太行山东麓焚风天气的统计特征和机理分析Ⅰ:统计特征

利用2007-2008年京津冀区自动站资料,根据小时变温,对太行山东麓焚风天气进行了详细的统计和分析。结果表明,焚风具有明显的季节变化和日变化,其分布特征在夜间表现明显,强焚风一般出现在太行山东侧50km内,而弱焚风则可到达太行山以东100km范围内;太行山北段的东南侧和南段的东侧呈现出两个焚风中心,而中段附近焚风出现的相对较少;焚风出现的位置与风向的关系密切,西北风造成的焚风主要出现在太行山北段东侧,偏西风主要影响太行山南段,而西南风主要影响中段;焚风强度与风速大小有一定的对应关系,具有明显的阵性特征;在红外云图中焚风常表现为一条明显的暗带;太行山东麓焚风造成的加热区可向东或东南方向移动,影响河北平原。

Feature and Mechanism of the Foehn Weather on East Slope Taihang MountainsⅠ：Statistic Feature

Using the observation of two-element AWSs in Hebei Province,multi-element AWSs in Beijing and Tianjin,the foehn occurred on east slope of Taihang Mountains is detail analyzed according to hourly temperature variation.The results show that: The foehn has obvious seasonal and diurnal variations;The distribution features is clear at night,strong foehn usually occurs within 50 km on east side of Taihang Mountains,but weak foehn can reach up Taihang Mountains to the east 100 km area.There are two foehn centers in northern and southern parts of Taihang Mountains;the foehn is closely related with wind direction,foehn caused northwest wind is mainly in the northern parts of Taihang Mountains,west ward wind mainly affect foehn in the southern parts of Taihang Mountains,while the southwest wind mainly affects foehn in the middle part of Taihang Mountains;Foehn strength is somewhat corresponding to wind speed;it has obvious gustiness,and often appears a clear dark band in infrared cloud image.The heating zone caused by foehn may move to east or southeast which cause rapid rising temperature in Hebei Plain.