Radiation as the dominant cause of high-temperature extremes on the eastern Tibetan Plateau

Abstract

Temperature extremes have been related to anomalies in large-scale circulation, but how these alter the surface energy balance is less clear. Here, we attributed high extremes in daytime and nighttime temperatures of the eastern Tibetan Plateau (ETP) to anomalies in the surface energy balance. We find that daytime high-temperature extremes are mainly caused by altered solar radiation, while nighttime ones are controlled by changes in downwelling longwave radiation. These radiation changes are largely controlled by cloud variations, which are further associated with certain large-scale circulations that modulate vertical air motion and horizontal cloud convergence. In addition, driven by a high-pressure system, strengthened downward solar radiation tends to decrease the snow albedo, which then plays an important role in reducing upward solar radiation, especially during winter and for compounding warm events. The results during winter and summer are generally similar but also present significant differences in terms of the contribution of variations in snow albedo, surface turbulent fluxes, and horizontal advection of cloud, which hence need further attention in simulating the high-temperature extreme events in the ETP. Our work indicates the importance to attribute different temperature extremes separately from the perspective of energy balance.

Keywords

• temperature extremes
• physical causality
• surface energy balance
• radiation
• land–atmosphere interaction