. Coastal currents along the Atlantic coast of the United States. Ocean currents; Tides. 6 U. S. COAST AND GEODETIC SURVEY the tide and current curves in The Narrows, New York Harbor, for August 8-9, 1922, the current curve being the dashed-Hne curve, rep- resenting the velocities of the current in the center of the channel, and the tide curve being the full-line curve, representing the rise and fall of the tide at Fort Hamilton, on the eastern shore of The Narrows. The diagrams of figure 4 were drawn by plotting the heights of the tide and the velocities of the current to the same time scale
. Coastal currents along the Atlantic coast of the United States. Ocean currents; Tides. 6 U. S. COAST AND GEODETIC SURVEY the tide and current curves in The Narrows, New York Harbor, for August 8-9, 1922, the current curve being the dashed-Hne curve, rep- resenting the velocities of the current in the center of the channel, and the tide curve being the full-line curve, representing the rise and fall of the tide at Fort Hamilton, on the eastern shore of The Narrows. The diagrams of figure 4 were drawn by plotting the heights of the tide and the velocities of the current to the same time scale and to such velocity and height scales as will make the maximum ordi- nates of the two curves approximately equal. The time axis or axis of X represents the line of zero velocity for the currents and of mean sea level for the tide, the velocity of the current being plotted in accordance with the scale of knots on the right, while the height of the tide reckoned from mean sea level was plotted in accordance with the scale in feet on the left. From figure 4 it is seen that the corresponding features of the Knots. Figure 4.—Tide and current curves, The Narrows, New York Harbor, August 8-9, 1922. tide and current at this station bear a nearly constant time relation to each other. This approximate constancy in time relations between current and tide is characteristic of tidal waters in which the diurnal inequality is small, and permits the times of slack and of strength of the current to be referred to the times of high and low water. Thus, from figure 4 we find that the strengths of the current come about an hour before the times of high and low water, while the slacks come about 1 % hours after high water and 3 hours after low water. In this connection, however, it is to be noted that the time relations between corresponding phases of tide and current at any place frequently vary in consequence of disturbing effects of wind, weather, and fresh- water run-off. Quite apart from th
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