LIMB RADIANCE MODELING INTERCOMPARISON FOR NON-LOCAL THERMODYNAMIC EQUILIBRIUM CONDITIONS

THOMAS VON CLARMANN and N.N.

Forschungszentrum Karlsruhe, Institut für Meteorologie und Klimaforschung (IMK),

P.O. Box. 3640, D-76021 Karlsruhe, Germany

The Remote Sensing of the Middle Atmosphere (RSMA) working group of the International Radiation Commission (IRC) has launched activities in the research area of intercomparison of non-local thermodynamic equilibrium (non-LTE) population models and radiative transfer codes. Part of these activities is calculation and intercomparison of the nonequilibrium limb radiance on the basis of given reference models of the atmosphere which include precalculated nonequilibrium populations. Furthermore, in order to better explain potential discrepancies, also difference spectra between non-LTE and respective LTE spectra will be intercompared. Spectral regions of special interest are the CO2 15 µm band, and the region of the ozone 9.6 µm band and the CO2 10 µm laser band. Calculations are carried out for tangent altitudes between 40 and 120 km. Both high resolution models and medium resolution models are considered. The main goals of the study are intercomparison of the results and analysis of the reasons of discrepancies, correction of algorithms and their unification, and formulation of the most important problems and requirements for the purpose of increasing accuracy. We shall present intermediate results available by the time of the meeting.