北部灣冬夏季環(huán)流及其水交換的數(shù)值模擬研究
本文關(guān)鍵詞: 北部灣 環(huán)流 水交換 出處:《中國海洋大學(xué)》2014年碩士論文 論文類型:學(xué)位論文
【摘要】:北部灣位于我國南海的西北部,介于16°~22°N,105°30′~110°E之間,為天然半封閉淺水海灣,它東接雷州半島和海南島,北依廣西,西臨越南,南與南海相通,平均水深為38m,最大水深為106m,水域面積約12.8×104km2。因其沿岸眾多的河流,獨(dú)特的地理位置,北部灣形成了由河口生態(tài)系統(tǒng)、海灣生態(tài)系統(tǒng)組成的獨(dú)特自然環(huán)境。研究北部灣的環(huán)流規(guī)律以及北部灣海域的水交換程度從理論意義上說可以更好地了解北部灣的動力機(jī)制及物理自凈能力,從實用意義上說能夠協(xié)助更好地開發(fā)利用北部灣的自然環(huán)境、生態(tài)環(huán)境,為北部灣海域環(huán)境的保護(hù)提供科學(xué)依據(jù)和技術(shù)支持。本文以北部灣為研究對象,運(yùn)用FVCOM三維水動力模型數(shù)值模擬了北部灣冬夏季的風(fēng)生潮致環(huán)流,同時利用Tracer-Tracking模塊,對北部灣的水交換規(guī)律進(jìn)行了研究。主要工作內(nèi)容和結(jié)果如下: 1.應(yīng)用FVCOM模式,建立了北部灣三維水動力模型,通過灣內(nèi)一個驗證點連續(xù)九天的潮流潮位實測驗證資料,以及繪制同潮時線和等振幅線圖同前人的研究結(jié)果進(jìn)行比對,驗證了該模式模擬結(jié)果的正確性。同時得到以下結(jié)論: (1)潮波由灣口向灣內(nèi)傳播,振幅在北部灣頂部達(dá)到最大。其中全日分潮K1,O1在北部灣起主要作用。K1分潮振幅的最大值超過90cm,O1分潮振幅的最大值在100cm以上。O1和K1分潮的遲角均在越南順化附近形成一個無潮點,同潮時線沿?zé)o潮點逆時針旋轉(zhuǎn)。北部灣的M2,S2分潮的振幅明顯小于全日分潮。M2和S2分潮的遲角由灣口向灣頂傳播,不斷增大。 (2)北部灣的潮流形式主要為往復(fù)流,方向基本與岸線一致。雷州半島西側(cè)附近海域,海水流向與岸線較一致;北部灣北緯20°以南海域,從北向南,潮流的流向從東北-西南向逐漸轉(zhuǎn)成西北-東南向。流速上看,瓊州海峽西出口處流速最大,其次為海南島西南側(cè)近岸海域。 (3)潮致余流在海南島西北向和海南島鶯歌咀附近各形成一個閉合的逆時針環(huán)流。潮致余流從瓊州海峽流入北部灣,沿廣西沿岸,而后向南流動,一部分與沿海南島向北流動的流形成一個逆時針環(huán)流,另一部分向西而后向南流動,在鶯歌咀附近形成了一個小的逆時針閉合環(huán)流。 2.根據(jù)The National Centers for Environmental Prediction (NCEP)提供的冬夏季月平均風(fēng)場數(shù)據(jù),本文在FVCOM水動力模型的基礎(chǔ)上,加入了冬夏季風(fēng)場作為驅(qū)動條件,對北部灣冬夏季的風(fēng)生潮致環(huán)流進(jìn)行數(shù)值模擬。計算結(jié)果如下: (1)冬季北部灣的越南沿岸存在一個狹長的逆時針閉合環(huán)流。表層環(huán)流從瓊州海峽自東向西流入北部灣,分別向北、西、西北沿廣西、越南沿岸流動,還有一部分外海水從海南島南部流入灣內(nèi),向西北方向流動,與越南沿岸的東南向流相互作用,形成一個狹長的閉合逆時針環(huán)流。中層與表層環(huán)流結(jié)構(gòu)有明顯區(qū)別,底層與中層環(huán)流結(jié)構(gòu)基本一致。 (2)夏季表層環(huán)流依然是自東向西經(jīng)瓊州海峽流入北部灣,在北部灣內(nèi)形成了兩個逆時針環(huán)流。海南島西側(cè)沿岸流向北流動,在北緯19°,,東經(jīng)108°左右形成一個不閉合的逆時針環(huán)流。北緯19°附近有一支明顯向東流動的環(huán)流,沿海南島南岸流出北部灣,并且在北部灣南出口附近形成了一個順時針旋轉(zhuǎn)的環(huán)流。中層閉合環(huán)流的位置發(fā)生了偏移,底層與中層環(huán)流結(jié)構(gòu)一致。 3.本文以雷州半島西南側(cè)新地村——海南省澄邁縣馬村港,海南省南側(cè)三亞——越南峴港為界,通過示蹤物方法,數(shù)值模擬了北部灣水交換情況,計算出北部灣的半交換時間和平均存留時間。結(jié)論如下: 冬季北部灣平均存留時間為430天,夏季北部灣平均存留時間為588天。冬夏季北部灣水交換的相同點在于,水交換能力自水交換邊界向灣內(nèi)逐漸減弱,距水交換邊界越近,水交換能力越強(qiáng),反之,水交換能力越弱。不同點在于,灣內(nèi)水交換平均存留時間的分布有著顯著的不同。
[Abstract]:The Beibu Gulf is located in the north - west of the South China Sea , between 16 擄 ~ 22 擄 N , 105 擄 30 ' ~ 110 擄 E . It is a natural semi - enclosed shallow water bay . It is a unique natural environment consisting of estuary ecosystem and Gulf ecosystem . 1 . The model of the three - dimensional hydrodynamic model in Beibu Gulf is established by applying the model of the model , and the correctness of the simulation results is verified by comparing the measured data of tidal current at one point in the bay for nine consecutive days . ( 1 ) The tidal wave propagates from the bay mouth to the bay , and the amplitude reaches the maximum at the top of the Beibu Gulf . ( 2 ) The tidal current form of Beibu Gulf is mainly the reciprocating flow , the direction is basically the same as that of the coastline . The flow direction of the sea area near the west side of the Leizhou Peninsula is consistent with the coastline ; the flow direction from the north to the south and the tidal current flows from the northeast to the southeast to the southeast to the southeast . ( 3 ) The tidal residual flow forms a closed anti - clockwise circulation in the northwest of Hainan Island and Yinggezui , Hainan Island . 