主讲人简介：

  Prof.Oey obtained his Ph.D. from Princeton University. Now he is chair professor in National Central University in Taiwan, senior scientist in Princeton University,  editor of Journal of Geophysical Research – Oceans, guest editor of Ocean Dynamics, Lead Editor of Ocean Dynamics Special Issues for the International Workshop on Modeling the Ocean, co-developer and maintenance of the Princeton Ocean Model (POM), co-chair for IWMO - International Workshop on Modeling the Ocean: Dynamics, Syntheses & Prediction.

讲座简介：

  The North Pacific Subtropical Counter Current (STCC) has a weak eastward velocity near the surface, but the region is populated with eddies.  Studies have shown that the STCC is baroclinically unstable with a peak growth rate of 0.015 day-1 in March, and the ~60 day growth time has been used to explain the peak eddy kinetic energy (EKE) in May observed from satellite.  Here it is argued that this growth time from previously published normal-mode instability analyses is too slow.  Growth rates calculated from an initial-value problem without the normal-mode assumption are found to be 50~100% faster and at shorter wavelengths, due to the existence of (i) non-modal solutions, and (ii) sea-surface temperature front in the mixed layer in winter.  At interannual time scales, it is shown that due to rapid surface adjustments, the STCC geostrophic shear, hence also the instability growth, are approximately in phase with surface forcing, leading to EKE–modulation which peaks approximately 10 months later.  However, the EKE can only be partially explained by this mechanism of modulation by baroclinic instability.  It is suggested that the unexplained variance may be caused additionally by modulation of the EKE by dissipation.