Dual Polarization Radar Characteristics of Severe Downburst Occurred in Weak Vertical Wind Shear
-
摘要: 基于S波段双偏振多普勒天气雷达和常规观测资料, 分析发生于2022年6月26日、6月30日和7月2日弱垂直风切变环境下强下击暴流的双偏振特征, 探讨其物理机制。研究表明:3次强下击暴流的对流不稳定能量较强, 但垂直风切变较小。6·30风暴和7·2风暴低层较湿, 中(上)层略干, 6·26风暴除近地层外整层较干。在垂直风切变较弱且0℃层高度较高的环境下, 强下击暴流同时伴有高强度分钟降水量(超过3 mm)是其重要特征之一;强下击暴流产生前, 风暴强度较强且风暴顶较高(超过10 km), 0℃层及以上高度存在超过3.0°·km-1的差分相移率高值区, 表明液态粒子或融化的小冰相粒子浓度较高, 可视为风暴液态粒子质量团的悬垂, 类似于强反射率因子核的悬垂及下降, 诱发强下击暴流并伴有短时高强度降水;由于夹卷层平均风速较小, 该类强下击暴流动量下传机制较弱, 如果空气较湿, 强下击暴流的主要机制为重力拖曳及冰相粒子的融化作用, 如果空气较干, 还应考虑干空气的夹卷蒸发作用。Abstract: Based on S-band Dual polarization doppler radar data and conventional observations, characteristics of 3 severe downbursts occurred under the background of weak vertical wind shear are analyzed, and their possible physical formation mechanisms are studied. It shows that they all occur with high convective available potential energy, but the vertical wind shear (less than 10 m·s-1) of the environmental atmosphere is weak. 6·30 storm and 7·2 storm are featured by wetter air at low level and drier air at middle (or high) level, while the atmosphere air for 6·26 storm is dry from low level to high level except for the near surface layer. With weak wind vertical shear and higher 0℃ layer height, this type of severe downburst is mostly along with high intensity precipitation (over 3 mm per minute). Before the severe downbursts touch down, the storms grow intensively (over 60 dBZ) and expand over 10 km height, the differential reflectivity (ZDR) and specific differential phase shift (KDP) columns are higher over -10℃ layer, and KDP columns' area at -10℃ layer are larger than ZDR columns'. For dual polarization radar, the appearance of high KDP region (more than 3.0°·km-1) around or above 0℃ layer can be regard as a criterion for identifying downbursts. The high KDP region with high concentrations of liquid partials or small melting ice particles around or above 0℃ layer can be treated as the overhanging quality roll of liquid particles, which is similar to the overhanging and descending reflectivity core. The appearance and descending of high KDP region initiates the development of severe downburst along with short-time high intensity precipitation. Due to weak entrainmental zone mean wind speed, the contribution of downward momentum transportation mechanism on the surface gale wind is probably weak. If the environmental atmosphere is wet, the dominant formation mechanism for severe downburst is the gravity dragging effect by abundant liquid (or small melting ice) particles and a tiny quantity of big hail, and the subordinate formation mechanism is the melt cooling effect by ice phase particles. If the environmental atmosphere is dry especially at middle or high level, the entrainment effect and evaporative cooling effect by dry air also contribute to the maintenance and acceleration of downdrafts.
