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Wyświetlanie 1-15 z 18
Tytuł:
Relationships between water temperature, nutrients and dissolved oxygen in the Northern Gulf of Aqaba, Red Sea
Autorzy:
Manasrah, R.
Raheed, M.
Badran, M.I.
Powiązania:
https://bibliotekanauki.pl/articles/49092.pdf
Data publikacji:
2006
Wydawca:
Polska Akademia Nauk. Instytut Oceanologii PAN
Tematy:
stratification
nutrient
Aqaba Gulf
temperature
sea water
Red Sea
oxygen
Opis:
Five years (1998, 2000–2003) of summer records of temperature, nutrients and dissolved oxygen concentrations in the upper 400 m of the water column of the northern Gulf of Aqaba were employed to produce a simple statistical model of the relationship between temperature versus nitrate, phosphate, silicate andd issolved oxygen concentrations. Temperature profiles in the upper 400 m during summer revealeda clear thermocline in the upper 200 m. This was reflected in nutrient ando xygen concentrations as nitrate, phosphate, and silicate increasedfr om the surface to deep water while dissolved oxygen decreased. The best fit relationship between temperature versus nitrate andphosphate was inverse linear and the best fit correlation between temperature versus silicate andd issolvedo xygen was fractional. The observedn utrient concentrations were shaped by a combination of the hydrodynamics and biological factors. Deep winter mixing and high nutrient concentrations dominate during winter. Shortly after the water stratifies in spring, the nutrients are drawn down by phytoplankton during the spring bloom and remain low throughout the rest of the year. The regression equations presented here will be useful in estimating nutrient concentrations from temperature records as long as the annual natural cycle is the main driver of nutrient concentrations and external inputs are insignificant. Deviations from these relationships in the future could provide insight into modifications in the nutrient concentrations probably resulting from new nutrient sources, such as anthropogenic inputs.
Źródło:
Oceanologia; 2006, 48, 2
0078-3234
Pojawia się w:
Oceanologia
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Variability of currents over the southern slope of the Gulf of Finland
Autorzy:
Suhhova, I.
Pavelson, J.
Lagemaa, P.
Powiązania:
https://bibliotekanauki.pl/articles/48946.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Instytut Oceanologii PAN
Tematy:
stratification
upwelling
downwelling
Finland Gulf
coastal sea water
seasonal thermocline
current velocity
Źródło:
Oceanologia; 2015, 57, 2
0078-3234
Pojawia się w:
Oceanologia
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On the buoyant sub-surface salinity maxima in the Gulf of Riga
Autorzy:
Liblik, T.
Skudra, M.
Lips, U.
Powiązania:
https://bibliotekanauki.pl/articles/48990.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Instytut Oceanologii PAN
Tematy:
thermohaline structure
Riga Gulf
water column
temperature
salinity
stratification
water exchange
intrusion
Opis:
Thermohaline structure in the Gulf of Riga (GoR) was investigated by a multiplatform measurement campaign in summer 2015. Stratification of the water column was mainly controlled by the temperature while salinity had only a minor contribution. Buoyant salinity maxima with variable strength were observed in the intermediate layer of the Gulf of Riga. The salinity maxima were likely formed by a simultaneous upwelling—downwelling event at the two opposite sides of the Irbe strait. The inflowing salty water did not reach the deeper (> 35 m) parts of the gulf and, therefore, the near-bottom layer of the gulf remained isolated throughout the summer. Thus, the lateral water exchange regime in the near bottom layer of the Gulf of Riga is more complicated than it was thought previously. We suggest that the occurrence of this type of water exchange resulting in a buoyant inflow and lack of lateral transport into the near-bottom layers might contribute to the rapid seasonal oxygen decline in the Gulf of Riga
Źródło:
Oceanologia; 2017, 59, 2
0078-3234
Pojawia się w:
Oceanologia
Dostawca treści:
Biblioteka Nauki
Artykuł
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:
Nutrient flux fuels the summer primary productivity in the oligotrophic waters of the Gulf of Aqaba, Red Sea
Autorzy:
Badran, M.I.
Rasheed, M.
Manasrah, R.
Al-Najjar, T.
