越赤道气流不同波长分量对台风Megi(2010)路径偏折的影响与模拟检验

Impact of Different Scale Component of Cross-equatorial Flow on the Track Deflection of Typhoon Megi(2010)and Its Simulation Test

基于NCEP再分析资料和NOAA高分辨率海温资料,采用空间傅里叶滤波法,分析了台风Megi(2010)路径北折过程中越赤道气流强度随时间的变化,以及其不同波长分量对台风移动路径转折的影响,利用谱逼近方案的数值模拟对分析结果进行验证。结果表明,加里曼丹岛附近越赤道气流突然增强北涌对台风移动路径北折具有重要影响。经纬向波长为500km以上的低层风场分量的环流结构能明显反映出加里曼丹岛附近越赤道气流中的中尺度反气旋系统。模拟试验结果与分析结果一致,即环境风场的中尺度分量是影响台风路径北折的重要因子,其中经纬向波长为500 km以上风场分量体现了加里曼丹岛附近越赤道气流风场结构中的中尺度反气旋系统对台风路径的影响,因此,其模拟路径与观测路径最为接近。

Based on NCEP reanalysis data and NOAA high resolution SST data,the temporal evolution of cross-equatorial flow strength during the north deflection period of Typhoon Megi（2010）were discussed by using Spatial Fourier filter.The results showed that the northward strengthening of cross-equatorial flow around Kalimantan Island played an important role in the north deflection of typhoon track.The meso-scale anticyclone in the Kalimantan cross-equatorial flow can be reflected obviously by the circulation structure of lower wind component with zonal and meridional wavelength larger than500 km.The meso-scale components in the environmental wind field had an important impact on the north deflection of Megi track,and the wind component with zonal and meridional wavelength lager than 500 km reflected the impact of meso-scale anticyclone in the Kalimantan cross-equatorial flow on the typhoon track,thus the simulation was in good agreement with the observation.