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1.
北黄海定点连续观测站海流资料分析 总被引：2，自引：0，他引：2
本文利用2009年6月至11月期间的ADCP海流资料,研究了獐子岛附近一个固定观测点处的时间平均流及潮流特征。结果表明,该海区的平均流大致沿等深线方向,从黄海流向渤海,整个观测期间纬向平均流大于经向平均流,经向1m宽度范围内的纬向净水体输运量为0.67m3/s,而纬向1m宽度内的经向净水体输运量为0.16m3/s;垂向上可以15m和47m为节点分为三层,15m大致为温跃层深度,而47m以下为底摩擦影响显著的范围。夏季的温盐层化结构对于余流的垂直分布存在显著影响。潮流调和分析表明,该海区的潮汐类型为正规半日潮,M_2和K_1分潮在整个深度范围内的平均振幅分别为27.9cm/s和9.2cm/s,半日潮流由表及底均为旋转流,而全日潮流更趋向于往复流。在垂向上,各个分潮的潮流椭圆均随深度发生小幅度的旋转,半日潮流椭圆随深度逆时针旋转,倾角变化小于30°,全日潮流椭圆随深度顺时针旋转,倾角变化小于40°。潮流在近底层受到底摩擦的影响十分显著,其中全日潮流受到底摩擦的影响较半日潮流大。本次观测是进一步研究北黄海区域潮流、近惯性流动与水体交换输运的直接参考,其结果加深了对该区域流场特性的认识和理解。 相似文献
2.
琼州海峡夏季三塘潮流谱分析和余流特征研究 总被引：3，自引：0，他引：3
无论潮流矢量是反时针旋转(f>0)还是顺时针旋转(f<0),全日潮谱峰都高于半日潮谱峰。2个半日潮周期分别为12、12.4h;2个日潮周期分别为23.9和25.8h;在半日潮和全日潮分量中,反时针分量是主要的:顺时针的半日潮能谱只有反时针的84%;顺时针的日潮能谱只有反时针的65%;浅水分潮6.2、8h和超过24h的3、4.2和5.5d等也有明显表现,但是都未通过显著性检验;夏季余流流速在5～10cm/s范围内变化,方向以南偏西为主。造成这种现象的首要的因素是夏季琼州海峡水交换基本态势和三塘附近海底地形,风对流向变化也有重要影响。 相似文献
3.
《中国海洋大学学报(自然科学版)》2017,(5)
利用广西近岸西部白龙半岛海域2011—2012年连续一年的观测资料和数值计算方法,研究了该海域潮流和余流的基本特征及变化规律,得出如下结论:白龙半岛海域潮汐为正规全日潮,但是潮流为不规则半日潮流;旋转谱分析显示,潮流逆时针旋转分量强于顺时针旋转分量,全日潮流的总能量小于半日潮流的能量;潮流振幅在夏季明显高于冬季,这是因为夏季北部湾北部的显著层结导致的较浅海域的内潮同样比较显著,并且表现为由表层向底层加强;另外,本文首次发现,经过北部湾的台风会增强主要的全日、半日分潮的能量,引起潮流的流速增加。通过数模试验,第一次发现在白龙半岛附近海域存在一个小尺度的反气旋涡,范围大约位于108°E~108.7°E、20.8°N~21.5°N,涡旋在秋季产生,可以一直持续到冬季结束。 相似文献
4.
根据夏季琼州海峡新海附近15 m处地层潮流谱分析结果可得,无论是f>0 或f<0,全日潮谱峰都高于半日潮谱峰。其中,半日潮周期,约为12 h,12.4 h,日潮存在两个,一个在23.9 h,另一个在25.8 h前后;在半日潮和全日潮分量中,反时针分量是主要的、顺时针的日潮能谱只有反时针的84%;顺时针的半日潮能谱只有反时针的63%;浅水分潮8.3 h,6.2 h和超过24 h的4.2 d,3 d等也很明显,但是未通过显著性检验; 大多数余流流速在5~10 cm/s之间,个别情况超过40 cm/s。受反时针运动涡旋影响,余流主要向偏东北、北、西北方向运动。在这个区间内的流向,占总观测数68%以上;风对余流也有重要影响:东北风将使余流方向偏向西北,偏北向风将使余流方向偏南。 相似文献
5.
