Browsing by Subject "1171 Geosciences"

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  • Mäkelä, Samppa (2018)
    The objective of this study is to develop a method of appraising rock aggregate resources, using open data and open source tools. The availability of aggregates in Finland is mostly determined by competing land use and restrictions on extraction. Therefore, it is important to determine the extent of available resources, especially near areas of high demand. The study area consists of the 14 municipalities in the Helsinki metropolitan area, a total of 3841 km(2). The data used are open access, provided by the Geological Survey of Finland and the National Land Survey. These are combined in a GIS to identify locations where extraction of aggregates is possible. Geology, limitations and the highest and lowest point of possible extraction are determined. These are used to estimate the available resources and locate the economically feasible sites. Data used include a digital elevation model and layers on geology and land use. The results show that competing land use has sterilized most aggregate locations in the area. Remaining locations are concentrated on the edges. However, some potential sites remain. Field evaluations and comparison to previous studies show that the method has potential in evaluating remaining resources and directing further study for prospective production areas. The model is fast in coarsely determining aggregate volume. It is highly suitable for focusing expert fieldwork. Land use in the area continues to sterilize new locations. To avoid economic and ecological damage, a plan should be implemented for securing this resource. This may include the reserving of locations, reducing use, checking legislation on production and recycling used aggregates.
  • Neefjes, Ivo; Laapas, Mikko; Liu, Yang; Medus, Erika; Miettunen, Elina; Ahonen, Lauri; Quelever, Lauriane; Aalto, Juho; Bäck, Jaana; Kerminen, Veli-Matti; Lampilahti, Janne; Luoma, Krista; Mäki, Mari; Mammarella, Ivan; Petäjä, Tuukka; Räty, Meri; Sarnela, Nina; Ylivinkka, Ilona; Hakala, Simo; Kulmala, Markku; Nieminen, Tuomo; Lintunen, Anna (2022)
    Boreal forests are an important source of trace gases and atmospheric aerosols, as well as a crucial carbon sink. As such, they form a strongly interconnected coupled system with the atmosphere. The SMEAR II station is located in a boreal Scots pine forest in Hyytiala, Finland, and has over 25 years of continuous measurements of atmospheric and ecosystem variables. In this study, we analyse the seasonal variations of trace gases, atmospheric aerosols, greenhouse gases, and meteorological variables, measured at the SMEAR II sta-tion during the past two and a half decades. Several ecosystem and atmospheric variables show seasonal correlations with each other, which suggests seasonal interactions within the climate system that links together ecosystem processes, greenhouse gases, trace gases and atmospheric aerosols. For instance, increased global radiation in summer increases air temperature and consequently affects the plant phenology, which promotes the ecosystem carbon exchange and biogenic volatile organic compound (biogenic VOC) release. This further affects the ambient concentrations of highly oxygenated organic molecules (HOMs) as well as the formation and growth of atmospheric organic aerosols. Organic aerosols subsequently influence aerosol optical properties and, through increased scattering, have the potential to cool the climate. We also discuss the impacts of the warm and dry summers of 2010 and 2018 on the studied variables. For these years, we find a higher-than-average ecosystem primary production especially in June, leading to an increased VOC flux from the forest. The increased VOC flux in turn leads to higher HOM and secondary aerosol concentration in the atmosphere. The latter increases light scattering by atmospheric aero-sol particles and thus leads to climate cooling. The results obtained in this study improve our understanding of how boreal forests respond to climate change.
  • Väkevä, Lauri Sakari Oleksi; Koivisto, Emilia Anna-Liisa; Hillers, Gregor; Chamarczuk, Michal; Malinowski, Michal (Institute of Seismology, University of Helsinki, 2018)
  • Kauti, Tuomas; Skyttä, Pietari; Koivisto, Emilia; Savolainen, Mikko (Luleå University of Technology, 2019)
  • Qi, Lu; Vogel, Alexander L.; Esmaeilirad, Sepideh; Cao, Liming; Zheng, Jing; Jaffrezo, Jean-Luc; Fermo, Paola; Kasper-Giebl, Anne; Dällenbach, Kaspar; Chen, Mindong; Ge, Xinlei; Baltensperger, Urs; Prevot, Andre S. H.; Slowik, Jay G. (2020)
    The aerosol mass spectrometer (AMS), combined with statistical methods such as positive matrix factorization (PMF), has greatly advanced the quantification of primary organic aerosol (POA) sources and total secondary organic aerosol (SOA) mass. However, the use of thermal vaporization and electron ionization yields extensive thermal decomposition and ionization-induced fragmentation, which limit chemical information needed for SOA source apportionment. The recently developed extractive electrospray ionization time-of-flight mass spectrometer (EESI-TOF) provides mass spectra of the organic aerosol fraction with a linear response to mass and no thermal decomposition or ionization-induced fragmentation. However, the costs and operational requirements of online instruments make their use impractical for long-term or spatially dense monitoring applications. This challenge was overcome for AMS measurements by measuring re-nebulized water extracts from ambient filter samples. Here, we apply the same strategy for EESI-TOF measurements of 1 year of 24 h filter samples collected approximately every fourth day throughout 2013 at an urban site. The nebulized water extracts were measured simultaneously with an AMS. The application of positive matrix factorization (PMF) to EESI-TOF spectra resolved seven factors, which describe water-soluble OA: less and more aged biomass burning aerosol (LABB(EESI) and MABB(EESI), respectively), cigarette-smoke-related