海洋科學特論跨校聯合授課 波浪潮汐與近岸作用 授課教師 : 中山大學海科院王玉懷副教授 2012.10.1 文獻引用 : Tally, Lyne etc. 2011. http://www-pord.ucsd.edu/~ltalley/sio210 Stewart, Robert, 2008. http://oceanworld.tamu.edu/ocean410/ Tomzack, Matthias, 2002. http://www.es.flinders.edu.au/~mattom/introoc/index.html 網路攫取相關資料
海嘯半日潮全日潮慣性波湧浪風浪波浪的分類 : 依週期 Waves in the Ocean (LeBlond & Mysak, 1978) 球面波能譜毛細波週期
波浪分類 : 週期驅動力 回復力
線性波理論 R. Stewart, 2008 1. Linear Theory of Ocean Surface Waves Assumptions: 1. the amplitude of waves on the water surface is infinitely small (so the surface is almost exactly a plane). 2. the flow is 2-dimensional with waves traveling in the x-direction. 3. the Coriolis force and viscosity can be neglected. z = a sin( k x - ω t)
離散關係 : Dispersion Relation Wave frequency ω is related to wave number κ by the dispersion relation 相位速度 :Phase Velocity The phase velocity c is the speed at which a particular phase of the wave propagates, for example, the speed of propagation of the wave crest. In one wave period T the crest advances one wave-length L and the phase speed is c = L / T = ω / κ. 波群速度 : Group Velocity The concept of group velocity c g is fundamental for understanding the propagation of linear and nonlinear waves. First, it is the velocity at which a group of waves travels across the ocean. More importantly, it is also the propagation velocity of wave energy R. Stewart, 2008
Dispersion Relation Phase Velocity Group Velocity ω 2 = g κ tanh ( κd ) Deep-water wave ω 2 = g κ d > L / 4 Shallow-water wave ω 2 = g κ 2 dd< L / 11 R. Stewart, 2008
有意義波高 ( 示性波高 ) Significant Wave-Height What do we mean by wave-height? If we look at a wind-driven sea, we see waves of various heights. Some are much larger than most, others are much smaller. A practical definition that is often used is the height of the highest 1/3 of the waves, H1/3 The height is computed as follows: measure wave-height for a few minutes, pick out say 120 wave crests and record their heights. Pick the 40 largest waves and calculate the average height of the 40 values. This is H1/3 for the wave record. The concept of significant wave-height was developed during the World War II as part of a project to forecast ocean wave-heights and periods. Wiegel (1964) reports that work at the Scripps Institution of Oceanography.... wave-height estimated by observers corresponds to the average of the highest 20 to 40 per cent of waves... Originally, the term significant wave-height was attached to the average of these observations, the highest 30 percent of the waves, but has evolved to become the average of the highest one-third of the waves, (designated Hs or H1/3) R. Stewart, 2008
波高 ~ 波能 / 波譜 More recently, significant wave-height is calculated from measured wave displacement. If the sea contains a narrow range of wave frequencies, H1/3 is related to the standard deviation of sea-surface displacement (NAS, 1963: 22; Hoffman and Karst, 1975) H H1/3 = 4 < z 2 > 1/2 where < z 2 > 1/2 is the standard deviation of surface displacement R. Stewart, 2008
Wind Wave Development 風浪與湧浪 2002 Brooks/Cole, a division of Thomson Learning, Inc.
Wind Waves Approaching Shore 波浪遇淺 What happens when wind waves break against the shore? 2002 Brooks/Cole, a division of Thomson Learning, Inc.
碎波 溢出型 (Spilling) 崩捲型 (Plunging) 崩塌型 (Surging)
波浪折射 離岸流 : Special weather conditions can cause rip currents to form. http://www.srh.noaa.gov/mlb/?n=ripcurrent_rules
引潮力 http://geology.uprm.edu/morelock/tide.htm
The Equilibrium Theory of Tides The action of gravity and inertia on particles at five different locations on Earth. Forces are balanced only at point CE, the center of Earth. Note the bulges that are aligned with the moon as Earth spins on its axis. The key to understanding di the equilibrium i theory of tides is to see Earth turning beneath these bulges. 2002 Brooks/Cole, a division of Thomson Learning, Inc.
