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1.
For the Black-Sea region, we perform the dynamic reanalysis of the data on atmospheric circulation for the period 1958–2001
by using the HadRM3P model with a space resolution of 25 km. We estimate the mean climatic atmospheric fields of vorticity and divergence of the
wind velocity and study their space structure and seasonal variability. The climatic estimates of the annual course of vorticity
of the wind velocity over the sea are presented. The obtained large annual average values of vorticity of the velocity reveal
the predominant role played by the wind action in the generation not only of the seasonal variability but also of the mean
cyclonic circulation of waters in the Black Sea. 相似文献
2.
The seasonal climatic circulation of the sea reconstructed on the basis of assimilation of new arrays of many-year average
hydrological data in a model is analyzed. Five layers are discovered in the structure of climatic currents in the sea in depth:
the surface Ekman layer (∼ 10 m), a layer with small vertical gradients of the kinetic energy (∼ 10–60 m), a layer with relatively
high vertical gradients of the kinetic energy (∼ 60–150 m), a layer with gradual decrease in the kinetic energy and intensification
(from 250–350 m) of the east cyclonic gyre and Batumi anticyclonic eddy (∼ 150–1000 m), and an abyssal layer characterized
by an almost barotropic velocity (∼ 1000–2000 m). The specific features of the seasonal evolution of currents at these depths
are investigated. It is shown that the key role in the formation of deep-water circulation of the sea is played by the south
east flow, east cyclonic gyre, and Batumi anticyclonic eddy.
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Translated from Morskoi Gidrofizicheskii Zhurnal, No. 6, pp. 28–45, November–December, 2005. 相似文献
3.
Using AVISO satellite altimeter observations during 1993–2015 and a manual eddy detection method, a total of 276 anticyclonic rings and 242 cyclonic rings shed from the Kuroshio Extension(KE) were identified, and their three-dimensional(3D) anomaly structures were further reconstructd based on the Argo float data and the Japan Agency for Marine-Earth Science and Technology(JAMSTEC) cruise and buoy data through an interpolation method. It is found that the cyclonic(anticyclonic) rings presented consistent negative(positive) anomalies of potential temperature;meanwhile the relevant maximum anomaly center became increasingly shallow for the cyclonic rings whereas it went deeper for the anticyclonic rings as the potential temperature anomaly decreased from the west to the east. The above deepening or shoaling trend is associated with the zonal change of the depth of the main thermocline. Moreover, the composite cold ring between 140° and 150°E was found to exhibit a double-core vertical structure due to the existence of mode water with low potential vorticity. Specifically, a relatively large negative(positive) salinity anomaly and a small positive(negative) one appeared for the composite cyclonic(anticyclonic) ring at the depth above and below 600 m, respectively. The underlying driving force for the temperature and salinity anomaly of the composite rings was also attempted, which varies depending on the intensity of the background current and the temperature and salinity fields in different areas of the KE region, and the rings’ influences on the temperature and salinity could reach deeper than 1 000 m on average. 相似文献
4.
The analysis is performed on the basis of comparison of the hydrological characteristics of prestrait regions of the Sea of
Marmara. It is shown that, in summer, the Black-Sea waters are weakly mixed with the Mediterranean waters and the levels of
salinity in the prestrait regions differ by 0.6–0.9‰. In winter, the indicated difference increases and the level of salinity
near the entrance of Dardanelles reaches 29‰ and exceeds the level observed near the entrance of Bosporus by 5.5‰. In the
analyzed regions, we observe local temperature maxima and minima near the interface of two water masses. This is explained
by the presence of strong seasonal variations of temperature for the Black-Sea waters and their absence for the Mediterranean
waters. The physical mechanisms responsible for the seasonal variations of the intensity of transformations of the Black-Sea
waters are discussed.
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Translated from Morskoi Gidrofizicheskii Zhurnal, No. 2, pp. 49–55, March–April, 2007. 相似文献
5.
A reanalysis of atmospheric circulation in the Black Sea region is performed with a high spatial resolution of 25 × 25 km for the period from 1958 to 2001. Climatic wind speed fields are estimated, as are their spatial structure and seasonal variability. Mesoscale regions of cyclonic and anticyclonic speed vorticity, which are connected with edge effects and orography, are distinguished. To single out the monsoon mechanism in the annual votricity cycle, numerical experiments on the sensitivity that the regional atmospheric circulation has to the sea-surface temperature perturbations have been carried out. Large-scale regional peculiarities of the surface wind field are considered for different seasons. The vorticity of the surface wind speed and strength is assessed. Large annual average values of the vorticity are obtained which are comparable with the range of seasonal variability; they evidence the defining role that wind plays in the generation and seasonal variability, as well as the average cyclonic water circulation in the Black Sea. 相似文献
6.
