Modeling the Bregional dust storm on Mars: Dust lofting mechanisms predicted by the new NASA Ames Mars GCM

During years in which Mars does not experience a Global Dust Storm, the Thermal Emission Spectrometer (TES) instrument on Mars Global Surveyor (MGS) and the Mars Climate Sounder (MCS) instrument on Mars Reconnaissance Orbiter (MRO) have observed three annually-recurring regional-scale dust storms that occur in the southern hemisphere during southern spring and summer. These storms produce dust extinctions in excess of 10-3 km-1 and increase temperatures to over 200 K in the middle atmosphere (50 Pa, or similar to 25 km). Whereas the first and last storms in the occurrence are located in the middle latitudes, the second storm, known as the Bstorm, is confined to the south pole over the receding CO2 ice cap. In this work, we reproduce the Bstorm in the new NASA Ames Mars Global Climate Model (MGCM), and we use our simulation to investigate the mechanisms lofting dust into the middle atmosphere during the storm. We find that a series of semi-regular dust pluming events that occur poleward of 70 degrees S loft dust to and above 50 Pa during the Bstorm. These plumes share some characteristics with rocket dust storms and often produce detached dust layers whose subsequent evolution resembles the solar escalator effect.

Automated summary

Regional dust storms occur in the southern hemisphere of Mars during spring and summer, with one storm specifically confined to the south pole. The NASA Ames Mars Global Climate Model (MGCM) is used to recreate this storm and investigate the mechanisms responsible for the uplift of dust into the middle atmosphere. The study finds that semi-regular dust pluming events poleward of 70 degrees S contribute to the dust load in the middle atmosphere during the storm.