共查询到20条相似文献,搜索用时 328 毫秒
1.
A number of significant hydrologicla and chemical parameters of the Black Sea shelf area have been identified and investigated:
the inter-annual variability of the mean annual and seasonal (winter and summer) values of the air and seawater temperatures
and salinity in the vicinity of Odessa; silicon and phosphate concentrations averaged over the north-western Black Sea shelf
area (NWBS); discharges of the Danube and Dnieper rivers; mean surface and near-bottom oxygen concentrations in summer acquired
through the analysis of the summarized data collected at three oceanographic stations occupied between Bolshoi Fontan and
the Tendra isthmus from the early 1950s up to date. From these data, the variability of the areas subject to oxygen deficit
in the near-bottom layer of the NWBS shelf during the summers of 1973–1994 has been assessed. Predominant oscillation periods
and trends in the inter-annual variability of the studied parameters have been revealed and their relationship and climatic
dependence has been demonstrated.
Translated by Vladimir A. Puchkin. 相似文献
2.
The effect of a tidal cycle on the dynamics of nutrients in a tidal estuary in the Seto Inland Sea, Japan 总被引:4,自引:0,他引:4
Shigeru Montani Paolo Magni Megumi Shimamoto Nao Abe Koichi Okutani 《Journal of Oceanography》1998,54(1):65-76
A 24 hour time series survey was carried out during a spring tide (tidal range ca.2 m) of May 1995 on a tidal estuary in the
Seto Inland Sea, Japan, in the context of an integrated program planned to quantify the dynamics of biophilic elements (carbon,
nitrogen and phosphorus) and the roles played by the macrobenthos on the processes. Three stations were set along a transect
line of about 1.4 km, which linked the river to the rear to the innermost part of the subtidal zone. Every hour, at each station,
measurements were made of surface water temperature, salinity and dissolved oxygen concentration, and surface water was collected
for the determination of nutrients [NH4
+−N, (NO3
−+NO2
−)−N, PO4
3−−P and Si (OH)4−Si]. During the ebb flow, riverine input of silicate and nitrate+nitrite significantly increased the concentrations of both
the intertidal and the subtidal stations. Conversely, during the high tide, river nutrient concentrations were lowered by
the mixing of fresh water with sea water. As a result, best (inverse) correlations were found at the river station for salinity
against silicate (y=-2.9 Sal.+110.7,r
2=0.879) and nitrate+nitrite (y=-1.3 Sal.+48.4,r
2=0.796). In contrast, ammonium nitrogen concentrations were higher at intermediate salinities. Indeed, no significant correlation
was found between salinity and ammonium. The effect of the macrobenthos, which is abundant on the intertidal flat, is discussed
as a biological component that influences the processes of nutrient regeneration within the estuary. The effect of the tidal
amplitude is an important one in determining the extent of the variations in nutrient concentrations at all three stations,
which were stronger between the lower low tide and the higher high tide. 相似文献
3.
By using the archival hydrological data for 1955–1998, we analyze the trends of deep-water thermohaline characteristics of
the Black Sea and their interannual and decadal variability. It was discovered that the level of salinity increased at depths
greater than 1000 m in the west part of the sea from the mid-1950-s till the early 1980s and the opposite trend was observed
for the next 15–20 yr. The average rate of increase in the deep-water salinity between 1960 and 1980 and its decrease after
1980 was equal to 0.05‰ per 20 yr. These facts demonstrate that the water exchange through Bosporus was intensified for the
first 25 yr of the analyzed period and weakened for the next 20 yr. The interannual variability with a typical period of 6.5
yr and a quasi-20-yr periodicity are detected against the background of the parabolic trend.
__________
Translated from Morskoi Gidrofizicheskii Zhurnal, No. 4, pp. 18–30, July–August, 2006. 相似文献
4.
