北太平洋中尺度涡季节和年际变化的统计分析

摘要

Surface anomalous geostrophic currents from January 1 993 to October 2014,which are derived from altimetry dataset,and a geometry-based eddy detection method are used to detect and track the me-soscale eddies in the north Pacific Ocean.Statistics shows that the distributions of eddy radius,propaga-tion distance and propagation speed can be well fit with logarithm normal distribution function.Analysis further demonstrates that the number of the eddies generated is maximum in the winter while minimum in the summer.The major difference in distribution of the eddies in winter and summer is in the region 15°-35°N.In addition,the number of eddies shows remarkable interannual variation,in which each season con-tributes basically equally to the variability.In both seasonal and interannual variations,the anomalous number of eddies is negatively correlated with the SST anomaly in the north Pacific Ocean.This is proba-bly because anomalous SST changes the stratification of the upper layer of the ocean and thus affects the generation of eddies—this mechanism needs to be further verified in future study.%依据1993-01-2014-10由卫星高度计资料导出的地转流异常场数据，用几何方法探测识别并追踪了北太平洋的中尺度涡，统计了涡旋的半径、移动距离和移动速率，发现它们近似服从对数正态分布。进一步的分析发现，北太平洋涡旋生成数量存在着显著的季节变化：在冬季涡旋生成的数量最多而夏季生成的数量最少；夏季与冬季相比，涡旋生成数量减少的区域主要集中在15°~35°N。此外，北太平洋涡旋生成数量还存在着显著的年际变化；各个季节对全年变化的方差贡献量值相当。不论是季节变化还是年际变化，涡旋生成数量的变化与 SST 的变化均是反相，这是因为 SST 变化改变了上层海洋的层结强度进而影响了涡旋的生成，但该物理机制还需要进一步的分析和验证。