 370.3+/-1.9 K, about 7 K higher than the boiling point of TIP4P water (363.7+/-5.1 K; from simulations that employ finite range treatment of electrostatic and Lennard-Jones interactions). This is in contrast to the approximately +15 K by which the temperature of the density maximum and the melting temperature of TIP4P-Ew are shifted relative to TIP4P, indicating that the temperature range over which the liquid phase of TIP4P-Ew is stable is narrower than that of TIP4P and resembles more that of real water. The quality of the vapor pressure results highlights the success of TIP4P-Ew in describing the energetic and entropic aspects of intermolecular interactions in liquid water. PMID:16321097

Horn, Hans W; Swope, William C; Pitera, Jed W

2005-11-15

272

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

273

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

274

Storm Signatures in GPS-derived Estimates of Atmospheric Water Vapor  

NASA Astrophysics Data System (ADS)

Southern Alberta experiences unique weather patterns owing to its proximity to the Rocky Mountains. Fast-developing storms that originate in the foothills can take forecasters and Albertans by surprise. Water is an important part of any weather prediction study because it has a high latent heat and thus by tracking water, heat movement is tracked as well. Traditional methods of collecting data on atmospheric water vapor (such as radiosonde) do not offer the spatial and temporal resolution necessary for high-resolution analysis of storm systems. In order to fully understand weather patterns, continuous water vapor data sets with high spatial resolution are needed. GPS has been widely used for positioning and navigation purposes. Among other error sources, the troposphere causes a delay in the GPS signal received at the Earth through a hydrostatic component and a wet component. Once other sources of error are mitigated, the positioning problem can be inverted such that the total neutral atmospheric delay is solved for. From the total delay, the wet component can be isolated by applying a hydrostatic delay model. The hydrostatic delay can be determined with millimeter level accuracy using precise surface pressure measurements. By using data from a regional network of GPS stations, spatial models of the water vapor can be derived in a local area. In the summer of 2003, a network of eleven GPS stations was deployed in southern Alberta for precise positioning and atmospheric water vapor determination. The spacing between stations was designed to be approximately 50 km in order to give optimal results for mesoscale numerical weather prediction. The focus of this project is a case study of the July 20, 2003 thunderstorm that was observed in the Calgary area during the Alberta - GPS Atmospheric Moisture Evaluation (A-GAME) data collection campaign. Data were collected during this campaign in a collaborative effort between the Geomatics Engineering Department at the University of Calgary, the Meteorological Service of Canada (MSC), and Weather Modification Inc. Hourly estimates of slant wet delays were derived at each station in the southern Alberta GPS network using Bernese version 4.2. These results were input in a tomographic model, and water vapor fields were estimated and analysed to determine spatial variations and temporal evolution of the storm event. Validation of GPS water vapor estimates was conducted through comparisons with radiometer data at University of Calgary. Weather Modification Inc. also provided a complementary radar data set which was used to identify precipitation and correlate storm evolution with the GPS results.

Hoyle, V.; Nicholson, N.; Skone, S.

2004-05-01

275

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

276

Observations of water vapor by ground-based microwave radiometers and Raman lidar  

NASA Technical Reports Server (NTRS)

In November to December 1991, a substantial number of remote sensors and in situ instruments were operated together in Coffeyville, Kansas, during the climate experiment First ISCCP Regional Experiment Phase 2 (FIRE 2). Includede in the suite of instruments were (1) the NOAA Environmental Technology Laboratory (ETL) three-channel microwave radiometer, (2) the NASA GSFC Raman lidar, (3) ETL radio acoustic sounding system (RASS), and (4) frequent, research-quality radiosondes. The Raman lidar operated only at night and the focus of this portion of the experiment concentrated on clear conditions. The lidar data, together with frequent radiosondes and measurements of temperature profiles (every 15 min) by RASS allowed profiles of temperature and absolute humidity to be estimated every minute. We compared 20 min measurements of brightness temperature (T(sub b) with calculations of T(sub b) that were based on the Liebe and Layton (1987) and Liebe et al. (1993) microwave propagation models, as well as the Waters (1976) model. The comparisons showed the best agreement at 20.6 GHz with the Waters model, with the Liebe et al. (1993) model being best at 31.65 GHz. The results at 90 GHz gave about equal success with the Liebe and Layton (1987) and Liebe et al. (1993) models. Comparisons of precipitable water vapor derived independently from the two instruments also showed excellent agreement, even for averages as short as 2 min. The rms difference between Raman and radiometric determinations of precipitable water vapor was 0.03 cm which is roughly 2%. The experiments clearly demonstrate the potential of simultaneous operation of radiometers and Raman lidars for fundamental physical studies of water vapor.

Han, Yong; Snider, J. B.; Westwater, E. R.; Melfi, S. H.; Ferrare, R. A.

1994-01-01

277

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

278

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

279

A comparison of observed (HALOE) and modeled (CCM2) methane and stratospheric water vapor  

NASA Technical Reports Server (NTRS)

Recent measurements (21 September-15 October 1992) of methane and water vapor by the Halogen Occultation Experiment (HALOE) on the Upper Atmosphere Research Satellite (UARS) are compared with model results for the same season from a troposphere-middle atmosphere version of the National Center for Atmospheric Research (NCAR) Community Climate Model (CCM2). Several important features of the two constituent fields are well reproduced by the CCM2, despite the use of simplified methane photochemistry in the CCM2 and some notable differences between the model's zonal mean circulation and climatology. Observed features simulated by the model include the following: 1) subsidence over a deep layer in the Southern Hemisphere polar vortex; 2) widespread dehydration in the polar vortex; and 3) existence of a region of low water vapor mixing ratios extending from the Antarctic into the Northern Hemisphere tropics, which suggests that Antarctic dehydration contributes to midlatitude and tropical dryness in the stratosphere.

Mote, Philip W.; Holton, James R.; Russell, James M., III; Boville, Byron A.

1993-01-01

280

Adsorption of water vapor on modified methacrylate polymeric sorbents  

SciTech Connect

Adsorption of water vapor on methacrylate copolymers and terpolymers was studied. An increase in the content of the cross-linking agent gives rise to increase in the limiting adsorption of water vapor at the saturation pressure (a{sub s}) and to decrease in the concentration of primary adsorption centers. Modification of the initial copolymer containing 60% of 2,3-epoxypropyl methacrylate (EPMA) monomer and 40% of cross-linking agent, ethylene dimethacrylate, with diethylenetriamine (DETA) results in an increase in the a{sub s} value, while modification with C{sub 12} and C{sub 18} alkyl, benzyl, and phenyl groups gives rise to decrease in the a{sub s} values for the copolymeric sorbents. The concentration of primary adsorption centers (a{sub m}) increases considerably on modification of the copolymer with DETA and C{sub 12} groups and decreases markedly on modification with benzyl and phenyl groups. For terpolymers, containing EPMA and styrene, an increase in the styrene/EPMA ratio reduces the a{sub s}, and a{sub m} values. The copolymer modified with DETA groups possesses the most hydrophilic properties, while the copolymer modified with benzyl group exhibits the most hydrophobic properties. The mechanism of adsorption of water molecules on the polymers is discussed.

Platonova, N.P.; Tataurova, O.G.; Vartapetyan, R.Sh. [Institute of Physical Chemistry, Moscow (Russian Federation)] [and others

1995-12-31

281

Coherent DIAL measurement of range-resolved water vapor concentration  

NASA Astrophysics Data System (ADS)

A pulsed coherent CO2 lidar was employed to measure water vapor profiles by the differential absorption lidar (DIAL) technique. Measurements were obtained to ranges of 10 km along horizontal paths and 6 km when the lidar beam angle was elevated. Comparisons with nearby rawinsonde soundings showed fairly good agreement, although a tendency for the lidar to overestimate relative to the sonde was observed. Uncertainties in the individual measurements were attributable primarily to speckle, quantum noise, and atmospheric nonstationarities. The DIAL data set was also used to obtain radial wind velocity measurements at ranges beyond the maximum range of the concentration measurement.

Hardesty, R. M.

1984-08-01

282

An alexandrite regenerative amplifier for water vapor and temperature measurements  

NASA Technical Reports Server (NTRS)

The Differential Absorption Lidar (DIAL) technique is a powerful method for determining meteorological parameters, but it requires high quality of the laser source: high energy, very narrow bandwidth, high wavelength stability, and spectral purity. Although many efforts have been made to improve the lasers in view of these aspects, a satisfactory solution has not been demonstrated up to now. We describe a regenerative amplifier, using a Ti:sapphire laser as master oscillator and an alexandrite laser as slave amplifier, which is expected to meet the requirements for water vapor concentration and temperature measurements.

Thro, P.-Y.; Boesenberg, J.; Wulfmeyer, V.

1992-01-01

283

Water Vapor Winds and Their Application to Climate Change Studies  

NASA Technical Reports Server (NTRS)

The retrieval of satellite-derived winds and moisture from geostationary water vapor imagery has matured to the point where it may be applied to better understanding longer term climate changes that were previously not possible using conventional measurements or model analysis in data-sparse regions. In this paper, upper-tropospheric circulation features and moisture transport covering ENSO periods are presented and discussed. Precursors and other detectable interannual climate change signals are analyzed and compared to model diagnosed features. Estimates of winds and humidity over data-rich regions are used to show the robustness of the data and its value over regions that have previously eluded measurement.

Jedlovec, Gary J.; Lerner, Jeffrey A.

2000-01-01

284

Water vapor measurement system in global atmospheric sampling program, appendix  

NASA Technical Reports Server (NTRS)

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

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

1982-01-01

285

Broadband water vapor transmission functions for atmospheric IR flux computations  

NASA Technical Reports Server (NTRS)

Transmission functions associated with water vapor molecular line and e-type absorption in the IR spectra regions are presented in the form of simple analytical functions and small tables, from which atmospheric IR fluxes and cooling rates can be easily computed. For typical clear atmospheres ranging from the tropics to the subarctic region, the difference with respect to line-by-line calculations is less than 0.15 C/day in the cooling rate and approximately equal to or less than 1 percent in fluxes.

Chou, M.-D.

1984-01-01

286

Raman-shifted dye laser for water vapor DIAL measurements  

NASA Technical Reports Server (NTRS)

For improved DIAL measurements of water vapor in the upper troposphere or lower stratosphere, narrowband (about 0.03/cm) laser radiation at 720- and 940-nm wavelengths was generated by stimulated Raman scattering (SRS), using the narrow linewidth (about 0.02/cm) output of a Nd:YAG-pumped dye laser. For a hydrogen pressure of 350 psi, the first Stokes conversion efficiencies to 940 nm were 20 percent and 35 percent, when using a conventional and waveguide Raman cell, respectively. The linewidth of the first Stokes line at high cell pressures, and the inferred collisional broadening coefficients, agree well with those previously measured in spontaneous Raman scattering.

Grossmann, B. E.; Singh, U. N.; Cotnoir, L. J.; Wilkerson, T. D.; Higdon, N. S.; Browell, E. V.

1987-01-01

287

Carbon dioxide and water vapor high temperature electrolysis  

NASA Technical Reports Server (NTRS)

The design, fabrication, breadboard testing, and the data base obtained for solid oxide electrolysis systems that have applications for planetary manned missions and habitats are reviewed. The breadboard tested contains sixteen tubular cells in a closely packed bundle for the electrolysis of carbon dioxide and water vapor. The discussion covers energy requirements, volume, weight, and operational characteristics related to the measurement of the reactant and product gas compositions, temperature distribution along the electrolyzer tubular cells and through the bundle, and thermal energy losses. The reliability of individual cell performance in the bundle configuration is assessed.

Isenberg, Arnold O.; Verostko, Charles E.

1989-01-01

288

Nd:Glass-Raman laser for water vapor dial  

NASA Technical Reports Server (NTRS)

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

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

1986-01-01

289

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

290

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

291

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

NASA Technical Reports Server (NTRS)

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 deg N, 5 deg 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 percent at the lower altitude and falls to 20 percent at 25 km. For water vapor the time sequences are 4 min or 8 min long and the accuracy is better than 10 percent in the lower troposphere.

Flamant, P. H.; Pelon, J.; Lefrere, J.; Megie, G.; Cahen, C.

