A Classification of Cirrus Ice Crystal Habits with Combined Lidar and Polarimeter Data

Cirrus clouds permanently cover almost half of the Earth’s surface and impact the global climate system through their role in the radiative budget. A better understanding of cirrus microphysical properties, especially the shape and size of ice crystals, is necessary to more accurately quantify their effects on the climate system.

Coincident Cloud Physics Lidar (CPL) and Research Scanning Polarimeter (RSP) aircraft data were collected during the Studies of Emissions and Atmospheric Composition, Clouds and Climate Coupling (SEAC⁴RS) campaign. Airborne polarimeters such as the Research Scanning Polarimeter (RSP) enable the retrieval of cirrus microphysical properties by measuring the radiance and state of polarization of light. TheCPL flown onboard NASA’s ER-2 aircraft uses backscatter and depolarization products at multiple wavelengths to classify clouds and aerosols with high temporal and spatial resolutions. In this study, using combined lidar and polarimeter observations from CPL and RSP, the relationships between ice crystal microphysical and optical properties are studied and are further used to develop methods for classifying the shape of ice crystals in cirrus.