Spectral Calibration of the Improved Stratospheric and Mesospheric Sounder

Abstract

The Improved Stratospheric and Mesospheric Sounder (ISAMS) is a limb-viewing infrared radiometer which measures thermal emission in 24 spectral bands, using both wideband (WB) and pressure modulator radiometer (PMR) techniques (Taylor, 1983). This enables the daily mapping over much of the Earth of temperature, the concentrations of 8 chemical species (water vapour, methane, ozone, nitric acid, nitrogen dioxide, nitric oxide, dinitrogen pentoxide, carbon monoxide) and aerosol opacity in the stratosphere and mesosphere. The instrument has eight separate focal planes, each consisting of a 4-element detector array, which are cooled by two mechanical coolers.