在全球变暖的背景下， 青藏高原通过感热加热和潜热释放改变大气环流， 不仅影响高原生态系统的水分收支平衡与能量平衡， 还对亚洲乃至全球气候起着重要的调节作用。为探究青藏高原高寒草地生态系统蒸散发在不同区域的变化特征及影响因子， 加深对高原气候变化的理解和生态水文过程的了解， 基于2022年观测到的涡动及气象资料， 对比分析了思金拉措（季节冻土）、 沱沱河（多年冻土）两地相同海拔处的高寒草地生态系统实际蒸散发量的变化特征及环境影响因素。结果表明： （1）两地环境因子相差较大的是风速、 空气温度、 降雨量， 沱沱河站风速远大于思金拉措站； 年均气温、 降雨量均低于思金拉措站。（2）思金拉措站夜间蒸散发日内小时平均值大于沱沱河站， 白天则相反； 两站日蒸散量变化趋势特征相近， 思金拉措站蒸散量急剧增大时间和最大值出现时间均早于沱沱河站； 两站月蒸散量均为单峰型， 夏季7月蒸散量最大， 冬季12月、 1月、 2月较小。（3）风速、 大地辐射在两站与蒸散量具有不同的相关性， 风速在沱沱河站较大， 与蒸散发相关性较强， 在思金拉措站风速小， 两者相关性较弱， 大地辐射在两地与蒸散发的相关性则正好相反； 在两地与蒸散量相关性均较大的是空气温度、 水汽压、 大气逆辐射， 均较弱的是空气湿度、 饱和水汽压差， 最弱的是降雨。（4）降雨虽然是蒸散水分的主要来源， 但在青藏高原， 冰川冻土融水也是蒸散水份的重要来源， 因此降雨对两地蒸散发量影响较小。

In the context of global warming， the Qinghai-Xizang Plateau is altering atmospheric circulation through sensible heat absorption and latent heat release.This not only impacts the water and energy balance of the plateau's ecosystem but also plays a crucial role in regulating Asian and global climates.In order to explore the change characteristics and influencing factors of evapotranspiration in different regions of alpine grassland ecosystem on the Qinghai-Xizang Plateau， and deepen understanding of plateau climate change and hydrological-ecological processes， based on the observed eddy and meteorological data in 2022， the variation characteristics and environmental influencing factors of actual evapotranspiration of alpine grassland ecosystems at the same altitude in Sijinlacuo （seasonal permafrost） and Tuotuo River （permafrost） on the Qinghai-Xizang Plateau were compared and analyzed.The results show that： （1） Significant differences existed between environmental factors at these two sites， particularly in wind speed， air temperature， and precipitation.The wind speed at Tuotuo River station greatly exceeded that at Shijinlasuo station； annual average air temperature and precipitation were lower at Tuotuo River station.（2） The average hourly evapotranspiration of Sijinlacuo Station at night was higher than those recorded at Tuotuo River Station， however， this trend reverses during daytime hours.The variation characteristics of daily evapotranspiration at the two stations had a similar trend.The date of sharp increase and maximum of evapotranspiration at Sijinlacuo Station were earlier than those at Tuotuo River Station.The monthly evapotranspiration of the two stations were unimodal， with the maximum value appeared in July in summer and the smaller value appeared in December， January and February in winter.（3） Wind speed and ground radiation showed differing correlations with evaporation across both stations.Wind speed had a stronger correlation with evaporation at Tuotuo River Station due to higher wind speeds compared to weaker correlations observed for Sijinlasuo Station where winds were less intense.Conversely， ground radiation showed opposite correlations with evaporation between both locations.Air temperature， water vapor pressure， and atmospheric longwave radiation demonstrated strong correlations with evaporation across both locations while air humidity， saturated water vapor pressure difference， and precipitation displayed weaker associations.Precipitation exhibited the weakest correlation.（4） Although precipitation served as the primary source of evaporated water content， sources such as glacier melt water and thawing permafrost played significant roles as well on the Qinghai-Xizang Plateau， resulting in subdued influence of precipitation on the evaporative process at both locations.These results contribute valuable insights into understanding regional variations in high-altitude grassland ecosystems' response to changing climatic conditions on the Qinghai-Xizang Plateau.