Oceanologia No. 52 (3) / 10

Contents

Papers

Papers


Sea surface temperature retrieval from MSG/SEVIRI data in the Baltic Sea area
Oceanologia 2010, 52(3), 331-344
http://dx.doi.org/10.5697/oc.52-3.331

Monika Woźniak, Adam Krężel*
Institute of Oceanography, University of Gdańsk,
al. Marszałka Piłsudskiego 46, PL-81-378 Gdynia, Poland;
e-mail: oceak@univ.gda.pl
*corresponding author

keywords: sea surface temperature, Baltic, Meteosat

Received 12 November 2009, revised 6 July 2010, accepted 30 July 2010.

Abstract

The aim of the paper was to confirm the proposition that the classical SST algorithms MCSST and NLSST originally prepared for AVHRR data could also be used for Meteosat/SEVIRI data with satisfactory accuracy in the mid-latitude region, where the spatial resolution is about 7x7 km. The research was performed in the southern Baltic Sea (between 13°E 53°N and 21°E 58°N). Data were collected in all the seasons of 2007. The coefficients were found by means of regression analysis. SSTs determined on the basis of AVHRR data were used in the regression analysis instead of in situ data. A set of paired AVHRR and SEVIRI images spaced no more than 8 minutes apart were compared. The results show that the method is capable of producing sea surface temperatures with a statistical error (standard deviation) of 1°C.

  References ref
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Spatial and interannual variations of seasonal sea surface temperature patterns in the Baltic Sea
Oceanologia 2010, 52(3), 345-362
http://dx.doi.org/10.5697/oc.52-3.345

Katarzyna Bradtke*, Agnieszka Herman, Jacek A. Urbański
Institute of Oceanography, University of Gdańsk,
al. Marszałka Piłsudskiego 46, PL-81-378 Gdynia, Poland;
e-mail: ocekb@univ.gda.pl
*corresponding author

keywords: sea surface temperature, seasonality, global climate change, Baltic Sea

Received 12 April 2010, revised 2 June 2010, accepted 1 July 2010.

Abstract

On the basis of monthly averaged satellite data, this study examined how the annual cycle of the Baltic Sea surface temperature (SST) varied spatially and temporally during the period 1986-2005. We conclude that there are two main thermal seasons in the Baltic Sea separated only by short transitional periods - spring lasting about one month, and autumn lasting two months. Generally speaking, summer covers the part of the year from June to October with the highest monthly mean SST in August. Winter, with a minimum monthly mean SST in February in shallow waters or in March in deeper areas, lasts from December to April. As a result of climate changes over the Baltic Sea region, strong positive trends in SST occur in the summer months. In consequence, the period with extremely high sea surface water temperatures has become slightly longer in the central Baltic. In the last decade winter changes in SST display zero or even negative tendencies. The investigated period was characterized by an annual increase in mean temperatures of about 0.03-0.07°C. However, the rates of monthly mean SST changes were sometimes more than three times as high.

  References ref
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On the transformation of long gravity waves on a sloping beach:
Oceanologia 2010, 52(3), 363-389
http://dx.doi.org/10.5697/oc.52-3.363

Jan Kazimierz Szmidt*, Benedykt Hedzielski
Institute of Hydro-Engineering, Polish Academy of Sciences,
Waryńskiego 17, PL-71-310 Szczecin, Poland;
e-mail: jks@ibwpan.gda.pl
*corresponding author

keywords: long wave, wave transformation, sloping beach, wave run-up

Received 1 July 2009, revised 31 May 2010, accepted 2 June 2010.

This work was supported by the Polish Ministry of Science and Higher Education under grant No. N N506 378134.

Abstract

The transformation of long water waves arriving at a sloping beach is investigated. An approximate theory is presented for plane periodic waves propagating in water of non-uniform depth. The theoretical description of the phenomenon, based on certain kinematic assumptions, is formulated in the material variables, and the solution is constructed by applying the Hamilton variational principle. In order to assess the accuracy of the formulation and to learn more about long wave transformation, experimental measurements were carried out in a laboratory flume. In the experiments, a water wave, generated by a piston-type wave maker placed at one end of the flume, propagated towards a rigid inclined ramp installed at the other end of the flume. The wave transformation along the direction of its propagation was recorded by a set of wave gauges installed along the flume. The wave run-up on the sloping beach was measured with a special conductivity gauge placed alongside the ramp. Comparison of the theoretical results with experimental data indicates that the proposed theoretical formulation provides a good description of the main features of wave transformation behaviour over a sloping beach, except in the vicinity of the shore point, where some discrepancies occur.

