Numerical Simulations on Mesoscale Fluxes Generated by Desert and Oasis Heterogeneous Distributions
沙漠绿洲非均匀分布引起的中尺度通量的数值模拟

In order to study mesoscale water and heat fluxes induced by heterogeneous landscape in GCMs grid scale, the Pielke model has been coupled with a combined land surface processes model which includes a simplified canopy model and a simplified desert soil model. With this copuled model numerical simulations have been carried out on the typical heterogeneous land surface: oasis and desert which is distributed in the HEIFE experiment area. The results indicate that: (1) The mesoscale fluxes of water and heat are comparable to turbulence fluxes. Therefore,it is necessary to parameterize the mesoscale fluxes in large scale numerical model. (2) There is an optimal patch scale and patch number formesocale fluxes,i.e.,when oasis scale is 60 km and patch number is 3 patches, the mesoscale fluxes are the biggest. The mesoscale fluxes can be neglected when the patch number becomes large. (3) The increase of background wind speed decreases the mesoscale fluxes decrease; The roughness experiments indicate that the decrease of thermal difference between oasis and desert makes the mesoscale fluxes decrease.