Characterizing circulation pattern in marginal sea and diagnosing its complex forcing mechanism between intrinsic flow-topography interaction and extrinsic flux from adjacent open seas remain challenge. Using observations, numerical modeling and novel Stoke-based layer-integrated vorticity equation (LIVE) dynamics in the typical marginal Japan Sea (JS), we, for the first time, discovered alternating cyclonic, anti-cyclonic, and cyclonic circulation in the upper (0-150 m), middle (150-250 m), and bottom (>250 m) layers of the JS, respectively. We diagnosed that besides vorticity input from wind stress curl in the upper layer, the lateral planetary vorticity fluxes from inflow/outflow through the straits surrounding the JS lead to vortex stretching in all layers and extrinsically control the structure of the layered circulation. The joint effects of baroclinicity and relief (JEBAR) arising from flow–topography interaction is an intrinsic dynamic response to the extrinsic forcing and dynamically shapes the layered circulation. Based on Stokes circulation theorem, this study characterizes the layered circulation pattern and develops LIVE dynamics to effectively identify intrinsic and extrinsic forcing mechanisms for the layered circulation in the JS and other marginal seas.

Japan Sea,rotating layered circulation,vorticity dynamics