Physics
Scientific paper
Dec 2009
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2009agufmep21a0579w&link_type=abstract
American Geophysical Union, Fall Meeting 2009, abstract #EP21A-0579
Physics
[0343] Atmospheric Composition And Structure / Planetary Atmospheres, [3314] Atmospheric Processes / Convective Processes, [3322] Atmospheric Processes / Land/Atmosphere Interactions, [5405] Planetary Sciences: Solid Surface Planets / Atmospheres
Scientific paper
Dust devils dominate the volcanic plains at the Mars Exploration Rover (MER) landing site within the Low Albedo Zone (LAZ) in Gusev Crater. Previous studies indicate that the inferred pressure drop within the dust devil core allows the vortex to lift large amounts of unconsolidated dust high into the atmosphere which contributes to the atmospheric haze. Previous laboratory results indicate that dust devils are efficient in lifting very fine-grained (<10 μm) material, even when boundary layer winds do not exceed previously predicted threshold wind speeds (~30-35 m/s at 1.5 m above the surface for Mars conditions). Since landing in Gusev crater in January 2004, MER Spirit has obtained data for two dust devil seasons (defined as the period of time when the first and last dust devils were imaged), with a third season currently being analyzed. These seasons typically correspond to southern spring and summer, when winds capable of lifting sediment are determined to be most frequent. All observations for Season One were taken as Spirit neared the summit of Husband Hill. During Season Two Spirit imaged dust devils in the plains as it traversed within the Inner Basin, a low-lying area in the Columbia Hills complex. All results were extrapolated so that they are representative of the entire LAZ. Season One lasted 270 sols (March 2005 to December 2005 corresponding to Ls 173.2 to 339.5 degrees), whereas Season Two lasted 153 sols (January 2007 to June 2007 corresponding to Ls 171.2 to 266.7 degrees) and ended suddenly on sol 1240 just after the dust devil frequency peaked for the season. This abrupt drop in dust devil activity corresponded to atmospheric opacity levels that exceeded 1.0 and the onset of a global dust storm that originated in the southern hemisphere that engulfed Gusev within weeks. Results show a large contrast in activity between the two seasons. An 81% decrease in dust devil frequency across the plains was found in Season Two. 533 dust devils were imaged during Season One and resulted in an average of ~50 active dust devils/km2/sol extrapolated out to the LAZ while 103 dust devils were imaged during Season Two resulting in an average of ~5 active dust devils/km2/sol within the LAZ. This drop in dust devil frequency from one season to the next was coupled with a 50% decrease in the amount of dust loaded into the atmosphere during Season Two (~19 kg/km2/sol in Season One and ~10 kg/km2/sol in Season Two). Previous models indicate that the increased amount of dust in the atmosphere during the storm decreased the amount of solar insolation to the surface therefore also decreasing the surface heat flux. The rapidly decreasing surficial heat flux prevents the temperature lapse rate (change in temperature gradient with elevation) from becoming super-adiabatic and therefore causes the low-altitude atmospheric temperature profile to become too homogeneous to sustain convective plumes.
Greeley Ronald
Landis Geoffrey A.
Neakrase L. D.
Thompson Shane D.
Waller Devin A.
No associations
LandOfFree
Dust loading in Gusev crater, Mars: Results from two active dust devil seasons does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Dust loading in Gusev crater, Mars: Results from two active dust devil seasons, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Dust loading in Gusev crater, Mars: Results from two active dust devil seasons will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1776623