使用1998年美国NCEP再分析的逐日资料,研究了1998年夏季青藏高原及其邻近地区低频降水的分布和传播特征。结果表明:青藏高原及其邻近地区的低频降水量和时间变化方差对总降水量及其变化方差均具有重要贡献,因此研究高原地区低频降水的分布、发生、发展及其传播特征具有重要意义。高原东侧的低频降水主要由东向西传播,而南侧主要由南向北传播,但很少直接进入高原。高原中南部和东南部可能是高原地区低频降水的发生源地,高空低频散度是影响低频降水发生和传播的重要因子,它的传播方向与低频降水的传播方向基本一致。

Using NCEP reanalysis day-to-day data in 1998,the LFP(low frequency precipitation) distribution and propagation features over Qinghai-Xizang Plateau in the summer of 1998 are investigated.Results show that both LFP and its variance have noticeable contribution to total rainfall and its variance respectively in the target region.So it is practical important to research distribution,occurrence developing and migration of LFP over the highland.LFP to the east(south) of Qinghai-Xizang Plateau marches mainly west ward(north ward),but to the south very few travels into Qinghai-Xizang Plateau.Mid-and southern-and southeast of the highland may be original area of LFP developing over Qinghai-Xizang Plateau.Upper level LF(low frequency) divergence is a significant factor that influences genesis and propagation of LFP.The migration direction of the LF divergence is essential the same as the LFP.