Yugo Shimizu Takanori Iwao Ichiro Yasuda Shin-Ichi Ito Tomowo Watanabe Kazuyuki Uehara Nobuyuki Shikama Toshiya Nakano 《Journal of Oceanography》2004,60(2):453-462
Six newly developed floats, which were set to drift on the 26.7 σθ isopycnal surface and to profile temperature, salinity and pressure above 1000 dbar once a week, were deployed in the Oyashio
and Kuroshio Extension (KE) in order to examine the circulation, formation site and time scale of newly formed North Pacific
Intermediate Water (NPIW). The floats were deployed in February or May 2001, and the data from their deployments to December
2002 are analyzed here. Four of the six floats were deployed near the KE axis at around the first meander crest, and they
moved eastward to 157°E–176°W at latitudes of 30°N–45°N. The other two floats deployed in the Oyashio water with low-potential
vorticity near the south coast of Hokkaido moved southward to reach the KE front and then moved eastward to the same region
as the first four floats. The temperature and salinity at 26.7 σθ measured by the profiling floats indicate that the source waters of NPIW, Oyashio and Kuroshio waters are drastically mixed
and modified in the mixed water region west of 160°E. The floats were separated into the three paths east of 160°E between
the Kuroshio Extension front and the north of Water-Mass front (nearly subarctic front). New NPIW is judged to be formed along
these three paths since the vertical profiles of temperature and salinity are quite smooth, having a salinity minimum at about
26.7σθ along each path. Kuroshio-Oyashio isopycnal mixing ratios of the new NPIW are 7:3, 6:4 and 5:5 at 26.7σθ along the southern, middle and northern paths, respectively. Potential vorticity converges to about 14–15 × 10−11 m−1s−1 along these paths. The time scale of new NPIW formation is estimated to be 1–1.5 years from the merger of Oyashio and Kuroshio
waters to the formation of the new NPIW.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
7.
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
8.
The paper considers the thermohaline structure of Black Sea abyssal and near-bottom waters on the basis of exact measurements
recorded in recent years under the HYDROBLACK and COMSBLACK international projects. The surface water mass (along with the
cold mixed layer), the intermediate, abyssal, and near-bottom masses are identified. The upper boundary of deep waters is
defined as a depth level where the density ratio decreases down to 0.1 This depth roughly corresponds to the 900–1100 m depth
levels. Furthermore, the paper provides potential temperature and salinily values in the near-bottom layer, with an error
of, respectively, 0.002°C and 0.002‰, at most.
Translated by Vladimir A. Puchkin. 相似文献
9.
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
10.
The circulation of intermediate and deep waters in the Philippine Sea west of the Izu-Ogasawara-Mariana-Yap Ridge is estimated
with use of an inverse model applied to the World Ocean Circulation Experiment (WOCE) Hydrographic Program data set. Above
1500 m depth, the subtropical gyre is dominant, but the circulation is split in small cells below the thermocline, causing
multiple zonal inflows of intermediate waters toward the western boundary. The inflows along 20°N and 26°N carry the North
Pacific Intermediate Water (NPIW) of 11 × 109 kg s−1 in total, at the density range of 26.5σθ–36.7σ2 (approximately 500–1500 m depths), 8 × 109 kg s−1 of the NPIW circulate within the subtropical gyre, whereas the rest is conveyed to the tropics and the South China Sea. The
inflow south of 15°N carries the Tropical Salinity Minimum water of 35 × 109 kg s−1, nearly half of which return to the east through a narrow undercurrent at 15–17°N, and the rest is transported into the lower
part of the North Equatorial Countercurrent. Below 1500 m depth, the deep circulation regime is anti-cyclonic. At the density
range of 36.7σ2, – 45.845σ4 (approximately 1500–3500 m depths), deep waters of 17 × 109 kg s−1 flow northward, and three quarters of them return to the east at 16–24°N. The remainder flows further north of 24°N, then
turns eastward out of the Philippine Sea, together with a small amount of subarctic-origin North Pacific Deep Water (NPDW)
which enters the Philippine Sea through the gap between the Izu Ridge and Ogasawara Ridge. The full-depth structure and transportation
of the Kuroshio in total and net are also examined. It is suggested that low potential vorticity of the Subtropical Mode Water
is useful for distinguishing the net Kuroshio flow from recirculation flows.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
11.
On the basis of a simple stationary linear model and a contemporary nonlinear model, we study the mesoscale characteristics
of the fields of vertical velocity and vorticity of winds over the Black Sea. It is shown that, in the idealized case (without
taking into account the coastal features), the temperature contrast between the land and the sea in both models leads to the
formation of circulation cells in the coastal zone. However, the mountainous features prove to be the main factor affecting
the process of circulation for the actual synoptic situations. We present the map of monthly average vorticity of the surface
winds constructed according to the nonlinear mesoscale model with a resolution of 30 km for January 1996–2001.
