Highland barley is the unique germplasm resource and dominant crop in Tibet with low-level precipitation and a severe shortage of available water resources. Understanding the characteristics and dynamics of evapotranspiration (ET) components (vegetation transpiration (Ec), soil evaporation (Es), and canopy interception evaporation (Ei)) of highland barley can help better optimize water management practices. The seasonal and interannual variations in ET components of highland barley were investigated using the PML-V2 ET product during 2001–2020. The results suggested that Es was the most important ET component and accounted for 77% of total ET for highland barley in Tibet. ET components varied obviously over the altitude, Es, and Es/ET ratio; a decreasing trend was observed with the increase in altitude from 3500 m to 3800 m and then this changed to an increasing trend until reaching the altitude of 4100 m, while Ec, Ei, and their ratios presented an opposite changing pattern to that of Es. Seasonal variation in daily ET components of highland barley displayed a parabolic pattern, peaked in August, while the temporal distributions differed considerably among different ET component ratios. The seasonal variations in ET components were correlated significantly with air temperature, relative humidity, and precipitation, while ET components ratios were more influenced by the environment, irrigation practice, and management rather than meteorological variables. Es and its ratio in highland barley decreased significantly during 2001–2020, while the Ec/ET ratio generally showed an opposite trend to the Es/ET ratio, and Ei and its ratio presented an insignificantly decreasing trend. The interannual variations in ET components were not correlated significantly with meteorological variables, while Ei was more influenced by meteorological variables, especially the precipitation characteristics.

The evaporation of intercepted precipitation (Ei) is an important component of evapotranspiration. Investigating the spatial and temporal variations of Ei and its driving factors can improve our understanding of water and energy balance in the context of China’s greening. This study investigated the spatial and temporal variation of Ei across China during 2001−2020 using PML ET product with a temporal resolution of 8 days and a spatial resolution of 500 m. The results showed that Ei generally decreased from southeast to northwest, which was contributed by the coupled effect of precipitation and vegetation coverage variation across China. Generally, Ei showed an increasing trend over the last two decades with an average changing rate of 0.45 mm/year. The changing rate varied greatly among different regions, with the most obvious change occurring in tropical and humid regions. Precipitation was the most important climatic factor driving the interannual change of Ei over the past two decades, with an average contribution rate of 30.18~37.59%. Relative humidity was the second most important climatic factor following precipitation. Temperature showed contracting contribution in different thermal regions. The contribution rates of NDVI and LAI followed a similar spatial pattern. Both the contribution rates of NDVI and LAI generally increased along the moisture gradient from east to west and generally increased from south to north.