Breakdown in precipitation-temperature scaling over India predominantly explained by cloud-driven cooling

Abstract

Climate models predict an intensification of precipitation extremes as a result of a warmer and moister atmosphere at the rate of 7g%gK-1. However, observations in tropical regions show contrastingly negative precipitation-temperature scaling at temperatures above 23-25gg C. We use observations from India and show that this negative scaling can be explained by the radiative effects of clouds on surface temperatures. Cloud radiative cooling during precipitation events make observed temperatures covary with precipitation, with wetter periods and heavier precipitation having a stronger cooling effect. We remove this confounding effect of clouds from temperatures using a surface energy balance approach constrained by thermodynamics. We then find a diametric change in precipitation scaling with rates becoming positive and coming closer to the Clausius-Clapeyron (CC) scaling rate (7g%gK-1). Our findings imply that the intensification of precipitation extremes with warmer temperatures expected with global warming is consistent with observations from tropical regions when the radiative effect of clouds on surface temperatures and the resulting covariation with precipitation is accounted for.