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1.
INTRODUCFIONTheknowledgeoffinestructureandmicrostructureplaysamajorroleintheresearchofoceanicdiapycnalmixing.Sofarastheliteratureisconcerned,finestructuresareroughlydefinedassmallstructuresdistributedonverticalscalesfromImto100m(Munk,1981),whereasmicrostructureshavesmallerscales.Forsimplicity,thesetwofeatureswillbecalledfinestructures ThestudywassupportedbytheNationalNaturalaudienceFoundationofChinaundercontractsNo.49376257,No.4950/6071andNo.49676275,andtheResearchFundfortutorialPngr… 相似文献
2.
A marine magnetic survey was carried out in and around the northern part of Socotra Basin, offshore Korea (31°42′32″–32°46′29″N
and 123°56′26″–125°49′16″E), in order to better delineate its northern and eastern boundaries. Analyses of the observed magnetic
field and estimation of the basement depth were used to assess these boundaries. The power spectrum and the three-dimensional
analytical signal methods were used for depth estimation and to reconstruct basement configuration. Estimated depths resulting
from the power spectrum method range from 1.5 to 6.0 km for deep sources (basement troughs), and from 0.3 to 1.7 km for shallower
sources (basement peaks). An isopach map shows that the sedimentary sequence varies from 1.4 to 6.0 km in thickness. Estimated
depths from the analytic signal method fluctuate in the range 1.2–6 km. The results of the observed field analysis and depth
estimation indicate good agreement with the formerly proposed eastern boundary but disagreement with the northern boundary.
The findings suggest either an extension of the Socotra Basin or the existence of other sub-basins possibly interconnected
with the study area. 相似文献
3.
Inertial oscillations as deep ocean response to hurricanes 总被引:1,自引:0,他引:1
We discuss the deep ocean response to passing hurricanes (aka typhoons), which are considered as generators of near-inertial, internal waves. The analysis of data collected in the northwestern
parts of the Pacific and Atlantic oceans in the hurricane season permit us to assess the deep ocean response to such a strong
atmospheric forcing. A large number of moorings (more than 100) in the northwestern Pacific have allowed us to characterize
the spatial features of the oceanic response to typhoons and the variable downward velocity of near-inertial wave propagation.
The velocity of their downward propagation varies in the range 1–10 m/hour. It is higher in the regions of low stratification
and high anticyclonic vorticity. The inertial oscillations generated by a hurricane last for 10–12 days. The mean anticyclonic
vorticity in the region increases the effective frequency of inertial oscillations by 0.001–0.004 cyc/hour. 相似文献
4.
E. G. Merzlyakov Yu. I. Portnyagin T. V. Solov’eva A. I. Pogoreltsev E. V. Suvorova 《Izvestiya Atmospheric and Oceanic Physics》2012,48(2):174-184
Based on empirical monthly data on the parameters of oscillations in the horizontal wind component of the diurnal migrating
tide, we calculated the altitude-latitude distributions of the parameters of oscillations in the vertical wind component of
the diurnal tide in the region of the mesosphere and lower thermosphere (80–100 km). The initial data were obtained from satellite
observations of the mesosphere and lower thermosphere at altitudes from 90 to 120 km and from data of ground-based sounding
of this region using the radio meteor method and the method of partial reflections in the altitude range from 80 to 100 km.
We compare the resulting distributions with the results of numerical modeling for the migrating diurnal tide using a global
circulation model for the middle and upper atmosphere. It is shown that, accurate to measurement errors, there is a good agreement
between the distributions of parameters of the migrating diurnal tide obtained by the models. One specific feature of the
empirical distributions of the amplitude of the vertical wind oscillations is that there are three regions of increased amplitude
values—in the vicinity of the equator and at 30° N and 30° S latitudes—which were observed for all seasons. The maximum value
of the amplitude of the vertical wind oscillations is approximately 0.1 m/s. The divergence of the Eliassen-Palm flux was
estimated to be on the order of 10 m s−1 day−1. 相似文献
5.
