Articles | Volume 19, issue 8
https://doi.org/10.5194/amt-19-2763-2026
© Author(s) 2026. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/amt-19-2763-2026
© Author(s) 2026. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
23 Apr 2026
Research article |
| 23 Apr 2026
| 23 Apr 2026
Studying anomalous propagation over marine areas using an experimental AIS receiver set-up
Finnish Meteorological Institute, Erik Palménin Aukio 1, Helsinki, Finland
Milla M. Johansson
Finnish Meteorological Institute, Erik Palménin Aukio 1, Helsinki, Finland
Mikko Lensu
Finnish Meteorological Institute, Erik Palménin Aukio 1, Helsinki, Finland
Jani Tyynelä
Finnish Meteorological Institute, Erik Palménin Aukio 1, Helsinki, Finland
Jukka-Pekka Jalkanen
Finnish Meteorological Institute, Erik Palménin Aukio 1, Helsinki, Finland
Mikael Hasu
Finnish Meteorological Institute, Erik Palménin Aukio 1, Helsinki, Finland
Ken Stenbäck
Finnish Meteorological Institute, Erik Palménin Aukio 1, Helsinki, Finland
Harry Lonka
Finnish Meteorological Institute, Erik Palménin Aukio 1, Helsinki, Finland
Lauri Laakso
Finnish Meteorological Institute, Erik Palménin Aukio 1, Helsinki, Finland
Atmospheric Chemistry Research Group, Chemical Resource Beneficiation, North-West University, Potchefstroom, South Africa
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Matias Uusinoka, Jari Haapala, Jan Åström, Mikko Lensu, and Arttu Polojärvi
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We tracked sea ice deformation over a nine-month period using high-resolution ship radar data and a state-of-the-art deep learning technique. We observe that the typically consistent scale-invariant pattern in sea ice deformation has a possible lower limit of about 102 meters in winter, but this behavior disappears during summer. Our findings provide important insights for considering current modeling assumptions and for connecting the scales of interest in sea ice dynamics.
Aino Ovaska, Elio Rauth, Daniel Holmberg, Paulo Artaxo, John Backman, Benjamin Bergmans, Don Collins, Marco Aurélio Franco, Shahzad Gani, Roy M. Harrison, Rakesh K. Hooda, Tareq Hussein, Antti-Pekka Hyvärinen, Kerneels Jaars, Adam Kristensson, Markku Kulmala, Lauri Laakso, Ari Laaksonen, Nikolaos Mihalopoulos, Colin O'Dowd, Jakub Ondracek, Tuukka Petäjä, Kristina Plauškaitė, Mira Pöhlker, Ximeng Qi, Peter Tunved, Ville Vakkari, Alfred Wiedensohler, Kai Puolamäki, Tuomo Nieminen, Veli-Matti Kerminen, Victoria A. Sinclair, and Pauli Paasonen
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Kristiina Verro, Cecilia Äijälä, Roberta Pirazzini, Ruzica Dadic, Damien Maure, Willem Jan van de Berg, Giacomo Traversa, Christiaan T. van Dalum, Petteri Uotila, Xavier Fettweis, Biagio Di Mauro, and Milla Johansson
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Hedi Kanarik, Laura Tuomi, Pekka Alenius, Elina Miettunen, Milla Johansson, Tuomo Roine, Antti Westerlund, and Kimmo K. Kahma
Ocean Sci., 21, 2125–2147, https://doi.org/10.5194/os-21-2125-2025, https://doi.org/10.5194/os-21-2125-2025, 2025
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The Archipelago Sea (AS), part of the Baltic Sea off the northwest coast of Finland, is a fragmented area with intense human activity. This study presents an overview of the observed currents and their main drivers in the area. While local winds primarily drive the AS currents, simultaneous sea level variations in the Bay of Bothnia and Gulf of Finland also significantly impact the area's dynamics.
