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M. D. Smith (NASA GSFC), B. J. Conrath (Cornell), J. C. Pearl (NASA GSFC), P. R. Christensen (Arizona St.)
The initiation and evolution of a planet-encircling dust storm on Mars have been observed in unprecedented detail by the Thermal Emission Spectrometer (TES) on-board the Mars Global Surveyor. TES infrared spectra are very well suited for the quantitative monitoring of atmospheric temperatures and aerosol (dust) loading. A local dust storm began to quickly expand on June 26, 2001 (Ls=185), becoming a planet-encircling dust storm by July 11, 2001 (Ls=193). This is the earliest seasonal date ever observed for a planet-encircling dust storm. The dust storm had 9-micron dust optical depth of 2 over wide areas and caused atmospheric temperatures over a large vertical range to warm by >40 K from 20 N latitude to the south pole. The amplitude of the Hadley circulation and thermal tides were enhanced. Dust optical depth and atmospheric temperatures reached their maximum values around August 1, 2001 (Ls=206). The subsequent clearing of the dust storm was more rapid at high southerly latitudes than near the equator.