Geology of the Continental Margin of Enderby and Mac. Robertson Lands, East Antarctica: Insights from a Regional Data Set 总被引:1,自引:0,他引:1
H. M. J. Stagg J. B. Colwel N. G. Direen P. E. O’Brien G. Bernardel I. Borissova B. J. Brown T. Ishirara 《Marine Geophysical Researches》2004,25(3-4):183-219
In 2001 and 2002, Australia acquired an integrated geophysical data set over the deep-water continental margin of East Antarctica
from west of Enderby Land to offshore from Prydz Bay. The data include approximately 7700 km of high-quality, deep-seismic
data with coincident gravity, magnetic and bathymetry data, and 37 non-reversed refraction stations using expendable sonobuoys.
Integration of these data with similar quality data recorded by Japan in 1999 allows a new regional interpretation of this
sector of the Antarctic margin.
This part of the Antarctic continental margin formed during the breakup of the eastern margin of India and East Antarctica,
which culminated with the onset of seafloor spreading in the Valanginian. The geology of the Antarctic margin and the adjacent
oceanic crust can be divided into distinct east and west sectors by an interpreted crustal boundary at approximately 58° E.
Across this boundary, the continent–ocean boundary (COB), defined as the inboard edge of unequivocal oceanic crust, steps
outboard from west to east by about 100 km.
Structure in the sector west of 58° E is largely controlled by the mixed rift-transform setting. The edge of the onshore Archaean–Proterozoic
Napier Complex is downfaulted oceanwards near the shelf edge by at least 6 km and these rocks are interpreted to underlie
a rift basin beneath the continental slope. The thickness of rift and pre-rift rocks cannot be accurately determined with
the available data, but they appear to be relatively thin. The margin is overlain by a blanket of post-rift sedimentary rocks
that are up to 6 km thick beneath the lower continental slope.
The COB in this sector is interpreted from the seismic reflection data and potential field modelling to coincide with the
base of a basement depression at 8.0–8.5 s two-way time, approximately 170 km oceanwards of the shelf-edge bounding fault
system. Oceanic crust in this sector is highly variable in character, from rugged with a relief of more than 1 km over distances
of 10–20 km, to rugose with low-amplitude relief set on a long-wavelength undulating basement. The crustal velocity profile
appears unusual, with velocities of 7.6–7.95 km s−1 being recorded at several stations at a depth that gives a thickness of crust of only 4 km. If these velocities are from
mantle, then the thin crust may be due to the presence of fracture zones. Alternatively, the velocities may be coming from
a lower crust that has been heavily altered by the intrusion of mantle rocks.
The sector east of 58° E has formed in a normal rifted margin setting, with complexities in the east from the underlying structure
of the N–S trending Palaeozoic Lambert Graben. The Napier Complex is downfaulted to depths of 8–10 km beneath the upper continental
slope, and the margin rift basin is more than 300 km wide. As in the western sector, the rift-stage rocks are probably relatively
thin. This part of the margin is blanketed by post-rift sediments that are up to about 8 km thick.
The interpreted COB in the eastern sector is the most prominent boundary in deep water, and typically coincides with a prominent
oceanwards step-up in the basement level of up to 1 km. As in the west, the interpretation of this boundary is supported by
potential field modelling. The oceanic crust adjacent to the COB in this sector has a highly distinctive character, commonly
with (1) a smooth upper surface underlain by short, seaward-dipping flows; (2) a transparent upper crustal layer; (3) a lower
crust dominated by dipping high-amplitude reflections that probably reflect intruded or altered shears; (4) a strong reflection
Moho, confirmed by seismic refraction modelling; and (5) prominent landward-dipping upper mantle reflections on several adjacent
lines. A similar style of oceanic crust is also found in contemporaneous ocean basins that developed between Greater India
and Australia–Antarctica west of Bruce Rise on the Antarctic margin, and along the Cuvier margin of northwest Australia. 相似文献
6.
