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Wyświetlanie 1-11 z 11
Tytuł:
Winter upwelling in the Gulf of Finland, Baltic Sea
Autorzy:
Suursaar, U.
Powiązania:
https://bibliotekanauki.pl/articles/2078916.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Instytut Oceanologii PAN
Tematy:
upwelling
winter
nearshore region
Finland Gulf
Baltic Sea
stratification
vertical flux
water temperature
Opis:
Traditionally, upwelling-related studies in the Baltic Sea have been limited to the period from May to September. Based on wintertime in situ measurements at two nearshore locations in the Gulf of Finland, clear evidence of winter “warm” upwelling events was detected and analysed. The process was very common. At a 10 m deep location, upwelling caused water temperature (T) to switch from 0—1 to 4—5°C and salinity (S) to switch from 4.5 to 6 PSU; at 20 m depth it caused a switch in T between 1 and 2—4°C and in S between 5.5 and 6.8 PSU. Differently from summer upwelling, T and S variations were positively correlated to each other. Salinity variations remained roughly the same throughout the winter, whereas T differences were higher in winter onset, then decreased to ca. 1°C, and increased again after the process reversed to summer-type upwelling in April—May. Based on analysis of SatBaltyk (January to March) sea surface temperature and salinity product imagery, winter upwelling occurrence along the North Estonian coast was 21—28% over 2010—2021, and slightly less along the Finnish coast. Regarding S variations, winter upwelling occurred with roughly similar frequencies and impacts in the northern and southern parts of the gulf. However, the impacts on T and sea ice conditions were highly asymmetrical. Upwelling kept the Estonian coast ice-free longer and water temperatures slightly higher than at the Finnish coast. Winter upwelling as a phenomenon has long been ignored and therefore probably underestimated.
Źródło:
Oceanologia; 2021, 63, 3; 359-369
0078-3234
Pojawia się w:
Oceanologia
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Correlation analyses of Baltic Sea winter water mass formation and its impact on secondary and tertiary production
Autorzy:
Hinrichsen, H.H.
Lehmann, A.
Petereit, C.
Schmidt, J.
Powiązania:
https://bibliotekanauki.pl/articles/47630.pdf
Data publikacji:
2007
Wydawca:
Polska Akademia Nauk. Instytut Oceanologii PAN
Tematy:
zooplankton
fish egg
development
thermal stratification
winter
water
Baltic Sea
mass formation
survival
Opis:
The thermal stratification of the upper water layers in the Baltic Sea varies seasonally in response to the annual cycle of solar heating and wind-induced mixing. In winter,the stratification down to the halocline is almost completely eroded by convection and strong wind mixing. Monthly averaged temperature profiles obtained from the ICES hydrographic database were used to study the long-term variability (1950 to 2005) of winter water mass formation in different deep basins of the Baltic Sea east of the island of Bornholm. Besides strong interannual variability of deep winter water temperatures,the last two decades show a positive trend (increase of 1–1.5◦C). Correlations of winter surface temperatures to temperatures of the winter water body located directly above or within the top of the halocline were strongly positive until the autumn months. Such a close coupling allows sea surface temperatures in winter to be used to forecast the seasonal development of the thermal signature in deeper layers with a high degree of confidence. The most significant impact of winter sea surface temperatures on the thermal signature in this depth range can be assigned to February/March. Stronger solar heating during spring and summer results in thermal stratification of the water column leading to a complete decoupling of surface and deep winter water temperatures. Based on laboratory experiments,temp erature-dependent relationships were utilised to analyse interannual variations of biological processes with special emphasis on the upper trophic levels (e.g.,stage-sp ecific developmental rates of zooplankton and survival rates of fish eggs).
Źródło:
Oceanologia; 2007, 49, 3
0078-3234
Pojawia się w:
Oceanologia
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Processes and factors influencing the through-flow of new deepwater in the Bornholm Basin
Autorzy:
Stigebrandt, A.
Powiązania:
https://bibliotekanauki.pl/articles/49102.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Instytut Oceanologii PAN
Tematy:
hydrographic condition
Bornholm Basin
salinity
oxygen concentration
vertical stratification
deep water
Baltic Sea
Opis:
This paper is based on the idea that the hydrographical conditions in the Bornholm Basin, and any other basin, can be understood from knowledge of general hydromechanical principles and basin-specific factors. Published results on the variability of the vertical stratification are shown and discussed. Such analyses demonstrate the residence time of water at different depth levels. Different modes of currents forced by winds and by stratification gradients at open vertical boundaries are presented. Vertical mixing is discussed and published results for the Bornholm Basin are shown. An experiment demonstrates that the diffusive properties of the enclosed basin, i.e. below the sill depth of the Słupsk Furrow, can be computed quite well from the horizontal mean vertical diffusivity obtained from historical hydrographical observations. A published two decades long simulation of the vertical stratification shows that the through flow and modification of new deepwater in the Bornholm Basin can be well described based on existing knowledge regarding crucial hydromechanical processes. It also suggests, indirectly, that there should be a weak anticyclonic circulation above the sill depth, which is supported by current measurements.
