Hemispheric difference in the momentum transport by waves encircling the summer polar region of Mars observed by MGS TES

Abstract

Hemispheric difference in the momentum transport by atmospheric waves in the Martian summer polar region was investigated by using the atmospheric temperature profiles taken by MGS TES. In the southern polar region, isolated zonal wave number‐1 temperature disturbances were prominent and upward EP (Eliassen‐Palm) fluxes were found indicating the existence of planetary waves, while they were obscure in the northern polar region. This north‐south difference is attributed to the difference in CO2 polar cap retreat: the asymmetric retreat of the southern polar cap which remains throughout the summer creates near‐surface temperature anomalies with the zonal wave number of unity and resultant planetary waves, while the nearly symmetric retreat of the northern polar cap do not create such disturbances. The momentum transport in the southern polar region will drive a localized meridional circulation with ascent at 70°S–80°S and descent over the pole. This meridional circulation would increase the atmospheric temperature by ∼10 K near the pole and transport dust that is lifted up by local dust storms.