Eddy Structure Characteristics And Their Energy Transport In The Yellow-East Sea

First of all, due to the frequent eddy activities near the Kuroshio, sea surface height anomaly altimeter data from 1993 to 2010 are used to study the number of eddies and their size, lifetime, relative vorticity and other characteristics, even the generation mechanism, based on a velocity geometry-based automated eddy detection scheme. There are 7716 eddies in the Yellow-East Sea (with lifetime equal to or larger than 4 weeks), including 3790 cyclonic eddies and 3926 anticyclonic eddies. Mean lifetime is 7 weeks, with an average radius of 55 kilometers and the average relative vorticity ±0.1. No significant difference can be found between cyclonic and anticyclonic eddies. Eddy kinetic energy has greater values east of the Kuroshio and smaller ones west. Cyclonic eddies are generated west of the Kuroshio and anticyclonic eddies east, symmetrically. Kuroshio is one of the main eddy generation mechanism, and the cyclonic eddy generation is very consistent to time series of Kuroshio transport, but due to the terrain and distribution from open sea, anticyclonic eddies are also subject to other factors.To explore the 3-D structure and energy transport of eddies, especially a more sophisticated spacial and temporal analysis, we focus on the seasonal characteristics and typical eddy cases through diagnosis and numerical simulation in the Yellow Sea. The analysis of the two types of thermal construction and energy transport characteristics on two types of eddies shows that:in the Yellow Sea, cold or warm center does not exist on the sea surface for both cyclonic and anticyclonic eddies, which are presented at 25 meters depth. Cyclonic eddy energy divergents in the horizontal direction, presenting an asymmetry eddy energy transport in vertical direction. Eddy energy transfers deeper where the flow is strong. However, anticyclone eddy energy convergents in the horiziontal direction, and uniforms in the vertical direction, which is much less than that of cyclonic eddy. Numerical simulation on the temporal and spatial structure of eddy energy using FVCOM in the Yellow Sea shows that cyclonic eddies are larger in the scope, intensity and depth than anticyclonic ones. Their momentum transfers deeper and faster, maintaining much longer. For the cyclone eddy, the energy transmission in the central part is stronger and faster than that of the annular side, with an asymmetric structure. Due to the symmetry of energy and weak current, the influence of topography and water depth on anticyclonic eddies is also significant.