-
图 4 2022年6月26日14:54和15:00青岛双偏振雷达ZH,KDP和ZDR沿316.5°的径向垂直剖面
(紫色、红色和蓝色水平实线分别为湿球0℃层,0℃层和-20℃层高度)
Fig. 4 Cross-sections of ZH, KDP and ZDR along 316.5° radial direction by Qingdao dual polarization radar at 1454 BT and 1500 BT on 26 Jun 2022 (purple, red and blue horizontal solid lines denote heights of the wet bulb 0℃ layer, 0℃ layer and -20℃ layer, respectively)
图 6 2022年6月30日12:37和12:42济南双偏振雷达ZH,KDP和ZDR沿97°的径向垂直剖面
(紫色、红色和蓝色水平实线分别为湿球0℃层,0℃层和-20℃层高度)
Fig. 6 Cross-sections of ZH, KDP and ZDR along 97° radial direction by Qingdao dual polarization radar at 1237 BT and 1242 BT on 30 Jun 2022 (purple, red and blue horizontal solid lines denote heights of the wet bulb 0℃ layer, 0℃ layer and -20℃ layer, respectively)
图 8 2022年7月2日15:31和15:37济宁双偏振雷达ZH和KDP沿258°的径向垂直剖面
(紫色、红色和蓝色水平实线分别为湿球0℃层,0℃层和-20℃层高度)
Fig. 8 Cross-sections of ZH and KDP along 258° radial direction by Jining dual polarization radar at 1531 BT and 1537 BT on 2 Jul 2022 (purple, red and blue horizontal solid lines denote heights of the wet bulb 0℃ layer, 0℃ layer layer and -20℃ layer, respectively)
表 1 青岛站、章丘站和郑州站探空环境物理量
Table 1 Environmental physical parameters obtained by sounding at Qingdao, Zhangqiu and Zhengzhou
物理量 青岛站
2022-06-26T08:00章丘站
2022-06-30T08:00郑州站
2022-07-02T08:00K指数/℃ -5.5 35 35 850 hPa和500 hPa的温差/℃ 30 25 26 有利抬升指数/℃ -6.8 -4.1 -3.9 对流有效位能/(J·kg-1) 1880 1010 1820 对流抑制位能/(J·kg-1) 0 0 0 600 hPa下沉对流有效位能/(J·kg-1) 1760 470 935 0~6 km垂直风切变/(m·s-1) 5.9 9.7 5.9 0~3 km垂直风切变/(m·s-1) 6.6 10.4 4.3 整层比湿度积分/(g·kg-1) 2810 4186 4109 干层强度/℃ 45 6 13.5 夹卷层平均风速/(m·s-1) 8.2 9.9 5.0 湿球0℃层高度/km 3.2 4.2 4.1 0℃层高度/km 4.9 4.4 4.9 -10℃层高度/km 6.7 6.2 6.6 -20℃层高度/km 8.1 7.9 8.2 表 2 风暴雷达特征
Table 2 Radar characteristics for storms
风暴 ZDR柱高度/km KDP柱高度/km -10℃层ZDR柱面积/(距离库数量) -10℃层KDP柱面积/(距离库数量) T-2 T-1 T T-2 T-1 T T-2 T-1 T T-2 T-1 T 6·26 6.7 6.7 7.5 7.5 8.8 7.5 8 5 6 35 20 5 6·30 6.8 6.8 6.7 9.1 7.5 7.1 6 3 7 8 11 6 7·2 8.0 8.0 9.3 8.5 28 9 47 34 -
[1] Fujita T T.Manual of Downburst Identification for Project NIMROD.SMRP Research Paper156.Chicago: University of Chicago, 1978: 1-104. [2] 郑永光, 周康辉, 盛杰, 等. 强对流天气监测预报预警技术进展. 应用气象学报, 2015, 26(6): 641-657. doi: 10.11898/1001-7313.20150601Zheng Y G, Zhou K H, Sheng J, et al. Advances in techniques of monitoring, forecasting and warning of severe convective weather. J Appl Meteor Sci, 2015, 26(6): 641-657. doi: 10.11898/1001-7313.20150601 [3] Fujita T T, Byers H R. Spearhead echo and downburst in the crash of an airliner. Mon Wea Rev, 1977, 105(2): 129-146. doi: 10.1175/1520-0493(1977)105<0129:SEADIT>2.0.CO;2 [4] Johns R H, Doswell C A Ⅲ. Severe local storms forecasting. Wea Forecasting, 1992, 7(4): 588-612. doi: 10.1175/1520-0434(1992)007<0588:SLSF>2.0.CO;2 [5] 高晓梅, 俞小鼎, 王令军, 等. 山东半岛两次海风锋引起的强对流天气对比. 应用气象学报, 2018, 29(2): 245-256. doi: 10.11898/1001-7313.20180210Gao X M, Yu X D, Wang L J, et al. Comparative analysis of two strong convections triggered by sea-breeze front in Shandong Peninsula. J Appl Meteor Sci, 2018, 29(2): 245-256. doi: 10.11898/1001-7313.20180210 [6] 王黉, 李英, 宋丽莉, 等. 川藏地区雷暴大风活动特征和环境因子对比. 