作者:Li, NN (Li NaNa)[ 1,2 ] ; Jia, L (Jia Li)[ 1,3 ] ; Lu, J (Lu Jing)[ 1 ]

SCIENCE CHINA-EARTH SCIENCES

卷: 58  期: 7  页: 1169-1181

DOI: 10.1007/s11430-014-5041-y

出版年: JUL 2015

摘要

Surface soil heat flux (G(0)) is an indispensable component of the surface energy balance and plays an important role in the estimation of surface evapotranspiration (ET). This study calculated G(0) in the Heihe River Basin based on the thermal diffusion equation, using the observed soil temperature and moisture profiles, with the aim to analyze the spatial-temporal variations of G(0) over the heterogeneous area (with alpine grassland, farmland, and forest). The soil ice content was estimated by the difference in liquid soil water content before and after the melting of the frozen soil and its impact on the calculation of G(0) was further analyzed. The results show that: (1) the diurnal variation of G(0) is obvious under different underlying surfaces in the Heihe River Basin, and the time when the daily maximum value of G(0) occurs is a few minutes to several hours earlier than that of the net radiation flux, which is related to the soil texture, soil moisture, soil thermal properties, and the vegetation coverage; (2) the net radiation flux varies with season and reaches the maximum in summer and the minimum in winter, whereas G(0) reaches the maximum in spring rather than in summer, because more vegetation in summer hinders energy transfer into the soil; (3) the proportions of G(0) to the net radiation flux are different with seasons and surface types, and the mean values in January are 25.6% at the Arou site, 22.9% at the Yingke site and 4.3% at the Guantan site, whereas the values in July are 2.3%, 1.6% and 0.3%, respectively; and (4) G(0) increases when the soil ice content is included in thermal diffusion equation, which improves the surface energy balance closure by 4.3%.

通讯作者地址: Jia, L (通讯作者)

       Chinese Acad Sci, Inst Remote Sensing & Digital Earth, State Key Lab Remote Sensing Sci, Beijing 100101, Peoples R China.

地址:

       [ 1 ] Chinese Acad Sci, Inst Remote Sensing & Digital Earth, State Key Lab Remote Sensing Sci, Beijing 100101, Peoples R China

       [ 2 ] Univ Chinese Acad Sci, Beijing 100049, Peoples R China

       [ 3 ] Joint Ctr Global Changes Studies, Beijing 100875, Peoples R China