选取2004-2014年江西省11个ADTD雷电探测定位组网系统所得云地闪探测数据、省内多普勒雷达、探空和自动站资料,并结合重要天气报,将此11年的强对流天气分成短时强降水、有短时强降水伴随的雷雹大风和冰雹(以下简称风雹)和无短时强降水伴随的风雹这三种主要类型,分析它们发生前后的地闪活动特征及其与雷达回波的关系,结果发现,(1)江西省短时强降水、雷暴大风和冰雹分别主要发生在5-8、7-8月和3月;仅发生短时强降水时的站次远多于发生风雹天气时;除早春和盛夏无短时强降水伴随的雷暴大风发生站次较多外,风雹天气常与短时强降水相伴发生.(2)仅有短时强降水天气发生时,其站点地理位置越偏北、小时雨量越大,对应的地闪活动就越剧烈.不同小时雨量对应的地闪数存在较明显的季节性差异,表现为3、4月地闪数以小时雨量为50～55 mm时最多;5-7月地闪数随着小时雨量增大总体呈增多趋势,尤以小时雨量为55～60 mm时最多;8-9月则以小时雨量为40～45 mm时最多.(3)就无短时强降水伴随的风雹天气而言,在3-5月雷暴大风和冰雹发生前30 min内的地闪数差异不大,但平均电流强度后者大于前者;在6-9月雷暴大风发生前30min内的地闪数则为冰雹发生前的2～4倍,平均电流强度前者大于后者;该类风雹发生前的地闪数多于仅有短时强降水发生前,正地闪的平均电流强度前者也略强.(4)有短时强降水伴随的风雹发生前的平均正地闪数以8月为最多,而负地闪数则在6月最多;冰雹发生前1h内的地闪数随季节变化不大,而雷暴大风发生前的地闪数存在季节差异,夏季多于春季;另外冰雹的地闪数与冰雹直径存在较好的正相关性.(5)3-8月,有短时强降水伴随的风雹地闪数远多于无短时强降水伴随时;其平均电流强度前者大于后者;该类风雹天气发生前,地闪平均电流强度随季节呈先增大后减小的趋势,而无短时强降水伴随的风雹天气则无此特点.(6)强对流天气发生前,较强回波出现前的负地闪活动远比正地闪活跃,但其电流强度弱于正地闪;45dBz以上回波伸展高度越高,伴随的地闪数也越多,但其平均电流强度变化不明显.%Based on the data from cloud-to-ground (CG) lightning detection network with 11 ADTD equipment,doppler radar,sounding,AWS data and important weather reports in Jiangxi Province during 2004 -2014,severe convective weather events in these years are divided into three types:the short-time heavy rainfall,the thunderstorm gale or hail with and without short-time heavy rainfall.The characteristics of the CG flashes and their relations to radar echoes are analyzed statistically.The results show that:(1) The short-time heavy rainfall,thunderstorm gale and hail in J iangxi occur mainly from May to August,July to August and March respectively.The stations with short-time heavy rainfall are much more than those with thunderstorm gale or hail.The thunderstorm gale or hail weather accompanied by short-time heavy rainfall often occurs in most seasons in addition to early spring and middle summer.(2) The more short-time heavy rainfall intensity is the more northern its position,and the more severe the CG flashes are.There are obvious seasonal differences of CG flash totals with different hourly rainfall:In March and April,the CG flashes are most evident with hourly rainfall of 50-55 mm,while in May,June and July,the CG flashes increase with hourly rainfall,reaching the top with hourly rainfall of 55-60 mm.In August and September,the most evident is the events with the hourly rainfall of 40-45 mm.(3) From March to May,CG flashes seen 30 min before hail without short-time heavy rainfall have no significant differences compared with those of thunderstorm gale,yet the average intensity of thunderstorm gale is higher than that of hail weather.From June to September,CG flashes in thunderstorm gales are 2-4 times more than that of hail,the average intensity of the flashes is higher than the former,and the intensity of +CGs is also slightly more intense.(4) The +CGs and-CGs with short-time heavy rainfall occurrence are separately in August and June.For the total CGs one hour before the severe weather happens,the seasonal change of that with hail is not evident,but it turns contrary to thunderstorm gales,more evident in summer than in spring.Also,there is a positive correlation between the hail CG flash totals and hail diameters.(5) From March to August,the CG flashes of thunderstorm gale or hail accompanied with short-time heavy rainfall are much higher than that without short-time heavy rainfall,while the average intensity of the former is much higher than the latter.(6) Before the severe convections take place,the negative CG flashes frequency is more evident than the positive one,but its intensity is lower than the latter.The higher the echo of reflectivity above 45 dBz extends,the more the CG flash totals are,but the average intensity change is not obvious.
展开▼
