Spatiotemporal dynamics and key drivers of potential evapotranspiration across the Yangtze River Basin from 1975 to 2018

As a representative indicator of atmospheric evapotranspiration capacity, potential evapotranspiration (ET0) is of paramount importance for understanding the mechanisms in the process of water-energy exchange. Focusing on the Yangtze River Basin (YZRB) as the research region, this paper investigated the spatiotemporal pattern of ET0 and the formation mechanism behind it by synthetic approaches. Based on the ET0 dataset, the sensitivity analysis was conducted to quantitatively assess the influence of meteorological factors on the temporal variation of ET0. Furthermore, the Multiscale Geographically Weighted Regression (MGWR) model was implemented to investigate the driving force resulting in the spatial distribution in ET0. The results show that: (1) The average multi-year ET0 from 1975 to 2018 was about 930 mm, with a trend of 0.63 mm/yr. (2) Temperature (T) was the primary factor affecting the spatial pattern of ET0 except in spring, with MGWR regression coefficients of 0.466 and above 0.60 on annual and seasonal scales, respectively. (3) Solar radiation (RS) had the greatest effect on the temporal variation of ET0, especially in the summer when the sensitivity of ET0 to RS generally exceeded 1.00. This study accurately identified the spatiotemporal variations and causes of ET0 in the YZRB, which can offer valuable insights for addressing hydrological challenges on large scales.