Temporal Variations in the Surface Soil Heat Flux over Maize and Grass Surfaces in Northwest China

作者:Li, NN (Li, Nana)[ 1,2 ] ; Jiang, L (Jiang, Lei)[ 3,4 ]

SOIL SCIENCE SOCIETY OF AMERICA JOURNAL

卷: 79  期: 4  页: 1084-1093

DOI: 10.2136/sssaj2014.11.0439

出版年: JUL-AUG 2015

摘要

Surface soil heat flux (G(0)) is an indispensable component of the surface energy balance (SEB) and is important for estimating instantaneous surface evapotranspiration (ET). Many studies suggest that daily or longer timescales of G(0) can be ignored, whereas other studies suggest the opposite. In this study, a long-term G(0) was calculated using a heat conduction equation based on observed soil temperature and moisture profiles over 30-min intervals from January 2008 to December 2011. Maize and meadows covered the study area in the Heihe River Basin (HRB), northwestern China. The effects of various timescales of G(0) (half-hourly, daily, monthly, and yearly) on energy balance closure (EBC) and ET estimations were quantitatively analyzed. The results showed that the diurnal G(0) had the same magnitude as the sensible heat flux, and it increased the EBC by 12.9 and 8.2% in maize and grasslands, respectively. The maximum daily G(0) reached 20% of the net radiation, and the maximum monthly ET was overestimated by 15% when neglecting the monthly G(0) over the bare soil when the maize has not germinated. The yearly G(0) values were nearly zero in maize and grasslands and were excluded. Thus, the G(0) is important for EBC and ET estimation with shorter timescale than annual timescale. The G(0) should not be neglected except for annual timescale.

通讯作者地址: Jiang, L (通讯作者)

Nanjing Univ Informat Sci & Technol, Sch Marine Sci, Nanjing 210044, Jiangsu, Peoples R China.

地址:

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

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

[ 3 ] Nanjing Univ Informat Sci & Technol, Sch Marine Sci, Nanjing 210044, Jiangsu, Peoples R China

[ 4 ] Jiangsu Engn Technol Res Ctr Marine Environm Dete, Nanjing, Jiangsu, Peoples R China