Dynamics of a 3-dimensional, baroclinic, headland eddy

Wave, current, and temperature measurements from the north side of Cape Rodney, northeastern New Zealand, over a 6-week field programme, reveal the detailed internal dynamics of a baroclinic eddy. The measurements include water levels, currents, and water temperatures through the water column and seabed descriptions. A detailed calibration of a 3-dimensional numerical model leads to further examination of the flow and density structure within the eddy, in plan and cross-section. The eddy stretches c. 5 km along the northern side of the headland and is of the order of 1.5-2.0 km wide. The eddy currents are strongest near the bed and against the coast. The eddy is characteristically complex and vertical eddies readily form in parts of the water column during different phases of the tide, although these internal eddies rarely penetrate through the full depth. The dynamics near the surface and near the bed are significantly different and the structure of the eddy is often partitioned vertically and is strongly affected by wind.