东营市暴雨气候特征

Analysis on Climatic Character of Rainstorm in Dongying,Shandong

利用1971—2004年东营市5个气象站近34年的日降水量资料,采用Petitt方法和合成分析等方法,研究了东营市暴雨的气候特征,及产生这种特征的原因。研究表明:自1970年代以来,东营市暴雨的年代际变化呈现出3个特征时段:1974/1975年发生突变,突变前暴雨年出现站次基本呈上升趋势,突变后明显减少;1990年成为二级变点,之后暴雨年出现站次又有明显增多。1990年代后东营市暴雨明显偏多是在有利的高空环流背景下,北方冷空气和南方暖湿气流频繁交汇的结果。由于东营市特殊的地理位置和地形、地貌影响,导致东营市降水的气候特征与山东省的气候特征变化并不一致,前者呈现出两头高、中间低的倒抛物线形状,而后者却一直呈现出下降趋势。

Based on daily precipitation data of five weather stations of Dongying City from 1971 to 2004, the characteristic of rainstorm change and the produce reasons in this region are studied by using Petitt method and composite analysis. The results show that the inter-decadal variation of Dongying rainstorm has presented 3 characteristic time intervals since the 1970s. The abrupt change of rainstorm happens in 1974/1975. The rainstorm has a trend of escalation before abruption, and it quickly reduced after abruption, 1990 was the second-level change point, afterward the rainstorm frequency obviously increased. Increase in Dongying rainstorm after 1990＇s is attributable to the advantageous upper air circulation background, frequent interaction between the north cold air and south warm and humid air streams. As a result of the Dongying special geographical position, the terrain and landform influence cause the Dongying precipitation＇s dimate characteristics being inconsistent with that of Shandong Province. The former change is counter-parabola shape, but in the whole province it appears to be consistently decreasing tendency.