  References ref
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Waves, currents and sea level variations along the Letipea - Sillamäe coastal section of the southern Gulf of Finland
Oceanologia 2010, 52(3), 391-416
http://dx.doi.org/10.5697/oc.52-3.391

Ülo Suursaar
Estonian Marine Institute, University of Tartu,
Mäealuse 14, EE-12618 Tallinn, Estonia;
e-mail: ulo.suursaar@ut.ee

keywords: wave hindcast, upwelling, coastal jets, climate change, RDCP, Baltic Sea

Received 17 February 2010, revised 7 June 2010, accepted 21 June 2010.

The study was partially supported by the Estonian target financed project 0104s08, ESF grant project 7609, as well as by Kunda EstCell and Port of Sillamäe monitoring contracts.

Abstract

Variations in the hydrodynamic conditions were studied on the basis of 336 days of measurements with a Doppler current profiler. With wave data as a calibration reference, a semi-empirical hindcast of wave parameters is presented in the fetch-limited near-shore area for the period 1966-2008. A resultant 4-6 cm s-1 westward current dominated along the coast. Occasional fast sub-surface westward currents under modest wind forcing, as well as asymmetrical vertical profiles for westward and eastward currents indicated the influence of upwelling-related baroclinic coastal jets. The average frequency of upwelling was estimated at 17%; some of the events were identified in near-homothermic winter conditions on the basis of salinity and multi-layer flow records. While the mean sea level trend at Narva-Jõesuu roughly approximated the global estimates for 1899-2009, the annual maximum sea level increase was 5-8 mm yr-1. Both mean and maximum wave heights declined as a result of decreasing winds from the north.

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Baroclinic Rossby radius of deformation in the southern Baltic Sea
Oceanologia 2010, 52(3), 417-429
http://dx.doi.org/10.5697/oc.52-3.417

Robert Osiński*, Daniel Rak, Waldemar Walczowski, Jan Piechura
Institute of Oceanology, Polish Academy of Sciences,
Powstańców Warszawy 55, PL-81-712 Sopot, Poland;
e-mail: roberto@water.iopan.gda.pl
*corresponding author

keywords: baroclinic Rossby radius, Brunt-Väisälä frequency, southern Baltic Sea, mesoscale dynamics

Received 29 January 2010, revised 8 April 2010, accepted 6 August 2010.

This work was supported by the Polish State Committee of Scientific Research under grant No. N N305 111636.

Abstract

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.

  References ref
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Fluorescence measured in situ as a proxy of CDOM absorption and DOC concentration in the Baltic Sea
Oceanologia 2010, 52(3), 431-471
http://dx.doi.org/10.5697/oc.52-3.431

Piotr Kowalczuk*, Monika Zabłocka, Sławomir Sagan, Karol Kuliński
Institute of Oceanology, Polish Academy of Sciences,
Powstańców Warszawy 55, PL-81-712 Sopot, Poland;
e-mail: piotr@iopan.gda.pl
*corresponding author

keywords: CDOM absorption, DOC concentration, Baltic Sea

Received 20 April 2010, revised 27 July 2010, accepted 9 August 2010.

This study was funded by the Polish Ministry of Science and Higher Education through grant No. NN 306-2942-33 for the research project entitled "Spectral properties of CDOM absorption and fluorescence and their relationship with Dissolved Organic Carbon concentration in the Baltic Sea". The principle investigator was Piotr Kowalczuk. The research infrastructure, including access to the research vessel r/v "Oceania", was provided by the Institute of Oceanology, Polish Academy of Sciences, Sopot, Poland. Partial support for this study was also provided by the project Satellite Monitoring of the Baltic Sea Environment - SatBałtyk, co-founded by the European Union through European Regional Development Fund contract No. POIG 01.01.02-22-011/09.

