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Attributing mean circulation patterns to physical phenomena in the Gulf of Finland

100%

Westerlund A., Tuomi L., Alenius P., Miettunen E., Vankevich R. E.

Oceanologia

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2018

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tom 60

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nr 1

We studied circulation patterns in the Gulf of Finland, an estuary-like sub-basin of the Baltic Sea. According to previous observations and model results, the long-term mean circulation in the gulf is cyclonic and mainly density driven, whereas short-term circulation patterns are wind driven. We used the high-resolution 3D hydrodynamic model NEMO to simulate the years 2012–2014. Our aim was to investigate the role of some key features, like river runoff and occasional events, in the formation of the circulation patterns. Our results show that many of the differences visible in the annual mean circulation patterns from one year to another are caused by a relatively small number of high current speed events. These events seem to be upwelling-related coastal jets. Although the Gulf of Finland receives large amounts of fresh water in river runoffs, the inter-annual variations in runoff did not explain the variations in the mean circulation patterns.

2

Regional algorithms for the estimation of chlorophyll and suspended matter concentration in the Gulf of Finland from MODIS-Aqua satellite data

100%

Vazyulya S., Khrapko A., Kopelevich O., Burenkov V., Eremina T., Isaev A.

Oceanologia

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2014

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tom 56

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nr 4

3

Variability of currents over the southern slope of the Gulf of Finland

100%

Suhhova I., Pavelson J., Lagemaa P.

Oceanologia

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2015

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tom 57

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nr 2

4

Spatio-temporal variations in hydro-physical and -chemical parameters during a major upwelling event off the Southern coast of the Gulf of Finland in summer 2006

100%

Suursaar U., Aps R.

Oceanologia

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2007

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tom 49

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nr 2

The objective of the paper is to document and examine the major upwelling event that occurred along the northern coast of Estonia in August 2006. With a horizontal extension of 360 km, the event was caused by persistent easterlies and was noticed by a large number of holidaymakers, as it reduced the temperature of the coastal sea to a chilly 5–10◦C for about a month. In situ measurements from an RDCP current profiler revealed an along-wind coastal jet of up to 60 cm s−1 and a weak near-bottom countercurrent. The depths of the pycnocline and nutricline rose. The maximum drop in water temperature was 16◦C, that of salinity was 3.6 PSU. Analysis of satellite images confirmed the large extension and the prominence of the event.

5

Modelling nitrogen and phosphorus limitation on phytoplankton growth in Narva Bay, South-Eastern Gulf of Finland

100%

Lessin G., Lips I., Raudsepp U.

Oceanologia

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2007

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tom 49

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nr 2

The relative roles of nitrogen and phosphorus in the limitation of phytoplankton growth in Narva Bay, south-eastern Gulf of Finland, were studied by combining the results of numerical modelling and nutrient enrichment experiments.Mo delled biomass-based intracellular nutrient concentrations (nutrient functions) were used to estimate the limiting nutrient in Narva Bay.Nutr ient functions – NF ∈ [0; 1] for nitrogen and PF ∈ [0; 1] for phosphorus – define the dependence of the phytoplankton growth rate on nutrients: NF = PF = 1 corresponds to nonlimitation of phytoplankton growth by nutrients, whereas NF = 0 or PF = 0 to zero growth.T he biotests indicated the response of phytoplankton growth to an increase in nutrient concentration in the surrounding water.Thr ee locations were selected for detailed analyses of temporal variations in the nutrient functions: the offshore station N12, station N8 at the mouth of the River Narva, and coastal station 38.T he biotests were performed at the same stations. NF and PF reached values of 0.9 prior to the spring bloom. With the onset of the spring bloom, NF decreased rapidly and remained below 0.1 in the open part of Narva Bay for the rest of that period.I n the coastal zone, NF was in excess of 0. 1, with a local maximum in the river mouth area. PF decreased to 0.3–0.4 in the open bay after the spring bloom.I n the coastal zone PF remained above 0.4, with a certain increase from the midsummer minimum towards the end of summer.The numerical modelling results clearly show that nitrogen limits phytoplankton growth in Narva Bay.Ph osphorus limitation may occur only for a limited period and over a limited area at the Narva River mouth and other coastal locations.I n general, the biotests backed up the modelling results, the main exception being in the open bay during summer.The model does not account for nitrogen fixation, however.S ince N-fixing cyanobacteria were prevalent in the offshore area, the addition of phosphorus led to enhanced phytoplankton growth at station N12.

