Oceanologia No. 62 (4PA / 20)


Original research article


Original research article

Observations on relations between marine aerosol fluxes and surface-generated noise in the southern Baltic Sea
Oceanologia 2020, 62(4PA), 413-427

Piotr Markuszewski1,*, Zygmunt Klusek2, Ernst D. Nilsson3, Tomasz Petelski1
1Physical Oceanography Department, Institute of Oceanology, Polish Academy of Sciences, Sopot, Poland;
e-mail: pmarkusz@iopan.pl
2Marine Physics Department, Institute of Oceanology, Polish Academy of Sciences, Sopot, Poland
3Department of Environmental Science and Analytical Chemistry, Stockholm University, Stockholm, Sweden
*corresponding author

keywords: Sea spray fluxes, Underwater ambient bubbles noise, Baltic Sea

Received 8 January 2020, Revised 5 May 2020, Accepted 7 May 2020, Available online 22 May 2020.


This study presents the preliminary results of combining underwater acoustic ambient noise measurements with those of in-situ sea spray fluxes (SSF). Hydroacoustic measurements (in the frequency range 80 Hz –12.5 kHz) were made using an underwater noise recording system developed at the Institute of Oceanology of the Polish Academy of Sciences which was then deployed in the southern Baltic Sea. The simultaneous measurements of coarse sea spray fluxes (with particle diameters ranging from 0.5 to 47 µm) were made on board the r/v Oceania using the gradient method. Observations were conducted for the duration of the passage of an atmospheric front that lasted 2.5 days (60 hours of measurements). There were significant differences in the sound pressure level (SPL) and aerosol fluxes observed between the first part of measurements (developing wave state) and the second part (developed waves). Wave parameters, such as peak period, significant wave height, wave age, and mean wave slope acquired from the WAM (WAve Model), were used to investigate the impact of wave field properties on noise and aerosol flux measurements. We observed different behaviours in the power spectrum density (PSD) levels of noise for these parameters depending on the wave state development.
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Study of ice cover impact on hydrodynamic processes in the Curonian Lagoon through numerical modeling
Oceanologia 2020, 62(4PA), 428-442

Rasa Idzelytė1,*, Jovita Mėžinė1, Petras Zemlys1, Georg Umgiesser2,1
1Marine Research Institute, Klaipėda University, Klaipėda, Lithuania;
e-mail: rasa.idzelyte@apc.ku.lt
2CNR — National Research Council of Italy, ISMAR — Institute of Marine Sciences, Venice, Italy
*corresponding author

keywords: Ice cover impact, Water circulation, Numerical modelling, SHYFEM, Curonian Lagoon

Received 27 October 2019, Revised 22 April 2020, Accepted 23 April 2020, Available online 18 May 2020.


In this study, we present an analysis of the hydrodynamic processes under ice cover in the largest lagoon in Europe – the Curonian Lagoon. By applying a finite element numerical modelling system (SHYFEM) and remote sensing ice cover data, the residual circulation, water fluxes through specific areas of the lagoon, saltwater intrusions, and water residence time (WRT) were investigated. The results, taken over an 11 year period, show that ice cover affects the circulation patterns in the lagoon by forming and shifting different gyre systems. Different circulation patterns are observed throughout all the meteorological seasons of the year. Since ice decreases circulation, water fluxes also decrease, especially in a cross-section in the middle of the lagoon, where the ice-cover suppressed wind-stress has a higher impact on the water movement rather than it has in the north. The presence of ice cover also decreases the salinity of the water in the northern part of the lagoon. In general, the salinity in the water column averaged over different periods is vertically uniform, however, a slight increase of salt concentration can be observed at the bottom layers in the Klaipėda Strait, where the difference of >1 PSU between bottom and top layers shows up on average 130 hours per year. The ice cover also decreases the saltwater intrusions into the lagoon by nearly 14 days per year. The increase of WRT is most prominent after long ice cover periods, away from the river inlets, especially in the southern part of the lagoon, where without the help of the wind action, water takes a longer time to renew than in the northern part.
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Tidal characteristics in the Gulf of Khambhat, northern Arabian Sea – based on observation and global tidal model data
Oceanologia 2020, 62(4PA), 443-459

