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1.
Bottom sediment was analysed, via grab, trawl and underwater photography in 1991–1992 in the Barents, White, Kara, Norwegian and Greenland Seas, and the large scale features of macrobenthos distribution are described. The maps of alpha-diversity, biomass and trophic zone distribution on the investigated shelf are presented. Statistical assessment of the bottom community structure changes during the last 60–70 years for the Barents Sea area is presented. It is shown that on regional and transregional levels the researched communities are of natural undisturbed character and that the revealed changes may be both the result of natural processes or sampling errors. Local disturbances of benthos composition and structure, supposedly caused by man, are found to be rare not far from the Novaya Zemlya and Murman coasts. 相似文献
2.
The physical and biological environment of the Barents Sea is characterised by large variability on a wide range of scales.
Results from a numerical ocean model, SINMOD, are presented showing that the physical variability is partly forced by changes
in annual net ice import. The mean contribution from ice import in the simulation period (1979–2007) is about 40% of the total
amount of ice melted each year. The annual ice import into the Barents Sea varies between 143 and 1,236 km3, and this causes a substantial variability in the amount of annual ice melt in the Barents Sea. This in turn impacts the
freshwater content. The simulated freshwater contribution from ice is 0.02 Sv on average and 0.04 Sv at maximum. When mixed
into a mean net Atlantic Water (AW) inflow of 1.1 Sv with a salinity of 35.1, this freshwater addition decreases the salinity
of the modified AW to 34.4 and 33.9 for the mean and maximum freshwater fluxes, respectively. Ice import may thus be important
for the Barents Sea production of Arctic Ocean halocline water which has salinity of about 34.5. The changes in the ice melt
the following summer due to ice import also affect the formation of dense water in the Barents Sea by changing stratification,
altering the vertical mixing rates and affecting heat loss from the warm AW. The model results thus indicate that ice import
from the Arctic has a great impact on water mass modification in the Barents Sea which in turn impacts the ventilation of
the Arctic Ocean. 相似文献
3.
Vincent Le Fouest Clare PostlethwaiteMiguel Angel Morales Maqueda Simon BélangerMarcel Babin 《Continental Shelf Research》2011,31(17):1869-1879
Tides and wind-driven mixing play a major role in promoting post-bloom productivity in subarctic shelf seas. Whether this is also true in the high Arctic remains unknown. This question is particularly relevant in a context of increasing Arctic Ocean stratification in response to global climatic change. We have used a three-dimensional ocean-sea ice-plankton ecosystem model to assess the contribution of tides and strong wind events to summer (June-August 2001) primary production in the Barents Sea. Tides are responsible for 20% (60% locally) of the post-bloom primary production above Svalbard Bank and east of the Kola Peninsula. By contrast, more than 9% of the primary production is due to winds faster than 8 m s−1 in the central Barents Sea. Locally, this contribution reaches 25%. In the marginal ice zone, both tides and wind events have only a limited effect on primary production (<2%). Removing tides or winds faster than 8 m s−1 promotes a regime more sustained by regenerated production with a f-ratio (i.e. the proportion of nitrate-based “new” primary production in the total primary production) that decreases by up to 26% (east of the Kola Peninsula) or 35% (central Barents Sea), respectively. When integrated over all Barents Sea sub-regions, tides and strong wind events account, respectively, for 6.8% (1.55 Tg C; 1 Tg C=1012 g C) and 4.1% (0.93 Tg C) of the post-bloom primary production (22.6 Tg C). To put this in context, this contribution to summer primary production is equivalent to the spring bloom integrated over the Svalbard area. Tides and winds are significant drivers of summer plankton productivity in the Barents Sea. 相似文献
4.
Literary data have been used to assess the inflow of petroleum hydrocarbons (with river runoff, precipitation, wastewaters, sea transport, and at ice thawing) into different regions of the White Sea. The hydroecological CNPSi-model was used as an instrument to reproduce the annual dynamics of hydrocarbon concentrations at their parallel inflow and subsequent transformation in the waters of the nine White Sea regions (the bays of Kandalaksha, Onega, Dvina, and Mezen; the Solovetskie Islands; the deep-water part: Bassein, Gorlo, Voronka, and Chupa Bay). The calculations were based on normal annual values of monthly variations of water temperature, light intensity, and transparency, the morphometric parameters of the regions (water areas, mean depths, and water volumes) and water exchange between the regions and with the Barents Sea (calculated by a hydrodynamic model). The calculated concentrations of hydrocarbons, the biomasses and activity characteristics of hydrocarbon-oxidizing bacteria have been analyzed (their values were estimated for the 2-m surface water layer). The results of calculations were used to evaluate hydrocarbon balances for regions and the sea as a whole. The calculations demonstrate the balanced character of hydrocarbon fluxes, the balance discrepancy for the regions being <0.1–16.1%. 相似文献
5.
