【摘要】 从物质收支方程出发,推导了一个包含物质存贮、水平平流输送、垂直对流输送以及传统的涡度相关项的地气通量计算方程。平流项本质上是地表非均匀性的结果,不同下垫面的感热和潜热通量也不同,将会产生中尺度环流,使得辐合辐散过程得以维持,从而将体元内的物质输送到体元以外,因此可以通过计算水汽和感热的存贮,间接求出物质的水平平流输送。量纲分析和实际的资料应用都表明,存贮和平流的通量贡献是非常小的。尤其是在均匀下垫面下,方程中的存贮和平流项的通量贡献可以忽略,因此估算地气通量时仅需考虑涡度相关项和Webb修正项即可。而在非均匀下垫面下,在1d以上的时间尺度上,为方便计算,可以忽略存贮和平流的通量贡献;而在小时这样的时间尺度上,从物质能量收支守恒的角度考虑,估算地气通量需要包括存贮和平流的通量贡献。更多还原

【Abstract】 The authors begin with the conservation equation and re-derived the budget equation of a scalar c,which including the storage,the advection,the vertical advection and the traditional eddy covariance term.The advection term is induced by the heterogeneous underlying surface.The heterogeneousness leads to the difference of the sensible heat flux and the latent heat flux and the creation of the mesoscale circulation flow.Thus the convergence or the divergence procedure sustains,and the scalar is brought out of the control volume.Therefore the authors can indirectly estimate the contribution of the advection term by calculating the storage of the sensible heat flux and the latent heat flux.Both the dimensional analysis and the practical application show that the contributions of the storage and the advection are very small compared with the eddy covariance term.Especially under the homogenous underlying surface,they both become negligible,so only the Webb correction should be counted besides the traditional eddy covariance term when estimating the turbulence flux.However,under the heterogeneous surface,when the time scale is larger than one day,the storage and the advection term also can be negligible for simplifying the calculating process;while when the time scale is smaller than one day,the contribution of the storage and the advection should be counted besides the eddy covariance term and the WPL correction from the point of the conservation of the scalars.更多还原