Aditi Mitra1,2, V. Sanil Kumar1,*, Basanta K. Jena3
1Ocean Engineering, CSIR-National Institute of Oceanography (Council of Scientific and Industrial Research), Dona Paula, Goa, India;
e-mail: sanil@nio.org
2Research Scholar, Bharathidasan University, Tiruchirappalli,Tamil Nadu, India
3Coastal and Environmental Engineering Division, National Institute of Ocean Technology, Pallikaranai, Chennai, India
*corresponding author

keywords: Gulf of Khambhat, Semi-enclosed basins, Tidal constituents, Tidal propagation, Sea-level

Received 4 September 2019, Revised 23 May 2020, Accepted 28 May 2020, Available online 7 June 2020.


Tidal characteristics of the Gulf of Khambhat are described based on measured and modelled sea-level data. Data were recorded at three locations inside and two locations outside the Gulf with record lengths of 6–12 months to study the tidal propagation. A northward increase in tidal amplitude is noticed from Daman (eastern side) and Diu (western side) and attains maxima at Bhavnagar. A similar trend is followed by the amplitude of the major tidal constituents, although there are discrepancies for that of the minor constituents. The non-tidal factor which influences the sea-level is the local wind, especially the alongshore component of wind. A positive correlation is obtained between the sea-level and the meridional component of wind at each location. Harmonic analysis of sea-level data shows that M2 is the major tidal constituent which propagates in a non-linear fashion inside the Gulf. Tides from two global tide models (MIKE21 and FES2014) have been compared with the measured data, which could be used for further prediction of the tides and sediment transport in the Gulf. The tide elevation derived from the MIKE21 model has further been used for the harmonic analysis of tide. The tides predicted using one-month data are up to 10% smaller than those predicted using the one-year data. The global tide model FES2014 data performs well with measured data for offshore locations, whereas it fails to predict the same for the inner Gulf locations. The study manifests the fact that to understand the dynamics of complex tidal areas, regional models should better be used than global tidal models.
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Physical oceanographic conditions and a sensitivity study on meltwater runoff in a West Greenland fjord: Kangerlussuaq
Oceanologia 2020, 62(4PA), 460-477

Dennis Monteban1,*, Jens Olaf Pepke Pedersen1, Morten Holtegaard Nielsen3
1DTU Space, Technical University of Denmark, Lyngby, Denmark;
e-mail: dmont@space.dtu.dk
2Norwegian University of Science and Technology, Trondheim, Norway
3Marine Science & Consulting ApS, Copenhagen, Denmark
*corresponding author

keywords: Arctic fjord, Hydrodynamic model, MIKE 3, Water masses, Meltwater runoff, Kangerlussuaq fjord

Received 28 November 2019, Revised 24 June 2020, Accepted 29 June 2020, Available online 11 July 2020.


In this paper, we discuss the first setup of a hydrodynamic model for the fjord-type estuary Kangerlussuaq, located in West Greenland. Having such a high-fidelity numerical model is important because it allows us to fill in the temporal and spatial gaps left by in situ data and it allows us to examine the response of the fjord to changes in ice sheet runoff. The numerical model is calibrated against in situ data, and a one-year simulation was performed to study the seasonal variability in the physical oceanographic environment and the fjord's response to changing meltwater runoff. The fjord consists of two distinct parts: a deep inner part that is 80 km long with weak currents and a shallow part that covers the outer 100 km of the fjord connected to the ocean. The outer part has very fast currents (∼1.3 m/s), which we suggest prevents winter sea ice formation. The dominant currents in the fjord are oriented parallel to the long axis of the fjord and are driven by tides and (during summer) freshwater inflow from meltwater-fed rivers. Furthermore, mixing processes are characterized by strong tidal mixing and bathymetric restrictions, and the deep-lying water mass is subject to renewal primarily in wintertime and is almost dynamically decoupled from the open ocean during summertime. Finally, a sensitivity study on the changing meltwater runoff was performed, showing that increasing freshwater runoff considerably strengthens stratification in the upper 100 m of the water column in the inner part of the fjord.
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Argo floats in the southern Baltic Sea
Oceanologia 2020, 62(4PA), 478-488

