DPS 34th Meeting, October 2002
Session 15. Mars
Poster, Chair(s): , Tuesday, October 8, 2002, 3:30-6:00pm, Exhibit Hall

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[15.16] Intercomparison of radiation codes for Mars Models: SW and LW

H.I. Savijarvi (Univ. of Helsinki), D. Crisp (JPL), A.-M. Harri (Finnish Meteor. Institute)

We have enlarged our radiation scheme intercomparison for Mars models into the SW region. A reference mean case is introduced by having a T(z) -profile based on Mariner 9 IRIS observations at 35 fixed- altitude points for a 95.3 per cent CO2-atmosphere plus optional trace gases and well-mixed dust at visible optical depths of 0, 0.3, 0.6, 1.0 and 5.0.

A Spectrum Resolving (line-by-line) multiple scattering multi-stream Model (SRM, by Crisp) is used as the first-principles reference calculation. The University of Helsinki (UH) old and new (improved) Mars model schemes are also included. The intercomparisons have pointed out the importance of dust and water vapour in the LW, while the CO2 spectral line data difference effects were minimal but nonzero.

In the shortwave, the results show that the CO2 absorption of solar radiation by the line-by-line scheme is relatively intense, especially so at low solar height angles. This is attributed to the (often neglected) very weak lines and bands in the near-infrared. The other trace gases are not important but dust, of course, scatters and absorbs strongly in the shortwave. The old, very simple, UH SW scheme was surprisingly good at low dust concentrations, compared to SRM. It was however considerably improved for both low and high dust amounts by using the SRM results as benchmark.

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Bulletin of the American Astronomical Society, 34, #3< br> © 2002. The American Astronomical Soceity.