Shelfwater response to the cold winters of 1977 and 1978 in the South Atlantic Bight (SAB)
Mathews, Thomas D
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Hydrographic data from winter and summer cruises during the 1976 and 1979 period were used to illustrate atypical oceanographic conditions in the SAB, especially during the cold winters of 1977 and 1978. During this period meteorological conditions resulted in unusually low water temperatures in nearshore regimes [<6 degrees C in South Carolina coastal waters in January 1977]. During other winter cruises surface waters were cooler off Georgia than off South Carolina. Zones of upwelling were observed regularly near Cape Canaveral and off Charleston, while Gulf Stream instrusions were detected at many outer shelf locations. Salinities indicative of runoff occurred near the coast, from South Carolina to Florida during the winter cruises. High salinities [>36 o/oo] were also measured during the winter cruises in some coastal areas, indicating Gulf Stream intrusions. Suface salinities >35 o/oo near river mouths were observed during the summers of 1977 and 1978, correlating well with drought conditions in the coastal states. Surface circulation, as derived from density distributions, was atypical throughout much of the period of this study. The cyclonic eddy normally in Long Bay [south of Cape Fear] was not well-defined or present during the summer cruises, but was qutie distinct during winter 1977 in conjunctin with three other cyclonic eddies at midshelf locations. In addition, a rather continuous coastal countercurrnt was present during winter 1977 from Long Bay to Cape Canaveral. The summer 1976 circulation, however, did not have a long Bay eddy as usual or it was displaced offshore.