不同地表通量计算方案的比较与改进

利用2006年南京地区边界层外场观测资料对摩擦速度(u*)和摩擦温度(θ*)的几种计算方案进行了比较.u*计算方案的比较结果表明:在不稳定条件下,Pleim方案计算结果同实测值相比,二者在量值及变化趋势上都有较好的一致性;而在稳定条件下,计算结果较差,为此本文给出了一个新的计算方案,结果表明,改进方案有效的提高了u*计算精度,平均相对误差由56%降低到21%.θ*计算方案的比较结果表明:基于动力粗糙度和热力粗糙度相等的Lee方案计算误差较大,而引入阻尼项的Wesely方案计算结果较前者有明显改进.

Comparison and improvement of different calculation schemes on surface turbulent fluxes

Based on the boundary layer field data observed in Nanjing, in 2006, several calculation schemes on the friction speed (u_*) and the friction temperature (θ_*), are compared. The comparison of u_* calculation results show that: in unstable conditions, Pleim scheme results are in agreement with the measured results very well, both in peak value and in trends. In stable conditions, it shows that there is a relatively large deviation in the calculating results. Therefore, a new calculation scheme is provided. The results show that the accuracy of computations is raised by applying the improved scheme, and the average relative error is decreased from 56% to 21%. The comparison of θ_* calculation results show that: there is a relatively large deviation between the calculated results of Lee scheme, which is based on the equality of the momentum roughness and heat roughness, and the measured results. But Wesely scheme results make an improvement over the former, for a resistance term is added in this scheme.