Effect of dust particle size on the climate of Mars

Dust particle size is one important property in evaluating the radiative effect of airborne dust. However, its effect on the climate of Mars is not clearly understood. In the present study, some numerical experiments with the Mars climate model MarsWRF have been performed to investigate this issue. In these simulations, the ratio of two sizes (small and large) of dust particles is changed gradually to investigate the corresponding effects on the distribution of dust mixing ratio, thermal field, and the dynamic field. Based on the results of this study, the following effects on the Martian climate have been identified. (1) The effect of small dust particles is significant in the dust season and mainly in the lower atmosphere. (2) Increasing the ratio of small dust particles may increase the heating rate, temperature, westerly wind, and the meridional wind associated with the Hadley circulation during the dust season, as well as a decrease in the easterly wind over the equatorial region. (3) The effect of increasing the ratio of small dust particles is generally more significant in the second episodic dust period during the dust season. This may be due to the longer time of sedimentation for small dust particles.