Multiorder Etalon Sounder for vertical temperature profiling - Technique and performance analysis

In this paper a novel approach to high resolution infrared atmospheric temperature sounding by using the Multiorder Etalon Sounder (MOES) is discussed. The MOES exploits the periodic characteristics of Fabry-Perot Interferometer (FPI) transmission function and the uniform line spacings of carbon dioxide (CO2) to maximize the instrument signal and to achieve the high spectral resolution needed to improve the vertical resolution and retrieval accuracy of atmospheric temperature sounding. In this paper the MOES technique and a conceptual instrument design are presented. Suitable CO2 spectral regions, optimum etalon free spectral ranges, characteristics of 44 representative temperature sounding channels and 12 water vapor sounding channels are calculated and discussed. Performance simulation studies indicate that MOES can provide more accurate temperature and water vapor profiles than the current operational High Resolution Infrared Sounder (HIRS/2). The improvement in temperature and moisture retrieval accuracy with MOES is mainly due to its higher spectral resolution and the ability to resolve a single CO2 spectral line.