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Supersaturation in the Spontaneous Formation of Nuclei in Water Vapor

Description: "According to experience, a certain supersaturation is required for condensation of water vapor in the homogeneous phase; that is, for inception of the condensation, at a prescribed temperature, the water vapor partial pressure must lie above the saturation pressure. The condensation starts on so-called condensation nuclei. Solid or liquid suspended particles may serve as nuclei; these particles may either a priori be present in the gas phase (dust, soot), or may spontaneously be formed from the vapor molecules to be condensed themselves" (p. 1).
Date: November 1953
Creator: Sander, Adolf & Damköhler, Gerhard
Partner: UNT Libraries Government Documents Department

The Effect of Compressor-Inlet Water Injection on Engine and Afterburner Performance

Description: Report presenting testing of a turbojet engine incorporating a conventional-type afterburner over a range of afterburner pressure levels and engine-inlet water-air ratios. At each pressure level and water-air ratio, the afterburner fuel flow was varied from lean blowout to maximum burner-outlet temperature. Results regarding the effects of water vapor on engine performance, effects of water vapor on afterburner performance, and high Mach number performance with water injection are provided.
Date: July 22, 1958
Creator: Sivo, Joseph N.; Wanhainen, John P. & Jones, William L.
Partner: UNT Libraries Government Documents Department

Rate of reaction of gaseous fluorine with water vapor at 35 degrees C

Description: Report presenting testing of fluorine and water vapor, which react extremely slowly or not at all in the gas phase at 35 degrees Celsius at partial pressures of the reactants up to 40 mm of mercury. Results regarding the gross nature of the reaction, order of the reaction, kinetics of surface and gas-phase reactions, relative importance of surface and gas-phase reactions, and rate of surface reaction are provided.
Date: September 1958
Creator: Slabey, Vernon A. & Fletcher, Edward A.
Partner: UNT Libraries Government Documents Department

The Effect of Water Vapor on Flame Velocity in Equivalent Carbon Monoxide and Oxygen Mixtures

Description: This report presents the results of an investigation to study the effect of water vapor upon the spatial speed of flame in equivalent mixtures of carbon monoxide and oxygen at various total pressures from 100 to 780 mm.hg. These results show that, within this pressure range, an increase in flame speed is produced by increasing the mole fraction of water vapor at least as far as saturation at 25 degrees c., and that the rate of this increase is greater the higher the pressure. It is evident that water vapor plays an important part in the explosive oxidation of carbon monoxide; the need for further experimental evidence as to the nature of its action is indicated.
Date: January 10, 1935
Creator: Fiock, Ernest F. & King, H. Kendall
Partner: UNT Libraries Government Documents Department

A comparison of water vapor quantities from model short-range forecasts and ARM observations

Description: Model evolution and improvement is complicated by the lack of high quality observational data. To address a major limitation of these measurements the Atmospheric Radiation Measurement (ARM) program was formed. For the second quarter ARM metric we will make use of new water vapor data that has become available, and called the 'Merged-sounding' value added product (referred to as OBS, within the text) at three sites: the North Slope of Alaska (NSA), Darwin Australia (DAR) and the Southern Great Plains (SGP) and compare these observations to model forecast data. Two time periods will be analyzed March 2000 for the SGP and October 2004 for both DAR and NSA. The merged-sounding data have been interpolated to 37 pressure levels (e.g., from 1000hPa to 100hPa at 25hPa increments) and time averaged to 3 hourly data for direct comparison to our model output.
Date: March 17, 2006
Creator: Hnilo, J J
Partner: UNT Libraries Government Documents Department

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

Description: 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.
Date: February 6, 2006
Creator: Braun, John
Partner: UNT Libraries Government Documents Department

On Sensitivity of Spectral Radiative Fluxes to Atmospheric Water Vapor in the 940 nm Region (Numerical Simulation)

