Coastal-Trapped Waves in the East China Sea Observed by a Mooring Array in Winter 2006

Abstract

Abstract Using five mooring array observations in the coastal water of the East China Sea (ECS) in winter 2006, the authors identify three kinds of low-frequency waves using the ensemble empirical mode decomposition (EEMD) method. The analysis indicates that the periods of the waves varied from 2 to 10 days, which are consistent with coastal-trapped wave (CTW) modes: the Kelvin wave (KW) mode, the first shelf wave (SW1) mode, and the second shelf wave (SW2) mode. An analytical model is established and the dispersion relation of the waves from the analytical method agrees well with the observations. The wind-forced, coastal-trapped wave theory is then applied. The calculation shows that over a wide shelf, the forcing term of wind stress curl plays an important role in shaping the CTW. Numerical solutions reproduce the sea level variation and the alongshore current. The results show that the sea level variation mainly resulted from the KW mode, but the alongshore current resulted from both the KW and SW1 modes.