根据夏季琼州海峡新海附近15 m处地层潮流谱分析结果可得,无论是f>0 或f<0,全日潮谱峰都高于半日潮谱峰。其中,半日潮周期,约为12 h,12.4 h,日潮存在两个,一个在23.9 h,另一个在25.8 h前后;在半日潮和全日潮分量中,反时针分量是主要的、顺时针的日潮能谱只有反时针的84%;顺时针的半日潮能谱只有反时针的63%;浅水分潮8.3 h,6.2 h和超过24 h的4.2 d,3 d等也很明显,但是未通过显著性检验; 大多数余流流速在5~10 cm/s之间,个别情况超过40 cm/s。受反时针运动涡旋影响,余流主要向偏东北、北、西北方向运动。在这个区间内的流向,占总观测数68%以上;风对余流也有重要影响:东北风将使余流方向偏向西北,偏北向风将使余流方向偏南。 相似文献
6.
利用旋转谱分析、调和分析和低通滤波的方法,对1987年8月至1988年1月南海北部东沙附近陆架坡折带处定点海流观测资料进行分析,研究了该区域定常余流、潮流和低频流的特征。各观测层次定常余流基本为西向流,垂向呈现较强的正压性。潮流以日分潮和半日分潮为主,呈顺时针方向旋转,全日潮流椭圆长轴普遍大于半日潮流,冬季K1分潮振幅在近底层明显增大,海流在中间层存在明显的惯性振荡。从能量角度分析,剩余流占海流总能量比例较大,定常余流能量主要存在于沿岸线方向,而垂直于岸线方向的能量主要由潮流和剩余流构成。低频流存在显著的季节变化,1988年1月呈现明显的顺时针旋转形态。冬季海表面风应力与次表层低频流有较强的相关性。结合OFES(Ocean General Circulation Model for the Earth Simulator)模拟结果,利用动量平衡分析的方法探究了动量方程中各项对低频流的贡献以及1988年1月次表层出现北向流的动力机制。冬季低频流具有较强的地转流特征,垂向分布受海水层化影响;东北风松弛和反气旋涡的联合作用是次表层出现偏北向流动的主要原因。 相似文献
7.
夏季长江口外东海海域实测海流资料分析 总被引：2，自引：0，他引：2
根据2009年8,9月间长江口外海域C1,B1 2个站位的短期连续ADCP实测资料,采用调和分析、EOF分解、功率谱分析以及频率统计等方法,分析了该海域海流随时间的变化趋势和空间的结构特征。结果表明,2个站位流速在观测期间愈来愈强,准定常流动均是南向流动占优。长江口外海域M2为主要分潮,属于正规半日潮,各层潮流呈现出旋转流性质,旋转方向为顺时针占优。2个站位潮流的U,V分量均为第一模态主导,其垂向模态基本一致,体现了潮流的正压特征,2个站位的斜压性均不明显。海流的流速、流向频率统计显示两站均在SSE,S,SSW方向的频率最大。 相似文献
8.
基于FVCOM的獐子岛附近海域三维潮汐潮流数值模拟 总被引：1，自引：1，他引：0
基于采用不规则三角网格的海洋模型FVCOM(An Unstructured Grid, Finite Volume Coastal Ocean Model), 对獐子岛附近海域的潮汐、潮流进行了精细化数值模拟研究, 模拟的潮汐、潮流与实测值符合良好, 表明建立的该海域精细化潮汐潮流数值模型合理可靠。依据计算结果绘制了M2、S2、K1和O1分潮的同潮图和潮流椭圆图, 并对该海域潮汐潮流特征进行了系统分析。结果表明, 獐子岛附近海域的潮汐主要以规则半日潮为主, 水平潮流多为旋转流, 旋转方向大部分为逆时针; 近岸海区和水道之间多为往复流, 在大鹿岛以南海域也存在一往复流的区域。在123.75°E以东存在一顺时针旋转的区域。由潮余流场的特点可看出, 獐子岛等各岛屿周围均形成气旋式的绕岛流, 流速一般位于8—12cm/s之间, 离岸线较远的外海区域余流较小, 只有1—2cm/s。本文所得结论, 有助于增加对整个獐子岛海域潮汐潮流特性的全面认识。 相似文献
9.