Description: Water vapor is well known to be a critical component in many aspects of atmospheric research, such as radiative transfer and cloud and aerosol processes. This requires both improved measurements of the columnar water vapor and its profiles in the atmosphere in a wide range of conditions, and adjustment of water vapor parameterizations in radiation codes including the perfection of spectroscopic parameters. In this paper we will present the results of comparison of our calculations and downward solar fluxes measured with Rotating Shadowband Spectroradiometer under conditions of horizontally homogeneous clouds. We also will discuss the sensitivity of atmospheric radiation characteristics to variations of water vapor in the band 940 nm: these results may be useful for development of new methods of retrieval of the total column water vapor content (WVC) in the atmosphere from data of radiation observations.
Date: March 18, 2005
Creator: Zhuravleva, T.B. & Firsov, K.M.
Partner: UNT Libraries Government Documents Department

Microwave Radiometer – 3 Channel (MWR3C) Handbook

Description: The microwave radiometer 3-channel (MWR3C) provides time-series measurements of brightness temperatures from three channels centered at 23.834, 30, and 89 GHz. These three channels are sensitive to the presence of liquid water and precipitable water vapor.
Date: May 4, 2012
Creator: Cadeddu, MP
Partner: UNT Libraries Government Documents Department

Scanning ARM Cloud Radar Handbook

Description: The scanning ARM cloud radar (SACR) is a polarimetric Doppler radar consisting of three different radar designs based on operating frequency. These are designated as follows: (1) X-band SACR (X-SACR); (2) Ka-band SACR (Ka-SACR); and (3) W-band SACR (W-SACR). There are two SACRs on a single pedestal at each site where SACRs are deployed. The selection of the operating frequencies at each deployed site is predominantly determined by atmospheric attenuation at the site. Because RF attenuation increases with atmospheric water vapor content, ARM's Tropical Western Pacific (TWP) sites use the X-/Ka-band frequency pair. The Southern Great Plains (SGP) and North Slope of Alaska (NSA) sites field the Ka-/W-band frequency pair. One ARM Mobile Facility (AMF1) has a Ka/W-SACR and the other (AMF2) has a X/Ka-SACR.
Date: June 18, 2012
Creator: Widener, K; Bharadwaj, N & Johnson, K
Partner: UNT Libraries Government Documents Department

Eddy Correlation Flux Measurement System (ECOR) Handbook

Description: The eddy correlation (ECOR) flux measurement system provides in situ, half-hour measurements of the surface turbulent fluxes of momentum, sensible heat, latent heat, and carbon dioxide (CO2) (and methane at one Southern Great Plains extended facility (SGP EF) and the North Slope of Alaska Central Facility (NSA CF). The fluxes are obtained with the eddy covariance technique, which involves correlation of the vertical wind component with the horizontal wind component, the air temperature, the water vapor density, and the CO2 concentration.
Date: January 31, 2011
Creator: Cook, DR
Partner: UNT Libraries Government Documents Department

Microwave Radiometer (MWR) Handbook

Description: The Microwave Radiometer (MWR) provides time-series measurements of column-integrated amounts of water vapor and liquid water. The instrument itself is essentially a sensitive microwave receiver. That is, it is tuned to measure the microwave emissions of the vapor and liquid water molecules in the atmosphere at specific frequencies.
Date: August 1, 2006
Creator: Morris, VR
Partner: UNT Libraries Government Documents Department


Description: Determining columnar water vapor is a fundamental problem in remote sensing. This measurement is important both for understanding atmospheric variability and also from removing atmospheric effects from remotely sensed data. Therefore discovering a reliable and if possible automated method for determining water vapor column abundance is important. There are two standard methods for determining precipitable water vapor during the daytime from multi-spectral data. The first method is the Continuum Interpolated Band Ratio (CIBR) (see for example King et al. 1996). This method assumes a baseline and measures the depth of a water vapor feature as compared to this baseline. The second method is the Atmospheric Pre-corrected Differential Absorption technique (APDA) (see Schlaepfer et al. 1998); this method accounts for the path radiance contribution to the top of atmosphere radiance measurement which is increasingly important at lower and lower reflectance values. We have also developed two methods of modifying CIBR. We use a simple curve fitting procedure to account for and remove any systematic errors due to low reflectance while still preserving the random spread of the CIBR values as a function of surface reflectance. We also have developed a two-dimensional look-up table for CIBR; CIBR using this technique is a function of both water vapor (as with all CIBR techniques) and surface reflectance. Here we use data recently acquired with the Multi-spectral Thermal Imager spacecraft (MTI) to compare these four methods of determining columnar water vapor content.
Date: March 1, 2001
Creator: HIRSCH, K. & AL, ET
Partner: UNT Libraries Government Documents Department


