基于FVCOM模型的珠江河口及其邻近海域的潮汐模拟

基于FVCOM模型,将珠江河网、河口和口外海区作为整体,建立完全三维数值模式,对珠江河口及其邻近海域的潮汐进行数值模拟.采用23个潮位站的潮汐表水位资料对模式进行验证,结果表明模式能比较准确地重现珠江河口的潮汐变化过程.通过对计算结果进行潮汐调和分析,给出了珠江河口区域及近岸海域8个主要分潮的同潮图,讨论了潮波的传播特征.珠江河口潮汐属于混合潮类型,潮型系数介于0.8—1.5.浅水分潮成分很小,最大振幅不超过5cm.对珠江河口的潮差进行统计,给出了珠江河口大潮和小潮期间的潮差大小及分布,大潮时潮差介于2.2—3.1m,小潮时减小到0.6—1.1m.     

北部湾潮波数值研究

利用普林斯顿海洋模式(POM08)建立了北部湾及其临近海区潮汐潮流数值模式,模拟了K1,O1,M2和S2这4个主要分潮,分析了模拟的潮汐和潮流分布特征,从潮波能量的角度讨论了琼州海峡对北部湾潮波系统的影响,并给出北部湾潮能的耗散情况。研究表明,北部湾是典型的全日潮海区,K1和O1分潮在南部湾口形成半个旋转潮波系统,无潮点位于越南顺安附近岸边。琼州海峡中的欧拉潮汐余流为西向流,潮余流造成的水通量约为0.034×106m3/s;余流出海峡西口后,先折向北,然后转向南流出湾外。研究海区中两个强潮流区分别位于琼州海峡和海南岛的西侧,同时这也是两个潮能的高耗散区。北部湾的潮能自南部湾口由外海传入,通过西口涌入琼州海峡,到达海峡东口时日潮波的能量已基本耗散殆尽,在海峡内耗散的4个分潮的潮能约为3.33 GW,相当于北部湾潮能耗散量的35%左右。数值试验表明,琼州海峡作为潮能耗散的重要海区,其存在对于北部湾潮波系统的形成具有较大影响。计算了底边界潮能耗散,结果表明在北部湾和琼州海峡,底边界耗散的潮能分别占该海区总耗散的83%和80%。     

基于数值模拟的强潮海湾潮汐预报模型精度分析：以三门湾为例

全球潮汐预报模型在深水大洋具有较高的精度, 但在近岸强潮海区由于地形岸线、模型分辨率等原因精度不一, 难以直接应用。三门湾海域多年平均潮差4 m, 最大潮差可达7 m,是典型的强潮海湾, 为了评估TPXO9.0、TPXO9.0-atlas TOPEX/POSEIDON TIDES）、NAO.99b（National Astronomical Observatory of Japan）与GTM（Global Tide Model） 4 种预报模型在三门湾海域的预报精度, 本文分别通过上述4 个潮汐预报模型提取水动力数学模型开边界进行对比,并利用提取的开边界潮位对二维水动力模型进行驱动。通过计算分析潮位站实测数据与数值模拟结果的误差, 研究4 种预报模型模拟的三门湾潮汐变化得出, NAO.99b 模型在三门湾海域整体预报精度最佳, 分潮振幅、迟角和实测数据误差最小, TPXO9.0-atlas 分潮振幅模拟较好, 但迟角误差较大。对湾内四大分潮进行潮汐调和分析发现, 三门湾海域以半日潮为主, M2、S2 和K1分潮振幅由湾顶向湾口递减, O1分潮相反。     

台湾海峡及其邻近海域潮汐数值计算

建立二维潮波模式，模拟了台湾海峡及其邻近海域（18～30°N，110～130°E）八个主要分潮（M2、S2、K1、O1、P1、Q1、K2、N2），并利用中国大陆及环台湾岛20多个潮位站的实洲资料进行验证，计算结果与实测值吻合良好。此外，给出了八个主要分潮的同潮图，并逐个讨论了潮汐特征。结果艟示：（1）台湾海峡中的潮波运动是北部蜕化了的旋转潮波系统和南部的前进潮波系统共同作用的结果。（2）半日分潮南、北两支潮波在台湾海峡中部汇合，而今日分潮则在台湾海峡南部海域汇合后继续朝西南方向传播。（3）半日分潮振幅最高值发生在福建省湄洲湾－兴化湾一带，全日分湖最高值则出现在雷州半岛以东一带近岸海域。（4）N2、K2和O1、P1、Q1分湖的振幅、迟角分布分别同M2与K1分潮的整体分布趋势相似。     

