基于土壤温湿度观测资料估算藏北高原地区土壤热通量

Estimation of Soil Heat Flux over the Northern Tibetan Plateau based on in-situ Soil Temperature and Moisture Data

基于"全球协调加强观测计划(CEOP)亚澳季风之青藏高原试验研究"(CAMP/Tibet)土壤温湿度观测资料(2004年6月8日至7月30日),利用TDEC(土壤温度预报校正)法估算并分析了藏北高原地区土壤热通量的变化特征。通过与热通量板测量结果比较发现,它们在热流方向和相位上基本一致,且在量值上具有很好的线性关系(R^2>0.74),但热通量板测量值普遍偏小。通过对比不同天气条件下TDEC法的估算结果表明,云的存在以及降水发生都可导致土壤热通量的波动,且表层土壤热通量波动更加强烈。对于TDEC法估算的表层土壤热通量,发现它与净辐射通量线性关系密切(R2>0.78),而在土壤热传导率较大的地区,其日变化相位明显先于其他地区。对于土质均匀的砂质土壤,其土壤热通量日变化振幅最大,土壤的垂直热量交换最剧烈。

In order to estimate and analyze soil heat flux over the Northern Tibetan Plateau,this study adopts a temperature prediction- correction（TDEC）method based on in- situ soil temperature and moisture data（from 8June to 30 July 2004）from the Coordinated Enhanced Observing Period（CEOP）Asia-Australia Monsoon Project on the Tibetan Plateau（CAMP/Tibet）. The comparison between in- situ soil heat flux and estimated values from TDEC shows that they have the same heat flux flow direction and phase. A positive linear relationship（R20. 74）can also been found between them,but the in-situ values by heat flux plate is generally smaller than estimation. Both cloud and precipitation can influence the fluctuation of soil heat flux,especially in the surface soil.A good linear relationship（R2 0. 78）exists between ground heat flux calculated by the TDEC method and the net radiation flux. The higher soil thermal conductivity,the faster diurnal variation rate of soil heat flux estimated by the TDEC method. For homogeneous sandy loam soil,the diurnal variation amplitude of soil heat flux is very large,indicating the vertical heat exchanged is very strong.