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晴空回波在强对流天气临近预报中的应用
The Application of Clear air Echo to Early Warning of Severe Convective Weather
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摘要: 该文介绍了利用多普勒天气雷达资料判断环境风场辐合、辐散的两种方法：径向速度图像特征定性识别法和EVAD技术定量计算法，并结合2009年8月两次强对流天气过程详细介绍了两种方法的具体应用。统计分析了2005—2008年5—9月晴空回波特征以及不同高度散度和对流出现时间的关系, 晴空回波出现在距离雷达中心50 km范围之内，反射率因子多在10~20 dBZ，径向速度大部分为-5~5 m/s；强对流天气出现之前，对流层低层均会出现辐合，可以利用低层连续5个体扫出现辐合作为环境场具有辐合条件的指标。根据统计结果建立了强对流天气临近预警系统，该系统在2009年6—8月试运行，预警命中率为88.9%，虚警率为29.8%，临界成功指数为64.5%，辐合提前对流天气出现时间平均为7.1 h，对降低强对流天气漏报率，提高强对流天气的临近预报水平有重要意义。Abstract: Using Doppler weather radar data, two methods are implemented to estimate the divergence of environmental wind field. The first method is radial velocity image qualitative identification, through which the wind divergence is qualitatively judged by calculating the difference between positive and negative radial velocity area, and the wind speed given by comparing the value of positive and negative radial velocity in the same range rings. The other is EVAD (Extended Velocity Azimuth Display) quantitative analysis, which estimates the divergence of each level in 10—50 km around radar. They are applied in the analysis of two strong convective weather processes occurred in August 2009. The relationships between clear air echo characteristics, divergence in different levels and the time of convection appearance are statistically investigated by analyzing 50 processes from May to September during 2005 to 2008. It's found that clear air echo appears within 50 km from radar center, the reflectivity are 10—20 dBZ, and the radial velocity is about±5 m/s. There are always convergences in low levels before convective weather, so it can be used as indicator of convergent environment field when consecutive five convergences appear on low level. As the altitude lowers, convergence happens ahead of convective weather much more, and on the level of 0.5 km, the forecast time of simple rainstorm can bring forward longer than that of simultaneous multiform convective weather.
Based on the results, a severe convective weather automatic warning system (SWEAWAR) is established and run on trial from June to August of 2009 except for 5 days without radar records. Among the 57 warnings, the hit ratio is 88.9% and false warnings ratio is 29.8%, the critical success index for the early warning is 64.5% and the convergence occurs 7.1 hours ahead of the convective weather on average. The SWEAWAR system seldom misses but generate quite a few false warnings too. Overall, it can help to reduce the missing report rate and improve forecast of severe convective weather.-
Key words:
- clear-air echoes;
- convective weather;
- early warning
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图 1 2009年8月3日22:30—4日08:30径向速度PPI演变 (0.5°仰角, 相邻距离圈间隔为25 km)
Fig. 1 The radial velocity PPIs from 22:30 3 August to 08:30 4 August 2009 (elevaton is 0.5°, the interval of adjacent rings is 25 km)
图 2 2009年8月3日19:54—4日02:36不同高度层散度随时间变化曲线
Fig. 2 The time series of the divergence at different height from 19:54 3 August to 02:36 4 August in 2009