1982-01-01

292

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 concentrations in different regions throughout the nebula. Gravitational settling will lead to concentrations of solids that are a few hundred times greater than that of the canonical solar nebula (14). Turbulent

Utrecht, Universiteit

293

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

294

Measurement of Low Amounts of Precipitable Water Vapor Using Ground-Based Millimeterwave Radiometry  

NASA Technical Reports Server (NTRS)

Extremely dry conditions characterized by amounts of precipitable water vapor (PWV) as as 1-2 mm commonly occur in high-latitude regions during the winter months. While such atmospheres carry only a few percent of the latent heat energy compared to tropical atmospheres, the effects of low vapor amounts on the polar radiation budget - both directly through modulation of longwave radiation and indirectly through the formation of clouds - are considerable. Accurate measurements of precipitable water vapor (PWV) during such dry conditions are needed to improve polar radiation models for use in understanding and predicting change in the climatically sensitive polar regions. To this end, the strong water vapor absorption at 183.310 GHz provides a unique means of measuring low amounts of PWV. Weighting function analysis, forward model calculations based upon a 7-year radiosonde dataset, and retrieval simulations consistently predict that radiometric measurements made using several millimeter-wavelength (MMW) channels near the 183 GHz line, together with established microwave (MW) measurements at the 22.235 GHz water vapor line and -3 1 GHz atmospheric absorption window can be used to determine within 5% uncertainty the full range of PWV expected in the Arctic. This unique collective capability stands in spite of accuracy limitations stemming from uncertainties due to the sensitivity of the vertical distribution of temperature and water vapor at MMW channels. In this study the potential of MMW radiometry using the 183 GHz line for measuring low amounts of PWV is demonstrated both theoretically and experimentally. The study uses data obtained during March 1999 as part of an experiment conducted at the Department of Energy s Cloud and Radiation Testbed (CART) near Barrow, Alaska. Several radiometers from both NOAA and NASA were deployed during the experiment to provide the first combined MMW and MW ground-based data set during dry arctic conditions. Single-channel retrievals of PWV were performed using the MW and MMW data. Discrepancies in the retrieved values were found to be consistent with differences observed between measured brightness temperatures (TBs) and forward-modeled TBs based on concurrent radiosonde profiles. These discrepancies are greater than can be explained by measurement error alone and are attributed to absorption model uncertainty. We discuss here the measurements, retrieval technique, and line model discrepancies along with difficulties and potential of MMW/MW PWV measurement.

Racette, Paul E.; Westwater, Ed R.; Han, Yong; Gasiewski, Albin J.; Klein, Marian; Cimini, Domenico; Jones, David C.; Manning, WIll; Kim, Edward J.; Wang, James R.

2003-01-01

295

On the relationship between water vapor over the oceans and sea surface temperature  

NASA Technical Reports Server (NTRS)

Monthly mean precipitable water data obtained from passive microwave radiometry were correlated with the National Meteorological Center (NMC) blended sea surface temperature data. It is shown that the monthly mean water vapor content of the atmosphere above the oceans can generally be prescribed from the sea surface temperature with a standard deviation of 0.36 g/sq cm. The form of the relationship between precipitable water and sea surface temperature in the range T(sub s) greater than 18 C also resembles that predicted from simple arguments based on the Clausius-Clapeyron relationship. The annual cycle of the globally integrated mass of Scanning Multichannel Microwave Radiometer (SMMR) water vapor is shown to differ from analyses of other water vapor data in both phase and amplitude and these differences point to a significant influence of the continents on water vapor. Regional scale analyses of water vapor demonstrate that monthly averaged water vapor data, when contrasted with the bulk sea surface temperature relationship developed in this study, reflect various known characteristics of the time mean large-scale circulation over the oceans. A water vapor parameter is introduced to highlight the effects of large-scale motion on atmospheric water vapor. Based on the magnitude of this parameter, it is shown that the effects of large-scale flow on precipitable water vapor are regionally dependent, but for the most part, the influence of circulation is generally less than about + or - 20 percent of the seasonal mean.

Stephens, Graeme L.

1989-01-01

296

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

297

Observations of water vapor by ground-based microwave radiometers and Raman lidar  

SciTech Connect

In November to December 1991, a substantial number of remote sensors and in situ instruments were operated together in Coffeyville, Kansas, during the climate experiment FIRE II. Included in the suite of instruments were (1) the NOAA Environmental Technology Laboratory (ETL) three-channel microwave radiometer, (2) the NASA GSFC Raman lidar, (3) ETL radio acoustic sounding system (RASS), and (4) frequent, research-quality radiosondes. The Raman lidar operated only at night and the focus of this portion of the experiment concentrated on clear conditions. The lidar data, together with frequent radiosondes and measurements of temperature profiles (every 15 min) by RASS allowed profiles of temperature and absolute humidity to be estimated every minute. The authors compared 2-min measurements of brightness temperature (T{sub b}) with calculations of T{sub b} that were based on the Liebe and Layton, and Liebe et al. microwave propagation models, as well as the Waters model. The comparisons showed the best agreement at 20.6 GHz with the Waters model, with the Liebe et al. model being best at 31.65 GHz. The results at 90 GHz gave about equal success with the Liebe and Layton, and Liebe et al. models. Comparisons of precipitable water vapor derived independently from the two instruments also showed excellent agreement, even for averages as short as 2 min. The rms difference between Raman and radiometric determinations of precipitable water vapor was 0.03 cm which is roughly 2%. The experiments clearly demonstrate the potentisdal of simultaneous operation of radiometers and Raman lidars for fundamental physical studies of water vapor. 31 refs., 5 figs., 5 tabs.

Han, Y.; Snider, J.B.; Westwater, E.R. [NOAA Environmental Research Lab., Boulder, CO (United States)] [NOAA Environmental Research Lab., Boulder, CO (United States); Melfi, S.H. [NASA Goddard Space Flight Center, Greenbelt, MD (United States)] [NASA Goddard Space Flight Center, Greenbelt, MD (United States); Ferrare, R.A. [Hughes-STX Corp., Lanham, MD (United States)] [Hughes-STX Corp., Lanham, MD (United States)

1994-09-20

298

Preprototype vapor compression distillation subsystem. [recovering potable water from wastewater  

NASA Technical Reports Server (NTRS)

A three-person capacity preprototype vapor compression distillation subsystem for recovering potable water from wastewater aboard spacecraft was designed, assembled, and tested. The major components of the subsystem are: (1) a distillation unit which includes a compressor, centrifuge, central shaft, and outer shell; (2) a purge pump; (3) a liquids pump; (4) a post-treat cartridge; (5) a recycle/filter tank; (6) an evaporator high liquid level sensor; and (7) the product water conductivity monitor. A computer based control monitor instrumentation carries out operating mode change sequences, monitors and displays subsystem parameters, maintains intramode controls, and stores and displays fault detection information. The mechanical hardware occupies 0.467 m3, requires 171 W of electrical power, and has a dry weight of 143 kg. The subsystem recovers potable water at a rate of 1.59 kg/hr, which is equivalent to a duty cycle of approximately 30% for a crew of three. The product water has no foul taste or odor. Continued development of the subsystem is recommended for reclaiming water for human consumption as well as for flash evaporator heat rejection, urinal flushing, washing, and other on-board water requirements.

Ellis, G. S.; Wynveen, R. A.; Schubert, F. H.

1979-01-01

299

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

300

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

SciTech Connect

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

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

1996-04-01

301

A Study of Hygropause Using Water Vapor Data From SAGE II (Version 6.1)  

Microsoft Academic Search

A characteristic feature of the water vapor profile near the tropopause is the so called hygropause or the minimum in the water vapor mixing ratio which is an important element in the stratosphere-troposphere exchange processes. A statistical study of the hygropause has been carried out using 12 years (1985-1990, 1994-1999) of water vapor data in the latitude range 30N-30S from

J. Kar; G. Taha; C. R. Trepte; L. W. Thomason; J. M. Zawodny

2002-01-01

302

Linkages Among Water Vapor Flows, Food Production, and Terrestrial Ecosystem Services  

Microsoft Academic Search

Global freshwater assessments have not addressed the linkages among water vapor flows, agricultural food production, and terrestrial ecosystem services. We perform the first bottom-up estimate of continental water vapor flows, subdivided into the major terrestrial biomes, and arrive at a total continental water vapor flow of 70,000 km3\\/yr (ranging from 56,000 to 84,000 km3\\/yr). Of this flow, 90% is attributed

Johan Rockström; Line Gordon; Carl Folke; Malin Falkenmark; Maria Engwall

2009-01-01

303

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

Microsoft Academic Search

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

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

1994-01-01

304

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 ...

2014-12-09

305

TES/Aura L2 Water Vapor (H2O) Limb (TL2H2OLS)  

TES/Aura L2 Water Vapor (H2O) Limb (TL2H2OLS) 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 ...

2015-01-30

306

Water vapor microwave continuum absorption: A comparison of measurements and models  

Microsoft Academic Search

Measurements, made in different laboratories, of absorption by water vapor in microwave windows are compared with models for the water vapor continuum. A reanalysis of some of these measurements leads to the conclusion that the laboratory data are best represented by a combination of Liebe's (1987) millimeter-wave propagation model (MPM) for the foreign-broadened component of the water continuum and the

Philip W. Rosenkranz

1998-01-01

307

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

308

The Use of Water Vapor for Detecting Environments that Lead to Convectively Produced Heavy Precipitation and Flash Floods  

NASA Technical Reports Server (NTRS)

This Tech Report summarizes years of study and experiences on using GOES Water vapor (6.7 micron and precipitable water) and Special Sensor Microwave Imager (SSM/1) from the Defense Meteorological Satellite Program (DMSP) derived Precipitable Water (PNAI) for detecting environments favorable for convectively produced flash floods. An emphasis is on the moisture. upper air flow, and equivalent potential temperature (Theta(sub e)) patterns that lead to devastating flood events. The 15 minute 6.7 micron water vapor imagery is essential for tracking middle to upper tropospheric disturbances that produce upward vertical motion and initiate flash flood producing systems. Water vapor imagery at 6.7 micron is also used to detect surges of upper level moisture (called tropical water vapor plumes) that have been associated with extremely heavy rainfall. Since the water vapor readily depicts lifting mechanisms and upper level moisture, water vapor imagery is often an excellent source of data for recognizing patterns of heavy precipitation and flash floods. In order to analyze the depth of the moisture, the PW aspects of the troposphere must be measured. The collocation (or nearby location) of high values ofP\\V and instability are antecedent conditions prior to the flash flood or heavy rainfall events. Knowledge of PW magnitudes have been used as thresholds for impending flash flood events, PW trends are essential in flash flood prediction. Conceptual models and water vapor products are used to study some of the characteristics of convective systems that occurred over the United States of America (USA) during the summer of 1997 and the 1997-1998 El Nino. P\\V plumes were associated with most of the \\vest coast heavy precipitation events examined during the winter season of 1997 - 1998, In another study, conducted during the summer season of 1997. results showed that the collocation of water vapor (6.7 micron) and P\\N' plumes possessed higher correlations with predicted rainfall amounts than when PW plumes occurred by themselves (i.e.. without the presence of 6.7 micron water vapor plumes). Satellite Analysis Branch (SAB) meteorologists use the 6.7 micron water and P\\V products for their QPE's (interactive Flash Flood Analyzer (IFFA) and Auto-Estimator precipitation estimates), Outlooks, and heavy precipitation briefings with the Hydrometeorological Prediction Center/National Center for Environmental Prediction.

Scofield, Rod; Vicente, Gilberto; Hodges, Mike

2000-01-01

309

Comparison of lidar water vapor measurements using Raman scatter at 266 nm and 532 nm  

SciTech Connect

The performance of the Lidar Atmospheric Profile Sensor (LAPS) instrument for measurements of water vapor in the lower troposphere has been investigated. LAPS is an automated lidar system that measures water vapor from the vibrational Raman backscatter in the visible and in the ultraviolet wavelength range. The authors present a comparison of water vapor profiles measured with the lidar and balloon sondes as well as measured with the two lidar channels. With the UV channels it is possible to infer ozone profiles in the boundary layer. Data are presented that reveal the high variability of the water vapor in the boundary layer.

