Airborne Radiometer Measurements of Effects of Particulates on Terrestrial Flux

Abstract

Thin layers of particulates or clouds in the high troposphere and lower stratosphere are generally not visible to an observer at the surface, even under the favorable viewing conditions at sunset. They are not easily detected by a television camera in a satellite from above. Yet these layers affect upwelling infrared flux. A flight program, employing balloon-borne radiometers and a jet aircraft from which visual observations of particle layers were made, was conducted to measure the attenuating effects of these layers on upwelling. terrestrial flux. An estimate of the error such attenuation can cause in surface temperatures deduced from the upward flux measurement was then made. The balloon-borne radiometers were launched from a desert area of California. During the ascents the presence of cirrus or particle layers could not he visually or photographically detected from the surface. They were, however, detected by the radiometer during ascent and by observers in a jet aircraft. The observations indicated an attenuation in upward infrared flux as a result of an observed particle layer beneath the higher balloon-home measurements. This attenuation could cause a 5.0C surface temperature estimate error. Several similar observations and calculations without observers aloft show the same result.