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1.
根据中、日合作黑潮调查研究期间（1987－1993年）在九州西侧海域获得的水文资料，计算了129°E断面的地转流速和流量。着重提出129°E断面北侧存在一支较稳定的西向流；分析这支西向流的去向，指出它是向对马暖流输送黑潮水的重要途径；给出了这支西向流及黑潮通过该断面的流速、流轴、流幅及流量的变化特征。 相似文献
2.
台湾以东黑潮流量的年际变化特征 总被引：13，自引：2，他引：13
利用长时间序列的石垣和基隆两个验潮站的海平面高度记录(18年)计算了台湾以东的黑潮流量，并结合风应力资料(SODA)，探讨了台湾以东黑潮流量的年际变化及其和风应力旋度的关系。台湾以东黑潮流量的峰值出现在1980—1981、1982—1983、1986、1988及1991年。低值出现在1984、1990、1993—1995年。小波分析结果显示，台湾以东黑潮流量具有2—5年的显著周期(峰值在2年和5年)；台湾以东北太平洋区域风应力旋度具有2—7年的显著周期(峰值在3年和6年)。在1980—1991年间，黑潮大弯曲频繁发生，台湾以东黑潮流量偏大，与台湾以东太平洋区域风应力旋度间的关系较好；而在1991—1995年间，没有黑潮大弯曲发生，台湾以东黑潮流量偏低，与台湾以东太平洋区域风应力旋度间的关系较差。 相似文献
3.
日本南部黑潮路径变异对北太平洋地区的气候和环境具有显著的影响,对黑潮路径变异的研究具有重要的意义。本文利用POM(Princeton Ocean Model)数值模式模拟了日本南部黑潮的路径变异情况,分析了黑潮大弯曲路径形成的可能机制。研究结果表明,当黑潮处于非大弯曲路径时,相对位势涡度的平均值呈现递减趋势,说明日本南部低位势涡度水在不断积累,这样会使得四国再循环流的强度增强,迫使黑潮保持平直路径,同时,近岸黑潮垂直流速剪切增大,斜压不稳定性的作用也逐渐增大;当黑潮从非大弯曲路径向大弯曲路径过渡时,再循环流强度的减弱会导致黑潮的流速剪切减小。根据海表高度异常场以及海洋上层流场信息发现,近岸黑潮附近的气旋涡会随着再循环流区域反气旋涡的东侧向南运动,最终导致黑潮大弯曲的发生。分析涡流的能量,结果显示,黑潮大弯曲路径的形成与斜压不稳定性密切相关。 相似文献
4.
黑潮延伸体海域海平面年际变化及其与海流的关系 总被引：1，自引：0，他引：1
利用黑潮延伸体海域海平面异常(SLA)数据和SODA海流资料,分析海平面和海流的年际变化特征,以及两者之间的关系。分析发现黑潮延伸体SLA的第二模态是黑潮大弯曲模态,存在29个月的准两年显著振荡。该海域海平面具有显著的年际变化,且与ENSO和PDO密切相关,2002-2004年的黑潮大弯曲期间,海平面与Nino3指数的相关系数为0.74。海平面年际变化和海流关系密切,黑潮延伸体主轴两侧海平面具有显著的季节和年际变化,急流呈大弯曲路径(1993-1996、2002-2004)时,流轴稳定流速大,流轴影响深,急流主轴南侧海平面较高,达到年际变化的最大值,主轴两侧海面高度梯度大。非弯曲期间,急流主轴南压,海流强度减弱,此期间海平面低,主轴两侧海面高度梯度较小。黑潮延伸体上游区海平面变化受黑潮大弯曲影响更为显著。上下游区的海平面和比容海平面的年际变化较为相似,黑潮延伸体海域海流和比容效应共同调控该区域海平面变化。 相似文献
5.
6.
