A diagnostic model to estimate winds and smallscale drag from Mars Observer PMIRR data
Abstract
Theoretical and modeling studies indicate that smallscale drag due to breaking gravity waves is likely to be of considerable importance for the circulation in the middle atmospheric region (approximately 40100 km altitude) on Mars. Recent earthbased spectroscopic observations have provided evidence for the existence of circulation features, in particular, a warm winter polar region, associated with gravity wave drag. Since the Mars Observer PMIRR experiment will obtain temperature profiles extending from the surface up to about 80 km altitude, it will be extensively sampling middle atmospheric regions in which gravity wave drag may play a dominant role. Estimating the drag then becomes crucial to the estimation of the atmospheric winds from the PMIRRobserved temperatures. An interative diagnostic model based upon one previously developed and tested with earth satellite temperature data will be applied to the PMIRR measurements to produce estimates of the smallscale zonal drag and threedimensional wind fields in the Mars middle atmosphere. This model is based on the primitive equations, and can allow for time dependence (the time tendencies used may be based upon those computed in a Fast Fourier Mapping procedure). The smallscale zonal drag is estimated as the residual in the zonal momentum equation; the horizontal winds having first been estimated from the meridional momentum equation and the continuity equation. The scheme estimates the vertical motions from the thermodynamic equation, and thus needs estimates of the diabatic heating based upon the observed temperatures. The latter will be generated using a radiative model. It is hoped that the diagnostic scheme will be able to produce good estimates of the zonal gravity wave drag in the Mars middle atmosphere, estimates that can then be used in other diagnostic or assimilation efforts, as well as more theoretical studies.
 Publication:

Atmospheric Transport on Mars
 Pub Date:
 1993
 Bibcode:
 1993atm..workQ...6B
 Keywords:

 Atmospheric Circulation;
 Drag;
 Gravity Waves;
 Mars Atmosphere;
 Planetary Meteorology;
 Primitive Equations;
 Velocity Distribution;
 Wind (Meteorology);
 Atmospheric Temperature;
 Mars Observer;
 Satellite Sounding;
 Temperature Profiles;
 Time Dependence;
 Wind Velocity;
 Lunar and Planetary Exploration