Previous studies have determined many types of pores in shale, such as organic pores, inorganic pores and microfractures. In this study, pores are classified as intergranular, intraparticle, and organic pores based on the location of their occurrence. The heterogeneities of the three pore types and their effects on the occurrence of shale gas, which is of utmost practical importance for shale gas exploration and development, are discussed. In this study, the three types of pores are quantitatively characterized using fractal and multifractal methods. The mean fractal dimension and mean width of the multifractal spectrum of these pores are found to be different, i.e., 1.5985 and 1.665 for intraparticle pores, 1.5869 and 1.475 for intergranular pores, and 1.6 and 1.3725 for organic pores. Intraparticle pores have the highest heterogeneity, intergranular pores have intermediate heterogeneity, and organic pores have the lowest heterogeneity. SEM images show that organic pores have good connectivity, homogeneous distribution, and small range of aperture change but have the lowest heterogeneity even where pores are abundant; thus, they provide the largest shale gas occurrence space. In contrast, intergranular pores are less abundant, have lower connectivity, and have higher heterogeneity than organic pores, thereby providing a relatively smaller shale gas occurrence space. Finally, intraparticle pores are the least abundant and possess the poorest connectivity, largest range of aperture change, and highest heterogeneity of the three pore types, thereby providing the smallest shale gas occurrence space. We conclude that organic pores are crucial to the occurrence of shale gas and can provide a new index for the evaluation of shale gas exploration and development. 相似文献
7.
不同形态的多重分形频谱可用于含油气远景评价和油气分布规律的研究,本文运用多重分形矩方法对中央峡谷体系已钻井获得的2 684个数据13项油气指标的多重分形谱函数形态特征进行了研究。结果表明,琼东南盆地深水区中具有较强多重分形特征的指标,具有多重分形谱函数宽而连续的特征,成一右偏弧形状;而其他指标则显示较弱或单一分形特征。将这一结果与常用的统计方法因子分析结果做对比,结果表明,通过多重分形分析对这几项油气指标的分组结果与常规的统计分析结果基本吻合。为更进一步探究这几种主要油气指标在油气指示中的权重,采用主成分分析法对这几种指标进行分析,结果表明在琼东南盆地深水区,异丁烷、正丁烷、异戊烷为圈定油气远景区的重要指标。 相似文献
8.
黑潮延伸体邻近区域中尺度涡特征统计分析 总被引:7,自引:3,他引:4
本文利用20年的卫星高度计资料,对黑潮延伸体邻近海区(25°—45°N,135°E—175°W)中尺度涡的统计特征以及季节变化进行了统计研究。基于涡旋自动识别方法,共识别出本区域3006个气旋涡轨迹和2887个反气旋涡轨迹,其平均周期分别为9.99周和11.00周,平均半径分别为69.5km和71.8km。长生命周期涡旋的平均半径、涡度、涡动能(EKE)和涡旋能量密度(EI)在生命周期内大致都经历了增大-基本保持不变-减小这三个阶段。绝大多数涡旋沿纬线向西移动,经向移动距离较小,气旋涡和反气旋涡在西向传播过程中都具有明显的向南(赤道)偏离趋势。涡旋的生成数量与总数量均在春夏季达到最多,且这一时期涡旋的平均涡度、EKE、EI处于较高水平。 相似文献
9.
A. Elverhøi H. Norem E. S. Andersen J. A. Dowdeswell I. Fossen H. Haflidason N. H. Kenyon J. S. Laberg E. L. King H. P. Sejrup A. Solheim T. Vorren 《Geo-Marine Letters》1997,17(2):119-125
Debris lobes with characteristic lengths, widths, and thickness of 30–200 km, 2–10 km, and 10–50 m, respectively, represent
the main building blocks of deep-sea fans along the Norwegian–Barents Sea continental margin. Their formation is closely related
to the input of clay-rich sediments to the upper continental slope by glaciers during periods of maximum ice advance. It is
likely that slide release was a consequence of an instability arising from high sedimentation rates on the upper continental
slope. The flow behavior of the debris lobes can be described by a Bingham flow model.
Received: 17 November 1995 / Revision received: 24 June 1996 相似文献
10.