利用2014年各月浮标观测得到的表层海流资料,对其进行调和分析,基于调和分析结果对渤海中部潮流和余流特征进行研究。结果表明:渤海中部大部分海域潮流性质属于不正规半日潮性质。渤海中部水深较浅,浅水分潮的影响不可忽略,其中M4分潮的影响更为显著;潮流运动形式除西部和北部两个浮标点为往复流以外其余均是旋转流,旋转方向均为逆时针;渤海中部实测涨落潮流除最北端的2号浮标点较强以外,其他均小于75 cm/s。涨落潮流的强度较一致。渤海中部的余流除4号浮标点以外均为偏向北的流动,表层月均余流的季节变化不太明显。本文推测渤海中部环流的流动特征为顺时针。冬季渤海中部表层余流受制于风的作用,春、夏季某些区域余流受到风的影响较大,是潮汐余流和浅海风海流的合成。而靠近岸边的1号浮标点以潮余流为主。 相似文献
10.
利用2008年夏季和冬季的海流资料分析了红海湾西北海区潮流性质、运动形式、涨落潮流特性、余流特征。结果表明: 红海湾西北海区属不规则半日潮海域, 潮流性质属往复流, 大致呈东—西向往返运动, 具有一定的旋转流性质; 平均涨潮流最大可达17.8cm·s-1, 平均退潮流最大可达19.3cm·s-1; 实测流受风和地形影响明显。余流受风和地形的影响也比较明显, 在偏北风作用下, 余流流向西偏南; 在偏南风作用下, 余流流向东偏北, 余流最大可达18.9cm·s-1。潮能主要由东部向西传播至红海湾西北海区, 潮能进入量值可达4.8×103W·m -1。 相似文献
11.
关于海洋中的正压流和斜坛流的概念，目前存在着３种不同的提法．本文首先分别简述它们在定义上的差别，然后对３种定义在理解海流性质问题上的长、短处加以评述。一些理论物理海洋学家依据地转关系式，把与海面倾斜相连系的流视为正压流部分，而与密度不均匀性有关的视为斜压流部分。笔者认为这种定义在物理概念上是清楚，在实际应用中是方便，因此在讨论海流性质时最好采用这种观点。 相似文献
12.
太平洋北赤道流表层流速及分叉点位置 总被引：3，自引：0，他引：3
确定太平洋北赤道流表层流速及分叉点位置的变化是海洋环境研究中的1个重要问题。使用1987～1998年的WOCE浮标资料,通过估算得到了季节平均和年平均意义下北赤道流表层流速(1989～1998)。计算结果显示:北赤道流表层流的流速冬季最大,夏季最小,春秋两季相仿。在厄尔尼诺发生年的第2年,夏季平均流速往往较大。对浮标轨迹的逐年分析表明表层北赤道流分叉点的位置在11°N～14 .7°N之间,从轨迹较为密集的4年的分析可以看出,表层流分叉点的位置具有年际变化,其中,2个ElNino年分叉点偏北。 相似文献
13.
