一次典型东风波极端暴雨的中尺度特征及地形影响分析

doi:10.11755/j.issn.1006-7639(2022)-01-0073

摘要/Abstract

摘要：

利用湖南省常规气象观测资料、区域自动站资料、NCEP再分析资料、常德多普勒雷达资料,分析2016年8月8—15日在多个东风波倒槽接力影响下,湘北地区反复出现的极端暴雨天气的中尺度特征,并利用WRF-ARW中尺度数值模式,对8月10—11日湘北地区极端暴雨过程进行数值模拟和地形敏感性试验。结果表明:(1)1604号台风在广东深圳登陆后沿西北路径移动和1605号台风在西北太平洋向北移动后,副热带高压快速西伸控制华东及沿海地区,其底部的东风波扰动为极端暴雨提供了环流背景;(2)近地面不均匀加热为东风波槽附近强对流提供了充足的热力不稳定条件,地面中尺度辐合线为对流的触发和加强起到重要作用;(3)东风波槽带来的边界层暖湿气流在武陵山东侧激发深厚中尺度涡旋,是极端暴雨形成的主要原因;(4)地形敏感性试验进一步验证了东风波暖湿气流在武陵山脉地形抬升和阻挡作用下,在迎风坡上游地区形成气旋性辐合导致暴雨增幅。

关键词: 东风波, 极端强降水, 武陵山脉, 地形敏感性试验

Abstract:

Based on conventional observation data, regional automatic station data of Hunan Province, NCEP reanalysis data and Changde Doppler radar data, the mesoscale characteristic of extreme rainstorms occurring repeatedly in the north of Hunan Province from 8 to 15 August 2016 affected by several easterly waves was analyzed comprehensively. The effect of the Wuling mountains topography on rainfall increase was further verified by WRF-ARW mesoscale numerical experiments. The results are as follows: (1) After the typhoon 1604 landing at Shenzhen of Guangdong Province and moving northwestward and the typhoon 1605 moving northward, the western Pacific subtropical high rapidly extended westward and controled east China and coastal areas. At this time, the easterly wave disturbance at the bottom of the subtropical high provided the circulation background for extreme rainstorms. (2) The non-uniform heating near the ground provided sufficient thermal instability for the strong convection near the easterly wave trough, the surface mesoscale convergence line played an important role in triggering and strengthening the convection. (3) During the eastward movement of the boundary-layer warm moist air, a deep mesoscale vortex formed in east side of the Wuling mountains, which was the main reasons for the extreme rainstorm formation. (4) The topographic numerical sensitivity experiment further verified that the existence of the Wuling mountains was beneficial to the development and maintenance of strong convection on the east side of the mountain under the guidance of the easterly wind flow.

Key words: easterly wave, extreme precipitation, the Wuling mountains, orographic experiment

中图分类号:

P458.1⁺21.1

胡振菊, 黎璐, 黄小玉, 何炳文, 叶日新. 一次典型东风波极端暴雨的中尺度特征及地形影响分析[J]. 干旱气象, 2022, 40(1): 73-83.

HU Zhenju, LI Lu, HUANG Xiaoyu, HE Binwen, YE Rixin. Analysis of mechanism of topographic influence and meso-scale convective characteristics of an extremely severe rainfall affected by typical easterly wave[J]. Journal of Arid Meteorology, 2022, 40(1): 73-83.

图/表 13

图1 模式嵌套区域及地形分布(单位:km)

Fig.1 The setting of mode domain and the topography distribution (Unit: km)

图2 2016年7月29日至8月9日1604和1605号台风路径(a),2016年8月10日08:00(b)、14:00(c)、11日02:00(d)500 hPa位势高度场(等值线,单位:dagpm)、850 hPa涡度场(阴影,单位:10-5 s-1)及风场(箭矢,单位:m·s-1) (红色线包围区域为湖南省,下同)

Fig.2 The tracks of the typhon 1604 and 1605 from 29 July to 9 August 2016 (a), the geopotential height field (the isolines, Unit: dagpm) on 500 hPa, vorticity field (the shaded, Unit: 10-5 s-1) and wind field (the vectors, Unit: m·s-1) on 850 hPa at 08:00 BST 10 (b), 14:00 BST 10 (c) and 02:00 BST 11 (d) August 2016 (the area in the red border for Hunan Province, the same as below)

图3 2016年8月7—15日常德站风场(箭矢,单位:m·s-1)及垂直速度 (阴影,单位:Pa·s-1)的时间-高度剖面

Fig.3 The height-time sections of wind field (the vectors, Unit: m·s-1) and vertical velocity (the shaded, Unit: Pa·s-1) at Changde station from 7 to 15 August 2016

图4 2016年8月8日20:00至9日08:00(a)、9日20:00至10日08:00(b)、10日20:00至11日08:00(c)湖南累计降水量(单位:mm)空间分布及8月11日01:00—07:00杨板乡站逐时降水量(d)

Fig.4 The distribution of accumulative precipitation (Unit: mm) from 20:00 BST 8 to 08:00 BST 9 (a), 20:00 BST 9 to 08:00 BST 10 (b) and 20:00 BST 10 to 08:00 BST 11 (c) in Hunan Province, hourly precipitation of Yangban township station from 01:00 BST to 07:00 BST 11 August 2016

