[Baps] Scot Rafkin to be Monday's MASS speaker

[Angela Marie Zalucha]

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=============  M.I.T. Atmospheric Seminar Series ===============
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               Monday, October 26 at noon in 54-915
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                             Scot Rafkin
                     Southwest Research Institute
     "Positive Radiative-Dynamic Feedback Between Atmospheric
          Dust Disturbances and the Surface of Mars"
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====== http://paoc.mit.edu/paoc/events/seminars/mass.htm =======
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Abstract:
Atmospheric dust, through its interaction with incoming solar and outgoing 
infrared energy, plays an important role in regulating the climate of Mars 
and in forcing atmospheric dynamics.  Since the lifting of dust from the 
surface is fundamentally a result of atmospheric circulations, there is 
the potential for feedback between atmospheric dynamics, dust lifting 
processes, and the radiative perturbations that ensue.  Previous studies 
have investigated the effect of atmospheric dust on the mean meridional 
circulation (Hadley Cell) and the growth rate of dynamic instabilities 
that might result from vertical gradients of dust concentration.  Other 
studies have investigated the origin of dust disturbances resulting from 
atmospheric circulations, but without consideration of how the lifted dust 
may influence the parent atmospheric circulation.  In this talk, I will 
present results of numerical studies designed to explicitly test and 
quantify the feedback between atmospheric dust disturbances and the dust 
lifted from the surface.  It is shown that in all but trivial cases, there 
is a positive feedback between atmospheric circulations and lifted dust. 
The feedback magnitude, however, is highly dependent upon the dust lifting 
physics, the atmospheric thermodynamic structure, solar flux, and 
latitude.  Furthermore, the importance of developing a quasi-balanced 
(e.g., vortical) circulation to the growth and maintenance of disturbances 
is demonstrated.  Finally, the close analogy between the dust feedback 
process of Mars and the Wind-Induced Sensible Heat Exchange (WISHE) 
hypothesis for terrestrial hurricane intensification is discussed.



Upcoming seminars:

Nov. 2 - Erwan Monier (MIT): "Climatology and Trends in the Wave Forcing of the 
Stratospheric Zonal-Mean Flow and Ozone Transport in the ERA-40"

Nov. 5 @ 4 pm - Gill-Ran Jeong (MIT): TBA

Nov. 9 - Tim Eichler (St. Louis University): TBA