W. P. Budgell 《Ocean Dynamics》2005,55(3-4):370-387
A dynamic–thermodynamic sea ice model has been coupled to a three-dimensional ocean general circulation model for the purpose of conducting ocean climate dynamical downscaling experiments for the Barents Sea region. To assess model performance and suitability for such an application, the coupled model has been used to conduct a hindcast for the period 1990–2002. A comparison with available observations shows that the model successfully tracks seasonal and inter-annual variability in the ocean temperature field and that the simulated horizontal and vertical distribution of temperature are in good agreement with observations. The model results follow the seasonal and inter-annual variability in sea ice cover in the region, with the exception that the model results show too much ice melting in the northern Barents Sea during summer. The spatial distribution of the winter simulated sea ice cover is in close agreement with observations. Modelled temperatures and ice concentrations in the central Barents Sea are biased too high and too low, respectively. The probable cause is too high inflow of Atlantic Water into the Barents. The seasonal and inter-annual fluctuations in temperature and sea ice cover in the central Barents are, however, in excellent agreement with observations. Salt release during the freezing process in the numerical simulation exhibits considerable inter-annual variability and tends to vary in an opposite manner to the net inflow volume flux at the western entrance of the Barents Sea. Overall, the model produces realistic ice-ocean seasonal and inter-annual variability and should prove to be a useful tool for dynamical downscaling applications. 相似文献
6.
The principles and methods of comprehensive evaluative mapping of seawater areas are considered using the Barents Sea as an example. The areas are classified using a digital map database represented by a series of electronic thematic maps. The digital thematic maps are based on a raster version of a geographic information system (GIS). 相似文献
7.
Barthel Knut Daewel Ute Pushpadas Dhanya Schrum Corinna &#;rthun Marius Wehde Henning 《Ocean Dynamics》2012,62(10):1457-1470
This article presents some advantages using a shape-preserving total variation diminishing (TVD) advection scheme in an ecosystem model. The superbee flux-limiter has been used to the second-order Lax–Wendroff advection scheme to make it TVD. We performed simulations for three shelf sea regions with different characteristic time scales, namely, the North Sea, the Barents Sea, and the Baltic Sea. To explore the advantages, we also performed reference runs with the much simpler and computationally cheaper upwind advection scheme. Frontal structures are much better resolved with the TVD scheme. The bottom salinity in the Baltic Sea stays at realistic values throughout the 10-year simulation with the TVD scheme, while with the upwind scheme, it drifts towards lower values and the permanent haline stratification in the Baltic is almost completely eroded within one seasonal cycle. Only when applying TVD for both the vertical and horizontal advections the model succeeded to preserve haline stratification in the decadal simulation. Lower trophic level patterns are far better reproduced with the TVD scheme, and for the estimated cod larval survival, the advantages seem to be even stronger. Simulations using the TVD-derived prey fields identified distinct regions such as Dogger Bank to favor potential larvae survival (PLS), which did not appear as particularly favorable in the upstream simulations. The TVD scheme needs about 25 % more time on the central processing unit (CPU) in case of a pure hydrodynamic setup with only two scalar state variables (Barents Sea application). The additional CPU time cost increases for a coupled physical–biological model application with a large number of state variables. However, this is more than compensated by all the advantages found, and, hence, we conclude that it is worthwhile to use the TVD scheme in our ecosystem model.
相似文献8.
Distribution and abundance of zooplankton in the North Sea during the Autumn Circulation Experiment (October 1987–March 1988) were examined. From shipboard egg production incubations and the distributions of eggs, nauplii and females, the productivity of various copepod species was described. Against the background of surface temperature, salinity and chlorophyll-a distributions, major seasonal changes in plankton biomass distributions and specific production of copepods were seen. High biomass levels in October rapidly declined into November and January, especially in the north. These changes were followed by early (January/February) production and biomass increases in the southeastern North Sea. Although lowest between November and January, depending on species and location, production continued for many copepod species throughout the winter, despite low temperatures and large predator populations. It was concluded that winter survival of herring larvae and other predators was enhanced by herbivore production in the southeastern North Sea, and that in the north, low herbivore production, competition and predation decreased the probabilities of predator survival. Copepod overwintering strategies and the implications of winter herbivore production and predator abundance for later plankton production processes are discussed. 相似文献
9.