平衡潮理論 The gravitational force of the moon (which varies on Earth depending on distance from the moon) on a particle of mass m at a point, a, is: G is the gravitational constant = 6.67 10-11 N kg-1 m2 M is the mass of the moon; m is the mass of the earth P is the earth moon distance; R is the radius of the earth
At point a, the imbalance of forces is: At point b:
大潮 vs 小潮
http://hsmaterial.moe.edu.tw/file/bes/3-2-2-31/3-2-2-3-g/photo_3-2-2-3-g1.html 全日潮 vs 半日潮
潮位變化 : 潮差 相位
12 Matsu Tidal Elevations(m) at Western Taiwan Strait 8 4 10 117 118 119 120 121 122 DY 5 26 26 MS 0 8 Wuchiu 25 WC 25 24 KM 24 4 23 23 0 Kinmen 22 22 117 118 119 120 121 122 2/1/99 2/2/99 2/3/99
The Kelvin Wave Mode +u +y 0 e y u g f y
海嘯的形成 崩山火山爆發隕石 斷層滑動 地震 深水波 淺化崩捲 Thurman, H. V. (1993) Essentials of Oceanography, 4th ed.
海嘯歷史事件 1917 年 06 月 26 日薩摩亞群島, 浪高 26 米 1933 年 03 月 02 日日本三陸海域, 浪高 29 米 1946 年 04 月 01 日阿留申群島, 浪高 35 米 1960 年 05 月 22 日智利, 浪高 25 米 1964 年 03 月 28 日阿拉斯加灣, 浪高 70 米 1979 年 10 月 16 日法國尼斯, 浪高 3 米 1992 年 09 月 01 日尼加拉瓜, 浪高 11 米 1993 年 07 月 01 日日本, 浪高 5 米 1994 年 06 月 03 日印尼東爪哇, 浪高 60 米 1998 年 07 月 17 日巴布亞新幾內亞, 浪高 49 米
Tsunami Excitation Entire Fault http://www.google.com.tw/imgres?um=1&hl=zh-tw&lr=lang_zh-tw&tbs=lr:lang_1zh- TW&tbm=isch&tbnid=bMqAztRYr_iWpM:&imgrefurl=http://www.earth.sinica.edu.tw/~smdmc/2004122 6_Sumatra/20050516.pps&docid=Fm_RDffwTLZ9JM&imgurl=http://www.earth.sinica.edu.tw/~smdmc/2 0041226_Sumatra/20041226_Sumatra/2004_Simulation/2004_animation.gif&w=510&h=632&ei=CvdfUL yyoexsmaxr3ogwbq&zoom=1&iact=rc&dur=526&sig=101959201106342285102&page=1&tbnh=14 3&tbnw=115&start=0&ndsp=21&ved=1t:429,r:6,s:0,i:87&tx=76&ty=79&biw=1133&bih=882 Page created by W. G. Huang
衛星圖片顯示亞齊省 ( 印度尼西亞 ) 首府班達亞齊海濱地區受海嘯襲擊前後的情形 上圖拍攝於 6 月 23 日, 下圖拍攝於 12 月 28 日
內波
傅科憲, 2011
Fu( 傅科憲 )et al., 2011
Wang et al., 2007 Geophysical Research Letter 內波將富含營養鹽深層海水送往東沙環礁海域 細菌的分解造成水中溶氧量的減少 營養塩釋出, 浮游植物利用光合作用大量繁殖
SAR 2005.4.28 m T-string 2008.5.7 6am-11:30am IWs on SAR Cold water entrainment t Corals Chla MODIS 2005.5.14 Nutrients cold~ NO 3 -