Pressure Deficit in Gale Crater and a Larger Northern Polar Cap After the MY34 Global Dust Storm

We describe the model-independent analysis technique of Mars Science Laboratory (MSL) pressure and Mars Climate Sounder (MCS) data in de la Torre Juarez et al. (2019, ) that compared multiple years of surface pressures on Gale before, during, and after the Global Dust Storm of Mars Year 34. The analysis found (a) representative pressure scale heights over Gale; (b) that the storm was followed by a pressure deficit at Gale; (c) the following C storms did not eliminate the deficit; (d) changes in the duration of the polar caps condensation seasons, with an early start of the North Polar (NP) ice cap growing season the year before the Great Dust Storm (GDS) and a late signature of the end of the expansion season thereafter, changes consistent with a larger growth phase of the NP cap; (e) MCS observed a larger than usual NP cap; and (f) cold temperature anomalies over the NP and warm over the Southern Pole after the storm. We also show that the analysis of observed MSL pressure data alone filters out effects on the pressure signal that are attributable to dynamical and orographic processes in a recent model analysis that makes similar interpretations as our 2019 study. One additional Mars year of observations is included to eliminate early concerns about sensor drifts. Noting that a similar NP anomaly was observed with MCS data after the last early GDS in MY25, and not the later GDS of MY27, the results suggest a possible unique effect of early GDSs. In 2018, Mars Year 34, Mars experienced a dust storm that encircled the whole planet and darkened its skies more than most storms in the recent past. Already in 2019 an analysis reported surface pressures below the climatological values observed over the previous 3 years in Gale Crater. The pressure deficit persisted into Mars Year 35 long after the end of the storm and dust over Gale had returned to levels from previous years. The storm coincided with a longer duration of the condensation season of the North Polar ice cap and a subsequent increase in its maximum amount of ice volume. We perform here a full analysis of five Mars Years of data showing how the duration of the polar caps sublimation/condensation seasons changed around the time of the storm, that the extension of the polar caps changed, and that the atmosphere above the North Pole was slightly colder than in years before the storm. A technique to measure representative pressure scale heights at Gale enables tracking signatures of changes in the polar ice capsREMS surface pressure with Mars Climate Sounder observations are used to describe the polar processes after the great storm of Mars Year 34Multiannual pressure data show a short Southern Polar Cap growth season before the storm followed by a long Northern Polar Cap growth season