Laura Tuomi, Milla Johansson, Andrew Twelves, Mika Rantanen, Priidik Lagemaa, Hedi Kanarik, Jani Särkkä, Urmas Raudsepp, and Antti Westerlund
State Planet Discuss., https://doi.org/10.5194/sp-2025-12, https://doi.org/10.5194/sp-2025-12, 2025
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A record low sea level of -153 cm, 34 cm below the previous minimum, was measured in the Bothnian Bay in November 2024. This extreme event was caused by a strong and long-lasting windstorm that followed an unusual track. The BAL MFC NRT physical forecast system was able to accurately predict this sea level event 3–4 days in advance. However, forecasts with longer lead times failed to predict the record low sea level, although they did indicate a significant drop in sea levels during the storm.
Androniki Maragkidou, Tiia Grönholm, Laura Rautiainen, Juha Nikmo, Jukka-Pekka Jalkanen, Timo Mäkelä, Timo Anttila, Lauri Laakso, and Jaakko Kukkonen
Atmos. Chem. Phys., 25, 2443–2457, https://doi.org/10.5194/acp-25-2443-2025, https://doi.org/10.5194/acp-25-2443-2025, 2025
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Martti Honkanen, Mika Aurela, Juha Hatakka, Lumi Haraguchi, Sami Kielosto, Timo Mäkelä, Jukka Seppälä, Simo-Matti Siiriä, Ken Stenbäck, Juha-Pekka Tuovinen, Pasi Ylöstalo, and Lauri Laakso
Biogeosciences, 21, 4341–4359, https://doi.org/10.5194/bg-21-4341-2024, https://doi.org/10.5194/bg-21-4341-2024, 2024
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Piers M. Forster, Chris Smith, Tristram Walsh, William F. Lamb, Robin Lamboll, Bradley Hall, Mathias Hauser, Aurélien Ribes, Debbie Rosen, Nathan P. Gillett, Matthew D. Palmer, Joeri Rogelj, Karina von Schuckmann, Blair Trewin, Myles Allen, Robbie Andrew, Richard A. Betts, Alex Borger, Tim Boyer, Jiddu A. Broersma, Carlo Buontempo, Samantha Burgess, Chiara Cagnazzo, Lijing Cheng, Pierre Friedlingstein, Andrew Gettelman, Johannes Gütschow, Masayoshi Ishii, Stuart Jenkins, Xin Lan, Colin Morice, Jens Mühle, Christopher Kadow, John Kennedy, Rachel E. Killick, Paul B. Krummel, Jan C. Minx, Gunnar Myhre, Vaishali Naik, Glen P. Peters, Anna Pirani, Julia Pongratz, Carl-Friedrich Schleussner, Sonia I. Seneviratne, Sophie Szopa, Peter Thorne, Mahesh V. M. Kovilakam, Elisa Majamäki, Jukka-Pekka Jalkanen, Margreet van Marle, Rachel M. Hoesly, Robert Rohde, Dominik Schumacher, Guido van der Werf, Russell Vose, Kirsten Zickfeld, Xuebin Zhang, Valérie Masson-Delmotte, and Panmao Zhai
Earth Syst. Sci. Data, 16, 2625–2658, https://doi.org/10.5194/essd-16-2625-2024, https://doi.org/10.5194/essd-16-2625-2024, 2024
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This paper tracks some key indicators of global warming through time, from 1850 through to the end of 2023. It is designed to give an authoritative estimate of global warming to date and its causes. We find that in 2023, global warming reached 1.3 °C and is increasing at over 0.2 °C per decade. This is caused by all-time-high greenhouse gas emissions.