Description: The basic goals of the research are to develop and test algorithms and deploy instruments that improve measurements of water vapor, cloud liquid, and cloud coverage, with a focus on the Arctic conditions of cold temperatures and low concentrations of water vapor. The importance of accurate measurements of column amounts of water vapor and cloud liquid has been well documented by scientists within the Atmospheric Radiation Measurement Program. Although several technologies have been investigated to measure these column amounts, microwave radiometers (MWR) have been used operationally by the ARM program for passive retrievals of these quantities: precipitable water vapor (PWV) and integrated water liquid (IWL). The technology of PWV and IWL retrievals has advanced steadily since the basic 2-channel MWR was first deployed at ARM CART sites Important advances are the development and refinement of the tipcal calibration method [1,2], and improvement of forward model radiative transfer algorithms [3,4]. However, the concern still remains that current instruments deployed by ARM may be inadequate to measure low amounts of PWV and IWL. In the case of water vapor, this is especially important because of the possibility of scaling and/or quality control of radiosondes by the water amount. Extremely dry conditions, with PWV less than 3 mm, commonly occur in Polar Regions during the winter months. Accurate measurements of the PWV during such dry conditions are needed to improve our understanding of the regional radiation energy budgets. The results of a 1999 experiment conducted at the ARM North Slope of Alaska/Adjacent Arctic Ocean (NSA/AAO) site during March of 1999 [5] have shown that the strength associated with the 183 GHz water vapor absorption line makes radiometry in this frequency regime suitable for measuring low amounts of PWV. As a portion of our research, we conducted another millimeter wave radiometric experiment at the ...
Date: November 1, 2004
Creator: Westwater, E. R.; Leuskiy, V. V.; Klein, M.; Gasiewski, A. J. & Shaw, and J. A.
Partner: UNT Libraries Government Documents Department

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

Description: Abstract - ProSensing Inc. has developed a G-band (183 GHz) water Vapor Radiometer (GVR) for long-term, unattended measurements of low concentrations of atmospheric water vapor and liquid water. Precipitable water vapor and liquid water path are estimated from zenith brightness temperatures measured from four double-sideband receiver channels, centered at 183.31 1, 3 and 7, and 14 GHz. A prototype ground-based version of the instrument was deployed at the DOE ARM program?s North Slope of Alaska site near Barrow AK in April 2005, where it collected data continuously for one year. A compact, airborne version of this instrument, packaged to operate from a standard 2-D PMS probe canister, has been tested on the ground and is scheduled for test flights in the summer of 2006. This paper presents design details, laboratory test results and examples of retrieved precipitable water vapor and liquid water path from measured brightness temperature data.
Date: November 9, 2006
Creator: Pazmany, Andrew
Partner: UNT Libraries Government Documents Department

Enhancing the precision and accuracy within and among AmeriFlux site measurements

Description: This is the final report for AmeriFlux QA/QC at Oregon State University. The major objective of this project is to contribute to the AmeriFlux network by continuing to build consistency in AmeriFlux measurements by addressing objectives stated in the AmeriFlux strategic plan and self evaluation, the North American Carbon Program, and the US Carbon Cycle Science Program. The project directly contributes to NACP and CCSP goals to establish an integrated, near-real time network of observations to inform climate change science.
Date: November 25, 2013
Creator: Law, Bev
Partner: UNT Libraries Government Documents Department

