. Collected reprints / Atlantic Oceanographic and Meteorological Laboratories [and] Pacific Oceanographic Laboratories. Oceanography THE SHOREFACE PROFILE 263 rents occur. They, too, are significant transporters of sand. Without these storm-driven flows, the coasts of our planet would have a markedly different appearance. Storms, whether of tropical or extratropicalorigin, are rapidly moving counterclockwise wind systems that may be a thousand or more kilometers in lateral extent. Winds intensify rapidly toward the storm center, and in hurri- canes, by definition, exceed 74 mph.
. Collected reprints / Atlantic Oceanographic and Meteorological Laboratories [and] Pacific Oceanographic Laboratories. Oceanography THE SHOREFACE PROFILE 263 rents occur. They, too, are significant transporters of sand. Without these storm-driven flows, the coasts of our planet would have a markedly different appearance. Storms, whether of tropical or extratropicalorigin, are rapidly moving counterclockwise wind systems that may be a thousand or more kilometers in lateral extent. Winds intensify rapidly toward the storm center, and in hurri- canes, by definition, exceed 74 mph. The extent to which the shelf water column will couple with storm winds depends on the trajectory of the storm with respect to the geometry of the shelf. Sustained regional coupling of water flow with wind flow appears to occur when the winds blow equatorward along the length of eastward- facing coasts (Beardsley and Butman, 1974) or blow poleward along the length of westward-facing coasts (Smith and Hopkins, 1972). Under such conditions, water in the surface layer will be transported landward as a consequence of the Coriolis effect. Coastal sea level will rise until the coastal pressure head balances bottom friction, and bottom water can flow seaward as rapidly as surface water flows landward. Beardsley and Butman report up to 100 cm of coastal setup under such condi- tions. Since the sea surface is inclined against the coast, there is a gradient of seaward-decreasing pressure at any reference depth. A parcel of water, accelerated by the pressure force, has its trajectory steadily deflected to the right by the Coriolis "force," until finally, it is flowing along the isobars and the pressure and Coriolis terms balance (Fig. 5). inner shelf velocity field. The complex velocity structure of the coastal zone is best approached in terms of the interaction of three major flow strata (Ekman, 1905; see Neumann and Pierson, 1966, p. 202). These are an upper boundary layer, a
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