Bài giảng Địa lý kinh tế - Chương 4: Thủy triều

Nội dung text: Bài giảng Địa lý kinh tế - Chương 4: Thủy triều

1. Chapter 4 Tide and tidal currents Nội dung 1. Thuật ngữ thiên văn và thuỷ văn 2. Lực tạo triều 3. Phân tích thuỷ triều 4. Dự báo triều 5. Thuỷ triều Biển đông 6. Cửa sông và thuỷ triều vùng cửa sông 7. Bài tập
2. Thuật ngữ thiên văn  Thiên cầu hay mặt cầu bầu trời  Trục vũ trụ  Thiên cực bắc và thiên cực nam  Thiên đỉnh và thiên đế  Mặt phẳng chân trời  Đ•ờng chân trời, xớch đạo trời.  Thiên cầu bắc và thiên cầu nam.  Kinh tuyến trời.  Điểm bắc và điểm nam, điểm đông và điểm tây.  Vòng giờ, vòng nhật động. Vòng hoàng đạo, bạch đạo.  Xuân phân (21/III),thu phân (23/IX),hạ chí (22/VI), đông chí (22/XII).  Ngày sóc th•ợng huyền , ngày vọng hạ huyền . Thuật ngữ thuỷ văn - Đỉnh triều - Chân triều - Tr, Td - Kỳ n•ớc c•ờng, kỳ n•ớc kém - Chu kỳ triều - “0 lục địa” , “0 độ sâu” - Độ lớn thuỷ triều - Biên độ triều
3. Tidal Characteristics single waves - stretch across entire ocean basins. shallow-water waves – wavelengths greatly exceed the depth of the ocean. complex interactions of moon and sun
4. Why Care About Tides?
5. Aquaculture
6. The Tides of the Bay of Fundy
7. Origin of the Tides Unlike wind-driven surface waves and unlike tsunamis, tides are caused by two principal factors: –Gravitational attraction –Centrifugal force
8. Gravitational Attraction All masses are drawn to each other. The moon because of its closeness to the Earth exerts a greater gravitational effect on the Earth than the Sun, despite the fact that the Sun is much more massive than the Moon. x = ?
9. Gravitational Effect of Moon Centrifugal Forces: Center of Rotation
10. 2 Bulges from Gravitational Attraction & Centrifugal Force
11. Gravitational forces Tractive force 3gM F F sin( ) F sin( ) F sin2 s m a s 2K3
12. Distribution of tractive forces over the Earth surface. Ratio of the tractive forces od the Moon and the Sun. Symbol Moon Sun Dimension M 0.0123 333,000 (-) K 60.3 23,500 (-) 3gM/(2K3) 0.82*10-6 0.38*10-6 (m/s2)
13. The equilibrium theory assumed that the Earth is fully covered with water The plane of the moon is in the plane of the equator
14.  why not exactly 24 hours or 12 hours?  Moon moves forward in it’s orbit each day. – Takes 50 additional minutes for a spot on the Earth’s surface to regain it’s position relative to the Moon. o o E = 15.041 /h m = 0.549 /h 2 360o 2T o 24.84h E m 14.49 /h T = 12.42 h = 12 h 25’
15. The plane of the moon makes an angle with the plane of the equator
16. Joint effect of moon and sun on the tides  Spring tides occur when the Earth, Sun, and Moon are aligned. – New Moon and Full Moon phases – Constructive interference  Neap tides occur when the Sun and Moon are aligned at right angles to one another. – Quarter Moon phases – Destructive interference
17.  Spring tide: phase when tidal range is maximal.  Neap tide: phase when tidal range is minimal.  There are 2 spring and 2 neap tides each month 2 360o 2T o 708h m s 0.508 /h T = 354 h = 14.8 days
18. Moving position of the perigeum Elliptical orbit of the Earth
19. Relative motions of moon and sun in relation to the celestrial sphere 3gM 3gM n Fs 3 sin2 3 Ao  Ai cos(it i ) 2K 2K i 1 Ao = constant Ai = amplitude of component i i = angular speed of component i = jE + k m +l s + m p in which E m s p are the angular speeds of the Earth, the Moon, the Sun, perigeum of the moon i = phase of component i at t = 0.
20. Periods and angular speeds Origin Angular speed in o/hour Period Rotation Earth Rotation Earth 15.041069 0.997 days Moon around Earth 0.549016 27.32 days Earth around Sun 0.041069 365.24 days Perigeum Moon 0.004642 8.85 years Nodes lunar orbit 0.002206 18.60 years The variation due to the revolution of the nodes is taken into account by multiplying the amplitude with a factor fi and adding a phase shift ui to the harmonic terms The number of harmonic terms is large: - The orbits are not in the plane of the equator, which cause declination tides (mainly diurnal); - The distance between the Earth and the moon and sun are not constant, as their orbits are ellipses. The distances vary and also the angular speed. That causes the elliptical tides (both diurnal and semi-diurnal).
