Exchange through a Barrier Island Inlet: Additional Evidence of Upwelling off the Northeast Coast of North Carolina

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  • 1 Department of Geosciences and Center for Marine and Coastal Studies, North Carolina State University, Raleigh 27607
  • | 2 Skidaway Institute of Oceanography, Savannah, Ga. 31406
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Abstract

During the period 20 June-2 July 1973, hydrographic data were collected at Oregon Inlet, N. C. An examination of the water temperature time-history record at three stations in and near the inlet show 1) that in two periods with predominately southerly winds, the temperature fluctuated in the range from 13.7° to 27.5°C with an apparent tidal periodicity; 2) that for nearly 48 h between these two periods and with northeasterly winds, a nearly constant temperature of 22.0° to 22.5°C was maintained in spite of normal tidal fluctuations; and 3) this constant temperature period is bracketed by two 24 h transitional periods that are initiated almost coincidently with wind directional changes. It appears that the sequence and relationship of these wind and water temperature data may be explained by and provide additional evidence and documentation of wind-induced upwelling along the northeastern North Carolina coast previously reported by Wells and Gray (1960), Carter, Pritchard and Carpenter (1966) and Boicourt (1973). Indeed, an important conclusion that can be drawn from this sequence and relationship of data is that temperature, salinity and current velocity records in and near a barrier island inlet can furnish much information about the exchange and mixing processes on the adjacent continental shelf, especially when there are large differences in temperature and salinity between the sound and shelf waters.

Abstract

During the period 20 June-2 July 1973, hydrographic data were collected at Oregon Inlet, N. C. An examination of the water temperature time-history record at three stations in and near the inlet show 1) that in two periods with predominately southerly winds, the temperature fluctuated in the range from 13.7° to 27.5°C with an apparent tidal periodicity; 2) that for nearly 48 h between these two periods and with northeasterly winds, a nearly constant temperature of 22.0° to 22.5°C was maintained in spite of normal tidal fluctuations; and 3) this constant temperature period is bracketed by two 24 h transitional periods that are initiated almost coincidently with wind directional changes. It appears that the sequence and relationship of these wind and water temperature data may be explained by and provide additional evidence and documentation of wind-induced upwelling along the northeastern North Carolina coast previously reported by Wells and Gray (1960), Carter, Pritchard and Carpenter (1966) and Boicourt (1973). Indeed, an important conclusion that can be drawn from this sequence and relationship of data is that temperature, salinity and current velocity records in and near a barrier island inlet can furnish much information about the exchange and mixing processes on the adjacent continental shelf, especially when there are large differences in temperature and salinity between the sound and shelf waters.

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