Balsiger, F.; Philbrick, C.R. [Pennsylvania State Univ., State College, PA (United States). Applied Research Lab.

1996-12-31

310

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

311

High-resolution atmospheric water vapor measurements with a scanning differential absorption lidar  

NASA Astrophysics Data System (ADS)

The scanning differential absorption lidar (DIAL) of the University of Hohenheim (UHOH) is presented. The UHOH DIAL is equipped with an injection-seeded frequency-stabilized high-power Ti:sapphire laser operated at 818 nm with a repetition rate of 250 Hz. A scanning transceiver unit with a 80 cm primary mirror receives the atmospheric backscatter signals. The system is capable of water vapor measurements with temporal resolutions of a few seconds and a range resolution between 30 and 300 m at daytime. It allows to investigate surface-vegetation-atmosphere exchange processes with high resolution. In this paper, we present the design of the instrument and illustrate its performance with recent water vapor measurements taken in Stuttgart-Hohenheim and in the frame of the HD(CP)2 Observational Prototype Experiment (HOPE). HOPE was located near research center Jülich, in western Germany, in spring 2013 as part of the project "High Definition of Clouds and Precipitation for advancing Climate Prediction" (HD(CP)2). Scanning measurements reveal the 3-dimensional structures of the water vapor field. The influence of uncertainties within the calculation of the absorption cross-section at wavelengths around 818 nm for the WV retrieval is discussed. Radiosonde intercomparisons show a very small bias between the instruments of only (-0.04 ± 0.11) g m-3 or (-1.0 ± 2.3) % in the height range of 0.5 to 3 km.

Späth, F.; Behrendt, A.; Muppa, S. K.; Metzendorf, S.; Riede, A.; Wulfmeyer, V.

2014-11-01

312

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

313

Nuclear quantum effects affect bond orientation of water at the water-vapor interface.  

PubMed

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 H(2)O and D(2)O 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. PMID:23368135

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

2012-11-30

314

Correlation Study of Water Vapor and Aerosol Distributions in Troposphere Using Scanning Raman Lidar  

NASA Astrophysics Data System (ADS)

Aiming at the study of water vapor and aerosol distributions in the lower atmosphere from the Otlica observatory, Slovenia (45.93°N, 13.91°E, elevation 945 m above sea level), we have built a new Raman lidar in parallel to the existing Mie lidar. The new system is oriented towards the Adriatic coast with a fixed azimuth angle of 235.1° and shares the transmitter (tripled Nd:YAG pulsed laser at 355 nm with pulse energy of 100 mJ and repetition rate of 20 Hz) and mechanical support with scanning functionality in zenith angle with the Mie lidar. The receiver part of the Raman lidar employs custom optics using a low f-number aspheric lens, designed to maximize the coupling of lidar returns collected by a parabolic mirror with a diameter of 800 mm and focal length of 410 mm and the 1000 ?m core multi-mode optical fiber used to transport the light to the polychromator for spectral analysis. In the polychromator, 5-nm bandwidth interference filters combined with dichroic beam splitters were used to separate the vibrational Raman signals of nitrogen and water wapor molecules. The three return signals were detected by photo-multiplier tubes and sampled by transient recorders in photon-counting mode. System functionality was assessed in a number of preliminary experiments, where water vapor concentrations were calibrated using radiosonde data. During the nights of 24-25 August 2011 a series of measurements of water vapor and aerosol distributions along the lidar line of sight were performed at various elevation angles. In the vertical measurements, two layers with larger water vapor content were visible at altitudes of 1.5 km and 4.0 km with relative humidity in both cases exceeding 75%. Aerosol extinction decreased linearly between the altitudes of 2 km and 4.5 km, with aerosol layers appearing at 4.0 km, 4.7 km and 5.6 km. In horizontal measurements, the water vapor mixing ratio and the relative humidity were found to be almost constant in the range of 1.5 km to 4.5 km with a sudden drop in close range (at 0.7 km), which corresponds to the variation in the terrain configuration along the line of sight. Between 2.5 km and 5.0 km the atmospheric extinction was also found to be constant with values of about 0.15 km-1. The measurements at an inclination of 25° showed linear decrease of water vapor concentration between the ranges of 1.5 km and 5.0 km with a number of indistinct peaks, while a linear increase of aerosol extinction was found in the same range with several aerosol layers between the altitudes of 2.2 km and 2.8 km. The correlation between water vapor and aerosol distributions was investigated by comparing the aerosol extinction to the water vapor mixing ratio. As no correlation was found, we conclude that the aerosols detected in the study region were predominantly non-hygroscopic.

Gao, F.; Stanic, S.; Bergant, K.; He, T.-Y.

2012-04-01

315

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

316

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

317

Effects of surface area and volume on the rate of isotopic exchange between water and water vapor  

SciTech Connect

The effects of surface area and volume on the rate of isotopic exchange between water and water vapor were quantified by allowing beakers containing waters with differing D, {sup 18}O, and tritium contents to equilibrate under controlled conditions in a closed system. Over a 2-month period the waters shifted by as much as 80{per_thousand} in {delta}D, 13{per_thousand} in {delta}{sup 18}O, and 57,000 tritium unit (TU), sometimes in opposite directions (either toward being more enriched or more depleted) depending upon initial compositions of the juxtaposed waters. Over time the concentrations of the stable and radioactive isotopes approach a common value, which in an ideal closed system represents the mean composition on a volumetric basis. The exchange rate is represented by dR{sub X}/dt={minus}(R{sub X}{minus}R{sub M})ks{sub x}/v{sub x} where R{sub X} represents the actual isotopic ratio of the water at time t, R{sub M} is equal to {alpha}{sub eg}*R{sub v} and represents the isotopic ratio of the water that would at any instant be in equilibrium with ambient vapor with an isotopic ratio of R{sub v}, and s{sub X}, and v{sub X} refer to the surface area and volume of the water, respectively. In these 20{degrees}C experiments the constant k ranged from 0.12 to 0.18 cm/d and was identical for D/H, T/H, and {sup 18}O/{sup 16}O exchange for a given set of conditions. In the case of identical surface areas and volumes the composition of the waters may change, but the vapor to which the waters respond remains the same during the exchange process. In the case of differing surface areas, or differing volumes, the composition of the vapor and R{sub M} will both change. In any case, after complete exchange, all waters will attain the same equilibrium isotopic ratio. 16 refs., 9 figs., 2 tabs.

Ingraham, N.L. [Univ. of Nevada System, Las Vegas, NV (United States); Criss, R.E. [Univ. of California, Davis, CA (United States)

1993-11-20

318

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

319

DMSP SSM/T-2 microwave water vapor profiler  

NASA Astrophysics Data System (ADS)

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

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

1993-08-01

320

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

321

Geographic Effects on Precipitation, Water Vapor and Temperature  

NSDL National Science Digital Library

There are many factors that affect an areaâs climate. By understanding these factors, someone could predict the average temperature, temperature range, and precipitation patterns of an area. They could also predict the type of vegetation likely to grow in an area based on these atmospheric conditions. In this activity, students will work in groups of three. Each group will be assigned one of six sets of cities. Each group will be responsible for comparing and contrasting the temperature, precipitation, and water vapor for the two cities in their set. At the end of the activity, students will present their findings to the rest of the class and determine whether or not the two locations have similar or different climatic conditions.

322

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

323

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

NASA Technical Reports Server (NTRS)

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

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

2006-01-01

324

The role of water vapor in climate. A strategic research plan for the proposed GEWEX water vapor project (GVaP)  

NASA Technical Reports Server (NTRS)

The proposed GEWEX Water Vapor Project (GVaP) addresses fundamental deficiencies in the present understanding of moist atmospheric processes and the role of water vapor in the global hydrologic cycle and climate. Inadequate knowledge of the distribution of atmospheric water vapor and its transport is a major impediment to progress in achieving a fuller understanding of various hydrologic processes and a capability for reliable assessment of potential climatic change on global and regional scales. GVap will promote significant improvements in knowledge of atmospheric water vapor and moist processes as well as in present capabilities to model these processes on global and regional scales. GVaP complements a number of ongoing and planned programs focused on various aspects of the hydrologic cycle. The goal of GVaP is to improve understanding of the role of water vapor in meteorological, hydrological, and climatological processes through improved knowledge of water vapor and its variability on all scales. A detailed description of the GVaP is presented.

Starr, D. OC. (editor); Melfi, S. Harvey (editor)

1991-01-01

325

Water, Vapor, and Salt Dynamics in a Hot Repository  

SciTech Connect

The purpose of this paper is to report the results of a new model study examining the high temperature nuclear waste disposal concept at Yucca Mountain using MULTIFLUX, an integrated in-drift- and mountain-scale thermal-hydrologic model. The results show that a large amount of vapor flow into the drift is expected during the period of above-boiling temperatures. This phenomenon makes the emplacement drift a water/moisture attractor during the above-boiling temperature operation. The evaporation of the percolation water into the drift gives rise to salt accumulation in the rock wall, especially in the crown of the drift for about 1500 years in the example. The deposited salts over the drift footprint, almost entirely present in the fractures, may enter the drift either by rock fall or by water drippage. During the high temperature operation mode, the barometric pressure variation creates fluctuating relative humidity in the emplacement drift with a time period of approximately 10 days. Potentially wet and dry conditions and condensation on salt-laden drift wall sections may adversely affect the storage environment. Salt accumulations during the above-boiling temperature operation must be sufficiently addressed to fully understand the waste package environment during the thermal period. Until the questions are resolved, a below-boiling repository design is favored where the Alloy-22 will be less susceptible to localized corrosion. (authors)

Bahrami, Davood; Danko, George [Department of Mining Engineering, University of Nevada, Reno, 1664 N. Virginia St., Reno, NV, 89557 (United States); Walton, John [Department of Civil Engineering, University of Texas at El Paso, 500 W. University, El Paso, TX, 79968 (United States)

2007-07-01

326

Electron density dropout near Enceladus in the context of water-vapor and water-ice  

E-print Network

: Farrell, W. M., W. S. Kurth, D. A. Gurnett, R. E. Johnson, M. L. Kaiser, J.-E. Wahlund, and J. H. Waite Jr W. S. Kurth,2 D. A. Gurnett,2 R. E. Johnson,3 M. L. Kaiser,1 J.-E. Wahlund,4 and J. H. Waite Jr.5Electron density dropout near Enceladus in the context of water-vapor and water-ice W. M. Farrell,1

Johnson, Robert E.

327

Application of improved technology to a preprototype vapor compression distillation /VCD/ water recovery subsystem  

NASA Technical Reports Server (NTRS)

Vapor compression distillation (VCD) is considered the most efficient water recovery process for spacecraft application. This paper reports on a preprototype VCD which has undergone the most extensive operational and component development testing of any VCD subsystem to date. The component development effort was primarily aimed at eliminating corrosion and the need for lubrication, upgrading electronics, and substituting nonmetallics in key rotating components. The VCD evolution is documented by test results on specific design and/or materials changes. Innovations worthy of further investigation and additional testing are summarized for future VCD subsystem development reference. Conclusions on experience gained are presented.

Johnson, K. L.; Reysa, R. P.; Fricks, D. H.

1981-01-01

328

Stratospheric water vapor measurements during CHEOPS-3. [CHemistry of Ozone in the Polar Stratosphere  

SciTech Connect

During January 1990, in situ stratospheric water vapor measurements were performed over the Arctic during the CHEOPS experiment at Kiruna. The instrument used is a balloon-borne frost-point hygrometer. Results of two flights are shown: one of the flights showed thermal structure indicative of cooling induced by orographic forcing and favorable to PSC formation. Mixing ratio were the same for the two flights, 4-5 ppmv between 12 and 22 km. However, above 22 km, an increase in mixing ratio to 7.5 ppmv is observed. Because this increase is much higher than at mid-latitudes, the authors examine it in detail.

