Ülo Suursaar

• PhD
• Associate Professor at University of Tartu

In order to estimate the possible parameters of future extreme extratropical cyclones (ETCs), a pseudo-climate modelling study of three historical storms originating from the Atlantic Ocean and one from the Black Sea area was performed using multi-model approach considering IPCC emission scenarios RCP4.5 and RCP8.5 for the twenty-first century. App...

Traditionally, upwelling-related studies in the Baltic Sea have been limited to the period from May to September. Based on wintertime in situ measurements at two nearshore locations in the Gulf of Finland, clear evidence of winter “warm” upwelling events was detected and analysed. The process was very common. At a 10 m deep location, upwelling caus...

The summer 2021 heat waves (HWs) and marine heat waves (MHWs) were analysed on the basis of air and water temperatures measured both in the open part of the Gulf of Finland at buoys and lighthouses and some land-based stations. The summer of 2021 (June, July, August) was the hottest on record in Estonia with distinct HW episodes around 18–23 June...

Holocene relative sea level changes and palaeogeography of the uplifting Tihu ridge-swale beach system in the functionally tideless Baltic Sea were reconstructed using airborne LiDAR elevation data, ground-penetrating radar surveys, sedimentological proxies, recent models of Fennoscandian uplift due to glacial isostatic adjustment, and GIS-based te...

This study aims to reconstruct the changes in storminess during the past 7600 years in the northeastern Baltic Sea region. For storminess reconstructions, aeolian sand influx (ASI) in coastal peat bog deposits was applied as an indicator of the past storminess. We analyzed cores from four peat bogs in the western and northern coastal areas of Eston...

Tõnisson H., Kont A., Suursaar Ü., Jaagus J., Rivis R. & Buynevich I. 2024: Morphosedimentary evolution of Estonian coastline: role of climatic and hydrodynamic forcing over the past decades. Boreal Env. Res. 29: 103-125. Decadal trends in regional climate are investigated for their possible influence on the shoreline changes at a number of Baltic...

Most barrier coasts of the world are characterized by tidal processes, which are especially important in maintaining tidal inlets and backbarrier wetlands. However, in many semi-enclosed or isolated sea basins (Baltic et al.), tidal component has minimal or no influence and are functionally non-tidal. In recent decades, the use of ground-penetratin...

A combination of the complicated shape of the Baltic Sea and the presence of a bi-directional system of strong winds in large parts of this water body leads to greatly different properties of wave climate in its different sub-basins. These features also give rise to substantial variations in the response of wave properties to the changing climate....

We calculated two sets of idealised ice-free wave hindcast data on a high-resolution, three-layer nested grid covering the Baltic Sea, using two different wind datasets (ERA5 and BaltAn65+), to evaluate the performance of the model in the open and sheltered parts of the sea. The highest resolution of the grids is 260 m. The outcome of simulations i...

A diverse suite of erosional features along the shoreline of Lehtma (Hiiumaa Island, Estonia) is used to assess their morphodynamic context and preservation potential. The Holocene strandplain along the eastfacing (leeward) shoreline has experienced rapid retreat due to the anthropogenically induced sediment deficit. The study site is located just...

Coastal strandplains on Saaremaa Island, Estonia, contain a rich archive of past events, which are recorded as geomorphic and lithological indicators of reworking (erosional) and depositional (accretionary) phases. This study presents a new dataset of low-field bulk magnetic susceptibility (MS) values from coastal sands as a rapid means of characte...

This chapter provides a concise overview of the entire monograph by assembling summaries of 10 individual chapters starting with a global review of large-scale, persistent nutrient fronts of the World Ocean followed by regional chapters on the Arctic Ocean, North Atlantic, Baltic Sea, Kuroshio Current, and the Yellow Sea, a global review of CDOM dy...

Oceanic fronts have a crucial impact on the physical, chemical, and biological processes of the Baltic Sea. Due to its complex morphometry and numerous freshwater inflows, the Baltic Sea hosts a multitude of fronts that separate water masses with different properties. Intense thermohaline and nutrient fronts occur as high-gradient zones in the Balt...

