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1

Model estimates of microplastic potential contamination pattern of the eastern Gulf of Finland in 2018

Martyanov Stanislav D., Isaev Alexey, Ryabchenko Vladimir A.

Oceanologia

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2023

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Vol. 65 (1)

86--99

EN

The work is focused on the assessment of microplastics transport and distribution in the eastern part of the Gulf of Finland by means of numerical modeling. In the present study only the riverine sources of microplastics are taken into account. The presented model also accounts for possible sink of suspended microplastic particles into sediments due to simple parameterization of biogeochemical processes such as biofouling and ingestion by zooplankton. Two basic scenarios with different initial fall velocities of suspended microplastic particles, 0.2 m/day and 1.2 m/day, are discussed. The distribution of microplastics coming with the riverine waters of the Neva, Luga, and Narva rivers has been investigated, based on a numerical hydrodynamical hindcast of the year 2018. Model simulations show that the transport of suspended microplastics occurs along the northern coast of the considered area more intensively compared to the southern coast, especially in the easternmost shallow part of the gulf. The results are in a good agreement with other studies focused on the microplastic pollution of the Neva Bay, and with available observational data. The presented results and developed model can be useful tools aimed to assess the intensity and mechanisms of microplastic pollution of the eastern Gulf of Finland. The results can be used in the selection of areas for future environmental monitoring of microplastics pollution of the eastern part of the Gulf of Finland.

2

Species-level associations of phytoplankton with environmental variability in the Neva Estuary (Baltic Sea)

Golubkov Mikhail, Nikulina Vera, Golubkov Sergey

Oceanologia

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2021

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No. 63 (1)

149--162

EN

Changes in phytoplankton communities due to anthropogenic nutrient load and climate change often lead to eutrophication and harmful algal blooms that can affect biogeochemical cycling. However, little is known about the specific responses of various species to environmental variables. 17-year long data on the midsummer phytoplankton biomass in the Neva Estuary were analyzed to show the changes in the composition of phytoplankton in relation to water depth, transparence, salinity, temperature, concentrations of total phosphorus and chlorophyll a, and plankton primary production. One hundred seventy-four species and forms from eight taxonomic classes were found in phytoplankton. Fifteen species were potentially harmful. The most diverse and abundant groups were cyanobacteria, green algae and diatoms. Canonical Correspondence Analysis showed that the biomass of various species from each phytoplankton group correlated differently with environmental factors. However, within each group, there were some predominant trends in the correlative response to changes in environmental variables. The biomass of cyanobacteria was high in the middle and lower reaches of the estuary and, in general, positively correlated with water salinity. The biomass of most species of green algae and diatoms correlated negatively with it. These algae showed a positive trend in biomass in the upper and middle reaches of the estuary during the last decades that may be explained by changes in weather conditions. Taking into account that climate models predict future increases in precipitation and temperature in the northern Baltic, the future expansion of freshwater phytoplankton species in estuaries of the northern Baltic Sea is very likely.

3

Integrated Assessment of Groundwater Pollution from the Landfill of Sewage Sludge

Dregulo Andrey Mikhailovich, Bobylev Nikolai Gennadievich

Journal of Ecological Engineering

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2021

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Vol. 22, nr 1

68--75

EN

The purpose of this study was to assess the groundwater contamination from a sewage sludge landfill. The analysis was carried out in 2017 in accordance with the requirements of the national legislation for monitoring landfills and priority pollutants. The samples of groundwater from the landfill were taken from 25 observation wells, from depths of 45–60 m. The status and dynamics of changes in the landfill groundwater quality were estimated according to the data from the groundwater observation wells of the city observation network with regard to the chemical composition of groundwater and national standards of groundwater quality. The forecast estimates of a low level of pollutants entering groundwater through the soils characterized by low filtration properties were not justified. The concentration of heavy metals in groundwater was within the following range: Fe > Mn > Zn > Al > Cu > Ni > Pb > Cd > Hg. The excess concentration of the nitrogen-containing pollutants was observed within the range from 1.5 to 76 (on average 10 times) above the background value. The organic contamination of landfill groundwater (COD) is 2–9 times and BOD5 – 1.5–3 times higher than the average background value of groundwater observation wells in the city network. The probable cause for the pollutants entry into groundwater is associated with lithogenous and exogenous fracturing of the rocks and insufficient efficiency of the existing anti-filtration system of the landfill.