21. Main astronomic constituents of the tide Gro Sym Frequency Period Angular Astronomi Type of constituent up bol (hours) speed c (o/hour) coefficients I M2 2we-2wm 12.42 28.9841 0.908 semi-diurnal principle lunar tide S2 2we-2ws 12.00 30.0000 0.423 semi-diurnal principle solar tide K1 we 23.94 15.0411 0.531 diurnal lunar-solar declination tide O1 we-2wm 25.80 13.9430 0.377 diurnal lunar declination tide II P1 we-2ws 24.07 14.9589 0.176 diurnal solar declination tide N2 2we-wm+wp 12.66 28.4397 0.174 semi-diurnal lunar elliptic tide K2 2we 11.97 30.0821 0.115 semi-diurnal lunar-solar declination tide constituents of the tide (conts) III Q1 e-3m+p 26.87 13.3987 0.072 diurnal lunar elliptic tide L2 2e-m-p 12.19 29.5285 0.026 semi diurnal lunar elliptic tide IV Mf 2m 328 1.0980 0.156 long periodic lunar tide Mm m-p 661 0.5444 0.083 long periodic lunar tide Ssa 2s 4383 0.0821 0.026 long periodic solar tide V Sa s 8759 0.0411 0.012 long periodic solar tide Msm m-2s+p 764 0.4715 0.012 Msf 2m-2s 354 1.0159 0.008 Mtm 3m-p 219 1.6424 0.030 M1 e-m+p 24.83 14.4967 0.030 1 e-3s 24.13 14.9179 0.010 1 e+2s 23.80 15.1232 0.008 J1 e+m-p 23.10 15.5854 0.030 001 e+2m 22.31 16.1391 0.016 2N2 2e-4m+2p 12.91 27.8954 0.024 m2 2e-4m+2s 12.87 27.9682 0.022 n2 2e-3m+2s- 12.63 28.5126 0.034 l2 p 12.22 29.4556 0.007 T2 2e-m- 12.02 29.9590 0.025 2s+p 2e-3s
22. Shallow water tidal - Bottom friction; - Variable propagation speed of the tidal wave. - Variable propagation speed of the tidal wave.
23. Shallow water tides Symbol Origin Frequency Period Angular Remarks speed (hrs) (deg./h) MNS2 M2+N2-S2 2e-5m+2s+p 13.13 27.4238 semi-diurnal 2MS2 2M2-S2 2e-4m+2s 12.87 27.9682 2SM2 2S2-M2 2e+2m-4s 11.61 31.0159 MK3 M2+K1 3e-2m 8.18 44.0252 terdiurnal 2MK3 2M2-K1 3e-4m 8.39 42.9271 SK3 S2+K1 3e-2s 7.99 45.0411 SO3 S2+O1 3e-2m-2s 8.19 43.9430 M4 2M2 4e-4m 6.21 57.9682 quarter diurnal MS4 M2+S2 4e-2m-2s 6.10 58.9841 MN4 M2+N2 4e-5m+p 6.27 57.4238 MK4 M2+K2 4e-2m 6.09 59.0662 S4 2S2 4e-4s 6.00 60.0000
24. Shallow water tides Symbol Origin Frequency Period Angular Remarks (hrs) speed (deg./h) M6 3M2 6e-6m 4.14 86.9523 sixth diurnal 2MS6 2M2+S2 6e-4m-2s 4.09 87.9682 2MN6 2M2+N2 6e-7m+p 4.17 86.4079 2SM6 2S2+M2 6e-2m-4s 4.05 88.9841 MSN6 M2+S2+N2 6e-5m-2s+p 4.12 87.4238 S6 3S2 6e-6s 4.00 90.0000 M8 4M2 8e-8m 3.11 115.9364 eighth diurnal 3MS8 3M2+S2 8e-6m-2s 3.08 116.9523 2(MS)8 2M2+2S2 8e-4m-4s 3.05 117.9682 2MSN8 2M2+S2+N2 8e-7m-2s+p 3.07 117.4079 S8 4S2 8e-8s 3.00 120.0000 Phõn loại thủy triều Bán nhật Triều hỗn hợp Kiểu triều triều BN triều Nhật triều Nhật triều đều không đều không đều hK1 hO1 H 0.0 4.0 hM 2 H K1 + H 01 F = 3 H M2 + H S2