The aim of the study was to analyse the sequence of winter ("warm") upwelling and lake-effect snow (LES) events that deposited up to 50 cm of snow along the North Estonian coast in January-February 2021. Based on weather and aerological data, four episodes of LES were documented. Heavy, localized lake-effect enhanced precipitation occurred along a...

Multi-mission satellite altimetry (e.g., ERS, Envisat, TOPEX/Poseidon, Jason) data have enabled a synoptic-scale view of ocean variations in past decades. Since 2016, the Sentinel-3 mission has provided better spatial and temporal sampling compared to its predecessors. The Sentinel-3 Ku/C Radar Altimeter (SRAL) is one of the synthetic aperture rada...

Multimission satellite altimetry (e.g. ERS, Envisat, TOPEX/Poseidon, Jason) data have enabled a synoptic view of ocean variations in the past decades, including sea-level rise and mesoscale circulations. Since 2016, the Sentinel-3 mission has provided better spatial and temporal sampling compared with its predecessors. The Sentinel-3 Ku/C Radar Alt...

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 weathe...

The ongoing climate change is expected to affect the distribution and vitality of marine aquatic species through various links and changes in environmental conditions. The aim of the study was to analyse and compare climate change related effects on native and non-native benthic species groups in the Baltic Sea. We analysed the impact of changes on...

Tõnisson, H., Suursaar, Ü., Rivis, R., Tamura, T., Aarna, T., Vilumaa, K., and Kont, A., 2020. Characteristics and formation of a solitary dune belt encountered along the coast of Estonia. Dunes are not particularly high and widespread on practically tideless, prograding coasts of Estonia. The aim of the study was to document characteristics of a s...

Paalme, T.; Torn, K.; Martin, G.; Kotta, I., and Suursaar, Ü., 2020. Littoral benthic communities under effect of heat wave and upwelling events in NE Baltic Sea. In: Malvárez, G. and Navas, F. (eds.), Global Coastal Issues of 2020. Journal of Coastal Research, Special Issue No. 95, pp. 133-137. Coconut Creek (Florida), ISSN 0749-0208. The Baltic S...

The current study focuses on trends in hydrophysical and -chemical parameters (e.g. temperature, salinity, dissolved oxygen, chlorophyll a (Chl a), pH and nutrients) in the Estonian coastal sea and offshore areas in relation to the biogeochemical processes and marine carbon dioxide system of the Baltic Sea. Analysis of 586 time series of these para...

Due to changes in atmospheric circulation and warmer winters, the frequency of strong westerly storms associated with high sea level in ice-free sea conditions has increased on the western coast of Estonia. This trend is especially dangerous for the sections of depositional seashores along the eastern coast of the Baltic Sea such as Pärnu Bay and i...

2D sea level trend and variability fields of the Baltic Sea were reconstructed based on statistical modeling of monthly tide gauge observations, and model reanalysis as a reference. The reconstruction included both absolute and relative sea level (RSL) in 11 km resolution over the period 1900–2014. The reconstructed monthly sea level had an average...

The potential response of occurrence of charophyte and angiosperm communities to climate change in the brackish environment of the Baltic Sea was investigated using the boosted regression trees (BRT) modelling method. The aim of the study was to analyse sensitivity of various species to climate change and to predict the changes in species’ distribu...

Recent LiDAR surveys have revealed that on postglacially uplifting coasts of Estonia rhythmic coastal landforms (beach ridge sequences and foredune plains) occur to a considerable extent. We studied four of them to reveal age and periodicity in these multiple ridge systems and discussed their genesis in the Subatlantic (semi‐continental) conditions...

Coastal zone is among the most vulnerable areas of the Earth to global warming, firstly, due to anticipated mean sea level rise, and secondly, regarding changes in storm activity. In Europe, much of the high-impact weather events are associated with extratropical cyclones (ETC). It is highly possible that tropical cyclones will get stronger under f...

Climate change in recent decades has been identified as a significant threat to natural environments and human wellbeing. This is because some of the contemporary changes to climate are abrupt and result in persistent changes in the state of natural systems; so called regime shifts (RS). This study aimed to detect and analyse the timing and strengt...

