Inversion technique for IR heterodyne sounding of stratospheric constituents from space platforms

Abstract

The techniques which have been employed for inversion of IR heterodyne measurements for remote sounding of stratospheric trace constituents usually rely on either geometric effects based on limb-scan observations (i.e., onion peel techniques) or spectral effects by using weighting functions corresponding to different frequencies of an IR spectral line. An experimental approach and inversion technique are discussed which optimize the retrieval of concentration profiles by combining the geometric and the spectral effects in an IR heterodyne receiver. The results of inversions of some synthetic ClO spectral lines corresponding to solar occultation limb scans of the stratosphere are presented, indicating considerable improvement in the accuracy of the retrieved profiles. The effects of noise on the accuracy of retrievals are discussed for realistic situations.

Far infrared remote sounding of stratospheric temperature and trace gas distributions

“…The synthetic spectral data for limb-tangent paths were calculated for a model atmosphere (with O~, 03, and HzO gas profiles included) by using a line-by-line transmittance model (Kunde and Maguire, 1974;Abbas et al, 1979Abbas et al, , 1981 which includes curvature and refraction effects. The frequency-dependent quantities are averaged over the instrument function (assumed Hamming function with the full width = 0.003 cm -1 Error AT(K) Fig.…”

“…The temperature retrieval is started at the top tangent height and proceeds successively to the lower tangent height (e.g., Abbas, 1981). A set of frequencies near some isolated 02 lines is chosen such that the weighting functions are sharply peaked near the tangent heights.…”

“…Spectral inversion techniques for the retrieval of thermal structure and trace constituent distributions from thermal emission spectra have become well developed during the last 15 years or so (e.g., Chahine, 1980Chahine, , 1972Smith, 1970;Gille and House, 1971;Conrath, 1977;Deepak, 1977;Abbas et al, 1979Abbas et al, , 1980Abbas et al, , 1981. Both temperature and gas concentration profiles may be obtained with high vertical-spatial resolution from an inversion of the thermal emission spectrum of the Earth's limb.…”

Finite field of view effects on inversion of limb thermal emission observations

“…Thermal emission limb tangent observations have an additional advantage not possessed by solar transmission measurements; observations can be made for any desired angle and for any desired path during the diurnal cycle. The vertical temperature and constituent profiles are retrieved from the observed spectrum by employing analytical inversion methods which have been developed extensively in recent years [Chahine, 1970[Chahine, , 1972Smith, 1970;Gille and House, 1971;Conrath, 1977;Abbas et al, 1979Abbas et al, , 1981 In this paper we examine the FOV effects on the inversion of infrared thermal emission measurements for balloon platforms. In particular, analytical and numerical techniques are discussed for calculation of the weighting functions and for retrieval of temperature and constituent distributions from thermal emission observations with a finite FOV.…”

Far‐infrared measurement of stratospheric carbon monoxide

“…From some 15 available CO lines in the 23-73 cm-• region, only a few were found to be isolated. The two relatively weak CO features at 34.588 cmq and 49.932 cm-• were found to be of sufficient strength in the observed high resolution spectra for retrieval of the stratospheric vertical profile.AnalysisThe analytical techniques employed for retrieval of trace õas distributions from balloon-based high resolution infrared thermal emission spectra have been discussed in previous publications[Abbas et al, 1981[Abbas et al, , 1984[Abbas et al, , 1985[Abbas et al, , 1987a. A brief review, relevant to the CO distribution presented in this paper, is given here.…”