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A simplified forward model of limb infrared emission spectra in a two-dimensional atmosphere

Coralie De Clercq(1) and Jean-Christopher Lambert(1)

(1) Belgian Institute for Space Aeronomy (IASB-BIRA), Avenue Circulaire 3, B-1180 Brussels, Belgium

Abstract

Most frequently, atmospheric constituent profiles are retrieved from satellite radiance measurements assuming a spherical atmosphere made of homogeneous, concentric layers. Averaging kernels associated with the retrieval enable one-dimensional characterisation of the retrieved information as a function of altitude or pressure. Nevertheless, two-dimensional characterisation of the information retrievable from satellite measurements is highly desirable for an increasing number of scientific and operational applications.

Here, we describe a simple radiative transfer model capable of calculating limb radiance emission spectra in a two-dimensional, inhomogeneous atmosphere. Radiative transfer basics resemble those adopted in the operational processing of Envisat Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) data. However, to keep it as fast and flexible as possible, the model assumes several simplifications having no or weak influence on geometrical aspects of the ray tracing. The model is applied to MIPAS particulars (limb scanning strategy, global fit retrieval approach, spectral microwindows) in order to investigate the distribution of information content along the optical path.

 

Keywords: ESA European Space Agency - Agence spatiale europeenne, observation de la terre, earth observation, satellite remote sensing, teledetection, geophysique, altimetrie, radar, chimique atmospherique, geophysics, altimetry, radar, atmospheric chemistry