Nước đại dương luôn luôn chuyển động do tác động của thuỷ triều, gây ra bởi lực hấp dẫn của Mặt Trăng và Mặt Trời đối với Trái Đất, sóng và hải lưu do tác dụng của gió. Các dòng bù trừ phát sinh do sự thiếu hụt của nước. | 122 6 Rotational Effects diffusion are disabled. The TDV Superbee advection scheme is used for both the nonlinear terms and in the vertically integrated continuity equation. Results Figure shows the propagation of a coastal Kelvin wave attaining maximal amplitude at the coast and showing an exponential decrease in amplitude away from the coast. Numerical diffusion is apparent resulting in a decrease of wave amplitude along the coast. Storm surges can stimulate such coastal Kelvin waves in shelf seas of horizontal dimensions exceeding the Rossby radius of deformation. The North Sea is one example of this. Fig. Exercise 15. Snapshot of the deformation of the sea surface caused by a coastal Kelvin wave in the northern hemisphere Sample Codes and Animation Script The folder Exercise 15 on the CD-ROM contains the computer codes for this exercise. Additional Exercise for the Reader Repeat this exercise with different values of the Coriolis parameter and total water depth and explore the resultant wave patterns. The reader might also introduce some bottom friction. Geostrophic Flow Scaling If we use the Coriolis force for reference we can defin various force ratios that essentially compare different time scales. The temporal Rossby number see Geostrophic Flow 123 Sect. compares the inertial period with the time scale of a process. The Coriolis force influence or even controls processes that have time scales of or exceeding the inertial period. On the other hand the ratio between the nonlinear terms and the Coriolis force is called the Rossby number and is define by U fL where U is a typical speed f is the inertial period and L is the lengthscale of a process. Again this is a comparison of time scales whereby L U is the time it takes for a f ow of speed U to travel a distance of L. For small Rossby numbers Ro 1 nonlinear terms are negligibly small compared with the Coriolis force and therefore can be ignored. The .