Masaji Matsuyama Makiko Wadaka Taizo Abe Masaaki Aota Yoshio Koike 《Journal of Oceanography》2006,62(2):197-205
ADCP, CTD and XBT observations were conducted to investigate the current structure and temperature, salinity and density distributions
in the Soya Warm Current (SWC) in August, 1998 and July, 2000. The ADCP observations clearly revealed the SWC along the Hokkaido
coast, with a width of 30–35 km and an axis of maximum speed of 1.0 to 1.3 ms−1, located at 20–25 km from the coast. The current speed gradually increased from the coast to a maximum and steeply decreased
in the offshore direction. The SWC consisted of both barotropic and baroclinic components, and the existence of the baroclinic
component was confirmed by both the density front near the current axis and vertical shear of the alongshore current. The
baroclinic component strengthened the barotropic component in the upper layer near the axis of the SWC. The volume transport
of the SWC was 1.2–1.3 SV in August, 1998 and about 1.5 SV and July, 2000, respectively. Of the total transport, 13 to 15%
was taken up by the baroclinic component. A weak southeastward current was found off the SWC. It had barotropic characteristics,
and is surmised to be a part of the East Sakhalin Current. 相似文献
14.
Masaki Kawabe 《Journal of Oceanography》1986,42(4):319-332
I summarize the variations of the path of the Kuroshio and of the Tsushima Current mainly based on the results of my studies. The Tsushima Current forms three branches just after it enters the Japan Sea through the Tsushima Strait. The first and third branch currents flow along the Japanese and Korean coasts, respectively, and the second branch current flows from the western channel of the Tsushima Strait to the west of the Oki Islands only in summer from June to August. Properties of the topographic waves which are thought to work on the formation of the second branch are described mainly in terms of the dispersion relations. The Kuroshio has three typical paths,i.e., the nearshore and offshore non-large-meander paths and the typical large-meander path. The Kuroshio alternately takes the nearshore and offshore paths in the non-large-meander period, occasionally changes from the nearshore nonlarge-meander path to the large-meander path and, after having taken the large-meander path for several years, changes to the offshore non-large-meander path. Sea levels south of Japan are clearly different between the non-large-meander and large-meander periods, while they are not different between the periods of the nearshore and offshore non-large-meander paths. But, sea level and water properties in the coastal region show remarkable features during short periods of transitions between the typical non-large-meander paths. Future problems and subjects of studies on these currents are indicated. Especially, importance of velocity monitoring of the Kuroshio is emphasized, and a design of the observation across the Tokara Strait is proposed. 相似文献
15.
The branching of the Tsushima Warm Current (TWC) along the Japanese coast is studied based upon intensive ADCP and CTD measurements
conducted off the Wakasa Bay in every early summer of 1995–1998, the analysis of the temperature distribution at 100 m depth
and the tracks of the surface drifters (Ishii and Michida, 1996; Lee et al., 1997). The first branch of TWC (FBTWC) exists throughout the year. It starts from the eastern channel of the Tsushima Straits,
flows along the isobath shallower than 200 m along the Japanese coast and flows out through the Tsugaru Strait. The current
flowing through the western channel of the Tsushima Straits feeds the second branch of TWC (SBTWC) which develops from spring
to fall. The development of SBTWC propagates from the Tsushima Straits to Noto Peninsula at a speed of about 7 cm sec−1 following the continental shelf break with a strong baroclinicity. However, SBTWC cannot be always found around the shelf
break because its path is influenced by the development of eddies. It is concluded that SBTWC is a topographically steered
current; a current steered by the continental shelf break. Salient features at intermediate depth are the southwestward subsurface
counter current (SWSCC) between 150 m and 300 m depths over the shelf region in 1995–1998 with the velocity exceeding about
5 cm sec−1, although discrepancies of the velocity and its location are observed between the ADCP data and the geostrophic currents.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
16.