应用气象学报, 2020, 31(4): 435-446. doi: 10.11898/1001-7313.20200406Wang H, Li Y, Song L L, et al. Comparison of characteristics and environmental factors of thunderstorm gales over the Sichuan-Tibet Region. J Appl Meteor Sci, 2020, 31(4): 435-446. doi: 10.11898/1001-7313.20200406 [7] 王黉, 李英, 文永仁. 川藏高原一次混合型强对流天气的观测特征. 应用气象学报, 2021, 32(5): 567-579. doi: 10.11898/1001-7313.20210505Wang H, Li Y, Wen Y R. Observational characteristics of a hybrid severe convective event in the Sichuan-Tibet Region. J Appl Meteor Sci, 2021, 32(5): 567-579. doi: 10.11898/1001-7313.20210505 [8] 盛杰, 郑永光, 沈新勇, 等. 2018年一次罕见早春飑线大风过程演变和机理分析. 气象, 2019, 45(2): 141-154. https://www.cnki.com.cn/Article/CJFDTOTAL-QXXX201902001.htmSheng J, Zheng Y G, Shen X Y, et al. Evolution and mechanism of a rare squall line in early spring of 2018. Meteor Mon, 2019, 45(2): 141-154. https://www.cnki.com.cn/Article/CJFDTOTAL-QXXX201902001.htm [9] 俞小鼎, 张爱民, 郑媛媛, 等. 一次系列下击暴流事件的多普勒天气雷达分析. 应用气象学报, 2006, 17(4): 385-393. doi: 10.3969/j.issn.1001-7313.2006.04.001Yu X D, Zhang A M, Zheng Y Y, et al. Doppler radar analysis on a series of downburst events. J Appl Meteor Sci, 2006, 17(4): 385-393. doi: 10.3969/j.issn.1001-7313.2006.04.001 [10] Przybylinski R W. The bow echo: Observations, numerical simulations, and severe weather detection methods. Wea Forecasting, 1995, 10(2): 203-218. doi: 10.1175/1520-0434(1995)010<0203:TBEONS>2.0.CO;2 [11] Smull B F, Houze R A Jr. Rear inflow in squall line with trailing stratiform precipitation. Mon Wea Rev, 1987, 115(12): 2869-2889. doi: 10.1175/1520-0493(1987)115<2869:RIISLW>2.0.CO;2 [12] Eilts M D, Johnson J T, Mitchell E D, et al. Damaging Downburst Prediction and Detection Algorithm for the WSR-88D//Preprints, 18th Conference on Severe Local Storms. San Francisco, CA, Amer Meteor Soc, 1996: 541-545. [13] 王秀明, 周小刚, 俞小鼎. 雷暴大风环境特征及其对风暴结构影响的对比研究. 气象学报, 2013, 71(5): 839-852. https://www.cnki.com.cn/Article/CJFDTOTAL-QXXB201305004.htmWang X M, Zhou X G, Yu X D. Comparative study of environmental characteristics of a windstorm and their impacts on storm structures. Acta Meteor Sinica, 2013, 71(5): 839-852. https://www.cnki.com.cn/Article/CJFDTOTAL-QXXB201305004.htm [14] 王福侠, 俞小鼎, 裴宇杰, 等. 河北省雷暴大风的雷达回波特征及预报关键点. 应用气象学报, 2016, 27(3): 342-351. doi: 10.11898/1001-7313.20160309Wang F X, Yu X D, Pei Y J, et al. Radar echo characteristics of thunderstorm gales and forecast key points in Hebei Province. J Appl Meteor Sci, 2016, 27(3): 342-351. doi: 10.11898/1001-7313.20160309 [15] 王一童, 王秀明, 俞小鼎. 产生致灾大风的超级单体回波特征. 应用气象学报, 2022, 33(2): 180-191. doi: 10.11898/1001-7313.20220205Wang Y T, Wang X M, Yu X D. Radar characteristics of straight-line damaging wind producing supercell storms. J Appl Meteor Sci, 2022, 33(2): 180-191. doi: 10.11898/1001-7313.20220205 [16] 王易, 郑媛媛, 庄潇然, 等. 江苏典型下击暴流风暴结构特征统计分析. 气象学报, 2022, 80(4): 592-603. https://www.cnki.com.cn/Article/CJFDTOTAL-QXXB202204008.htmWang Y, Zheng Y Y, Zhuang X R, et al. Statistical analysis of the structural characteristics of typical downbursts in Jiangsu Province, China. Acta Meteor Sinica, 2022, 80(4): 592-603. https://www.cnki.com.cn/Article/CJFDTOTAL-QXXB202204008.htm [17] 王秀明, 俞小鼎, 费海燕, 等. 