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www.hydrol-earth-syst-sci-discuss.net/7/8741/2010/
doi:10.5194/hessd-7-8741-2010
© Author(s) 2010. This work is distributed
under the Creative Commons Attribution 3.0 License.
Measurements of energy and water vapor fluxes over different surfaces in the Heihe River Basin, China
1State key laboratory of Remote Sensing Science, School of Geography, Beijing Normal University, Beijing, 100875, China
2Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou, 730000, China
Abstract. We analyzed the seasonal variations of energy and water vapor fluxes over three different surfaces: irrigated cropland (Yingke, YK), alpine meadow (A'rou, AR), and spruce forest (Guantan, GT). The energy and water vapor fluxes were measured using eddy covariance systems (EC) and a large aperture scintillometer (LAS) in the Heihe River Basin, China, in 2008 and 2009. We also determined the source areas of the EC and LAS measurements with a footprint model for each site, and discussed the differences between the sensible heat fluxes measured by EC and LAS. The results show that the main EC source areas were within a radius of 250 m at all sites. The main source area for the LAS (with a path length of 2390 m) stretched along a path line approximately 2000 m long and 700 m wide. The surface characteristics in the source areas changed according to season and site, and there were characteristic seasonal variations in the energy and water vapor fluxes at all sites. The sensible heat flux was the main term of the energy budget during the dormant season. During the growing season, however, the latent heat flux dominated the energy budget, and an obvious "oasis effect" was observed at YK. The evapotranspiration (ET) at YK was larger than those at the other two sites. The monthly ET reached its peak in July at YK and in June at GT in both 2008 and 2009, while it reached its peak in August at AR in 2008 and in June in 2009. The sensible heat fluxes measured by LAS at AR were larger than those measured by EC at the same site. This difference seems to be caused by the energy imbalance of EC, the heterogeneity of the underlying surfaces, and the difference between the source areas of the LAS and EC measurements.
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Notice on Discussion StatusCitation: Liu, S., Xu, Z., Wang, W., Bai, J., Jia, Z., Zhu, M., and Wang, J.: Measurements of energy and water vapor fluxes over different surfaces in the Heihe River Basin, China, Hydrol. Earth Syst. Sci. Discuss., 7, 8741-8780, doi:10.5194/hessd-7-8741-2010, 2010. Bibtex EndNote Reference Manager XML
