中文摘要：

利用2009年6-8月兰州大学半干旱气候与环境观测站（SACOL）的地表辐射观测资料,近地层大气温度、湿度和水平风速的三层梯度观测资料,以及热通量的涡动相关观测,比较了变分法估算的地表热通量与涡动相关观测值间差异,评估了不同相似函数对变分法估算地表热通量的影响。结果表明,变分法估算的地表热通量在时间变化趋势上与涡动相关观测值一致,但在中午前后时段还存在数值大小差异。不同相似函数对变分法估算热通量的影响不一样：当层结不稳定时,其对热通量估算的影响较大;当层结不稳定变弱时,影响会显著变小;当层结稳定时,影响非常小,与观测误差相比可以忽略。

英文摘要：

Using the surface heat fluxes data observed by eddy covariance（EC） method,radiation observation data,three heights of wind,humidity and temperature observation data in Semi-Arid Climate and Environment Observatory of Lanzhou University（SACOL） during June,July and August 2009,the fluxes estimated by variational method were compared against those observed by EC method and also the effects were investigated on estimated heat fluxes when using the different similarity functions in the variational method.The results show that the heat fluxes estimated by the variational method generally have the same temporal changes as those from EC method but difference exist during time periods around midday.The performances are different by using the different similarity functions with the variational method： In the unstable conditions,the different similarity functions has a great effect on heat flux estimation,however,the impact will significantly reduce when the unstable condition become weak;under the stable conditions,the effect is very small on heat flux estimation by using the different similarity functions so it could be ignored as compared with the observational errors.