4

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

Sukhikh Natalia, Souissi Anissa, Souissi Sami, Holl Anne-Catherine, Schizas Nikolaos V., Alekseev Victor

Oceanologia

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2019

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No. 61 (2)

227--238

EN

The invasion of exotic species into native ecosystems is becoming a crucial issue in global biology. Over the last ten years, at least 45 invasions of aquatic species have been reported in the eastern part of the Gulf of Finland; the majority of them were introduced through ballast water. Recently, invasion of the estuarine calanoid copepod Eurytemora carolleeae (Temoridae), originating from North America, has been reported in several European estuaries and particularly in the Gulf of Finland. This species is morphologically very similar to the native Eurytemora affinis, but it is easily discriminated by molecular markers. In this study, we monitored the distribution area of the invasive copepod species in European waters, as well as the population structure of (native) E. affinis and (invasive) E. carolleeae, from 2006 to 2018 in the Gulf of Finland. The population density of E. affinis was significantly higher, compared to E. carolleeae, during most of the study period. The only exception was Neva Bay in 2010, wherein the invasive species dominated possibly due to high temperatures and differences in the levels of fish predation. The reproductive performance of E. carolleeae was also higher than that of E. affinis. These results show different population dynamics between the two species. It was revealed that invasive E. carolleeae develops in some of the very same habitats as native E. affinis, thereby potentially becoming a significant component of the zooplankton in the studied area. Moreover, invader has the potential to displace native E. affinis.

5

Effects of environmental variables on midsummer dinoflagellate community in the Neva Estuary (Baltic Sea)

Golubkov Mikhail, Nikulina Vera, Golubkov Sergey

Oceanologia

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2019

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No. 61 (2)

197--207

EN

Dinoflagellates account for most of the harmful phytoplankton species but relatively little is known about the specific responses of different species to environmental variables. 21 dino-flagellate species were recorded in the plankton of the Neva Estuary since the mid-19th century. 14- year long data of midsummer dinoflagellate biomass was statistically analyzed in the Neva Estuary to show the changes in dinoflagellate species in relation to environmental factors. Biomasses of Dinophysis norvegica (Clapared & Lachmann 1859), Prorocentrum lima ((Ehrenberg) F.Stein 1878) and Peridinium aciculiferum (Lemmermann 1900) had very similar positive relationships with salinity, temperature, phosphorus and suspended particulate organic matter concentrations while the biomass of the other common species Peridinium cinctum ((Müller) Ehrenberg 1832) and Peridinium sp. mostly showed quite opposite trends. Climate fluctuations leading to changes in the environmental variables could significantly affect the composition and productivity of the dinoflagellate community. Biomass of Glenodinium sp. and Peridinium sp. positively correlated with primary production and biomass and chlorophyll a concentration, but did not show a positive relationship with phosphorus. This may be due to the fact that these species in the conditions of the Neva Estuary, apparently, are more consumers than producers of organic matter, feeding on algae and cyanobacteria of phytoplankton. Therefore, to interpret the relationships between the dinoflagellate biomass and environmental variables one should take into account that the species of this group is characterized by mixotrophy and, consequently, their biomass may depend not only on the conditions of autotrophic, but also heterotrophic nutrition.

6

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

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

Oceanologia

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2018

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No. 60 (1)

16--31

EN

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.

7

Case-Study Modelling Analysis of Hydrodynamics in the Nearshore of the Baltic Sea Forced by Extreme Along-shore Wind in the Case of a Cross-shore Obstacle

Sokolov A., Chubarenko B.