Based on the surface drifters that moved out from the Sea of Okhotsk to the Pacific, the surface velocity fields of mean,
eddy, and tidal components in the Oyashio region are examined for the period September 1999 to August 2000. Along the southern
Kuril Island Chain, the Oyashio Current, having a width of ∼100 km, exists with velocities of 0.2–0.4 m s−1. From 40°N to 43°N, the Subarctic Current flows east- or northeastward with velocities of 0.1–0.3 m s−1, accompanied by a meandering Oyashio or Subarctic front. Between the Oyashio and Subarctic current regions, an eddy-dominant
region exists with both cyclonic and anticyclonic eddies. The existence of an eastward flow just south of Bussol' Strait is
suggested. The 2000 anticyclonic warmcore ring located south of Hokkaido was found to have a nearly symmetric velocity structure
with a maximum velocity of ∼0.7 m s−1 at 70 km from the eddy center. Diurnal tidal currents with a clockwise tidal ellipse are amplified over the shelf and slope
off Urup and Iturup Islands, suggesting the presence of diurnal shelf waves. From Lagrangian statistics, the single-particle
diffusivity is estimated to be ∼10 × 107 cm2s−1. 相似文献
11.
The Baker River is the largest free-flowing river in Chilean Patagonia. Long-range dependence (LRD), a recognised hydrological property of river runoff worldwide, was detected for the Baker River runoff time series. Analyses were conducted on a monthly scale between 1961 and 2015 using the fractal and multifractal detrended fluctuation analysis methodology. A long-range-dependent Hurst coefficient (H) equal to 0.94 was obtained. A scaling range, which is the signature of LRD, was detected for the Baker River runoff time series between 1 and 5.25 years. Baker River runoff showed a strong correlation (r?=?0.96) with the Antarctic Oscillation (AAO) Index during the 2007–2015 period. The high storage capacity of Lake General Carrera, the size of the Baker River basin area and the dynamics of AAO are proposed as main factors that contribute to the emergence of LRD in the Baker River runoff time series. 相似文献
12.
S. F. Dotsenko 《Physical Oceanography》2005,15(3):133-141
Within the framework of a nonlinear model of long waves, we present the estimates of the parameters of tsunami waves along
the south coast of the Crimean Peninsula (from Cape Khersones to Cape Meganom) with a space resolution of 2.5 km. The numerical
analysis is carried out for four typical positions of the elliptic zones of generation and the range of magnitudes 6.5–7.5.
We study the space structure of waves and determine the amplitudes and periods of oscillations of the level at 11 points of
the analyzed part of the coastline of the Black Sea.
__________
Translated from Morskoi Gidrofizicheskii Zhurnal, No. 3, pp. 3 – 10, May–June, 2005. 相似文献
13.
Laura S. L. Kong Robert S. Detrick Paul J. Fox Larry A. Mayer W. B. F. Ryan 《Marine Geophysical Researches》1988,10(1-2):59-90
High-resolution Sea Beam bathymetry and Sea MARC I side scan sonar data have been obtained in the MARK area, a 100-km-long
portion of the Mid-Atlantic Ridge rift valley south of the Kane Fracture Zone. These data reveal a surprisingly complex rift
valley structure that is composed of two distinct spreading cells which overlap to create a small, zero-offset transform or
discordant zone. The northern spreading cell consists of a magmatically robust, active ridge segment 40–50 km in length that
extends from the eastern Kane ridge-transform intersection south to about 23°12′ N. The rift valley in this area is dominated
by a large constructional volcanic ridge that creates 200–500 m of relief and is associated with high-temperature hydrothermal
activity. The southern spreading cell is characterized by a NNE-trending band of small (50–200 m high), conical volcanos that
are built upon relatively old, fissured and sediment-covered lavas, and which in some cases are themselves fissured and faulted.
This cell appears to be in a predominantly extensional phase with only small, isolated eruptions. These two spreading cells
overlap in an anomalous zone between 23°05′ N and 23°17′ N that lacks a well-developed rift valley or neovolcanic zone, and
may represent a slow-spreading ridge analogue to the overlapping spreading centers found at the East Pacific Rise. Despite
the complexity of the MARK area, volcanic and tectonic activity appears to be confined to the 10–17 km wide rift valley floor.
Block faulting along near-vertical, small-offset normal faults, accompanied by minor amounts of back-tilting (generally less
than 5°), begins within a few km of the ridge axis and is largely completed by the time the crust is transported up into the
rift valley walls. Features that appear to be constructional volcanic ridges formed in the median valley are preserved largely
intact in the rift mountains. Mass-wasting and gullying of scarp faces, and sedimentation which buries low-relief seafloor
features, are the major geological processes occurring outside of the rift valley. The morphological and structural heterogeneity
within the MARK rift valley and in the flanking rift mountains documented in this study are largely the product of two spreading
cells that evolve independently to the interplay between extensional tectonism and episodic variations in magma production
rates. 相似文献
14.