List of used time series, their original temporal resolution and spatial extent. Below potted history for each variable with identified regime shifts as broken lines. Number at the broken line reflects the statistical significance of the particular regime shift. (PDF)

A R script on how to depict a timing and relative strength of statistically significant RSs and the relatedness of time series within each system category (i.e. abiotic and biotic elements of atmospheric, terrestrial, bog, lake, river and marine systems) in terms of the timing of RSs. (PDF)

Palginõmm, V.; Orviku, K.; Suursaar, Ü.; Kont, A.; Tõnisson, H., and Rivis, R., 2018. Lessons Learned from Record-High Storm Surges and Associated Inundations in Pärnu, SW Estonia. In: Shim, J.-S.; Chun, I., and Lim, H.S. (eds.), Proceedings from the International Coastal Symposium (ICS) 2018 (Busan, Republic of Korea). Journal of Coastal Research,...

Suursaar, Ü.; Sepp, M.; Post, P., and Mäll, M., 2018. An inventory of historic storms and cyclone tracks that have caused met-ocean and coastal risks in the eastern Baltic Sea. In: Shim, J.-S.; Chun, I., and Lim, H.S. (eds.), Proceedings from the International Coastal Symposium (ICS) 2018 (Busan, Republic of Korea). Journal of Coastal Research, Spe...

Variations in Estonian sea level records (1842–2016) are interpreted using harmonic and sliding window trend analysis together with the latest findings on the crustal movements in the region of the Baltic Sea. Considering the most recent relative-to-geoid land uplift (LU) rates from the semiempirical LU model NKG2016LU_lev, it was possible, probabl...

Weather Research and Forecasting atmosphere model and Finite Volume Community Ocean Model were for the first time used under the pseudo-climate simulation approach, to study the parameters of an extreme storm in the Baltic Sea area. We reconstructed the met-ocean conditions during the historical storm Gudrun (which caused a record-high +275 cm surg...

Buried or elevated coastal ridges may serve as archives of past variations in sea level and climate conditions. Sometimes such ridges or coastal scarps appear in patterns, particularly on uplifting coasts with adequate sediment supply. Along the seacoasts of Estonia, where relative-to-geoid postglacial uplift can vary between 1.7 and 3.4 mm/yr, at...

Establishment of distinct circulation patterns in the Gulf of Finland was observed by a targeted measurement campaign in winter 2013–2014. Strong and long enough up-estuary wind events caused a collapse of vertical stratification and development of a barotropic flow system consisting of an outflow in the open part and inflow along the coasts. In th...

Tõnisson, H.; Suursaar, Ü.; Alari, V.; Muru, M.; Rivis, R.; Kont, A.; and Viitak, M., 2016. Measurement and model simulations of hydrodynamic parameters, observations of coastal changes and experiments with indicator sediments to analyse the impact of storm St. Jude in October, 2013. In: Vila-Concejo, A.; Bruce, E.; Kennedy, D.M., and McCarroll, R....

Despite improving navigation safety measures, there is a growing risk of accidental oil spills and associated oil pollution on the Baltic Sea, an area which has been designated by a Particularly Sensitive Sea Area by the International Maritime Organization. Environmental Sensitivity Index (ESI) maps have been an integral component of oil-spill cont...

A third generation numerical wave model SWAN (Simulating WAves Nearshore) was applied to study the spatio-temporal effect of surface currents and sea level height on significant wave height; and to describe the mechanisms responsible for wave–current interaction in the eastern Baltic Sea. Simulation results were validated by comparison with in situ...

Wave forcing is an important hydrodynamic variable that influences spatial patterns and temporal dynamics of marine benthos. In this study, we used three principally different wave models – simplified wave model (SWM), spectral wave model SWAN (simulating waves nearshore), and locally calibrated point model (LCPM) – to assess the effects of wave fo...

The EU Marine Strategy Framework Directive (MSFD) requires assessment of environmental status in relation to changing human pressures. In this study taxonomic composition of beach wrack is proposed as an indicator for the assessment of coastal sea benthic macrovegetation biodiversity within the context of the MSFD. Based on the relationships betwee...

