海水运动感应磁场对台风的响应特性分析

Response Characteristic Analysis of Seawater Motion-Induced Magnetic Field to Typhoon

海水运动感应磁场是海洋电磁数据处理和解释的重要环境背景场。为了解和认识极端天气下海水运动感应磁场的变化特性,本文对台风条件下海水运动感应磁场展开研究。将高精度的区域耦合模式(Coupled Ocean-Atmosphere-Wave-Sediment Transport Modeling System, COAWST)应用于海水运动感应磁场计算中,以台风“格美”(编号201220)为例,估算海水运动感应磁场,探讨台风条件下感应磁场的时空变化特征,定量评估台风对感应磁场的影响范围。研究表明,该台风引起的感应磁场最大达0.8 nT,水平影响范围约200~500 km;台风对感应磁场的影响具有滞后性和持续性;台风影响下海水电导率发生明显变化,对感应磁场具有重要贡献。

Magnetic fields induced by seawater motions are important environmental background fields for marine electromagnetic data processing and interpretation. Previous studies have revealed that changes in the induced magnetic field of seawater movement are mostly based on the calm sea state, while few have focused on the variations under the extreme weather. In this paper, we studied the seawater motion-induced magnetic field under typhoon conditions. Here, we use a high-precision regional coupled model(Coupled Ocean-Atmosphere-Wave-Sediment Transport modeling system, COAWST) to calculate the motion-induced magnetic field. Taking the typhoon Gaemi(201220) as an example, we simulate the typhoon using the COAWST model, and estimate the motion-induced magnetic fields basing on the model outputs. The Spatial-temporal variations of the induced magnetic fields under typhoon conditions are discussed, and the influence range of this typhoon on the induced magnetic field is quantitatively evaluated. The results show that the maximum induced magnetic field caused by the typhoon is 0.8 nT, and the horizontal influence range is about 200~500 km;the influence of typhoon on the induced magnetic field is lagged and durative;the seawater conductivity changes significantly during the typhoon passing, which plays an important role on the induced magnetic field.