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Articles 1021 - 1037 of 1037

Full-Text Articles in Physical Sciences and Mathematics

Gravity Wave-Driven Fluctuations In Oh Nightglow From An Extended, Dissipative Emission Region, G. Schubert, R. L. Walterscheid, Michael P. Hickey Ph.D. Aug 1991

Gravity Wave-Driven Fluctuations In Oh Nightglow From An Extended, Dissipative Emission Region, G. Schubert, R. L. Walterscheid, Michael P. Hickey Ph.D.

Publications

The theory of gravity wave-driven fluctuations in the OH nightglow from an extended source region is generalized to account for effects of eddy kinematic viscosity ν and eddy thermal diffusivity κ. In the nondiffusive case, the amplitudes and phases of vertically integrated normalized intensity 〈δI〉/〈Ī〉 and temperature 〈δTI〉/〈ĪI〉perturbations and vertically integrated Krassovsky's ratio 〈η〉 as functions of period are influenced by the upper limit of vertical integration of the extended source, especially at long periods when vertical wavelengths λᵥ are small. The effects, which include oscillations in 〈δT〉/〈Ī〉 , and 〈η〉, particularly at ...


A Simulation And Diagnostic Study Of Water Vapor Image Dry Bands, Bradley M. Muller, Henry E. Fuelberg Mar 1990

A Simulation And Diagnostic Study Of Water Vapor Image Dry Bands, Bradley M. Muller, Henry E. Fuelberg

Publications

A Limited Area Mesoscale Prediction System (LAMPS) model simulation and special 3-hour radiosonde dataset are used to investigate warm (dry) bands in 6,7 μm water vapor satellite imagery on 6–7 March 1982. The purpose is to reveal processes resulting in the formation and evolution of the dry features that appear as curving dark streaks in the imagery. Model soundings are input to a radiative transfer algorithm to generate synthetic 6.7 μm equivalent blackbody temperatures (TB) which are compared with those from the Visible infrared Spin Scan Radiometer Atmospheric Sounder aboard the Geostationary Operational Environmental Satellite. Simulated and ...


Biological Reductive Dechlorination Of Tetrachloroethylene And Trichloroethylene To Ethylene Under Methanogenic Conditions, David L. Freedman, James M. Gossett Sep 1989

Biological Reductive Dechlorination Of Tetrachloroethylene And Trichloroethylene To Ethylene Under Methanogenic Conditions, David L. Freedman, James M. Gossett

Publications

A biological process for remediation of groundwater contaminated with tetrachloroethylene (PCE) and trichloroethylene (TCE) can only be applied if the transformation products are environmentally acceptable. Studies with enrichment cultures of PCE- and TCE-degrading microorganisms provide evidence that, under methanogenic conditions, mixed cultures are able to completely dechlorinate PCE and TCE to ethylene, a product which is environmentally acceptable. Radiotracer studies with [14C]PCE indicated that [14C]ethylene was the terminal product; significant conversion to 14CO2 or 14CH4 was not observed. The rate-limiting step in the pathway appeared to be conversion of vinyl chloride to ethylene. To sustain reductive dechlorination of ...


Effects Of Eddy Viscosity And Thermal Conduction And Coriolis Force In The Dynamics Of Gravity Wave Driven Fluctuations In The Oh Nightglow, Michael P. Hickey Ph.D. May 1988

Effects Of Eddy Viscosity And Thermal Conduction And Coriolis Force In The Dynamics Of Gravity Wave Driven Fluctuations In The Oh Nightglow, Michael P. Hickey Ph.D.

Publications

Recently, Walterscheid et al. (1987) have described a dynamical-chemical model of wave-driven fluctuations in the OH nightglow which incorporated a five-reaction photochemical scheme and the dynamics of linearized acoustic-gravity waves in an isothermal, motionless atmosphere. The intensity oscillation (δI) about the time-averaged intensity (I0) and the temperature oscillation (δT) about the time-averaged temperature (T0) were related by means of the complex ratio η ≡ (δI/I0)/(δT/T0). One of the main conclusions of their work was that the inclusion of dynamical effects is absolutely essential for a valid assessment of η at ...


Wavelength Dependence Of Eddy Dissipation And Coriolis Force In The Dynamics Of Gravity Wave Driven Fluctuations In The Oh Nightglow, Michael P. Hickey Ph.D. May 1988

Wavelength Dependence Of Eddy Dissipation And Coriolis Force In The Dynamics Of Gravity Wave Driven Fluctuations In The Oh Nightglow, Michael P. Hickey Ph.D.

Publications

The theory of Walterscheid et al. (1987) to explain internal gravity wave induced oscillations in the emission intensity I and rotational temperature T of the OH nightglow was modified by Hickey (1988) to include the effects of eddy dissipation and Coriolis force. In the theory of Walterscheid et al. (1987) the ratio η = (δI/I0)/(δT/T0) (δ refers to a perturbation quantity, and a zero subscript refers to an average) was found to be independent of horizontal wavelength at long periods, while in the extended theory of Hickey (1988) some such dependence was inferred. In ...


