夏季安徽槽前形势下龙卷和非龙卷型强对流天气的环境条件对比研究
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摘要
利用NCEP再分析资料,对安徽省夏季高空槽前形势下两类强对流天气各5次个例的环流特征、热力和动力条件进行了对比分析。结果表明:以大风、短时强降水天气为主的非龙卷类表现为高空的低槽比较深厚,而龙卷的产生多是由于较浅的短波槽引起的,并且低层有西南急流存在,导致较强的垂直风切变。通过比较热力和动力物理量平均场的分布特征发现:在槽前形势下水汽条件都比较好,夏季整层大气可降水量平均在55 mm以上,但出现龙卷时中低层的垂直风切变非常强,龙卷类0～1 km垂直风切变大约是非龙卷类的3倍。由于存在较强的垂直风切变,龙卷类低层的风暴相对螺旋度也强于非龙卷类。从动力和热力条件综合来看,出现龙卷时的对流有效位能并不是很大,但能量螺旋度很大,即风暴相对螺旋度上差异更加明显。因此在预报槽前类龙卷天气时,应重点关注环境风场的垂直切变和风暴相对螺旋度。
Based on NCEP(1°×1°) reanalysis data,the large-sale circulation features as well as thermal and dynamic conditions for two types(5 cases for each type) of severe convective weathers under ahead of trough pattern during summer in Anhui Province are analyzed.The results show that:the nontornadic type mainly causes strong wind and short-time heavy rainfall which is characterized by deep upper trough. However,the tornado is usually triggered by short wave trough with the low-level jet which causes strong vertical wind shear.By comparing the composite thermal and dynamic parameters,it is demonstrated that the moisture condition is good for both types of severe convective weathers and the average precipitable water during summer is above 55 mm.However,the vertical wind shear at middle-to-low levels is very strong when tornado occurs and the 0—1 km vertical wind shear is about 3 times higher than that of nontornadic type.Because of larger vertical wind shear,the storm relative helicity(SRH) of tornadic type is stronger than that of nontornadic type.According to the thermal and dynamic conditions,the CAPE of tornadic type is not very large while the energy helicity is large and significant differences are found in storm relative helicity.Therefore,more attention should be paid to the vertical wind shear and SRH in forecasting the tornado under ahead of trough pattern.
Based on NCEP(1°×1°) reanalysis data,the large-sale circulation features as well as thermal and dynamic conditions for two types(5 cases for each type) of severe convective weathers under ahead of trough pattern during summer in Anhui Province are analyzed.The results show that:the nontornadic type mainly causes strong wind and short-time heavy rainfall which is characterized by deep upper trough. However,the tornado is usually triggered by short wave trough with the low-level jet which causes strong vertical wind shear.By comparing the composite thermal and dynamic parameters,it is demonstrated that the moisture condition is good for both types of severe convective weathers and the average precipitable water during summer is above 55 mm.However,the vertical wind shear at middle-to-low levels is very strong when tornado occurs and the 0—1 km vertical wind shear is about 3 times higher than that of nontornadic type.Because of larger vertical wind shear,the storm relative helicity(SRH) of tornadic type is stronger than that of nontornadic type.According to the thermal and dynamic conditions,the CAPE of tornadic type is not very large while the energy helicity is large and significant differences are found in storm relative helicity.Therefore,more attention should be paid to the vertical wind shear and SRH in forecasting the tornado under ahead of trough pattern.
引文
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[3]曹志强,方宗义,方翔.2007年7月皖苏北部龙卷风初步分析??[J].气象,2008,34(7):15-19.
[4]吴海英,沈树勤,蒋义芳.龙卷诱发原因的实例分析[J].气象科学,2009,29(3):335-341.
[5]郑媛媛,朱红芳,方翔,等.强龙卷超级单体风暴特征分析与预警研究[J].高原气象,2009,28(3):617-625.
[6]郝莹,姚叶青,陈焱.基于对流参数的雷暴潜势预报研究[J].气象,2007,33(1):51-56.
[7]梁爱民,张庆红,申红喜,等.北京地区雷暴大风预报研究[J].气象,2006,32(11):73-80.
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[9]赵培娟,吴蓁,郑世林,等.河南省强对流天气诊断分析预报系统[J].气象,2010,36(2):33-38.
