一次华南暖季高架雷暴的天气特征

Synoptic Characteristics of a High-level Thunder Storm During the Warm Season of South China

利用常规气象观测资料、风廓线雷达资料和NCEP/NCAR 1°×1°分析资料,对广东暖季一次伴有短时强降水、强闪电和瞬时大风的强高架雷暴过程进行了分析。结果表明:雷暴发生在地面锋线以北200~400 km处,850 h Pa切变线、700 h Pa低空急流和500 h Pa西风槽前西南风动量下传致使低层风速脉动增强等是触发高架对流的有利动力条件。900 h Pa以下存在逆温层,850 h Pa暖平流加强了逆温层以上层结不稳定,垂直运动发生在逆温层以上,最大上升速度中心在700 h Pa及以上层次。水汽分布呈"上干下湿"状态,低层广东中南部存在明显的水汽辐合,水汽主要来源是孟加拉湾。另外,短时大风的出现可能与强降水粒子在较大环境风中的下沉拖曳作用有关。

Using conventional meteorological observations,wind profilers data and the NCEP/NCAR1° × 1° reanalysis,this work studies a high-level thunder storm during the warm season of Guangdong,which was accompanied with intense short-range rain,intense lightning and transient high winds. The results are shown as follows. The thunder storm happened 200 to 400 km north of a surface front,above which a850 hPa shear,700 hPa low-level jet stream and the downward propagation of momentum from a southwesterly ahead of the westerly trough were favorable conditions for the high-level thunder storm. An inversion layer existed below 900 hPa,a warm advection at 850 hPa strengthened the stratification instability above the inversion layer,vertical motion mainly took place above the layer,and the maximum ascending velocity is at700 hPa and above. For the distribution of water vapor,it was dry at the upper levels but wet at the low levels; significant convergence of water vapor,which originated mainly from the Bay of Bengal,occurred at the low levels in the central and southern parts of the province. The occurrence of short-range high winds may be related with the descending and dragging effect of the particulates of the intense rain in relatively strong environmental wind.