Earth Observing System, Volume Iia: Data And Information System, Report Of The Eos Data Panel, Raymond Arvidson, Frederick Billingsley, Robert Chase, Pat Chavez Jr., Michael Devirian, Frederick Mosher, Et Al. Jan 1986

Earth Observing System, Volume Iia: Data And Information System, Report Of The Eos Data Panel, Raymond Arvidson, Frederick Billingsley, Robert Chase, Pat Chavez Jr., Michael Devirian, Frederick Mosher, Et Al.

Publications

The purpose of this report is to provide NASA with a rationale and recommendations for planning, implementing, and operating an Earth Observing System data and information system that can evolve to meet the Earth Observing System's needs in the 1990s. The Earth Observing System (EOS), defined by the EOS Science and Mission Requirements Working Group, consists of a suite of instruments in low Earth orbit acquiring measurements of the Earth's atmosphere, surface, and interior; an information system to support scientific research; and a vigorous program of scientific research, stressing study of global-scale processes that shape and influence the ...


Periods Of Eo And Fv Comae Berenices And The Functional Forms Of Their O-C Diagrams, Mark Anthony Reynolds Jan 1986

Periods Of Eo And Fv Comae Berenices And The Functional Forms Of Their O-C Diagrams, Mark Anthony Reynolds

Publications

New elements are given for the RRab Lyrae variables EO Comae Berenices and FV Comae Berenices. The statistical significance of higher order terms in a polynomial least squares fit is discussed.


The Frontal Hydraulic Head: A Micro-Α Scale (~1 Km) Triggering Mechanism For Mesoconvective Weather Systems, M. A. Shapiro, Tamara Hampel, Doris Rotzoll, F. Mosher Jul 1985

The Frontal Hydraulic Head: A Micro-Α Scale (~1 Km) Triggering Mechanism For Mesoconvective Weather Systems, M. A. Shapiro, Tamara Hampel, Doris Rotzoll, F. Mosher

Publications

Measurements from the NOAA Boulder Atmospheric Observatory (BAO) 300 m tower, the National Center for Atmospheric Research (NCAR) Sabreliner aircraft, and the NOAA GOES-5 satellite, give evidence for the cross-front scale collapse of nonprecipitating surface cold-frontal zones to horizontal distances of ∼1 km or less. The leading edges of these frosts possess the characteristic structure of density current flows: an elevated hydraulic head followed by a turbulent wake. Vertical motions at the frontal heads exceed 5 m s−1 at 300 m (AGL). The ascent at the frontal head may act as a (∼1 km-scale) triggering mechanism for the release ...


Impacts Of Interactive Processing Systems On The Forecasting Ability Of The National Severe Storms Forecast Center (Appendix E), Frederick R. Mosher Apr 1985

Impacts Of Interactive Processing Systems On The Forecasting Ability Of The National Severe Storms Forecast Center (Appendix E), Frederick R. Mosher

Publications

The National Severe Storms Forecast Center (NSSFC) in Kansas City has the most modern interactive processing equipment of any operational forecast office in the United States. As such, the experiences of the NSSFC serve as the indication of some of the benefits which will be derived from interactive technology when it is applied in other forecast situations. The forecast products issued by the NSSFC have become more accurate and more timely. The forecaster's efficiency and productivity has noticeably improved. These improvements have been made without the introduction of any new data sources, any major advances in meteorology, or any ...


Functional And Performance Requirements Of The Next Noaa-Kansas City Computer System (Appendix G), Frederick R. Mosher Apr 1985

Functional And Performance Requirements Of The Next Noaa-Kansas City Computer System (Appendix G), Frederick R. Mosher

Publications

The NOAA computer system in Kansas City, Missouri, was scheduled for a computer upgrade and this is part of the report listing the critical functional and performance requirements for that system in 1984. The system needed to communicate with all the other offices at that center in Kansas City.


Lessons Learned From The Csis [Centralized Storm Information System] (Appendix D), Frederick R. Mosher, Joseph T. Schaefer Apr 1985

Lessons Learned From The Csis [Centralized Storm Information System] (Appendix D), Frederick R. Mosher, Joseph T. Schaefer

Publications

Various attempts have been made to give up-to-the-minute meteorological observations to forecasters. However, the meteorologist's inability to assimilate all the real-time data is a significant barrier to the improvement of short-term forecasts and warnings. Historically, failure to resolve this problem has plagued mesoscale forecast experiments. This article discusses the joint effort of NWS, NESS, NASA, and SSEC to develop a system to aid the forecaster in evaluating data.