[10]郑永光,张小玲,周庆亮,等.强对流天气短时临近预报业务技术进展与挑战[J].气象,2010,36(7):33-42.
[11]郑媛媛,姚晨,郝莹,等.不同类型大尺度环流背景下强对流天气的短时临近预报预警研究[J].气象,2011,37(7):795- 801.
[12]雷蕾,孙继松,魏东.利用探空资料判别北京地区夏季强对流的天气类别[J].气象,2011,37(2):136-141.
[13]俞小鼎,姚秀萍,熊廷南,等.多普勒天气雷达原理与业务应用[M].北京:气象出版社,2005:90-169.
[14]Thompson R L.Edwards R.Hart J A.et al.Close proximity soundings within supercell environments obtained from the Rapid Update CycIe[J].Wea Forecasting,2003,18(6),1243- 1261.
[15]Davies-Jones J M.Hourly helicity,instability,and EHI in forecasting supercell tornadoes[M].Preprints,17th Conf on Severe Local Storms,St.Louis,MO,Amer Meteor Soc,1993,107-111.
[16]王丽荣,胡志群,匡顺四.应用雷达产品计算风暴相对螺旋度[J].气象,2006,32(4):45-51.
[17]Colquboun J R,Riley P R.Relationship between tornado and various wind and thermodynamic variable[J].Wea Forecasting, 1996,11(3):360-371.
[18]刘娟,朱君鉴,魏德斌,等.070703超级单体龙卷的多普勒雷达典型特征[J].气象,2009,35(10):32-39.
[2]姚叶青,俞小鼎,郝莹,等.两次强龙卷过程的环境背景场和多普勒雷达资料的对比分析[J].热带气象学报,2007,23 (5):483-490.
[3]曹志强,方宗义,方翔.2007年7月皖苏北部龙卷风初步分析??[J].气象,2008,34(7):15-19.
[4]吴海英,沈树勤,蒋义芳.龙卷诱发原因的实例分析[J].气象科学,2009,29(3):335-341.
[5]郑媛媛,朱红芳,方翔,等.强龙卷超级单体风暴特征分析与预警研究[J].高原气象,2009,28(3):617-625.
[6]郝莹,姚叶青,陈焱.基于对流参数的雷暴潜势预报研究[J].气象,2007,33(1):51-56.
[7]梁爱民,张庆红,申红喜,等.北京地区雷暴大风预报研究[J].气象,2006,32(11):73-80.
[8]陈艳,寿绍文,宿海良.CAPE等环境参数在华北罕见秋季大暴雨中的应用[J].气象,2005,31(10):56-61.
[9]赵培娟,吴蓁,郑世林,等.河南省强对流天气诊断分析预报系统[J].气象,2010,36(2):33-38.
[10]郑永光,张小玲,周庆亮,等.强对流天气短时临近预报业务技术进展与挑战[J].气象,2010,36(7):33-42.
[11]郑媛媛,姚晨,郝莹,等.不同类型大尺度环流背景下强对流天气的短时临近预报预警研究[J].气象,2011,37(7):795- 801.
[12]雷蕾,孙继松,魏东.利用探空资料判别北京地区夏季强对流的天气类别[J].气象,2011,37(2):136-141.
[13]俞小鼎,姚秀萍,熊廷南,等.多普勒天气雷达原理与业务应用[M].北京:气象出版社,2005:90-169.
[14]Thompson R L.Edwards R.Hart J A.et al.Close proximity soundings within supercell environments obtained from the Rapid Update CycIe[J].Wea Forecasting,2003,18(6),1243- 1261.
[15]Davies-Jones J M.Hourly helicity,instability,and EHI in forecasting supercell tornadoes[M].Preprints,17th Conf on Severe Local Storms,St.Louis,MO,Amer Meteor Soc,1993,107-111.
[16]王丽荣,胡志群,匡顺四.应用雷达产品计算风暴相对螺旋度[J].气象,2006,32(4):45-51.
[17]Colquboun J R,Riley P R.Relationship between tornado and various wind and thermodynamic variable[J].Wea Forecasting, 1996,11(3):360-371.
[18]刘娟,朱君鉴,魏德斌,等.070703超级单体龙卷的多普勒雷达典型特征[J].气象,2009,35(10):32-39.
目录
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