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

Description: Robust, economical, low-power and reliable closed-path methane (CH4), carbon dioxide (CO2), and water vapor (H2O) analyzers suitable for long-term measurements are not readily available commercially. Such analyzers are essential for quantifying the amount of CH4 and CO2 released from various ecosystems (wetlands, rice paddies, forests, etc.) and other surface contexts (e.g. landfills, animal husbandry lots, etc.), and for understanding the dynamics of the atmospheric CH4 and CO2 budget and their impact on climate change and global warming. The purpose of this project is to develop a closed-path methane, carbon dioxide gas and water vapor analyzer capable of long-term measurements in remote areas for global climate change and environmental research. The analyzer will be capable of being deployed over a wide range of ecosystems to understand methane and carbon dioxide exchange between the atmosphere and the surface. Measurements of methane and carbon dioxide exchange need to be made all year-round with limited maintenance requirements. During this Phase II effort, we successfully completed the design of the electronics, optical bench, trace gas detection method and mechanical infrastructure. We are using the technologies of two vertical cavity surface emitting lasers, a multiple-pass Herriott optical cell, wavelength modulation spectroscopy and direct absorption to measure methane, carbon dioxide, and water vapor. We also have designed the instrument application software, Field Programmable Gate Array (FPGA), along with partial completion of the embedded software. The optical bench has been tested in a lab setting with very good results. Major sources of optical noise have been identified and through design, the optical noise floor is approaching -60dB. Both laser modules can be temperature controlled to help maximize the stability of the analyzer. Additionally, a piezo electric transducer has been utilized to randomize the noise introduced from potential etalons. It is expected that all original specifications contained within the ...
Date: May 1, 2012
Creator: Liukang, Xu; Dayle, McDermitt; Tyler, Anderson; Brad, Riensche; Anatoly, Komissarov & Julie, Howe
Partner: UNT Libraries Government Documents Department

The Refurbishment and Upgrade of the Atmospheric Radiation Measurement Raman Lidar

Description: The Atmospheric Radiation Measurement Program (ARM) Climate Research Facility (ACRF) Raman lidar (CARL) is an autonomous, turn-key system that profiles water vapor, aerosols, and clouds throughout the diurnal cycle for days without attention (Goldsmith et al. 1998). CARL was first deployed to the Southern Great Plains CRF during the summer of 1996 and participated in the 1996 and 1997 water vapor intensive operational periods (IOPs). Since February 1998, the system has collected over 38,000 hrs of data (equivalent of almost 4.4 years), with an average monthly uptime of 62% during this time period. This unprecedented performance by CARL makes it the premier operational Raman lidar in the world. Unfortunately, CARL began degrading in early 2002. This loss of sensitivity, which affected all observed variables, was very gradual and thus was not identified until the autumn of 2003. Analysis of the data suggested the problem was not associated with the laser or transmit portion of the system, but rather in the detection subsystem, as both the background values and the peak signals showed a marked decreases over this time period. The loss of sensitivity of a factor of 2-4, depending on the channel, resulted in higher random error in the retrieved products, such as the aerosol backscatter coefficient and water vapor mixing ratio. Figure 1 shows the random error at 2 km for aerosol backscatter coefficient (top) and water vapor mixing ratio (middle), in terms of percent of the signal for both average daytime (red) and nighttime (blue) data from 1998 to 2005. The seasonal variation of water vapor is easily seen in the random error in the water vapor mixing ratio data. The loss of sensitivity also affected the maximum range of the usable data, as illustrated by the dramatic decrease in the maximum height seen in the water vapor ...
Date: March 18, 2005
Creator: Turner, D.D. & Goldsmith, J.E.M.
Partner: UNT Libraries Government Documents Department

