On the location of a priori information to the solution of inverse problems of remote sensing of the non-LTE atmosphere in the infrared region by high-resolution spectral instruments

Abstract

The optimal estimation method has been applied to the solution of the inverse problem of the retrieval of atmospheric composition, vibrational temperature profiles of gases under non-LTE (non-local thermodynamic equilibrium) conditions, and kinetic temperature profile from the limb measurements of atmospheric radiance and transmittance in the infrared region. The efficiency of the multi-parameter retrieval algorithm has been investigated in a number of numerical experiments simulating the MIPAS and ATMOS measurements. The influence of 4 types of a priori information on the retrieval accuracy is discussed: (1) “initial guess”; (2) a priori uncertainties and covarlances of unknown variables; (3) the knowledge of the altitude level of the breakdown of LTE for different vibrational transitions; (4) coupling of levels with close energies in accordance with LTE.