Séminaire
Atmospheric dust plays an important role in regulating the climate of Mars and it also strongly influences the deposition of incoming solar energy and outgoing infrared radiation,thereby influencing atmospheric dynamics.
Therefore, the atmospheric dust cycle is intrinsically a key element to understanding the weather and climate system of Mars, including stochastic dust storms. 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 general circulation 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.