An Examination of a Technique for Estimating the Longwave Radiation Budget from Satellite Radiance Observations

Abstract

Comparisons of zonally averaged outgoing longwave fluxes estimated from 10 ?m radiance observations on NOAA polar orbiting satellites with flat plate observations on the Nimbus 6 ERB experiment have shown the NOAA estimates to be systematically larger than the ERB data. The NOAA flux estimation technique has been examined with the use of a new radiative transfer model and with several new assumptions concerning the properties of clouds in the field of view of the satellite to determine if there are situations which will lead to such differences. The analysis indicates that the operational estimation technique overestimates fluxes for middle and high cloud conditions. The use of new assumptions concerning the cloud cover and the use of a radiation model different from that used in the initial study will reduce the NOAA-ERB flux differences by approximately 30%.