Powiązania:
https://bibliotekanauki.pl/articles/47744.pdf
Data publikacji:
2005
Wydawca:
Polska Akademia Nauk. Instytut Oceanologii PAN
Tematy:
Aqaba Gulf
biological stress
diffusion model
chlorophyll a
oligotrophic water
primary productivity
thermohaline stratification
nutrient flux
Red Sea
Opis:
The thermohaline characteristics of the Gulf of Aqaba, Red Sea, depict a welldefined seasonal pattern of winter mixing from December to April and summer stratification from May to November. This thermohaline structure is a major controlling factor of the nutrient, chlorophyll a and primary productivity seasonal cycles. The nitrate and chlorophyll a concentration records generated down to 200 m at a vertical resolution of 25 m – weekly during 1994, 1995 and every two weeks from April 1997 through to December 2000 – are employed to assess the nitrogen flux across the summer thermocline of the Gulf of Aqaba. The flux calculations are based on a simple diffusion model that incorporates the physical stress eddy diffusivity factor Kz and a biological stress factor k. Both Kz and k are calculated using the Michaelis-Menten equation and the nitrate concentration gradient. The total nitrate flux of the Gulf of Aqaba during the seven summer months (May–November) is estimated at 0.52 moleN m−2. In relation to established primary productivity values (75.5 gC m−2 (May November)−1) and the generated chlorophyll a records, this yields an f fraction of new to total primary production of 0.50. This relatively high f value is discussed with respect to the geophysical characteristics of the Gulf of Aqaba and similar oceanic basins. The remaining 50% is accounted for by cross-sectional flow from the relatively nutrientrich coral reef coastal habitat and rapid recycling, triggered by high irradiance and water temperature.
Źródło:
Oceanologia; 2005, 47, 1
0078-3234
Pojawia się w:
Oceanologia
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Water column conditions in a coastal lagoon near Jeddah, Red Sea
Autorzy:
Albarakati, A.M.A.
Ahmad, F.
Powiązania:
https://bibliotekanauki.pl/articles/48751.pdf
Data publikacji:
2012
Wydawca:
Polska Akademia Nauk. Instytut Oceanologii PAN
Tematy:
water column
coastal lagoon
Red Sea
heat balance
air-sea interface
stratification
wind stress
heat flux
bottom topography
Źródło:
Oceanologia; 2012, 54, 4
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:
Influence of density stratification on effluent plume dynamics
Autorzy:
Loncar, G.
Paklar, G.B.
Janekovic, I.
Powiązania:
https://bibliotekanauki.pl/articles/47653.pdf
Data publikacji:
2011
Wydawca:
Polska Akademia Nauk. Instytut Oceanologii PAN
Tematy:
3D numerical model
Croatia
density stratification
numerical model
numerical simulation
Rijeka Bay
salinity
sea temperature
statistical analysis
submarine outfall
submarine sewage
Opis:
In this study we modelled sea temperature (T ), salinity (S) and density field dynamics using a 3D numerical model applied to Rijeka Bay (Croatia) in order to explore their effect on effluent plume dynamics in the vicinity of four submarine sewage outfalls when the bora wind (NE direction) is blowing. The vertical density stratification in the area studied is strongly related to the bora wind, which contributes significantly to the lowering of the pycnocline depth through enhanced mixing in the vertical, giving rise to changes in the neutral buoyancy level. The features of near-field plume dynamics were calculated with the use of a separate near-field numerical model, using information on the vertical density distribution previously calculated using a 3D numerical model. The results of the numerical simulations and statistical analysis of the wind data indicate a very low probability of complete water column homogenization and consequent effluent plume rise to the sea surface under the influence of the bora wind during the peak tourist season (May–September).
Źródło:
Oceanologia; 2011, 53, 2
0078-3234
Pojawia się w:
Oceanologia
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Potential risk of Mesodinium rubrum bloom in the aquaculture area of Dapeng’ao cove, China: diurnal changes in the ciliate community structure in the surface water
Autorzy:
Liu, H.
Song, X.
Huang, L.
Tan, Y.
Zhong, Y.
Huang, J.R.
Powiązania:
https://bibliotekanauki.pl/articles/47949.pdf
Data publikacji:
2012
Wydawca:
Polska Akademia Nauk. Instytut Oceanologii PAN
Tematy:
potential risk
Mesodinium rubrum
bloom
aquaculture area
Dapeng'ao cove
China
diurnal change
ciliate community
surface water
heavy rainfall
water column
stratification
irradiance
Opis:
Diurnal changes in the structure of the ciliate community in surface waters were studied in the aquaculture area of Dapeng’ao cove, China. Two periods of heavy rainfall occurred during the study period, intensifying water column stratification and influencing the water’s properties. A total of 21 ciliate taxa from 15 genera were identified; the dominant species was Mesodinium rubrum. The maximum abundance of M. rubrum reached 3.92×104 indiv. dm−3, contributing 95.1% (mean value) to the total ciliate abundance. Diurnal changes in M. rubrum abundance were highly variable, the driving force probably being irradiance and food availability. The results suggest that M. rubrum may form blooms in aquaculture areas when there is a suitable physical regime with enriched nutrients, which is potentially harmful to the fish-farming industry.
Źródło:
Oceanologia; 2012, 54, 1
0078-3234
Pojawia się w:
Oceanologia
Dostawca treści:
Biblioteka Nauki
Artykuł
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