Locations of Moorings and Influence of their data near the Mien Hwa Canyon

Pierre F.J. Lermusiaux & Patrick J. Haley Jr.

This page presents the results of simulations of the advection of passive tracers North of Taiwan. The tracers are continually introduced at set of possible mooring locations and then advected/mixed by the dynamical ocean model equations (without wind or tidal forcing). A goal of these simulations is to estimate the influence of measurements made at those locations. The results of 2 different experiments are presented:

  1. No particular value was specified for the initial transport between Taiwan and mainland China.
  2. An initial northward transport of 1 Sv was imposed between Taiwan and mainland China (of course, after t0, this transport evolves).

Results for
Free Transport 1 Sv N Transport
by mooring group by depth by mooring group by depth

We selected a set of 12 possible locations, all around the Mien Hwa Canyon and North Mien Hwa Canyons, and shallower than 600m (see plots below). We separated the moorings in three groups (for each of the two transport cases). The first group are 4 moorings on the southern side of the Mien Hwa Canyon, the second group are 4 mooring on the northern side of the Mien Hwa Canyon and the third group are 4 moorings that are north of the Mien Hwa Canyon. For each of these 3 groups and initial conditions, a tracer simulation is carried out. Tracers are continually introduced at the 4 candidate mooring locations and advected/eddy-diffused by the simulated ocean dynamics. Without entering details, results indicate that a good location for a mooring is at the Mien Hwa Canyon, perhaps on its northern side. This is where the shelfward currents are often strong. Upwelling occurs and the tracers are advected/eddy-diffused in the cold dome region and beyond.

This work is part of our preparation for the DRI-QPE (ONR-sponsored), in response to a request by Dr. Ren-Chieh Lien from U. Washington, APL. A more comprehensive overview of our modeling research is given in the Modeling Group presentation.

The mooring position that was utimately chosen is given below.

Mooring Locations with 150m & 600m isobaths
Canyon South Canyon North Northern
25.2481N, 122.2714E25.4779N, 122.2552E25.5221N, 122.5305E
25.3070N, 122.3167E25.4661N, 122.3427E25.6017N, 122.5435E
25.3483N, 122.2520E25.4249N, 122.4074E25.6399N, 122.6212E
25.4190N, 122.2099E25.4632N, 122.4851E25.6989N, 122.6665E

Choice. After several discussions with Dr. Ren-Chieh Lien, the final location of the mooring position was chosen to be on the northern wall of the Mien Hwa Canyon, at 122.4E and 25.33N (at a depth close to 600m). This location on the northern side of the Canyon fits our studies above. The small position difference is due to the better bathymetry of the National Center for Ocean Research (NCOR) of Taiwan (which was not available for our simulations).