Sea level variations responding to the atmospheric and oceanic processes in the northwestern Pacific Ocean

Abstract:

Regional sea level was exhibited the ubiquitous interannual variations geographically in the China Seas (including the East China Sea and the South China Sea) and the northwestern Pacific Ocean. The atmospheric and oceanic contributions to the variability were investigated by the tide gauges observation, reconstructed sea level combined with the altimetry data. Based on the last 50 years data, sea level variations responded to the local and general atmospheric circulation in the perspective of barotropic and baroclinic modes. Our study had shown that the dynamic process resulted from the atmosphere circulation, especially the wind field anomaly, could explain the discrepancy of sea level. Compared to the local ekman pumping effect, the remote Rossby wave, originated by wind field anomaly, accounted for nearly two third of the atmospheric influence. Sea level was manifested the correlation at 5-8 years lag with the basin mean wind stress curl anomalies. The typical oceanic processes associated with the regional sea level variation were described as the thermosteric effect and water mass changes in this study. Migration and redistribution of water mass induced by ocean current acted as the comparable contributor, according to the simultaneous thermosteric effect. Ocean transports of west boundary current varied robustly, which indicated the variability of the north Pacific subtropical gyre related to PDO and ENSO, and established the dynamic background of sea level variations in NW Pacific.