Archives of Hydro-Engineering and Environmental Mechanics

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2018

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Vol. 65, nr 3

163--176

EN

In the current study we use a three-dimensional model with hydrodynamic and spectral wave modules operating in a coupled mode to simulate the response of currents and wind wave fields to winds of 20–25 m/sec offshore of the protective structure of the Saint Petersburg Flood Prevention Facility Complex. The model was calibrated against field data, which allowed us to obtain a tool describing storm situations in the eastern part of the Gulf of Finland with a satisfactory accuracy. The numerical modeling showed that the protective dam did not have a noticeable effect on the levels of stormsurge, significantwave height, or current speed in areas seaward of the dam. The increase in erosion processes on the southern shore of the easternmost part of the Gulf of Finland in recent past has most probably been related to other factors. We found that if a west or south-west wind of at least 25 m/s blows over the Baltic Sea for at least 16 hours, the level of storm surges seaward of the dam may reach 3 or more meters. An artificial strengthening of the coastline and the creation of shore protection structures are recommended.

8

Bronka i inne porty Rosji nad Zatoką Fińską

Palmowski T.

Problemy Transportu i Logistyki

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2017

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nr 1 (37)

233--243

PL

Zgodnie z rosyjską strategią morską, Morze Bałtyckie jest najważniejszym szlakiem wymiany handlowej Rosji z państwami europejskimi. Modernizacja, rozbudowa i budowa nowych portów Rosji dotyczy głównie Sankt Petersburga i Zatoki Fińskiej. Wzrost możliwości przeładunkowych portów pozwoli na maksymalne zmniejszenie uzależnienia Federacji Rosyjskiej od przewozów tranzytowych. Przeładunki głównych portów rosyjskich w Zatoce Fińskiej stanowią ponad 85% całkowitych obrotów rosyjskich portów bałtyckich. Porty w Ust-Łudze i Primorsku w 2015 roku odnotowały największe obroty. W latach 2008–2015 przeładunki w Ust-Łudze wzrosły ponad 11-krotnie. Sankt Petersburg jest największym portem kontenerowym w regionie Morza Bałtyckiego. Port nie może się dalej rozwijać z uwagi na brak wolnych terenów. Jest to spowodowane bezpośrednim sąsiedztwem miasta Sankt-Petersburg. W końcu 2015 roku do grupy najnowszych portów kontenerowych i ro-ro dołączył port Bronka. Docelowo port ten ma stać się „główną bramą dla kontenerów płynących do Rosji”.

EN

According to the Russian maritime strategy, the Baltic Sea is for Russia the most important trading route to European countries. Modernisation, development and the construction of new ports in Russia concentrate in Sankt Petersburg and the Gulf of Finland. The growing cargo handling capacity of ports will lead to reducing the dependence of the Russian Federation on transit transport. Cargo volumes handled by main Russian ports in the Gulf of Finland constitute over 85% of the total turnover of Russian ports on the Baltic Sea. The ports in Ust-Luga and Primorsk noted their biggest turnover in 2015. In the years 2008-2015, cargo volumes in Ust-Luga rose eleven fold. Sankt Petersburg is the biggest container port in the Baltic Sea Region. The shortage of development areas, caused by the urban built-up of Sankt-Petersburg, has exhausted further port development. At the end of 2015, Bronka Port joined the group of the newest container and ro-ro ports. The port is to become the key gate for containers sailing to Russia.

9

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

Suhhova I., Pavelson J., Lagemaa P.

Oceanologia

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2015

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No. 57 (2)

132--143

EN

In our intraseasonal variability studies of currents in the coastal sea of the Gulf of Finland northeast of Pakri Peninsula, we compared the observation data from a bottom-mounted ADCP (March–June of 2009, 50 m depth) with the simulation data from High Resolution Operational Model of the Baltic (HIROMB). The structure of the current pattern appeared strongly dependent on the stratification conditions. The flow was quasi-barotropic during the periods of weak inverse thermal stratification at the end of winter season and at transition from the inverse thermal stratification to summer type stratification when the sea was thermally unstratified, but mostly two-layered (baroclinic) when the summer type thermal stratification had developed. The alternation of strong westward (eastward) currents (up to 30 cm s-1) in the upper layer is explained in terms of coastal upwelling (downwelling) due to favourable background winds. The measured and the modelled upper layers along isobath currents showed a noticeable correlation with the correlation coefficient of 0.52 and 0.82 during the periods of winter type and summer type stratifications, respectively, and the absence of a significant correlation during the transition period. The eastward (upwind) current episodes with speeds reaching 18 cm s-1 below the seasonal thermocline are likely to reflect the specific circulation response in the elongated basin caused by the easterly wind. The long-term mean (over 3.5 months) current vector (−2.0 cm s-1, −2.9 cm s-1) was westward in the upper sea and eastward, nearly along isobaths (1.1 cm s-1, −0.3 cm s-1) in the deeper layers.

