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  • Author or Editor: Lee M. Avis x
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Richard N. Green
and
Lee M. Avis

Abstract

The earth radiation budget satellite (ERBS) has made broadband scanner measurements of the earth radiance for over 5 years. The redundancy between the shortwave, longwave, and total scanning radiometers and data averages have been used to validate the long-term consistency among the measurements and to establish how measurement drift has affected the archived top-of-the-atmosphere fluxes. The total channel gain at night was found to be unchanged over a 4-yr test period. Relative to the total channel at night, the longwave channel sensitivity decreased by 0.5% over the same 4 years and the shortwave channel was unchanged. The shortwave part of the total channel, however, gradually increased in gain by 1.3%. Only the daytime longwave flux was affected by these changes. It drifted upward depending on the scene shortwave component. Over 4 years, the clear ocean daytime longwave flux increased by 0.2% and overcast scenes by 2.6%. For all scenes in the Tropics, the daytime longwave flux increased by less than 1% in 4 years. There was no statistical evidence that the daytime shortwave or nighttime longwave fluxes had drifted.

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G. Louis Smith
,
Natividad Manalo-Smith
, and
Lee M. Avis

Abstract

During January and August 1985, the scanning radiometers of the Earth Radiation Budget Experiment (F-RBE) aboard the Earth Radiation Budget Satellite (ERBS) and the NOAA-9 satellite were operated in along- track scanning modes. Along-track scanning permits the study of many measurement problems. It provides the data for developing a limb-darkening model for a single site over a short period of time and also permits the identification of the scene from data taken at small nadir angles. The earth-emitted radiation measured by the scanners has been analyzed to produce limb-darkening models for a variety of scene types. Limb-darkening models relate the radiance in any given direction to the radiant flux. The scene types were computed using measurements within 1O° of zenith. The models have values near zenith of 1.02–1.09. The typical zenith values of the model are 1.06 for both day and night for FRBS, and for NOAA-9, 1.06 for day and 1.05 for night. Mean models are formed for the ERBS and NOAA-9 results and are found to differ less than 1%, the ERBS results being the higher. The models vary about 1% with latitude near zenith and agree with earlier models that were used to analyze ERBE data typically to 2%.

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