Impact of Global Model Resolution on the Representation of Martian Wind-Stress Dust Lifting

Chapman, Rhian; Lewis, Stephen; Balme, Matthew and Steele, Liam (2017). Impact of Global Model Resolution on the Representation of Martian Wind-Stress Dust Lifting. In: 1st British Planetary Science Congress, 3-5 Dec 2017, Glasgow.

Abstract

The formation of large dust storms on Mars is believed to be driven by dust lifting due to near-surface wind stress (NSWS). Accurately representing this dust lifting within Mars Global Circulation Models (MGCMs) is important in order to gain a full understanding of the Martian dust storm cycle and climatology.
Model resolutions of ~ 5°x5° in latitude and longitude are often used in simulations of the Martian climate. This resolution represents large-scale weather patterns well, but small scale phenomena (e.g. near-surface winds) are not accurately depicted.
Parameterisations of dust lifting by NSWS exist within several MGCMs, but few studies have explored in detail how the results of these parameterisations are affected by changing the resolution of the model. We use the LMD-UK MGCM to complete simulations across multiple model resolutions. Our experiments range from ‘low’ resolution ~5° lat x ~5° lon to ‘high’ resolution ~1° lat x ~1° lon.
In experiments with fixed lifting parameters, we find that increasing the model’s horizontal resolution results in more dust being lifted; we also find that increasing the model’s number of vertical layers results in more dust being lifted. Geographical and temporal distributions of dust lifting are investigated, with the aim of developing a calibration scheme for this dust lifting across model resolutions. The scheme is verified through comparison with spacecraft observations of dust optical depths and dust storm locations.

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