陆面植被类型对华北地区夏季降水影响的数值模拟研究

为了检验陆面植被类型变化对华北地区夏季降水的影响，共做了５组数值试验，结果表明，在华北地区以草原或沙漠代替落叶林后，华北地区夏季降水略有减少，但降水总量变化不大，这主要是由于降水变化的区域分布不一致所致；在华北西北部以沙漠代替草原后，华北地区平均降水有所增加，这主要是由华北北部地区降水增加引起的。上述三个试验中，华北 中部以南地区的降水变化主要由积云对流降水变化引起，以北主要由大尺度降水变化引起。

NUMERICAL SIMULATION STUDY FOR THE EFFECT OF GROUND VEGETATION TYPE ON NORTH CHINA SUMMER PRECIPITATION

We have five numerical experiments to study the effect of vegetation type on North China summer precipitation. The results show,when the deciduous forest over North China is replaced by grasslands or desert, the area mean summer precipitation will be reduced. But it will be increased when replacing the grasslands by desert over northwest part of North China and it is caused by the increasing of the precipitation over northern part of North China. To above mentioned three experiments, the changing of precipitation is mainly caused by the changing of cumulus convective precipitation over southern part of North China, but mainly caused by large scale precipitation changing over northern part of North China. When the deciduous forest is replace by farmland, the summer precipitation over North China will be increased and it is mainly caused by the changing of large scale precipitation. The further analysis of the physical mechanism tells us that the effect of the ground vegetation type on North China summer precipitation like this:first changing the ground vegetation will change the surface roughness and surface albedo,then it will change the variation of the energy exchanging between ground and atmosphere,again then it changes the local circulation.