Knut Barthel Ute Daewel Dhanya Pushpadas Corinna Schrum Marius ?rthun Henning Wehde 《Ocean Dynamics》2012,62(10-12):1457-1470
This article presents some advantages using a shape-preserving total variation diminishing (TVD) advection scheme in an ecosystem model. The superbee flux-limiter has been used to the second-order Lax–Wendroff advection scheme to make it TVD. We performed simulations for three shelf sea regions with different characteristic time scales, namely, the North Sea, the Barents Sea, and the Baltic Sea. To explore the advantages, we also performed reference runs with the much simpler and computationally cheaper upwind advection scheme. Frontal structures are much better resolved with the TVD scheme. The bottom salinity in the Baltic Sea stays at realistic values throughout the 10-year simulation with the TVD scheme, while with the upwind scheme, it drifts towards lower values and the permanent haline stratification in the Baltic is almost completely eroded within one seasonal cycle. Only when applying TVD for both the vertical and horizontal advections the model succeeded to preserve haline stratification in the decadal simulation. Lower trophic level patterns are far better reproduced with the TVD scheme, and for the estimated cod larval survival, the advantages seem to be even stronger. Simulations using the TVD-derived prey fields identified distinct regions such as Dogger Bank to favor potential larvae survival (PLS), which did not appear as particularly favorable in the upstream simulations. The TVD scheme needs about 25?% more time on the central processing unit (CPU) in case of a pure hydrodynamic setup with only two scalar state variables (Barents Sea application). The additional CPU time cost increases for a coupled physical–biological model application with a large number of state variables. However, this is more than compensated by all the advantages found, and, hence, we conclude that it is worthwhile to use the TVD scheme in our ecosystem model. 相似文献
10.
—?A crustal velocity model has been developed for Fennoscandia, the Baltic shield and adjacent areas. This model represents a simplified average of various models developed for parts of this region. We show that P-wave travel times calculated with this model provide an excellent fit to observations at the Fennoscandian, KRSC and IRIS station networks for a set of seismic events with known or very well-constrained locations. The station-event paths cover large parts of Western Russia and the Barents Sea, thus indicating that this model, which we denote the Barents model, is appropriate for this entire region. We show by examples that significant improvements in event location precision can be achieved compared to using the IASPEI model. We finally use the Barents model to calculate locations of recent small seismic events in the Novaya Zemlya region of interest in a CTBT monitoring context. 相似文献
11.
Yoichiro Fujii 《Pure and Applied Geophysics》1995,144(1):19-37
In order to study characteristics of horizontal crustal strains, we divide the Japanese Islands into 14 tectonic provinces
consistent with the suggestion given byMatsuda (1990). We calculate frequency distribution of strain rates using the results of the Precise Control Survey initiated by
the Geographical Survey Institute in 1973. This survey is a revision of old first- and second-order triangulation networks
by trilateration. The principal axes and principal strains inside all the geodetic triangles are deduced from the comparison
of the old triangulation and the new trilateration networks. The maximum shear strain rates are calculated by dividing the
accumulated strains with the time intervals. The frequency distribution of strain rates is counted for each tectonic province
and for the entire Japanese Islands.
It is proved that the maximum shear strain rate with highest frequency ranges from 0.10–0.15 microstrain/a for 4409 data in
the Japanese Islands. The mean value of the strain rates throughout the Japanese Islands is deduced to be 0.18 microstrain/a.
We also calculated a mean value of strain rates for each tectonic province. Comparison is made between mean geodetic strain
rates in the provinces and Quaternary strain rates estimated by geomorphic data. It is found that 0.3–0.4 microstrain/a of
the highest order strain rate is now prevailing in the Izu province, the south Fossa-Magna collision zone, and some special
provinces along the eastern part of the Japan Sea coast. 相似文献
12.
