长江干线航道强风的时空分布特征分析

Analysis of the Spatiotemporal Distribution Characteristics of Strong Winds in the Main Channel of the Yangtze River

关键词:  长江航道  气象风险因子  强风  时空分布  天气强迫

Key words:  Yangtze River channel  meteorological risk factor  strong wind  spatiotemporal distribution  weather forcing

摘要:

利用1991—2020年国家气象站逐日观测资料，对长江干线21个航段强风时空分布特征进行分析，并探讨了天气形势与下垫面环境等因素对其影响。从强风发生频次的年代变化来看，前10年（1991—1999年）呈下降趋势，中间阶段（2000—2011年）表现相对平稳，2012年之后则显著增加。大部航段强风事件集中发生在冬春两季，其中九江—安庆、芜湖—南京、泰州—太仓段为年频次高发航段；宜宾—泸州、泸州—重庆中西部为低发航段。强风（极大风）最大值常出现在宜宾—泸州、重庆、恩施、宜昌以及芜湖—太仓段。全航段强风的盛行风向为东北风和北风，其中春、秋、冬季强风以东北风和北风为主，夏季风向特征不明显。强风事件发生原因主要分为两类：一类是受特殊地形及水陆分布影响而多发的地理特征性大风，如川渝航段、鄂西航段及皖南航段等；另一类是受天气系统强迫而产生的系统性大风，具有明显季节特征，主要分为冷锋后偏北大风及中小尺度对流系统引发的雷暴大风。前者多出现在冬春两季，主要受冷锋及气旋系统影响，以东北风和北风为主；后者常发生在每年的3—9月，具有突发性、局地性和极端性特征。此外，在7—9月，长江干线中东部航段还易受热带气旋（台风）东移北上影响，易发生大风。研究结果为长江沿线海事相关部门有效规避气象风灾提供了参考依据。

Abstract:

Using daily observation data from the National Meteorological Station from 1991 to 2020, this study analyzes the spatiotemporal distribution characteristics of strong winds in 21 sections of the Yangtze River mainline, and explores the influence of weather conditions, natural geographical environment, and other factors on them. From the perspective of the temporal changes in the frequency of strong winds, a downward trend was observed during the first decade (1991-1999), followed by a relatively stable period (2000-2011), and a significant increase after 2012. Most strong wind events occur in the winter and spring, among which the Jiujiang-Anqing, Wuhu-Nanjing, and Taizhou-Taicang sections exhibit the highest annual frequencies, whereas the Yibin-Luzhou and central-western Luzhou-Chongqing are low-frequency routes. The strong wind (maximum wind) maximum value often occurs in the Yibin-Luzhou, Chongqing, Enshi, Yichang, and Wuhu-Taicang sections. The prevailing strong wind directions throughout the entire sections are northeasterly and northerly. Northeast wind and north wind dominating in spring, autumn, and winter, while no distinct prevailing wind direction is observed in summer. The causes of strong wind events can be mainly divided into two categories. One is geographic characteristic winds that are frequently affected by special terrain and land-water distribution, such as those in the Sichuan-Chongqing, western Hubei, and southern Anhui sections. The second category consists of systemically forced strong winds driven by weather systems. These exhibit pronounced seasonal characteristics and are mainly divided into northerly gales after cold fronts and thunderstorm-induced winds caused by mesoscale and microscale convective systems. The former mostly occurs in winter and spring, mainly affected by cold fronts and cyclone systems, with northeast and north winds as the main ones; The latter often occurs from March to September each year, characterized by its suddenness, localization, and extreme intensity. In addition, the central and eastern sections of the Yangtze River mainline from July to September are highly susceptible to strong winds induced by tropical cyclones (typhoons) moving eastward and northward,. The research results provide a basis for maritime departments along the Yangtze River to effectively avoid meteorological wind disasters.