First Investigations of Drizzling Boundary Layer Cloud Properties with OCO-2 A-band Retrievals

Our new OCO2CLD-LIDAR-AUX product retrieves marine boundary layer cloud optical depth (τ) & geometric thickness (H) using OCO-2's hyperspectral oxygen A-band sensor with cloud-top constraints from CALIPSO's lidar. This retrieval responds to within-cloud photon path lengths so is independent of MODIS-based estimates which typically link and effective radius through a sub-adiabatic cloud model with many assumed parameters. We detect geometric thickening of drizzling clouds relative to a standard sub-adiabatic cloud model, these differences in H for CloudSat-identified drizzling clouds are promising for the use of hyperspectral A-band measurements as a new constraint on low cloud properties.