一次飑线过程的雷达回波分析与数值模拟

引用本文

慕熙昱, 党人庆, 陈秋萍, 方德贤, 葛文忠. 一次飑线过程的雷达回波分析与数值模拟[J]. 应用气象学报, 2007, 18(1): 42-49. 复制到剪切板

Mu Xiyu, Dang Renqing, Chen Qiuping, Fang Dexian, Ge Wenzhong. Radar Data Analysis and Numerical Simulation of a Squall Line[J]. Journal of Applied Meteorological Science, 2007, 18(1): 42-49 复制到剪切板

一次飑线过程的雷达回波分析与数值模拟

慕熙昱¹, 党人庆¹, 陈秋萍², 方德贤¹, 葛文忠¹

1. 南京大学中尺度灾害性天气教育部重点实验室, 南京 210093;
2. 福建省建阳市气象局, 建阳 354200

2005-11-18 收到, 2006-08-15 收到修改稿.

摘要: 2003年4月12日, 一条飑线袭击了江西、福建、浙江三省, 所到之处出现冰雹、大风等强烈天气, 这次过程强度强, 影响范围大, 三省交界及附近区域有二十多个测站出现冰雹、大风, 冰雹直径有的达3 cm以上, 最大风速达32 m/s。该文利用建阳新一代天气雷达探测到的回波以及中尺度非静力数值模式 (MM5) 对这次过程进行数值模拟, 分析此次强对流过程。结果表明:雷达回波显示出飑线的带状强回波, 线状回波上呈现波型特征; 在数值模拟结果中看到在系统发生的带状区域内有多个中尺度涡旋存在, 在飑线内有中尺度涡旋簇和弓形回波。

关键词: 强对流系统雷达回波弓形回波中层径向辐合中尺度涡旋

Radar Data Analysis and Numerical Simulation of a Squall Line

Mu Xiyu¹, Dang Renqing¹, Chen Qiuping², Fang Dexian¹, Ge Wenzhong¹

1. Key Laboratory of Mesoscale Weather in Nanjing University, Ministry of Education, Nanjing 210093;
2. Jianyang Weather Bureau, Fujian Province, Jianyang 354200

Abstract: A squall line attacks Jiangxi, Zhejiang and Fujian provinces on April, 12 2003. The severe convective system leads to heavy damage, producing wind gust as large as 32 m/s, 30 mm diameter large hails in the affected area. This process is observed by the CINRAD in Jianyang City. The whole process of this convective system, including the initial stage, the developing stage, the mature stage and the dissipating stage, is analyzed. Many convective structures are observed in the process. At the location of the strong updraft, base reflectivity observed by mid-level elevation is stronger than the low-level and the high-level. This structure is called weak echo area. Corresponding to weak echo, there is a positive velocity area within a large negative velocity area in the mid-level. This structure is judged as mesoscale vortex sometimes by WSR-98D PUP. In fact, this phenomenon means the convergence in the target area, which is known as MARC (mid-level radial convergence). Strong line echoes are observed in squall line by radar. It is well known that bow echoes that develop within a squall line are referred to as line echo wave patterns. In order to analyze the interior structure of the convective system, mesoscale numerical model (MM5V3) is used to simulate this process. In the control numerical simulation, reanalysis NCEP data (1°×1°) is used as the initial conditions. Radar observation data and simulation result are used to analyze the structure and the evolvement. Numerical simulation result confirms that the convective system takes place at the meeting of the northeaster and the southwester. There are many convective vortices and super cells within the 400 km system. Bow echoes appear near the vortices. There are obvious cyclones at the forehead of the line echo and divergence at the tail. Weisman indicates that in a mature bow echo cyclonic and anticyclonic vortices develop north and south respectively, in the channel of rear-to-front flow. These results resemble Weisman's study about squall lines in American. In the period from 0758UTC to 0840UTC, there are respective bow echoes in the north and west, seen from the reflectivity PPI. These results confirm that there are segments of mesoscale vortices and bow echoes in squall lines. Jianyang city is to the east of Wuyi Mountain, and there is a bell-mouthed mountain to the west of Jianyang city, so the influence of the topography should be considered. In order to do that, a sensitive numerical simulation is designed. In the sensitive numerical simulation, the altitude of the mountains near Jianyang is factitiously set equal to the ground. The results of the control and sensitive numerical simulation are compared. It shows that the uplifted velocity in 500 hPa level of control simulation is greater than the velocity of sensitive simulation, and the uplifted area accords with the strong reflectivity echo. These results refer that the windward mountain and bell-mouthed mountain can trigger new convective cells or enhance existing ones.