Waldemar Walczowski*, Małgorzata Merchel, Daniel Rak, Piotr Wieczorek, Ilona Goszczko
Institute of Oceanology, Polish Academy of Sciences, Sopot, Poland;
e-mail: walczows@iopan.plm
*corresponding author

keywords: Argo floats, Baltic Sea, Dissolved oxygen, Inflows

Received 1 April 2020, Revised 23 July 2020, Accepted 25 July 2020, Available online 7 August 2020.


This work aims to familiarize the reader with issues related to modern oceanographic measurement techniques performed by Argo autonomous profiling floats. The opportunity for this is the three years of innovative activity on the part of Argo-Poland in the Baltic Sea. Based on the experience and results acquired by the Institute of Oceanology of the Polish Academy of Sciences (IO PAN), we can say that a revolution in the Baltic Sea monitoring is underway. During three years of activity, the floats launched by IO PAN provided more than 1600 CTD profiles, including 600 O2 profiles. Together with synoptic data from ships, data from moorings and surface buoys, the Argo float measurements are an important part of the southern Baltic monitoring system. Two Argo floats launched by IO PAN collected enough data to determine the dynamics of the oxygen content in various layers, the extent of hypoxic and anoxic zones, and to detect small baroclinic inflows to the Gotland and Gdańsk Deeps.
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The impact of Klaipėda Port entrance channel dredging on the dynamics of coastal zone, Lithuania
Oceanologia 2020, 62(4PA), 489-500

Gintautas Žilinskas*, Rasa Janušaitė*, Darius Jarmalavičius*, Donatas Pupienis*
Nature Research Centre, Institute of Geology and Geography, Vilnius, Lithuania;
e-mail: gintautas.zilinskas@gamtc.lt; rasa.janusaite@gamtc.lt; darius.jarmalavicius@gamtc.lt; donatas.pupienis@gamtc.lt
*corresponding author

keywords: Southern Baltic, Sediment transport, Port jetties, Entrance, channel dredging

Received 20 May 2020, Revised 30 July 2020, Accepted 3 August 2020, Available online 15 August 2020.


Dredging entrance channels to ports on open littoral drift seashores often causes major morphological changes to the shoreline. This study aims to assess the impact of dredging the Port of Klaipėda's entrance channel and the construction of the jetties on the coastal zone. Based on an analysis of cartographic material collected between 1835 and 2017, and on field data (bathymetric surveys and cross-shore profile levelling), changes to the coastal zone in the area nearest to the port were evaluated. The dominant longshore sediment transport on the Lithuanian nearshore runs from south to north. Thus, based on established patterns, intensive accretion could have been expected to take place on the southern side of the port jetties and erosion on their northern side. However, in the case of the Port of Klaipėda, in the area nearest to the port on the updrift side of the port jetties, where accretion would have been expected to take place, the nearshore depth increased throughout the 20th century (when the length and configuration of the jetties did not change). The shoreline shifted landward instead of moving further out to sea. The present study shows that the intensive dredging of the entrance channel caused nearshore and shore erosion on the updrift side of the port jetties, even while a sufficient sediment load was being transported by the longshore drift.
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Increases in the temperature and salinity of deep and intermediate waters in the West Spitsbergen Current region in 1997–2016
Oceanologia 2020, 62(4PA), 501-510

Małgorzata Merchel*, Waldemar Walczowski
Institute of Oceanology, Polish Academy of Sciences, Sopot, Poland;
e-mail: merchel@iopan.gda.pl
*corresponding author

keywords: Climate change, Ocean warming, Heat content, Deep water, Intermediate water, Nordic Seas

Received 20 February 2020, Revised 3 August 2020, Accepted 3 August 2020, Available online 13 August 2020.