The aim of the present work is to reconstruct the space and time variability of the three-dimensional fields of currents,
temperature, salinity, and density in the Sevastopol Bay under the influence of the actual external factors in 1999. For this
purpose, we use a version of the numerical multilayer model on the σ-coordinates. A vast array of the data of observations
accumulated as a result of regular monitoring of the Sevastopol Bay contains, in particular, the data on the sea-surface temperature
measured with six-hour intervals (at the hydrometeorological station located near the center of the bay) and almost monthly
vertical profiles of temperature and salinity obtained at seven hydrological stations. The comparison of the numerical results
with the data of observations enables us to conclude that, in general, the model fairly correctly describes the space structure
and rearrangements of the fields of temperature and salinity. Among the most important distinctions, we can mention the fact
that the fresh river water penetrating into the bay is mixed with seawater faster than predicted by the model. We also discuss
the causes of these distinctions.
Translated from Morskoi Gidrofizicheskii Zhurnal, No. 5, pp. 23–39, September–October, 2008. 相似文献
5.
Seasonal evolution of surface mixed layer in the Northern Arabian Sea (NAS) between 17° N–20.5° N and 59° E-69° E was observed
by using Argo float daily data for about 9 months, from April 2002 through December 2002. Results showed that during April
- May mixed layer shoaled due to light winds, clear sky and intense solar insolation. Sea surface temperature (SST) rose by
2.3 °C and ocean gained an average of 99.8 Wm−2. Mixed layer reached maximum depth of about 71 m during June - September owing to strong winds and cloudy skies. Ocean gained
abnormally low ∼18 Wm−2 and SST dropped by 3.4 °C. During the inter monsoon period, October, mixed layer shoaled and maintained a depth of 20 to
30 m. November - December was accompanied by moderate winds, dropping of SST by 1.5 °C and ocean lost an average of 52.5 Wm−2. Mixed layer deepened gradually reaching a maximum of 62 m in December. Analysis of surface fluxes and winds suggested that
winds and fluxes are the dominating factors causing deepening of mixed layer during summer and winter monsoon periods respectively.
Relatively high correlation between MLD, net heat flux and wind speed revealed that short term variability of MLD coincided
well with short term variability of surface forcing. 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.
We collected surface water along the 142nd E meridian from Tasmania to Antarctica in December 1999. We measured temperature,
salinity and total chlorophyll a; additionally, we collected suspended particle size fractions and used fluorometric analysis to determine the quantity of
chlorophyll a in each of four cell size classes: picoplankton (<3 μm), two nanoplankton fractions (3–10 μm and 10–20 μm) and microplankton
(> 20 μm). Changes in temperature and salinity show that we crossed 6 water masses separated by 5 fronts. We found low abundance
(<0.2 mg m−3) of chlorophyll in all size classes, with the exception of higher values near the continent (0.2 to 0.4 mg m−3). Lowest chlorophyll values (<0.1 mg m−3) were found in the Polar Frontal Zone (51° to 54°S). Microplankton made up the largest portion of total chlorophyll throughout
most of the region. We conclude that biomass of all phytoplankton fractions, especially pico-and nanoplankton, was constrained
by limiting factors, most probably iron, throughout the region and that ecosystem dynamics within a zone are not circumpolar
but are regionalized within sectors. 相似文献
8.
Hydrographic data collected from Gulf of Aden since 1920 have been compiled to identify and refine the definitions of water
masses in the Gulf of Aden (GA) and to describe their spatio-temporal variability. Four water masses have been identified
based on their θ-S characteristics. The Red Sea Water (RSW) that flows from the Red Sea is the most prominent water in the GA; this occupies
about 37% of the total volume of Gulf of Aden. The Gulf of Aden Surface Water (∼3%) forms as a mixture of local water and
the water from western Arabian Sea during winter and Red Sea surface water during summer. The intermediate water, identified
as Gulf of Aden Intermediate Water (GAIW), occupies about 9% of the total volume of GA; a characteristic salinity minimum
is associated with it at σθ=26.50 kg m−3. The northward spread of sub-tropical subsurface water from the south appears to be the major source of GAIW. The bottom
water, named Gulf of Aden Bottom Water, showed the least variability. It was formed due to the mixing of Red Sea Water and
water of southern origin. Mixing triangles have been used to analyze the composition of water in the GA. 相似文献
9.
