Program
 
General Session 1: Physical oceanic processes: Dynamics and physical-biological-biogeochemical interactions
 

 
 
1420
Variability of the Pacific North Equatorial Current and its implications on Japanese eel (Anguilla japonica) larval migration
Monday 9th @ 1420-1435
Conference Hall
Huijie Xue* , South China Sea Institute of Oceanology; University of Maine
Ango C. Hsu, University of Maine
Zhichun Zhang, South China Sea Institute of Oceanology
Fei Chai, 2nd Institute of Oceanography, SOA
Presenter Email: huijiexue@scsio.ac.cn
The zonal velocity produced by a Regional Ocean Modeling System (ROMS) based Pacific Ocean circulation model was validated against in situ measurements along the 137∼E longitude. The Pacific model successfully reproduced the position and the shape of the North Equatorial Current (NEC) as well as the latitude of maximum surface velocity in the NEC region (8 每 17∼N). The flow field produced by the Pacific model was then used to conduct numerical Lagrangian experiments, in which passive particles were released in the known Japanese eel spawning range (142.5∼E, 12.5 每 17∼N), and the effects of NEC strength and bifurcation latitude on the particle advection in the northwest Pacific were studied. Our results suggest that, in the 20-year period (1993每2012), variability of the currents alone can cause one-order-of-magnitude interannual variability in the Kuroshio Entrance (KE), the percentage of particles entering the Kuroshio, which ranges from 43% in 1997 to 6% in 2012. The yearly-averaged KE is not sensitive to the NEC bifurcation latitude. Instead, it is controlled by the average zonal velocity of a fixed domain (125 每 143∼E, 13.5 每 17∼N) and related to a recently-developed climate index, the Philippines-Taiwan Oscillation (PTO). During the positive phase of PTO, the zonal velocity in the domain hence the yearly-averaged KE increase, and the opposite is true. Considering only the trajectories, diel vertical migrations (DVM) in the top 400 m do not significantly affect Japanese eel larval transport, as incorporating DVM schemes does not increase the KE.