共查询到20条相似文献，搜索用时 27 毫秒
1.
Ju. V. Artamonov A. V. Fedirko E. A. Skripaleva 《Izvestiya Atmospheric and Oceanic Physics》2016,52(9):1051-1063
Based on the satellite altimetry dataset of sea level anomalies, the climatic hydrological database World Ocean Atlas-2009, ocean reanalysis ECMWF ORA-S3, and wind velocity components from NCEP/NCAR reanalysis, the interannual variability of Antarctic Circumpolar Current (ACC) transport in the ocean upper layer is investigated for the period 1959–2008, and estimations of correlative connections between ACC transport and wind velocity components are performed. It has been revealed that the maximum (by absolute value) linear trends of ACC transport over the last 50 years are observed in the date-line region, in the Western and Eastern Atlantic and the western part of the Indian Ocean. The greatest increase in wind velocity for this period for the zonal component is observed in Drake Passage, at Greenwich meridian, in the Indian Ocean near 90° E, and in the date-line region; for the meridional component, it is in the Western and Eastern Pacific, in Drake Passage, and to the south of Africa. It has been shown that the basic energy-carrying frequencies of interannual variability of ACC transport and wind velocity components, as well as their correlative connections, correspond to the periods of basic large-scale modes of atmospheric circulation: multidecadal and interdecadal oscillations, Antarctic Circumpolar Wave, Southern Annual Mode, and Southern Oscillation. A significant influence of the wind field on the interannual variability of ACC transport is observed in the Western Pacific (140° E–160° W) and Eastern Pacific; Drake Passage and Western Atlantic (90°–30° W); in the Eastern Atlantic and Western Indian Ocean (10°–70° E). It has been shown in the Pacific Ocean that the ACC transport responds to changes of the meridional wind more promptly than to changes of the zonal wind. 相似文献
2.
The currents in the Drake Passage are studied from the ADCP and CTD data acquired in a section across the Drake Passage in October-November of 2011 and from the satellite altimeter data. A complicated pattern of currents including eight jets of the Antarctic Circumpolar Current (ACC) and a system of slope and abyssal currents was found. The most interesting result is the discovery of several cyclonic and anticyclonic mesoscale eddies confined to the abyss. Some reasons explaining the generation of such eddies by the meandering of the ACC jets in the upper ocean layer are presented. 相似文献
3.
《Deep Sea Research Part I: Oceanographic Research Papers》2007,54(11):1972-1984
The Southern Ocean hosts significant topographic mixing that might be associated with internal tides. Tidal signals are evident in bottom temperature at 1000 m in Drake Passage, suggesting that internal tides with an amplitude of between ∼20 and 200 m may be present. Various necessary conditions for internal tide generation show that the steep topography in and around Drake Passage can initiate internal tides, and recent global tide models have suggested this region to generate very large interface displacements. Here, we present an attempt to detect internal tides in Drake Passage. During the last 10 years, combinations of bottom pressure recorders and inverted echo sounders have been deployed in the region. The bottom pressure recorders measure predominantly the barotropic tide; the inverted echo sounders measure travel time from sea bed to sea surface and therefore are influenced both by sea level (barotropic tide) and internal sound speed (internal tide). By subtracting one from the other, the internal tide should be detectable. Although the technique works successfully around Hawaii, it does not prove the existence of large internal tides in Drake Passage. The detectability of the internal tidal signal in Drake Passage is investigated using a six-layer one-dimensional model to simulate the bottom pressure and travel time signals of a semi-diurnal tide. The temperature and salinity stratification in Drake Passage is sufficiently weak that large vertical excursions are necessary to produce a signal in travel time detectable above the noise in Drake Passage. An internal tide of at least 70 or 20 m in northern and southern Drake Passage, respectively, would be detected. The fact that these are, perhaps surprisingly, not detected by the combination of bottom pressure and travel time, constrains the internal tides in Drake Passage to be ∼20 m in southern Drake Passage, and between 20 and 70 m in northern Drake Passage. The model also predicts that satellite altimetry would not be able to detect internal tides in Drake Passage, but would in the Brazil Basin and Hawaii regions. 相似文献
4.
