Causes for Asymmetric Warming of Sub-Diurnal Temperature Responding to Global Warming

Abstract

Defined as the difference between the daily maximum (Tmax) and minimum surface air temperature (Tmin), the diurnal temperature range (DTR) is critical to local climate, ecosystem, and socio-economic functioning. This study investigates how DTR responds to the future global warming, using a novel, fine-resolution convection-permitting regional climate model. Results demonstrate the asymmetrical impact of global warming, that is, the more substantial warming in Tmin, and the lower in Tmax. This asymmetry results in the DTR reduction of 0.5°K in the mid-latitude and 0.25°K in the low-altitude area (under 2°K warming scenario). The increase in daytime cloudiness under warmer climates is likely responsible for the reduction of incoming short-wave radiation reduction, consequently causing Tmax “underwarming.” Study results also suggest that atmospheric instability could play a vital role in the difference in DTR response between the tropical and mid-latitude areas.