Antonin Soulie, Claire Granier, Sabine Darras, Nicolas Zilbermann, Thierno Doumbia, Marc Guevara, Jukka-Pekka Jalkanen, Sekou Keita, Cathy Liousse, Monica Crippa, Diego Guizzardi, Rachel Hoesly, and Steven J. Smith
Earth Syst. Sci. Data, 16, 2261–2279, https://doi.org/10.5194/essd-16-2261-2024, https://doi.org/10.5194/essd-16-2261-2024, 2024
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Heidi Hellén, Rostislav Kouznetsov, Kaisa Kraft, Jukka Seppälä, Mika Vestenius, Jukka-Pekka Jalkanen, Lauri Laakso, and Hannele Hakola
Atmos. Chem. Phys., 24, 4717–4731, https://doi.org/10.5194/acp-24-4717-2024, https://doi.org/10.5194/acp-24-4717-2024, 2024
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Mixing ratios of C2-C5 NMHCs and methanethiol were measured on an island in the Baltic Sea using an in situ gas chromatograph. Shipping emissions were found to be an important source of ethene, ethyne, propene, and benzene. High summertime mixing ratios of methanethiol and dependence of mixing ratios on seawater temperature and height indicated the biogenic origin to possibly be phytoplankton or macroalgae. These emissions may have a strong impact on SO2 production and new particle formation.
Ville-Veikko Paunu, Niko Karvosenoja, David Segersson, Susana López-Aparicio, Ole-Kenneth Nielsen, Marlene Schmidt Plejdrup, Throstur Thorsteinsson, Dam Thanh Vo, Jeroen Kuenen, Hugo Denier van der Gon, Jukka-Pekka Jalkanen, Jørgen Brandt, and Camilla Geels
Earth Syst. Sci. Data, 16, 1453–1474, https://doi.org/10.5194/essd-16-1453-2024, https://doi.org/10.5194/essd-16-1453-2024, 2024
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Air pollution is an important cause of adverse health effects, even in Nordic countries. To assess their health impacts, emission inventories with high spatial resolution are needed. We studied how national data and methods for the spatial distribution of the emissions compare to a European level inventory. For road transport the methods are well established, but for machinery and off-road emissions the current recommendations for the spatial distribution of these emissions should be improved.
Peter Manshausen, Duncan Watson-Parris, Matthew W. Christensen, Jukka-Pekka Jalkanen, and Philip Stier
Atmos. Chem. Phys., 23, 12545–12555, https://doi.org/10.5194/acp-23-12545-2023, https://doi.org/10.5194/acp-23-12545-2023, 2023
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Aerosol from burning fuel changes cloud properties, e.g., the number of droplets and the content of water. Here, we study how clouds respond to different amounts of shipping aerosol. Droplet numbers increase linearly with increasing aerosol over a broad range until they stop increasing, while the amount of liquid water always increases, independently of emission amount. These changes in cloud properties can make them reflect more or less sunlight, which is important for the earth's climate.
Lea Fink, Matthias Karl, Volker Matthias, Sonia Oppo, Richard Kranenburg, Jeroen Kuenen, Sara Jutterström, Jana Moldanova, Elisa Majamäki, and Jukka-Pekka Jalkanen
Atmos. Chem. Phys., 23, 10163–10189, https://doi.org/10.5194/acp-23-10163-2023, https://doi.org/10.5194/acp-23-10163-2023, 2023
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The Mediterranean Sea is a heavily trafficked shipping area, and air quality monitoring stations in numerous cities along the Mediterranean coast have detected high levels of air pollutants originating from shipping emissions. The current study investigates how existing restrictions on shipping-related emissions to the atmosphere ensure compliance with legislation. Focus was laid on fine particles and particle species, which were simulated with five different chemical transport models.
Olle Räty, Marko Laine, Ulpu Leijala, Jani Särkkä, and Milla M. Johansson
Nat. Hazards Earth Syst. Sci., 23, 2403–2418, https://doi.org/10.5194/nhess-23-2403-2023, https://doi.org/10.5194/nhess-23-2403-2023, 2023
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We studied annual maximum sea levels in the Finnish coastal region. Our aim was to better quantify the uncertainty in them compared to previous studies. Using four statistical models, we found out that hierarchical models, which shared information on sea-level extremes across Finnish tide gauges, had lower uncertainty in their results in comparison with tide-gauge-specific fits. These models also suggested that the shape of the distribution for extreme sea levels is similar on the Finnish coast.