Characteristics Of Water Vapor Tracked Winds, Frederick R. Mosher Aug 1981

Characteristics Of Water Vapor Tracked Winds, Frederick R. Mosher

Publications

Wind measurements were obtained by tracking water vapor features on Meteosat and GOES-VAS 6.7 micron water vapor images. While pure water vapor features are fuzzy, there are discernible features which can be tracked. An investigation of preprocessing algorithms designed to bring out the features to be tracked showed that high pass filters tended to bring out the noise in the image, while low pass filters washed out the features. Sliced linear gray scale stretching under operator control gave the best enhancement to the water vapor features.


Meteorological Significance Of Cloud Tracked Winds During Dst-5 And Dst-6, H. M. Goodman, Frederick Mosher, Tod Stewart, Verner Suomi Jul 1981

Meteorological Significance Of Cloud Tracked Winds During Dst-5 And Dst-6, H. M. Goodman, Frederick Mosher, Tod Stewart, Verner Suomi

Publications

A study has been conducted to determine the meteorological significance of satellite derived cloud drift winds using data from the Data Systems Test (DST). Three synoptic weather events were chosen during DST-6 (January 5-March 5) for weather analysis and comparison. The three events each contained a prominent weather feature over the north Pacific Ocean. Two satellite sources (NESS and the University of Wisconsin), radiosonde and commercial aircraft reports combined to produce a wind set covering the target area.


A Model For Calculating Desert Aerosol Turbidity Over The Oceans From Geostationary Satellite Data, Carl C. Norton, Frederick R. Mosher, Barry Hinton, David W. Martin, David Santek, William Kuhlow Jun 1980

A Model For Calculating Desert Aerosol Turbidity Over The Oceans From Geostationary Satellite Data, Carl C. Norton, Frederick R. Mosher, Barry Hinton, David W. Martin, David Santek, William Kuhlow

Publications

A technique has been developed to infer the optical thickness of Saharan dust from Synchronous Meteorological Satellite (SMS) brightness measurements at visible wavelengths. The scattering model consists of an air layer, a dust layer and a lower boundary of variable albedo. Single-scatter properties of the dust computed from Mie theory were the basis for calculations by plane-parallel theory of radiative transfer in the dust layer. Radiative interactions between air and dust layers and the lower boundary were calculated with an adding version of the doubling scheme. Optical thickness was determined from satellite brightness measurements through a lookup table produced by ...


Shallow Convection On Day 261 Of Gate: Mesoscale Arcs, C. Warner, J. Simpson, D. W. Martin, D. Suchman, F. R. Mosher, R. F. Reinking Dec 1979

Shallow Convection On Day 261 Of Gate: Mesoscale Arcs, C. Warner, J. Simpson, D. W. Martin, D. Suchman, F. R. Mosher, R. F. Reinking

Publications

On 18 September 1974, a cloud cluster growing in the GATE [Global Atmospheric Research Program] ship array was examined using aircraft flying close to one another at different heights, the geostationary satellite SMS-1, and radar, rawinsonde and ship data, with a view to elucidating mechanisms of convection. In this paper we concentrate analysis on cloudy convection in the moist layer.

In and above southerly surface monsoon flow approaching the cluster, clouds indigenous to the moist layer took the form of rows of tiny cumulus, and of arcs of cumulus mediocris, with patterns different from those of deeper clouds. From satellite ...


An Investigation Of Surface Albedo Variations During The Recent Sahel Drought, Carl C. Norton, Frederick R. Mosher, Barry Hinton Oct 1979

An Investigation Of Surface Albedo Variations During The Recent Sahel Drought, Carl C. Norton, Frederick R. Mosher, Barry Hinton

Publications

Applications Technology Satellite (ATS) 3 green sensor data are used to measure surface reflectance variations in the Sahara/Sahel during the recent drought period 1967–74. The magnitude of the seasonal reflectance change is shown to be as much as 80% for years of normal precipitation and less than 50% for drought years. Year-to-year comparisons during both wet and dry seasons reveal the existence of a surface reflectance cycle coincident with the drought intensity. The relationship between the green reflectance and solar albedo is examined and estimated to be about 0.6 times the reflectance change observed by the green ...


Ca Ii H And K And Hydrogen-Line Variations In V471 Tauri (=Bd + 16°516), Terry D. Oswalt Apr 1979

Ca Ii H And K And Hydrogen-Line Variations In V471 Tauri (=Bd + 16°516), Terry D. Oswalt

Publications

Spectroscopic and narrow-band photoelectric observations of the white dwarf eclipsing binary V471 Tau (= BD + 16°516) are reported. Periodic fluctuations in Ca IIH and K emission and Ha absorption, and a wave-like distortion of the light curve mimic the characteristics of several well-observed RS CVn binaries. A probable correlation between maximum emission-line strength and wave minimum is shown to exist.