Seasonal Variation in Martian Water Ice Cloud Particle Size

Abstract

AbstractWe employ the complete record of Mars limb‐viewing observations by the Compact Reconnaissance Imaging Spectrometer for Mars, totaling 922 successful retrievals, to chart the seasonal variation in water ice cloud particle size. Low‐latitude clouds exhibit particle size sorting with altitude at all seasons, with particles ranging from >3.0 μm in effective radius to 1.0–1.5 μm. However, at a given altitude, the ice particle size often varies through the year. Ice particle sizes in the tropics follow a different seasonal cycle than ice mixing ratio. North polar clouds have a complex seasonal cycle, with a sloped size profile with altitude as the polar hood cloud forms in early fall trending to a roughly uniform 1.5‐μm profile by the end of winter. These data are an important metric to validate and improve general circulation model microphysical routines and to better understand how Martian water ice clouds influence the atmospheric radiative budget.