Using the NASA Ames GCM to evaluate the importance of dust devils on the evolution of surface dust r

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Using the NASA Ames GCM to evaluate the
importance of dust devils on the evolution of
surface dust reservoirs on Mars

• M.A. Kahre, J.R. Murphy, R.M. Haberle, P.R.
  Christensen, R. Greeley

Dust Devil Activity -Rennó et al. (1998)
-Newman et al. (2002)
GOAL To understand the role of dust devils in
the martian dust cycle and the depth evolution of
the surface dust reservoirs in Arabia, Tharsis,
and Elysium. METHOD Incorporate radiatively
active dust lifting, transport, and deposition
into the Ames GCM. Two Dust Lifting
Mechanisms Wind Stress Dust Devil Lifting

• FD lifted dust flux
• D efficiency factor
• Fs sensible heat flux
• Pcon pressure at top of PBL
• Ps surface pressure

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Simulated dust devil lifting compares well to
observations
Simulated dust devil lifting rate peaks between
12 pm and 2 pm at the gridpoint nearest MPF ?
Consistent w/ observations (Murphy and
Nelli 2002) Maximum simulated dust devil activity
occurs in Amazonis ? Consistent with dust
devil survey (Fisher et al.
2005) Peak annual dust devil lifting rate occurs
during local summer ? Consistent with dust
devil surveys (Fisher et al. 2005)
Histogram Observations Solid Curve Model
Results
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Dust Devils and the Martian Dust Cycle
Dust devils maintain the background dust haze
during northern spring and summer Dust devils
contribute 1/2 of the total dust lifted
annually
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Low Thermal Inertia Continents
According to our model, Tharsis, Arabia, and
Elysium are not currently accumulating
dust Simulated dust devil lifting is responsible
for this lack of dust accumulation