Mooring and hydrographic observations were conducted from September 2012 to May 2014 at the mouth of Otsuchi Bay, a ria along the Pacific coast of Japan. Our observations quantitatively demonstrated that the circulation and the water properties of Otsuchi Bay are strongly influenced by the Tsugaru Warm Current (TWC) and Oyashio Current (OY) at seasonal and subseasonal time scales. Two bottom-mounted velocity profilers and temperature and salinity measurements beneath the near-surface halocline showed a counterclockwise lateral circulation pattern related to the TWC, which was enhanced from summer to autumn. From winter to early spring, the lateral circulation patterns related to the TWC weakened and the influence of the OY occasionally increased. When the OY was weak, surface flows became an overturning structure, with outflows in the upper layer and inflows in the lower layer. When the OY was strong and passed close to the Sanriku coast, the circulation became highly variable and intermittent. Intrusions of the markedly low-salinity OY water were observed on two occasions and persisted for periods of several weeks to several months. Salinity was sometimes less than 33.7, the lower limit of the typical TWC from late summer to autumn even when the TWC dominates. We suggested that this is the seasonal fluctuations of the TWC itself, as the upstream current of the Tsushima Warm Current is freshened in summer as a result of the influence of the Changjiang River. The surface water was generally fresher in the south of the bay than in the north, suggesting the Coriolis deflection of the river plume. 相似文献
17.
The California Current System (CCS) is forced by the distribution of atmospheric pressure and associated winds in relation to the west coast of North America. In this paper, we begin with a simplified case of winds and a linear coast, then consider variability characteristic of the CCS, and conclude by considering future change. The CCS extends from the North Pacific Current (～50°N) to off Baja California, Mexico (～15–25°N) with a major discontinuity at Point Conception (34.5°N). Variation in atmospheric pressure affects winds and thus upwelling. Coastal, wind-driven upwelling results in nutrification and biological production and a southward coastal jet. Offshore, curl-driven upwelling results in a spatially large, productive habitat. The California Current flows equatorward and derives from the North Pacific Current and the coastal jet. Dominant modes of spatial and temporal variability in physical processes and biological responses are discussed. High surface production results in deep and bottom waters depleted in oxygen and enriched in carbon dioxide. Fishing has depleted demersal stocks more than pelagic stocks, and marine mammals, including whales, are recovering. Krill, squid, and micronekton are poorly known and merit study. Future climate change will differ from past change and thus prediction of the CCS requires an understanding of its dynamics. Of particular concern are changes in winds, stratification, and ocean chemistry. 相似文献
18.
From 1988 to 1993, 23 satellite-tracked drifting buoys entered the Kamchatka Current. The buoy trajectories showed a well-formed, high-speed current that originated near Shirshov Ridge, and flowed southward through Kamchatka Strait. During some years, the buoys turned eastward at 50°N, while in other years they were transported as far south as Japan (40°N). Only one buoy entered the Sea of Okhotsk. Eddies were evident in many of the buoy trajectories. Greatest maximum daily velocities (>100 cm s–1) were observed south of Kamchatka Strait, with 50–60 cm s–1 being more common. 相似文献
19.
20.
《Ocean Modelling》2011,39(3-4):251-266
Results are presented from an ensemble prediction study (EPS) of the East Australian Current (EAC) with a specific focus on the examination of the role of dynamical instabilities and flow dependent growing errors. The region where the EAC separates from the coast, is characterized by significant mesoscale eddy variability, meandering and is dominated by nonlinear dynamics thereby representing a severe challenge for operational forecasting. Using analyses from OceanMAPS, the Australian operational ocean forecast system, we explore the structures of flow dependent forecast errors over 7 days and examine the role of dynamical instabilities. Forecast ensemble perturbations are generated using the method of bred vectors allowing the identification of those perturbations to a given initial state that grow most rapidly. We consider a 6 month period spanning the Austral summer that corresponds to the season of maximum eddy variability. We find that the bred vector (BV) structures occur in areas of instability where forecast errors are large and in particular in regions associated with the Tasman Front and EAC extension. We also find that very few BVs are required to identify these regions of large forecast error and on that basis we expect that even a small BV ensemble would prove useful for adaptive sampling and targeted observations. The results presented also suggest that it may be beneficial to supplement the static background error covariances typically used in operational ocean data assimilation systems with flow dependent background errors calculated using a relatively cheap EPS. 相似文献