Martian atmosphere during the 2001 global dust storm: Observations with swas and simulations with a general circulation model

The Earth-orbiting submillimeter wave astronomy satellite (SWAS) observed the global mean surface and atmosphere temperature on Mars as a function of the altitude. Unlike for the infrared spectrometers, the temperature retrievals from submillimeter instruments can be performed in the presence of the atmospheric dust. During the 2001 global dust storm on Mars, SWAS measured the atmosphere and surface temperature for aerocentric longitudes from L_s = 166° to 233°, and observed the temperature inversion in the lower atmosphere. We use a recently developed general circulation model of the Martian atmosphere to simulate the temperature and other atmospheric fields under the conditions corresponding to those during the SWAS measurements. The model takes into account the radiative effects of the atmospheric dust. Simulations show an overall agreement with the SWAS measurements. In particular, the model reproduces the inversion of the global mean temperature and the surface cooling detected by SWAS. Time series of the globally averaged surface and atmospheric temperature at 0.05 hPa (~49km) are also in a good agreement with the measurements. Without the dust, the model cannot reproduce these features. A brief discussion of the differences between the model and observations as well as their possible reasons is provided.