Impact of the winter cooling on the variability of the thermohaline characteristics of the active layer in the Black Sea 总被引:1,自引:0,他引:1
The influence of the winter atmospheric forcing on the interannual variability of the Black Sea’s active layer’s thermohaline
structure during 1982–2008 is investigated. The results are based on the combined analysis of the hydrological measurements
from a ship, satellite measurements of the sea’s surface temperature (SST), and the NCEP/NCAR reanalysis data for the surface
air temperature (SAT). A high correlation between the variability of the winter mean SST/SAT and the thermohaline characteristics
of the active layer during the following warm season was found. It is shown that the winter atmospheric forcing significantly
affects the variability of the temperature, salinity, and density down to the 150–200 m depth, and this has to be considered
in the analysis of the interannual and long-term variability of the Black Sea’s active layer. 相似文献
10.
Richard A. Feely Christopher L. Sabine Reiner Schlitzer John L. Bullister Sabine Mecking Dana Greeley 《Journal of Oceanography》2004,60(1):45-52
As a part of the JGOFS synthesis and modeling project, researchers have been working to synthesize the WOCE/JGOFS/DOE/NOAA
global CO2 survey data to better understand carbon cycling processes in the oceans. Working with international investigators we have
compiled a Pacific Ocean data set with over 35,000 unique samples analyzed for at least two carbon species, oxygen, nutrients,
chlorofluorocarbon (CFC) tracers, and hydrographic parameters. We use these data here to estimate in-situ oxygen utilization
rates (OUR) and organic carbon remineralization rates within the upper water column of the Pacific Ocean. OURs are derived
from the observed apparent oxygen utilization (AOU) and the water age estimates based on CFCs in the upper water and natural
radiocarbon in deep waters. The rates are generally highest just below the euphotic zone and decrease with depth to values
that are much lower and nearly constant in water deeper than 1200 m. OURs ranged from about 0.02–10 μmol kg−1yr−1 in the upper water masses from about 100–1000 m, and averaged = 0.10 μmol kg−1yr−1 in deep waters below 1200 m. The OUR data can be used to directly estimate organic carbon remineralization rates using the
C:O Redfield ratio given in Anderson and Sarmiento (1994). When these rates are integrated we obtain an estimate of 5.3 ±
1 Pg C yr−1 for the remineralization of organic carbon in the upper water column of the Pacific Ocean.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
11.
Tomoharu Senjyu Noriko Asano Masaji Matsuyama Takashi Ishimaru 《Journal of Oceanography》1998,54(1):29-44
Intermediate intrusion of low salinity water (LSW) into Sagami Bay was investigated on the basis of CTD data taken in Sagami
Bay and off the Boso Peninsula in 1993–1994. In October 1993, water of low temperature (<7.0°C), low salinity (<34.20 psu)
and high dissolved oxygen concentration (>3.5 ml I−1) intruded along the isopycnal surface of {ie29-1} at depths of 320–500 m from the Oshima East Channel to the center of the
bay. On the other hand, the LSW was absent in Sagami Bay in the period of September–November 1994, though it was always found
to the south off the Boso Peninsula. Salinity and dissolved oxygen distributions on relevant isopycnal surfaces and water
characteristics of LSW cores revealed that the LSW intruded from the south off the Boso Peninsula to Sagami Bay through the
Oshima East Channel. The LSW cores were distributed on the continental slope along 500–1000 m isobaths and its onshore-offshore
scales were two to three times the internal deformation radius. Initial phosphate concentrations in the LSW revealed its origin
in the northern seas. These facts suggest that the observed LSW is the submerged Oyashio Water and it flows southwestward
along the continental slope as a density current in the rotating fluid. The variation of the LSW near the center of Sagami
Bay is closely related to the Kuroshio flow path. The duration of LSW in Sagami Bay is 0.5 to 1.5 months. 相似文献
12.
