The mixture problem in computer mapping of terrain: Improved techniques for establishing spectral signatures, atmospheric path radiance, and transmittance
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Smedes, H. W.↗
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Laboratory and field measurements of upwelled radiance and reflectance spectra of suspended James River sediments near Hopewell, Virginia
Spectral reflectance characteristics of suspended Bermuda Hundred and Bailey Bay bottom sediments taken from the Hopewell, Va., area were measured in the laboratory for water mixture total suspended solids concentrations between 4 and 173 parts per million. Field spectral reflectance measurements were made of the James River waters near Bermuda Hundred on two occasions. The results of these tests indicate that both Bermuda Hundred and Bailey Bay suspended sediments produce their strongest reflectance in the green and red regions of the spectrum.
Whilock, C. H.↗
Application of meteorological satellite visible channel radiances for determining solar radiation reaching the ground
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Ellis, J. S.↗
Ozone abundances in the lower mesosphere deduced from backscattered solar radiances
Backscatter ultraviolet data obtained by the Explorer E satellite imply very large ozone column abundances above 56 km in the tropics during mid-day. The number of molecules in a vertical column decays by a factor of 2-3 after the solar zenith angle exceeds 75 deg in the evening. An increase of similar magnitude occurs after sunrise. Such behavior implies the presence of a greater source of odd oxygen than is included in current photochemical theories. Ozone profiles deduced between altitudes of 50 and 62 km when the solar zenith angle exceeds 80 deg are in reasonable agreement with past rocket results.
Frederick, J. E.↗
Effect of aerosols on the estimation of total ozone in an atmospheric column from the measurements of its ultraviolet radiance
The problem of estimating the total ozone amount of an atmospheric column in the presence of stratospheric and tropospheric aerosols is studied by means of simulated spectral measurements for the five-wavelength Nimbus 4 BUV configuration and the six-wavelength Nimbus G TOMS configuration, and by analyzing such measurements with appropriate total ozone estimation procedures. The simulated spectral measurements were generated for forty different atmospheric models arrived at by varying the total ozone content and various aerosol parameters. A total of ten different values of the solar zenith angle and eight different values of the Lambert reflectivity of the underlying surface were used. It was found that the values of total ozone in an atmospheric column estimated by the five-wavelength procedure can be in error by about + or -2% as a result of particulate contamination encountered in the terrestrial atmosphere under average conditions. Errors due to tropospheric particulate contamination can be reduced significantly by taking appropriate advantage of the additional spectral measurement offered by the Nimbus G TOMS instrument.
Dave, J. V.↗
Comparison between photographic and photoelectric measurements of the solar aureole almucantar radiance
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Deepak, A.↗
Relationship of red and photographic infrared spectral radiances to alfalfa biomass, forage water content, percentage canopy cover, and severity of drought stress
Red and photographic infrared spectral data were collected using a handheld radiometer for two cuttings of alfalfa. Significant linear and non-linear correlation coefficients were found between the spectral variables and plant height, biomass, forage water content, and estimated canopy cover for the earlier alfalfa cutting. The alfalfa of later cutting experienced a period of severe drought stress which limited growth. The spectral variables were found to be highly correlated with the estimated drought scores for this alfalfa cutting.
Tucker, C. J.↗
Image contrast of diffraction-limited telescopes for circular incoherent sources of uniform radiance
A simple approximate formula is derived for the background intensity beyond the edge of the image of uniform incoherent circular light source relative to the irradiance near the center of the image. The analysis applies to diffraction-limited telescopes with or without central beam obscuration due to a secondary mirror. Scattering off optical surfaces is neglected. The analysis is expected to be most applicable to spaceborne IR telescopes, for which diffraction can be the major source of off-axis response.
Shackleford, W. L.↗
Relationship of crop radiance to alfalfa agronomic values
Red and photographic infrared spectral data of alfalfa were collected at the time of the third and fourth cuttings using a hand-held radiometer for the earlier alfalfa cutting. Significant linear and non-linear correlation coefficients were found between the spectral variables and plant height, biomass, forage water content, and estimated canopy cover. For the alfalfa of the later cutting, which had experienced a period of severe drought stress which limited growth, the spectral variables were found to be highly correlated with the estimated drought scores.
Tucker, C. J.↗
Multispectral Resource Sampler (MRS): Proof of concept. Study on bidirectional reflectance. A simulation analysis of bidirectional reflectance properties and their effects on scene radiance. Implications for the MRS
A study was performed to evaluate the geometrical implication of a Multispectral Resource Sampler; a pointable sensor. Several vegetative targets representative of natural and agricultural canopies were considered in two wavelength bands. All combinations of Sun and view angles between 5 and 85 degrees zenith for a range of azimuths were simulated to examine geometrical dependance arising from seasonal as well as latitudinal variation. The effects of three different atmospheres corresponding to clear, medium and heavy haze conditions are included. An extensive model data base was generated to provide investigators with means for possible further study of atmospheric correction procedures and sensor design questions.