Ovarlez, J. (Ecole Polytechnique, 91, Palaiseau (France))

1991-04-01

329

A water vapor Raman lidar as part of the Swiss meteorology service  

Microsoft Academic Search

Vertical water vapor profiles with high time resolution are necessary for improved numerical weather prediction (NWP). Meteorological services rely, in part, on NWP models for short to mid-term weather forecasting. Typically vertical water vapor profiles are acquired from twice a day radiosonde observations which have time resolution insufficient to resolve rapidly changing meteorological phenomena. New operational instruments with near real-time

T. Dinoev; Y. Arshinov; S. Bobrovnikov; P. Ristori; B. Calpini; H. van den Bergh; M. B. Parlange; V. Simeonov

2009-01-01

330

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

Microsoft Academic Search

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

Michael Drew Obland

2007-01-01

331

Development of a Water Vapor Tomography System Using Low Cost L1 GPS Receivers  

Microsoft Academic Search

A system of low cost Global Positioning System (GPS) stations is being developed to measure the three- dimensional (3-D) structure of tropospheric water vapor over a small ground network. The concept is to deploy 20 GPS stations in a network spanning 10 km to 20 km. For each of the 20 stations, we will measure the integrated water vapor from

J. Braun; C. Rocken; C. Meertens; R. Ware

332

Alexandrite laser characterization and airborne lidar developments for water vapor DIAL measurements  

NASA Technical Reports Server (NTRS)

The spectral characteristics of an Alexandrite laser used for making water vapor DIAL measurements have been evaluated. The optical servo-system used to lock the laser wavelength on a water vapor absorption line is described. A brief description of the DIAL system is given and the data obtained with this lidar during flight tests in March 1990 are also presented.

Ponsardin, P.; Higdon, N. S.; Grossmann, B. E.; Browell, E. V.

1991-01-01

333

Optimization of band-pass filtering parameters of a Raman lidar detecting atmospheric water vapor  

Microsoft Academic Search

It is very important for daytime Raman lidar measurement of water vapor to determine the parameters of a band-pass filter, which are pertinent to the lidar signal to noise ratio (SNR). The simulated annealing (SA) algorithm method has an advantage in finding the extremum of a certain cost function. In this paper, the Raman spectrum of water vapor is simulated

Kai-Fa Cao; Shun-Xing Hu; Ying-jian Wang

2012-01-01

334

Microwave Radiometer Networks for Measurement of the Spatio-Temporal Variability of Water Vapor  

Microsoft Academic Search

Tropospheric water vapor plays a key role in the prediction of convective storm initiation, precipitation and extreme weather events. Conventionally, water vapor profiles are derived from dewpoint and temperature measurements using instrumented weather balloons, including radiosondes. These balloons take approximately one hour to measure from surface to tropopause, and transmitter-sensor packages cannot be reused. Such in-situ measurements provide profiles with

S. C. Reising; F. Iturbide-Sanchez; S. Padmanabhan

2006-01-01

335

Isotopic Variability in Surface Water Vapor and Precipitation in the Upper Midwest, USA  

Microsoft Academic Search

The isotopic composition of surface water vapor and precipitation provides important information about the moisture source characteristics and subsequent transport processes and phase changes in the atmosphere. The objective of this research is to investigate the characteristics of delta18O, deltaD, and deuterium excess (d) in surface water vapor and precipitation in Rosemount, MN, a continental site characterized by hot, humid

N. M. Schultz; T. J. Griffis; J. M. Baker; X. Lee; M. Erickson; X. Zhang; W. Xiao; N. Hu

2010-01-01

336

A Two-Line Absorption Instrument for Scramjet Temperature and Water Vapor Concentration Measurement in HYPULSE  

NASA Technical Reports Server (NTRS)

A three beam water vapor sensor system has been modified to provide for near simultaneous temperature measurement. The system employs a tunable diode laser to scan spectral line of water vapor. The application to measurements in a scramjet combustor environment of a shock tunnel facility is discussed. This report presents and discusses die initial calibration of the measurement system.

Tsai, C. Y.

1998-01-01

337

High Temperature Corrosion of Silicon Carbide and Silicon Nitride in Water Vapor  

NASA Technical Reports Server (NTRS)

Silicon carbide (SiC) and silicon nitride (Si3N4) are proposed for applications in high temperature combustion environments containing water vapor. Both SiC and Si3N4 react with water vapor to form a silica (SiO2) scale. It is therefore important to understand the durability of SiC, Si3N4 and SiO2 in water vapor. Thermogravimetric analyses, furnace exposures and burner rig results were obtained for these materials in water vapor at temperatures between 1100 and 1450 C and water vapor partial pressures ranging from 0.1 to 3.1 atm. First, the oxidation of SiC and Si3N4 in water vapor is considered. The parabolic kinetic rate law, rate dependence on water vapor partial pressure, and oxidation mechanism are discussed. Second, the volatilization of silica to form Si(OH)4(g) is examined. Mass spectrometric results, the linear kinetic rate law and a volatilization model based on diffusion through a gas boundary layer are discussed. Finally, the combined oxidation and volatilization reactions, which occur when SiC or Si3N4 are exposed in a water vapor-containing environment, are presented. Both experimental evidence and a model for the paralinear kinetic rate law are shown for these simultaneous oxidation and volatilization reactions.

Opila, E. J.; Robinson, Raymond C.; Cuy, Michael D.; Gray, Hugh R. (Technical Monitor)

2002-01-01

338

Tracking Water Vapor in the Winter High Arctic using the Microwave Humidity Sounder  

Microsoft Academic Search

The cold and dry conditions during the darkness of the winter High Arctic have been a challenge for the retrieval of tropospheric water vapor amounts from satellites. Water vapor remains the most important greenhouse gas even in these dry conditions and so its variability has a direct bearing on the radiative forcing at the surface. The presence of the surface-based

T. J. Duck; G. B. Lesins; J. R. Drummond

2010-01-01

339

Models of the atmospheric water vapor budget for the Texas HIPLEX area: by Steven Francis Williams.  

E-print Network

be completely underst!. nd sn envirorm&ental w. '-er bu&iget des. . ribes the transports, distributio. . s, and supplies of water. vapor a sociated with various forr! of convective activity. Observatrorrs of diff "rences 'n the water vapor budget fr&r various...

Williams, Steven Francis

2012-06-07

340

On water vapor, surface temperature and the greenhouse effect---a statistical analysis of  

E-print Network

On water vapor, surface temperature and the greenhouse effect---a statistical analysis of tropical the response of the atmosphere to surface warming. To take into account the compensating drying effects tropospheric water­vapor con­ tent. The effect on the tropical mean Outgoing Long­Wave Radiation is also

Tung, Ka-Kit

341

A meta-analysis of water vapor deuterium-excess in the midlatitude atmospheric surface layer  

E-print Network

.1029/2011GB004246. 1. Introduction [2] Water vapor is the most important atmospheric greenhouse gas, contributing to approximately two-thirds of the Earth's greenhouse effect [Mitchell, 1989; IntergovernmentalA meta-analysis of water vapor deuterium-excess in the midlatitude atmospheric surface layer Lisa R

Minnesota, University of

342

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

343

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

344

A Fixed Point Charge Model for Water Optimized to the Vapor-Liquid Coexistence Properties  

E-print Network

A Fixed Point Charge Model for Water Optimized to the Vapor-Liquid Coexistence Properties Jeffrey R@ipst.umd.edu #12;1 Abstract A new fixed-point charge potential model for water has been developed, targeting the accurate prediction of the vapor-liquid coexistence properties over a broad temperature range. The model

345

Profiling the atmospheric water vapor content using a GPS-Meteorology network  

E-print Network

Profiling the atmospheric water vapor content using a GPS-Meteorology network Jayson Maldonado forecasting by use of a GPS-Meteorology network. The first step in flood forecasting is precipitation/CLOBK which processes the required slant water vapor measurements from a network of GPS-Meteorological

Mountziaris, T. J.

346

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

347

The systematic behavior of water vapor estimates using four years of GPS observations  

Microsoft Academic Search

The authors have used four years of Global Positioning System (GPS) data to study the amount of integrated water vapor (IWV) in the atmosphere. They find that the presence of certain radomes at some sites highly affects the water vapor estimates at other sites. These effects are eliminated by using a technique in which data from each station are processed

T. Ragne Emardson; Jan Johansson; Gunnar Elgered

2000-01-01

348

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

349

Synergetic Use of GPS Water Vapor and Meteosat Images for Synoptic Weather Forecasting  

Microsoft Academic Search

The use of integrated water vapor (IWV) measurements from a ground-based global positioning system (GPS) for nowcasting is described for a cold front that passed the Netherlands during 16 and 17 May 2000. Meteosat water vapor (WV) and infrared (IR) channel measurements are incorporated to analyze this weather situation. A cloud band with embedded cumulonimbus clouds (Cb) preceded the cold

Siebren de Haan; Sylvia Barlag; Henk Klein Baltink; Frans Debie; Hans van der Marel

2004-01-01

350

Relating soil specific surface area, water film thickness, and water vapor adsorption  

NASA Astrophysics Data System (ADS)

of soil specific surface area (SSA) and dry-end water vapor adsorption are important for porous media characterization and for prediction of water and vapor fluxes in arid environments. The objective of the presented study was to model water adsorption, film thickness, and SSA based on the t-curve theory originally developed for N2 adsorption. Data from 21 source soils with clay contents ranging from 0.6 to 52.2% were used to estimate specific surface area based on water retention, a t-curve type method, the linear prediction method, and a simplified monolayer method. The water retention and the t-curve methods were found to be mathematically analogous and were among the most accurate with regard to correlation coefficient (r = 0.97) and root-mean-square error (RMSE = 11.36 × 103 m2/kg) when compared to measurements obtained with the standard ethylene glycol monoethyl ether (EGME) method. The corrected t-curve method significantly overestimated SSA when compared to EGME data. Comparison of all considered methods with N2-BET (BET) measurements disclosed lower correlation coefficients. For soil studies, the vapor adsorption in conjunction with the t-curve or water retention methods should be preferred for SSA estimation as they show much higher correlation with soil clay content and EGME measurements.

Leão, Tairone Paiva; Tuller, Markus

2014-10-01

351

Global Distribution of Water Vapor in the Martian Atmosphere: Results from TES  

NASA Astrophysics Data System (ADS)

Atmospheric water vapor is an integral part of the water cycle on Mars, just as on Earth, and is the one that we can study most easily. Following methods laid out by Smith ( Geophys. Res. Lett. v28, n22, 2001), this study used data from the TES instrument onboard the MGS orbiter to calculate a brightness temperature ratio of water vapor to the background atmosphere, a ratio that changes in quadratic proportion to the column depth of water vapor present. Multiple spectral bands from 200 to 400 cm-1 were used in order to avoid most interference from dust and water ice in the Martian atmosphere. Smith looked primarily at annual and interannual variability in longitude-averaged vapor; this study expands the viewpoint to examine in detail the global distribution of water vapor over a single Martian year. Due to elevation-related effects in the column depth calculation, data were mapped in both raw form, and adjusted for elevation differences. It was found that water vapor is not evenly distributed at a given latitude; rather, there are significant longitudinal variations. The most notable variations occur at equatorial latitudes, from 30°N to 30°S, but the effects are not restricted to these latitudes. Although there is no good evidence of extremely localized (order of a few km) sources of water vapor, there is evidence quite suggestive of large-scale regolith exchange, particularly in but not restricted to the southern hemisphere, poleward of 45°S, and possibly in Arabia Terra. There are also patterns to suggest that there is a net loss of water vapor to the north, in contradiction to some MCGM results; however, this will require further study. Overall, elevation and seasonal air temperature/wind changes exhibit the strongest controls over water vapor column depth; thermal inertia has a lesser role. Albedo does not appear to independently influence the water vapor distribution.

Krelove, K.; Christensen, P.; Smith, M.

2005-12-01

352

Ultra-narrowband optical fiber Bragg grating filters for water vapor lidar atmospheric measurements  

Microsoft Academic Search

An ultra narrowband, high transmission fiber Bragg grating optical filter at 946 nm is presented for water vapor lidar measurements. The filter and water line have the same bandwidths, significantly reducing optical background in lidar receivers.

