A future atmospheric chemistry sensor: the Limb Infrared Fourier Transform spectrometer

Abstract

Natural and anthropogenic trace constituents play an important role for the ozone budget and climate as well as in other problems of the environment. Atmospheric trace aerosol distribution plays an important role in key evolutions of the Earth atmosphere, such as stratospheric ozone depletion and greenhouse effects. In order to monitor those changes and to try to prevent their dramatic impact, exchange processes between the stratosphere and troposphere as well as the distribution and deposition of tropospheric trace constituents are investigated. The mission and the design of the Limb Infrared Fourier Transform spectrometer (LIFT) instrument are described. This instrument supply observation of species with regard to eight specific questions centred on climate-chemistry interactions and the role of anthropogenic emissions. LIFT will globally provide calibrated spectra of the atmosphere as a function of the tangent altitude. The users will subsequently retrieve altitude profiles of the target species from the spectra. LIFT field of view will be 30 km in elevation and in azimuth. The resolution of this instrument is 30 km in azimuth corresponding to the full field of view, while it is only 2 km in elevation, obtained by using a matrix of 15×15 detectors. The instrument will cover the spectral domain 5.7-14.7 μm through 2 different bands respectively 13.0-9.5 μm, 9.5-5.7 μm. With a spectral resolution of 0.1 cm-1, LIFT is a high class Fourier Transform Spectrometer compliant with the challenging constraints of limb viewing and spaceborne implementation.