The Periglacial Landforms and Estimated Subsurface Ice Distribution in the Northern Mid‐Latitude of Mars

Abstract Subsurface ice in the mid‐latitude regions is a significant water inventory on present‐day Mars, and their volume and distribution are thought to have varied due to the orbitally induced paleoclimatic changes. Using high‐resolution satellite images, the present study explores the distributions of three presumed periglacial landforms (thermal contraction polygons, fractured mounds, and brain terrains) that could provide evidence for the present‐day subsurface ice distribution in the northern mid‐latitude (30°–42°N). We identified the three periglacial landforms concentrated within the regions of 0°–40°E, 60°–100°E, and 160°–210°E in the latitude of >33°N. Their distributions are in agreement with the occurrence of fresh ice‐exposing craters and the estimated area of high annual water ice budget obtained by the general circulation model, reflecting the present‐day subsurface ice distribution. We further classified the thermal contraction polygons into five types based on their morphology, and investigated various distribution patterns for each type. Among them, high‐centered polygons are the most abundant type in the survey area, whereas low‐centered polygons are less prominent and observed only at >38°N. The large‐sized mixture polygons, which were only found in certain areas of 57°–92°E, are distributed in areas where the atmospheric model indicates that the highest annual water ice budget occurred during the past high‐obliquity period, but that the water ice budget has decreased during the present‐day low‐obliquity condition. These findings, along with insights from possible terrestrial analogs in the Arctic Archipelago and northern Canada, suggest that regions where large‐sized mixture polygons formed contained significant amounts of water ice in the past, but have undergone intense degradation over time.