Diurnal and Seasonal Mapping of Martian Ices With EMIRS.

Condensation and sublimation of ices at the surface of the planet is a key part of both the Martian H2O and CO2 cycles, either from a seasonal or diurnal aspect. While most of the ice is located within the polar caps, surface frost is known to be formed during nighttime down to equatorial latitudes. Here, we use data from the Emirates Mars Infrared Spectrometer onboard the Emirates Mars Mission to monitor the diurnal and seasonal evolution of the ices at the surface of Mars over almost one Martian year. The unique local time coverage provided by the instrument allows us to observe the apparition of equatorial CO2 frost in the second half of the Martian night around the equinoxes, to its sublimation at sunrise. Plain Language Summary: The H2O and CO2 ices that form at the surface on Mars play an important role in the exchange between the atmosphere and the surface of the planet. While most of the ice is located within the two polar caps that grew and shrink seasonally, ice is also known to condensate as surface frost during the night and sublimate during the day. This nighttime surface frost deposition can be observed even at equatorial latitudes. In this paper we use data from the Emirates Mars Infrared Spectrometer onboard the Emirates Mars Mission to detect the H2O and CO2 ices at the surface of the planet at all local times over almost one Martian Year, which allows us to monitor both the seasonal and diurnal evolution of the distribution of ices at the surface of Mars. We observe that nighttime CO2 frost forms at equatorial latitudes in the second half of the night to disappear at sunrise around the Martian equinoxes. Key Points: We monitor the seasonal growth and retreat of both polar caps over MY 36We monitor the presence of CO2 ice on the surface of Mars over MY 36, through the season and through all times of dayCO2 ice appears at the surface at equatorial latitudes during the second half of the night around the equinoxes [ABSTRACT FROM AUTHOR]