中国潜在蒸散发趋势转折与气象因子作用分析OA

To elucidate the non-linear evolution characteristics of regional potential evapotranspiration(PET)in China under climate change,and specifically to quantify the often-overlooked physiological regulation effect of elevated atmospheric CO2 concentrations,this study employed high-precision meteorological data from 1961 to 2022 to calculate PET using an improved FAO Penman-Monteith(FAO-PM)equation that incorporates a CO2 stomatal resistance mechanism.A segmented model and a sensitivity attribution method were employed to accurately identify the trend turning points of PET and dissect its underlying driving mechanisms.The results indicate the following:1)The trend of annual PET in China exhibited a distinct turning point in 1998,shifting from a significant decrease(-3.10 mm/a)during 1961-1998 to a marked increase(7.57 mm/a)during 1998-2022;2)PET was most sensitive to changes in relative humidity(sensitivity coefficient of-1.57),followed by air temperature and wind speed;3)The attribution analysis revealed phased differences in the driving mechanisms.The decrease in PET before 1998 was primarily driven by declining wind speeds(-13.45％contribution),which offset the positive effects of rising temperatures.Conversely,the surge in PET after 1998 was mainly driven by a significant decline in relative humidity(18.87％contribution),with rebounding wind speeds and rising temperatures acting as synergistic amplifiers;4)Regardless of the overarching PET trend,the continuous elevation of atmospheric CO2 concentrations consistently generated a negative effect(-1.77％and-1.71％)via the stomatal regulation mechanism,partially offsetting the increased evaporative demand induced by climate warming.This study confirms that the evolution of PET in China has undergone a dynamic mechanism shift from a"wind speed-dominated decrease"to a"humidity-dominated increase".