下击暴流形成机理及监测预警研究进展. 气象, 2023, 49(2): 129-145. https://www.cnki.com.cn/Article/CJFDTOTAL-QXXX202302001.htmWang X M, Yu X D, Fei H Y, et al. A review of downburst genesis mechanism and warning. Meteor Mon, 2023, 49(2): 129-145. https://www.cnki.com.cn/Article/CJFDTOTAL-QXXX202302001.htm [18] 吴翀, 刘黎平, 仰美霖, 等. X波段双偏振雷达相态识别与拼图的关键技术. 应用气象学报, 2021, 32(2): 200-216. doi: 10.11898/1001-7313.20210206Wu C, Liu L P, Yang M L, et al. Key technologies of hydrometeor classification and mosaic algorithm for X-band polarimetric radar. J Appl Meteor Sci, 2021, 32(2): 200-216. doi: 10.11898/1001-7313.20210206 [19] 李哲, 吴翀, 刘黎平, 等. 双偏振相控阵雷达误差评估与相态识别方法. 应用气象学报, 2022, 33(1): 16-28. doi: 10.11898/1001-7313.20220102Li Z, Wu C, Liu L P, et al. Error evaluation and hydrometeor classification method of dual polarization phased array radar. J Appl Meteor Sci, 2022, 33(1): 16-28. doi: 10.11898/1001-7313.20220102 [20] 郭飞燕, 刁秀广, 马艳, 等. 山东一次飑线双偏振结构与地面降水滴谱特征分析. 气象学报, 2023, 81(2): 328-339. https://www.cnki.com.cn/Article/CJFDTOTAL-QXXB202302010.htmGuo F Y, Diao X G, Ma Y, et al. Characteristics of the dual-polarization structure and raindrop size distribution of a squall line in Shandong. Acta Meteor Sinica, 2023, 81(2): 328-339. https://www.cnki.com.cn/Article/CJFDTOTAL-QXXB202302010.htm [21] 刁秀广, 李芳, 万夫敬. 两次强冰雹超级单体风暴双偏振特征对比. 应用气象学报, 2022, 33(4): 414-428. doi: 10.11898/1001-7313.20220403Diao X G, Li F, Wan F J. Comparative analysis on dual polarization features of two severe hail supercells. J Appl Meteor Sci, 2022, 33(4): 414-428. doi: 10.11898/1001-7313.20220403 [22] Kumjian M R, Ganson S M, Ryzhkov A V. Freezing of rain drops in deep convective updrafts: A microphysical and polarimetric model. J Atmos Sci, 2012, 69(12): 3471-3490. [23] 刁秀广, 郭飞燕. 2019年8月16日诸城着急单体风暴双偏振参量结构特征分析. 气象学报, 2021, 79(2): 181-195. https://www.cnki.com.cn/Article/CJFDTOTAL-QXXB202102001.htmDiao X G, Guo F Y. Analysis of polarimetric signatures in the supercell thunderstorm occurred in Zhucheng on 16 August 2019. Acta Meteor Sinica, 2021, 79(2): 181-195. https://www.cnki.com.cn/Article/CJFDTOTAL-QXXB202102001.htm [24] Loney M L, Zrnić D S, Straka J M, et al. Enhanced polarimetric radar signatures above the melting level in a supercell storm. J Appl Meteor, 2002, 41(12): 1179-1194. [25] van Lier-Walqui M, Fridlind A M, Ackerman A S, et al. On polarimetric radar signatures of deep convection for model evaluation: Columns of specific differential phase observed during MC3E. Mon Wea Rev, 2016, 144(2): 737-758. [26] Wakimoto R M, Bringi V N. Dual-polarization observations of microbursts associated with intense convection: The 20 July storm during the MIST project. Mon Wea Rev, 1988, 116(8): 1521-1539. [27] Scharfenberg K A. Polarimetric Radar Signatures in Microburst-producing Thunderstorms//31st Int Conf on Radar Meteorology. Seattle: Amer Meteor Soc, 2003, 8B4. [28] Kuster C M, Heinselman P L, Schuur, T J. Rapid-update radar observations of downbursts occurring within an intense multicell thunderstorm on 14 June 2011. Wea Forecasting, 2016, 