1998年夏季青藏高原多时间尺度低频降水的活动和传播特征

研究表明，准４５ｄ、准２３ｄ和准１４ｄ等３类低和水的频率愈低，低和水愈趋向于从高原东侧和南侧向高原传播，反之，频率愈高，低频降水愈趋向于由高原向高原东侧和南侧传播。低频降水的传播路径倾向于与其上空１５０ｈＰａ低辐散带的传播中径相一致，但强度则不完全一致。高原中南就低频降水强度远大于高原北部，且与其周围平原和海洋地区的低频降水具有相对独立性。

MULTITIME SCALE LOW FREQUENCY PRECIPITATION ACTIVITIES AND PROPAGATION FEATURES OVER THE TIBETAN PLATEAU AND ITS VICINITIES IN THE SUMMER OF 1998

It is found that there exist quasi 45 d,quasi 23 d and quasi 14 d low frequency precipitation over the plateau and that the lower of the frequency,the more likely of their propagation from south and east side of the plateau to the plateau itself,and v.v.The low frequency rainfall propagation trends to follow the path of propagation of the overhead low frequency divergence at 150 hPa.The intensity of low frequency rainfall,which is somewhat different from that of low frequency divergence,is far more strong over center and south of the plateau than over north of the plateau and is relatively independent of the plateau's vicinities.