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Translated from Morskoi Gidrofizicheskii Zhurnal, No. 1, pp. 52–61, January–February, 2005. 相似文献
12.
Numerical study on the interactions between a mesoscale eddy and a western boundary current 总被引:4,自引:3,他引:1
A reduced-gravity primitive equation eddy resolving model has been used to study the decay of a mesoscale eddy as it migrates
toward a western boundary current (WBC) region. The model results indicated that the gradient of the relative vorticity to
the east of the WBC is an important factor in the interaction between an eddy and a WBC. A circular eddy is deformed into
an elliptical form during the eddy–WBC interaction with the major axis of a cyclonic/anticyclonic eddy aligning in the NW/NNE
direction, respectively. Because of the difference in the major axes orientations for the cyclonic and anticyclonic eddies,
the kinetic energy transfer between a WBC and a particular eddy has very different behavior. A cyclonic eddy loses its energy
to the mean field, whereas an anticyclonic eddy can obtain energy from the mean flow during the WBC–eddy interaction. An anticyclonic
eddy, however, still decayed from losing its water and friction dissipation during the interaction period. 相似文献
13.
A new type of pycnostad has been identified in the western subtropical-subarctic transition region of the North Pacific, based
on the intensive hydrographic survey carried out in July, 2002. The potential density, temperature and salinity of the pycnostad
were found to be 26.5–26.7 σ
θ
, 5°–7°C and 33.5–33.9 psu respectively. The pycnostad is denser, colder and fresher than those of the North Pacific Central
Mode Water and different from those of other known mode waters in the North Pacific. The thickness of the pycnostad is comparable
to that of other mode waters, spreading over an area of at least 650 × 500 km around 43°N and 160°E in the western transition
region. Hence, we refer to the pycnostad as Transition Region Mode Water (TRMW). Oxygen data, geostrophic current speed and
climatology of mixed layer depth in the winter suggest that the TRMW is formed regularly in the deep winter mixed layer near
the region where it was observed. Analysis of surface heat flux also supports the idea and suggests that there is significant
interannual variability in the property of the TRMW. The TRMW is consistently distributed between the Subarctic Boundary and
the Subarctic Front. It is also characterized by a wide T-S range with similar density, which is the characteristic of such
a transition region between subtropical and subarctic water masses, which forms a density-compensating temperature and salinity
front. The frontal nature also tends to cause isopycnal intrusions within the pycnostad of the TRMW. 相似文献
14.
P矢量方法在南海夏季环流诊断计算中的应用 总被引:8,自引:4,他引:8
基于1998年6~7月南海调查航次的CTD资料,对南海环流采用最近发展的P矢量方法进行诊断计算.计算结果:黑潮向西入侵南海,然后做反气旋弯曲向东北方向流动,最终有通过巴士海峡流出南海的趋势.在南海北部存在一个气旋性环流,这个环流的强度和范围随深度增加而减小.该环流的冷中心位置随深度增加稍向南移.南海中部、越南以东海域存在一个明显的气旋涡和反气旋涡,尤其在200m及其以上水层均相当稳定,反气旋涡位于越南以东,其中心位置在11°53'N,111°50'E,气旋涡的中心位置在13°17'N,112°55'E,两者的尺度皆约为250km.吕宋岛西侧存在一个反气旋涡.在计算海区南部、巴拉望岛西南海域,100m以上层存在一个反气旋式涡.从各层流场分布均可以显示海流在西部强化的现象. 相似文献
15.
中尺度涡影响下的南海西部活性铝分布 总被引:1,自引:0,他引:1
To understand the distribution of aluminum(Al) under the influence of mesocale eddies in the western South China Sea(SCS), sea level anomaly, geostrophic current, environmental parameters and reactive Al were investigated in the western SCS in August 2013. The highest reactive Al concentration((180±64) nmol/L) was observed in the surface waters, indicating a substantial atmospheric input. Vertically, the reactive Al decreased from the surface high concentration to the subsurface minima at the depth of chlorophyll a(Chl a) maxima and then increased again with depth at most of the stations. The average concentration of reactive Al in the upper 100 m water column was significantly lower in the cyclonic eddy((137±6) nmol/L) as compared with that in the noneddy waters((180±21) nmol/L). By contrast, the average concentrations of Chl a and silicate in the upper 100 m water column were higher in the cyclonic eddy and lower in the anticyclonic eddy. There was a significant negative correlation between the average concentrations of reactive Al and Chl a in the upper 100 m water column. The vertical distribution of reactive Al and the negative correlation between reactive Al and Chl a both suggest that the reactive Al in the upper water column was significantly influenced by biological removal processes. Our results indicate that mesoscale eddies could regulate the distribution of reactive Al by influencing the primary production and phytoplankton community structure in the western SCS. 相似文献
16.
