Synopsis:

Clouds are one of the largest contributors to climate change and the least understood. While it is well-known that the cloud droplet size distribution (DSD) controls many of the growth and radiative processes in clouds, DSDs are difficult to measure from space. New polarimeter instruments, like the Hyper-Angular Rainbow Polarimeter (HARP), can access the entire DSD for different clouds using a special cloud feature that only appears in polarized light. Therefore, HARP-like instruments are needed in future space missions, such as NASA Plankton-Aerosol-Cloud-ocean Ecosystem (PACE) and Aerosol & Cloud, Convection and Precipitation (A&CCP), to validate of current ones (MODIS, VIIRS, ABI), and improve our climate predictions. This work compared the HARP measurement of real clouds with simulated HARP measurements over large-eddy simulated (LES) cloud fields. The goal was to better understand the relationships between the polarized scattering and the DSD properties of clouds, as well as validate HARP field measurements at different resolutions.