Global coupled climate models are generally capable of reproducing the observed trends in the globally averaged atmospheric
temperature. However, the global models do not perform as well on regional scales. Here, we present results from a 20-year,
high-resolution ocean model experiment for the Atlantic and Arctic Oceans. The atmospheric forcing is taken from the final
20 years of a twentieth-century control run with a coupled atmosphere–ocean general circulation model. The ocean model results
from the regional ocean model are validated using observations of hydrography from repeat cruises in the Barents Sea. Validation
is performed for average quantities and for probability distributions in space and time. The validation results reveal that,
though the regional model is forced by a coupled global model that has a noticeable sea ice bias in the Barents Sea, the hydrography
and its variability are reproduced with an encouraging quality. We attribute this improvement to the realistic transport of
warm, salty waters into the Barents Sea in the regional model. These lateral fluxes in the ocean are severely underestimated
by the global model. The added value with the regional model that we have documented here lends hope to advance the quality
of oceanic climate change impact studies. 相似文献
13.
14.
Disequilibria between ~(210)Po and ~(210)Pb in surface waters of the southern South China Sea and their implications 总被引：1，自引：0，他引：1
YANG Weifeng HUANG Yipu CHEN Min ZHANG Lei LI Hongbin LIU Guangshan QIU Yusheng 《中国科学D辑(英文版)》2006,49(1)
Naturally occurring 210Po (half-life 138.4d) is the granddaughter of 210Pb (half-life 22.3a), both are members of 238U decay series and have been inten-sively utilized to study kinetic aspects of material cy-cling in the ocean[1]. Based on radioactive disequilibria in the 226Ra-210Pb-210Po system, oceanographical processes with different timescales have been widely studied. Rama et al.[2] first detected excess 210Pb rela-tive to its precursor 226Ra in surface waters, and considered this exc… 相似文献
15.
Digital databases on 444 stations were used to carry out statistical analysis of regularities in the spatial distribution of Barents Sea water pollution. The analysis was focused on the concentrations in water of heavy metals (Cd, Cr, Cu, Hg, Ni, Pb, and Zn) and toxic organic compounds: hexachlorocyclohexanes, hexachlorobenzene, chlordans, DDT, polychlorbiphenyls, polycyclic aromatic hydrocarbons, and normal paraffins. The statistical analysis of data on pollutants was carried out along two major directions in their distribution: the vertical—in the surface and bottom water layers; and the horizontal—over water masses. Reliable differences were identified in the pollution level of different water masses of the Barents Sea. The frontal zone was found to concentrate pollution. 相似文献
16.
Seals are high trophic level feeders that bioaccumulate many contaminants to a greater degree than most lower trophic level organisms. Their trophic status in the marine food web and wide-spread distribution make seals useful sentinels of arctic environmental change. The purpose of this investigation is to document the levels and bioaccumulation potential of radiocaesium in high latitude seal species for which data have not previously been available. The study was carried out on harp, ringed, and bearded seals caught north of the island archipelago of Svalbard (82°N) in 1999. The results are then compared with previous studies in order to elucidate factors responsible for bioaccumulation in Arctic seals. Concentrations of 137Cs were determined in muscle, liver and kidney samples from a total of 10 juvenile and one adult seal. The mean concentration in muscle samples for all animals was 0.23±0.045 Bq/kg f.w. 137Cs concentrations in both liver and kidney samples were near detection limits (≈0.2 Bq/kg f.w.). The results are consistent with previous studies indicating low levels of radiocaesium in Arctic seals in response to a long term trend of decreasing levels of 137Cs in the Barents Sea region. Bioconcentration factors (BCFs) estimated for seals from NE Svalbard are low, ranging from 34 to 130. Comparing these values with reported BCFs for Greenland seals from other sectors of the European Arctic, we suggest that the combination of physiological and ecological factors on radiocaesium bioaccumulation is comparable among different Arctic seal populations. The application of this work to Arctic monitoring and assessment programs is discussed. 相似文献
17.