过去的研究认为,黑潮延伸体的年代际振荡受来自其下游的太平洋年代际振荡（PDO）相关联的信号主导,但最近的观测表明这种调控机制在2017年9月之后不再成立。与此同时,黑潮延伸体的上游即日本南部黑潮正在发生一次大弯曲事件。利用26年（1993–2018年）的卫星高度计提供的海表高度距平数据和自组织映射（SOM）方法,本文研究了日本南部黑潮与黑潮延伸体的时空模态及其因果关系。结果表明,SOM能有效地提取两个海区的典型空间模态,且它们的演变轨迹表明当日本南部黑潮处于大弯曲（离岸型非大弯曲）路径时,黑潮延伸体趋于稳定（不稳定）态。基于SOM识别得到的海表面高度距平（SLA）特征区及特征时间模态,我们进一步利用一种最近发展的定量因果分析方法研究了两个流系之间的因果关系。研究发现,当黑潮大弯曲发生时,日本南部黑潮和黑潮延伸体之间存在双向因果,但因果关键区不同。前者对后者的影响集中在纪伊半岛东南侧及黑潮延伸体“两脊一槽”区域,而后者对前者的影响则集中在黑潮延伸体“两脊一槽”区域及黑潮再循环流区域。这说明黑潮大弯曲的发展对黑潮延伸体的稳定性有重要作用,同时黑潮延伸体通过调制南部再循环流影响日本南部黑潮的路径。不同的是,当离岸型非大弯曲路径发生时,只有从日本南部黑潮向黑潮延伸体的单向因果关系,且因果性主要集中在伊豆海脊及再循环流区域。这与该时期海表高度负异常沿日本南岸不断向位于下游的黑潮延伸体再循环流的传播有关,它使得黑潮延伸体变得不稳定。 相似文献
7.
本文运用简化的η坐标POM模式研究了东海黑潮锋面弯曲的产生与成长机制。主要考察了在给定的地形下，流核位置和流量变化对锋面演变的影响。当黑潮流核远离陆架时，因其锋区正好在陡的陆坡之上，斜压不稳定贡献减小，此时不论黑潮的流量强弱，其锋面都不会出现如观测所示的弯曲；当黑潮流核接近陆架时，因其锋区爬上陆架，斜压不稳定加强，小扰动能够充分发展并导致锋面弯曲，它的三维结构和观测的结果基本一致。平均波长约为250km，位相速度约为17km／d。扰动成长的主要机制是斜压不稳定，锋面弯曲的主要能源是平均有效位能。 相似文献
8.
PN断面黑潮流速垂直分布特征及机制分析 总被引：1，自引：0，他引：1
基于全球海洋再分析模拟GLORYS2(Global Ocean Reanalysis Simulation 2)结果,分析了PN断面(126.0°E-128.2°E,1 000 m以浅)黑潮流速垂直结构的季节和年际变化,探讨了黑潮流速垂直结构形成的动力学机制。结果表明:1)PN断面黑潮夏季流量最大,春季次之,秋、冬季节最小;气候态平均的冬、夏季流速最大值都位于次表层,春、秋季节流速最大值位于表层;夏季相对流速较大、最大值深度较浅;等密线在黑潮主轴区下凹,冬季更为明显。流速最大值深度和密度水平梯度为零的深度均表现出了较大的年际差异,该年际变化甚至超过季节差异;2)流速与密度符合热成风关系。黑潮通量由太平洋大尺度风场及中尺度运动两者共同决定,但局地的热通量和环流对温盐的输运共同影响密度场,调节黑潮流速的垂直分布,影响水通量的分配及营养盐输运;3)有些年份夏季流速最大值出现在表层,可能是夏季西南季风诱导陆架水离岸输运进入黑潮上层导致的结果。非线性、非地转物理过程的影响没有考虑在本研究中,热成风关系能够解释黑潮流速垂直分布形成的部分原因。 相似文献
9.
《海洋通报(英文版)》2015,(1)
本文基于全球海洋再分析模拟GLORYS2(Global Ocean Reanalysis Simulation 2)结果,分析了PN断面(126.0°E-128.2°E,1 000 m以浅)黑潮流速垂直结构的季节和年际变化,探讨了黑潮流速垂直结构形成的动力学机制。结果表明:1)PN断面黑潮夏季流量最大,春季次之,秋、冬季节最小;气候态平均的冬、夏季流速最大值都位于次表层,春、秋季节流速最大值位于表层;夏季相对流速较大、最大值深度较浅;等密线在黑潮主轴区下凹,冬季更为明显。流速最大值深度和密度水平梯度为零的深度均表现出了较大的年际差异,该年际变化甚至超过季节差异;2)流速与密度符合热成风关系。黑潮通量由太平洋大尺度风场及中尺度运动两者共同决定,但局地的热通量和环流对温盐的输运共同影响密度场,调节黑潮流速的垂直分布,影响水通量的分配及营养盐输运;3)有些年份夏季流速最大值出现在表层,可能是夏季西南季风诱导陆架水离岸输运进入黑潮上层导致的结果。非线性、非地转物理过程的影响没有考虑在本研究中,热成风关系能够解释黑潮流速垂直分布形成的部分原因。 相似文献
10.
