Subtidal temperature variability in stratified shelf water off the mid-east coast of Korea

A wind-forced coastal trapped wave (CTW) model is applied to examine subtidal (period of a few days to weeks) temperature variability in stratified waters off the mid-east coast of Korea, and mechanisms underlying the temporal structure modified from the model prediction are discussed. Model-predicted, depth-averaged temperature is significantly correlated with observed temperature (TOBS) and the correlation coefficients increase as including remote wind forcing. Modeled phase speeds (4.6–5.9 and 9.5–10.3 m/s off northern and southern coasts) are consistent with speeds of sea level propagation observed along the coast (6.1 and 10.4 m/s respectively). Our results suggest that the wind-forced CTW model reasonably reproduces most (though not all) subtidal temperature variability off the coast within a semi-enclosed deep basin as were often cases for open-sea shelves. However, TOBS is hardly explained solely by the model particularly when horizontal nonlinear advection becomes significant. Abrupt changes in water properties caused by sudden downwelling and successive amplification of diurnal oscillations are suggested as (nonlinear and/or turbulent) mechanisms modifying the temporal structure of temperature beyond the CTW dynamics.