Searching for springtime zonal liquid interfacial water on Mars

Abstract

We analyzed the spatial and temporal characteristics of the surface temperature at the northern water ice annulus on Mars that is left behind the receding seasonal carbon dioxide cap in springtime. Using OMEGA hyperspectral images we show that water ice without carbon dioxide ice coverage lasts for 10–30days between 55° and 70°N. The longest water ice coverage without CO2 ice is observed between 40–55°N and 300–330°E and lasts 80–110days in ideal case. Using TES temperature data, we show that thin interfacial liquid water may be present at the water ice annulus. Higher spatial resolution THEMIS temperature data shows that the above mentioned finding is relevant to a spatial scale of 100m. Although the exact near surface water vapor concentration is not known, beside the average 10pr-μm we used two elevated values and corresponding threshold temperatures for interfacial liquid water formation: 190 and 199K beside the average 180K. While the area of interfacial liquid water is substantially smaller in the case of higher threshold temperature values, even for 199K terrains exist at THEMIS and OMEGA scale of resolution where such thin interfacial liquid water could be present on the surface. Summarizing: good chance exists for the presence of liquid interfacial water in the warmest part of the day on at the northern hemisphere of Mars at extended areas – although firm evidence requires better targeted future observations.