10

Ship Route Design for Avoiding Heavy Weather and Sea Conditions

Cai Y., Wen Y., Wu L.

TransNav : International Journal on Marine Navigation and Safety of Sea Transportation

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2014

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Vol. 8 no. 4

551--556

EN

This paper covers the current state of maritime oil transportation in the Baltic Sea and the development of oil transportation in the 2000s, as well as estimations of transported oil volumes in 2020 and 2030 in the Gulf of Finland. The scenarios were formulated on the basis of a current state analysis, energy and transportation strategies and scenarios and expert assessments. The study showed that the volumes of oil transportation in the Gulf of Finland will increase only moderately compared to the current status: 9.5-33.8 %, depending on the scenario. Green energy policy favours renewable energy sources, which can be seen in the smaller volumes of transported oil in the 2030 scenarios compared to the 2020 scenarios. In the Slow development 2020 scenario, oil transport volumes for 2020 are expected to be 170.6 Mt (million tonnes), in the Average development 2020 187.1 Mt and in the Strong development 2020 201.5 Mt. The corresponding oil volumes for the 2030 scenarios were 165 Mt for the Stagnating development 2030 scenario, 177.5 Mt for the Towards a greener society 2030 scenario and 169.5 Mt in the Decarbonising society 2030 scenario.

11

Changes in Oil Transportation in the Years 2020 and 2030 – The Case of the Gulf of Finland

Brunila O., Storgård J.

TransNav : International Journal on Marine Navigation and Safety of Sea Transportation

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2014

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Vol. 8, no. 3

403--409

EN

This paper covers the current state of maritime oil transportation in the Baltic Sea and the development of oil transportation in the 2000s, as well as estimations of transported oil volumes in 2020 and 2030 in the Gulf of Finland. The scenarios were formulated on the basis of a current state analysis, energy and transportation strategies and scenarios and expert assessments. The study showed that the volumes of oil transportation in the Gulf of Finland will increase only moderately compared to the current status: 9.5-33.8 %, depending on the scenario. Green energy policy favours renewable energy sources, which can be seen in the smaller volumes of transported oil in the 2030 scenarios compared to the 2020 scenarios. In the Slow development 2020 scenario, oil transport volumes for 2020 are expected to be 170.6 Mt (million tonnes), in the Average development 2020 187.1 Mt and in the Strong development 2020 201.5 Mt. The corresponding oil volumes for the 2030 scenarios were 165 Mt for the Stagnating development 2030 scenario, 177.5 Mt for the Towards a greener society 2030 scenario and 169.5 Mt in the Decarbonising society 2030 scenario.

12

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

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

Oceanologia

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2014

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No. 56 (4)

737--756

EN

Validation of algorithms for the retrieval of concentrations of chlorophyll (Chl) and total suspended matter (TSM) in the Gulf of Finland from satellite ocean colour data was carried out using field measurement data from summer 2012 and 2013. These data included spectral values of the remote sensing reflectance Rrs(λ), Chl and TSM concentrations. Testing of the existing algorithms (OC4v4, OC3M, and the Baltic regional algorithms developed by Polish specialists) showed that all of them overestimated Chl several times. The new regional algorithms were developed on the basis of measured values of Rrs(λ), Chl and TSM (40 stations in total). Direct comparison of Chl and TSM values, obtained from MODIS-Aqua data with the algorithms developed here, with their in situ values showed reasonable agreement. The spatial distributions of Chl and TSM concentrations were constructed from MODIS-Aqua data. Errors of the atmospheric correction were analysed.

13

The effectiveness of maritime safety policy instruments from the Finnish maritime experts’ point of view – case Gulf of Finland and prevention of an oil accident

Lappalainen J., Storgård J., Tapaninen U.

