Publication Date:
2011-08-16
Description:
The secular variation of the thermal structure of the Martian atmosphere during the dissipation phase of the 1971 dust storm is examined, using temperatures obtained by the infrared spectroscopy investigation on Mariner 9. For the latitude range -20 to -30 deg, the mean temperature at the 2-mbar level is found to decrease from approximately 220 K in mid-December 1971 to about 190 K by June 1972 while for the 0.3-mbar level a decrease from 203 K to 160 K is observed. Over the same period, the amplitude of the diurnal temperature wave also decreased. Assuming a simplified radiative heating model, the dust optical depth is found to decrease approximately exponentially with an e-folding time of about 60 days at both the 0.3- and 2-mbar levels. Stokes-Cunningham settling alone cannot account for this behavior. Sedimentation models which include both gravitational settling and vertical mixing are developed in an effort to explain the time evolution of the dust.
Keywords:
LUNAR AND PLANETARY EXPLORATION
Type:
Icarus; 24; Jan. 197
Format:
text