Źródło:
Oceanologia; 2017, 59, 1
0078-3234
Pojawia się w:
Oceanologia
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Stratification of particulate organic carbon and nitrogen in the Gdańsk Deep (Southern Baltic Sea)
Autorzy:
Burska, D.
Pryputniewicz, D.
Falkowska, L.
Powiązania:
https://bibliotekanauki.pl/articles/47610.pdf
Data publikacji:
2005
Wydawca:
Polska Akademia Nauk. Instytut Oceanologii PAN
Tematy:
stratification
Gdansk Deep
nitrogen
particulate organic carbon
carbon
particulate organic nitrogen
flux
Baltic Sea
Opis:
Particulate organic carbon (POC) and nitrogen (PON) concentrations and fluxes were measured during an experiment in the Gdańsk Deep in late spring (30.05. –06.06.2001). The vertical POC and PON concentration profiles were characterised by the highest values in the euphotic layer,a gradual decrease with depth, and an increase below the halocline. The hydrophysical conditions had a decisive impact on POC and PON fluxes in the water column. Preferential removal of nitrogen from suspended mater was observed in the entire water column (maximum – in the vicinity of thermocline). There were also differences in the diurnal effectiveness of nitrogen removal as compared to carbon removal. The removal rate was highest at night.
Źródło:
Oceanologia; 2005, 47, 2
0078-3234
Pojawia się w:
Oceanologia
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Diurnal variations in nitrogen, phosphorus and iron compounds in the Southern Baltic Sea
Autorzy:
Sikorowicz, G.
Falkowska, L.
Burska, D.
Dunajska, D.
Pryputniewicz, D.
Magulski, R.
Lewandowska, A.
Powiązania:
https://bibliotekanauki.pl/articles/47649.pdf
Data publikacji:
2005
Wydawca:
Polska Akademia Nauk. Instytut Oceanologii PAN
Tematy:
iron
nutrient
Gdansk Deep
nitrogen
density stratification
diurnal variation
Baltic Sea
oxygen condition
phosphorus
Opis:
In order to assess their short-term variability, nutrient concentrations were measured at standard depths at 2 h intervals in the deepest region of the Gdańsk Deep during the first ten days of June 2001. The mean concentrations of nutrients in the euphotic zone were: NN (NO2 −, NO3 −, NH4 +) – 1.93 μmol dm−3, PO4 3− – 0.12 μmol dm−3 and Fetot – 0.11 μmol dm−3. During daylight hours, when the rate of assimilation was fastest, concentrations of nitrogen, phosphorus and iron compounds were very low. The phosphate concentration fell to a minimum (0.03 μmol dm−3) between 04:00 and 10:00 hrs, while total iron dropped to 0.01 μmol dm−3 between 10:00 and 16:00 hrs. Both levels were below the limiting values for phosphorus and iron. At night, concentrations of NO3 − and PO4 3− rose by 25%, those of NH4 + and Fetot by 35%. The mean molar ratios of NN:PO4 3− and Fetot:PO4 3− in the surface layer were subject to significant daily fluctuations. The molar NN:PO4 3− ratio was higher than the optimum value established for the Baltic Sea. Below the halocline, the concentrations of dissolved iron and phosphorus rose as a result of diffusion from sediments in response to changing redox conditions.
Źródło:
Oceanologia; 2005, 47, 2
0078-3234
Pojawia się w:
Oceanologia
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Dynamic features of successive upwelling events in the Baltic Sea - a numerical case study
Autorzy:
Myrberg, K.
Andrejev, O.
Lehmann, A.
Powiązania:
https://bibliotekanauki.pl/articles/48404.pdf
Data publikacji:
2010
Wydawca:
Polska Akademia Nauk. Instytut Oceanologii PAN
Tematy:
Baltic Sea
Hel Peninsula
numerical modelling
coastal upwelling
thermal stratification
sea surface temperature
water column
Polish coast
Opis:
Coastal upwelling often reveals itself during the thermal stratification season as an abrupt sea surface temperature (SST) drop. Its intensity depends not only on the magnitude of an upwelling-favourable wind impulse but also on the temperature stratification of the water column during the initial stage of the event. When a ‘chain’ of upwelling events is taking place, one event may play a part in forming the initial stratification for the next one; consequently, SST may drop significantly even with a reduced wind impulse. Two upwelling events were simulated on the Polish coast in August 1996 using a three-dimensional, baroclinic prognostic model. The model results proved to be in good agreement with in situ observations and satellite data. Comparison of the simulated upwelling events show that the first one required a wind impulse of 28 000 kg m−1 s−1 to reach its mature, full form, whereas an impulse of only 7500 kg m−1 s−1 was sufficient to bring about a significant drop in SST at the end of the second event. In practical applications like operational modelling, the initial stratification conditions prior to an upwelling event should be described with care in order to be able to simulate the coming event with very good accuracy.
