Requirements for an Operational Interferometer Thermal Sounder

Abstract

This paper summarizes the work of a group of consultant experts in the area of sounding retrieval and interferometer retrieval methodology convened to provide EUMETSAT with advice on the interferometer sounder issues. The EUMETSAT Sounder Science Working Group (ESSWG), whose members are listed at the end of this paper, has reviewed the meteorological requirements for an interferometer for sounding the atmosphere in the infrared region, to be developed for operational implementation on the EUMETSAT Polar System (EPS) intended as the a.m. satellite of the world’s two polar orbiting meteorological satellite system. The Working Group has produced a report by the title “Requirements for an Operational Interferometer Thermal Sounder”, November 1991, in which specifications are provided to satisfy the operational high vertical resolution temperature and moisture sounding mission. The assumption for the Working Group was that the operational interferometer sounder should be designed to incorporate low risk and proven technology with the minimum complexity needed to accomplish the mission throughout the operational lifetime of the spacecraft. For the first EPS application the instrument’s spectral resolution and spectral coverage are limited to that needed to provide high vertical resolution temperature and moisture sounding. However, the interferometer sounder specifications also allow for the measurement of other parameters important for climate, such as surface properties, cloud distribution and properties, water vapour distribution and greenhouse gases concentrations. In parallel to this activity EUMETSAT has sponsored an industrial study for an Interferometer Thermal Sounder (ITS) performed by the Santa Barbara Research Center and the University of Wisconsin, in order to investigate the feasibility of the approach and gain independent engineering assessment.