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Chinese Agricultural Science Bulletin ›› 2007, Vol. 23 ›› Issue (8): 536-536.

Special Issue: 水稻

• 农业工程科学 • Previous Articles     Next Articles

Energy Balance Closure at Rice Paddy Fields in Subtropical Region

Zhu Yongli ,, Wu Jinshui, Hu Jingliang, Tong Chengli, Han Jiangang   

  • Online:2007-08-05 Published:2007-08-05

Abstract: Eddy covariance (EC) method measuring carbon and energy fluxes provides a unique contribution to the study of the environmental, biological and climatological controls of net surface exchange between vegetation and the atmosphere. Independent methods of evaluating the reliability of the eddy covariance measurements at different ecosystem sites are highly desirable. From 2003, EC technique was used in rice paddy fields to measure carbon flux, latent (LE) and sensible (H) heat flux, the net radiation (Rn) and the heat flux (G) into the soil substrate. In the research, the objectives were to assess the accuracy of eddy covariance method, evaluate the energy balance closure and analyze the change trend during the whole year. Energy balance closure was evaluated by statistical methods of ordinary linear regression, energy balance ratio (the ratio of turbulent energy fluxes to available energy, viz. LE and H against Rn less G) and remnant frequency distribution. These methods indicate a general lack of closure during the whole year, with a mean imbalance of 13% or energy balance ratio of 0.87. The imbalance was greater (15%) during from May to Aug than the other period during the year (8%). The results suggest that estimates of the scalar turbulent fluxes of sensible and LE were underestimated and/or that available energy is overestimated.

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