R. J. De Young; L. B. Vann; S. Mihailov; R. Walker; D. Grobnic

2004-01-01

353

Application of an automatic cloud tracking technique to Meteosat water vapor and infrared observations  

NASA Technical Reports Server (NTRS)

The automatic cloud tracking system was applied to METEOSAT 6.7 micrometers water vapor measurements to learn whether the system can track the motions of water vapor patterns. Data for the midlatitudes, subtropics, and tropics were selected from a sequence of METEOSAT pictures for 25 April 1978. Trackable features in the water vapor patterns were identified using a clustering technique and the features were tracked by two different methods. In flat (low contrast) water vapor fields, the automatic motion computations were not reliable, but in areas where the water vapor fields contained small scale structure (such as in the vicinity of active weather phenomena) the computations were successful. Cloud motions were computed using METEOSAT infrared observations (including tropical convective systems and midlatitude jet stream cirrus).

Endlich, R. M.; Wolf, D. E.

1980-01-01

354

In Situ Tuff Water Migration/Heater Experiment. Final report  

SciTech Connect

This report summarizes the results of the In Situ Tuff Water Migration/Heater Experiment operated in the welded portion of the Grouse Canyon Member of the Belted Range Tuff in U12g-tunnel (G-Tunnel) on the Nevada Test Site (NTS). The experiment was located approximately 400 m below the surface and 200 m above the water table in nearly saturated rock. The experiment was designed to provide an initial assessment of the thermally induced behavior of the potentially large volumes of water ({similar_to}25 vol % in this case) available in saturated or nearly saturated tuffaceous rocks. Instruments in the water collection cavities, including water depth gages, pH probes, humidity gages, and pressure transducers measured some properties of the collected water. Other holes in the array were instrumented to measure temperature profiles, thermally induced stress, and one provided a test bed for a continuously operating laser interferometer for measuring thermally induced rock displacements. Initial analysis of the water generation rate data in the heater hole, assuming a one-dimensional evaporation front/vapor diffusion model, provided good qualitative agreement. The results of chemical analyses of water samples supports the notion of mass transport by vapor diffusion in the heater hole but not in the water migration holes. Rock temperatures in the heater hole exceeded 240{sup 0}C. The stress meters measured maximum radial and circumferential thermal stresses of 8.62 and 4.83 MPa respectively - approximately 40% of the pretest predicted values. The experiment with the laser interferometer was a failure. The results of the water migration experiment indicate that the pore water in these rocks was highly mobile, probably by a vapor diffusion/condensation process.

Johnstone, J.K.; Hadley, G.R.; Waymire, D.R.

1985-03-01

355

Measurements of daytime and upper tropospheric water vapor profiles by Raman lidar  

SciTech Connect

One of the most important atmospheric constituents needed for climate and meteorological studies is water vapor. Water vapor plays an important role in driving atmospheric circulations through latent heat release and in determining the earth`s radiation budget, both through its radiative effects (water vapor is the major greenhouse gas) and cloud formation. The vertical distribution of water vapor is particularly important because it not only determines convective stability but radiative effects are also strongly altitude dependent. At present, considerable controversy exists over the nature of the vertical redistribution of water vapor in a changing climate, and particularly the distribution of water vapor in the upper troposphere. Understanding upper tropospheric moistening processes such as deep convection are therefore of prime importance in addressing the water vapor feedback question. A powerful, proven technique for the continuous measurement of nighttime water vapor profiles (in clear skies or up to the lowest cloud level) with high spatial and temporal resolution is Raman lidar. As part of the U.S. Department of Energy`s (DOE) Atmospheric Radiation Measurement (ARM) program, a high performance dual field-of-view (fov), narrowband Raman lidar system capable of both daytime and nighttime operation has been developed. In this paper, the Sandia Raman lidar system is discussed along with its application to two problems of current interest: daytime tropospheric water vapor profile measurements and upper tropospheric water vapor. We present recent measurements of upper tropospheric moisture made at the DOE Cloud and Radiation Testbed site (CART) in Oklahoma. Recent daytime measurements are also presented.

Bisson, S.E.; Goldsmith, J.E.M.

1995-03-01

356

Airborne Sunphotometry of Aerosol Optical Depth and Columnar Water Vapor During ACE-Asia  

NASA Technical Reports Server (NTRS)

During the Intensive Field Campaign (IFC) of the Aerosol Characterization Experiment - Asia (ACE-Asia), March-May 2001, the 6-channel NASA Ames Airborne Tracking Sunphotometer (AATS-6) operated during 15 of the 19 research flights aboard the NCAR C- 130, while its 14-channel counterpart (AATS- 14) was flown successfully on all 18 research flights of a Twin Otter aircraft operated by the Center for Interdisciplinary Remotely Piloted Aircraft Studies (CIRPAS), Monterey, CA. ACE-Asia was the fourth in a series of aerosol characterization experiments and focused on aerosol outflow from the Asian continent to the Pacific basin. Each ACE was designed to integrate suborbital and satellite measurements and models so as to reduce the uncertainty in calculations of the climate forcing due to aerosols. The Ames Airborne Tracking Sunphotometers measured solar beam transmission at 6 (380-1021 nm, AATS-6) and 14 wavelengths (353-1558 nm, AATS-14) respectively, yielding aerosol optical depth (AOD) spectra and column water vapor (CWV). Vertical differentiation in profiles yielded aerosol extinction and water vapor concentration. The wavelength dependence of AOD and extinction indicates that supermicron dust was often a major component of the aerosol. Frequently this dust-containing aerosol extended to high altitudes. For example, in data flights analyzed to date 34 +/- 13% of full-column AOD(525 nm) was above 3 km. In contrast, only 10 +/- 4% of CWV was above 3 km. In this paper, we will show first sunphotometer-derived results regarding the spatial variation of AOD and CWV, as well as the vertical distribution of aerosol extinction and water vapor concentration. Preliminary comparison studies between our AOD/aerosol extinction data and results from: (1) extinction products derived using in situ measurements and (2) AOD retrievals using the Multi-angle Imaging Spectro-Radiometer (MISR) aboard the TERRA satellite will also be presented.

Redemann, Jens; Schmid, B.; Russell, P. B.; Livingston, J. M.; Eilers, J. A.; Ramirez, S. A.; Kahn, R.; Hipskind, R. Stephen (Technical Monitor)

2001-01-01

357

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

358

Water-mediated ion–ion interactions are enhanced at the water vapor–liquid interface  

PubMed Central

There is overwhelming evidence that ions are present near the vapor–liquid interface of aqueous salt solutions. Charged groups can also be driven to interfaces by attaching them to hydrophobic moieties. Despite their importance in many self-assembly phenomena, how ion–ion interactions are affected by interfaces is not understood. We use molecular simulations to show that the effective forces between small ions change character dramatically near the water vapor–liquid interface. Specifically, the water-mediated attraction between oppositely charged ions is enhanced relative to that in bulk water. Further, the repulsion between like-charged ions is weaker than that expected from a continuum dielectric description and can even become attractive as the ions are drawn to the vapor side. We show that thermodynamics of ion association are governed by a delicate balance of ion hydration, interfacial tension, and restriction of capillary fluctuations at the interface, leading to nonintuitive phenomena, such as water-mediated like charge attraction. “Sticky” electrostatic interactions may have important consequences on biomolecular structure, assembly, and aggregation at soft liquid interfaces. We demonstrate this by studying an interfacially active model peptide that changes its structure from ?-helical to a hairpin-turn–like one in response to charging of its ends. PMID:24889634

Venkateshwaran, Vasudevan; Vembanur, Srivathsan; Garde, Shekhar

2014-01-01

359

The application of the high-speed photography in the experiments of boiling liquid expanding vapor explosions  

NASA Astrophysics Data System (ADS)

The liquefied-petroleum gas tank in some failure situations may release its contents, and then a series of hazards with different degrees of severity may occur. The most dangerous accident is the boiling liquid expanding vapor explosion (BLEVE). In this paper, a small-scale experiment was established to experimentally investigate the possible processes that could lead to a BLEVE. As there is some danger in using LPG in the experiments, water was used as the test fluid. The change of pressure and temperature was measured during the experiment. The ejection of the vapor and the sequent two-phase flow were recorded by a high-speed video camera. It was observed that two pressure peaks result after the pressure is released. The vapor was first ejected at a high speed; there was a sudden pressure drop which made the liquid superheated. The superheated liquid then boiled violently causing the liquid contents to swell, and also, the vapor pressure in the tank increased rapidly. The second pressure peak was possibly due to the swell of this two-phase flow which was likely to violently impact the wall of the tank with high speed. The whole evolution of the two-phase flow was recorded through photos captured by the high-speed video camera, and the "two step" BLEVE process was confirmed.

Chen, Sining; Sun, Jinhua; Chen, Dongliang

2007-01-01

360

LASE Measurements of Water Vapor, Aerosol, and Cloud Distributions in Saharan Air Layers and Tropical Disturbances  

NASA Technical Reports Server (NTRS)

LASE (Lidar Atmospheric Sensing Experiment) onboard the NASA DC-8 was used to measure high resolution profiles of water vapor and aerosols, and cloud distributions in 14 flights over the eastern Atlantic region during the NAMMA (NASA African Monsoon Multidisciplinary Analyses) field experiment, which was conducted from August 15 to September 12, 2006. These measurements were made in conjunction with flights designed to study African Easterly Waves (AEW), Tropical Disturbances (TD), and Saharan Aerosol Layers (SALs) as well as flights performed in clear air and convective regions. As a consequence of their unique radiative properties and dynamics, SAL layers have a significant influence in the development of organized convection associated with TD. Interactions of the SAL with tropical air during early stages of the development of TD were observed. These LASE measurements represent the first simultaneous water vapor and aerosol lidar measurements to study the SAL and its impact on TDs and hurricanes. Seven AEWs were studied and four of these evolved into tropical storms and three did not. Three out of the four tropical storms evolved into hurricanes.

Ismail, Syed; Ferrare, Richard; Browell, Edward; Kooi, Susan; Notari, Anthony; Butler, Carolyn; Burton, Sharon; Fenn, Marta; Krishnamurti, T. N.; Dunion, Jason; Heymsfield, Gerry; Anderson, Bruce

2008-01-01

361

Spatial distribution of deuterium in atmospheric water vapor: Diagnosing sources and the mixing of atmospheric moisture  

NASA Astrophysics Data System (ADS)

We measured the stable isotopic composition of hydrogen (? D) within atmospheric water vapor collected simultaneously at six sites in the vicinity of a lake (Lake Kasumigaura, Eastern Japan) to determine its spatial distribution characteristics and thereby diagnose sources and mixing of atmospheric moisture. The measured spatial distribution of ? D showed no relation to distance from the lake, although it showed a correlation with the distribution of the water-vapor mixing ratio Q. For two of the three sampling days, we found a simple two-component (i.e., water vapor transpiring from local land surfaces and pre-existing vapor in the background atmosphere) mixing line in a Keeling plot (i.e., ? - 1/ Q diagram). On a third day, however, contributions from lake evaporation were detected in addition to the above components. On this day, lake-derived vapor accounted for approximately 10-20% of atmospheric water vapor at the sites located leeward of the lake. The observed differences in mixing patterns among sampling days can be explained by a simple atmospheric moisture budget. Thus, it is likely that simultaneous isotopic measurements of atmospheric water vapor at multiple locations with aid of Keeling plot are capable of giving us useful information in diagnosing the sources and mixing pattern of the vapor.

Yamanaka, Tsutomu; Shimizu, Ryosuke

2007-07-01

362

A two-channel, tunable diode laser-based hygrometer for measurement of water vapor and cirrus cloud ice water content in the upper troposphere and lower stratosphere  

NASA Astrophysics Data System (ADS)

The recently developed NOAA Water instrument is a two-channel, closed-path, tunable diode laser absorption spectrometer designed for the measurement of upper troposphere/lower stratosphere water vapor and enhanced total water (vapor + inertially enhanced condensed phase) from the NASA Global Hawk unmanned aircraft system (UAS) or other high-altitude research aircraft. The instrument utilizes wavelength-modulated spectroscopy with second harmonic detection near 2694 nm to achieve high precision with a 79 cm double-pass optical path. The detection cells are operated under constant temperature, pressure, and flow conditions to maintain a constant sensitivity to H2O independent of the ambient sampling environment. An onboard calibration system is used to perform periodic in situ calibrations to verify the stability of the instrument sensitivity during flight. For the water vapor channel, ambient air is sampled perpendicular to the flow past the aircraft in order to reject cloud particles, while the total water channel uses a heated, forward-facing inlet to sample both water vapor and cloud particles. The total water inlet operates subisokinetically, thereby inertially enhancing cloud particle number in the sample flow and affording increased cloud water content sensitivity. The NOAA Water instrument was flown for the first time during the second deployment of the Airborne Tropical TRopopause EXperiment (ATTREX) in February-March 2013 on the NASA Global Hawk UAS. The instrument demonstrated a typical in-flight precision (1 s, 1?) of better than 0.17 parts per million (ppm, 10-6 mol mol-1), with an overall H2O vapor measurement uncertainty of 5% ± 0.23 ppm. The inertial enhancement for cirrus cloud particle sampling under ATTREX flight conditions ranged from 33 to 48 for ice particles larger than 8 ?m in diameter, depending primarily on aircraft altitude. The resulting ice water content detection limit (2?) was 0.023-0.013 ppm, corresponding to approximately 2 ?g m-3, with an estimated overall uncertainty of 20%.