Źródło:
Oceanologia; 2010, 52, 1; 77-99
0078-3234
Pojawia się w:
Oceanologia
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Characteristics and inter-annual changes in temperature, salinity and density distribution in the Gulf of Riga
Autorzy:
Skudra, M.
Lips, U.
Powiązania:
https://bibliotekanauki.pl/articles/48540.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Instytut Oceanologii PAN
Tematy:
Riga Gulf
interannual variability
long-term change
temperature
salinity
density
Baltic Sea
vertical stratification
internal Rossby radius
Opis:
Available CTD profiles from the Gulf of Riga (May—August, 1993—2012) were analyzed to study inter-annual and long-term changes in temperature, salinity and density in relation to river runoff and atmospheric forcing (e.g. Baltic Sea Index). To describe temporal changes in vertical stratification, the upper mixed layer (UML) and deep layer (DL) parameters were estimated. On average the UML depth increases from 8.7 m in May to 9.0, 11.5 and 13.7 m in June, July and August, respectively, and the UML temperature increases from 8.08C to 12.5, 18.7 and 18.68C (May, June, July and August) while the UML salinity increases from 4.90 g kg1 to 5.14, 5.28 and 5.38 g kg1, respectively. High correlation (r = 0.82) was found between the inter-annual changes in river runoff (spring) and mean salinity in the UML in August as well as between DL mean salinity (r = 0.88) and density (r = 0.84) in the Irbe Strait and DL mean salinity and density in the Gulf of Riga. Inter-annual changes in the UML depth as well as in DL salinity and density had a significant correlation with the changes in Baltic Sea Index. The strongest stratification (August) can be observed in the years with the highest UML temperature and the highest river run-off in spring. We suggest that the predicted increase in water temperature and changes in river run-off due to the climate change would result in faster development of the seasonal thermocline in spring and stronger vertical stratification in summer.
Źródło:
Oceanologia; 2017, 59, 1
0078-3234
Pojawia się w:
Oceanologia
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On the possibility of convective overturning in the Slupsk Furrow overflow of the Baltic Sea
Autorzy:
Zhurbas, V.
Elken, J.
Paka, V.
Piechura, J.
Chubarenko, I.
Vali, G.
Golenko, N.
Shchuka, S.
Powiązania:
https://bibliotekanauki.pl/articles/48298.pdf
Data publikacji:
2011
Wydawca:
Polska Akademia Nauk. Instytut Oceanologii PAN
Tematy:
Baltic Sea
deep water
dense water
density stratification
gravity current
numerical simulation
saline water
Slupsk Furrow
transverse circulation
water mass
Opis:
Closely spaced CTD transects across the Słupsk Furrow displayed a ‘downward- bending’ of salinity contours below the salinity interface on the southern flank due to a transverse circulation in the saline water overflow. Numerical simulation of a gravity current in an idealized channel with geometry, dimensions and initial density stratification all much the same as in the Słupsk Furrow was applied to verify whether the downward-bending could be transformed into an inverted density stratification. Some arguments in favour of the possibility of convective overturning due to the differential transverse advection beneath the gravity current, brought on by the numerical simulations, are discussed.
Źródło:
Oceanologia; 2011, 53, 3
0078-3234
Pojawia się w:
Oceanologia
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Solar radiation in the Baltic Sea
Autorzy:
Dera, J.
Wozniak, B.
