Do độ che phủ bề mặt Trái Đất tới 71% nên các đại dương có ảnh hưởng lớn tới sinh quyển. Sự bốc hơi nước của các đại dương quyết định phần lớn lượng giáng thủy mà Trái Đất nhận được, nhiệt độ nước của các đại dương cũng quyết định phần lớn khí hậu và kiểu gió trên Trái Đất. | 160 6 Rotational Effects Fig. Exercise 21. Shape of the density interface after 10 days of simulation Fig. Exercise 21. Currents arrows averaged over 2x2 grid cells and Eulerian tracer concentration contours in the top layer after 10 and days of simulation. Cross-frontal fl w attains speeds of 50 cm s of this instability the front starts to meander forming alternating zones of positive and negative relative vorticity Fig. . Baroclinic eddies appear soon after this mixing whereby cyclonic eddies remain centered along the axis of the front while anticyclonic eddies are moved away from the frontal axis. The diameter of eddies Exercise 21 Frontal Instability 161 Fig. Exercise 21. Currents arrows averaged over 2x2 grid cells and pressure anomalies solid contours emphasise low pressure centres in the bottom layer after 10 and 17 days of simulation. Deep cyclones attain maximum f ow speeds of 20 cm s is 10-20 km. Later in the simulation not shown eddies interact with each other and produce vigorous lateral mixing in the entire model domain. Surface eddies are associated with swift currents of speeds exceeding 50 cm s. Bottom currents of noticeable speed benthic storms start to develop from day 10 of the simulation onward and approach values of 20cm s by the end of the simulation Fig. . Interestingly the structure of disturbances in the bottom layer is different from those in the upper layer. Here it is exclusively the cyclonic eddies that trigger the growth of instabilities. This process leading to the preferred creation of cyclonic eddies is called cyclogenesis. Sample Code and Animation Script The folder Exercise 21 of the CD-ROM contains the computer codes for this exercise. The fil gives more information. 162 6 Rotational Effects Additional Exercise for the Reader Repeat this exercise for an ocean uniform in density p1 p2 1028 kg m-3 to explore whether the barotropic instability process alone can produce a .