Havu Pellikka, Milla M. Johansson, Maaria Nordman, and Kimmo Ruosteenoja
Nat. Hazards Earth Syst. Sci., 23, 1613–1630, https://doi.org/10.5194/nhess-23-1613-2023, https://doi.org/10.5194/nhess-23-1613-2023, 2023
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We explore the rate of past and future sea level rise at the Finnish coast, northeastern Baltic Sea, in 1901–2100. For this analysis, we use tide gauge observations, modelling results, and a probabilistic method to combine information from several sea level rise projections. We provide projections of local mean sea level by 2100 as probability distributions. The results can be used in adaptation planning in various sectors with different risk tolerance, e.g. land use planning or nuclear safety.
Lea Fink, Matthias Karl, Volker Matthias, Sonia Oppo, Richard Kranenburg, Jeroen Kuenen, Jana Moldanova, Sara Jutterström, Jukka-Pekka Jalkanen, and Elisa Majamäki
Atmos. Chem. Phys., 23, 1825–1862, https://doi.org/10.5194/acp-23-1825-2023, https://doi.org/10.5194/acp-23-1825-2023, 2023
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Potential ship impact on air pollution in the Mediterranean Sea was simulated with five chemistry transport models. An evaluation of the results for NO2 and O3 air concentrations and dry deposition is presented. Emission data, modeled year and domain were the same. Model run outputs were compared to measurements from background stations. We focused on comparing model outputs regarding the concentration of regulatory pollutants and the relative ship impact on total air pollution concentrations.
Matti Räsänen, Mika Aurela, Ville Vakkari, Johan P. Beukes, Juha-Pekka Tuovinen, Pieter G. Van Zyl, Miroslav Josipovic, Stefan J. Siebert, Tuomas Laurila, Markku Kulmala, Lauri Laakso, Janne Rinne, Ram Oren, and Gabriel Katul
Hydrol. Earth Syst. Sci., 26, 5773–5791, https://doi.org/10.5194/hess-26-5773-2022, https://doi.org/10.5194/hess-26-5773-2022, 2022
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The productivity of semiarid grazed grasslands is linked to the variation in rainfall and transpiration. By combining carbon dioxide and water flux measurements, we show that the annual transpiration is nearly constant during wet years while grasses react quickly to dry spells and drought, which reduce transpiration. The planning of annual grazing strategies could consider the early-season rainfall frequency that was linked to the portion of annual transpiration.
Jenna Ritvanen, Ewan O'Connor, Dmitri Moisseev, Raisa Lehtinen, Jani Tyynelä, and Ludovic Thobois
Atmos. Meas. Tech., 15, 6507–6519, https://doi.org/10.5194/amt-15-6507-2022, https://doi.org/10.5194/amt-15-6507-2022, 2022
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Doppler lidars and weather radars provide accurate wind measurements, with Doppler lidar usually performing better in dry weather conditions and weather radar performing better when there is precipitation. Operating both instruments together should therefore improve the overall performance. We investigate how well a co-located Doppler lidar and X-band radar perform with respect to various weather conditions, including changes in horizontal visibility, cloud altitude, and precipitation.
Mikko Lensu and Markku Similä
The Cryosphere, 16, 4363–4377, https://doi.org/10.5194/tc-16-4363-2022, https://doi.org/10.5194/tc-16-4363-2022, 2022
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Ice ridges form a compressing ice cover. From above they appear as walls of up to few metres in height and extend even kilometres across the ice. Below they may reach tens of metres under the sea surface. Ridges need to be observed for the purposes of ice forecasting and ice information production. This relies mostly on ridging signatures discernible in radar satellite (SAR) images. New methods to quantify ridging from SAR have been developed and are shown to agree with field observations.