西北太平洋黑潮路径变化与柔鱼CPUE的关系研究 总被引：7，自引：0，他引：7
利用西北太平洋长时间序列SST、黑潮路径、柔鱼渔获量数据,基于GIS技术分析了黑潮路径类型变化和离岸摆动及其对柔鱼CPUE的影响。分析结果表明,1990—2003年,黑潮弯曲发生的月份数占82％,其中整月发生弯曲的月份数占47％,共发生2次大弯曲、2次准弯曲、5次小弯曲。柔鱼年CPUE,在黑潮发生准弯曲年份最高,黑潮发生小弯曲年份较高,黑潮发生大弯曲年份和平直年份较低,黑潮大弯曲发生的强盛年份最低。柔鱼月CPUE高值时段,多是黑潮发生弯曲时段,且主要是C型弯曲。连续3月以上出现月CPUE高值段,黑潮路径模式是C型弯曲和平直路径交替出现。3天CPUE的高值时段,黑潮弯曲型的频次远高于平直型;较高值时段,黑潮弯曲型的频次稍高于平直型;中值时段,黑潮平直型频次稍高于弯曲型;较低值时段,黑潮平直型高于弯曲型;低值时段,黑潮平直型远高于弯曲型。 相似文献
11.
Detecting fluctuations of the Kuroshio axis south of Japan using TOPEX/POSEIDON altimeter data 总被引：1，自引：0，他引：1
Shiro Imawaki Mayumi Gotoh Hiroyuki Yoritaka Noriya Yoshioka Atsunobu Misumi 《Journal of Oceanography》1996,52(1):69-92
Sea surface dynamic topography (SSDT) can be divided into temporal mean SSDT and fluctuation SSDT. The former is approximated with a climatological mean SSDT and the latter is derived from satellite altimetry data, to give an approximated total SSDT (called a composite SSDT). The method is applied to detecting fluctuations of the Kuroshio axis south of Japan using TOPEX/POSEIDON altimeter data from the first year mission in 1992–1993. The fluctuation SSDT averaged over a wide area south of Japan clearly shows an annual cycle with an amplitude of about 15 cm. Temporal changes of SSDT along a subsatellite track crossing the Kuroshio compare moderately well with those estimated from repeated hydrographic observations, although there is a discrepancy of unknown origin. The composite SSDT also compares well with SSDT estimated from the same hydrographic data. Horizontal distribution of the surface geostrophic velocity component normal to subsatellite tracks is derived every ten days from the composite SSDT. Most locations of estimated strong eastward geostrophic velocities coincide well with locations of the Kuroshio axis determined every 15 days fromin situ surface velocity measurements on various vessels; for example, a fairly large meander of the Kuroshio south of Honshu is clearly detected. It is concluded that the composite SSDT can be used reliably to detect fluctuations of the Kuroshio axis south of Japan. 相似文献
12.
Surface velocities determined from trajectory of a drifting buoy from March through November 1987 are compared with surface geostrophic velocities determined from sea surface dynamic topography (SSDT) obtained from altimetry data with the aid of long-term hydrographic observation data. In general, these velocities show similar temporal variations in both zonal and meridional components, except in a period when obvious error is found in the altimetric SSDT field. When the buoy was trapped by several mid-ocean meso-scale eddies, the comparison is especially good. Systematic discrepancy is found, however, when the buoy was in the Kuroshio region, because of using both temporally and spatially smoothed mean SSDT estimated from hydrographic data; instead, surface geostrophic velocities determined from the altimetric SSDT referred to the improved geoid model result in better comparison. 相似文献
13.
由于卫星高度计数据分辨率高、观测范围广的特点，我们使用该数据开展了黑潮流的研究。在之前的研究中，卫星绝对地转流都被用于对黑潮流域的表层流场的时空变化特征进行研究，并采用了一些探测方法提取了黑潮流轴和流路。然而，海面绝对地转流是由绝对动力地形估计得到，应该被当做实际流场的地转分量，在实际应用中并不能代表真实流场。在本研究中，建立了气候态绝对地转流与网格平均的漂流浮标流场间的数学校验关系，以此对卫星绝对地转流场进行修正，即便这两种数据的性质存在些许偏差。因此，基于主成分探测法，修正后的卫星绝对地转流被用于探测黑潮流轴和流路。对比结果表明，由修正后的卫星地转流场探测得到的黑潮流轴和流路均要好于地转流和表层流估计结果。修正后的地转流有助于开展更加准确的黑潮流轴和流路的逐日探测。 相似文献
14.
