2012年“苏拉”和“达维”双台风影响的近海风暴潮过程

作为影响我国沿海的主要自然灾害之一,台风风暴潮的产生和影响机制与防灾减灾息息相关。双台风引起的风暴潮因台风强度、路径等相对关系复杂多变,目前双台风相互作用下的风暴潮研究还不充分。采用参数化台风模型对2012年典型双台风"苏拉"和"达维"的风场、气压场过程进行了模拟与融合,并采用ELCIRC模型对双台风作用下的风暴潮过程进行了模拟。引入单台风单独作用的假设算例,探讨了双台风之间对增水、流场的相互影响和影响区域。研究结果表明,虽然两个台风登陆强度相当,但台风"达维"在海州湾海域引起的增水要远大于"苏拉"在台湾、福建海域引起的增水。风暴潮引起的增水及流速变化与台风在海表的风应力密切相关,较大变化幅值分布在台风行进路径的右侧。与台风单独作用时相比,台风"苏拉"与"达维"引起的风暴潮增水与流速变化在两者相互作用下均有所削弱,其中"苏拉"引起的风暴潮受到的影响更大。双台风风暴潮之间的非线性效应在不同区域的强度存在差异,在台风"苏拉"主要影响区域内非线性效应较强,其他区域则相对较弱。以上结果表明产生风暴潮较弱的台风一方对气象环境敏感性更高,风暴潮的响应更显著。

Storm surges influenced by binary Typhoons of Saola and Damrey in 2012

Typhoon-induced storm surge is one of the major natural hazards in the coastal China. Study on generation mechanisms and impact factors of storm surge provides important knowledge for coastal hazard defense and mitigation. However, the storm surge induced by binary typhoons was not fully studied yet because of the complexity of their comparative relationship such as typhoon intensity and track. In the present study, parametric vortex model is used to reproduce the meteorological processes associated with a representative binary typhoon event, Typhoon Saola and Typhoon Damreyin 2012. The generated wind fields and atmospheric pressure fields of these binary typhoons are further coupled in the tide-surge model ELCIRC, for simulating storm-induced surface elevation and current velocities. Scenarios affected by Saola and Damrey respectively alone are also designed to examine the storm surge patterns influenced by their co-interaction and to quantify their separate impacts on each other. The results demonstrate that the storm surge induced by Typhoon Damrey in Haizhou Bay is much larger than that by Typhoon Saola in Taiwan and Fujian coasts, although these two typhoons have equivalent landfalling intensities. Larger storm surge and storm-induced flow velocity are produced at the right-hand side of typhoon moving tracks,which indicates that local wind stresses at sea surface play a major role in generating surges. Compared with scenarios that separate typhoon occur alone, the interactions between Typhoon Saola and Damrey lead to decreased surge and storm-induced flow velocity by these binary typhoons, and the impacts of Damrey on Saola is stronger. The decrements of storm surge influenced by each of these binary typhoons differ spatially with nonlinear effect. This nonlinear effect is strong in the coastal regions mainly affected by Typhoon Saola, but weak in other regions. The results indicate that the typhoon which induced weaker surge, tend to be more sensitive to surrounding weather conditions and to respond more strongly in modulating surge patterns.