图5 2016年8月10日22:35(a)、11日02:19(b)常德多普勒雷达组合反射率因子(单位:dBZ)及沿图5(b)中蓝色直线的反射率因子垂直剖面(c, 单位:dBZ)及风暴属性(d)

Fig.5 The combined reflectivity factor of Changde Doppler radar at 22:35 BST 10 (a) and 02:19 BST 11 (b) (Unit: dBZ) August, the vertical section of base reflectivity factor along the blue solid line in Fig.5b (c, Unit: dBZ) and the radar storm properties (d)

图6 2016年8月11日02:25常德多普勒雷达0.5°(a)、1.5°(b)仰角径向速度(单位:m·s-1)及11日02:00—04:00杨板乡站逐分钟降水量(c)

Fig.6 The radial velocity on 0.5° (a) and 1.5° (b) elevation of Changde Doppler radar at 02:25 BST 11 August (Unit: m·s-1), the minutely precipitation at the Yangban township station from 02:00 BST to 04:00 BST 11 (c) August 2016

图7 2016年8月10日23:00(a)和11日02:00(b)湖南省区域站风场(风矢量,单位:m·s-1)和过去6 h降水量(阴影,单位:mm)

Fig.7 The wind field (the vectors, Unit: m·s-1) and past 6 hours precipitation (the shaded, Unit: mm) of regional stations in Hunan Province at 23:00 BST 10 (a) and 02:00 BST 11 (b) August 2016

图8 2016年8月10日20:00(a、c、d)、11日02:00(b)850 hPa风场(箭矢,单位:m·s-1)和水汽通量散度(阴影,单位:10-5 g·hPa-1·cm-2·s-1)(a、b),850 hPa风场(箭矢,单位:m·s-1)和假相当位温θse(阴影,单位:K)(c), 500 hPa风场(箭矢,单位:m·s-1)及Δθse850-500(阴影,单位:K)(d)

Fig.8 The wind field (the vectors, Unit: m·s-1) and water vapor flux divergence (the shaded, Unit: 10-5 g·hPa-1·cm-2·s-1) on 850 hPa (a, b), the wind field (the vectors, Unit: m·s-1) and θse (the shaded, Unit: K) on 850 hPa (c), the wind field (the vectors, Unit: m·s-1) on 500 hPa and Δθse850-500 (the shaded, Unit: K) (d) at 20:00 BST 10 (a, c, d) and 02:00 BST 11 (b) August 2016

表1 2016年8月10日22:00至11日05:00雨强大于20 mm·h-1的中尺度雨团演变

Tab.1 The development of mesoscale rain cluster with rainfall intensity more than 20 mm·h-1 from 22:00 BST 10 to 05:00 BST 11 August 2016

时段	雨强大于20 mm·h^-1的站数	最大雨强/(mm·h^-1)	所属县
10日22:00—23:00	1	20.7	汉寿
10日23:00—00:00	10	34.9	安乡
11日00:00—01:00	34	83.3	安乡
11日01:00—02:00	35	52.0	临澧
11日02:00—03:00	41	93.8	临澧
11日03:00—04:00	46	93.3	石门
11日04:00—05:00	34	58.8	澧县

图9 控制试验(a)和敏感性试验(b)模拟的2016年8月10日20:00至11日08:00累计降水量(单位:mm)分布

Fig.9 The distribution of accumulated precipitation simulated by control test (a) and sensitivity test (b) from 20:00 BST 10 to 08:00 BST 11 August 2016 (Unit: mm)

图10 2016年8月10日20:00至11日20:00控制试验(a)和敏感性试验(b)模拟的杨板乡站风场(箭矢,单位:m·s-1)及垂直速度(阴影,单位:m·s-1)的高度-时间剖面

Fig.10 The height-time sections of wind field (the vectors, Unit: m·s-1) and vertical velocity (the shaded, Unit: m·s-1) simulated by control test (a) and sensitivity test (b) at Yangban township station from 20:00 BST 10 to 20:00 BST 11 August 2016

图11 2016年8月11日04:00控制试验(a)和敏感性试验(b)模拟的湘北区域0.5 km风场(箭矢,单位:m·s-1)和雷达反射率(阴影,单位: dBZ) (+为暴雨中心)

Fig.11 Distribution of the 0.5 km wind field (the vectors, Unit: m·s-1) and radar reflectivity (the shaded, Unit: dBZ) by control test (a) and sensitivity test (b) at 04:00 BST 11 August 2016 in northern Hunan area (+ indicates the location of rainstorm)

图12 2016年8月11日03:00—06:00控制试验和敏感性试验模拟的杨板乡站垂直速度廓线 (a)03:00,(b)04:00,(c)05:00,(d)06:00

Fig.12 The vertical velocity profiles simulated by control test and sensitivity test at Yangban township station from 03:00 BST to 06:00 BST 11 August 2016 (a) 03:00 BST, (b) 04:00 BST, (c) 05:00 BST, (d) 06:00 BST

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