Kaoru Ichikawa 《Journal of Oceanography》2001,57(1):55-68
Temporal variations of the Kuroshio volume transport in the Tokara Strait and at the ASUKA line are decomposed by phase-propagating Complex EOF modes of high-resolution sea surface dynamic topography (SSDT) field during the first tandem period of TOPEX/POSEIDON and ERS-1 (from October 1992 to December 1993). Both variations are dominated by a mode with nearly semi-annual cycle, which indicates a series of interactions between the Kuroshio and meso-scale eddies. Namely, northern part of a westward-propagating meso-scale eddy at 23°N is captured into the southern side of the Kuroshio at the south of Okinawa, then it moves downstream along the Kuroshio path passing the Tokara Strait, and reaches to the ASUKA line where it merges with another eddy propagating from the east at 30°N. The variation at the ASUKA line is, however, less dominated by this mode; instead, it includes the SSDT variations in the south of Shikoku and the east of Kyushu which would be directly affected by eddies from the east without passing the Tokara Strait. On the other hand, the same analysis for movements of the Kuroshio axis in the Strait indicates that they are governed by short-term variations locally confined to the Kuroshio in the East China Sea without being induced by meso-scale eddies. This results, however, seem to depend strongly on a time scale of interest. It is suggested that the long-term movements of the Kuroshio axis in the Strait would demonstrate coincidence with SSDT variation in the south of Japan. 相似文献
15.
Motohiko Kashima Shiro Imawaki Shin-Ichiro Umatani Hiroshi Uchida Yuji Hashibe Hiroshi Ichikawa Masao Fukasawa 《Journal of Oceanography》2003,59(3):291-301
Theoretically, the geostrophic approximation holds for the low-frequency flow field, but no detailed examination has been
done on how well the estimated geostrophic velocity corresponds with the observed velocity. Intensive surveys were carried
out during 1993–1995 in the Kuroshio and its recirculation regions south of Shikoku, Japan, including repeated hydrographic
surveys and direct current measurements at nominal depths of 700, 1500 and 3000 m. For these depth intervals, vertical differences
of estimated geostrophic velocity are compared with those of observed velocity. For the intermediate layer (between 700 and
1500 m depths), the slope of the regression line is 0.99, correlation coefficient is 0.98, and the root-mean-square of difference
from geostrophic balance is 2.8 cm/s which is close to the estimated error of 2.1 cm/s. For the deep layer (between 1500 and
3000 m depths), the corresponding values are 0.82, 0.93, 1.2 cm/s and 2.0 cm/s, respectively. The results indicate that the
estimated geostrophic velocity compares well with the observed velocity in these regions.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
16.
Hirohiko Nakamura Ayako Nishina Kotaro Tabata Masataka Higashi Akimasa Habano Toru Yamashiro 《Journal of Oceanography》2012,68(2):321-336
A time series of surface geostrophic velocity is developed using satellite altimetry data during 1992–2010 for a track across
the Kuroshio southeast of Kyushu, Japan. The temporal mean geostrophic velocity is estimated by combining the along-track
sea level anomaly and shipboard ADCP data. This approximately 6-km resolution dataset is successful in representing the Kuroshio
cross-current structure and temporal variation of the Kuroshio current-axis position during 2000–2010. The authors use this
dataset to examine the winter Kuroshio path destabilization phenomenon. Its seasonal features are characterized as follows:
the velocity shear on the inshore side of the Kuroshio becomes stronger and the Kuroshio path state becomes unstable from
the summer to winter. This evidence is consistent with the hypothetical mechanism governing the destabilization phenomenon
discussed in a previous study. Furthermore, the interannual amplitude modulation of the seasonality is examined in relation
to interannual variations in the winter northerly wind over the northern Okinawa Trough and the Pacific Decadal Oscillation
(PDO) index. The destabilization phenomenon appears 15 times in the period 2000–2010. Ten cases are related to local wind
effects, and 7 of these are also connected with the PDO index. This is probably because the winter northerly wind over the
northern Okinawa Trough is regulated by the PDO signal in interannual time-scales. Only 4 cases are related to the PDO index,
but their driving mechanism remains uncertain. 相似文献
17.