台湾海峡及其邻近海域潮汐数值计算

建立二维潮波模式,模拟了台湾海峡及其邻近海域(18-30°N,110-130°E)八个主要分潮(M2、S2、K1、O1、P1、Q1、K2、N2),并利用中国大陆及环台湾岛20多个潮位站的实测资料进行验证,计算结果与实测值吻合良好.此外,给出了八个主要分潮的同潮图,并逐个讨论了潮汐特征.结果显示:⑴台湾海峡中的潮波运动是北部蜕化了的旋转潮波系统和南部的前进潮波系统共同作用的结果.⑵半日分潮南、北两支潮波在台湾海峽中部汇合,而全日分潮则在台湾海峽南部海域汇合后继续朝西南方向传播.⑶半日分潮振幅最高值发生在福建省湄洲湾—兴化湾一带,全日分潮最高值则出现在雷州半岛以东一带近岸海域.⑷N2、K2和O1、P1、Q1分潮的振幅、迟角分布分别同M2与K1分潮的整体分布趋势相似.     

孟加拉湾陆架对潮汐的影响研究

孟加拉湾典型地形对潮汐的影响机制尚未得到深入研究,故本文基于FVCOM(finite-volume community ocean model)设置了一组控制试验和三组对照试验,通过数值试验手段理解湾顶和两侧陆架地形,以及陆架区域显著的峡谷地形对该区域潮汐的影响机制。试验结果显示:恒河峡谷有利于减小峡谷附近的潮波振幅,但对湾顶潮差影响不大;顶部陆架宽度有助于增大潮波振幅,增大湾顶的潮差;东侧陆架有助于增强开尔文波,增大湾顶潮差,但影响不如顶部的陆架显著;西侧陆架仅对西部局地有影响,对整体同潮图分布影响较小。     

福建海区的潮汐和潮流

本文根据实测资料和潮汐学基本理论,分析了福建海区潮波结构和特征、潮汐和潮流主要特征值的分布规律。结果表明,泉州湾以北海区潮汐很强,为半日潮;港湾区因受地形影响潮流很强,性质为半日潮;外海区潮流很弱,性质多为混合潮。福建南部海区潮汐很弱,性质多数是混合潮;潮流很强,性质为半日潮。     

马六甲海峡的潮汐特征分析

马六甲海峡是亚洲东南部的重要海峡通道,沟通太平洋和印度洋,具有重要的经济和战略地位.本文利用马六甲海峡及其毗邻海域验潮站的实测水位资料,分析了马六甲海峡及马来半岛东岸的潮汐特征.研究表明,半日分潮平均振幅最大的区域位于马六甲海峡内部,而全日分潮平均振幅最大的区域为马来半岛的东海岸.马六甲海峡内部以正规半日潮为主,马来半岛东侧则为混合潮港,北部为不正规全日潮,南部则为不规则半日潮.半日分潮M2,S2和全日分潮K1在马六甲海峡内的传播为自西北向东南,而全日分潮O1则为自东南向西北方向.马来半岛东岸的半日潮传播方向以中部的Cendering站为分界线,南、北两部海区分别向南、向北相背传播,而全日潮传播方向相同,统一为自北向南.     

基于FVCOM的泉州湾海域三维潮汐与潮流数值模拟

基于FVCOM海洋数值模式,采用非结构的三角形网格和有限体积法,建立了泉州湾海域高分辨率(26 m)的三维潮汐、潮流数值模型。模拟结果同2个验潮站和3个连续测流站的观测资料符合良好,较好地反映了泉州湾内潮汐、潮流运动的变化状况和分布特征,给出了M₂、S₂、K₁、O₁ 4个主要分潮的同潮图、表层潮流椭圆分布,以及模拟区域内最大可能潮差、表层最大可能潮流流速和潮余流分布。分析表明,4个分潮的最大潮汐振幅和迟角差分别为219 cm和19°,85 cm和25°,26 cm和12°,26 cm和9°;石湖港以东海域的潮波为逆时针旋转的驻波,以西海域为前进波;最大可能潮差由湾口的8.0m向湾内增加至8.8 m。湾内潮流类型为规则半日潮流,落潮最大流速大于涨潮最大流速,北乌礁水道为强流区,表层最大可能潮流流速为2.4 m/s;湾口潮流运动以逆时针方向的旋转流形式为主,湾内的潮流运动以往复流形式为主,长轴走向主要沿着水道方向,与等深线和海岸线平行;四个分潮流表层最大流速分别为1.4 m/s,0.58 m/s,0.12 m/s,0.10 m/s。余流流速大小与潮流强弱有密切的联系,表、中、底层最大余流流速分别为26 cm/s,20 cm/s,16 cm/s,三者在水平方向基本呈北进南出的分布形态。     

