Engineering topics

Staylor, W. F.

Publications and source records attributed to Staylor, W. F..

At least 19 records

NASA NTRS1995

First global WCRP shortwave surface radiation budget dataset

Shortwave radiative fluxes that reach the earth's surface are key factors that influence atmospheric and oceanic circulations as well as surface climate. Yet, information on these fluxes is meager. Surface site data are generally available from only a limited number of observing stations over land. Much less is known about the large-scale variability of the shortwave radiative fluxes over the oceans, which cover most of the globe. Recognizing the need to produce global-scale fields of such fluxes for use in climate research, the World Climate Research Program has initiated activities that led to the establishment of the Surface Radiation Budget Climatology Project with the ultimate goal to determine various components of the surface radiation budget from satellite data. In this paper, the first global products that resulted from this activity are described. Monthly and daily data on a 280-km grid scale are available. Samples of climate parameters obtainable from the dataset are presented. Emphasis is given to validation and limitations of the results. For most of the globe, satellite estimates have bias values between +/- 20 W/sq m and root mean square (rms) values are around 25 W/sq m. There are specific regions with much larger uncertainties however.

Whitlock, C. H.↗

NASA NTRS1995

First global WCRP shortwave surface radiation budget dataset

Shortwave radiative fluxes that reach the Earth's surface are key factors that influence atmospheric and oceanic circulations as well as surface climate. Yet, information on these fluxes is meager. Surface site data are generally available from only a limited number of observing stations over land. Much less is known about the large-scale variability of the shortwave radiative fluxes over the oceans, which cover most of the globe. Recognizing the need to produce global-scale fields of such fluxes for use in climate research, the World Climate Research Program has initiated activities that led to the establishment of the Surface Radiation Budget Climatology Project with the ultimate goal to determine various components of the surface radiation budget from satellite data. In this paper, the first global products that resulted from this activity are described. Monthly and daily data on a 280-km grid scale are available. Samples of climate parameters obtainable from the dataset are presented. Emphasis is given to validation and limitations of the results. For most of the globe, satellite estimates have bias values between +/- 20 W/sq m and rms values are around 25 W/sq m. There are specific regions with much larger uncertainties however.

Whitlock, C. H.↗

NASA NTRS1993

WCRP surface radiation budget shortwave data product description, version 1.1

Shortwave radiative fluxes which reach the Earth's surface are key elements that influence both atmospheric and oceanic circulation. The World Climate Research Program has established the Surface Radiation Budget climatology project with the ultimate goal of determining the various components of the surface radiation budget from satellite data on a global scale. This report describes the first global product that is being produced and archived as part of that effort. The interested user can obtain the monthly global data sets free of charge using e-mail procedures.

Whitlock, C. H.↗

NASA NTRS1992

Seasonal variation of surface radiation budget derived from International Satellite Cloud Climatology Project C1 data

Surface radiation budget data are presented for the midseasonal months of July and October of 1983 and January and April of 1984. These data allow the examination of geographical and seasonal variations of the entire surface radiation budget from pole to pole. The latest flux estimation techniques have been used along with data from the International Satellite Cloud Climatology Project and the Earth Radiation Budget Experiment. Regional, zonal, and hemispheric distributions of the downward and net components of both shortwave and longwave fluxes and of the net total surface fluxes are determined. Seasonal flux variation per region, expressed as flux range, is illustrated for these components also. The estimated fluxes appear to be accurate to about 16 W/sq m on a global average, based on sensitivity analyses and comparisons with ground data. An analysis of flux errors showed that most of the error was attributable to errors in input data.

Darnell, Wayne L.↗

NASA NTRS1990

AVHRR and VISSR satellite instrument calibration results for both Cirrus and marine stratocumulus IFO periods

Accurate characterizations of some cloud parameters are dependent upon the absolute accuracy of satellite radiance measurements. Visible wavelength measurements from both the AVHRR and VISSR instruments are often used to study cloud characteristics. Both of these instruments were radiometrically calibrated prior to launch, but neither has an onboard device to monitor degradation after launch. During the FIRE/SRB cirrus Intensive Field Operation (IFO), a special effort was made to monitor calibration of these two instruments onboard the NOAA-9 and GOES-6 spacecraft. In addition, several research groups have combined their efforts to assess the long-term performance of both instruments. These results are presented, and a limited comparison is made with the ERBE calibration standard.

