The changing relationship between precipitation efficiency and global precipitation

Precipitation efficiency (PE) is the relationship between cloud condensation and precipitation that links the atmospheric circulation to the hydrological cycle. Definition and thus, estimates vary greatly due to the underlying microphysical dependencies of PE. It also quantifies the fraction of condensed water in clouds that falls as surface precipitation. Consequently, there is a dearth of knowledge about the sensitivity of PE to the global warming and its subsequent implications for climate change. Therefore, here, we estimate the global PE based on the surface precipitation and cloud water path1 , and quantify its role in the variability and changes in precipitation in the climate change context using the Moderate Resolution Imaging Spectroradiometer (MODIS) and Global Precipitation Measurement (GPM) observations for the period of 2001–2020. We find that the annul mean PE is very high in the tropics, including both the West Pacific and Indian Ocean Warm Pool. Other regions in the tropics, like Amazonia and Central Africa also show very high PE values. These regions also have very high surface precipitation. There is gradual decline in PE in the tropics in the last decade (2010–2020), which is consistent with the decreasing trend of precipitation there. Regions such as the warm pool, Northeast India and Amazonia show a decreasing pattern in both PE and precipitation in the past decade. This decline in both PE and precipitation in the tropics suggests that, a fraction of condensed water falls as precipitation decreases. On the other hand, there is notable rise in temperature in the tropics during the same period. However, the quantification of the sensitivity of PE to global warming on a regional scale is very critical.