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

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.

Automated summary

Temperature extremes on the eastern Tibetan Plateau (ETP) are attributed to anomalies in the surface energy balance, with daytime highs primarily caused by changes in solar radiation and nighttime highs controlled by changes in longwave radiation. These radiation changes are influenced by cloud variations, which are in turn associated with large-scale circulations that affect air motion and cloud convergence. The reduction in snow albedo due to increased downward solar radiation plays a significant role in promoting warm events, particularly in winter. While the results are generally similar in winter and summer, there are notable differences in the contributions of snow albedo variations, surface turbulent fluxes, and horizontal advection of cloud, which require further attention in simulating high-temperature extremes in the ETP.