蒸散发是水文循环和地表能量平衡的关键组成部分，对于水资源的有效管理、干旱情况的监测以及农业生产的优化均有着不可或缺的作用。选取红碱淖流域为研究区，基于Landsat8遥感数据，结合地表能量平衡系统（surface energy balance system, SEBS）模型，估算了流域内2019年的6个日期的日蒸散发量，并对其进行了验证。通过对蒸散发的时空变化趋势和影响因素进行分析，获得结果表明：通过SEBS模型估算的日实际蒸散发量与通过Penman-Monteith（P-M）公式估算的潜在蒸散发量，以及气象站蒸发皿实际观测的蒸散发量的拟合优度R²分别为0.84（P < 0.01）、0.602（P < 0.05），验证了SEBS模型在红碱淖流域的蒸散发量估算中具有较高的准确性和可靠性。红碱淖流域日蒸散发量呈现出明显的季节差异，夏季最高，春季次之，秋季再次，而冬季最低。流域东部红碱淖水体和流域西部查干淖尔及其周边区域的蒸散发量相对较高。流域中部蒸散发量相对较低。不同的土地利用类型中，水体的蒸散发量最高，其次是林地、耕地、建设用地、草地，最低的是未利用地。气象因素中，气温、气压和日照时数是主要影响因素，分别与蒸散发量呈显著正相关（r ＝ 0.847，P < 0.05）、负相关（r ＝ -0.840，P < 0.05）和正相关（r ＝ 0.801，P < 0.05），而相对湿度和风速与蒸散发量相关性较弱。

Evapotranspiration is considered a crucial part of the hydrological cycle and surface energy balance. It is regarded as indispensable for effective water resource management, drought monitoring, and agricultural production optimization. Based on the Landsat8 remote sensing data and combined with the surface energy balance system (SEBS) model, the daily evaporation in the basin on six dates in 2019 was estimated and verified. By analyzing the spatiotemporal variation trend and influencing factors of evapotranspiration, the obtained results show that the goodness of fit R² between the actual daily evapotranspiration estimated by the SEBS model, the potential evapotranspiration estimated by the Penman-Monteith (P-M) formula, and the evapotranspiration actually observed in the evaporation dish of the meteorological station are 0.84 (P < 0.01) and 0.602 (P < 0.05), respectively. It has been verified that the SEBS model has high accuracy and reliability in the estimation of evapotranspiration in the Hongjiannao River Basin. The daily evapotranspiration in the Hongjiannao River Basin shows obvious seasonal differences, with the highest in summer, followed by spring, then autumn, and the lowest in winter. The evapotranspiration in the Hongjiannao water body in the eastern part of the basin and in the Chagannaoer and its surrounding areas in the western part of the basin is relatively high. The evapotranspiration in the middle of the basin is relatively low. Among different types of land use, the evapotranspiration of water bodies is the highest, followed by forest land, cultivated land, construction land and grassland, and the lowest is unused land. Among meteorological factors, temperature, air pressure and sunshine duration are the main influencing factors, which are significantly positively correlated with evapotranspiration (r=0.847, P < 0.05), negatively correlated with (r = -0.840, P < 0.05) and positively correlated with (r = 0.801, P < 0.05) respectively, while relative humidity and wind speed have relatively weak correlations with evapotranspiration.