PRELIMINARY RESULTS OF RADIATION MEASUREMENTS FROM THE TIROS III METEOROLOGICAL SATELLITE

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  • 1 Goddard Space Flight Center, Greenbelt, Maryland
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Abstract

Three simple and typical cases of radiation fluxes measured by the TIROS III meteorological satellite are presented and discussed. These cases deal with emitted earth radiation received in three infrared channels and reflected solar radiation received in two visible channels over the tropical Atlantic, the eastern United States, and the North African desert. Each of the measurements is accompanied by results from a wide-field radiometer and photographs from TV cameras flown in the same satellite. The cases over the Atlantic Ocean and the African desert were in almost cloudless sides, while the case over the United States included regions ranging from heavily clouded to clear. Results show that the measurements from the various instruments and in the various channels are internally consistent. Maximum albedo values over the overcast arms were determined to be approximately 55 per cent. Over the ocean, albedos were near 7 per cent, and over land and clear skies the albedo varied from about 15 per cent over heavy vegetation to about 30 per cent over the desert. From these measurements total outgoing energy fluxes in the infrared were computed to be as high as 340 watts per square meter over the desert and as low as 190 watts per square meter over the cloudy areas. With the exception of the measurements made over the desert, results in the atmospheric window channel (7.5 to 13.5 microns) show substantial absorption, probably due to water vapor.

Abstract

Three simple and typical cases of radiation fluxes measured by the TIROS III meteorological satellite are presented and discussed. These cases deal with emitted earth radiation received in three infrared channels and reflected solar radiation received in two visible channels over the tropical Atlantic, the eastern United States, and the North African desert. Each of the measurements is accompanied by results from a wide-field radiometer and photographs from TV cameras flown in the same satellite. The cases over the Atlantic Ocean and the African desert were in almost cloudless sides, while the case over the United States included regions ranging from heavily clouded to clear. Results show that the measurements from the various instruments and in the various channels are internally consistent. Maximum albedo values over the overcast arms were determined to be approximately 55 per cent. Over the ocean, albedos were near 7 per cent, and over land and clear skies the albedo varied from about 15 per cent over heavy vegetation to about 30 per cent over the desert. From these measurements total outgoing energy fluxes in the infrared were computed to be as high as 340 watts per square meter over the desert and as low as 190 watts per square meter over the cloudy areas. With the exception of the measurements made over the desert, results in the atmospheric window channel (7.5 to 13.5 microns) show substantial absorption, probably due to water vapor.

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