Biases in Southern Ocean Precipitation From Shallow Convection: The Role of Cloud Morphology

Abstract

Precipitation from marine boundary layer clouds is a critical yet highly uncertain feature of post-frontal conditions over the Southern Ocean (SO), where shallow convection dominates. This study evaluates whether satellite retrievals (GPM-IMERG and CloudSat) and reanalysis (ERA5) represent the contrasting precipitation between open and closed mesoscale cellular convection (MCC) observed over the SO, from limited in situ records. Substantial discrepancies are found across data sets. While ERA5 captures the expected contrast, GPM-IMERG underestimates precipitation, especially from open MCCs, and fails to reflect morphological distinction. Both CloudSat products detect higher mean precipitation..