Dust Lifting and Deposition Over Six Mars Years at Gale Crater, Mars, From REMS Observations and Mesoscale Simulations

We present the temporal evolution of the effect of dust accumulation on two surfaces of the Curiosity rover at Gale crater during almost 4,000 sols using Rover Environmental Monitoring Station (REMS), Chemcam and Mastcam observations, and compare it with simulations of the Mars Weather Research and Forecasting Model (MarsWRF) atmospheric numerical model and environmental observations to improve our understanding of dust lifting on Mars. After almost six full Mars Years (MY), dust accumulated on the REMS UV sensor (UVS) attenuates an average of 45% of the incoming radiation. Dust accumulation on the UVS follows a seasonal cycle with gradual dust accumulation during the aphelion season followed by dust removal until L_s ∼ 300°. However, there is a strong interannual variability during the dusty season. MarsWRF simulations show that wind stress has a strong diurnal, seasonal and interannual variability; simulations of dust devil activity show a seasonal pattern that aligns with pressure drop observations, peaking also at L_s ∼ 300°. Dust lifting mechanisms are variable, with a larger relative importance of wind stress in MY 31 and 32, and of dust devils in MY 34 to 36. Dust accumulation on the Chemcam calibration target follows a very similar temporal evolution, but with a marked offset since the 2018 Global Dust Storm, suggesting that surface tilt is particularly important around intense dust storms. We characterize dust lifting mechanisms at Gale crater and quantify the effect of dust accumulation during an extraordinary dust storm on different surfaces; the observed net removal periods validate MarsWRF simulations and suggest the suitability of Gale Crater for long-term solar-powered missions.