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

[摘要] Climate models predict an intensification of precipitation extremes as a result of a warmer and moister atmosphere at the rate of 7 % K −1 . However, observations in tropical regions show contrastingly negative precipitation–temperature scaling at temperatures above 23–25  ∘ 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 precipitationevents make observed temperatures covary with precipitation, with wetterperiods and heavier precipitation having a stronger cooling effect. Weremove this confounding effect of clouds from temperatures using a surfaceenergy balance approach constrained by thermodynamics. We then find adiametric change in precipitation scaling with rates becoming positive andcoming closer to the Clausius–Clapeyron (CC) scaling rate (7 % K −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.

[学科分类] 妇产科学