杭州萧山机场雷暴大风的天气——气候学特征研究

The Synoptic and Climatic Characteristic Studies of Thunderstorm Gusts at Hangzhou Xiaoshan Airport

摘要: 依据2001~2022年杭州萧山机场观测站观测资料和2001~2019杭州站探空资料，对杭州萧山机场61次雷暴大风进行统计分析，结果表明：杭州萧山机场大多数雷暴大风具有下击暴流特征，而且冰雹的落区附近也是大风的爆发区之一；雷暴大风日年际分布不均，有明显的年际变化；雷暴大风明显有季节性，主要出现在夏季，其次为春季，在春季中期和夏季的前期及中期发生强雷暴大风的概率最大；雷暴大风具有明显的日变化特征，夏季主要峰值发生在下午13时到傍晚后20时之间，春季峰值时间在半夜前后，即前半夜20时至凌晨02时之间；86.9%的雷暴大风持续时间在0~30 min之间，春季和秋季雷暴大风的持续时间皆小于20 min；73.9%的雷暴大风时雷暴初始的方向位置位于本场西侧(包含偏西、西南和西北方向)和南侧；雷暴大风最大风速的风向主要集中在两个区域，72.1%的风向在220˚~360˚之间，19.7%的方向在0˚~80˚之间；57.4%的雷暴大风最大风速在20~29 m/s之间，39.2％雷暴大风最大风速在17~19 m/s之间。对抬升指数、K指数和CAPE值做了对比分析，结果显示这三个参数对萧山机场雷暴大风的潜势预报有较大的局限性，而对流层中层700~400 hPa之间的干层和对流层中下层(850~500 hPa)温度递减率对本场雷暴大风的潜势预报有较好的指示作用，其阈值分别为：700~400 hPa之间平均温度露点差不小于6℃，或其单层最大温度露点差不小于10℃；850~500 hPa温差值不小于25℃。

Abstract: Based on observational data from the Hangzhou Xiaoshan International Airport observation station from 2001 to 2022 and sounding data from the Hangzhou station from 2001 to 2019, 61 occurrences of thunderstorm gusts at Hangzhou Xiaoshan International Airport were statistically analyzed. The results indicate the following: Most of the thunderstorm gusts at Hangzhou Xiaoshan International Airport exhibit downburst characteristics, and the vicinity of the hail-fall area is often one of the burst zones for strong winds. The annual distribution of thunderstorm gust days is uneven, showing significant interannual variability. Thunderstorm gusts show clear seasonality, occurring primarily in summer, followed by spring. The highest probability of strong thunderstorm gusts occurs during the middle of spring and the early-to-middle parts of summer. Thunderstorm gusts exhibit distinct diurnal variation characteristics. In summer, the main peak occurs between 13:00 and 20:00 (afternoon to early evening), while the spring peak occurs around midnight, specifically between 20:00 and 02:00 (early night to early morning) Beijing Time. 86.9% of the thunderstorm gusts lasted between 0 and 30 minutes, and the duration of spring and autumn thunderstorm gusts were both less than 20 minutes. For 73.9% of the thunderstorm gusts, the initial direction and location of the thunderstorm was situated to the west side (including west, southwest, and northwest directions) and south side of the airport. The wind directions of the maximum wind speed during thunderstorm gusts are primarily concentrated in two regions: 72.1% of the wind directions are between 220˚ and 360˚, and 19.7% are between 0˚ and 80˚. 57.4% of the maximum wind speeds were between 20 and 29 m/s, while 39.2% were between 17 and 19 m/s. A comparative analysis of the Lifted Index (LI), K Index (KI), and Convective Available Potential Energy (CAPE) was performed, revealing that these three parameters have significant limitations for the potential forecasting of thunderstorm gusts at Xiaoshan Airport. In contrast, the dry layer in the mid-troposphere between 700 and 400 hPa and the temperature lapse rate in the lower-to-mid troposphere (850 to 500 hPa) showed better indicator potential for forecasting thunderstorm gusts at this location. Their respective thresholds are: the average temperature-dewpoint depression between 700 and 400 hPa is not less than 6˚C, OR the maximum single-layer temperature-dewpoint depression between 700 and 400 hPa is not less than 10˚C; the temperature difference between 850 and 500 hPa is not less than 25˚C.