Thornberry, T. D.; Rollins, A. W.; Gao, R. S.; Watts, L. A.; Ciciora, S. J.; McLaughlin, R. J.; Fahey, D. W.

2015-01-01

363

Cycling of gaseous elemental mercury: Importance of water vapor  

NASA Astrophysics Data System (ADS)

Gaseous elemental mercury is typically not thought of as a soluble compound, but its Henry’s law constant of 0.11 - 0.14 M atm-1 at 298K indicates enough water solubility that it must be considered in chemical cycling of Hg(0). We included mass transfer between the gaseous-aqueous phases and mercury aqueous reactions into our gas phase mercury chemical box model in order to better understand loss of Hg0 during nighttime. Mass transfer between the gaseous-aqueous phases was significantly influenced by water solubility of Hg(0) and the amount of liquid water content (LWC). The impact of water solubility of Hg(0) was examined through two sensitivity experiments; with and without aerosol chemistry. Ten hours of simulation showed that ~3.8 ppqv and ~11.5 ppqv of Hg(0) were decreased without and with aerosol chemistry respectively. The amount of Hg(0) lost indicated that aerosol uptake into its liquid water could be very important to mercury cycling compared to loss by dry deposition of Hg(0) alone. The sensitivity experiments showed also that Hg(aq) was increased to 9-102 ppqv with variable LWC ranging from 2exp(-12)-2exp(-10) after 10 hours of simulation. Finally, we conducted sensitivity experiments with consideration of dry deposition of speciated mercury. The sensitivity experiments indicated that dry deposition of particulate mercury (PHg) is critical to generate typical ambient levels of PHg compared to Hg0 and RGM. The loss of Hg(0) by aerosol uptake and dry deposition suggested that aerosol uptake of Hg(0) could play an important role in mercury cycling in the atmosphere.

Kim, S.; Talbot, R. W.; Mao, H.

2010-12-01

364

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

365

Climatology and Dynamics of Water Vapor: Three Years of Sounding with the Differential Absorption Lidar on Mt. Zugspitze  

Microsoft Academic Search

Water vapor is the the most important greenhouse gas and its vertical distribution plays a major role for the radiative balance. In particular in the upper troposphere the radiative transfer is very sensitive to small changes of the water-vapor concentration. At the same time the water-vapor distribution strongly depends on atmospheric dynamics and, thus, can serve as a good tracer

Hannes Vogelmann; Thomas Trickl

2010-01-01

366

ADVANCES IN ATMOSPHERIC SCIENCES, VOL. 24, NO. 3, 2007, 509526 Variational Assimilation of GPS Precipitable Water Vapor and  

E-print Network

weightings and the control of spurious gravity waves. Key words: GPS, precipitable water vapor, four Precipitable Water Vapor and Hourly Rainfall Observations for a Meso- Scale Heavy Precipitation Event During of the precipitable water vapor (PWV) from delayed signals transmitted by GPS satellites, which can be assimilated

367

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

368

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

369

The Use of GPS Measurements for Water Vapor Determination.  

NASA Astrophysics Data System (ADS)

A workshop on the use of Global Positioning System (GPS) measurements in weather and climate with emphasis on water vapor determination, was organized by the National Environmental Research Council's (NERC) Environmental Systems Science Centre (ESSC), at the University of Reading, Reading, United Kingdom, and took place there 29-31 August 2001.This paper gives a broad overview and general background of the use of GPS data for weather and climate. It outlines the objectives of the workshop and presents ongoing national, regional, and international activities both for ground-based and satellite-based systems. This includes work in the United States, China, and Japan, and different European efforts, including activities under European Community programs.Data assimilation of GPS data for weather prediction and climate is discussed as are ways in which to develop GPS-based systems to become an integrated part of the World Weather Watch. This includes ways of systematically using GPS data from the international geodetic network for climate monitoring purposes.

Bengtsson, Lennart; Robinson, Gary; Anthes, Rick; Aonashi, Kazumasa; Dodson, Alan; Elgered, Gunnar; Gendt, Gerd; Gurney, Robert; Jietai, Mao; Mitchell, Cathryn; Mlaki, Morrison; Rhodin, Andreas; Silvestrin, Pierluigi; Ware, Randolph; Watson, Robert; Wergen, Werner

2003-09-01

370

Electrode kinetics of a water vapor electrolysis cell  

NASA Technical Reports Server (NTRS)

The anodic electrochemical behavior of the water vapor electrolysis cell was investigated. A theoretical review of various aspects of cell overvoltage is presented with special emphasis on concentration overvoltage and activation overvoltage. Other sources of overvoltage are described. The experimental apparatus controlled and measured anode potential and cell current. Potentials between 1.10 and 2.60 V (vs NHE) and currents between 0.1 and 3000 mA were investigated. Different behavior was observed between the standard cell and the free electrolyte cell. The free electrolyte cell followed typical Tafel behavior (i.e. activation overvoltage) with Tafel slopes of about 0.15, and the exchange current densities of 10 to the minus 9th power A/sq cm, both in good agreement with literature values. The standard cell exhibitied this same Tafel behavior at lower current densities but deviated toward lower than expected current densities at higher potentials. This behavior and other results were examined to determine their origin.

Jacobs, G.

1974-01-01

371

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

372

Scale Invariance of Precipitable Water Vapor in the Arctic From Ground-Based Radiometric Measurements  

NASA Astrophysics Data System (ADS)

This study gives a first assessment of the usefulness of Millimeter-wave Radiometer (MIR) brightness temperature measurements for studying the scale invariance in atmospheric Precipitable Water Vapor (PWV) and Liquid Water Path (LWP) distributions in the Arctic. It is shown that MIR data display well defined scaling properties at frequencies close to 183.3 and 89 GHz during both clear-sky and cloudy conditions for horizontal scales between 350 m and 350 km. The turbulent variability of PWV and LWP, in the extremely dry arctic environment, is characterized using three mathematical techniques involving increasingly higher statistical moments. The first technique is the Detrended Fluctuation Analysis from which one can determine the existence of long-range correlations and the Hurst exponent H for the time series. Then, spectral analysis, that is a second order statistics and relies on the assumption of a Gaussian distribution, is performed on the time series data to explore scaling properties through the spectral exponent b. Lastly, a multiplicative cascade model is applied to millimeter-wave measurements to describe intermittency features characteristic of non-homogeneous turbulent fields. The results for LWP during cloudy days are in excellent agreement with previous studies conducted in different environmental conditions giving H = 0.33 and b = 1.61. PWV data during clear sky days have a slightly higher average Hurst exponent and spectral exponent (H=0.57, b = 1.89). Both PWV and LWP have similar intermittency parameter: C1 ~ 0.1 and C1 ~ 0.06 respectively. The analysis shows that intermittency is an important feature of arctic water vapor variability that can not be captured by a second order statistics such as spectral analysis. Therefore water vapor should not be regarded as a passive scalar subject to homogeneous turbulence. Instead, it should be treated as a randomly advected tracer that presents a multifractal (anomalous) scaling. In the present experiment the data could be well fitted using a universal log-Levy cascade generator. These experimental results can be used to validate theoretical models describing the transport of water vapor at higher latitudes.

Cadeddu, M.; Racette, P.; Wang, J.

2003-12-01

373

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

374

Water Vapor Permeability of the Advanced Crew Escape Suit  

NASA Technical Reports Server (NTRS)

Crew Exploration Vehicle (CEV) crewmembers are expected to return to earth wearing a suit similar to the current Advanced Crew Escape Suit (ACES). To ensure optimum cognitive performance, suited crewmembers must maintain their core body temperature within acceptable limits. There are currently several options for thermal maintenance in the post-landing phase. These include the current baseline, which uses an ammonia boiler, purge flow using oxygen in the suit, accessing sea water for liquid cooling garment (LCG) cooling and/or relying on the evaporative cooling capacity of the suit. These options vary significantly in mass, power, engineering and safety factors, with relying on the evaporative cooling capacity of the suit being the least difficult to implement. Data from previous studies indicates that the evaporative cooling capacity of the ACES was much higher than previously expected, but subsequent tests were performed for longer duration and higher metabolic rates to better define the water vapor permeability of the ACES. In these tests five subjects completed a series of tests performing low to moderate level exercise in order to control for a target metabolic rate while wearing the ACES in an environmentally controlled thermal chamber. Four different metabolic profiles at a constant temperature of 95 F and relative humidity of 50% were evaluated. These tests showed subjects were able to reject about twice as much heat in the permeable ACES as they were in an impermeable suit that had less thermal insulation. All of the heat rejection differential is attributed to the increased evaporation capability through the Gortex bladder of the suit.

Bue, Grant; Kuzneth, Larry; Gillis, David; Jones, Jeffery; Daniel, Brian; Gernhardt, Michael; Hamilton, Douglas

2009-01-01

375

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

376

Temporal changes in endmember abundances, liquid water and water vapor over vegetation at Jasper Ridge  

NASA Technical Reports Server (NTRS)

Imaging spectrometry offers a new way of deriving ecological information about vegetation communities from remote sensing. Applications include derivation of canopy chemistry, measurement of column atmospheric water vapor and liquid water, improved detectability of materials, more accurate estimation of green vegetation cover and discrimination of spectrally distinct green leaf, non-photosynthetic vegetation (NPV: litter, wood, bark, etc.) and shade spectra associated with different vegetation communities. Much of our emphasis has been on interpreting Airborne Visible/Infrared Imaging Spectrometry (AVIRIS) data spectral mixtures. Two approaches have been used, simple models, where the data are treated as a mixture of 3 to 4 laboratory/field measured spectra, known as reference endmembers (EM's), applied uniformly to the whole image, to more complex models where both the number of EM's and the types of EM's vary on a per-pixel basis. Where simple models are applied, materials, such as NPV, which are spectrally similar to soils, can be discriminated on the basis of residual spectra. One key aspect is that the data are calibrated to reflectance and modeled as mixtures of reference EM's, permitting temporal comparison of EM fractions, independent of scene location or data type. In previous studies the calibration was performed using a modified-empirical line calibration, assuming a uniform atmosphere across the scene. In this study, a Modtran-based calibration approach was used to map liquid water and atmospheric water vapor and retrieve surface reflectance from three AVIRIS scenes acquired in 1992 over the Jasper Ridge Biological Preserve. The data were acquired on June 2nd, September 4th and October 6th. Reflectance images were analyzed as spectral mixtures of reference EM's using a simple 4 EM model. Atmospheric water vapor derived from Modtran was compared to elevation, and community type. Liquid water was compare to the abundance of NPV, Shade and Green Vegetation (VG) for select sites to determine whether a relationship existed, and under what conditions the relationship broke down. Temporal trends in endmember fractions, liquid water and atmospheric water vapor were investigated also. The combination of spectral mixture analysis and the Modtran based atmospheric/liquid water models was used to develop a unique vegetation community description.

Roberts, Dar A.; Green, Robert O.; Sabol, Donald E.; Adams, John B.