Bathymetry, satellite-derived gravity, and interpreted seismic reflection data across the northern Falkland/Malvinas Plateau
fossil continent–ocean transform rim may record the degree of mechanical coupling across the boundary after ridge–transform
intersection time. The rim comprises a broad microcontinental block in the east and a continental marginal fracture ridge
50–100 km wide elsewhere. Free-air gravity anomalies tentatively suggest that the fracture ridge is locked against oceanic
elastic lithosphere both to the north (Argentine Basin) and south (Central Falkland Basin).
Received: 18 January 1996 / Revision received: 25 March 1995 相似文献
15.
The origins and evolutions of two anticyclonic eddies in the northeastern South China Sea (SCS) were examined using multi-satellite
remote sensing data, trajectory data of surface drifting buoys, and in-situ hydrographic data during winter 2003/2004. The results showed that buoy 22918 tracked an anti-cyclonic warm-core eddy (AE1)
for about 20 days (December 4–23, 2003) in the northeastern SCS, and then escaped from AE1 eventually. Subsequently to that,
buoy 22517 remained within a different anti-cyclonic warm-core eddy (AE2) for about 78 days (from January 28 to April 14,
2004) in the same area. It drifted southwestward for about 540 km, and finally entered into the so-called “Luzon Gyre”. Using
inference from sea level anomaly (SLA), sea surface temperature (SST), geostrophic currents and the buoys’ trajectories, it
is shown that both eddies propagated southwestward along the continental slope of the northern SCS. The mean speeds of AE1
and AE2 movements were 9.7 cm/s and 10.5 cm/s, respectively, which are similar to the phase speed of Rossby waves in the northern
SCS. The variation of instantaneous speeds of the eddy movement and intensity of anticyclonic eddy may suggest complex interactions
between an anticyclonic eddy and its ambient fluids in the northern SCS, where the eddy propagated southwestward with Rossby
waves. Furthermore, SLA and SST images in combination with the temperature and salinity profiles obtained during a cruise
suggested that AE1 was generated in the interior SCS and AE2 was shed from the “Kuroshio meander”. 相似文献
16.
Sumanta Dandapath Bishwajit Chakraborty Nicolas Maslov Siddaiah M. Karisiddaiah Dhrupad Ghosh William Fernandes Andrew Menezes 《Marine and Petroleum Geology》2012,29(1):115-128
Here we apply quantitative technique to describe the seafloor seepages based on the multi-beam backscatter and bathymetric investigations to characterize the pockmark morphology. The variable seafloor backscatter strength for coarser seafloor sediments are related to the diagenesis derived from biodegraded seepages. In this regard, box counting method is used to estimate ‘fractal dimension’ for backscatter imagery data of 398 blocks. These blocks are further sub-grouped into six classes depending on the spread of pockmark related seepages. The study area lies 102 km west off Marmagao along the central west coast of India which contains pre-dominantly (70%) gas-charged sediments. Comparison between the estimated self-similar fractals reveals that there is approximately 97% correlation between the box (Dbox) and information (Dinfo) dimensions. Box dimension–derived fractal dimension values, suggest that the seepages are more along the fault trace in deeper waters, in comparison to sparsely distributed shallow water seepages. Besides, this poor seepage is confined within the smooth to moderately rough seafloor. It is established that the high backscatter strength along the upper slope of the pockmark region having higher fractal dimensions reflects multifractal behavior of seepage distribution. Entire area indicates patchy seepage patterns as supported by estimated fractal values showing intermittent fluctuations, which emphasizes non-linear behavior. Estimated self organizing criticality (SOC) parameters for six representative blocks reveal that the nature of pockmark, fault trace, sediment nature coupled with slumping of pockmark’s wall, sediment movement due to bottom currents are controlling the dynamic balance in the area seepage system. Further, our study emphasizing the multifractal behavior of seepage blocks, clearly depicts the drift in the seepage pattern. 相似文献
17.