6

Combined impact of summer heat waves and coastal upwelling in the Baltic Sea

84%

Suursaar U.

Oceanologia

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2020

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tom 62

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nr 4PA

7

The progress in knowledge of physical oceanography of the Gulf of Finland: e review for 1997-2007

84%

Soomere T., Myrberg K., Lepparanta M., Nekrasov A.

Oceanologia

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2008

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tom 50

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nr 3

287-362

The main findings of studies of the physical oceanography of the Gulf of Finland (GoF) during 1997–2007 are reviewed. The aim is to discuss relevant updates published in international peer-reviewed research papers and monographs, bearing in mind that a comprehensive overview of the studies up to the mid-1990s is available (Alenius et al. 1998). We start the discussion with updates on the basic hydrographical and stratification conditions, and progress in the understanding of atmospheric forcing and air-sea interaction. Advances in the knowledge of basinscale and mesoscale dynamics are summarised next. Progress in circulation and water exchange dynamics has been achieved mostly by means of numerical studies. While the basic properties of circulation patterns in the gulf have been known for a century, new characteristics and tools such as water age, renewal index, and high-resolution simulations have substantially enriched our knowledge of processes in the Gulf of Finland during the last decade. We present the first overview of both status and advances in optical studies in this area. Awareness in this discipline has been significantly improved as a result of in situ measurements. Our understanding of the short- and long-term behaviour of the sea level as well as knowledge of the properties of both naturally and anthropogenically induced surface waves have expanded considerably during these ten years. Developments in understanding the ice conditions of the Gulf of Finland complete the overview, together with a short discussion of the gulf’s future, including the response to climate change. Suggestions for future work are outlined.

8

Influence of landfast ice on the hydrography and circulation of the Baltic Sea coastal zone

84%

Merkouriadi I., Lepparanta M.

Oceanologia

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2013

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tom 55

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nr 1

9

Life in sympatry: coexistence of native Eurytemora affinis and invasive Eurytemora carolleeae in the Gulf of Finland (Baltic Sea)

84%

Sukhikh N., Souissi A., Souissi S., Holl A.-C., Schizas N. V., Alekseev V.

Oceanologia

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2019

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tom 61

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nr 2

10

Impact of ship-borne nitrogen deposition on the Gulf of Finland ecosystem: an evaluation

84%

Raudsepp U., Laanemets J., Maljutenko I., Hongisto M., Jalkanen J.-P.

Oceanologia

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2013

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tom 55

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nr 4

11

Winter upwelling in the Gulf of Finland, Baltic Sea

84%

Suursaar U.

Oceanologia

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2021

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tom 63

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nr 3

12

Development of the sandy coast: Hydrodynamic and morphodynamic conditions (on the example of the Eastern Gulf of Finland)

84%

Divinsky B. V., Ryabchuk D. V., Kosyan R. D., Sergeev A. Y.

Oceanologia

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2021

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tom 63

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nr 2

13

Periodic variability of currents induced by topographically trapped waves in the coastal zone in the Gulf of Finland

84%

Talpsepp L.