Abstract

This study presents results from field surveys performed in 2008 and 2009 in the southern Baltic in different seasons. The main goal of these measurements was to identify the empirical relationships between DOM optical properties and DOC. CDOM absorption and fluorescence and DOC concentrations were measured during thirteen research cruises. The values of the CDOM absorption coefficient at 370 nm aCDOM(370) ranged from 0.70 m-1 to 7.94 m-1, and CDOM fluorescence intensities (ex./em. 370/460) IFl, expressed in quinine sulphate equivalent units, ranged from 3.88 to 122.97 (in filtered samples). Dissolved organic carbon (DOC) concentrations ranged from 266.7 to 831.7 µM C. There was a statistically significant linear relationship between the fluorescence intensity measured in the filtered samples and the CDOM absorption coefficient aCDOM(370), R2 = 0.87. There was much more scatter in the relationship between the fluorescence intensity measured in situ (i.e. in unprocessed water samples) and the CDOM absorption coefficient aCDOM(370), resulting in a slight deterioration in the coefficient of determination R2 = 0.85. This indicated that the presence of particles could impact fluorometer output during in situ deployment. A calibration experiment was set up to quantify particle impact on the instrument output in raw marine water samples relative to readings from filtered samples. The bias calculated for the absolute percentage difference between fluorescence intensities measured in raw and filtered water was low (-2.05%), but the effect of particle presence expressed as the value of the RMSE was significant and was as high as 35%. Both DOM fluorescence intensity (in raw water and filtered samples) and the CDOM absorption coefficient aCDOM(370) are highly correlated with DOC concentration. The relationship between DOC and the CDOM absorption coefficient aCDOM(370) was better (R2 = 0.76) than the relationship between DOC and the respective fluorescence intensities measured in filtered and raw water (R2 = 0.61 and R2 = 0.56). The seasonal cycle had an impact on the relationship between DOC and CDOM optical properties. The hyperbolic relationships between aCDOM(370) vs. carbon-specific absorption coefficient a*CDOM(370), and IFl vs. the ratio of fluorescence intensity to organic carbon concentration IFl/DOC were very good. The discharge and mixing of riverine waters is a primary driver of variability in DOC and CDOM optical properties in the surface waters of the southern Baltic Sea, since all the parameters considered are negatively correlated with salinity. It was found that there was a positive trend of increasing values of DOM optical parameters with salinity increase (within a range of 8-12) in deep water below the permanent pycnocline. Evidence is also presented to show that late-summer photodegradation was responsible for the depletion of CDOM florescence intensities in the mixed layer above the seasonal thermocline. It was further demonstrated that the DOC concentration increases in the stagnant waters of the Baltic Sea deeps. The Integrated Optical-Hydrological Probe, which registers high-resolution vertical profiles of salinity, temperature, CDOM and the optical properties of water, confirmed that DOM optical proxies can be used in studies of DOM biogeochemical cycles in the Baltic Sea.

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Restructuring of a zooplankton community by perturbation from a wind-forced coastal jet
Oceanologia 2010, 52(3), 473-497
http://dx.doi.org/10.5697/oc.52-3.473

Ole-Petter Pedersen1,*, Kurt S. Tande2, Chaolun Li3, Meng Zhou4
1University of Tromsø,
9037 Tromsø, Norway;
e-mail: ole.p.pedersen@uit.no
*corresponding author
2Bodø University College,
8049 Bodø, Norway
3Institute of Oceanology, Chinese Academy of Sciences,
266071 Qingdao, P. R. China
4Department of Environmental, Earth and Ocean Sciences, University of Massachusetts,
Boston, MA 02125, USA

keywords: zooplankton, filament, intrusion, restructuring, mesoscale

Received 2 June 2010, revised 23 September 2010, accepted 26 August 2010.

This work was supported by the Research Council of Norway, contract No. 140290/140.

Abstract

The impact of transient wind events on an established zooplankton community was observed during a field survey in a coastal region off northern Norway in May 2002. A transient wind event induced a coastal jet/filament intrusion of warm, saline water into our survey area where a semi-permanent eddy was present. There was an abrupt change in zooplankton community structure within 4-7 days of the wind event, with a change in the size structure, an increase in lower size classes less than 1 mm in equivalent spherical diameter (ESD) and a decrease in larger size classes greater than 1.5 mm in ESD. The slope of zooplankton biovolume spectra changed from -0.6 to -0.8, consistent with the size shifting towards smaller size classes. This study shows that even well established zooplankton communities are susceptible to restructuring during transient wind events, and in particular when wind forcing induces horizontal currents or filaments.