The petrophysical properties of sediment drill core samples recovered from the Sardinian margin and the abyssal plain of the
Southern Tyrrhenian Basin were used to estimate the downhole change in porosity and rates of deposition and mass accumulation.
We calculated how the deposited material has changed its thickness as a function of depth, and corrected the thickness for
the compaction. The corresponding porosity variation with depth for terrigenous and pelagic sediments and evaporites was modelled
according to an exponential law. The mass accumulation rate for the Plio-Quaternary is on average 4.8×104 kg m−2 my−1 on the Sardinian margin and for the Pliocene in the abyssal plain. In the latter area, the Quaternary attains its greatest
thickness and a mass accumulation rate of 11–40×104 kg m−2 my−1. The basement response to sediment loading was calculated with Airy-type backstripping. On the lower part of the Sardinian
margin, the basement subsidence rate due to sediment loading has decreased from a value of 300 m my−1 in the Tortonian and during the Messinian salinity crisis (7.0–5.33 Ma) to about 5 m my−1 in the Plio-Quaternary. In contrast, on the abyssal plain this rate has changed from 8–50 m my−1 during the period 3.6–0.46 Ma, to 95–130 m my−1 since 0.46 Ma, with the largest values in the Marsili Basin. The correlation between age and the depth to the basement corrected
for the loading of the sediment in the ocean domain of the Tyrrhenian Basin argues for a young age of basin formation. 相似文献
13.
The seasonal abundance of the dominant dinoflagellate, Ceratium fusus, was investigated from January 2000 to December 2003 in a coastal region of Sagami Bay, Japan. The growth of this species
was also examined under laboratory conditions. In Sagami Bay, C. fusus increased significantly from April to September, and decreased from November to February, though it was found at all times
through out the observation period. C. fusus increased markedly in September 2001 and August 2003 after heavy rainfalls that produced pycnoclines. Rapid growth was observed
over a salinity range of 24 to 30, with the highest specific rate of 0.59 d−1 measured under the following conditions: salinity 27, temperature 24°C, photon irradiance 600 μmol m−2s−1. The growth rate of C. fusus increased with increasing irradiance from 58 to 216 μmol m−2s−1, plateauing between 216 and 796 μmol m−2s−1 under all temperature and salinity treatments (except at a temperature of 12°C). Both field and laboratory experiments indicated
that C. fusus has the ability to grow under wide ranges of water temperatures (14–28°C), salinities (20–34), and photon irradiance (50–800
μmol m−2s−1); it is also able to grow at low nutrient concentrations. This physiological flexibility ensures that populations persist
when bloom conditions come to an end. 相似文献
14.
In order to examine the formation, distribution and transport of North Pacific Intermediate Water (NPIW), repeated hydrographic
observations along several lines in the western North Pacific were carried out in the period from 1996 to 2001. NPIW formation
can be described as follows: (1) Oyashio water extends south of the Subarctic Boundary and meets Kuroshio water in intermediate
layers; (2) active mixing between Oyashio and Kuroshio waters occurs in intermediate layers; (3) the mixing of Oyashio and
Kuroshio waters and salinity minimum formation around the potential density of 26.8σθ proceed to the east. It is found that Kuroshio water flows eastward even in the region north of 40°N across the 165°E line,
showing that Kuroshio water extends north of the Subarctic Boundary. Volume transports of Oyashio and Kuroshio components
(relative to 2000 dbar) integrated in the potential density range of 26.6–27.4σθ along the Kuroshio Extension across 152°E–165°E
are estimated to be 7–8 Sv (106 m3s−1) and 9–10 Sv, respectively, which is consistent with recent work.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
15.