organic aerosol, primary biological organic aerosol, biogenic secondary organic aerosol, and a summer mixed oxygenated organic aerosol factor. Seasonal trends and relative contributions of the EESI-TOF OA sources were compared with AMS source apportionment factors, measured water-soluble ions, cellulose, and meteorological data. Cluster analysis was utilized to identify key factor-specific ions based on PMF. Both LABB and MABB contribute strongly during winter. LABB is distinguished by very high signals from C6H10O5 (levoglucosan and isomers) and C8H12O6, whereas MABB is characterized by a large number of CxHyOz and CxHyOzN species of two distinct populations: one with low H : C and high O : C and the other with high H : C and low O : C. Two oxygenated summertime SOA sources were attributed to terpene-derived biogenic SOA, a major summertime aerosol source in central Europe. Furthermore, a primary biological organic aerosol factor was identified, which was dominated by plant-derived fatty acids and correlated with free cellulose. The cigarette-smoke-related factor contained a high contribution of nicotine and high abundance of organic nitrate ions with low m/z.
  • Bergroth, Claudia; Järv, Olle; Tenkanen, Henrikki; Manninen, Matti; Toivonen, Tuuli (2022)
    In this article, we present temporally dynamic population distribution data from the Helsinki Metropolitan Area, Finland, at the level of 250 m by 250 m statistical grid cells. An hourly population distribution dataset is provided for regular workdays (Mon – Thu), Saturdays and Sundays. The data are based on aggregated mobile phone data collected by the biggest mobile network operator in Finland. Mobile phone data are assigned to statistical grid cells using an advanced dasymetric interpolation method based on ancillary data about land cover, buildings and a time use survey. The dataset is validated by comparing population register data from Statistics Finland for night hours and a daytime workplace registry. The resulting 24-hour population data can be used to reveal the temporal dynamics of the city, and examine population variations relevant to spatial accessibility analyses, crisis management, planning and beyond.
  • Arppe, Laura; Kurki, Eija; Wooller, Matthew J.; Luoto, Tomi P.; Zajaczkowski, Marek; Ojala, Antti E. K. (2017)
    The oxygen isotope composition of chironomid head capsules in a sediment core spanning the past 5500 years from Lake Svartvatnet in southern Spitsbergen was used to reconstruct the oxygen isotope composition of lake water (O-18(lw)) and local precipitation. The O-18(lw) values display shifts from the baseline variability consistent with the timing of recognized historical climatic episodes, such as the Roman Warm Period, the Dark Ages Cold Period and the Little Ice Age'. The highest values of the record, ca. 3 parts per thousand above modern O-18(lw) values, occur at ca. 1900-1800 cal. yr BP. Three negative excursions increasing in intensity toward the present, at 3400-3200, 1250-1100, and 350-50 cal. yr BP, are tentatively linked to roughly synchronous episodes of increased glacier activity and general cold spells around the northern North Atlantic. Their manifestation in the Svartvatnet O-18(lw) record not only testify to the sensitivity and potential of high Arctic lacustrine O-18(chir) records in tracking terrestrial climate evolution but also highlight nonlinear dynamics within the northern North Atlantic hydroclimatic system. The Little Ice Age' period at 350-50 cal. yr BP displays a remarkable 8-9 parts per thousand drop in O-18(lw) values, construed to predominantly represent significantly decreased winter temperatures during a period of increased seasonal differences and extended sea ice cover inducing changes in moisture source regions.
  • Gibbons, S. J.; Kvaerna, Tormod; Tiira, T.; Kozlovskaya, Elena (2020)
    'Precision seismology' encompasses a set of methods which use differential measurements of time-delays to estimate the relative locations of earthquakes and explosions. Delay-times estimated from signal correlations often allow far more accurate estimates of one event location relative to another than is possible using classical hypocentre determination techniques. Many different algorithms and software implementations have been developed and different assumptions and procedures can often result in significant variability between different relative event location estimates. We present a Ground Truth (GT) dataset of 55 military surface explosions in northern Finland in 2007 that all took place within 300 m of each other. The explosions were recorded with a high signal-to-noise ratio to distances of about 2 degrees, and the exceptional waveform similarity between the signals from the different explosions allows for accurate correlation-based time-delay measurements. With exact coordinates for the explosions, we are able to assess the fidelity of relative location estimates made using any location algorithm or implementation. Applying double-difference calculations using two different 1-D velocity models for the region results in hypocentre-to-hypocentre distances which are too short and it is clear that the wavefield leaving the source region is more complicated than predicted by the models. Using the GT event coordinates, we are able to measure the slowness vectors associated with each outgoing ray from the source region. We demonstrate that, had such corrections been available, a significant improvement in the relative location estimates would have resulted. In practice we would of course need to solve for event hypocentres and slowness corrections simultaneously, and significant work will be needed to upgrade relative location algorithms to accommodate uncertainty in the form of the outgoing wavefield. We present this data set, together with GT coordinates, raw waveforms for all events on six regional stations, and tables of time-delay measurements, as a reference benchmark by which relative location algorithms and software can be evaluated.
