Environment Characteristics and Causes of a Continuous Hail Fall Event Occurred Within the Cold Air Mass to the North of a Cold Front

Xu Aihua; Chen Yunhui; Chen Tao; Zhang Juanjuan

Vol.24, NO.2, 2013

Article Contents

Article Navigation > Journal of Applied Meteorological Science > 2013 > 24(2): 197-206

Xu Aihua, Chen Yunhui, Chen Tao, et al. Environment characteristics and causes of a continuous hail fall event occurred within the cold air mass to the north of a cold front. J Appl Meteor Sci, 2013, 24(2): 197-206.

Citation:

Xu Aihua, Chen Yunhui, Chen Tao, et al. Environment characteristics and causes of a continuous hail fall event occurred within the cold air mass to the north of a cold front. J Appl Meteor Sci, 2013, 24(2): 197-206.

Citation:

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Environment Characteristics and Causes of a Continuous Hail Fall Event Occurred Within the Cold Air Mass to the North of a Cold Front

1.
Jiangxi Provincial Meteorological Observatory, Nanchang 330046
2.
National Meteorological Center, Beijing 100081

Received Date: 2012-08-06
Rev Recd Date: 2012-11-15
Publish Date: 2013-04-30

Abstract

Abstract

A continuous hail fall process occurred over Southern China during 24 February—5 March of 2009 is analyzed. This process happens under the background of typical continuous rain weather in spring over Southern China. During this period, a steady two-trough and one-ridge pattern maintains over the Euro-Asian, the stronger subtropical high is further north and west, the Indo-China Peninsula is occupied by a low trough, five short wave troughs move eastward from the Tibet Plateau, and 700 hPa warm-moist airflow is strong. The hail fall occurs within the cold air mass, 300—600 km north of the surface cold front. The vertical distribution of moisture presents dry over 500 hPa and wet (with the relative humidity more than 80%) under 500 hPa. The strong frontal zone in the middle and low levels exists between 25°—30°N of 850 hPa, with the temperature difference between south and north (frontal intensity) more than 14℃ per 5-latitude distances. There is a significant temperature inversion between 700—850 hPa. The 700 hPa southwest jet (≥20 m·s^-1) area ranges more than 1000 km. The 700—850 hPa vertical wind shear is strong, with the vector difference reaching 16—20 m·s^-1. Averagely, the temperature difference of 500—700 hPa exceeds 16℃, and the temperature lapse rate is about 0.74℃/100 m. The height of the 0℃ layer is very low (below 3 km). 500—700 hPa weak convective instability and symmetric instability may be the causes which result in the formation of this kind of hail. During the hail fall process, Δθ_se700-500 is 2—6℃ mostly. The minus baroclinic term of moist potential vorticity increases absolutely, which induces the southward expansion of the negative MVP value area. Meanwhile, MVP₁, MVP₂ and MVP present the variations that form or strengthen the latitudinal frontal zone. The hail fall happens on the south side of frontal zone, which is close to the negative MVP value area. The mechanism of this kind of hail formation is that the strong southwest airflow in middle troposphere lifts in the strong frontal zone, and induces the convective instability and symmetric instability. When trough passes over the strong frontal zone, the inclination of frontal surface becomes steep, the ascending motion strengthens, which form the typical elevated thunderstorm, and the ice embryo grows to hail in middle troposphere. This kind of trough often presents minus temperature variation or a preceding temperature trough. There is a melting layer in 700—850 hPa, and the thickness of upflow is small, therefore, the diameters of this kind of hail are less than 10 mm, few of them are 10—20 mm. The potential forecast index and criterion of this kind of hail falling area includes strong horizontal temperature frontal area, Δθ_se700-500 > 0℃ or T_700-500≥16℃, axis of 700 hPa is more than 20 m·s^-1 southwest airflow, area of strong 700-850 hPa vertical wind shear and 500 hPa shortwave trough.
- cold air mass;
- hail fall;
- frontal zone;
- elevated thunderstorm

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References(16)

Figures and Tables

Fig. 1 The averaged 500 hPa height (solid lines, unit: dagpm) with 24 h height-change line (dashed line, unit: dagpm)(a) and the sea level pressure (solid line, unit: hPa) with 10 m wind (barb)(b) from 24 Feb 2009 to 4 Mar 2009

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图 2 2009年2月26日 (a) 和3月1日 (b) 冰雹落区 (绿色) 天气系统配置图

(灰色：925 hPa切变和急流；红色：850 hPa切变和急流; 棕色：700 hPa切变和急流; 紫色：200 hPa急流; 急流后端的数值为急流核风速大小)

Fig. 2 Hailfall areas (green) on 26 Feb 2009(a) and 1 March 2009(b) with weather system configuration diagram

(gray: 925 hPa shear and jet; red: 850 hPa shear and jet; brown: 700 hPa shear and jet; purple: 200 hPa jet; figures denotes the velocity)

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Fig. 3 Time series diagrams for the wind at 25°N, 110°E and the relative humidity (the shaded area) during February—March 2009(a), and 850 hPa average wind and average temperature (contour, unit: ℃), average relative humidity (the shaded area) from 0800 BT 14 February to 2000 BT 4 March in 2009(b)

