Global precipitation efficiency from a satellite perspective

Abstract

Convective clouds are fundamental to Earth’s climate system, influencing both the global water cycle and planetary radiation budget. However, the processes controlling precipitation efficiency (PE) remain poorly represented in weather models. Because PE links cloud microphysics, storm dynamics, and large-scale radiative feedbacks, understanding its variability across environments is essential. This study examines PE in six regions of intense convection across the tropics and mid-latitudes, using coincident CloudSat and GPM observations combined with an A-Train based Convective Object Database. Key hydrometeor properties, including ice water path, liquid water path, and surface rain rate, are analyzed to quantify PE globally. Results show that PE varies systematically with storm type, environment, and large-scale dynamics, revealing more complexity than simple latitudinal distinctions. While tropical and midlatitude storms differ in cloud structure and hydrometeor loading, these alone do not explain PE variability. Metrics of convective vertical structure, such as relative center of gravity (rCoG), and local shear emerge as key predictors, highlighting the importance of dynamical support and storm maturity.PE also correlates with cloud radiative properties, suggesting that the balance between anvil formationand surface-reaching precipitation is influenced by microphysics affecting both radiative forcing and column water budgets. Comparisons across phases of the Walker circulation indicate that large-scale vertical motion can outweigh latitude in controlling PE. Overall, PE reflects an interplay of mesoscale dynamics, microphysical structure, and global circulations, emphasizing the need to consider lifecycle and environmental context in interpreting convective precipitation efficiency.