Effects of Local Dust Storms on the Upper Atmosphere of Mars: Observations and Simulations

Abstract

AbstractThe effects of a local dust storm on the upper atmosphere of Mars are researched through the observations of the lower and upper Martian atmosphere in the MGS (Mars Global Surveyor) radio occultation experiments. The ionosphere profiles in the high‐latitude region of northern hemisphere are thought to be under the influence of a local dust storm occurring in the low‐latitude areas during Ls 135–150°, Mars Year (MY) 27. A method to estimate the Martian upper neutral densities via the heights of ionospheric main peak is presented. Through the method, the 130‐km atmospheric neutral densities (or CO2 densities) of the area during the dust storm were calculated. MCD V4.3 (Mars Climate Database, Version 4.3) is used to derive the normal (or dust‐storm‐free) neutral densities of the same region and period. By analyzing the differences between the calculated densities and MCD (V4.3) simulated ones, the influence of the local dust storm on the upper atmosphere densities can be quantitatively derived. Based on the variation of the upper atmosphere densities, the behavior of regional ionospheric main peak under the dust storm can be simulated by a photochemical equilibrium model. The simulated ionosphere parameters are compared with the MGS‐observed ones, and it is found that two profile data sets are consistent with one another, thus indicating that the method employed to estimate the upper neutral densities is accurate.