Benthic communities as influenced by nuclear testing and radioactive waste disposal off Novaya Zemlya in the Russian Arctic 总被引：1，自引：0，他引：1
V. B. Pogrebov S. I. Fokin V. V. Galtsova G. I. Ivanov 《Marine pollution bulletin》1997,35(7-12):333-339
On the material of sampling, accomplished in: (i) Chernaya Inlet of the Barents Sea (one of the flats of Novaya Zemlya Nuclear Test Site), (ii) in the Open Kara Sea and (iii) on the shoal off Novaya Zemlya from Stepovogo Fjord to Abrosimov Fjord (sites of radioactive waste disposal with activity 90% from total for the Kara Sea), characteristics of macro-, meio- and microbenthic bottom communities on the areas of potential radioactive danger are presented. Significant changes in macro- and meiobenthic communities are not revealed. In Chernaya Inlet, where three nuclear explosions were held in 1955–1961, disturbances in microbenthic protozoa communities are found. These disturbances expressed in the infusoria elimination from the fauna of the inlet deep-water sites and in morphological abnormality of this group individuals in population, inhabiting low depth of the inlet top. The assumed origin of revealed disturbances is high concentration (by 3–4 orders of magnitude above the background) of plutonium in bottom sediments of the inlet. Similar responses of the microbenthic flagellates are not detected. 相似文献
18.
Sea‐bed diffractions are frequently observed for several of the fields in the Norwegian Sea and the Barents Sea. This is a challenge in time lapse seismic analysis, since diffracted multiples are difficult to remove by processing and therefore is a major source of poor time lapse data quality. In this work we test if the diffractions can be used for enhanced 4D interpretation. By analysing the time‐shift of the sea‐bed diffraction hyperbola between the base and monitor it is tested if changes in water velocity and tides can be estimated. Two models using time lapse diffraction analysis are tested: the first one simply adds time‐shifts for the two branches of the diffraction hyperbola and this average time‐shift is then used to estimate the water velocity change. The other method uses an inversion method based on the diffraction equation for a point diffractor to estimate the velocity change. In‐line common‐midpoint shifts are estimated by subtracting the time‐shifts of both hyperbola branches followed by direct inversion. The diffraction based time‐shifts are compared to time‐shifts estimated by standard cross‐correlation of the sea‐bed reflection. The averaging method gives slightly higher uncertainties, while the inversion using an exact traveltime equation gives similar uncertainties compared to the sea‐bed reflection method. 相似文献
19.
Free-Air Anomalies (FAA) for the Norwegian marine area including some parts of the North Sea, the Norwegian Sea and the Barents
Sea are computed from satellite altimetry data. A total of 84 cycles of ERS2 along-track data, 25 cycles of ENVISAT along-track
data and high density ERS1 data during its geodetic mission are used. The new geopotential model from the Gravity Recovery
and Climate Experiment (GRACE) mission, GGM02S (Tapely et al., 2005) is used to compute the long wavelength contributions
of the geoid and the FAA. To correct data for mean dynamic topography, the available Levitus climatology model (Levitus and
Boyer, 1994) is used. Corrected data are then used to compute along-track gradients in each cycle-pass to suppress the orbital
and the atmospheric errors below the noise level of the altimeter. Resulted gradients are then stacked and the east-west and
the north-south components of the deflection of verticals are computed where ascending and descending tracks meet each other.
Finally, the inverse Vening-Meinesz formula is implemented on the gridded deflections to compute FAA. Results are then compared
with available marine and airborne data. Standard deviations of ± 4.301 and ± 6.159 mGal in comparison with airborne and marine
FAA were achieved. Thereafter, the derived anomalies are combined with marine and airborne FAA together with the land FAA
to compute a fine resolution geoid for Norway and the surrounding marine areas. This geoid is evaluated over sea and land
with the synthetic geoid (the geoid derived from the mean sea surface by subtracting the mean dynamic topography) and Global
Positioning System (GPS)-levelling and the standard deviations of the differences are ± 20.9 and ± 12.8 cm respectively.
ali.soltanpour@ntnu.no, hossein.nahavandchi@ntnu.no, kourosh.ghazavi@ntnu.no 相似文献
20.
The chemical speciation of dissolved copper was investigated in waters from the limno-corrals of the MELIMEX project and compared
with speciation data from other Swiss lakes. Copper is complexed primarily by organic ligands having molecular sizes between
104 and 103 daltons. The mean concentration of the ligands is approximately 5×10−7 mole/mg DOC. The conditional stability constants (pH=8.8) are about 1011. An increased metal load did not induce an increase of binding ligands. A comparison of calculated Cu2+ concentration with corresponding copper contents in the biomass leads to the conclusion that organic ligands and pH are the
most important factors in deciding the biological availability of copper. However the sorption capacity of the biomass depends
as well on the variety of plankton species. 相似文献