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Fig. 4 Soundings of Guiyang Station (a) and Changsha Station (b) at 2000 BT on 26 February 2009

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Fig. 5 Temperature difference between 700 hPa and 500 hPa (unit: ℃)(a) and the value of wind vector difference between 850 hPa and 700 hPa (unit: m·s^-1)(b) from 2000 BT 24 February to 2000 BT 4 March in 2009

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Fig. 6 Difference of θ_se between 700 hPa and 500 hPa during February—March in 2009(unit:℃)

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Fig. 7 Distribution of MPV₂ from 26 February to 3 March in 2009(unit: PVU)

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Fig. 8 Cross section of averaged θ_se (unit: ℃) along 110°E (a) and time series of 25°—30°N averaged vertical velocity (unit: Pa·s^-1) along 110°E (b) from 2000 BT 24 February to 2000 BT 3 March in 2009

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Fig. 9 Cross sections of θ_se(contour, unit: ℃), vertical velocity (shaded), and the flow field (stream line) at 1400 BT 26 February (a) and 2000 BT 26 February (b) in 2009 along 110°E

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Table 1 The hailfalls observed from 24 February to 5 March in 2009

省份	02-24	02-25	02-26	02-27	02-28	03-01	03-02	03-03	03-04	03-05
贵州	1(14)		11(9)	7(8)	6(6)	18(8)		4(20)
湖南	1(3)	3(8)	10(6)	12(8)	2(3)	8(7)	3(4)	33(12)	3(4)	1(7)
湖北	1(3)	4(5)	4(5)			1(2)
江西			3(4)					3(3)
注：括号中为最大冰雹直径，单位:mm。

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References

[1]	陆汉城, 杨国祥.中尺度天气原理和预报 (第二版).北京:气象出版社, 2004.
[2]	许焕斌, 田利庆.强对流云中"穴道"的物理意义和应用.应用气象学报, 2008, 19(3):372-379. doi: 10.11898/1001-7313.20080315
[3]	许焕斌, 段英.冰雹形成机制的研究并论人工雹胚与自然雹胚的"利益竞争"防雹假说.大气科学, 2001, 25(2):277-288. http://www.cnki.com.cn/Article/CJFDTOTAL-DQXK200102016.htm
[4]	洪延超, 肖辉, 李宏宇, 等.冰雹云中微物理过程研究.大气科学, 2002, 26(3):421-432. http://www.cnki.com.cn/Article/CJFDTOTAL-DQXK200203012.htm
[5]	康凤琴, 张强, 马胜萍, 等.青藏高原东北边缘冰雹形成机理.高原气象, 2004, 23(6):749-757. http://www.cnki.com.cn/Article/CJFDTOTAL-GYQX200406003.htm
[6]	王令, 郑国光, 康玉霞, 等.多普勒天气雷达径向速度图上的雹云特征.应用气象学报, 2006, 17(3):281-287. http://qikan.camscma.cn/jams/ch/reader/view_abstract.aspx?file_no=20060349&flag=1
[7]	朱敏华, 俞小鼎, 夏峰, 等.强烈雹暴三体散射的多普勒天气雷达分析.应用气象学报, 2006, 17(2):215-223. doi: 10.11898/1001-7313.20060213
[8]	王瑾, 刘黎平.WSR-88D冰雹探测算法在贵州地区的评估检验.应用气象学报, 2011, 22(1):96-106. doi: 10.11898/1001-7313.20110110
[9]	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.气象, 2011, 37(7):795-801. doi: 10.7519/j.issn.1000-0526.2011.07.003
[10]	许爱华, 马中元, 叶小峰.江西8种强对流天气形势与云型特征分析.气象, 2011, 37(10):1185-1195. doi: 10.7519/j.issn.1000-0526.2011.10.001
[11]	钱传海, 张金艳, 应冬梅, 等.2003年4月江西一次强对流天气过程的诊断分析.应用气象学报, 2007, 18(4):460-467. doi: 10.11898/1001-7313.20070406
[12]	闵晶晶, 刘还珠, 曹晓钟, 等.天津"6.25"大冰雹过程的中尺度特征及成因.应用气象学报, 2011, 22(5):525-536. doi: 10.11898/1001-7313.20110502
[13]	郭荣芬, 鲁亚斌, 高安生, 等.低纬高原罕见"雷打雪"中尺度特征分析.气象, 2009, 35(2):49-56. doi: 10.7519/j.issn.1000-0526.2009.02.008
[14]	李英, 段旭.湿位涡在云南冰雹天气分析时的应用.应用气象学报, 2000, 11(2):242-248. http://qikan.camscma.cn/jams/ch/reader/view_abstract.aspx?file_no=20000235&flag=1
[15]	许爱华, 何财富, 刘献耀.春季"冷区"冰雹天气分析及预报.江西气象科技, 1999, 22(1):14-16. http://www.cnki.com.cn/Article/CJFDTOTAL-HXQO199901004.htm
[16]	费建芳, 伍荣生, 宋金杰.对称不稳定理论的天气分析与预报应用研究进展.南京大学学报:自然科学版, 2009, 45(3):325-333. http://www.cnki.com.cn/Article/CJFDTOTAL-NJDZ200903000.htm