Femtosecond pulse damage thresholds of dielectric coatings in vacuum

Description: At 10-7 Torr, the multiple femtosecond pulse damage threshold, F(?), is about 10% of the single pulse damage fluence F(1) for hafnia and silica films compared to about 65% and 50%, respectively, at 630 Torr. In contrast, the single-pulse damage threshold is pressure independent. The decrease of F(?) with decreasing air pressure correlates with the water vapor and oxygen content of the ambient gas with the former having the greater effect. The decrease in F(?) is likely associated with an accumulation of defects derived from oxygen deficiency, for example vacancies. From atmospheric air pressure to pressures of {approx}3 x 10{sup -6} Torr, the damage 'crater' starts deterministically at the center of the beam and grows in diameter as the fluence increases. At pressure below 3x10-6 Torr, damage is initiated at random 'sites' within the exposed area in hafnia films, while the damage morphology remains deterministic in silica films. A possible explanation is that absorbing centers are created at predisposed sample sites in hafnia, for example at boundaries between crystallites, or crystalline and amorphous phases.
Date: March 1, 2011
Creator: Michelle D. Shinn, Duy N. Nguyen, Luke A. Emmert ,Paul Schwoebel, Dinesh Patel, Carmen S. Menoni, Wolfgang Rudolph
Partner: UNT Libraries Government Documents Department


Description: The potential for a fire while repackaging plutonium-contaminated scrap was evaluated. The surface-to-mass ratio indicates the metal alone will not spontaneously ignite. Uranium hydride can form when uranium metal is exposed to water vapor or hydrogen; uranium hydride reacts rapidly and energetically with atmospheric oxygen. The plutonium-contaminated scrap has been inside containers qualified for shipping, and these containers are leak-tight. The rate of diffusion of water vapor through the seals is small, and the radiolytic hydrogen generation rate is low. Radiography of samples of the storage containers indicates no loose oxide/hydride powder has collected in the storage container to date. The frequently of a fire while repackaging the plutonium-contaminated scrap is extremely unlikely.
Date: December 18, 2003
Creator: Hallman, D
Partner: UNT Libraries Government Documents Department

Multifilter Rotating Shadowband Radiometer (MFRSR) Handbook

Description: The visible Multifilter Rotating Shadowband Radiometer (MFRSR) is a passive instrument that measures global and diffuse components of solar irradiance at six narrowband channels and one open, or broadband, channel (Harrison et al. 1994). Direct irradiance is not a primary measurement, but is calculated using the diffuse and global measurements. To collect one data record, the MFRSR takes measurements at four different shadowband positions. The first measurement is taken with the shadowband in the nadir (home) position. The next three measurements are, in order, the first side-band, sun-blocked, and second side-band. The side-band measurements are used to correct for the portion of the sky obscured by the shadowband. The nominal wavelengths of the narrowband channels are 415, 500, 615, 673, 870, and 940 nm. From such measurements, one may infer the atmosphere's aerosol optical depth at each wavelength. In turn, these optical depths may be used to derive information about the column abundances of ozone and water vapor (Michalsky et al. 1995), as well as aerosol (Harrison and Michalsky 1994) and other atmospheric constituents.
Date: February 7, 2011
Creator: Hodges, GB & Michalsky, JJ
Partner: UNT Libraries Government Documents Department

MWRRET Value-Added Product: The Retrieval of Liquid Water Path and Precipitable Water Vapor from Microwave Radiometer (MWR) Data Sets (Revision 2)

Description: This report provides a short description of the Atmospheric Radiation Measurement (ARM) Climate Research Facility microwave radiometer (MWR) Retrieval (MWRRET) value-added product (VAP) algorithm. This algorithm utilizes a complementary physical retrieval method and applies brightness temperature offsets to reduce spurious liquid water path (LWP) bias in clear skies resulting in significantly improved precipitable water vapor (PWV) and LWP retrievals. We present a general overview of the technique, input parameters, output products, and describe data quality checks. A more complete discussion of the theory and results is given in Turner et al. (2007b).
Date: July 25, 2011
Creator: Gaustad, KL; Turner, DD & McFarlane, SA
Partner: UNT Libraries Government Documents Department