Abstract

The SSH-2 infrared sounder aboard the DMSP satellite contains eight water vapor sounding channels: seven in the 18 µm - 28 µm region and one centered around 12.5 µm. The central frequencies of these channels and their spectral bandwidths¹ are shown in Table 1. The information content, i.e.: the relative contribution to the measured radiance from different atmospheric layers, of the water vapor sounding channels and their sensitivity to changes in humidity and temperature at different layers has been analyzed. It is shown that while some of the channels measure radiation emitted from the lower troposphere, none of the channels is sensitive to changes in the water vapor amount near the surface. This is due to the fact that the changes in the atmospheric and the earth contribution to the radiance, as a result of a change in the surface humidity, tend to cancel each other, in particular if the temperature gradient near the surface is small.

© 1983 Optical Society of America