Marc Guevara, Hervé Petetin, Oriol Jorba, Hugo Denier van der Gon, Jeroen Kuenen, Ingrid Super, Jukka-Pekka Jalkanen, Elisa Majamäki, Lasse Johansson, Vincent-Henri Peuch, and Carlos Pérez García-Pando
Earth Syst. Sci. Data, 14, 2521–2552, https://doi.org/10.5194/essd-14-2521-2022, https://doi.org/10.5194/essd-14-2521-2022, 2022
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To control the spread of the COVID-19 disease, European governments implemented mobility restriction measures that resulted in an unprecedented drop in anthropogenic emissions. This work presents a dataset of emission adjustment factors that allows quantifying changes in 2020 European primary emissions per country and pollutant sector at the daily scale. The resulting dataset can be used as input in modelling studies aiming at quantifying the impact of COVID-19 on air quality levels.
Ranjeet S. Sokhi, Nicolas Moussiopoulos, Alexander Baklanov, John Bartzis, Isabelle Coll, Sandro Finardi, Rainer Friedrich, Camilla Geels, Tiia Grönholm, Tomas Halenka, Matthias Ketzel, Androniki Maragkidou, Volker Matthias, Jana Moldanova, Leonidas Ntziachristos, Klaus Schäfer, Peter Suppan, George Tsegas, Greg Carmichael, Vicente Franco, Steve Hanna, Jukka-Pekka Jalkanen, Guus J. M. Velders, and Jaakko Kukkonen
Atmos. Chem. Phys., 22, 4615–4703, https://doi.org/10.5194/acp-22-4615-2022, https://doi.org/10.5194/acp-22-4615-2022, 2022
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This review of air quality research focuses on developments over the past decade. The article considers current and future challenges that are important from air quality research and policy perspectives and highlights emerging prominent gaps of knowledge. The review also examines how air pollution management needs to adapt to new challenges and makes recommendations to guide the direction for future air quality research within the wider community and to provide support for policy.
Milla M. Johansson, Jan-Victor Björkqvist, Jani Särkkä, Ulpu Leijala, and Kimmo K. Kahma
Nat. Hazards Earth Syst. Sci., 22, 813–829, https://doi.org/10.5194/nhess-22-813-2022, https://doi.org/10.5194/nhess-22-813-2022, 2022
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We analysed the correlation of sea level and wind waves at a coastal location in the Gulf of Finland using tide gauge data, wave measurements, and wave simulations. The correlation was positive for southwesterly winds and negative for northeasterly winds. Probabilities of high total water levels (sea level + wave crest) are underestimated if sea level and waves are considered independent. Suitably chosen copula functions can account for the dependence.
Jeroen Kuenen, Stijn Dellaert, Antoon Visschedijk, Jukka-Pekka Jalkanen, Ingrid Super, and Hugo Denier van der Gon
Earth Syst. Sci. Data, 14, 491–515, https://doi.org/10.5194/essd-14-491-2022, https://doi.org/10.5194/essd-14-491-2022, 2022
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This paper presents an 18-year time series for anthropogenic emissions for the main air pollutants in Europe, distinguishing 15 main source categories. It provides a complete overview of emissions to air and is designed to support air quality modelling. The data build where possible on official country total emissions used in the policy processes, but where necessary alternative data were used. The emission data are spatially distributed at high resolution (~ 6 km x 6 km) in a consistent way.
Marcus Reckermann, Anders Omstedt, Tarmo Soomere, Juris Aigars, Naveed Akhtar, Magdalena Bełdowska, Jacek Bełdowski, Tom Cronin, Michał Czub, Margit Eero, Kari Petri Hyytiäinen, Jukka-Pekka Jalkanen, Anders Kiessling, Erik Kjellström, Karol Kuliński, Xiaoli Guo Larsén, Michelle McCrackin, H. E. Markus Meier, Sonja Oberbeckmann, Kevin Parnell, Cristian Pons-Seres de Brauwer, Anneli Poska, Jarkko Saarinen, Beata Szymczycha, Emma Undeman, Anders Wörman, and Eduardo Zorita
Earth Syst. Dynam., 13, 1–80, https://doi.org/10.5194/esd-13-1-2022, https://doi.org/10.5194/esd-13-1-2022, 2022
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As part of the Baltic Earth Assessment Reports (BEAR), we present an inventory and discussion of different human-induced factors and processes affecting the environment of the Baltic Sea region and their interrelations. Some are naturally occurring and modified by human activities, others are completely human-induced, and they are all interrelated to different degrees. The findings from this study can largely be transferred to other comparable marginal and coastal seas in the world.