图 3 2009年8月4日07:54—13:00不同高度层散度随时间变化曲线
Fig. 3 The time series of the divergence at different height from 07:54 to 13:00 on 4 August 2009
图 4 2009年8月27日12:00—15:30径向速度PPI演变 (1.5°仰角, 相邻距离圈间隔为25 km)
Fig. 4 The time series of the radial velocity PPIs from 12:00 to 15:30 on 27 August 2009 (the elevation is1.5°, the interval of adjacent rings is 25 km)
图 5 2009年8月27日11:54—19:00不同高度层散度随时间变化曲线
Fig. 5 The time series of the divergence at different height from 11:54 to 19:00 on 27 August 2009
表 1 0~500 m高度内不同仰角对应的距离圈数
Table 1 The rings in the height of 0—500 m in each elevation angles
表 2 不同高度辐合分析
Table 2 The analysis of convergence at diffrent height
表 3 2009年6—8月灾害性天气评分情况表
Table 3 The score sheet of severe weather from June to August in2009
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[1] 何立富,陈涛,周庆亮,等.北京"7.10"暴雨β-中尺度对流系统分析.应用气象学报,2007,18(5):655-665. http://qikan.camscma.cn/jams/ch/reader/view_abstract.aspx?file_no=200705100&flag=1 [2] 赵玮,王建捷.北京2006年夏季接连两场暴雨的观测对比分析.气象,2008,34(8):3-14. http://www.cnki.com.cn/Article/CJFDTOTAL-QXXX200808002.htm [3] 王飞,张义军,赵均壮,等.雷达资料在孤立单体雷电预警中的初步应用.应用气象学报,2008,19(2):153-160. http://qikan.camscma.cn/jams/ch/reader/view_abstract.aspx?file_no=20080228&flag=1 [4] 夏文梅,张亚萍,汤达章.暴雨多普勒天气雷达资料的分析.南京气象学院学报,2002,25(6):787-794. http://www.cnki.com.cn/Article/CJFDTOTAL-NJQX200206008.htm [5] 马清云,李泽椿,陶士伟.单部多普勒天气雷达风场反演及其在数值预报中的应用试验.应用气象学报,2001,12(4):488-493. http://qikan.camscma.cn/jams/ch/reader/view_abstract.aspx?file_no=20010463&flag=1 [6] 徐广阔,孙建华,雷霆,等.多普勒天气雷达资料同化对暴雨模拟的影响.应用气象学报,2009,20(1):36-46. http://qikan.camscma.cn/jams/ch/reader/view_abstract.aspx?file_no=20090105&flag=1 [7] 王楠,刘黎平,徐宝祥,等.利用多普勒雷达资料识别低空风切变和辐合线方法研究.应用气象学报,2007,18(3):314-320. http://qikan.camscma.cn/jams/ch/reader/view_abstract.aspx?file_no=20070353&flag=1 [8] 程向阳,王兴荣,胡雯,等.雷暴天气在多普勒雷达资料上的前兆特征分析.气象科学,2003.23(4):485-490. http://www.cnki.com.cn/Article/CJFDTOTAL-QXKX200304013.htm [9] 李淑玲,刁秀广,朱敏,等.一次飑线过程多普勒雷达资料分析.气象,2009,35(3):60-65. http://www.cnki.com.cn/Article/CJFDTOTAL-XJQX200903014.htm [10] 朱敏华,姜有山,周红根.两次暴雨过程的多普勒天气雷达资料对比分析.气象科学,2005,23(1):71-78. http://www.cnki.com.cn/Article/CJFDTOTAL-QXKX200501009.htm [11] 王丽荣,胡志群,汤达章,等.多普勒雷达径向速度资料在对流天气预报中的应用.气象科学,2007,27(6):695-701. http://www.cnki.com.cn/Article/CJFDTOTAL-QXKX200706018.htm [12] 胡明宝,高太长,汤达章.多普勒天气雷达资料分析与应用.北京:解放军出版社,2000:113-115. [13] Wood V T,Brown R A.Single Doppler velocity signature interpretation of nondivergent environmental winds.J Atmos Ocean Technol,1986,3(1):114-128. doi: 10.1175/1520-0426(1986)003<0114:SDVSIO>2.0.CO;2 [14] Wood V T,Brown R A.Effects of radar proximity on single Doppler velocity signatures of axisymnetric rotation and divergence.Mon Wea Rev,1992,120:2798-2807. doi: 10.1175/1520-0493(1992)120<2798:EORPOS>2.0.CO;2 [15] 胡志群,汤达章,梁明珠,等.用改善的EVAD技术和变分法计算大气垂直速度.南京气象学院学报,2005,28(3):344-350. http://www.cnki.com.cn/Article/CJFDTOTAL-NJQX200503008.htm [16] Thomas M,Srivastava R C.An improved version of the extended velocity-azimuth display analysis of single-Doppler radar data.J Atmos Ocean Technol,1991,8(4):453-456. doi: 10.1175/1520-0426(1991)008<0453:AIVOTE>2.0.CO;2 -
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