台湾海峡潮汐潮流的有限元模拟

本文采用三维有限元(QUODDY)模型模拟了台湾海峡的潮汐和潮流特征。模拟结果表明,有限元模型可以得到较好的模拟结果:M2,S2,O1,K1的潮位调和常数的平均绝对偏差分别为(4.18cm,7.0°),(4.68cm,11.4°),(3.52cm,7.1°)和(3.86cm,4.5°);东、北分量潮流的平均偏差M2为(10.1cm/s,29.8°)和(12.2cm/s,30.2°),而K1为(5.3cm/s,47.7°)和(5.7cm/s,49.8°)。海峡内半日潮波系统中占主导地位的是自海峡北边界传入的半日潮波。潮汐类型为正规半日潮和不正规半日潮的海区约占整个计算区域的92%以上。海峡内由四个主要分潮引起的理论最大潮差平均值为320cm,其中最大理论潮差可达681cm,出现在海峡西北部的海坛岛至兴化湾一带。     

北部湾潮汐潮流的三维数值模拟

基于二阶湍流闭合模型计算涡动粘性系数的POM三维水动力模式,采用细网格,考虑6个岛屿、海底摩擦系数进行划片取值,模拟北部湾潮汐潮流.所得潮汐调和常数与81个实测站比较,绝对平均误差:K₁分潮振幅为46cm,迟角为9°;O₁分潮振幅为56cm,迟角为7°;M₂分潮振幅为62cm,迟角为15°.由模拟结果分析出该海区潮汐、潮流、余水位和潮余流,以及水平速度垂直分布等特征.     

广西钦州湾围垦工程对茅尾海潮汐动力参数的影响

北部湾茅尾海是中国南方重要的经济开发区,兴建有滨海新城和多个港口码头,近年来围垦开发严重。本研究通过建立二维水动力数值模型系统,分析重要潮汐动力参数,对比研究1985年与2020年间钦州湾围垦和港口建设对当地水动力环境的影响。结果表明：经过围填海和港口工程之后,茅尾海的潮差变化较小,略微增加了0.05 m左右;全日分潮K1、O1及半日分潮M2、S2是影响钦州湾潮汐动力较大的驱动力,围垦后在茅尾海内海地区都略微增加了0.02~0.03 m,其中K1、O1是影响茅尾海的关键潮汐动力参数,敏感性测试分析表明三墩公路建设、钦州港海岸围垦和核电厂导堤建设对茅尾海潮差增加贡献率大致占60%、20%和10%;同时,围垦对束窄钦州湾航道具有一定的优化效应,围垦后钦州湾外湾三条水道峰值通量都明显增加,形成航道束水攻沙效果,对通航和维护主航道稳定性具有一定优势。因此,仅从潮汐动力参数变化角度分析,目前的围垦和港口工程迎合了当地河势特征,对潮汐动力场扰动较小,具有优化局部水动力场环境和提升通航安全性作用。     

大亚湾海域夏、冬季的潮汐特征及余水位与风的相关性初步探讨

大亚湾及其邻近海域冬、夏季各14个临时水位观测点1个月的实测潮位资料显示:各站的水位曲线均呈现明显的"双峰"现象,且湾顶比湾口更为明显。本文采用了调和分析方法,给出M_2、S_2、K_1、O_1四个主要分潮及M_4、M_6、2MS_6三个浅水分潮的振幅和迟角同潮图,分析大亚湾的主要潮汐特征,探讨了浅水分潮对双峰结构的贡献,并采用交叉谱分析对余水位与风的相关性进行了讨论。结果表明:(1)大亚湾海域各主要分潮振幅均由湾口向湾顶递增;高潮发生时间由湾口向湾顶推迟;涨潮历时均大于落潮历时;平均潮差在湾顶达到最大;(2)大亚湾内属于不正规半日潮,而考洲洋及其湾外海域则属于不正规全日潮;(3)大亚湾内浅水效应明显,从湾口至湾顶,六分之一日分潮的振幅呈5—7倍的增长,主导了大亚湾潮波系统的形变;(4)分潮重构结果显示,四分之一日和六分之一日浅水分潮(尤其是2MS_6分潮)的异常增长,是导致大亚湾潮汐双峰现象的主要原因;(5)冬季大亚湾内各点的余水位与风速呈现正相关,相关系数均在0.53以上;(6)周期为0.45—0.53 d的沿岸风对各站余水位的影响最大。     

Application of a two-dimensional depth-averaged hydrodynamic tidal model

A two-dimensional hydrodynamic model application to the San Francisco Bay was performed using the Boundary-Fitted HYDROdynamic model (BFHYDRO). The model forcing functions consist of tidal elevations along the open boundary and fresh water flows from the Delta Outflow. The model-predicted surface elevations compare well with the observed surface elevations at five stations in San Francisco Bay. Mean error in the model predicted surface elevations and currents are less than 7 and 9%, respectively. Correlation coefficients for surface elevations and currents are higher than 0.94 and 0.95, respectively. The amplitudes and phases of the principal tidal constituents at 24 tidal stations in San Francisco Bay, obtained from a harmonic analysis of a 90-day simulation compare well with the observed data. The predicted amplitude and phase of the M₂ tidal constituent at these stations are respectively within 8 cm and 8° of the observed data. Maximum errors in the K₁ harmonic amplitudes and phases are less than 3 cm and 7° respectively. The asymmetric diurnal and semi-diurnal tidal ranges and spring and neap tidal cycles of the surface elevations and currents are well reproduced in the model at all stations.     