Key words: convective system radar observation bow echoes MARC mesoscale vortex

[1]	Robert H J, William D H. Derechos: Widespread convectively induced windstorms. Wea Foresting, 1987, 2: 32–49.
[2]	http://amsglossary.allenpress.com/glossary/search?p=1&query=derecho.
[3]	http://vortex.weather.brockport.edu/~rochette/meso-presentations/Derechoes.ppt.
[4]	Fujita T T. Manual of Downburst Identification for Project NIMROD. Department of Geophysical Sciences, University of Chicago, Satellite and Mesometeorology Research Paper, 1978, 156, 104.
[5]	Fujita T T, Fernando C. An analysis of three weather-related aircraft accidents. Bull Amer Meteor Soc, 1978, 58, (11): 1164–1181.
[6]	Burgess D W, Bradley F S. Doppler Radar Observations of a Bow Echo Associated with a Longtrack Severe Windstorm. Preprints, 16th Conf on Severe Local Storms, Amer Meteor Soc, 1993: 203–208.
[7]	Przybylinski R W. The bow echo: observations, numerical simulations, and severe weather detection method. Wea Foresting, 1995, 10: 203–218.
[8]	Weisman M L. The genesis of severe, long-lived bow echos. J Atmos Sci, 1993, 50: 645–670. DOI:10.1175/1520-0469(1993)050<0645:TGOSLL>2.0.CO;2
[9]	Kilmowski B A, Przybylinski R W, Schmocker G K, et al. Observation of the Formation and Early Evolution of Bow Echoes. Preprints, 20th Conf on Severe Local Storms, Orlando, FL, Amer Meteor Soc, 2000: 44-47.
[10]	Przybylinski R W, DeCaire. Radar Signatures Associated with the Derecho, One Type of Mesoscale Convective System. Preprints, 14th Conf on Severe Local Storms, Indianapolis, IN, American Meteorology Society, 1985: 461-465.
[11]	张鸿发, 龚乃虎, 贾维, 等. 平凉地区强对流钩状回波特征的观测研究. 大气科学, 1997, 21, (3): 401–412.
[12]	Akos H, Istvan G. Severe Convective storms and associated phenomena in Hungary. Atmosphere Research, 2001, 56: 127–146. DOI:10.1016/S0169-8095(00)00094-6
[13]	Rudolf Katlenbo ck. The outbreak of severe storms along convergence lines northeast of the Alps. Case study of the 3 August 2001 mesoscale convective system with a pronounced bow echo. Atmospheric Research, 2004, 70: 55–75. DOI:10.1016/j.atmosres.2003.11.003
[14]	Weisman M L, Trapp R J. Low-level mesovorteces within squall lines and bow echoes. Part Ⅰ: Overview and dependence on environmental sheer. Mon Wea Rev, 2003, 131: 2779–2803. DOI:10.1175/1520-0493(2003)131<2779:LMWSLA>2.0.CO;2
[15]	Trapp R J, Weisman M L. Low-level mesovortices within squall lines and bow echos. Part Ⅱ: Their gengesis and implications. Mon Wea Rev, 2003, 131: 2804–2823. DOI:10.1175/1520-0493(2003)131<2804:LMWSLA>2.0.CO;2
[16]	Weisman M L, Davis C A. Mechanisms for the generation of mesoscale vortices within quasi-linear convective systems. J Atmos Sci, 1998, 55: 2603–2622. DOI:10.1175/1520-0469(1998)055<2603:MFTGOM>2.0.CO;2
[17]	http://www.skywarn.ampr.org/radar3.htm.
[18]	Xue Ming, Dan Dawson. Bright Bands, Bow Echoes and Mesoscale Convective Complexes, http://twister.ou.edu/MM2005/Chapter3.5.ppt.
[19]	Nolan T A, Justin M A, Lyndon S, et al. Rornadogenesis within Quasi-linear Convective Systems. Part Ⅱ: Preliminary WRF Simulation Results of the 29 June 1998 Derecho. 21st Conf on Severe Local Storms.http://ams.confex.com/ams/pdfpapers/46939.pdf.
[20]	徐枝芳, 党人庆, 葛文忠. 两个中尺度气旋性涡旋合并的数值模拟. 气候与环境研究, 2001, 6, (2): 173–179.
[21]	Schmocher G K, Przybylinski R W, Lin Y J. Forecasting the Initial Onset of Damaging Downburst Winds Associated with a Mesoscale Convective System (MCS) Using the Mid-altitude Radial Convergence (MARC) Signature. Preprints. 15th Conf on Weather Analysis and Forecasting, Norfolk, VA. Amer Meteor Soc, 1996: 306-311.
[22]	张沛源, 陈荣林. 多普勒速度图上的暴雨判据研究. 应用气象学报, 1995, 6, (3): 373–378.
[23]	孙建华, 赵思维. 华南"94·6"特大暴雨的中尺度对流系统及其环境场研究Ⅱ.物理过程、环境场以及地形对中尺度对流系统的作用. 大气科学, 2002, 26, (5): 633–646.


