龙卷发生环境与机理及灾情调查研究进展

Advances in research on environments,formation mechanisms,and damage survey of tornadoes

  • 摘要: 龙卷致灾性强、社会关注度高。文中回顾了龙卷机理研究、强度等级和灾害现场调查技术进展,给出了龙卷涡旋形成机制、现场调查需要注意的方面和强度估计存在的难点等,对未来进行了展望。通常认为中气旋龙卷的有利环境条件已非常明确,但不同环流背景下并不尽然,如冷涡背景下的大气低层湿度条件必要性、台风龙卷的对流有效位能作用等,以及龙卷爆发事件同一般龙卷事件的环境条件是否存在差异还有待深入研究。中气旋龙卷形成的关键是低层中气旋的形成,近地表涡旋小块的产生、组织和增强以及地表摩擦作用使得涡旋发展为具有涡旋边界层和拐角流区域的龙卷。地势分布对龙卷影响非常复杂;通常龙卷上坡会减弱、下坡会加强。不同龙卷的消亡机制可能不同。F等级、EF等级和T等级为常用的龙卷强度等级,目前得到广泛应用的是EF等级,中国国家标准的龙卷风强度等级与EF等级有明确对应关系。中国的风灾现场调查技术方法已发展较为成熟,获得了大量龙卷灾害调查数据;但综合应用多源精细遥感资料的龙卷灾害评估技术还有待进一步发展。龙卷的致灾机制非常复杂,强度估计有很大的不确定性。龙卷观测、现场调查、机理研究和预报、预警能力的精细度需要持续提升。

     

    Abstract: Tornado disasters are intense and have been attracting significant social attention. This article reviews recent research progress on tornado mechanisms, intensity scales, and damage survey methodologies. It examines key aspects such asprocesses of tornadic vortex formation and dissipation, challenges in field surveys and intensity estimation, and so on,and provides outlool for future research. While the favorable environmental conditions for mesocyclone tornadoes are well documented, several critical questions remain unresolved: The role of low-level atmospheric humidity under cold vortex conditions, the influence of convective available potential energy in tropical cyclone tornadoes, and the environmental prerequisites for tornado outbreak events. The formation of mesocyclone tornadoes involves multiple stages: Development of mesocyclones, generation and organization of near-surface vortex patches, subsequent intensification, and the critical influence of surface friction leading to the development of tornado vortex boundary layers and corner flow regions. Topography exerts complex effects on tornado behavior, typically causing weakening during uphill movement and intensification during descent. Tornado dissipation mechanisms vary, with any disruption to sustaining factors potentially leading to vortex demise. Common tornado intensity scales include the Fujita (F), Enhanced Fujita (EF), and TORRO (T) scales. The T-scale features the most detailed categorization (11 levels), while the EF-scale remains the most widely adopted standard internationally. China’s national tornado intensity classification system aligns directly with the EF-scale. Significant advancements have been made in severe wind damage survey methods and procedures, with extensive tornado case data now available in China. However, the complex disaster mechanisms of tornadoes introduce substantial uncertainty in intensity assessment. Continued improvements are needed in high-resolution observations, damage survey techniques, physical mechanism studies, and forecasting/warning capabilities to enhance tornado preparedness and mitigation efforts.

     

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