The daily average ground surface soil heat flux (G_{0_daily}) has been widely applied in land surface models. The accuracy of modeling G_{0_daily} greatly impacts the estimation of the evapotranspiration and heat and moisture exchanges between the atmosphere and ground surface in frozen ground regions. We propose two methods for estimating G_{0_daily} over the Qinghai-Tibet Plateau (QTP): the combination method (CM) and the sine method (SM). The instantaneous surface soil heat flux (G_{0_ins}) is estimated at multiple times per day using the CM, and then, G_{0_daily} is obtained. The SM simulates G_{0_daily} by estimating G_{0_ins} during the satellite transit based on the diurnal variation in the sinusoidal curves of G_{0_ins} under clear-sky conditions. For G_{0_ins}, the root mean square error (RMSE) and coefficient of determination (R²) of the CM are more than 10 W/m² lower and 0.12 higher than those of the surface energy balance system (SEBS), respectively. For G_{0_daily}, at the four sites (TGLMS, Naqu, Biru, and Nierong), the RMSE and the correlation coefficient (R) values of the CM are better than those of the SM by –0.86 W/m², 9.04 W/m², 4.33 W/m², and 2.55 W/m² and 0.19, 0.12, 0.10, and 0.08, respectively. The CM is applicable under all weather conditions and multi-period and multi-parameter observations throughout a day. Due to the principle of the SM, it can only simulate G_{0_daily} when the satellite observes at least once each in the daytime and nighttime under clear-sky conditions. The SM overcomes the shortcomings of the CM, i.e., the requirements of complex input parameters and a large data volume. The advantage of the high spatial resolution of polar-orbiting satellite remotely sensed data (such as Moderate Resolution Imaging Spectroradiometer (MODIS) data) is given full play by the SM.

日平均地表土壤热通量（G _{0_daily}）已广泛应用于地表模型。G _{0_daily}建模的准确性极大地影响了冻土区大气与地表之间蒸发蒸腾和热湿交换的估计。我们提出了两种估算青藏高原（QTP）G _{0_daily的方法：组合法（CM）和正弦法（SM）。}利用CM每天多次估算瞬时地表土壤热通量（G _{0_ins} ），然后得到G _{0_daily 。}SM通过估计来模拟G _{0_daily}基于晴空条件下G _{0_ins}正弦曲线的日变化，卫星凌日期间的G _{0_ins 。}对于G _{0_ins} ， CM 的均方根误差 (RMSE) 和确定系数 ( R ² )分别比表面能量平衡系统 (SEBS) 低10 W/m ^{2以上和高 0.12 以上。}对于G _{0_daily}，在TGLMS、那曲、碧如和聂荣这四个站点，CM的RMSE和相关系数（R）值比SM好–0.86 W/m ²、9.04 W/米² , 4.33 瓦/米², 和 2.55 W/m ²和 0.19, 0.12, 0.10, 和 0.08, 分别。CM适用于全天候全天候多时段多参数观测。由于SM的原理，它只能模拟G _{0_daily}当卫星在晴空条件下白天和夜间至少各观测一次。SM克服了CM要求输入参数复杂、数据量大的缺点。SM充分发挥了极轨卫星遥感数据（如中分辨率成像光谱仪（MODIS）数据）空间分辨率高的优势。