Advances in Research on Environments, Formation Mechanism and Damage Survey of Tornadoes

Tornado disasters are intense and has been attracting high social attention. This article provides an overview of recent research on tornado mechanisms, tornado intensity classifications, and advances in damage surveys of China. It highlights the formation mechanism of tornadic vortex, difficult aspects of field surveys and challenges in estimating tornado intensity, and presents a perspective on future research. The favorable environmental conditions for mesocyclone tornadoes are well established, yet the necessity of low-level atmospheric humidity conditions under cold vortex settings, the role of convective available potential energy in tropical cyclone tornadoes, and the favorable environmental conditions for tornado outbreak events still require further studies. The formation of mesocyclone tornadoes is pivotal, involving the development of low-level mesocyclones, the generation and organization of vortex patches, their enhancement, and the influence of surface friction that leads to the development of tornadoes with vortex boundary layers and corner flow regions. The topographic influence on tornadoes is very complex. In general, tornadoes weaken when moving uphill and intensify when descending downhill. The dissipation mechanism of different tornadoes may be different, and any factor that is not conducive to maintenance of tornadoes may cause their demise. Common tornado intensity classifications include F-scale, EF-scale, and T-scale; the T-scale has the most levels, with 11 categories; the EF-scale is the most widely accepted; and the China national standard of tornado intensity classification definitely corresponds to the EF-scale. The methods and steps for damage surveys of severe wind disasters have significantly developed, and a substantial amount of tornado survey data has been collected in China. The disaster-causing mechanisms of tornadoes are intricate, and there is considerable uncertainty in intensity rating. There are needs for continuous improvement in fine observations and damage surveys, mechanism studies, and forecasting and warning capabilities for tornadoes.