An increasing trend in the ratio of transpiration to total terrestrial evapotranspiration in China from 1982 to 2015 caused by greening and warming

Abstract The ratio of transpiration to total terrestrial evapotranspiration (T/ET) plays an important role in the hydrological cycle and in the energy budgets between the land and the atmosphere. Although China has experienced substantial climate warming and vegetation restoration (i.e., greening) over the past decades, the response of T/ET to the changing climate and environmental factors is poorly understood. Here, we apply a model-data fusion method that integrates the Priestly-Taylor Jet Propulsion Laboratory (PT-JPL) model with multivariate observational datasets (transpiration and evapotranspiration) to quantify the relative contributions of multiple factors to the T/ET trend for the terrestrial ecosystem of China from 1982 to 2015. Validation against the observational data indicates that the PT-JPL model performed well. The multi-year average T/ET was estimated to be 0.56 ± 0.05 in China. The T/ET of the forest ecosystems (0.65–0.72) was generally higher than that of the non-forest ecosystems (0.41–0.60). T/ET increased remarkably at a rate of 0.0019 yr−1 (P