Modeling the distribution of subsurface seasonal water ice with varying atmospheric conditions at northern low to midlatitudes on Mars

It is of great significance to investigate the influence of seasonally varying atmospheric conditions on Martian seasonal subsurface water ice for understanding current Martian climate and performing subsequent detections for water. In this work, the regolith thermal model combined with the water vapor diffusion model was established to predict the presence of seasonal subsurface water ice. In particular, the radiation absorbed by the surface was considered under the seasonally varying atmospheric conditions. The influences of regolith properties and atmospheric properties on seasonal subsurface water ice were investigated in detail. Moreover, considering the local seasonally varying atmospheric conditions, we analyzed the distribution characteristics of seasonal subsurface water ice at northern low to midlatitudes, including the landing site of China's Tianwen-1. In low dust Martian years, our analysis shows that the near-surface water vapor partial pressure is the main atmospheric factor affecting the seasonal subsurface water ice distribution with respect to the dust optical depth and surface pressure. Larger near-surface water vapor partial pressures are more favorable for the accumulation of seasonal subsurface water ice. In addition, the subsurface water ice at lower latitudes is more sensitive to the seasonal variations in near-surface water vapor abundances, while for higher latitudes, the thermal factor, rather than the atmospheric factors, plays a dominate role for the subsurface water ice in this region. Large-scale and long-lasting global dust storms could be favorable for the massive accumulation of seasonal subsurface water ice by further reducing daytime surface temperature and even depositing CO2 ice on the surface, especially at higher latitudes. When considering the seasonal variations in near-surface water vapor abundances, the rapid growth of seasonal subsurface water ice in northern low to midlatitude regions is mainly attributed to the desorption of summertime adsorbed water.