The Interpretation of Remotely Sensed High Cloud Emittances

Abstract

The scattering and reflection components of the remotely measured effective beam emittance of high clouds are calculated using a detailed model of radiative transfer through cirrus. Two atmospheric profiles of temperature and humidity are used representing tropical and midlatitude summer atmospheres respectively. The scattering and reflection components of the measured beam emittance are shown to be appreciable, particularly for tropical atmospheres where for example the reflection component at the ground for vertical viewing is 20% of the total emittance. Computed values of the broad-band effective flux emittance are compared with equivalent values of the narrow-band effective flux emittance at 11 ?m wavelength and the narrow-band beam emittance at 11?m. It is shown that the two former quantities are well correlated and approximately equal in magnitude.