Effects of Tropical Cyclone on Kuroshio and the Adjacent Shelf-Slope Waters

Effects of tropical cyclones (TCs) on Kuroshio and the adjacent shelf-slope waters are investigated using several independent satellite observations and a three-dimensional primitive equation ocean model. Model simulation suggested that a cyclonic eddy triggered by Nari had occurred in regions north of Kuroshio. As a result, the cold SST patch was only visible to the north of the Kuroshio axis. The cyclonic circulation penetrated much deeper for a slowly-moving storm, regardless of the typhoon intensity. Near-inertial frequency oscillations after typhoon departure were simulated by the model in terms of the vertical displacement of isotherms. The SST cooling caused by upwelling and vertical mixing is effective in cooling the upper ocean several days after the storm had passed. At certain locations, surface chlorophyll concentrations increased significantly after Nari's departure. Upwelling and mixing bring nutrient-rich subsurface water to the sea surface, causing enhancement of phytoplankton bloom.