Contributors to the Elevation-Dependent Warming over the Tibetan Plateau in the CORDEX-EA-II simulations

Abstract

To explore the driving mechanisms of elevation-dependent warming (EDW) over the Tibetan Plateau (TP), the output from a suite of numerical regional climate models (RCMs) under the Coordinated Regional Climate Downscaling Experiments-East Asia (CORDEX-EA-II) project is examined. Results show that all RCMs can broadly capture the observed temperature distributions over the TP with consistent cold biases, and the spread in temperature simulations could to a large extent be explained by their spreads in the surface albedo feedback (SAF). The simulated EDW during winter is mainly caused by the SAF, and the clear-sky downward longwave radiation (LW) plays a secondary role in shaping EDW. Further analysis suggests that a marked EDW signal over the TP is simulated under the Representative Concentration Pathway emission scenario 8.5 (RCP8.5) for all seasons, particularly in autumn, and the SAF is also the primary contributor to EDW and acts as the main source of uncertainty in EDW projections among RCMs. The LW is the dominant factor in regulating the surface air temperature change over the TP, and its contribution to EDW is model-dependent. Furthermore, the structure and magnitude of projected EDW are sensitive to the RCM physics and driving GCM, as they can alter the projections of snow cover and albedo, which modulate the simulated SAF and its effect on EDW.