Oceanologia

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2006

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tom 48

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nr S

The aim of this paper is to examine the water exchange regime between the bays of northern Estonia (Pakri Bay, Ihasalu Bay and Muuga Bay) and the open part of the Gulf of Finland. To this end, the current measurements and CTD-castings performed at the border of the bays and the open part of the Gulf of Finland in summer 1994, 1995–96 and 1997 are analysed. All the current measurements displayed one feature in common: the existence of periodic variability with a current amplitude of between 5 and 25 cm s−1 and a variability period of 3–4 days (68 hours in Pakri Bay, 72 hours in Muuga Bay and 78 hours in Ihasalu Bay). The amplitudes of this variability differed during different time periods of the experiment and in different parts of the southern Gulf of Finland. The hypothesis was propounded that this variability is the result of bottom-trapped waves, as had been found in many other regions of the Baltic Sea (Aitsam & Talpsepp 1982, Talpsepp 1983). To interpret the results of the measurements, a model of bottom-trapped waves for this region was used. This was the short-wave version of Huthnance’s (1978) numerical model of coastal-trapped waves, according to which the wave parameters for the experimental regions were calculated. Comparison of the model and the measurements implies that coastal-trapped waves do exist off the southern coast of the Gulf of Finland.

14

Functional response of midsummer planktonic and benthic communities in the Neva Estuary (Eastern Gulf of Finland) to anthropogenic stress

84%

Golubkov S. M., Alimov A. F., Telesh I. V., Anokhina L. E., Maximov A. A., Nikulina V. N., Pavel'eva E.B., Panov V. E.

Oceanologia

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2003

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tom 45

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nr 1

Long-termhydrobiological research has shown that the functioning of the ecosystem of the Neva Estuary, one of the largest Baltic estuaries, has changed greatly since the beginning of the 20th century. Ineffective local water management in St.Petersburg during the last twenty years has stimulated the development of a natural ‘biological plug’ in the salt barrier zone in the inner part of the estuary and has altered the ecosystem’s functioning. These changes include an increase in primary production, in the primary production : organic matter decomposition ratio, and in pelagic-benthic coupling. It has also given rise to filamentous algae blooms and intensive secondary pollution in the coastal zone of the Neva Estuary. The primary production of phytoplankton in the inner part of the estuary has reached 2.3 gC m−2, that of the filamentous algae Cladophora glomerata 5.5 gC m−2; these figures are much higher than in other regions of the Gulf of Finland.

15

Large halocline variations in the Northern Baltic Proper and associated meso- and basin-scale processes

84%

Elken J., Malkki P., Alenius P., Stipa T.

Oceanologia

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2006

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tom 48

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nr S

The Northern Baltic Proper is a splitting area of the Baltic Sea saline water route towards the two terminal basins – the Gulf of Finland and the Western Gotland Basin. Large halocline variations (vertical isopycnal displacements of more than 20 m, intra-halocline current speeds above 20 cm s−1) appear during and following SW wind events, which rapidly increase the water storage in the Gulf of Finland and reverse the standard estuarine transport, causing an outflow in the lower layers. In the channel of variable topography, basin-scale barotropic flow pulses are converted into baroclinic mesoscale motions such as jet currents, sub-surface eddies and lowfrequency waves. The associated dynamics is analysed by the results from a special mesoscale experiment, routine observations and numerical modelling.

16

Recent observations of the sex ratio and maturity ogive of Baltic sprat in the North-Eastern Baltic Sea

84%

Kaljuste O., Raid T.

Bulletin of the Sea Fisheries Institute

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2002

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nr 3

17

Downwelling-related mesoscale motions at the entrance to the Gulf of Finland: observations and diagnosis

84%

Laanemets J., Pavelson J., Lips U., Kononen K.

Oceanological and Hydrobiological Studies

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2005

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tom 34

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nr 2

18

Waves, currents and sea level variations along the Letipea - Sillamäe coastal section of the Southern Gulf of Finland

67%

Suursaar U.

Oceanologia

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2010

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tom 52

|

nr 3

391-416

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.

19

Spatial patterns of the wave climate in the Baltic Proper and the Gulf of Finland

67%

Soomere T., Raamet A.