Hydrographic conditions in the Tsushima Strait revisited 总被引:1,自引:1,他引:0
Long-term averaged temperature and salinity distributions in the Tsushima Strait are investigated on the basis of a concurrent
dataset of the eastern and western channels during 1971–2000. Both temperature and salinity show a clear seasonal variation
with weak and strong stratifications in December–April and June–October, respectively. The largest standard deviations occur
in summer around the thermocline for temperature and in the surface layer for salinity. This indicates large interannual variability
in the development of a thermocline and low salinity water advection from the East China Sea. The water masses in both channels
are distinctly different from each other; the water in the western channel is generally colder and fresher than that in the
eastern channel throughout the year. Baroclinic transport based on the density distributions shows a seasonal variation with
a single peak in August for the eastern channel and double peaks in April and August for the western channel. However, this
cannot explain the seasonal variation in the total volume transport estimated from the sea level differences across the channels.
The spatial distribution of baroclinic transport shows a year-round negative transport towards the East China Sea behind the
Iki Island in the eastern part of the eastern channel. This negative transport reflects the baroclinic structure between the
offshore Tsushima Current Water and cold coastal water. The corresponding southwestward currents are found in both Acoustic
Doppler Current Profiler (ADCP) and high frequency (HF) radars observations. 相似文献
16.
An-Yi Tsai Gwo-Ching Gong Kuo-Ping Chiang Chien-Fu Chao Herng-Ru Guo 《Journal of Oceanography》2011,67(6):725-737
The spatial distribution of heterotrophic ciliates, environmental factors and potential food items (bacteria, Synechococcus spp. and nanoflagellates) were measured in the East China Sea to examine which variables contributed importantly to the long-term
distribution of ciliates between 1998 and 2007. In July 1998 and June 2003, heterotrophic ciliates were found to be abundant
(1,000–2,000 × 103 cells m−3) in regions where surface salinity <32 but extremely low (<500 × 103 cells m−3) in shelf waters of surface salinity >32. After August 2003, shortly after the completion of the Three Gorges Dam, we found
no significant areal differences in the abundance of heterotrophic ciliates (HC). However, we found a significantly negative
correlation between temperature and HC abundance of surface water after the completion of the dam, suggesting that temperature
had a greater influence on HC abundance, once the original saline state had changed. For the long-term trends on the vertical
distribution of HC, their abundance was significantly higher in the upper 50 m of the water column than at either 75 or 100 m.
Abundance of Synechococcus spp. at these levels varied significantly in regions of surface salinity <32, suggesting that ciliates and picophytoplankton
contribute greatly to mediating the transfer of organic matter to higher trophic levels in this marine ecosystem. 相似文献
17.
The mechanism by which nutrient is supplied to a warm-core ring (WCR) was investigated in order to understand the greater
productivity of WCR than that of the Kuroshio, where the WCR originattes. A single WCR was observed in January and May, 1997.
The thermostad (a layer of isothermal and isohaline water) of the WCR had different properties from January to May, the differences:
Δwater temperature: −0.698°C, Δsalinity: −0.048, Δsigma θ: +0.072, Δnitrite+nitrate-N: +1.83 μM, Δphosphate: +0.011 μM and
Δsilicate: +3.2 μM. We examined three possible mechanisms for nutrient supply to WCR in winter, namely: 1) inflow of the Oyashio
surface water into WCR; 2) isopycnal mixing with Oyashio water; 3) entrainment of the water below the WCR into the WCR. The
results were as follows: 1) When the decrease of salinity was due to the inflow of the Oyashio surface water, the increase
of nutrients (nitrite+nitrate-N, phosphate-P and silicate-Si) was estimated to be only 17–27% of the observed increase. 2)
When the decrease of salinity was due to isopycnal mixing, the increase of nutrients was estimated to be 30–42% of the observed
increase. 3) When the decrease of salinity in the WCR in May was due to entrainment of the water below the WCR in winter by
convection, the mixing depth was calculated be 620 m according to the salt budget. The increase of nutrients in this case
was calculated to be 82–95% of the observed increase. The main mechanism of nutrient supply to WCR was concluded to be due
to the entrainment of the water below the WCR by winter mixing.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
18.