Over the Southern Ocean the dominant modes of the atmospheric field are known as the Southern Annular Mode (SAM) or Antarctic
Oscillation, and the Pacific South American (PSA) pattern. Statistical analysis of sea surface wind (SSW) from satellite observation
revealed two leading modes of SAM-like and PSA patterns. In the high latitudes, the SAM-like pattern of the SSW had a large
amplitude over the Bellingshausen Basin and Australian-Antarctic Basin, with opposite phase between the two basins. On the
intraseasonal time scale, large-scale sea surface height (SSH) also had notable variability, showing a basin-scale anti-phase
mode over the two basins. To explain the response of oceanic variations to these atmospheric modes, we analyzed the relationship
between the dominant modes of wind stress and large-scale SSH on the intraseasonal time scale. The SAM-like pattern of wind
stress was correlated with the SSH variation over the two basins. The SSH basin mode was most simply explained by a simple
barotropic response to the SAM-like mode of wind stress, with the curl of opposite phase between the two basins. We conclude
that the zonal asymmetry of the wind field of the SAM plays an important role in driving the antiphase SSH basin modes. 相似文献
5.
6.
Koshlyakov M. N. Repina I. A. Savchenko D. S. Tarakanov R. Y. Taroyan V. K. 《Oceanology》2019,59(2):171-181
Oceanology - Satellite altimeter observation data collected over 22 years are used to analyze the structure and variability of mesoscale fluctuations of ocean currents in the Drake Passage and... 相似文献
7.
An ocean general circulation model (OGCM) is used to identify a Southern Ocean southeast Pacific intrinsic mode of low frequency variability. Using CORE data a comprehensive suite of experiments were carried out to elucidate excitation and amplification responses of this intrinsic mode to low frequency forcing (ENSO, SAM) and stochastic forcing due to high frequency winds. Subsurface anomalies were found to teleconnect the Pacific and Atlantic regions of the Antarctic Circumpolar Current (ACC) thermocline. The Pacific region of the ACC is characterised by intrinsic baroclinic disturbances that respond to both SAM and ENSO, while the Atlantic sector of the ACC is sensitive to higher frequency winds that act to amplify thermocline anomalies propagating downstream from the Pacific. Non-stationary cluster analysis was used to identify the system’s dynamical regimes and characterise meta-stability, persistence and transitions between the respective states. This analysis reveals significant trends, indicating fundamental changes to the meta-stability of the ocean dynamics in response to changes in atmospheric forcing. Intrinsic variability in sea-ice concentration was found to be coupled to thermocline processes. Sea-ice variability localised in the Atlantic was most closely associated with high frequency weather forcing. The SAM was associated with a circumpolar sea-ice response whereas ENSO was found to be a major driver of sea-ice variability only in the Pacific. This simulation study identifies plausible mechanisms that determine the predictability of the Southern Ocean climate on multi-decadal timescales. 相似文献
8.
Methods from chaos theory are applied to the analysis of the circulation in the Southern Ocean, using velocity fields produced by a realistic global ocean model. We plot the intersections of individual trajectories encircling Antarctica with a vertical plane in the Drake passage. This so-called Poincaré section shows a drastic difference between regular trajectories in a core region of the Antarctic Circumpolar Current (ACC), and chaotic, mixing trajectories in the surrounding region. It also shows that there is a region with overturning circulation of approximately 3.5 Sv in the ACC, with downwelling on the northern side and upwelling on the southern side, which may be related to the Deacon cell. 相似文献
9.
Xiaoqin Xiong Xuhua Cheng Niansen Ou Tao Feng Jianhuang Qin Xiao Chen Rui Xin Huang 《海洋学报(英文版)》2022,41(5):78-89
Seasonal and interannual variability of ocean bottom pressure(OBP) in the Southern Ocean was investigated using Gravity Recovery and Climate Experiment(GRACE) data and a Pressure Coordinate Ocean Model(PCOM)based on mass conservation. By comparing OBP, steric sea level, and sea level, it is found that at high latitudes the OBP variability dominates the sea level variability at seasonal-to-decadal time scales. The diagnostic OBP based on barotropic vorticity equation has a good correlation with t... 相似文献
10.
南大洋Ekman输运是全球大气-海洋耦合气候系统的重要组成部分,对该区域Ekman动力过程的研究极为重要。首先基于实测数据和文献资料,对GEKCO2(Geostrophicand EkmanCurrent Observatory2)产品提供的Ekman流数据进行了评估,验证了数据的有效性;并结合CCMP(cross-calibratedmulti-platform)、ERA5(thefifthgenerationEuropeancentreformedium-range weatherforecastsatmosphericreanalysis)风场数据,采用经验正交函数分析法(empiricalorthogonal function,EOF)等方法分析了2010—2018年南大洋Ekman流的时空变化规律。结果表明:(1)南大洋Ekman流速集中在9—11 cm/s,且具有很强的月际变化特征(7月最强, 12月最弱);(2)南大洋40°S以北海域是Ekman流速随时间变化较大的区域;(3)南大洋Ekman流速的EOF分析显示:第一模态和风场存在较强的相关性,表现为流速在整体上同时增强或减弱;第二模态和南半球中高纬大气环流存在较强的相关性,表现为以50°S为界南北流速反向变化;(4)Ekman流左偏角度集中在60°—75°,其中概率密度最大值处所对应的角度为67.5°。通过矢量相关分析,得到30°—35°S海域的平均偏角存在月际变化。南大洋的Ekman动力过程对海洋环流和全球气候系统具有重大影响,本文对于进一步理解南大洋的Ekman过程具有一定的参考价值。 相似文献
11.
