2003年4月江西一次强对流天气过程的诊断分析

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钱传海, 张金艳, 应冬梅, 林建. 2003年4月江西一次强对流天气过程的诊断分析[J]. 应用气象学报, 2007, 18(4): 460-467. 复制到剪切板

Qian Chuanhai, Zhang Jinyan, Ying Dongmei, Lin Jian. A Severe Convection Weather of Jiangxi in April 2003[J]. Journal of Applied Meteorological Science, 2007, 18(4): 460-467 复制到剪切板

2003年4月江西一次强对流天气过程的诊断分析

钱传海¹, 张金艳¹, 应冬梅², 林建¹

1. 国家气象中心, 北京 100081;
2. 江西省气象局环境预报中心, 南昌 330046

2006-06-16 收到, 2007-05-15 收到修改稿.

资助项目: 国家自然科学基金项目 (40205008) 和国家气象中心课题 (LD-05, ZK2002A-02) 共同资助

摘要: 利用NCEP/NCAR再分析资料、TBB资料、探空资料及多普勒雷达资料等对2003年4月12日发生在江西以及福建北部的强对流天气过程进行了诊断分析。结果表明:此次强对流天气过程是在高空槽和低层低涡切变线的有利形势下产生的, 这种下层暖湿、上层干冷的对流不稳定层结非常有利于强对流天气的产生; 强对流天气发生发展伴有多个中尺度对流云团东移南压的演变过程; 多普勒雷达资料分析表明, 冰雹发生时可观测到79 dBz的反射率因子极值并伴有弓状回波; 对流有效位能积累、释放随时间的演变过程, 对于此次强对流天气过程有很好的指示意义; 强对流天气发生前高层的干冷空气倾斜状向下侵入到对流层中低层附近, 对此次强对流天气的发生发展起了非常重要的作用; 能量锋区及锋区上强的垂直涡柱为该次强对流天气过程提供了有利的热力和动力学条件。

关键词: 强对流天气对流有效位能干侵入

A Severe Convection Weather of Jiangxi in April 2003

Qian Chuanhai¹, Zhang Jinyan¹, Ying Dongmei², Lin Jian¹

1. National Meteorological Center, Beijing 100081;
2. Environmental Forecast Center, Jiangxi Provincial Meteorological Bureau, Nanchang 330046

Abstract: Convection weather is one of the most severely disastrous weather phenomena in China, with features of small spacial scale, short life span, sudden emergence and great damaging force.It is always very difficult to make an accurate analysis and forecast for severe convection weather in the daily operational work.With the application of Doppler radar and the development of numerical weather prediction technology, the know ledge about the severe convection weather and the related mechanisms is also improved in recent years.Effective ways have been developed in some countries to be applied in the analysis and forecast for severe weather.Examples can be found in U S A, where parameter estimation, graphics identification and statistical characteristics based on climate have been put into operational use for forecast of hailstones and tornadoes, and proved to be useful in improving the accuracy.Much improvement is also made in China Meteorological Administration in recent years in severe weather observation, many new instruments, such as radars, automatic weather stations, lightening detection and GPS/MET vapor detection instruments etc have been gradually put into operational use.These new data definitely provide forecasters and researchers good opportunities to study the severe convection weather and improve the forecast accuracy.Using NCEP/NCAR daily meteorological reanalysis data, sounding data, TBB and Doppler radar images, a typical convection induced severe weather process occurred on April 12—13, 2003 in Jiangxi and northern Fujian is diagnosed and analyzed, the result shows that this severe convection weather takes place under favorable conditions of upper trough coupling with a low-level vortex and shear environments. Lower level southwesterly jet contributes as a vapor transportation passage.Dry and cold airs of upper level overlapping upon wet and warm airs in low er level create a convectively unstable layer.Under this condition, convective weather could be easily initiated and high instability energy releases with suitable triggering mechanism. Several mesoscale convective clouds involve in the development of the severe weather, and deep convection mostly concentrates on the frontal parts of the clouds where TBB isolines converging with high gradient.Also the Doppler radar images show that the maximum reflection up to 79 dBz is reported during hail-fall, and bow echo could be observed.Convective available potential energy (CAPE) is a meaningful sign in the process of convection event.Before the severe weather, CAPE grow s gradually and accumulates.The severe weather initiates soon after the CAPE reaches its peak values, then with CAPE's releasing and becoming weak rapidly, severe weather downgrades.Dry air intrusion to mid-level from upper level plays an important role in the development of convection.Energy-front zone and strong vertical vorticity-pole provides thermodynamic and dynamic conditions for this severe convection weather.

Key words: severe convection weather CAPE dry intrusion

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图 1. 2003年4月12日江西和福建北部出现强对流天气的站点 Fig 1. Severe convection weather stations in Jiangxi and northern Fujian on April 12, 2003


图 3. 2003年4月12日12:00—17:00 TBB分布图 (单位: ℃; 图中化给出TBB值低于-40 ℃的等值线图; 其中A, B, C, D分别为对流云团编号) Fig 3. TBB evolution during 12:00—17:00 on April 12, 2003 (unit:℃; only for TBB value lower than-40 ℃; A, B, C, D denote the numbering of cloud clusters)


图 4. 对流有效位能水平分布及其随时间演变 (单位: J/kg) (a)2003年4月12日08:00水平分布图, (b)2003年4月10—14日江西弋阳E_CAP时间演变图 Fig 4. Convective available potential energy distribution and its time series (unit : J/kg) (a)E_CAP distribution at 08:00 on April 12, 2003, (b)E_CAP time series during April 10—14 at Yiyang, Jiangxi


图 5. 2003年4月11—13日南昌站点垂直速度高度-时间剖面图 (单位: Pa/s) Fig 5. Height-time cross section of vertical wind at Nanchang during April 11—13, 2003 (unit : Pa/s)


图 6. 2003年4月12日14:00过南昌站点相对湿度 (实线, 单位: %)、气流场 (矢量箭头, 由南北风速与垂直速度合成) 沿115.9°E垂直剖面图 Fig 6. Cross section of relative humidity (solid line, unit: %), airflow (vector, combination of v and ω) along 115.9°E at 14:00 on April 12, 2003


图 7. 2003年4月12日14:00沿117°E θ_se(实线, 单位: K) 和涡度场 (阴影区为正涡度区, 虚线为负涡度, 单位: 10^-5s^-1) 垂直剖面图 Fig 7. Cross section of θ_se(solid lines, unit : K) and vorticity (shaded area for positive vorticity, dashed line for negative, unit : 10^-5s^-1) along 117°E at 14:00 on April 12, 2003


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