Whitlock, C. H.↗

NASA NTRS1990

Surface radiation budget - Current perspective

The surface radiation budget of the earth is important in climate research because it gives an understanding of the distribution of solar and IR radiation exchanges at the surface. Data on the distribution and exchange of these surface radiations are needed over the entire earth on a long-term basis. Global satellite data, coupled with highly developed models, now provide estimates of the surface radiation budget which are near the accuracy required for climate research. A description of surface radiation research, its current state, and planned programs are presented.

Darnell, Wayne L.↗

NASA NTRS1990

Global surface albedos estimated from ERBE data

The earth radiation budget experiment (ERBE) has allowed the most accurate measurement of broadband, top-of-the-atmosphere albedos ever produced on a regional/global basis. These ERBE albedos, combined with the Koepke and Kriebel model and appropriate atmospheric parameters, are employed to estimate global surface albedos for several periods in 1985 and January 1986.

Staylor, W. F.↗

NASA NTRS1990

Comparison of Surface Radiation Budget Satellite algorithms for downwelled shortwave irradiance with Wisconsin Fire/SRB surface-truth data

Surface radiation instruments were operated at various locations during the Wisconsin First ISSCP (International Satellite Cloud Climatology Project) Regional Experiment (FIRE) and Surface Radiation Budget (SRB) experiment in October 1986. Satellite data were distributed to scientists who had previously developed satellite algorithms to estimate downwelled shortwave irradiance. Results of intercomparison of ground-truth values with the satellite-derived estimates are described.

Whitlock, C. H.↗

NASA NTRS1990

Global correlations for surface radiation studies

This study demonstrates a strong correlation between surface absorbed shortwave flux and top-of-the-atmosphere net shortwave flux. This technique permits determination of absorbed shortwave radiation at the surface without knowledge of the surface albedo.

Wilber, Anne C.↗

NASA NTRS1990

Sensitivity of surface radiative fluxes to meteorological parameter errors

A parameterized radiative transfer model is employed to estimate longwave fluxes, while shortwave fluxes are estimated with a broadband absorption and scattering technique. Meteorological parameters of surface radiative fluxes are the profiles of temperature and cloud cover, ozone, water vapor and aerosols. A sensitivity study is presented to estimate the magnitudes of biases in the computed fluxes resulting from the biases in the satellite meteorological data.

Ritchey, Nancy A.↗

NASA NTRS1990

Global surface radiation flux results for all seasons using ISCCP-C1 data

Algorithms have been developed at the Langley Research Center to estimate fluxes for all of the surface radiation components utilizing the new International Satellite Cloud Climatology Project (ISSCP) C1 data and grid system. These surface radiation budget data are the first all-component flux set encompassing the entire globe, based on satellite-derived C1 meteorological data. A description of the input data and the algorithms utilized, examples of the global flux results, discussion of how the current fluxes compare with ground-truth fluxes, and remarks on errors in the current flux estimates are presented.

Darnell, Wayne L.↗

NASA NTRS1988

Angular radiation models for Earth-atmosphere system. Volume 1: Shortwave radiation

Presented are shortwave angular radiation models which are required for analysis of satellite measurements of Earth radiation, such as those fro the Earth Radiation Budget Experiment (ERBE). The models consist of both bidirectional and directional parameters. The bidirectional parameters are anisotropic function, standard deviation of mean radiance, and shortwave-longwave radiance correlation coefficient. The directional parameters are mean albedo as a function of Sun zenith angle and mean albedo normalized to overhead Sun. Derivation of these models from the Nimbus 7 ERB (Earth Radiation Budget) and Geostationary Operational Environmental Satellite (GOES) data sets is described. Tabulated values and computer-generated plots are included for the bidirectional and directional modes.

