| 山东大风天气的低频特征及机理分析 |
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| 作者姓名： | 郑丽娜 刘冬冬 何鹏程 |
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| 作者单位： | （1.山东省气象防灾减灾重点实验室，山东 济南 250031; 2.济南市气象局，山东 济南 250102; 3.东营市垦利区气象局，山东 垦利 257500） |
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| 基金项目： | 山东省气象局重点科研项目（2019sdqxz09） |
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| 摘 要： | 利用山东省122个国家级地面气象观测站的风速数据与欧洲中期天气预报中心(ECMWF)提供的ERA-interim再分析数据,采用小波分析、带通滤波等方法对2015年9月—2020年9月山东的大风天气及相应的低频大气环流形势进行分析。结果表明,近几年山东的大风天气有增加的趋势,春季大风发生频次最多,秋季最少;山东半岛东部大风频次最多,鲁南地区最少;全年只有7月偏南大风站次较偏北大风多,其余月份多以偏北大风为主。山东大风具有显著的11～13 d与20～23 d的低频振荡周期。其中,春季大风以11～13 d的振荡周期为主,秋、冬季以20～23 d的振荡周期为主,夏季大风的振荡周期不明显。振荡周期的演变与大范围的大风过程有对应关系,大范围的大风过程大致发生在振荡的波峰处。春季偏北大风盛行时,多伴有经向风自北向南的传播。秋季大约以35°N为界,对流层中高层在35°N以北,经向风自南向北传播,35°N以南,则是自北向南传播,对流层中低层反之。山东春季大风产生之前,乌拉尔山东侧低频气旋与黄海上空低频反气旋同时出现并东移,之后衍生出华北低频反气旋与渤海低频气旋,这两个系统的加强促使华北上空偏北风加大,为山东大风的产生提供了可能。同时,华北地区经向风正距平逐渐被负距平所代替,是山东大风天气产生的又一先兆。
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| 关 键 词： | 山东大风 低频特征 振荡周期 经向传播 |
Analysis on low-frequency characteristics and mechanism of strong wind in Shandong |
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| Authors: | ZHENG Lin LIU Dongdong HE Pengcheng |
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| Institution: | (1. Key Laboratory for Meteorological Disaster Prevention and Mitigation of Shandong, Jinan 250031, China; 2. Jinan Meteorological Bureau, Jinan 250102, China; 3. Kenli Meteorological Bureau of Dongying, Kenli 257500, China) |
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| Abstract: | Based on the wind speed data from 122 national meteorological observation stations in Shandong and ERA-Interim reanalysis data provided by ECMWF, the strong winds and corresponding low-frequency atmospheric circulations in Shandong from September 2015 to September 2020 are analyzed by using wavelet analysis and band-pass filtering. The results are as follows. The frequency of strong winds in Shandong has increased in recent years with the highest frequency in spring and the lowest in autumn; the most frequent strong winds occur in the east of Shandong Peninsula and the least in the south of Shandong Province; the southerly winds are more frequent than northerly winds only in July for the whole year, while the northerly winds are dominant in other months. The frequency of strong winds in Shandong has significant low-frequency oscillation periods of 11-13 d and 20-23 d, among of which the oscillation period of 11-13 d is dominant in spring and the oscillation period of 20-23 d in autumn and winter, and the oscillation period in summer is not obvious. The evolution of oscillation period relates to the large-scale strong wind process, which occurs roughly at the peak of the oscillation wave. When the northerly strong winds are prevailing in spring, they are often accompanied by the propagation of meridional winds from north to south. In autumn, the meridional winds are propagated from south to north in the middle and upper troposphere on the north of 35°N and from north to south on the south of 35°N, while the propagation is opposite in the middle and lower troposphere. Before the occurrence of strong winds in spring in Shandong, the low-frequency cyclone over the east of the Ural Mountains and the low-frequency anticyclone over the Yellow Sea simultaneously appear and move eastward, and then the low-frequency anticyclone over North China and low-frequency cyclone over the Bohai Sea are derived. The strengthening of these two systems promotes the increase of the northerly winds over North China, which makes possible the occurrence of strong winds in Shandong. At the same time, the positive anomalies of meridional winds are gradually replaced by the negative anomalies over North China, which is another precursor of strong winds in Shandong. |
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| Keywords: | strong winds in Shandong low-frequency characteristics oscillation period meridional propagation |
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