Abstract
Elevation plays a crucial role in modulating the spatiotemporal distributions of climatic variables in mountainous regions, which affects water and energy balances, among which reference evapotranspiration (ET 0 ) is a key hydrological indicator. However, the response of ET 0 to climate change with elevation continues to be poorly understood, especially in the Tibetan Plateau (TP) which has elevation variations of more than 4,000 m. The spatiotemporal variations of ET 0 with elevation were investigated using long‐term (1960–2017) meteorological observations from 82 stations on the TP. The results suggest that the average annual ET 0 showed an insignificant increasing trend. A significant negative correlation between ET 0 and elevation was found ( p 0 decreased with elevation, whereas the negative trends of ET 0 increased significantly with elevation ( p 0 becomes smaller at higher‐elevation stations. Sensitivity analysis indicated that ET 0 was most sensitive to shortwave radiation ( R s ). Moreover, the sensitivities of temperature ( T ) and wind speed ( U ) significantly decreased with elevation, whereas those of R s and vapour pressure deficit (VPD) increased slightly with elevation. The contribution and path analyse indicated that increasing VPD was the dominant contributor to the increase in ET 0 . The effect of elevation on ET 0 variation mainly depended on the tradeoff between the contributions of U and VPD. U was the largest contributing factor for the change in ET 0 below 2,500 m, whereas VPD was the primary contributor to the increase in ET 0 above 2,500 m. This study provides insights into the response of ET 0 to climate change with elevation on the TP, which is of great significance to hydrometeorological processes in high‐altitude regions.