The sea surface dynamic topography (the sea surface height relative to the geoid; hereafter abbreviated SSDT) can be divided into the temporal mean SSDT and the fluctuation SSDT around the mean. We use the optimal interpolation method to reduce the satellite radial orbit error and estimate the fluctuation SSDT southeast of Japan from Seasat altimetry data during the 17-day near-repeat mission. The fluctuation SSDT is further combined with the mean geopotential anomalies estimated from hydrographic data during the Seasat mission in order to give the approximated total SSDT, called here the composite SSDT (the approximated mean plus fluctuation SSDT's). The fluctuation SSDT is in accord with the low-frequency sea-level fluctuation recorded at tide gauge stations in the Japanese islands. The composite SSDT describes thoroughly variations of the location of the Kuroshio axis south of Japan determined on the basis of the GEK (Geomagnetic Electro-Kinematograph) surface velocities and the horizontal temperature distribution. The composite SSDT also agrees with oceanic variations east of Japan found in the temperature distribution at the depth of 200 m. These results confirm that the SSDT derived from altimetry data can provide fairly precise synoptic views of low-frequency oceanic phenomena. 相似文献
18.
Ryoko Tokeshi Kaoru Ichikawa Satoshi Fujii Kenji Sato Shoichiro Kojima 《Journal of Oceanography》2007,63(4):711-720
A method to extract geostrophic current in the daily mean HF radar data in the Kuroshio upstream region is established by
comparison with geostrophic velocity determined from the along-track altimetry data. The estimated Ekman current in the HF
velocity is 1.2% (1.5%) and 48° (38°)-clockwise rotated with respect to the daily mean wind in (outside) the Kuroshio. Furthermore,
additional temporal smoothing is found necessary to remove residual ageostrophic currents such as the inertial oscillation.
After removal of the ageostrophic components, the HF geostrophic velocity agrees well with that from the altimetry data with
rms difference 0.14 (0.12) m/s in (outside) the Kuroshio. 相似文献
19.
Yutaka Nagata Junichi Takeuchi Makoto Uchida Isamu Ishikura Yoshitaka Morikawa Takashi Koike 《Journal of Oceanography》1999,55(3):407-416
The Kuroshio flows very close to Cape Shionomisaki when it takes a straight path. The detailed observations of the Kuroshio were made both on board the R/V Seisui-maru of Mie University and on board the R/V Wakayama of the Wakayama Prefectural Fisheries Experimental Station on June 11–14, 1996. It was confirmed that the current zone of the Kuroshio touches the coast and bottom slope just off Cape Shionomiaki, and that the coastal water to the east of the cape was completely separated from that to the west. The relatively high sea level difference between Kushimoto and Uragami could be caused by this separation of the coastal waters when the Kuroshio takes a straight path. This flow is rather curious, as the geostrophic flow, which has a barotropic nature and touches the bottom, would be constrained to follow bottom contours due to the vorticity conservation law. The reason why the Kuroshio leaves the bottom slope to the east of Cape Shionomisaki is attributed to the high curvature of the bottom contours there: if the current were to follow the contours, the centrifugal term in the equation of motion would become large and comparablee to the Coriolis (or pressure gradient) term, and the geostrophic balance would be destroyed. This creates a current-shadow zone just to the east of the cape. As the reason why the current zone of the Kuroshio intrudes into the coastal region to the west of the cape, it is suggested that the Kii Bifurcation Current off the southwest coast of the Kii Peninsula, which is usually found when the Kuroshio takes the straight path, has the effect of drawing the Kuroshio water into the coastal region. The sea level difference between Kushimoto and Uragami is often used to monitor the flow pattern of the Kuroshio near the Kii Peninsula. It should be noted that Uragami is located in the current shadow zone, while Kushimoto lies in the region where the offshore Kuroshio water intrudes into the coastal region. The resulting large sea level difference indicates that the Kuroshio is flowing along the straight path. 相似文献
20.
Motohiko Kashima Shin-Ichi Ito Kaoru Ichikawa Shiro Imawaki Shin-Ichiro Umatani Hiroshi Uchida Takashi Setou 《Journal of Oceanography》2009,65(1):73-80
A quasiperiodic variation of 100–110 days in the Kuroshio path off Cape Ashizuri, resulting from the passage of small meanders,
was detected by observation with moored current meters during 1993–1995. TOPEX/POSEIDON altimeter data covering 9 years showed
that the quasiperiodic variation period was not persistent and modulated twice, with a ∼110-day period from mid-1993 to late
1996, a ∼150-day period from late 1996 to mid-1999, and a ∼110-day period from mid-1999 to late 2001. The quasiperiodic variations
of the Kuroshio path migration were contemporaneous with the quasiperiodic arrivals of mesoscale eddies from the east along
27–32°N over the same ∼110- and ∼150-day period quasiperiodic variations. The periodic arrivals of the eddies configure the
periodic variations of the Kuroshio path and its inter-annual modulation. 相似文献