This study investigated the temporal variability in the basic physical properties of deep and intermediate waters in the West Spitsbergen Current region at 76°30’N latitude from 1997 to 2016. Emphasis was placed on quantifying the changes in temperature and salinity and determining the potential drivers of these changes. Hydrographic data were obtained during annual summer cruises aboard the r/v Oceania in the Nordic Seas. The increase in the water temperature, which was especially strong in the western part of the investigated section, was associated with considerable changes in the water layers salinity. The temperature and salinity of the intermediate water increased much faster (0.021°C yr−1 and 0.0022 yr−1, respectively) than those of the deep water (0.009°C yr−1 and 0.0004 yr−1, respectively). The warming rate in the upper 2000 m was also higher than the mean warming rate of the global ocean. The source of the deep water temperature and salinity increases was the deep water inflow from the Arctic Ocean into the Greenland Sea. In contrast, the increase in these properties in the intermediate water was associated with the advection of warmer and more saline Atlantic Water from the North Atlantic to the Nordic Seas.
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Combined impact of summer heat waves and coastal upwelling in the Baltic Sea
Oceanologia 2020, 62(4PA), 511-524

Ülo Suursaar*
University of Tartu, Estonian Marine Institute, Tallinn, Estonia;
e-mail: ulo.suursaar@ut.ee, ys@sea.ee
*corresponding author

keywords: Global warming, Water temperature, Salinity, Marine heat waves, Satellite images, Breeze

Received 22 May 2020, Revised 6 August 2020, Accepted 10 August 2020, Available online 21 August 2020.


Under warming climates, heat waves (HWs) have occurred in increasing intensity in Europe. Also, public interest towards HWs has considerably increased over the last decades. The paper discusses the manifestations of the summer 2014 HW and simultaneously occurring coastal upwelling (CU) events in the Gulf of Finland. Caused by an anticyclonic weather pattern and persisting easterly winds, CUs evolved along the southern coast of the Gulf in four episodes from June to August. Based on data from coastal weather stations, 115 days-long measurements with a Recording Doppler Current Profiler (RDCP) oceanographic complex and sea surface temperature (SST) satellite images, the partly opposing impacts of these events are analysed. Occurring on the background of a marine HW (up to 26°C), the CU-forced SST variations reached about 20 degrees. At the 10 m deep RDCP mooring location, a drop from 21.5 to 2.9°C occurred within 60 hours. Salinity varied between 3.6 and 6.2 and an alongshore coastal jet was observed; the statistically preferred westerly current frequently flowed against the wind. Locally, the cooling effect of the CUs occasionally mitigated the overheating effects by the HWs both in the sea and on the marine-land boundary. However, in the elongated channel-like Gulf of Finland, upwelling at one coast is usually paired with downwelling at the opposite coast, and simultaneously or subsequently occurring HWs and CUs effectively contribute to heat transfer from the atmosphere to the water mass. Rising extremes of HWs and rapid variations by CUs may put the ecosystems under increasing stress.
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Dissolved oxygen variability in the southern Baltic Sea in 2013–2018
Oceanologia 2020, 62(4PA), 525-537

Daniel Rak1,*, Waldemar Walczowski1,*, Lidia Dzierzbicka-Głowacka1,*, Sergey Shchuka2,*
1Institute of Oceanology, Polish Academy of Sciences, Sopot, Poland;
e-mail: rak@iopan.gda.pl, walczows@iopan.gda.pl, dzierzb@iopan.gda.pl
2Shirshov Institute of Oceanology, Russian Academy of Sciences, Moscow, Russia;
e-mail: s_shchuka@mail.ru
*corresponding author

keywords: Inflows, Cod, Spermatozoa, Physical variability, Oxygenation

Received 7 May 2020, Revised 13 August 2020, Accepted 17 August 2020, Available online 26 August 2020.