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Plutonium isotopes 238Pu, 239+240Pu, 241Pu and 240Pu/239Pu atomic ratios in the southern Baltic Sea ecosystem
Oceanologia 2010, 52(3), 499-512
http://dx.doi.org/10.5697/oc.52-3.499

Dagmara I. Strumińska-Parulska*, Bogdan Skwarzec
Analytics and Environmental Radiochemistry Chair, Faculty of Chemistry, University of Gdańsk,
Sobieskiego 18/19, PL-80-952 Gdańsk, Poland;
e-mail: strumyk@chem.univ.gda.pl
*corresponding author

keywords: plutonium, 238Pu, 239+240Pu, 241Pu and 240Pu/239Pu atomic ratio, Baltic Sea, Chernobyl accident, atmospheric fallout

Received 5 January 2009, revised 31 August 2010, accepted 3 September 2010.

This study was supported financially by the Polish Ministry of Science and Higher Education under grant No. DS/8460-4-0176-0.

Abstract

The paper summarizes the results of plutonium findings in atmospheric fallout samples and marine samples from the southern Baltic Sea during our research in 1986-2007. The activities of 238Pu and 239+240Pu isotopes were measured with an alpha spectrometer. The activities of 241Pu were calculated indirectly by 241Am activity measurements 16-18 years after the Chernobyl accident. The 240Pu/239Pu atomic ratios were measured using accelerator mass spectrometry (AMS).
    The 241Pu activities indicate that the main impact of the Chernobyl accident was on the plutonium concentration in the components of the Baltic Sea ecosystem examined in this work. The highest 241Pu/239+240Pu activity ratio was found in sea water (140 ± 33). The AMS measurements of atmospheric fallout samples collected during 1986 showed a significant increase in the 240Pu/239Pu atomic ratio from 0.29 ± 0.04 in March 1986 to 0.47 ± 0.02 in April 1986.

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The different uses of sea space in Polish Marine Areas: is conflict inevitable?
Oceanologia 2010, 52(3), 513-530
http://dx.doi.org/10.5697/oc.52-3.513

Jan Marcin Węsławski1,*, Jacek Urbański2, Lucyna Kryla-Staszewska2, Eugeniusz Andrulewicz3, Tomasz Linkowski3, Emil Kuzebski3, Włodzimierz Meissner4, Zbigniew Otremba5, Joanna Piwowarczyk1
1Institute of Oceanology, Polish Academy of Sciences,
Powstańców Warszawy 55, PL-81-712 Sopot, Poland;
e-mail: weslaw@water.iopan.gda.pl
*corresponding author
2Geoinformatics Laboratory, Institute of Oceanography, University of Gdańsk,
al. Marszałka Piłsudskiego 46, PL-81-378 Gdynia, Poland,
3Sea Fisheries Institute,
Kołłątaja 1, PL-81-332 Gdynia, Poland,
4Avian Ecophysiology Unit, Department of Vertebrates Ecology and Zoology, University of Gdańsk,
al. Legionów 9, PL-80-441 Gdańsk, Poland
5Gdynia Maritime University,
Morska 87, PL-81-225 Gdynia, Poland

keywords: marine protected areas, spatial planning, sea space use

Received 22 March 2010, revised 26 July 2010, accepted 8 August 2010.

Abstract

Seven major types of sea space use (Nature Protection Measures, Fisheries Exploitation, Geological Exploitation, Recreation, Large Infrastructures, Navigation, Military uses) in the Polish Marine Areas are presented in terms of how much space is used (km2) for each use and the degree of overlap among the different uses. The greatest degree of conflict is noted with regard to Nature Protection (which overlaps with 60% of the areas used for Recreation and Geological Exploitation), and Fisheries Exploitation (which overlaps with 60% of the areas used for Nature Protection, Recreation, Infrastructure and Navigation). On the other hand, Fisheries Exploitation areas are the least disturbed by other users, and its major competitor is Nature Protection, which claims 20% of the areas used by fisheries. A GIS-based map that illustrates the degree of conflict is included, and the authors suggest participatory management as the proper way to minimize conflicts over sea space use and to promote the effective protection of natural resources.

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