An effective method for the detection of trace species demonstrated using the MetOp Infrared Atmospheric Sounding Interferometer

摘要

Fast and reliable methods for the detection of atmospheric trace species areneeded for near-real-time applications including volcanic hazard avoidance.One common approach using hyperspectral instruments is to measure the differencein brightness temperature between a small number of target sensitive andbackground channels to determine the presence of the target species. Althoughfast and robust, current brightness temperature difference methods do not fullyexploit the spectral range and resolution of hyperspectral instruments, and thenoise associated with the measurements remains high. In this paper, we describea way to make full use of the spectral information from hyperspectral soundersallowing the presence of the target species to be determined with much bettersensitivity in near-real-time if required. The technique is demonstrated usingthe MetOp Infrared Atmospheric Sounding Interferometerconsidering two case studies: (a) the detection of sulphur dioxide from theeruption of the Kasatochi volcano in Alaska in August 2008, and (b) thedetection of ammonia emissions related to agriculture over Southern Asia inMay 2008. The performance of this method iscompared against that of existing brightness temperaturedifference methods. It is found that the sensitivity of the detectionof these trace species is improved by up to an order of magnitude.