利用变分法计算西北典型干旱区地表通量的研究

利用2000年5～6月在敦煌进行的陆面过程野外观测试验加强期的观测资料,采用变分法计算了西北干旱区荒漠戈壁的地表感热通量和潜热通量,并与Bowen比能量平衡方法(简称BREB法)的结果进行了对比.结果表明:变分法由于同时应用了地表能量平衡方程和相似性廓线方程,充分利用了边界层观测资料的信息,避免了BREB法中出现在Bowen比接近于-1时产生的计算不稳定和虚假的峰值,使计算的通量结果更趋合理和稳定.同时也计算了动量和感热的总体输送系数,与已有结果比较表明也具有合理性.

A Study of Computing the Surface Flux in the Typical Arid Region of Northwest China by a Variational Method

By using the data observed during the intensive observation period of the Dunhuang Land-Surface Process Field Experiment (DLSPFE) from May through June in 2000, a variational method is applied to compute surface fluxes of sensible and latent heat over Gobi in the typical arid region of Northwest China. In comparison with the conventional Bowen ratio energy balance (BREB) method, by making fuller and more complete use of the information provided by the observational data and by the surface energy balance equation and the similarity profile equations, the variational method solves the problem that the BREB method becomes computationally unstable and produces spurious large values when Bowen ratio is in the vicinity of -1. The fluxes and bulk transport coefficients computed by the variational method are more rational and stabler than those of the BREB.