We discuss the results of the numerical experiment aimed at the simulation of the behavior of currents and transformations
of the temperature and salt modes in the Sevastopol Bay in January–February 1997. In the numerical analysis, we use actual
data on the velocity and direction of the wind, sea surface temperature, and the discharge of River Chernaya. It is shown
that the circulation and structure of hydrological fields are mainly connected with the direction of the wind, its intensity,
and variability in the course of time. Since the analyzed water area is shallow, the currents inside the bay undergo rapid
transformations (less than for an hour after changes in the wind). At the same time, the transformations of the thermohaline
fields are slower. Due to the inflow of fresh waters of River Chernaya and salt waters from the open sea through the strait,
the structure of thermohaline fields formed in the bay is nonuniform (both in the vertical and horizontal directions). The
distribution of salinity plays the main role in the formation of the vertical stratification, which is natural for the winter
season. Due to the process of freshening of water, a quite high vertical salinity gradient is formed in the upper layer of
the sea. As a result, the process of cooling does not lead to the appearance of convection and inversions of temperature are
formed in the case where warmer waters are located in the bottom layers.
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Translated from Morskoi Gidrofizicheskii Zhurnal, No. 2, pp. 60–76, March–April, 2005. 相似文献
17.
Using widespread conductivity–temperature–depth (CTD) data in the Philippine Sea and northern South China Sea near the Luzon
Strait together with altimeter data, we identified an intrusion of water from the Kuroshio into the South China Sea (SCS)
through the Luzon Strait in September 2008. The Kuroshio water obviously intruded into the SCS from 20 to 21°N, and existed
mainly in the upper 300 m. The intrusion water extended as far west as 117°E, then looped around in an anticyclonic eddy and
returned to the Philippine Sea further north. The dynamics of the Kuroshio intrusion are discussed using a 1.5-layer nonlinear
shallow-water reduced-gravity model. The analysis suggests that the strong cyclonic eddy to the east of the Kuroshio in September
2008 was of benefit to the intrusion event. 相似文献
18.
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
19.
Masashi Kusakabe Andrey Andreev Vyacheslav Lobanov Igor Zhabin Yuichiro Kumamoto Akihiro Murata 《Journal of Oceanography》2002,58(5):691-701
Data from the R/V Mirai cruise (May–June 2000) have been examined to discover how mesoscale processes associated with eddy dynamics direct affect
the water masses, the distributions and the vertical fluxes of the dissolved oxygen, nutrients and dissolved inorganic carbon
in the western subarctic Pacific. Using maps of the temperature, salinity, dissolved oxygen, nutrients, chlorophyll and sea-air
pCO2 difference we show that the boundaries of the anticyclone eddies in the study region were composed of high productivity coastal
Oyashio water. The coastal waters were wrapped around the anticyclone eddies (thus creating a high productivity belt) and
intruded inside of them. Using SeaWifs data we demonstrate that temporal variations in the position and the strength of anticyclone
eddies advected the Kuril island coastal high productivity waters to the pelagic part, resulting in temporal variations of
the chlorophyll in the Oyashio region. Computed vertical fluxes of the dissolved oxygen (DO), inorganic carbon (DIC) and silicate
show that the anticylonic eddies in the Kuroshio-Oyashio Zone are characterized by enhanced vertical fluxes of the DO and
DIC between the upper (σθ = 26.7–27.0) and lower (σθ = 27.1–27.5) intermediate layer, probably due to the intrusions of the Oyashio waters into the eddies.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
20.
This study is devoted to oceanographic features of the semi-enclosed Gulf of Aqaba, Red Sea. The data were recorded in winter—spring
1999 on the R/V Meteor cruise leg 44/2. Temperature and salinity profiles were measured at six positions (I—VI). The shipboard
NarrowBand Acoustic Doppler Current Profiler (NB ADCP) 150 kHz continuously recorded current profiles down to 350 m en route.
The research revealed that the current near the Strait of Tiran front (position VI) represents a semidiurnal signal of an
internal tide wave (∼12 h period; 0.2 ms−1 amplitude) that might be generated by the barotropic tide at the sill of the Strait. A sequence of cyclonic and anticyclonic
eddy pairs is found along the axis of the Gulf of Aqaba during winter-spring seasons. These sub-mesoscale signals are dominant
above the main thermocline and might be caused by wind forcing and the narrowness of the Gulf; it might remain in other seasons
with different dimensions in relation to the depth of thermocline. The total diameter of each pair was twice the baroclinic
Rossby radius (R ≈ 10 km). A single anti-cyclonic eddy was observed in the upper 300 m in the northern tip of the Gulf with a diameter of
about 5–8 km. 相似文献