TransNav : International Journal on Marine Navigation and Safety of Sea Transportation

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2013

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Vol. 7, no. 3

353--362

EN

Sea accidents are aimed to be prevented with an extensive amount of maritime safety regulation. The purpose of this paper is to present the findings of a questionnaire study that was targeted at Finnish maritime experts and addressed the question: how to prevent an oil accident in the Gulf of Finland. This study also includes a literature study about the problems of the current maritime safety regime. The findings of the questionnaire study are compared to the findings of the literature study. The questionnaire study showed that many kinds of policies have improved maritime safety, and they are needed to ensure maritime safety. For instance, ship construction, fairway maintenance, nautical charts and rules of the road at sea can be considered the cornerstones of maritime safety. However, the results ranked voluntary activities of companies as the most effective way to improve maritime safety in the future. Self-regulative approaches could solve some problems connected to more traditional policy-making.

14

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

Merkouriadi I., Leppäranta M.

Oceanologia

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2013

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No. 55 (1)

147-166

EN

The influence of landfast ice on hydrography and circulation is examined in Santala Bay, adjacent to the Hanko Peninsula, Gulf of Finland. Three-dimensional electromagnetic current meters and conductivity-temperature-depth (CTD) sensors were deployed in winters 1999-2000 and 2000-2001 during the Finnish-Japanese "Hanko 9012" experiment. In each winter, data collection started one month before the initial ice formation and lasted until one month after the ice had melted completely. Temperature and salinity are compared with long-term data from the Tvärminne Zoological Station, also located on the Hanko Peninsula. The water temperature was 2°C less than the long-term average. Ice formation and melting show up in the salinity evolution of the water body, which makes salinity a good indicator of ice formation and breakup in Santala Bay. The circulation under the ice became weaker by almost 1 cm s-1.

15

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

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

Oceanologia

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2013

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No. 55 (4)

837--857

EN

The degree of inter-annual variability in spring and summer phytoplankton blooms and nitrogen fixation in response to the deposition of oxidized nitrogen originating from ship emissions (hereafter nitrogen deposition) was evaluated in the Gulf of Finland (Baltic Sea) based on 10-year (1997-2006) simulation results using a coupled hydrodynamic (GETM) and ecological (ERGOM) model. Ship emissions were generated for 2008 using the Ship Traffic Emission Assessment Model, and ship nitrogen deposition was calculated using the Hilatar chemistry-transport model over the Baltic Sea. The annual ship nitrogen deposition in the Gulf of Finland was 1.6 kt N, about 12% of the annual atmospheric deposition, and increased in summer, up to 30% compared to the monthly atmospheric deposition. Ship nitrogen deposition caused an increase in spring and post-bloom primary production in two functional groups (diatoms and flagellates), at the same time reducing phosphate resources in the upper layer. Nitrogen fixation due to ship nitrogen deposition decreased by 1-1.6 kt N year-1 (2-6%). The effect of ship nitrogen deposition on nitrogen fixation was greater in the western and central Gulf of Finland. The additional ship nitrogen deposition to the Gulf was practically compensated for by a decrease in nitrogen fixation.

16

Simplified Risk Analysis of Tanker Collisions in the Gulf of Finland

Goerlandt F., Hanninen M., Stahlberg K., Montewka J., Kujala P.

TransNav : International Journal on Marine Navigation and Safety of Sea Transportation

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2012

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Vol. 6, no. 3

381--387

EN

Maritime traffic poses various risks in terms of human casualties, environmental pollution or loss of property. In particular, tankers pose a high environmental risk as they carry very large amounts of oil or more modest amounts of possibly highly toxic chemicals. In this paper, a simplified risk assessment meth-odology for spills from tankers is proposed for the Gulf of Finland, for tankers involved in a ship-ship collision. The method is placed in a wider risk assessment methodology, inspired by the Formal Safety Assess-ment (FSA) and determines the risk as a combination of probability of occurrence and severity of the consequences. The collision probability model is based on a time-domain micro simulation of maritime traf-fic, for which the input is obtained through a detailed analysis of data from the Automatic Identification System (AIS). In addition, an accident causation model, coupled to the output of the traffic simulation model is proposed to evaluate the risk reduction effect of the risk control options. Further development of the model is needed, but the modular nature of the model allows for continuous improvement of the modules and the ex-tension of the model to include more hazards or consequences, such that the effect of risk control options can be studied and recommendations made. This paper shows some preliminary results of some risk analysis blocks for tanker collisions in the Gulf of Finland.

