采用耦合湖泊模型的WRF_CLM模式模拟山谷盆地中洱海的湖泊效应,并利用陆面(农田)和湖面的站点观测资料对模式进行了验证和校验。基于数值模式的模拟结果,分析了季风和非季风期间,洱海存在与否对山谷盆地局地环流及大气边界层结构的影响。发现非季风期湖泊对局地环流及大气边界层影响显著。相对于陆地,湖泊白天湍流通量输送少,湍流发展弱,大气边界层高度低。如果湖泊不存在,白天苍山山谷风只能上升至约200 m的高度,没有明显的山谷风环流形成;夜间则山风较强,两侧山风共同作用在山谷,环流高度约600 m。季风期,受降水天气影响,局地环流发展不充分。白天湖面辐散以及夜间湖泊南部的气旋式环流弱,湖泊作用没有非季风期明显。云的形成导致边界层高度较低。夜间,湖泊增强释放潜热、感热作用明显;此时湍流发展,夜间边界层反而比白天高。
The lake effect of Erhai in the complex valley and basin area was simulated using the WRF_CLM model which includes a lake module.The observational stations over cropland and lake were used to verify the model results.We have analyzed the lake effect of Erhai on local circulation and boundary layer structure during monsoon and non-monsoon periods with the model.The experiments with or without Erhai lake during non-monsoon period show that Erhai lake has a great impact on the local circulation and boundary layer structure.Compared with land surface,lake surface transfers less turbulent flux,and the development of turbulence is weaker in the daytime,which leads to lower boundary height.Valley breeze only reaches up to200 m without the lake breeze.There is no mountain-valley breeze circulation in the nolake experiment.In the evening,the strong synergism of mountain breeze of Cangshan and Yu'anshan makes the circulation height reaches up to 600 m.Affected by precipitation system,local circulation can't develop well during the monsoon period.Divergence flow during the daytime and cyclonic circulation during the nighttime are weaker in monsoon periods than that in non-monsoon periods.In the daytime,there are clouds formed,and the boundary layer height is low.In the evening,the difference of water vapor pressure between lake surface and air is large,which results to the great value of latent heat flux.At the same time,turbulance developes,and boundary layer height even gets higher than that in the daytime.