31(3): 827-851. [29] Kuster C M, Bowers B R, Carlin J T, et al. Using KDP cores as a downburst precursor signature. Wea Forecasting, 2021, 36(4): 1183-1198. [30] Wang X, Wang H L, He J X, et al. Automated recognition of macro downburst using Doppler weather radar. Atmos, 2022, 13(5). DOI: 10.3390/atmos13050672. [31] Smith T M, Elmore K L, Dulin, S A. A damaging downburst prediction and detection algorithm for the WSR-88D. Wea Forecasting, 2004, 19(2): 240-250. [32] Miller P W, Mote T L. Characterizing severe weather potential in synoptically weakly forced thunderstorm environments. Nat Hazards Earth Syst Sci, 2018, 18: 1261-1277. [33] 俞小鼎, 王秀明, 李万莉, 等. 雷暴与强对流临近预报. 北京: 气象出版社, 2020.Yu X D, Wang X M, Li W L, et al. Thunderstorm and Strong Convection Nowcasting. Beijing: China Meteorological Press, 2020. [34] McCarthy J, Serafin R, Wilson J, et al. Addressing the microburst threat to aviation: Research-to-operations success story. Bull Amer Meteor Soc, 2022, 103(12). DOI: 10.1175/BAMS-D-22-0038.1. [35] 周后福, 刁秀广, 赵倩, 等. 一次连续下击暴流天气的成因分析. 干旱气象, 2017, 35(4): 641-648. https://www.cnki.com.cn/Article/CJFDTOTAL-GSQX201704015.htmZhou H F, Diao X G, Zhao Q, et al. Cause analysis of a continuous downburst weather. J Arid Meteor, 2017, 35(4): 641-648. https://www.cnki.com.cn/Article/CJFDTOTAL-GSQX201704015.htm [36] 马淑萍, 王秀明, 俞小鼎. 极端雷暴大风的环境参量特征. 应用气象学报, 2019, 30(3): 292-301. doi: 10.11898/1001-7313.20190304Ma S P, Wang X M, Yu X D. Environmental parameter characteristics of severe wind with extreme thunderstorm. J Appl Meteor Sci, 2019, 30(3): 292-301. doi: 10.11898/1001-7313.20190304 [37] 陈淑琴, 章丽娜, 俞小鼎, 等. 浙北沿海连续3次飑线演变过程的环境条件. 应用气象学报, 2017, 28(3): 357-368. doi: 10.11898/1001-7313.20170309Chen S Q, Zhang L N, Yu X D, et al. Environmental conditions of three squall lines in the north part of Zhejiang Province. J Appl Meteor Sci, 2017, 28(3): 357-368. doi: 10.11898/1001-7313.20170309 [38] 刘洪恩. 微下击暴流的特征及其数值模拟. 气象学报, 2001, 59(2): 183-195. https://cpfd.cnki.com.cn/Article/CPFDTOTAL-DIDD200109002A5E.htmLiu H E. Characteristics and numerical simulation of microburst. Acta Meteor Sinica, 2001, 59(2): 183-195. https://cpfd.cnki.com.cn/Article/CPFDTOTAL-DIDD200109002A5E.htm [39] Hubbert J C, Wilson J W, Weckwerth T M, et al. S-Pol's polarimetric data reveal detailed storm features (and insect behavior). Bull Amer Meteor Soc, 2018, 99(10): 2045-2060. [40] Ryzhkov A V, Kumjian M R, Ganson S M, et al. Polarimetric radar characteristics of melting hail. Part Ⅱ: Practical implications. J Appl Meteor Climatol, 2013, 52(12): 2871-2886. [41] 段亚鹏, 王东海, 刘英. "东方之星"翻沉事件强对流天气分析及数值模拟. 应用气象学报, 2017, 28(6): 666-677. doi: 10.11898/1001-7313.20170603Duan Y P, Wang D H, Liu Y. Radar analysis and numerical simulation of strong convective weather for "Oriental Star" depression. J Appl Meteor Sci, 2017, 28(6): 666-677. doi: 10.11898/1001-7313.20170603 [42] Mahale V N, Zhang G F, Xue M. Characterization of the 14 June 2011 Norman, Oklahoma, downburst through dual-polarization radar observations and hydrometeor classification. J Appl Meteor Climatol, 2016, 55(12): 2635-2655.