大连地区雷暴大风的气候和天气学特征

摘要

基于1999—2013年大连地区的雷暴大风、雷暴和冰雹等观测资料,对大连地区雷暴大风天气的气候和天气学特征进行了分析.结果表明:1999—2013年大连地区雷暴大风天气具有较强的地域特点,夜间雷暴大风天气的发生频率明显高于白天,海岛站雷暴大风出现次数明显多于陆地站;雷暴大风天气主要集中出现在夏季,10月雷暴大风发生也较多.统计表明,大连地区雷暴大风天气通常发生在空间尺度和时间尺度均相对较大的雷暴群中,单体雷暴出现雷暴大风的概率极低,且大都伴有降水,但雷暴大风与暴雨或冰雹相伴出现的概率较低.大连地区的雷暴大风天气是由多种有利的高低空系统配置及高低空急流和中高空干空气的共同作用产生的,其中高空急流和中高空干空气是制约雷暴大风产生的重要因素,高空急流有时制约雷暴大风的产生方位和分布形态,大连地区雷暴大风通常位于高空急流轴下方及其附近区域;中高空干空气具有3个作用:一是增强大气不稳定度;二是在干湿区的交界处形成较强的露点锋,有时具有雷暴的触发作用;三是与其他天气系统叠加时具有增强上升运动的作用.%Based on the observation data of thunderstorm gale,thunderstorm,hail and other weather phenomena in the region of Dalian region from 1999 to 2013 , the climatic and synoptic characteristics of thunderstorm gale in Dalian were analyzed. The results reveal that occurrence regularity of thunderstorm gale in Dalian has a strong re-gional characteristic. The occurrence frequency at night is significantly higher than that at daytime. The number of thunderstorm gales happened on the island stations is significantly greater than that on the land stations. Thunder-storm gales mainly occur in summer. In addition,October is also the time when thunderstorm gales happened fre-quently. Statistics analyses show that the thunderstorm gales often occur in the thunderstorm groups which have a large spatial scale and time scale in Dalian region,and the probability that a single thunderstorm cell causes thun-derstorm gales is very low. Mostly,the occurrence of thunderstorm gales accompanies with rainfall,while the oc-currence of thunderstorm gale rainstorm or hail simultaneously is rare. The thunderstorm gales in Dalian region are usually formed by the combination of many favorable configurations of upper and lower altitude systems,jet stream at upper and lower level and dry air at middle and upper altitude. The most important factors that control the gener-ation of thunderstorm gale are jet streams at the upper level and dry air at the middle and upper altitude. The jet stream at an upper level sometimes controls the location and the distributing pattern of the thunderstorm gale. Thunderstorm gales in Dalian region usually located at the areas near and down the axis of the upper level jet stream. There are three functions for dry air at the middle and upper altitude,i. e. enhancing the atmospheric insta-bility,forming a very strong dew-point front at the junction of dry and wet areas and sometimes triggering thunder-storms,and enhancing the ascending motion when it superposes with other weather systems.