Oceanologia

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2011

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tom 53

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nr (1-TI)

We make an attempt to consolidate results from a number of recent studies into spatial patterns of temporal variations in Baltic Sea wave properties. The analysis is based on historically measured and visually observed wave data, which are compared with the results of numerical hindcasts using both simple fetch-based one-point models and contemporary spectral wave models forced with different wind data sets. The focus is on the eastern regions of the Baltic Sea and the Gulf of Finland for which long-term wave data sets are available. We demonstrate that a large part of the mismatches between long-term changes to wave properties at selected sites can be explained by the rich spatial patterns in changes to the Baltic Sea wave fields that are not resolved by the existing wave observation network. The spatial scales of such patterns in the open sea vary from >500 km for short-term interannual variations down to about 100 km for long-term changes.

20

Monitoring the effect of upwelling on the chlorophyll a distribution in the Gulf of Finland (Baltic Sea) using remote sensing and in situ data

67%

Uiboupin R., Laanemets J., Sipelgas L., Raag L., Lips I., Buhhalko N.

Oceanologia

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2012

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tom 54

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nr 3

The spatio-temporal variability of chlorophyl a (Chl a) caused by a sequence of upwelling events in the Gulf of Finland in July–August 2006 was studied using remote sensing data and field measurements. Spatial distributions of sea surface temperature (SST) and Chl a concentration were examined using MODIS and MERIS data respectively. The MERIS data were processed with an algorithm developed by the Free University of Berlin (FUB) for case 2 waters. Evaluation of MERIS Chl a versus in situ Chl a showed good correlation (r2 = 0.67), but the concentration was underestimated. The linear regression for a 2 h window was applied to calibrate MERIS Chl a. The spatio-temporal variability exhibited the clear influence of upwelling events and related filaments on Chl a distribution in the western and central Gulf. The lowest Chl a concentrations were recorded in the upwelled water, especially at the upwelling centres, and the highest concentrations (13 mg m−3) were observed about two weeks after the upwelling peak along the northern coast. The areas along the northern coast of upwelled water (4879 km2) on the SST map, and increased Chl a (5526 km2) two weeks later, were roughly coincident. The effect of upwelling events was weak in the eastern part of the Gulf, where Chl a concentration was relatively consistent throughout this period.

Ograniczanie wyników

Attributing mean circulation patterns to physical phenomena in the Gulf of Finland

Regional algorithms for the estimation of chlorophyll and suspended matter concentration in the Gulf of Finland from MODIS-Aqua satellite data

Variability of currents over the southern slope of the Gulf of Finland

Spatio-temporal variations in hydro-physical and -chemical parameters during a major upwelling event off the Southern coast of the Gulf of Finland in summer 2006

Modelling nitrogen and phosphorus limitation on phytoplankton growth in Narva Bay, South-Eastern Gulf of Finland

Combined impact of summer heat waves and coastal upwelling in the Baltic Sea

The progress in knowledge of physical oceanography of the Gulf of Finland: e review for 1997-2007

Influence of landfast ice on the hydrography and circulation of the Baltic Sea coastal zone

Life in sympatry: coexistence of native Eurytemora affinis and invasive Eurytemora carolleeae in the Gulf of Finland (Baltic Sea)

Impact of ship-borne nitrogen deposition on the Gulf of Finland ecosystem: an evaluation

Winter upwelling in the Gulf of Finland, Baltic Sea

Development of the sandy coast: Hydrodynamic and morphodynamic conditions (on the example of the Eastern Gulf of Finland)

Periodic variability of currents induced by topographically trapped waves in the coastal zone in the Gulf of Finland

Functional response of midsummer planktonic and benthic communities in the Neva Estuary (Eastern Gulf of Finland) to anthropogenic stress

Large halocline variations in the Northern Baltic Proper and associated meso- and basin-scale processes

Recent observations of the sex ratio and maturity ogive of Baltic sprat in the North-Eastern Baltic Sea

Downwelling-related mesoscale motions at the entrance to the Gulf of Finland: observations and diagnosis

Waves, currents and sea level variations along the Letipea - Sillamäe coastal section of the Southern Gulf of Finland

Spatial patterns of the wave climate in the Baltic Proper and the Gulf of Finland

Monitoring the effect of upwelling on the chlorophyll a distribution in the Gulf of Finland (Baltic Sea) using remote sensing and in situ data