Suttles, J. T.↗

NASA NTRS1986

Downward longwave surface radiation from sun-synchronous satellite data - Validation of methodology

An extensive study has been carried out to validate a satellite technique for estimating downward longwave radiation at the surface. The technique, mostly developed earlier, uses operational sun-synchronous satellite data and a radiative transfer model to provide the surface flux estimates. The satellite-derived fluxes were compared directly with corresponding ground-measured fluxes at four different sites in the United States for a common one-year period. This provided a study of seasonal variations as well as a diversity of meteorological conditions. Dome heating errors in the ground-measured fluxes were also investigated and were corrected prior to the comparisons. Comparison of the monthly averaged fluxes from the satellite and ground sources for all four sites for the entire year showed a correlation coefficient of 0.98 and a standard error of estimate of 10 W/sq m. A brief description of the technique is provided, and the results validating the technique are presented.

Darnell, W. L.↗

NASA NTRS1986

Site selection and directional models of deserts used for ERBE validation targets

Broadband shortwave and longwave radiance measurements obtained from the Nimbus 7 Earth Radiation Budget scanner were used to develop reflectance and emittance models for the Sahara, Gibson, and Saudi Deserts. These deserts will serve as in-flight validation targets for the Earth Radiation Budget Experiment being flown on the Earth Radiation Budget Satellite and two National Oceanic and Atmospheric Administration polar satellites. The directional reflectance model derived for the deserts was a function of the sum and product of the cosines of the solar and viewing zenith angles, and thus reciprocity existed between these zenith angles. The emittance model was related by a power law of the cosine of the viewing zenith angle.

Staylor, W. F.↗

NASA NTRS1986

Reflection and emission models for deserts derived from Nimbus-7 ERB scanner measurements

Broadband shortwave and longwave radiance measurements obtained from the Nimbus-7 Earth Radiation Budget scanner were used to develop reflectance and emittance models for the Sahara-Arabian, Gibson, and Saudi Deserts. The models were established by fitting the satellite measurements to analytic functions. For the shortwave, the model function is based on an approximate solution to the radiative transfer equation. The bidirectional-reflectance function was obtained from a single-scattering approximation with a Rayleigh-like phase function. The directional-reflectance model followed from integration of the bidirectional model and is a function of the sum and product of cosine solar and viewing zenith angles, thus satisfying reciprocity between these angles. The emittance model was based on a simple power-law of cosine viewing zenith angle.

Staylor, W. F.↗

NASA NTRS1985

Reflection and emission models for clouds derived from Nimbus 7 earth radiation budget scanner measurements

Statistical results from 2.8 million pairs of broadband shortwave and longwave radiance measurements were used to develop reflectance and emittance models for low, middle, and high water clouds and high ice clouds. The reflectance model was a function of the sum and product of the cosine of solar and viewing zenith angles, and the emittance model was related by a power law of the cosine of the viewing zenith angle.

Staylor, W. F.↗

NASA NTRS1983

Downward longwave radiation at the surface from satellite measurements

A new technique is presented for generating downward longwave flux at the earth's surface from satellite meteorological data and a radiative transfer model. The technique was tested by using TIROS-N data from 41 passes over a ground site covering a period of one month. Satellite-derived fluxes were compared with those measured by a ground-based pyrgeometer during each overpass. The standard error of the satellite-derived fluxes relative to the mean ground-measured values was found to be 6.5 percent.

Darnell, W. L.↗

NASA NTRS1983

A parameterization for downward longwave radiation from satellite meteorological data

An accurate and efficient parameterization is developed which computes clear-atmosphere downward longwave flux in terms of the water vapor burden and water-vapor-weighted average temperature of the surface-700 mb region. The parameterization is based on detailed radiative transfer calculations performed for a wide meteorological data base, consisting of 180 atmospheric models generated from climatological data and 106 radiosonde-measured models. The standard error of the computed fluxes was found to be about 4 percent of the mean value. It is also pointed out that strong heating or cooling of the surface, as shown by many TOVS data sets, caused larger errors in the computed fluxes.

Gupta, S. K.↗