To detect eddies, intensive surveys of the northeast South China Sea (SCS) (114°30′–121°30′ E, 17°–22°N) were conducted in
July 1998 during the international SCS Monsoon Experiment (SCSMEX), the U.S. Navy using Airborne Expendable Bathythermograph
and Conductivity-Temperature-Depth sensors (AXBT/AXCTD), and the Chinese Academy of Sciences using Acoustic Doppler Current
Profilers (ADCP). The hydrographic survey included 307 AXBT and 9 AXCTD stations, distributed uniformly throughout the survey
area. The ADCP survey had two sections. The velocity field inverted from the AXBT/AXCTD data and analyzed from the ADCP data
confirm the existence of a low salinity, cool-core cyclonic eddy located northwest of Luzon Island (i.e., the Northwest Luzon
Eddy). The radius of this eddy is approximately 150 km. The horizontal temperature gradient of the eddy increases with depth
from the surface to 100 m and then decreases with depth below 100 m. The cool core was evident from the surface to 300 m depth,
being 1°–2°C cooler inside the eddy than outside. The tangential velocity of the eddy is around 30–40 cm/s above 50 m and
decreases with depth. At 300 m depth, it becomes less than 5 cm/s.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
18.
西北太平洋柔鱼渔场分布与涡动能变化的相关关系 总被引:1,自引:0,他引:1
本研究利用卫星高度计数据计算海洋涡动能(Eddy Kinetic Energy,EKE),根据2010–2016年中国远洋渔业协会鱿钓组提供的西北太平洋柔鱼(Ommastrephes bartramii)渔业生产数据,分析柔鱼渔场的EKE分布特征以及黑潮延伸体EKE的时空变化对柔鱼渔场分布的影响。结果显示,柔鱼渔场的EKE与单位捕捞努力量渔获量(Catch Per Unit Effort,CPUE)呈显著负相关(P <0.01),EKE对CPUE的有效影响范围为0~1 500 cm^2/s^2,最适宜EKE范围为25~150 cm^2/s^2。黑潮延伸体EKE强度由西向东递减,与CPUE年平均呈负相关,相关系数为0.81(P <0.05)。按黑潮延伸体经度范围分为4个子区域,CPUE月平均纬度重心响应该月EKE强度最高的子区域。盛渔期8–10月渔场距离黑潮延伸体在800~1 000 km范围内时,CPUE随距离增加而增大,其中最适宜的距离范围为850~950 km。研究表明,当黑潮延伸体路径弯曲多变时,EKE增大,而柔鱼CPUE变低,渔场位置越偏北。 相似文献
19.
Shuiming Chen 《Journal of Oceanography》2008,64(6):891-897
The position and strength of the surface Kuroshio Extension Front (KEF), defined as the sea surface temperature (SST) gradient
maximum adjacent to the Kuroshio Extension (KE) axis (approximated by a specific SSH contour consistently located at, or near,
the maximum of the SSH gradient magnitude), have been studied using weekly, microwave SST measurements from the later 1997
to early 2008. The mean KEF meanders twice around ∼36°N between the east coast of Japan and 153°E. It then migrates southeast
to ∼34°N, just before reaching the Shatsky Rise (∼158°E), then progresses mostly eastward. Spatially, the KEF is strongest
near the Japan coast, while it is seasonally strongest in winter and weakest in summer. Low-frequency variations of its strength,
most notably in its upstream region, can be related to the known bimodal states of the KE. During 2003–2005, when the KE was
in its stable state, the winter KEF SST gradient exceeded 10°C/100 km. 相似文献
20.
Regional gravity and magnetic studies over the continental margin of the central west coast of India
L. V. Subba Raju K. A. Kamesh Raju V. Subrahmanyam D. Gopala Rao 《Geo-Marine Letters》1990,10(1):31-36
Gravity studies over the continental margin of the central west coast of India show a sediment thickness of 2–3 km on the
shelf associated with deeper horst and graben structures, of 6 km in the shelf margin basin, and about 1 km in the deep sea.
The upward trend in free-air gravity anomaly toward the deep sea region is interpreted as crustal thinning. Model studies
indicate a 25-km-thick crust in the shelf region and a minimum of 18 km in the more offshore region. An abrupt magnetic signature
change suggests differential basement depths in the shelf region. Major faulting in the region is confirmed in water depths
of approximately 100–200 m. 相似文献