Generation and propagation of 21-day bottom pressure variability driven by wind stress curl in the East China Sea

Abstract

Between June 2015 and June 2017, two pressure-recording inverted echo sounders (PIESs) and five current and pressure-recording inverted echo sounders (CPIESs) deployed along a section across the Kerama Gap acquired a dataset of ocean bottom pressure records in which there was significant 21-day variability (P-bot21). TheP(bot21), which was particularly strong from July-December 2016, was coherent with wind stress curl (WSC) on the continental shelf of the East China Sea (ECS) with a squared coherence of 0.65 for a 3-day time lag. A barotropic ocean model demonstrated the generation, propagation, and dissipation ofP(bot21). The modeled results show that theP(bot21)driven by coastal ocean WSC in the ECS propagated toward the Ryukyu Island Chain (RIC), while deep ocean WSC could not induce such variability. On the continental shelf, theP(bot21)was generated nearly synchronously with the WSC from the coastline to the southeast but dissipated within a few days due to the effect of bottom friction. The detection ofP(bot21)by the moored array was dependent on the 21-day WSC patterns on the continental shelf. TheP(bot21)driven southeast of the Changjiang Estuary by the WSC was detected while the Pb(ot21)generated northeast of the Changjiang Estuary was not.