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	Two Improvements of an Operational Two-Layer Model for Terrestrial Surface Heat Flux Retrieval
	Tian J.; Xia J.
	2008
关键词	Two-layer model surface evapotranspiration surface energy balance Bowen Radio trapezoid method remote-sensing model water-use efficiency north china plain triangle method vegetation index air-temperature regional-scale energy fluxes soil evapotranspiration
英文摘要	In order to make the prediction of land surface heat fluxes more robust, two improvements were made to an operational two-layer model proposed previously by Zhang. These improvements are: 1) a surface energy balance method is used to determine the theoretical boundary lines (namely 'true wet/cool edge' and 'true dry/warm edge' in the trapezoid) in the scatter plot for the surface temperature versus the fractional vegetation cover in mixed pixels; 2) a new assumption that the slope of the T(m) - f curves is mainly controlled by soil water content is introduced. The variables required by the improved method include near surface vapor pressure, air temperature, surface resistance, aerodynamic resistance, fractional vegetation cover, surface temperature and net radiation. The model predictions from the improved model were assessed in this study by in situ measurements, which show that the total latent heat flux from the soil and vegetation are in close agreement with the in situ measurement with an RMSE (Root Mean Square Error) ranging from 30 w/m(2)similar to 50 w/m(2), which is consistent with the site scale measurement of latent heat flux. Because soil evaporation and vegetation transpiration are not measured separately from the field site, in situ measured CO(2) flux is used to examine the modeled. lambda E(veg). Similar trends of seasonal variations of vegetation were found for the canopy transpiration retrievals and in situ CO(2) flux measurements. The above differences are mainly caused by 1) the scale disparity between the field measurement and the MODIS observation; 2) the non-closure problem of the surface energy balance from the surface fluxes observations themselves. The improved method was successfully used to predict the component surface heat fluxes from the soil and vegetation and it provides a promising approach to study the canopy transpiration and the soil evaporation quantitatively during the rapid growing season of winter wheat in northern China.
出处	Sensors
卷	8
期	10
页	6165-6187
收录类别	SCI
语种	英语
ISSN号	1424-8220
内容类型	SCI/SSCI论文
源URL	[http://ir.igsnrr.ac.cn/handle/311030/22370]
专题	地理科学与资源研究所_历年回溯文献
推荐引用方式 GB/T 7714	Tian J.,Xia J.. Two Improvements of an Operational Two-Layer Model for Terrestrial Surface Heat Flux Retrieval. 2008.

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