Causes for asymmetric warming of sub-diurnal temperature responding to global warming

Defined as the difference between the daily maximum (T-max) and minimum surface air temperature (T-min), 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 T-min, and the lower in T-max. This asymmetry results in the DTR reduction of 0.5 degrees K in the mid-latitude and 0.25 degrees K in the low-altitude area (under 2 degrees 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 T-max "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.