Jari Walden, Liisa Pirjola, Tuomas Laurila, Juha Hatakka, Heidi Pettersson, Tuomas Walden, Jukka-Pekka Jalkanen, Harri Nordlund, Toivo Truuts, Miika Meretoja, and Kimmo K. Kahma
Atmos. Chem. Phys., 21, 18175–18194, https://doi.org/10.5194/acp-21-18175-2021, https://doi.org/10.5194/acp-21-18175-2021, 2021
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Ship emissions play an important role in the deposition of gaseous compounds and nanoparticles (Ntot), affecting climate, human health (especially in coastal areas), and eutrophication. Micrometeorological methods showed that ship emissions were mainly responsible for the deposition of Ntot, whereas they only accounted for a minor proportion of CO2 deposition. An uncertainty analysis applied to the fluxes and fuel sulfur content results demonstrated the reliability of the results.
Martti Honkanen, Jens Daniel Müller, Jukka Seppälä, Gregor Rehder, Sami Kielosto, Pasi Ylöstalo, Timo Mäkelä, Juha Hatakka, and Lauri Laakso
Ocean Sci., 17, 1657–1675, https://doi.org/10.5194/os-17-1657-2021, https://doi.org/10.5194/os-17-1657-2021, 2021
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The exchange of carbon dioxide (CO2) between the sea and the atmosphere is regulated by the gradient of CO2 partial pressure (pCO2) between the sea and the air. The daily variation of the seawater pCO2 recorded at the fixed station Utö in the Baltic Sea was found to be mainly biologically driven. Calculation of the annual net exchange of CO2 between the sea and atmosphere based on daily measurements of pCO2 carried out using the same sampling time every day could introduce a bias of up to 12 %.
Camilla Geels, Morten Winther, Camilla Andersson, Jukka-Pekka Jalkanen, Jørgen Brandt, Lise M. Frohn, Ulas Im, Wing Leung, and Jesper H. Christensen
Atmos. Chem. Phys., 21, 12495–12519, https://doi.org/10.5194/acp-21-12495-2021, https://doi.org/10.5194/acp-21-12495-2021, 2021
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In this study, we set up new shipping emissions scenarios and use two chemistry transport models and a health assessment model to assess the development of air quality and related health impacts in the Nordic region. Shipping alone is associated with about 850 premature deaths during present-day conditions, decreasing to approximately 550–600 cases in the 2050 scenarios.
Jukka-Pekka Jalkanen, Lasse Johansson, Magda Wilewska-Bien, Lena Granhag, Erik Ytreberg, K. Martin Eriksson, Daniel Yngsell, Ida-Maja Hassellöv, Kerstin Magnusson, Urmas Raudsepp, Ilja Maljutenko, Hulda Winnes, and Jana Moldanova
Ocean Sci., 17, 699–728, https://doi.org/10.5194/os-17-699-2021, https://doi.org/10.5194/os-17-699-2021, 2021
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This modelling study describes a methodology for describing pollutant discharges from ships to the sea. The pilot area used is the Baltic Sea area and discharges of bilge, ballast, sewage, wash water as well as stern tube oil are reported for the year 2012. This work also reports the release of SOx scrubber effluents. This technique may be used by ships to comply with tight sulfur limits inside Emission Control Areas, but it also introduces a new pollutant stream from ships to the sea.
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Short summary
We present an experimental Automatic Identification System (AIS) receiver set-up to study anomalous signal propagation over coastal and marine waters in the northern Baltic Sea. Anomalous atmospheric conditions can allow for the AIS messages to be received from farther distances than under normal conditions. The results show that under anomalous conditions, the messages can be received up to 600 km away and have both diurnal and seasonal cycles.
We present an experimental Automatic Identification System (AIS) receiver set-up to study...
