Contrasting Effect of Spring Snowmelt on Early Summer Surface Air Temperature Over Western and Central Tibetan Plateau

The thermal anomaly over the Tibetan Plateau (TP) can exert extensive impacts on the various aspects of the Earth system. Although multiple mechanisms were proposed to explain the rapid increase of surface air temperature (SAT) over the TP, the causes of interannual variability of SAT have received little concern as yet. This study reveals an opposite effect of spring snowmelt on the local early summer SAT over western and central TP. Specifically, the spring snowmelt over the western TP is positively correlated with SAT in June and July, while a negative correlation is seen between spring snowmelt and June SAT over the central TP. Further analyses indicate that spring snowmelt over the western TP has little impact on the local soil moisture because the soil is still frozen. Instead, the snow‐albedo effect works effectively over there. More spring snowmelt leads to the reduced snow cover and surface albedo during June and July, which increases surface net shortwave radiation and enhances energy transfer from land to atmosphere, ultimately raising the SAT. In contrast, owing to the relatively warmer background climate over the central TP, the snow cover has almost completely melted by spring, favouring the operation of the delayed snow‐hydrological effect. The enhanced spring snowmelt would cause increased soil moisture that can persist until June, and then consume more surface energy for evaporation, thereby leading to the lower SAT. Our findings highlight the important role of background climate in the divergent snow‐atmosphere coupling processes and provide the theoretical basis for better predicting the summer SAT over the TP.