Evidence for predominance of internal tidal currents in Sagami and Suruga bays

Tidal currents observed in a surface layer overlying deep water in Sagami and Suruga Bays frequently have large amplitude in summer and fall. Numerical experiments show that the current amplitude due to the surface tides is below 1.0 cm sec^–1 for the semidiurnal and diurnal constituents in the inner region of the two bays. The observed current amplitudes are larger than the calculated ones due to the surface tides. Therefore, the observed tidal currents are indicated to be due mainly to the internal tides. In addition, the semidiurnal currents dominate the diurnal currents in Sagami Bay, while the opposite occurs in Suruga Bay. These results suggest that the prevailing periods of the internal tides differ between the two bays,i.e., the internal tide has a semidiurnal period in Sagami Bay and a diurnal period in Suruga Bay.     

Variations of the age of tides in the global oceans

Abstract

Earlier studies on the age of tide dealt mostly with the age of the semi‐diurnal tide in the Atlantic and Pacific Oceans. In these studies, the variations of the age of tide were determined making use of recorded tidal data up to and including the 1960s. In the present study, all available tidal data till the mid 1980s are utilized and the computations were done for the four global oceans: Atlantic, Pacific, Indian, and Arctic. Also, in addition to the age of the semi‐diurnal tide, the age of the parallax and the age of the diurnal tide were determined. The distribution patterns for the positive and negative ages for the semi‐diurnal tide, parallax, and diurnal tide were related whenever possible with the tidal amphidromic point locations and the amplitude ratios S₂/M₂, N₂/M₂, and O₁/K₁.     

杭州湾开挖深水航道对潮流影响的数值研究

采用ｘ方向伸展坐标下的二,三维方程,建立了开避或增深深水航道前后的潮流场数值模模式。该模式在航道横向上网格变距,以保证航道横向上有一定量的网格覆盖。在计算中采用二,三维交替进行,既节省大量计算时间,又保证了计算的稳定性。     

Circulation pattern and current variations with respect to tidal frequency in the sea near the head of Suruga Bay

Current measurements were conducted 10 m below the sea surface near the head of Suruga Bay intermittently from 1970 to 1978. The circulation pattern is usually counterclockwise; northward along the east coast (off Heda and at the mouth of Uchiura Inlet), westward along the north coast (off Fuji), and southwestward along the west coast (off Shimizu). The amplitudes of the four major tidal constituents of current variation, M₂, S₂, K₁ and O₁, are much larger than those expected from sea level variations along the coast. The amplitudes of the diurnal constituents of current variation are much larger than those of the semidiurnal constituents, while the amplitudes of the semidiurnal constituents of sea level variation are much larger than those of the diurnal constituents. The observed amplitude of the predominant diurnal constituents exhibit large seasonal changes and tend to increase with the development of the stratification of the upper part of the water in Suruga Bay. These facts strongly suggest that the observed current variations are mainly associated with internal tides in Suruga Bay.     

Difference in the prevailing periods of internal tides between Sagami and Suruga Bays: Numerical experiments

Current measurements in the surface layer in Sagami and Suruga Bays showed existence of significant tidal currents which are considered to be mainly due to internal tides (Inaba, 1982; Ohwaki,ea al., 1991). In addition, the prevailing period of the tidal currents is semidiurnal in Sagami Bay, but diurnal in Suruga Bay. To explain this difference in the prevailing, periods, numerical experiments were carried out using a two layer model. The internal tides are generated on the Izu Ridge outside the two bays. The semidiurnal internal tide propagates into Sagami Bay having characteristics of an internal inertia-gravity wave, while it propagates into Suruga Bay having characteristics of either an internal inertia-gravity wave or an internal Kelvin wave. The diurnal internal tide behaves only as an internal Kelvin wave, because the diurnal period is longer than the inertia period. Thus, the diurnal internal tide generated on the Izu Ridge can be propagated into Suruga Bay, while it cannot propagate into the inner region of Sagami Bay, though it is trapped around Oshima Island, which is located at the mouth of Sagami Bay. The difference in the propagation characteristics between the semidiurnal and diurnal internal tides can give a mechanism to explain the difference in the prevailing periods of the internal tides between Sagami and Suruga Bays.