Ocean Model Simulation of Southern Indian Ocean Surface Currents 总被引：1，自引：0，他引：1
The dynamic importance of the Southern Indian Ocean (SIO) lies in the fact that it connects the three major world oceans: the Pacific, Atlantic, and Indian Oceans. Modeling study has been used to understand the circulation pattern of this very important region. Simulation of SIO (10°N-60°S and 30°E-120°E) is performed with z-coordinate Ocean General Circulation Model (OGCM) viz; MOM3.0 and the results have been compared with observed ship drift data. It is found that except near coastal boundaries and in equatorial region, the simulated current reproduce most well known current pattern such as Antarctic Circumpolar Current (ACC), South Equatorial Current (SEC) etc. and bears a resemblance to that of the observed data; however the magnitude of the surface current is weaker in model than the observed data, which may be due to deficiency in the forcing field and boundary condition and problem with observed data. The annual mean wind stress curl computed over the oceanic domain reveals about ACC and its similar importance. The way in which the ocean responds to the windstress and vertically integrated transport using model output is fascinating and rather good. 相似文献
12.
The dynamic importance of the Southern Indian Ocean (SIO) lies in the fact that it connects the three major world oceans: the Pacific, Atlantic, and Indian Oceans. Modeling study has been used to understand the circulation pattern of this very important region. Simulation of SIO (10°N–60°S and 30°E–120°E) is performed with z-coordinate Ocean General Circulation Model (OGCM) viz; MOM3.0 and the results have been compared with observed ship drift data. It is found that except near coastal boundaries and in equatorial region, the simulated current reproduce most well known current pattern such as Antarctic Circumpolar Current (ACC), South Equatorial Current (SEC) etc. and bears a resemblance to that of the observed data; however the magnitude of the surface current is weaker in model than the observed data, which may be due to deficiency in the forcing field and boundary condition and problem with observed data. The annual mean wind stress curl computed over the oceanic domain reveals about ACC and its similar importance. The way in which the ocean responds to the windstress and vertically integrated transport using model output is fascinating and rather good. 相似文献
13.
南大洋太平洋扇区中尺度涡旋的统计特性及其变化 总被引：1，自引：0，他引：1
中尺度涡旋在南大洋海洋动力学中具有重要地位,其对气候变化的响应表现也引起了海洋学家与气候学家的广泛关注。本文利用涡动动能与涡旋自动探测技术两种方法对南大洋太平洋扇区的涡旋特性及其变化进行了分析。与前人结果相一致的是,高值的涡动动能主要集中在南极极锋海区,并且自西向东逐渐减弱。在过去的20年里,涡动动能在太平洋扇区的显著增强也集中在中西部海域,这里也是南极绕极流斜压性较强的海域。涡旋统计特性揭示了涡动动能的空间分布及其年际变化主要归因于涡旋振幅与旋转速度,而并非涡旋个数或者涡旋半径。这些结果进一步确认了对应于南半球环状模正位相的绕极西风异常改变了南大洋的涡旋特性,从而表现出涡旋活跃性增强。 相似文献
14.