Smith, J. A.↗
Ozone profiling from backscattered UV radiance measurements A new procedure
This paper presents a data analysis technique that has been developed to support a stratospheric ozone measurement and profiling program. The data consist of solar backscattered UV radiation monitored by a spacecraft. The output consists of ozone mixing ratio profiles complete with error bars throughout the atmosphere. The technique is based upon principles of nonlinear optimal estimation. It provides a number of desirable features that have not been available together in any previously constructed technique for the problem. Iteration on both radiation measurements and total ozone measurements is among these features.
Whitney, C. K.↗
Retrieval and use of high-resolution moisture and stability fields from Nimbus 6 HIRS radiances in pre-convective situations
A moisture-temperature retrieval scheme was developed for lower-tropospheric analysis and forecasting parameters from the Nimbus 6 High-resolution Infrared Radiation Sounder, in a study of convective development on the Great Plains of the U.S. on four case study days in August 1975. Dew points and temperatures, along with such secondary parameters as total precipitate water and static stability indices, were derived and analyzed at a horizontal resolution of up to 30 km on the four days. Convective development beginning 2.0-2.5 hours after the satellite pass at local noon was found to correlate well with local moisture and instability maxima seen in the satellite-derived analyses. A statistical structure analysis of the satellite-derived parameters gave the highest signal-to-noise values for the moisture and stability parameters, while the temperature parameters showed much lower signal-to-noise content.
Hillger, D. W.↗
Determination of semi-transparent cirrus cloud temperature from infrared radiances - Application to Meteosat
A bispectral technique was employed to determine the cirrus cloud-top temperature. Data were gathered from aircraft equipped with the ARIES radiometer, which on sixteen flights provided IR readings at 6.5 and 11.5 microns of cirrus tops. The flights were made on a NASA Convair to a maximum ceiling of 12,500 m. The brightness temperatures above the cirrus were found to be consistently colder, by up to 40 K, than the 11.5 microns window channel, and good spatial correlations were displayed over whole clouds. Effective emissivities are calculated for both channels and applied to Meteosat digital imagery. The subsequent derived temperatures were significantly colder than black-body temperatures, which is explained by taking into account the absorption of emitted radiation by water vapor.
Szejwach, G.↗
Effect of forest canopy closure on incoming solar radiance
(Previously announced in STAR as N81-28499)
Dottavio, C. L.↗
Derivation of sea ice concentration, age and surface temperature from multispectral microwave radiances obtained with the Nimbus-7 scanning multichannel microwave radiometer
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Gloersen, P.↗
The DMSP/MFR total ozone and radiance data base
This report describes the entries in sufficient detail so that the data base might be useful to others. The characteristics of the MFR sensor are briefly discussed and a complete index to the data base tapes is given.
Ellis, J. S.↗
A Hand Held Ratioing Radiometer for remote radiance measurements
The small, lightweight Hand Held Ratioing Radiometer (HHRR) measures the ratio of spectral reflectance in any of 25 pairs of narrow bands in the 400 to 2500 nanometer spectral region. Two parallel optical trains view the scene through separate filters mounted in two filter wheels each containing five filters. Absolute reflectance of the scene can also be measured. HHRR is particularly useful for ground truth studies for the interpretation of imagery from Landsat, the thematic mappers and the forthcoming SPOT satellite. Its small size and simplicity of operation make it useful to geologists, botanists, oceanographers and many other geotechnologists.
Daubner, L.↗
Quantitative interpretation of cloud radiances observed with a 94 GHz scanning radiometer
A description is presented of the results of a theoretical study to evaluate the remote sensing technique to determine integrated liquid water content. The considered technique uses 94 GHz passive microwave observations as applied to nonprecipitation clouds over the ocean. The study indicates that it is possible to infer the precipitable water of the atmosphere with a useful accuracy from a single 94 GHz nadir measurement and an estimated sea surface temperature. It is demonstrated that the integrated liquid water content of nonprecipitable clouds can be estimated with a relative accuracy of 20% to 30% depending on the atmospheric water vapor content from a microwave passive measurement at 94 GHz in the presence of clouds and in cloud free areas in the vicinity of the cloud in conjunction with information on the sea surface and cloud top temperatures.
Szejwach, G.↗