The vertical distribution of Martian aerosol particle size

Abstract

Using approximately 410 limb-viewing observations from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM), we retrieve the vertical distribution of Martian dust and water ice aerosol particle sizes. We find that dust particles have an effective radius of 1.0 μm over much of the atmospheric column below 40 km throughout the Martian year. This includes the detached tropical dust layers detected in previous studies. Little to no variation with height is seen in dust particle size. Water ice clouds within the aphelion cloud belt exhibit a strong sorting of particle size with height, however, and the effective radii range from >3 μm below 20 km to near 1.0 μm at 40 km altitude. Conversely, water ice clouds in the seasonal polar hoods show a near-uniform particle size with an effective radius of approximately 1.5 μm throughout the atmospheric column.