Detection of Polar Stratospheric Clouds with Next Generation IR Sounders

Abstract

A bispectral approach to temperature determination of semitransparent clouds is taken to identify areas covered by Polar Stratospheric Clouds (PSCs). The method uses information from two satellite pixels and two spectral channels in the infrared. PSCs form and emit in very cold stratospheric environments (<195 K), and solutions of the bispectral method yield low temperatures in a range that clearly differ from those derived for a cold but cloudfree stratosphere. Application of the method to HIRS data of the NOAA-satellite gained during the major PSC event on January 31 1989 identified large areas covered by dense PSCs which were in very good agreement with independent airborne measurements. Simulations demonstrate the potental of the method with high spectral resolution IR sounder information.