1993-01-01

377

Upper tropospheric water vapor: A field campaign of two Raman lidars, Airborne hygrometers, and Radiosondes  

NASA Technical Reports Server (NTRS)

Water vapor in the atmosphere plays an important role in radiative transfer and the process of radiative balance so critical for understanding global change. It is the principal ingredient in cloud formation, one of the most difficult atmospheric processes to model, and the most variable component of the Earth-atmosphere albedo. And as a free molecule, it is the most active infrared absorber and emitter, thus, the most important greenhouse gas. The radiative impact of water vapor is important at all levels of the atmosphere. Even though moisture decreases by several orders-of-magnitude from the Earth's surface to the tropopause, recent research has shown that, from a radiative standpoint, a small percentage change in water vapor at any level is nearly equivalent. Therefore accurate and precise measurements of this important atmospheric constituent are needed at all levels to evaluate the full radiative impact. The need for improved measurements in the upper troposphere is particularly important because of the generally hostile (very dry and cold) conditions encountered. Because of the importance of water vapor to the understanding of radiative transfer, the Department of Energy's Atmospheric Radiation Measurements (ARM) program initiated a series of measurement campaigns at the Cloud And Radiation Testbed (CART) site in Oklahoma, especially focused on atmospheric water vapor. Three water vapor intensive observation period (water vapor IOP) campaigns were planned. Two of the water vapor IOP campaigns have been completed: the first IOP was held during the fall of 1996 with a focus on boundary layer water vapor measurements, and the second was conducted during the fall of 1997 with a focus on both boundary layer moisture e and moisture in the upper troposphere. This paper presents a review of the intercomparisons of water vapor measurements in the upper troposphere aquired during the second water vapor IOP. Data to be presented include water vapor measurements ements from: two Raman Lidars, the NASA Goddard Scanning Raman Lidar (SRL) and the CART Raman Lidar (CARL), a number of Vaisala radiosondes launched during the IOP campaign, and a dew point hygrometer flown on the University of North Dakota Cessna Citation Aircraft.

Melfi, S. Harvey; Turner, Dave; Evans, Keith; Whiteman, Dave; Schwemmer, Geary; Ferrare, Richard

1998-01-01

378

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

SciTech Connect

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

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

2008-01-01

379

Calculational model for condensation of water vapor during an underground nuclear detonation  

Microsoft Academic Search

An empirally derived mathematical model was developed to calculate the ; pressure and temperature history during condensation of water vapor in an ; underground-nuclear-explosion cavity. The condensation process is non-isothermal. ; Use has been made of the Clapeyron-Clausius equation as a basis for development ; of the model. Analytic fits to the vapor pressure and the latent heat of ;

Knox

1975-01-01

380

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

NASA Astrophysics Data System (ADS)

The thermodynamic properties of the troposphere, in particular water vapor content and temperature, change in response to physical mechanisms, including frictional drag, evaporation, transpiration, heat transfer and flow modification due to terrain. The planetary boundary layer (PBL) is characterized by a high rate of change in its thermodynamic state on time scales of typically less than one hour. Large horizontal gradients in vertical wind speed and steep vertical gradients in water vapor and temperature in the PBL are associated with high-impact weather. Observation of these gradients in the PBL with high vertical resolution and accuracy is important for improvement of weather prediction. Satellite remote sensing in the visible, infrared and microwave provide qualitative and quantitative measurements of many atmospheric properties, including cloud cover, precipitation, liquid water content and precipitable water vapor in the upper troposphere. However, the ability to characterize the thermodynamic properties of the PBL is limited by the confounding factors of ground emission in microwave channels and of cloud cover in visible and IR channels. Ground-based microwave radiometers are routinely used to measure thermodynamic profiles. The vertical resolution of such profiles retrieved from radiometric brightness temperatures depends on the number and choice of frequency channels, the scanning strategy and the accuracy of brightness temperature measurements. In the standard technique, which uses brightness temperatures from vertically pointing radiometers, the vertical resolution of the retrieved water vapor profile is similar to or larger than the altitude at which retrievals are performed. This study focuses on the improvement of the vertical resolution of water vapor retrievals by including scanning measurements at a variety of elevation angles. Elevation angle scanning increases the path length of the atmospheric emission, thus improving the signal-to-noise ratio. This thesis also discusses Colorado State University's (CSU) participation in the European Space Agency (ESA)'s "Mitigation of Electromagnetic Transmission errors induced by Atmospheric WAter Vapor Effects" (METAWAVE) experiment conducted in the fall of 2008. CSU deployed a ground-based network of three Compact Microwave Radiometers for Humidity profiling (CMR-Hs) in Rome to measure atmospheric brightness temperatures. These measurements were used to retrieve high-resolution 3-D atmospheric water vapor and its variation with time. High-resolution information about water vapor can be crucial for the mitigation of wet tropospheric path delay variations that limit the quality of Interferometric Synthetic Aperture Radar satellite interferograms. Three-dimensional water vapor retrieval makes use of radiative transfer theory, algebraic tomographic reconstruction and Bayesian optimal estimation coupled with Kalman filtering. In addition, spatial interpolation (kriging) is used to retrieve water vapor density at unsampled locations. 3-D humidity retrievals from Rome data with vertical and horizontal resolution of 0.5 km are presented. The water vapor retrieved from CMR-H measurements is compared with MM5 Mesoscale Model output, as well as with measurements from the Medium Resolution Imaging Spectrometer (MERIS) aboard ESA's ENVISAT and the Moderate Resolution Imaging Spectroradiometer (MODIS) aboard NASA's Aqua and Terra satellites.

Sahoo, Swaroop

2011-12-01

381

Twenty-Four-Hour Raman Lidar Water Vapor Measurements During the Atmospheric Radiation Measurement Program's 1996 and 1997 Water Vapor Intensive Observation Periods  

SciTech Connect

Prior to the Atmospheric Radiation Measurement program's first water vapor intensive observation period (WVIOP) at the Cloud and Radiation Testbed site near Lamont, Oklahoma, an automated 24-h Raman lidar was delivered to the site. This instrument, which makes high-resolution measurements of water vapor both spatially and temporally, is capable of making these measurements with no operator interaction (other than initial startup) for days at a time. Water vapor measurements collected during the 1996 and 1997 WVIOPs are discussed here, illustrating both the nighttime and daytime capabilities of this system. System characteristics, calibration issues, and techniques are presented. Finally, detailed intercomparisons of the lidar's data with those from a microwave radiometer, radiosondes, an instrumented tower, a chilled mirror flown on both a tethersonde and a kite, and measurements from aircraft are shown and discussed, highlighting the accuracy and stability of this system for both nighttime and daytime measurements.

Turner, David D.; Goldsmith, JE M.

1999-08-01

382

Lagrangian transport of water vapor and CFCs in a coupled Chemistry Climate Model  

NASA Astrophysics Data System (ADS)

We describe the implementation of a Lagrangian transport core in a chemistry climate model (CCM). Thereby we address the common problem of properly representing trace gas distributions in a classical Eulerian framework with a fixed model grid, particularly in regions with strong trace gas gradients. A prominent example is stratospheric water vapor, which is an important driver of surface climate change on decadal scales. In this case, the transport representation is particularly important in the tropical tropopause layer (TTL), where tropospheric air enters into the stratosphere. We have coupled the Chemical Lagrangian Model of the Stratosphere (CLaMS) with the ECHAM-MESSy Atmospheric Chemistry Model (EMAC). The latter includes the ECHAM5 climate model, and the MESSy interface, which allows for flexible coupling and switching between different submodels. The chemistry transport model CLaMS provides a fully Lagrangian transport representation to calculate constituent transport for an ensemble of air parcels that move along trajectories. To facilitate the calculation of long time-series a simplified chemistry scheme was implemented. Various studies show that the CLaMS model is particularly suited to properly represent dynamics and chemistry in the UT/LS region. The analysis of mean age of stratospheric air gives insight into the different transport characteristics of the Eulerian and the Lagrangian transport schemes. Mean age of air, calculated in both frameworks, is compared regarding the representation of important processes, i.e. descent in the polar vortex, upwelling in the tropical pipe, and isentropic in-mixing in subtropical regions. We also compared the zonal mean distributions and photochemical lifetimes of CFC-11 and CFC-12 with climatologies from different satellite experiments (ACE-FTS, HIRDLS, and MIPAS). CLaMS stratospheric water vapor distributions show remarkable differences compared to the stratospheric water vapor simulated by ECHAM, especially in the Northern hemisphere in summer. The results are compared to statellite water vapor mesurements. Qualitatively, Lagrangian CLaMS data are in better agreement with the satellite climatologies. It can be expected that the more accurate representation of the UT/LS region with the CLaMS model likely yields to improved climate predictions.

Hoppe, Charlotte; Müller, Rolf; Hoffmann, Lars; Konopka, Paul; Plöger, Felix; Grooß, Jens-Uwe

2013-04-01

383

Infrared and vapor flux studies of vapor-deposited amorphous and crystalline water ice films between 90 and 145 K  

Microsoft Academic Search

Three methods were simultaneously employed to investigate vapor-deposited water ice films (90-145 K) in a high-vacuum chamber: grazing-angle Fourier transform infrared (FTIR)-reflection absorption spectroscopy to characterize ice phase; optical interference methods to monitor ice density, growth rate, and film thickness; and gas phase mass spectrometry to monitor sublimation flux during annealing. The results of this work were used to further

Sabrina La Spisa; Matthew Waldheim; Jaime Lintemoot; Tiffany Thomas; Janelle Naff; Marin Robinson

2001-01-01

384

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

385

Electrification in Hurricanes over the Tropical Americas: Implication for Stratospheric Water Vapor  

NASA Technical Reports Server (NTRS)

This study explores the relation between lightning activity and water vapor in the Tropical Tropopause Layer (TTL) over hurricane systems in the Tropical Americas. The hypothesis herein is that hurricanes that exhibit enhanced lightning activity are associated with stronger updrafts that can transport more moisture directly into the TTL (and subsequently into the tropical stratosphere) or even directly into the tropical stratosphere over this region. The TTL over the Tropical Americas, which includes the Caribbean and Gulf of Mexico, is of particular interest, because summertime cold point tropopause is the lowest in height and thus the warmest in temperature over the tropics. The latter condition implies higher saturation values and thus potential for more water vapor to enter the stratosphere. Climate forecast is very sensitive to stratospheric water vapor abundance, because of the key role that water vapor plays in regulating the chemical and radiative properties of the stratosphere. Given the potential for increases in hurricane intensity and frequency under predicted warmer conditions, it becomes essential to understand the effect of hurricanes on stratospheric water vapor. In this study, we use a combination of ground and space-borne observations as well as trajectory calculations. The observations include: cloud-to-ground (CG) lightning data from the U.S. National Lightning Detection Network (NLDN), geostationary infrared observations from the National Climatic Data Center Hurricane Satellite (HURSAT) data set, cloud properties from Aqua-MODIS, and water vapor from Aura-MLS. We analyze hurricanes from the 2005 season when Aura-MLS data are available, namely: Dennis, Emily, Katrina, Rita, and Wilma. Our analysis consists of examining CG lightning, cloud-top properties, and TTL water vapor (i.e., 100 and 147 mb) over the hurricane while it remains over water in the Tropical Americas region. We investigate daily as well as diurnal statistical properties. The hurricanes analyzed in this study showed that lightning activity is negatively correlated with minimum infrared brightness temperature and positively correlated with 100-mb water vapor. An examination of the maxima in water vapor observed over the hurricane not only shows larger magnitudes, but also larger differences between water vapor averages and water vapor maxima over the hurricane as lightning activity increases. Trajectory calculations are performed using the Flextra model in order to investigate the fate of the moister air masses found in the TTL.

Pittman, Jasna V.; Chronis, Themis G.; Robertson, Franklin R.; Miller, Timothy L.

