Satellite-borne measurements of middle-atmosphere temperature

Abstract

Satellites were first used to measure middle-atmosphere temperatures in the early 1960s. There has been steady progress towards the present position-where we have routine observations of the whole stratosphere with 10—15 km vertical resolution by operational satellites, and where experimental instruments provide data as high as the mesopause, with 3 km vertical resolution in some cases. Vertical-viewing geometry is used in the simplest instruments, but limb viewing gives some advantages and has been exploited during the last decade. Measurements of the temperature field as a function of pressure allow the determination of geopotential height, hence of motions. The most complete geographical and temporal coverage is obtained by instruments that sense thermal emission, either in the infrared or the microwave. However, measurements of atmospheric infrared absorption from solar occultation, and of pressure scale height from measurements of solar scattering by air molecules, are also used to determine temperature. The paper outlines the present state of the art and will attempt to show how well we can hope to do in the future.