RELEASE DATE: For release on Jan-07-03 (for Joy Crisp's presentation
at the 9am press conference).

IMAGE FILE NAME: TES_DustOpticalDepth.tiff 


NAME OF SUBMITTER: Michael D. Smith, NASA Goddard


TITLE OF IMAGE: Dust optical depth at the Mars Exploration Rover landing sites 
(Dec. 2003 to early January 2004.

CAPTION:

This plot shows the observed change in dust optical depth, at visible 
wavelengths, in December 2003 and early January 2004 at Gusev Crater 
(red curve) and Meridiani Crater (black curve).  These estimates were retrieved 
from Mars Global Surveyor Thermal Emission Spectrometer (TES) data by 
Michael D. Smith, NASA Goddard.  The assumption was made that the dust 
optical depth at visible wavelengths is a factor of two larger than 
at the TES wavelength of measurement, 9 micrometers.  A large regional 
dust storm began in mid-December that raised significant dust near Meridiani.  
Smaller amounts of dust were spread globally by winds, the effects of 
which were seen at Gusev Crater.