| Three-year Variations of Water, Energy and CO_2 Fluxes of Cropland and Degraded Grassland Surfaces in a Semi-arid Area of Northeastern China |
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| 作者姓名： | LIU Huizhi TU Gang FU Congbin SHI Liqing |
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| 作者单位： | State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry，Institute of Atmospheric Physics，Chinese Academy of Sciences，Key Laboratory of Regional Climate-Environment Research for Temperate East Asia，Institute of Atmospheric Physics，Chinese Academy of Sciences |
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| 基金项目： | 国家重点基础研究发展计划(973计划) |
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| 摘 要： | Based on 3 years （2003-05） of the eddy covariance （EC） observations on degraded grassland and cropland surfaces in a semi-arid area of Tongyu （44°25′N, 122°52′E, 184 m a.s.1.）, Northeast China, seasonal and annual variations of water, energy and CO2 fluxes have been investigated. The soil moisture in the thin soil layer （at 0.05, 0.10 and 0.20 m） clearly indicates the pronounced annual wet-dry cycle; the annual cycle is divided into the wet （growing season） and dry seasons （non-growing season）. During the growing season （from May to September）, the sensible and latent heat fluxes showed a linear dependence on the global solar radiation. However, in the non-growing season, the latent heat flux was always less than 50 W m^-2, while the available energy was dissipated as sensible, rather than latent heat flux. During the growing season in 2003-05, the daily average sensible and latent heat fluxes were larger on the cropland surface than on the degraded grassland surface. The cropland ecosystem absorbed more CO2 than the degraded grassland ecosystem in the growing season in 2003-05. The total evapotranspiration on the cropland was more than the total precipitation, while the total evapotranspiration on the degraded grassland was almost the same as the total annual precipitation in the growing season. The soil moisture had a good correlation with the rainfall in the growing season. Precipitation in the growing season is an important factor on the water and carbon budget in the semi-arid area.
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| 关 键 词： | 雨水 涡流 协方差 季风 |
Three-year Variations of Water, Energy and CO$_2$ Fluxes of Cropland and Degraded Grassland Surfaces in a Semi-arid Area of Northeastern China |
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| LIU Huizhi,TU Gang,FU Congbin,SHI Liqing.Three-year Variations of Water, Energy and CO_2 Fluxes of Cropland and Degraded Grassland Surfaces in a Semi-arid Area of Northeastern China[J].Advances in Atmospheric Sciences,2008,25(6):1009-1020. |
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| Authors: | LIU Huizhi TU Gang FU Congbin and SHI Liqing |
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| Institution: | [1]State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029 [2]Key Laboratory of Regional Climate-Environment Research for Temperate East Asia, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029 |
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| Abstract: | Based on 3 years (2003--05) of the eddy covariance (EC) observations on degraded grassland
and cropland surfaces in a semi-arid area of Tongyu (44 25'N, 122 52'E, 184 m a.s.l.),
Northeast China, seasonal and annual variations of water, energy and CO2 fluxes have been investigated.
The soil moisture in the thin soil layer (at 0.05, 0.10 and 0.20 m) clearly indicates the pronounced annual
wet-dry cycle; the annual cycle is divided into the wet (growing season) and dry seasons (non-growing
season). During the growing season (from May to September), the sensible and latent heat fluxes showed a
linear dependence on the global solar radiation. However, in the non-growing season, the latent heat flux
was always less than 50 W m-2, while the available energy was dissipated as sensible, rather than
latent heat flux. During the growing season in 2003--05, the daily average sensible and latent heat fluxes were
larger on the cropland surface than on the degraded grassland surface. The cropland ecosystem absorbed more CO2
than the degraded grassland ecosystem in the growing season in 2003--05. The total evapotranspiration on the
cropland was more than the total precipitation, while the total evapotranspiration on the degraded grassland
was almost the same as the total annual precipitation in the growing season. The soil moisture had a good
correlation with the rainfall in the growing season. Precipitation in the growing season is an important
factor on the water and carbon budget in the semi-arid area. |
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| Keywords: | water energy and flux semi-arid area eddy covariance seasonal and annual variation |
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