Temperature data collected over the last 36 years (1969–2004) in Drake Passage are used to examine interannual temperature variation and long-term trends in the upper ocean. To reduce the effect of variation from different sampling locations and temporal variability introduced by meridional shifts in the Polar Front (PF), the data were divided into two sub-regions north (3800 temperature profiles) and south (3400) of the PF. Temperature anomalies were formed by removing a temporal mean field for each profile in each sub-region at 100 m depth intervals from the surface to 700 m. North of the PF, statistically significant warming trends of 0.02 °C yr−1 were observed that were largely depth-independent between 100 and 700 m. A statistically significant cooling trend of −0.07 °C yr−1 was observed at the surface south of the PF, which was smaller (−0.04 °C yr−1) but still statistically significant when possible seasonal sampling biases were accounted for. The observed cooling at the surface and warming at depth is largely consistent with a poleward shift of the PF due to enhancement of westerly winds in the Southern Ocean, as recently suggested by models and observations. The observed annual temperature anomalies in the upper 400 m north of the PF and in the upper 100 m south of the PF are highly correlated to variability in sea ice, and also to climate indices of the Antarctic Oscillation and the El Niño Southern Oscillation. Variability in sea ice and temperature anomalies lag El Niño variability in the Pacific, with a phasing consistent with the observed cyclical patterns of sea ice and sea surface temperature associated with the Antarctic Circumpolar Wave or Antarctic Dipole Mode in the Southern Ocean. In contrast, the sea ice variability and temperature anomalies at all depths north of the PF and at 0–100 m depth south of the PF were primarily coincident with, or led the Antarctic Oscillation Index. No significant correlations were found with the large-scale climate variability indices in southern Drake Passage below 100 m depth, which is occupied by upper Circumpolar Deep Water (uCDW). This water mass is not formed locally, is largely isolated from the surface, and exhibits vertical and lateral homogeneity. Hence changes may be difficult to detect in the available measurements, and climate variation in the source water regions of uCDW may take a long time to reach Drake Passage. 相似文献
15.
R. Yu. Tarakanov 《Oceanology》2012,52(2):157-170
It is shown on the basis of the data of the Russian Academy of Sciences expeditions in 2003–2010, the historical CTD database,
the WOCE climatology, and the satellite altimetry that the area of the Scotia Sea and the Drake Passage is even a greater
significant orographic barrier for the eastward Antarctic Circumpolar Current (ACC) than was previously thought. It is the
current concept that this barrier is the most important for the ACC; it consists of three obstacles: the Hero Ridge with the
Phoenix Rift, the Shackleton Ridge, and the North Scotia Ridge with the relatively shallow eastern part of the Scotia Sea.
Despite the fact that all three obstacles are permeable for the layer of the Circumpolar Bottom Water (CBW; 28.16 < γ
n
< 28.26) being considered the lower part of the circumpolar water, the circulation in this layer throughout the Scotia Sea
and the Drake Passage quite substantially differs from the transfer by the surface-intensified ACC jets. Herewith, the upper
CBW boundary is the lower limit of the circumpolar coverage of the ACC jets. This result is confirmed by the near zero estimate
of the total CBW transport according to the three series of the LADCP measurements on the sections across the Drake Passage.
It is shown that the transformation (cooling and freshening) of the CBW layer, which occurs owing to the flow of the ACC over
the Shackleton Ridge, is associated with the shape and location of the ridge in the Drake Passage. The high southern part
of this ridge is a partially permeable screen for the eastward CBW transport behind which the colder and fresher waters of
the Weddell Sea and the Bransfield Strait of the same density range as the CBW penetrate into the ACC zone. The partial permeability
of the Shackleton Ridge for the CBW layer leads to the salinization of this layer on the eastern side of the ridge and to
the CBW’s freshening on the western side of this ridge, which is observed across the entire Drake Passage. 相似文献
16.
The Western Drake Passage current system is investigated using the CTD, LADCP, and SADCP data of the cross Drake section carried
out in January 2010. A complicated current structure consisting of the six Antarctic Circumpolar Current (ACC) jets as well
as the system of slope and abyssal currents was revealed. The most interesting result is the identification of the abyssal
quasi-geostrophic spurts in the northern part that probably are generated by abyssal eddy fragments, which are an imperative
part of the meandering ACC. 相似文献
17.
ＡｎａｎａｌｙｔｉｃａｌｄｉａｇｎｏｓｔｉｃｍｏｄｅｌｏｆｔｈｅＡｎｔａｒｃｔｉｃＣｉｒｃｕｍｐｏｌａｒＣｕｒｒｅｎｔ￥ＱｉａｏＦａｎｇｌｉ；ＺｈａｎｇＱｉｎｇｈｕａａｎｄＨｅＷｅｎ（ＲｅｃｅｉｖｅｄＮｏｖｅｍｂｅｒ１０，１９９５；ａｃｃｅｐｔｅｄＮ... 相似文献
18.
A coupled ice-ocean isopycnal numerical model of the Southern Ocean is established tostudy the circulation and its seasonal variability in the region around the Kerguelen Plateau. An analysis of the simulated results shows significant stripe-like structure and non-zonal feature of the Antarctic Cir-cumpolar Current (ACC) in this region. ACC begins to bifurcate and to turn its direction before meeting the plateau. The southernmost branch of ACC is near to the Antarctic coast and displays its strong interaction with the westward Antarctic Slope Current. The northern branch of ACC has a tendency of annual variations while the southern one varies in a semiannual cycle. The variation phases of both branches are coincident with that of the wind stress in this region. 相似文献
19.