Powiązania:
https://bibliotekanauki.pl/articles/48691.pdf
Data publikacji:
2010
Wydawca:
Polska Akademia Nauk. Instytut Oceanologii PAN
Tematy:
Baltic Sea
chlorophyll a
eutrophic area
evaporation
marine environment
natural irradiance
photochemical process
photosynthesis
short-term fluctuation
solar radiation
stratification
underwater irradiance
vertical distribution
Opis:
The influx of solar radiation to the Baltic Sea and its penetration into its waters is described on the basis of selected results of optical and bio-optical studies in the Baltic published by various authors during the past ca 50 years. The variability in the natural irradiance of this sea is illustrated on time scales from short-term fluctuations occurring during a single day to differences in mean monthly values over a period of many years. Data on variability of the proportions between UV, VIS and IR energy in the light reaching the sea surface are also discussed. Long-term monthly mean values of the incident solar radiation flux at the surface of the Baltic Proper are given; they were obtained from meteorological and solar radiation measurements and model approximations. The transmittances of these mean monthly radiation fluxes across the surface of the Baltic are given, as are the typical energy and spectral characteristics of the underwater irradiance, its attenuation with depth in the sea and the associated euphotic zone depths, as well as typical ranges of variability of these characteristics in different Baltic basins. Some of these characteristics are illustrated by typical empirical data. These mean values are not fully representative, however, because with the sole use of classical in situ measurement methods from on board research vessels in the Baltic, it has not been possible to gather a sufficiently representative set of empirical data that would adequately reflect the variability of the optical haracteristics of all the basins of this sea. The article goes on to introduce the statistical model of vertical distributions of chlorophyll a concentration in the Baltic and the bio-otical model of Baltic Case 2 waters, the use of which contribute very significantly to this description of the optical characteristics and will enable this data set to be hugely expanded to include all the Baltic basins. This opportunity is presented by the optical parameterization of Baltic Case 2 waters, i.e. by the mathematical formulas of the model linking the coefficient of attenuation of downward irradiance with the surface chlorophyll a concentration, as well as the method developed for the efficient and systematic satellite remote sensing of the chlorophyll a concentration over the entire Baltic Sea area.
Źródło:
Oceanologia; 2010, 52, 4
0078-3234
Pojawia się w:
Oceanologia
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Baroclinic Rossby radius of deformation in the Southern Baltic Sea
Autorzy:
Osinski, R.
Rak, D.
Walczowski, W.
Piechura, J.
Powiązania:
https://bibliotekanauki.pl/articles/47732.pdf
Data publikacji:
2010
Wydawca:
Polska Akademia Nauk. Instytut Oceanologii PAN
Tematy:
baroclinic Rossby radius
deformation
Baltic Sea
mesoscale dynamics
fundamental horizontal scale
mesoscale process
Bornholm Basin
Slupsk Furrow
Gdansk Basin
seasonal variability
saline water
vertical stratification
Opis:
The first baroclinic Rossby radius of deformation (R1) is a fundamental horizontal scale of mesoscale processes. This scale is important for planning both numerical modelling and study areas. R1 was computed on the basis of an 11-year series of high resolution CTD measurements collected during r/v ‘Oceania’ cruises. The data set covered the three main basins of the Baltic Proper: the Bornholm Basin (BB), the Słupsk Furrow (SF) and the Gdańsk Basin (GB). The smallest mean value of R1 was found in the Gdańsk Basin (5.2 km), the largest one in the Bornholm Deep (7.3 km). The seasonal variability of R1 is lower in the western basin than in the eastern one. The seasonal cycle of R1 may be broken by extreme events, e.g. main Baltic inflows (MBI) of saline water. The inflowing water rebuilds the vertical stratification in the southern Baltic Sea and dramatically changes the R1 values. The difference of R1 between a stagnation period and an inflow situation is shown on the basis of observations made during 2002–2003. The main inflow occurred in winter, after ten years of stagnation, and the very low values of R1 (about 4 km) changed to very high ones (more than 9 km). Analysis of stagnation and saltwater inflow events may throw light on the value of R1 in future climatic scenarios. The potential influence of climate change on Baltic Sea salinity, especially a decrease in MBI activity, may change the baroclinic Rossby radius of deformation and the mesoscale dynamics. Values of R1 are expected to be lower in the future climate than those measured nowadays.
Źródło:
Oceanologia; 2010, 52, 3; 417-429
0078-3234
Pojawia się w:
Oceanologia
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Computation of energy for diapycnal mixing in the Baltic Sea due to internal wave drag acting on wind-driven barotropic currents
Autorzy:
Nohr, C.
Gustafsson, B.G.
Powiązania:
https://bibliotekanauki.pl/articles/48609.pdf
Data publikacji:
2009
Wydawca:
Polska Akademia Nauk. Instytut Oceanologii PAN
Tematy:
Baltic Sea
North Sea
barotropic motion
computation
deep water
halocline
internal wave
saline water
sea level
seasonal thermocline
shallow water
stratification
surface area
turbulent mixing
water exchange
wind force
Opis:
The pathways of energy supply for mixing the deep waters of the Baltic Sea is largely unknown. In this paper, a parameterization of the internal wave drag forces on barotropic motion is developed and implemented into a two-dimensional shallow water model of the Baltic Sea. The model is validated against observed sea levels. The dissipation of barotropic motion by internal wave drag that is quantified from the model results show that breaking internal waves generated by wind forced barotropic motions can contribute significantly to diapycnal mixing in the deep water of the Baltic Sea.
Źródło:
Oceanologia; 2009, 51, 4
0078-3234
Pojawia się w:
Oceanologia
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-11 z 11

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