2007-01-01

386

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

PubMed

Recently measured properties of water vapor (H(2)O) absorption lines have been used in calculations to evaluate the temperature sensitivity of differential absorption lidar (DIAL) H(2)O measurements. This paper estimates the temperature sensitivity of H(2)O lines in the 717-733-nm region for both H(2)O mixing ratio and number density measurements, and discusses the influence of the H(2)O line ground state energies E'', the H(2)O 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 sixty-seven H(2)O lines in the 720-nm band are given which can be directly used in field experiments. Water vapor lines with E'' values in the 100-300-cm(-1) range were found to be optimum for DIAL measurements of H(2)O number densities, while E'' values in the 250-500-cm(-1) range were found to be optimum for H(2)O mixing ratio measurements. PMID:20700314

Browell, E V; Ismail, S; Grossmann, B E

1991-04-20

387

Time-dependent response of a charcoal bed to radon and water vapor in flowing air  

SciTech Connect

Extremely high airborne concentrations of radon gas may be encountered during the remediation of uranium mill tailings storage facilities. Radon is also a constituent of the off-gas of mill-tailing vitrification. An effective way to remove radon from either gas is to pass the gas through a packed bed containing activated charcoal. Measurements of radon concentrations in the environment using charcoal canisters were first described by George. Canisters similar to those used by George in his first experiments have become the U.S. Environmental Protection Agency`s (EPA`s) standard for measuring environmental radon and were described in the EPA protocol for environmental radon measurement. The dynamic behavior of EPA charcoal canisters has been previously described with a mathematical model for the kinetics of radon gas adsorption in air in the presence of water vapor. This model for charcoal canisters has been extended to large charcoal beds with flowing air containing radon and water vapor. The mathematical model for large charcoal beds can be used to evaluate proposed bed designs or to model existing beds. Parameters that affect the radon distribution within a charcoal bed that can be studied using the mathematical model include carrier gas relative humidity and flow velocity, and input radon concentration. In addition, the relative performances of several different charcoals can be studied, provided sufficient information about their adsorption, desorption, and diffusion constants is known.

Henkel, J.A.; Fentiman, A.W.; Blue, T.E. [Ohio State Univ., Columbus, OH (United States)

1995-12-31

388

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

389

Water Vapor Turbulence Profiles in Stationary Continental Convective Mixed Layers  

SciTech Connect

The U.S. Department of Energy Atmospheric Radiation Measurement (ARM) program’s Raman lidar at the ARM Southern Great Plains (SGP) site in north-central Oklahoma has collected water vapor mixing ratio (q) profile data more than 90% of the time since October 2004. Three hundred (300) cases were identified where the convective boundary layer was quasi-stationary and well-mixed for a 2-hour period, and q mean, variance, third order moment, and skewness profiles were derived from the 10-s, 75-m resolution data. These cases span the entire calendar year, and demonstrate that the q variance profiles at the mixed layer (ML) top changes seasonally, but is more related to the gradient of q across the interfacial layer. The q variance at the top of the ML shows only weak correlations (r < 0.3) with sensible heat flux, Deardorff convective velocity scale, and turbulence kinetic energy measured at the surface. The median q skewness profile is most negative at 0.85 zi, zero at approximately zi, and positive above zi, where zi is the depth of the convective ML. The spread in the q skewness profiles is smallest between 0.95 zi and zi. The q skewness at altitudes between 0.6 zi and 1.2 zi is correlated with the magnitude of the q variance at zi, with increasingly negative values of skewness observed lower down in the ML as the variance at zi increases, suggesting that in cases with larger variance at zi there is deeper penetration of the warm, dry free tropospheric air into the ML.

Turner, D. D.; Wulfmeyer, Volker; Berg, Larry K.; Schween, Jan

2014-10-08

390

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

391

Water Vapor in nearby Infrared Galaxies as Probed by Herschel  

NASA Astrophysics Data System (ADS)

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 H2O emission line detected. The H2O line luminosities range from ~1 × 105 L ? to ~5 × 107 L ? while the total IR luminosities (L IR) have a similar spread (~1-300 × 1010 L ?). In addition, emission lines of H2O+ and H_2^{18}O are also detected. H2O is found, for most galaxies, to be the strongest molecular emitter after CO in FTS spectra. The luminosity of the five most important H2O lines is near-linearly correlated with L IR, regardless of whether or not strong active galactic nucleus signature is present. However, the luminosity of H2O(211-202) and H2O(220-211) appears to increase slightly faster than linear with L IR. Although the slope turns out to be slightly steeper when z ~ 2-4 ULIRGs are included, the correlation is still closely linear. We find that L_{H_2O}/L IR decreases with increasing f 25/f 60, but see no dependence on f 60/f 100, possibly indicating that very warm dust contributes little to the excitation of the submillimeter H2O 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 H2O(202-111) and H2O(321-312). Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.

Yang, Chentao; Gao, Yu; Omont, A.; Liu, Daizhong; Isaak, K. G.; Downes, D.; van der Werf, P. P.; Lu, Nanyao

2013-07-01

392

Water vapor turbulence profiles in stationary continental convective mixed layers  

NASA Astrophysics Data System (ADS)

U.S. Department of Energy Atmospheric Radiation Measurement (ARM) program's Raman lidar at the ARM Southern Great Plains site in north central Oklahoma has collected water vapor mixing ratio (q) profile data more than 90% of the time since October 2004. Three hundred (300) cases were identified where the convective boundary layer was quasi-stationary and well mixed for a 2 h period, and q mean, variance, third-order moment, and skewness profiles were derived from the 10 s, 75 m resolution data. These cases span the entire calendar year, and demonstrate that the q variance profiles at the mixed layer (ML) top changes seasonally and is strongly related to the gradient of q across the interfacial layer. The q variance at the top of the ML shows only weak correlations (r < 0.3) with sensible heat flux, Deardorff convective velocity scale, and turbulence kinetic energy measured at the surface. The median q skewness profile is most negative at 0.85 zi, zero at approximately zi, and positive above zi, where zi is the depth of the convective ML. The spread in the q skewness profiles is smallest between 0.95 zi and zi. The q skewness at altitudes between 0.6 zi and 1.2 zi is correlated with the magnitude of the q variance at zi, with increasingly negative values of skewness observed lower down in the ML as the variance at zi increases, suggesting that in cases with larger variance at zi there is deeper penetration of the warm, dry free tropospheric air into the ML.

Turner, D. D.; Wulfmeyer, V.; Berg, L. K.; Schween, J. H.

2014-10-01

393

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

394

Comparison of active and passive water vapor remote sensing from space: An analysis based on the simulated performance of IASI and space borne differential absorption lidar  

Microsoft Academic Search

Two remote sensing systems, which are considered to be operated in space, the Infrared Atmospheric Sounding Interferometer (IASI) and the Water Vapour Lidar Experiment in Space (WALES) are compared with respect to their measurement methodologies and their performance. The focus is the retrieval of water vapor, which is determined by the inversion of the radiative transfer equation in case of

V. Wulfmeyer; Heinz Bauer; Paolo Di Girolamo; Carmine Serio

2005-01-01

395

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

John Waldrop

2002-02-06

396

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

397

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

398

Physical Mechanisms Controlling Upper Tropospheric Water Vapor as Revealed by MLS Data from UARS  

NASA Technical Reports Server (NTRS)

The third year and final report on the physical mechanisms controlling upper tropospheric water vapor revealed by the Microwave Limb Sounder (MLS) on the Upper Atmosphere Research Satellite (UARS) is presented.

Newell, Reginald E.; Douglass, Anne (Technical Monitor)

2002-01-01

399

Observations of the Upper Tropospheric Water Vapor Feedback in UARS MLS and HALOE Data  

NASA Technical Reports Server (NTRS)

One of the biggest uncertainties in climate science today concerns the water vapor feedback. Most GCMs hold relative humidity fixed as the climate changes, which provides a strong positive feedback to warming due from anthropogenic greenhouse gas emissions. Some in the community, on the other hand, have speculated that tropospheric specific humidity will remain fixed as the climate changes. Observational studies have attempted to resolve this disagreement, but the results have been inconclusive, and few of the studies have focused on the upper troposphere (UT). This is a significant oversight: the surface temperature is especially sensitive to changes in water vapor in the UT owing to the cold temperatures found there. We present an analysis of UARS MLS and HALOE water vapor measurements at 21 5 hPa. We find strong evidence that the water vapor feedback in the UT is positive, but not as strong as fixed relative humidity scenarios. This suggests that GCMs are overestimating the sensitivity of the climate.

Dessler, A. E.; Minschwaner, K. R.

2004-01-01

400

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

DOEpatents

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

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

2011-08-23

401

Quantifying consistency and biases between aircraft, balloon and remote sensing measurements of UT/LS water vapor during the WB-57 NASA MACPEX mission  

NASA Astrophysics Data System (ADS)

Mixing ratios of water vapor in Earth's upper troposphere and lower stratosphere (UT/LS) are low (< 10 ppmv), yet water in this region is a significant driver of climate. Significant discrepancies have repeatedly been observed between multiple high precision measurements of water vapor at these low values in the UT/LS, leading to uncertainty in the absolute value of the direct radiative forcing from stratospheric water vapor. During the NASA Mid-latitude Airborne Cirrus Properties Experiment (MACPEX) mission in March and April of 2011, measurements of water vapor in the UT/LS were made using the NOAA chemical ionization mass spectrometer (CIMS) and Harvard Lyman-? water vapor (HWV) instruments integrated on the NASA WB-57 based out of Ellington Field, TX. This was the first aircraft deployment of the CIMS instrument configured to measure water vapor. The CIMS carried a novel in situ calibration system using two independent water vapor standards that were in excellent agreement throughout the campaign. CIMS was also in excellent agreement with HWV, which operates and is calibrated using fundamentally different principles. The redundant and independent calibration systems of CIMS and HWV afford new confidence in the accuracy of these aircraft measurements. We compare these aircraft measurements of water vapor to those made with the MLS instrument on the AURA satellite, and to frost point balloon borne (NOAA FPH and CFH) measurements coordinated with the WB-57 descents from the LS. A persistent bias of 0.7 ppmv is observed between the frost point and aircraft measurements in the 3 to 10 ppmv range, with frost point being lower. The MLS measurements are less precise, but generally fall between the balloon and aircraft measurements in the LS. These measurements renew interest in comparisons in the tropics where even lower mixing ratios and higher saturations with respect to ice are encountered.

Gao, R.; Rollins, A.; Thornberry, T. D.; Hall, E.; Jordan, A.; Hurst, D. F.; Smith, J. B.; Sargent, M. R.; Fahey, D. W.

2011-12-01

402

Development of a deployable aerosol\\/water vapor lidar to characterize the atmosphere  

Microsoft Academic Search

A trailer-based lidar, named Humidity and Aerosol Lidar (HAL), is being built as a remote sensing tool to characterize atmospheric aerosol and water vapor in the line-of-sight. Water vapor and aerosol in the lower atmosphere are critical components affecting the propagation of high-energy laser beams and microwave. The sensor is developed to collect high temporal and vertical resolution data of

Phan D. Dao; Anthony Dentamaro

2003-01-01

403

The Surface Chemistry of Condensation Nuclei: III. The Adsorption of Water Vapor on `Doped' Silver Iodide  

Microsoft Academic Search

Adsorption isotherms at 10C for water vapor on `pure' silver iodide and silver iodide doped with 0.60 avid 0.12 weight per cent of potassium nitrate have been determined by a volumetric method. It has been demonstrated that the addition of hygroscopic contaminants to silver iodide increases its efficiency in the nucleation of ice from supercooled water vapor. The adsorption of

M. L. Corrin; S. P. Moulik; B. Cooley

1967-01-01

404

Observations of accelerated silicon carbide recession by oxidation at high water-vapor pressures  

Microsoft Academic Search

A study of the exposure of SiC at 1,200 C and high water-vapor pressures (1.5 atm) has shown SiC recession rates that exceed what is predicted based on parabolic oxidation at water-vapor pressures of less than or equal to â¼1 atm. After exposure to these conditions, distinct silica-scale structures are observed; thick, porous, nonprotective cristobalite scales form above a thin,

Karren L. More; Peter F. Tortorelli; Mattison K. Ferber; James R. Keiser

2000-01-01

405

What Can Water Vapor Reveal About Past and Future Climate Change?  

Microsoft Academic Search

AGU Chapman Conference on Water Vapor and Its Role in Climate; Kailua-Kona, Hawaii, 20-24 October 2008; An AGU Chapman Conference on water vapor was held in Hawaii with approximately 120 attendees from nine countries. The meeting began with a keynote presentation on the hydrological cycle and climate change and continued with sessions on issues related to the upper troposphere\\/lower stratosphere

Steven C. Sherwood; Natalia Andronova; Eric Fetzer; E. Robert Kursinski

2009-01-01

406

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

407

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

408