THE INFLUENCE OF OCEAN BACKGROUND VORTICITY ON NEAR-INERTIAL WAVES INDUCED BY TYPHOON CONSON
Near-inertial waves(NIWs)are a type of internal waves,and which are ubiquitous in the global ocean.The propagation and dissipation of NIWs are affected by the background vorticity.Based on the hybrid coordinate ocean model(HYCOM)reanalysis data,we studied the different effects of positive and negative background vorticities on the NIWs induced by Typhoon Conson in the South China Sea.Results show that the negative vorticity can capture and promote the propagation of near-inertial energy to the deep ocean(exceeding 1 200 m depth).However,the positive vorticity inhibits the downward propagation of near-inertial energy,making it concentrated mainly within the upper 500 m.Strong near-inertial energy in the negative vorticity region can last for more than 10 days,while that in the positive vorticity region only lasts only about a week.The NIWs in the negative vorticity region are dominated by the second and third modes,while those in the positive vorticity region are dominated by the first and second modes.As a result,the shear caused by NIWs in the negative vorticity region is 1～2 orders of magnitude stronger than that in the positive vorticity region at 500～1 000 m depth.The simulation results of the ray-tracing model show that the NIWs are reflected at the edge of the negative vorticity region and then are captured by the negative vorticity region.In contrast,the NIWs in the positive vorticity region tend to accelerate away from the source.These results further indicate that the negative background vorticity enhances the vertical propagation of near-inertial energy,while the positive vorticity promotes the horizontal propagation of near-inertial energy.
ocean background vorticitynear-inertial waveshybrid coordinate ocean model reanalysis dataray-tracing model
万方数据
维普
