. Collected reprints / Atlantic Oceanographic and Meteorological Laboratories [and] Pacific Oceanographic Laboratories. Oceanography FIGURE 4. Amphidromic systems of the Mj tidal constituent (semidaily lunar tide) in the North Sea. The cotidal lines show the progress of the tide each constituent hour (30 ' phase change), the dotted corange lines show the decrease in feet of the Mj tidal range away from the shore. From Doodson and Warburg ( 1941)- Equation 1 states that the time rate of change of the downchannel horizontal velocity u is equal to the acceleration of gravity g multi
. Collected reprints / Atlantic Oceanographic and Meteorological Laboratories [and] Pacific Oceanographic Laboratories. Oceanography FIGURE 4. Amphidromic systems of the Mj tidal constituent (semidaily lunar tide) in the North Sea. The cotidal lines show the progress of the tide each constituent hour (30 ' phase change), the dotted corange lines show the decrease in feet of the Mj tidal range away from the shore. From Doodson and Warburg ( 1941)- Equation 1 states that the time rate of change of the downchannel horizontal velocity u is equal to the acceleration of gravity g multiplied by the downchannel slope of the sea surface, whose displacement above mean water is r\\ t is the time elapsed after high water at the source; and x is the distance away from the source of the tide as measured along the axis of the channel. Equation 2 states that the time rate of change of the sea surface displacement rj is equal to the mean depth h multiplied by the horizontal rate of change of the downchannel velocity u. Assuming that the mean depth h is uniform through- out the channel, a tide with a period T and an amplitude a (one-half the range) would be described by t? = a cos H-t)] â GT-GK'-f)] (3) (4) where c = (gh)112 is the speed of propagation at which the shape of the sea surface moves down the channel. For oceanic and shelf depths c is 200 and 31 m/sec, respectively. If the depth h were representative of the open ocean (h = 4000 m) and the amplitude of the tide were a = m, the maximum tidal current according to (4) would be cm/sec, a relatively small speed. On the other hand, if the depth were representative of the continental shelves (h = 100 m), the corresponding current would be cm/sec. For a given tidal ampli- tude, the maximum tidal currents are inversely pro- portional to the square root of depth. In very shallow water, where (4) would predict unrealistically large currents, the formula is not applicable since turbulent dissipation and bot
Size: 3730px × 670px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., book, bookcentury1900, bookcollectionamericana, bookleafnumber225