This paper discusses changes in the dissolved oxygen concentration (DOC) in the southern Baltic Sea. The oxygenation of the whole water column was estimated. Monthly mean DOCs, as well as a detailed description of the annual surface layer dissolved oxygen (DO) cycle, are presented. The DO cycle at the surface is characterized by two maxima in March/April and November, and by two minima in July/August and December. The DO decline time after the major Baltic inflow (MBI) in 2014 was estimated at about 10 months for the Bornholm Deep and Słupsk Furrow. Whereas the Bornholm Basin was relatively well oxygenated, low oxygen concentrations (<4 mg l−1) were measured in the deep layer of the Gdańsk Deep throughout the inflow period. In addition, the cod spermatozoa activation layer together with the neutral egg buoyancy layer for the Bornholm Basin and Słupsk Furrow are discussed on the basis of the measured DOCs and the variability in hydrographic conditions.
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A turning point in the development of phytoplankton in the Vistula Lagoon (southern Baltic Sea) at the beginning of the 21st century
Oceanologia 2020, 62(4PA), 538-555

Janina Kownacka*, Joanna Całkiewicz*, Ryszard Kornijów*
Department of Fisheries Oceanography and Marine Ecology, National Marine Fisheries Research Institute, Gdynia, Poland
e-mail: anina.kownacka@mir.gdynia.pl, jcalkiewicz@mir.gdynia.pl, rkornijow@mir.gdynia.pl
*corresponding author

keywords:Multiannual changes, Zooplankton/phytoplankton ratio, Phytoplankton community shift, Nutrients, Transparency

Received 24 February 2020, Revised 14 August 2020, Accepted 17 August 2020, Available online 27 August 2020.


Phytoplankton community structure was studied from 2002 to 2016 in the Vistula Lagoon (southern Baltic Sea) in the context of the 2010 shift in its population, as well as the reason for this shift and its environmental impact. This evident shift was indicated by Multidimensional Scaling at the Bray Curtis similarity level of 31%. Before 2010, the primary components of phytoplankton were Cyanobacteria (up to 98% of the biomass, October 2007) and Chlorophyta (40%, July 2002). After 2010, the contribution of Cyanobacteria considerably decreased, and the proportions of other phyla increased. The total phytoplankton biomass positively correlated with phosphorus, and Cyanobacteria biomass with silica. Evident changes were also observed in the seasonal dynamics of phytoplankton. Before 2010, the highest values of biomass occurred in autumn, and were related to high biomass of Cyanobacteria. Higher biomass has been recently reached in spring, during the dominance of Ochrophyta associated with Chlorophyta, Charophyta, and Cryptophyta. Generalised additive models showed a significant decreasing trend of the total phytoplankton biomass, Cyanobacteria, Chlorophyta, and flagellates, suggesting a decrease in eutrophication. This trend is concurrent with a considerable increase in the ratio of zooplankton to phytoplankton biomass since 2010. The increased ratio, however, did not result from elevated zooplankton biomass, but from the drop in phytoplankton biomass. Therefore, the most probable reason for the decrease in phytoplankton biomass was the simultaneous decrease in the concentration of all nutrients. The potential additional impact of filtration by a new alien bivalve Rangia cuneata G. B. Sowerby I, 1832 is also discussed.
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Corrigendum to “The inflow in the Baltic Proper as recorded in January–February 2015” [Oceanologia 58 (2016) 241–247]
Oceanologia 2020, 62(4PA), Page I

Daniel Rak*
Institute of Oceanology, Polish Academy of Sciences, Sopot, Poland;
e-mail: rak@iopan.gda.pl

Available online 15 October 2020. 26 August 2019, Revised 13 February 2020, Accepted 13 February 2020, Available online 28 February 2020.

Refers to:
The inflow in the Baltic Proper as recorded in January–February 2015
Oceanologia, Volume 58, Issue 3, July–September 2016, Pages 241-247
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