A case study based on the January 2005 storm Gudrun parameters has shown a good agreement between observations and results obtained from atmospheric and ocean models. In the methodology we used for simulating “future storm Gudrun”, no increase in the intensity of this particular future storm was found but instead, a slight decrease was noticed. Whe...

Statistics of hindcast wave series were studied at eight differently exposed fetch-limited Estonian coastal sea locations (Harilaid, Kihnu, Kõiguste, Matsi, Neugrund, Sundgrund, Suurupi and Letipea). Based on episodic wave measurements obtained with the bottom mounted Recording Doppler Current Profiler in 2006–2014, a model for significant wave hei...

This chapter describes observed changes in sea level and wind waves in the Baltic Sea basin over the past 200 years and the main climate drivers of this change. The datasets available for studying these are described in detail. Recent climate change and land uplift are causing changes in sea level. Relative sea level is falling by 8.2 mm year−1 in...

The aim of the study was to investigate hydrodynamic effects on the formation of beach wrack at three locations in the northern Baltic Sea and to quantify the differences between the composition of species found in the beach wrack and in the neighbouring sea. Hydrodynamic measurements and modelling indicated that the beach wrack was mostly of local...

The paper discusses various aspects of local and regional storminess, as well as challenges in quantifying its tendencies in the eastern section of the Baltic Sea. The study is based on various long-term data sets, such as wind and sea level observation data from coastal stations and tide gauges of Estonia (1899–2013). It also discusses long-term w...

The current study was focusing on the shore processes and the coastal sea fronting Sillamäe town. The shores near the Sillamäe starting west from the Voka settlement and ending at the top of Cape Kannuka were described as one litho dynamic system with a good natural balance in the recent past. The main aim of the paper was to analyse the impact of...

Temporal variations of shoreline changes have been analyzed and interpreted in three differently exposed Estonian coastal sections. Using coastline contours that have been recorded frequently over the last twelve years, as well as recently digitized aerial photographs, orthophotos and old topographic maps (some of them daring back to 1900), all ove...

Oil transportation is growing in the Baltic Sea area and especially in the Gulf of Finland where it will reach approximately 180-200 million tons a year by 2020. Growing oil transportation is considerably contributing to the risk of accidental spill-related shoreline oiling. This paper focuses on amending the Environmental Sensitivity Index (ESI) r...

Our current understanding of the morphodynamics in swash and surf zones is limited due to their turbulent and irregular nature. The importance of this zone to sediment transport led us to perform a sophisticated field experiment using painted sediments. Sediments collected locally from beach ridges were sorted into the following diameters: 1-2.5 cm...

Oil transportation is growing in the Baltic Sea area and especially in the Gulf of Finland where it is reaching approximately 180-200 million tons a year by 2020. Growing oil transportation is considerably contributing to the risk of accidental spill related shoreline oiling. This paper focuses on amending the Environmental Sensitivity Index (ESI)...

The national communication describes Estonia´s vulnerability and the actions taken with regard to adapting to climate change. https://unfccc.int/files/national_reports/non-annex_i_natcom/application/pdf/est_nc6.pdf.

Analysis of relationships between near-shore hydrodynamics and sediment movement on Osmussaar Island, western Estonia Based on field studies, hydro-meteorological data and wave hindcasts, coastal developments and their hydrodynamic forcing conditions are studied on the limestone relict island of Osmussaar. Areal growth of Osmussaar Island, which em...

Variations and trends in storminess (number of storm days), and mean and maximum sea levels were analysed along the Estonian coast during the last century. An increase in storminess was detected at the Vilsandi and Sõrve stations, although inhomogeneities in the wind data make the trends less reliable. Mean sea level trends depend on the post-glaci...

At International Maritime Organization's (IMO) Marine Environment Protection Committee's 53rd session in July 2005, the Baltic Sea was designated as a Particularly Sensitive Sea Area (PSSA). At the same time the oil transportation is growing significantly in the Baltic Sea area and especially in the Gulf of Finland exceeding 250 million tons a year...

Wave parameters were studied in four differently exposed fetch-limited Estonian coastal sea locations: the Harilaid Peninsula facing W–NW, Letipea N–NE, Matsi SW and Kõiguste SE. Based on high-quality measurements of waves with the bottom-mounted Recording Doppler Current Profiler in 2006–2011, a model for significant wave height was calibrated sep...

