卫星遥感结合地面观测估算中国西北区东部地表能量通量

采用定西麦田微气象观测站和试验区其它地区36个自动气象站、91个常规气象站资料,结合NOAA-16卫星的AVHRR资料,用地表能量平衡算法(SEBAL)推导中国西北区东部4~8月的日平均地表净辐射、感热、潜热、土壤热通量密度和波文比的区域分布特征,并按土地覆盖类型的不同分别统计沿黄灌区、冬春小麦雨养农田、草地、森林和沼泽草甸等不同地表的能量通量特征。结果显示:作物不同生育期,自南向北由湿润的常绿林区经半干旱雨养农业区直到干旱的荒漠地带,地表能量输送存在巨大的地区差异。计算结果与实测值之间的平均绝对百分误差为4%~21%,两者基本相符,该方法在算法上解决了用卫星资料反演地气温差的难点问题,提高了感热通量区域分布的计算精度。

Estimation of land surface energy flux densities over eastern part of Northwest China with the aid of satellite remote sensing and field observations

In this paper,the regional distribution features of the land surface daily mean net radiation flux density,sensible heat flux,latent heat flux,soil heat flux and Bowen ratio during April-August over eastern part of Northwest China are derived from the Surface Energy Balance Algorithm for Land(SEBAL),that are aided combining micrometeorological observations over a wheat field at Dingxi station and observations data of 36 automatic and 89 routine weather stations over experimental region with NOAA-16 AVHRR data.Based on land classification the energy flux densities of variant land surface such as the Yellow River irrigated paddy field,spring wheat field,winter wheat field,grass land,forest and marsh land have been estimated.It is shown that the variant growing periods of plants from the south humid evergreen forest through the semi-arid rainfed agriculture region into the north arid desert land surface energy transport are much different.The mean absolute percent difference between the derived results and measured values at Dingxi station is between 4% and 21%.The differences between surface temperature and air temperature(T_s-T_a) are sensitive for calculated sensible heat flux. A fitted relationship between (T_s-T_a) and(T_s,NDVI,Z) was found.The retrievals of regional (T_s-T_a) can be derived using satellite data.A difficult problem in calculation was solved,which can improve the estimation of regional sensible heat flux.