【摘要】 利用 1 995～ 1 998年中日季风实验期间拉萨等 4个高原自动天气站观测资料 ,结合 1 995 /1 996年 NCEP/NCAR逐日资料 ,研究了青藏高原气象要素场低频位相结构特征及其与我国夏季不同区域降水的关系。发现夏季低频感热和低频潜热具有同位相 30～ 5 0 d振荡 ,当低频感热增强 ,则同期高原降水量减少 ;反之 ,则高原降水量增加。低频纬向风传播分析发现 1 995 /1 996年冬季高原是低频振荡的汇 ,2 0 0 h Pa低频纬向风在冬季与低频地面气压有显著的负相关 ,与地面低频感热的位相差为 3π/8,时间滞后约为 1周。进一步分析表明 :2 0 0 h Pa纬向风与夏季拉萨等地降水具有正相关 ,而与华北等地的降水具有负相关 ,且均能通过 α=0 .0 5信度检验。更多还原

【Abstract】 Based on 1995~1998 datasets at 4 AWS over the Tibetan plateau during the experiment of Sino Japan cooperation on Asian Monsoon and 1995~1996 daily NCEP/NCAR reanalysis data,study is performed of the features of LFO phase structure with its relation to summer regional rainfall.Results show that the 30~50 d LFO of sensible/latent heat flux has the same phase,with the exhanced phase corresponding to less plateau rainfall and v.v..The propagation of 200 hPa LFO zonal wind reveals that the Plateau is a sink region for LFO in winter of 1995~1996.Further evidences show that 200 hPa LFO zonal wind,which is regatively correlated with LFO station pressure and lags about one week to LFO surface sensible heat flux with a phase difference of 3π/8 ,is positively (negatively) correlated to summer rainfall in Lhasa (north China).更多还原