THE LOCAL AND NONLOCAL RESPONSE OF CONCEPTION BAY TO WIND FORCING

In this paper the response of Conception Bay to wind forcing is discus sed. Current meter and thermistor chain observations are analyzed and compared with output from a reduced-gravity numerical model. The model incorporates realistic coastal geometry and is driven by wind stress calculated from observed winds. Moorings were deployed in the bay duri ng 1989 and 1990. In 1990 the moorings were placed within the coastal waveguide around the head of the bay and show that southwesterly winds generate an upwelling event on the western side that moves around the head of the bay and is suggestive of Kelvin wave propagation. Data an alysis shows that the thermocline response is strongly coherent betwee n each mooring at periods of 2-10 days, and winds measured at a nearby station are found to be strongly coherent with the observed temperatu re fluctuations. Two versions of the reduced-gravity model are applied -one models Conception Bay alone and ignores ''upstream'' influences a nd another includes neighboring Trinity Bay, located to the northwest and ''upstream'' in the sense of Kelvin wave propagation. The local mo del does reasonably well at reproducing the observed movement of the t hermocline but underestimates its amplitude. The nonlocal model, which includes the neighboring bay, does much better at simulating the obse rvations, including the amplitude of the response, and also the upper- layer currents. The comparisons clearly show the importance of nonloca l effects.