图 1. 2003年4月12日00:00 850 hPa天气形势图 Fig 1. Backgroud surrouding situation at 850 hPa, 00:00, Apr 12, 2003


图 2. 2003年4月12日05:30建阳雷达反射率因子图 (距离每圈: 100 km，仰角: 1.5°) Fig 2. Radar reflectivity of Jianyang, 05:30, Apr 12, 2003 (the range is 100 km, the elevation is 1.5°)


图 3. 2003年4月12日05:48—10:12建阳雷达1.5°仰角回波前沿示意图 (距离每圈100 km) Fig 3. The frontal of 1.5°elevation PPI reflectivity from 05:48 to 10:12 (the range is 100 km)


图 4. 2003年04月12日08:15建阳雷达反射率因子图 (距离每圈: 40km) (a) 1.5°仰角，(b) 2.4°仰角 Fig 4. Radar reflectivity of Jianyang, 08:15, Apr 12, 2003 (the range is 40 km) (a) 1.5°elevation, (b) 2.4°elevation


图 5. 2003年04月12日08:15建阳雷达1.5°仰角径向速度图 (距离每圈: 50 km，最外圈: 30 km) Fig 5. Radar PPI velocity at 1.5° elevation in Jianyang, 08:15, Apr 12, 2003 (the range is 50 km, the outermost circle is 30 km)


图 6. 2003年4月12日08:15建阳雷达313°方位角，125.9 km的垂直剖面 (a) 反射率因子剖面，（b) 径向速度剖面 Fig 6. Cross section at 313° elevation of Jianyang Radar, 125.9 km, 08:15, Apr 12, 2003 (a) reflectivity cross section, (b) velocity cross section


图 7. 2003年4月12日08:15建阳雷达1.5°仰角反射率因子图 (距离每圈: 50 km, 最外圈: 30 km) Fig 7. Radar reflectivity at 1.5° elevation of Jianyang, 08:15, Apr 12, 2003 (the range is 50 km, the outermost circle is 30 km)


图 8. 2003年4月12日06:00 500 hPa上升速度差异场分布图 (黑色等值线表示地形高度，单位: m) Fig 8. Difference of vertical velocity distribution at 500 hPa, 06:00, Apr 12, 2003 (black lines indicate altitude, unit: m)


图 9. 2003年4月12日10:00模式模拟900 hPa流场 (图中彩色阴影为反射率因子，单位: dBz，红色框内为气旋性结构，绿色框内为反气旋性结构） Fig 9. Model simulated stream at 900 hPa, 10:00, Apr 12, 2003 (shading areas indicate radar reflectivity, unit: dBz; structure in red pane is cyclonic and the one in green is anti-cyclonic)


应用气象学报 2007, 18 (1): 42-49	PDF