Meridional deflection of global eddy propagation derived from tandem altimetry: Mechanism and implication

作     者：Ge CHEN Xiaoyan CHEN 

作者机构：Frontiers Science Center for Deep Ocean Multispheres and Earth SystemSchool of Marine TechnologyOcean University of ChinaQindao 266100China Laboratory for Regional Oceanography and Numerical ModelingLaoshan LaboratoryQindao 266237China 

出 版 物：《Science China Earth Sciences》 (中国科学（地球科学英文版）)

年 卷 期：2024年第67卷第3期

页      面：811-825页

核心收录：

学科分类：07[理学] 070601[理学-气象学] 0708[理学-地球物理学] 0706[理学-大气科学] 

基　　金：supported by the National Natural Science Foundation of China(Grant No.42030406) the Science and Technology Innovation Fund of Laoshan Laboratory(Grant No.LSKJ202204301) the International Research Center of Big Data for Sustainable Development Goals(Grant No.CBAS2022GSP01) 

主　　题：Mesoscale eddies Eddy propagation Eddy meridional deflection Satellite observation Geostrophic adjustment 

摘      要：A common view on meridional deflection of eddy propagation is poleward for cyclones and equatorward for anticyclones. This widely accepted polarity-sensitive pattern has been increasingly undermined given that it is systematically violated on both zonal and regional scales as recently reported. Here, we approach the problem by exploring these violations in terms of eddy effects of spatiotemporal geostrophy, thermal fading, and flow dragging, yielding the following main conclusions.(1) The polarity-dependent deflection discrepancy is a pseudo feature resulting from a biased fit to the normalized eddy tracks which are spatially asymmetric(though azimuthally symmetric) between the two signs;Instead, the primary pattern of eddy deflection appears to be geographically correlated and polarity independent.(2) Geostrophic adjustment plays a critical role in defining the meridional movement of an eddy. Specifically, a consistent poleward(equatorward) trajectory bending of spatially(temporally) ageostrophic eddies is observed irrespective of their polarity.(3) The mechanism of eddy deflection is also determined by its zonal propagation direction. Westward propagating eddies are substantially affected by thermal fading, while opposite ones by flow dragging. A realistic and comprehensive understanding of eddy deflection mechanisms serves as a significant contribution to the prediction of eddy trajectory, and the protection of ocean environment.