The paper presents a study of currents and sea level variations in the nearly tideless sub-basins of the Baltic Sea, the Gulf of Riga and the West Estonian Archipelago Sea, using a high-resolution (of order 1 km grid) shallow sea hydrodynamic model. The model was forced by the measured wind and sea level data obtained from the data-base of the Esto...

The study analyzes the meteorological parameters, hydrodynamic conditions and coastal changes at three practically tideless locations on Saaremaa Island caused by storm Ulli (sustained wind speed 20 m/s, gusts 28 m/s) which struck the Estonian coast on 4 January 2012. It was the last and the most influential storm of a series of storms which began...

Changes in the natural and settlement history of Osmussaar Island are studied on the basis of hydrodynamic and geomorphic field experiments, as well as on old maps, archive material and ethnographic literature. Osmussaar is a 5 km long and 8 m high island which emerged from the Baltic Sea about 3000 years ago as a result of postglacial rebound. At...

Above Northern Europe, recent climate change manifests as shifts in wind climatology and storminess, which, in turn, influence hydrodynamic and underwater light regimes of the sea. The study is based on measurement of waves and currents obtained over the period of about 750 days, meteorological and sea level data from the Estonian weather and tide...

Based on measurements of waves and currents obtained for a period of 302 days with a bottom-mounted RDCP (Recording Doppler Current Profiler) at two differently exposed locations, a model for significant wave height was calibrated separately for those locations; in addition, the Gulf of Riga-Vainameri 21) model was validated, and the hydrodynamic c...

The study is analyzing the meteorological parameters, hydrodynamic conditions and coastal changes caused by extreme storm known as Berit, which travelled across the Baltic Sea from 27th to 29th of November in 2011. Wind speed on West Estonian islands reached to 19,7 m/s (gusts 29 m/s), 20,4 m/s on the northern coast (gusts 27 m/s) and 15 m/s (gusts...

The study is focused on a gravel-pebble spit in Kelba. It is a dynamic region in the magnitude and velocity of hydrodynamic and shore processes, where historical changes in shoreline position reflect the changes in wind and wave climate. The region has probably the roughest wave climate along the Estonian coast. In order to assess the changes in sh...

Osmussaar is a 5 km long relict island of the Baltic Clint, overlain by Quaternary deposits, which emerged from the Baltic Sea 3000 years ago as a result of postglacial rebound. An Ordovician limestone cliff 7m high is the most characteristic feature on the northern part of the island, whereas 2-3m high gravel-pebble ridges cover the southern part...

This paper discusses possible solutions to the problem of integrating fishery management into the process of Maritime Spatial Planning (MSP) and exemplifies the issue by analyzing the potential solution for the place based management of the Gulf of Riga herring fishery in the Parnu Bay (Baltic Sea). According to the latest scientific advice, the to...

Above Northern Europe, recent climate change, apart from temperature rise, also manifests as shifts in wind climatology and storminess, which, in turn, influences the marine ecosystem via changes in hydrodynamic regime. Based on meteorological and sea level data from the Estonian weather and tide gauge stations, as well as on hydrodynamic modelling...

The aim of the paper is to present statistical analysis of the sea level data obtained from the Estonian coastal tide gauges over the period 1842–2009, to assess storm surge risks and to discuss climate change related mitigation and management issues in the coastal zone of Estonia. Long-term variations of both mean and extreme sea level values were...

Over the last hundred years, the annual maximum ice extent in the Baltic Sea has varied between 12 and 100% of the surface area of the sea, and the number of days with ice has fluctuated between zero and about 160 along the Estonian coast of the Gulf of Finland. Apparently, variations in ice conditions have a strong and diverse influence on hydrody...

The aim of the paper is to investigate hydrodynamic conditions in the Neugrund Bank area from ADCP measurements in 2009-2010, to present a local long-term wave hindcast and to study coastal formations around the Neugrund. Coastal geomorphic surveys have been carried out since 2004 and analysis has been performed of aerial photographs and old charts...