Seasonal and interannual variations in physicochemical properties were investigated in the neritic area of Sagami Bay, Kanagawa,
Japan, from December 2000 to December 2005. Physicochemical properties (i.e. temperature, salinity, density, dissolved oxygen
and dissolved inorganic nutrient concentration) revealed clear seasonal variations, which were similar to each other during
all 5 years. Temperature, salinity and dissolved inorganic nutrients showed rapid, drastic variations within a few days and/or
weeks. These variations are related to sea levels, principally due to the shifting effects of the Kuroshio Current axis: they
were strongly affected by the Kuroshio Water and other waters, when sea level difference was greater than ca. 35 cm and lower
than ca. 15 cm, respectively. Temperature difference (DF
T
) increased with sea level difference, and the difference of salinity and dissolved inorganic nutrients (NH4
+-N, NO3
−+NO2
−-N, NH4
++NO3
−+NO2
−-N, PO4
3−-P and SiO2-Si) increased and decreased with DF
T
, respectively. All these correlations are significant. Total dissolved inorganic nitrogen (N), phosphate (P) and silicate
(Si) revealed seasonal variations in the ranges of 0.57–16.08, 0.0070–0.91 and 0.22–46.38 μM, respectively. From the regression equations between these elements allowed the following relation to be obtained; Si:N:P
= 14.8:13.4:1. Dissolved inorganic nutrients were characterized by Si and/or P deficiency, especially in the upper layer (0–20
m depth) during summer. Single and/or combined elements are discussed on the basis of potential and stoichiometric nutrient
limitations, which could restrict phytoplankton (diatom) growth as a limiting factor. 相似文献
19.
Changyou Wang Xiulin Wang Bodong Wang Chuansong Zhang Xiaoyong Shi Chenjian Zhu 《Oceanology》2009,49(1):64-72
Dissolved concentrations of Cu, Pb, Zn, and Cd were measured in the Changjiang estuary and its adjacent waters. The results
indicate that the ranges of dissolved heavy metals in the studied waters are as follows: Cu = 1.0−6.9 μg/L, Pb = 0.10−0.39
μg/L, Zn = 3.2−9.1 μg/L, and Cd = 0.011−0.049 μg/L. The behavior of the dissolved Cu was essentially conservative, but a high
scatter was observed for the high salinity samples, and it is the same with Zn and Pb. The overall concentrations of dissolved
Cd increase with the salinity. There were no differences between the surface, middle, and bottom layer for Cu, Pb, Zn, and
Cd. Seasonal changes of their averages were not obvious on the whole. River discharges, sedimentary dynamics, and biological
processes might determine the profiles of heavy metals.
The text was submitted by the authors in English. 相似文献
20.
In order to reconstruct the large-scale temperature and salinity fields by the method of optimal interpolation of the archival
data, we compute the correlation functions and analyze the space and time variations of the statistical structure of the fields.
On the sea surface, the thermohaline fields are spatially inhomogeneous. Thus, the correlation functions are anisotropic in
the region of the northwest shelf and close to isotropic in the inner parts of the sea. The values of correlation length vary
from season to season. In the layer of pycnocline, the temperature and salinity fields are anisotropic. In the zonal direction,
the correlation length is 2–3 times greater than in the meridional direction. The indicated anisotropy becomes stronger in
the winter season and weaker in the summer season as a consequence of the seasonal variability of large-scale circulation.
We study the dependence of the error of reconstruction of the fields by the method of optimal interpolation on the form of
approximation of the correlation functions with regard for anisotropy.
__________
Translated from Morskoi Gidrofizicheskii Zhurnal, No. 1, pp. 51–65, January–February, 2008. 相似文献