Martian Cold Spot Regions and Associated Properties During a Global Dust Storm Year Using MRO Satellite Observations

Abstract

The weather and climate on Mars depend heavily on the characteristics of Martian aerosols. Dust, 𝐶𝑂2 ice, water ice, etc., suspended in the air, play a critical role in the thermal equilibrium, circulation, and transfer of momentum in Mars' atmosphere. Cold spot regions are those radiometrically cold areas where the temperature is less than 𝐶𝑂2 frost point temperature. These are the regions with the most probable chance of 𝐶𝑂2 ice formation. On Mars, global dust storms (GDS) drastically change the microphysical characteristics of 𝐶𝑂2 ice aerosols besides their geographical and vertical distributions. With the help of the Derived Data Record (DDR) version 5 obtained from the Mars Climate Sounder (MCS) instrument on board the NASA Mars Reconnaissance Orbiter (MRO) mission, we attempted to investigate the origin of cold spots, their spatial and temporal variation, etc.The work focuses on the cold spot regions' vertical, temporal, and spatial variation during the global dust storm (GDS) of Martian Year 34. It was found in the study that GDS affected the latitudinal variation in the formation of ice caps and lowered solar insolation, which in return impacted the cold spot formation. In the south pole, cold spot regions were more dominant than in the north pole, especially in non-polar ring regions. It was found that most North Pole cold spots formed on the polar nights, and during the global dust storm season, the cold spot regions in the northern hemisphere started to develop outside of polar ring regions. Also, during dust storms, there is a high concentration of dust at higher altitudes, which in return provides a nucleation site for 𝐶𝑂2 ice, leading to the formation of polar clouds.