Predictability of Kuroshio Current Intrusions into the East China Sea.

We use a combination of observations and two fine resolution ocean models to understand the predictability of Kuroshio Current intrusions onto the East China Sea Shelf. The simulations were evaluated for their potential to provide lateral boundary conditions to a real-time regional prediction system whose function is to depict both physical and acoustical properties over the North Taiwan Shelf. Volume transport across the East Taiwan Channel (ETC) as measured by the WOCE PCM-1 moored current meter array was correlated with sea surface height anomaly for the period September 1994 through May 1996. Low transport events were found to be correlated with low sea level off the east coast of Taiwan and surface drifting buoys passing through the ETC were found to encroach the 200 m isobath to the north of Taiwan more often during low rather than during high transport (high sea level) events. We use two models to predict these intrusions: one is the 0.1° global Parallel Ocean Program (POP) and the other is 1/12° global Hybrid Coordinate Ocean Model (HYCOM). The latter model includes the Navy Coupled Ocean Data Assimilation (NCODA) system. Both models are forced with synoptic atmospheric fluxes. Lagrangian particles are released off the southeast coast of Taiwan during high and low ETC transport events. Both models show intrusive behavior during low transport events however those in HYCOM are more realistic in terms of extent and location. Analysis of the equivalent non-assimilative HYCOM simulation will be presented to better understand the role of data assimilation and the vertical coordinate system on the characteristics of these intrusions.