2 . Based on the water power model of winter and summer provided by The National Centers for Environmental Prediction ( NCEP ) , this paper adds the winter summer monsoon field as the driving condition on the basis of the water power model of the model . The numerical simulation is carried out on the circulation of wind - induced tide in the winter and summer of Beibu Gulf . The results are as follows : ( 1 ) There is a narrow and counterclockwise closed circulation along the Vietnamese coast in Beibu Gulf in winter . The surface circulation flows from east to west to Beibu Gulf from east to west , and flows along the coast of Guangxi and Vietnam respectively . Some of the outer seawater flows from the south of Hainan Island to the Gulf . It also flows in the northwest direction . It forms a long and closed anti - clockwise circulation . The middle layer and the surface circulation structure are obviously different , and the bottom layer is basically consistent with the middle layer circulation structure . ( 2 ) The surface circulation in summer is still flowing from east to west to Beibu Gulf through the Qionghai Strait . Two anticlockwise circulation is formed in Beibu Gulf . There is an unclosed anti - clockwise circulation around the west coast of Hainan Island . There is a circulation around the south bank of Hainan Island , which flows out of the Beibu Gulf , along the south bank of Hainan Island , and a clockwise rotating circulation is formed near the south exit of the Beibu Gulf . The position of the middle closed loop is offset , and the bottom layer is consistent with the middle layer circulation structure . 3 . According to the method of tracer , the water exchange in Beibu Gulf is simulated by means of tracer method , and the half - exchange time and average residence time of Beibu Gulf are calculated . The conclusion is as follows : The average residence time of Beibu Gulf in winter is 430 days . The average residence time of Beibu Gulf in summer is 588 days . In winter and summer , the water exchange capacity gradually decreases from the water exchange boundary to the bay , the closer the water exchange boundary is , the stronger the water exchange capacity , and the weaker the water exchange capacity . The difference lies in that the distribution of the average residence time of the water exchange in the bay is significantly different .
【學(xué)位授予單位】:中國海洋大學(xué)
【學(xué)位級別】:碩士
【學(xué)位授予年份】:2014
【分類號】:P731.27
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