17

Estimating the Number of Tanker Collisions in the Gulf of Finland in 2015

Hanninen P., Kujala P., Ylitalo J., Kuronen J.

TransNav : International Journal on Marine Navigation and Safety of Sea Transportation

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2012

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Vol. 6, no. 3

367--373

EN

The paper presents a model for estimating the number of ship-ship collisions for future traffic scenarios. The modeling is based on an approach where the number of collisions in an area is estimated as a product of the number collision candidates, i.e. the number of collisions of two ships, if no evasive maneuvers were made, and a causation probability describing the probability of making no evasive maneuvers. However, the number of collisions is presented as a combination of binomially distributed random variables. The model is applied for the assessment of tanker collision frequency in the Gulf of Finland in 2015. 2015 traffic is modeled as three alternative scenarios each having a certain probability of occurrence. The number of collisions can be presented either for each scenario, or as an estimate including the uncertainty in future marine traffic development by taking into account all scenarios and their occurrence probabilities.

18

A Decision Support Tool for VTS Centers to Detect Grounding Candidates

Mazaheri A., Goerlandt F., Kujala P., Montewka J.

TransNav : International Journal on Marine Navigation and Safety of Sea Transportation

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2012

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Vol. 6, no. 3

337--343

EN

AIS (Automatic Identification System) data analysis is used to define ship domain for ground-ing scenarios. The domain has been divided into two areas as inner and outer domains. Inner domain has clear border, which is based on ship dynamic characteristics. Violation of inner domain makes the grounding acci-dent unavoidable. Outer domain area is defined with AIS data analyzing. Outer domain shows the situation of own ship in compare with other similar ships that previously were in the same situation. The domain can be used as a decision support tool in VTS (Vessel Traffic Service) centers to detect grounding candidate vessels. In the case study presented in this paper, one type of ship, which is tanker, in a waterway to Sköldvik in the Gulf of Finland is taken into account.

19

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

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

Oceanologia

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2012

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No. 54 (3)

395-419

EN

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.

20

The role of the spatial resolution of a three-dimensional hydrodynamic model for marine transport risk assessment

Andrejev O., Soomere T., Sokolov A., Myrberg K.

Oceanologia

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2011

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No. 53 (1-TI)

309-334

EN

The paper addresses the sensitivity of a novel method for quantifying the environmental risks associated with the current-driven transport of adverse impacts released from offshore sources (e.g. ship traffic) with respect to the spatial resolution of the underlying hydrodynamic model. The risk is evaluated as the probability of particles released in different sea areas hitting the coast and in terms of the time after which the hit occurs (particle age) on the basis of a statistical analysis of large sets of 10-day long Lagrangian trajectories calculated for 1987-1991 for the Gulf of Finland, the Baltic Sea. The relevant 2D maps are calculated using the OAAS model with spatial resolutions of 2, 1 and 0.5 nautical miles (nm) and with identical initial, boundary and forcing conditions from the Rossby Centre 3D hydrodynamic model (RCO, Swedish Meteorological and Hydrological Institute). The spatially averaged values of the probability and particle age display hardly any dependence on the resolution. They both reach almost identical stationary levels (0.67-0.69 and ca 5.3 days respectively) after a few years of simulations. Also, the spatial distributions of the relevant fields are qualitatively similar for all resolutions. In contrast, the optimum locations for fairways depend substantially on the resolution, whereas the results for the 2 nm model differ considerably from those obtained using finer-resolution models. It is concluded that eddy-permitting models with a grid step exceeding half the local baroclinic Rossby radius are suitable for a quick check of whether or not any potential gain from this method is feasible, whereas higher-resolution simulations with eddy-resolving models are necessary for detailed planning. The asymptotic values of the average probability and particle age are suggested as an indicator of the potential gain from the method in question and also as a new measure of the vulnerability of the nearshore of water bodies to offshore traffic accidents.