Sensitivity Analysis of Potential Evapotranspiration in Northeast China

Based on meteorological data from 106 stations in Northeast China from 1960 to 2020, this study calculated potential evapotranspiration ( ET₀ ) using the Penman-Monteith formula. The research area was divided into four subregions using the K-means clustering method, revealing the sensitivity responses and contribution rates of different meteorological factors to ET₀ changes under climate change. The results are as follows: Daily mean temperature (TEM) significantly increased in all four subregions, while wind speed (WIND) significantly decreased. Relative humidity (RH) and sunshine duration (SSD) showed slight declining trends. ET₀ changes exhibited regional differences: a slight decrease in Subregion I and eastern Subregion II, a significant increase in western Subregion II, no significant trend in Subregion III, and a significant increase in Subregion IV. Sensitivity coefficients for all subregions were higher in the south and lower in the north. The sensitivity coefficient for RH was negative, while those for sunshine duration and WIND were positive. Mean temperature sensitivity coefficients were positive except in Subregion IV, where the anomaly may be regulated by high-latitude factors. The decline in RH was the dominant factor driving ET₀ changes in Subregions III and IV. In Subregions I and II, ET₀ changes may also be influenced by non-climatic factors or other meteorological variables. This study clarifies the dominant driving factors of evapotranspiration changes in each region, providing a theoretical basis for optimizing agro-hydrological models in cold regions and supporting regional agricultural water consumption assessment and water resource optimization.