黄土塬区麦田能量平衡特征

Characteristics of energy balance in winter wheat field on the Loess Tableland

以黄土塬区冬小麦田为研究对象,基于涡度相关数据分析麦田能量平衡的日变化、季节变化和能量分配特征及其主控因子。结果表明,长武塬区麦田全年获得的净辐射(Rn)为2.56×103MJ·m-2·a-1,涡度相关系统的能量闭合度达到0.72。冬小麦生育期内,越冬期和灌浆期麦田主要能量支配项为感热通量(H),最大值出现在6月,为7.09 MJ·m^(-2)·d^(-1);其他生育期和休闲期,主要能量支配项为潜热通量(LE),最大值出现在5月,为10.71 MJ·m^(-2)·d^(-1)。波文比(β)在生育期平均值为0.57,休闲期为0.46。土壤热通量(G)年总量为-15.26 MJ·m-2·a-1,日总量最大值出现在6月,为1.85 MJ·m^(-2)·d^(-1),10月至次年1月为负值,表现土壤释放热量。

In this paper,eddy covariance data from a winter wheat field on the Loess Tableland were used to investigate the temporal variation of energy components,as well as the characteristics of energy partitioning and its main controlling factors. Results showed that the total net radiation(Rn) throughout the year was 2. 56 × 10~3MJ·m^(-2)·a^(-1),and the energy balance closure degree was 0. 72. In the wintering and grain filling periods,the energy components were dominated by upward sensible heat flux(H),with a maximum value of 7. 09 MJ·m^(-2)·d^(-1)occurring in June. However,in other growing stages and the fallow period,the energy components were dominated by upward latent heat flux(LE),with a maximum value of 10. 71 MJ·m^(-2)·d^(-1)occurring in May. The average of Bowen ratio(β) was 0. 57 in growing season and 0. 46 in the fallow period. The annual total amount of soil heat flux(G) was-15. 26 MJ·m^(-2)·a^(-1). The daily total amount of soil heat flux(G) reached a maximum value of1. 85 MJ·m^(-2)·d^(-1)in June,and it was negative from October to the next January,which showed the release of heat from soil.