  • Azevedo, Anna Karoline; Vieira, Felipe A. S.; Guedes-Santos, Jhonatan; Gaia, Joao Arthur; Pinheiro, Barbara R.; Bragagnolo, Chiara; Correia, Ricardo A.; Ladle, Richard J.; Malhado, Ana C. M. (2022)
    In August 2019, the Northeast coast of Brazil was impacted by an extensive oil spill, with immediate effects on marine and coastal ecosystems and significant impacts on tourism and food security. The human dimension of those impacts also includes the loss of cultural ecosystem services (CES); the non-material benefits stemming from strongly rooted cultural practices and relationships with nature. CES are of great importance for local residents and visitors that flock to Brazilian iconic beaches, however, they are difficult to measure using traditional assessment methods due to their subjective and non-tangible nature. Here, we use a big data approach to assess and map the loss of CES in the Northeast coast of Brazil caused by the recent oil spill. We analysed 2,880 digital images (published on the image sharing platform Flickr) taken before and during the disaster in affected locations, using a combination of automated techniques. Results showed a sharp decline in the number of users posting photos of locations affected by oil spill, and a decline in photos representing landscape and cultural appreciation. Our big data approach provides a fast and automated way to assess CES at large spatial scales that can be used to monitor the social impacts of environmental disasters.
  • Brugnara, Y.; Auchmann, R.; Broennimann, S.; Allan, R. J.; Auer, I.; Barriendos, M.; Bergstrom, H.; Bhend, J.; Brazdil, R.; Compo, G. P.; Cornes, R. C.; Dominguez-Castro, F.; van Engelen, A. F. V.; Filipiak, J.; Holopainen, J.; Jourdain, S.; Kunz, M.; Luterbacher, J.; Maugeri, M.; Mercalli, L.; Moberg, A.; Mock, C. J.; Pichard, G.; Reznckova, L.; van der Schrier, G.; Slonosky, V.; Ustrnul, Z.; Valente, M. A.; Wypych, A.; Yin, X. (2015)
    The eruption of Mount Tambora (Indonesia) in April 1815 is the largest documented volcanic eruption in history. It is associated with a large global cooling during the following year, felt particularly in parts of Europe and North America, where the year 1816 became known as the "year without a summer". This paper describes an effort made to collect surface meteorological observations from the early instrumental period, with a focus on the years of and immediately following the eruption (1815-1817). Although the collection aimed in particular at pressure observations, correspondent temperature observations were also recovered. Some of the series had already been described in the literature, but a large part of the data, recently digitised from original weather diaries and contemporary magazines and newspapers, is presented here for the first time. The collection puts together more than 50 sub-daily series from land observatories in Europe and North America and from ships in the tropics. The pressure observations have been corrected for temperature and gravity and reduced to mean sea level. Moreover, an additional statistical correction was applied to take into account common error sources in mercury barometers. To assess the reliability of the corrected data set, the variance in the pressure observations is compared with modern climatologies, and single observations are used for synoptic analyses of three case studies in Europe. All raw observations will be made available to the scientific community in the International Surface Pressure Databank.
  • Hernández-Uribe, David; Spera, Frank J.; Bohrson, Wendy A.; Heinonen, Jussi S. (2022)
    Phase equilibria modeling is a powerful petrological tool to address both forward and inverse geological problems over a broad range of crustal and upper mantle conditions of pressure (P), temperature (T), composition (X), and redox (f(o2)). The development of thermodynamic databases, relatively realistic activity-composition (a-X) relations for solids, melts and fluids, pressure-volume-temperature (PVT) equations of state (EOS), and efficient numerical algorithms represent an inflection point in our ability to understand the nexus between tectonics and petrogenesis. While developed-and typically applied in isolation-by either metamorphic or igneous petrologists, some of the published thermodynamic models have overlapping P-T-X calibration ranges, which enables comparisons of model outcomes for similar conditions within the range of applicability. In this paper, we systematically compare the results of two such models that are routinely used for calculating phase equilibria in melt-bearing systems: rhyolite-MELTS (Gualda et al. 2012; Ghiorso and Gualda 2015) and the metabasite set of Green et al. (2016) using the thermodynamic database ds62 (Holland and Powell 2011) (hereafter denoted as "HPx-mb16"). We selected a N-MORB composition and modeled closed system equilibrium phase relations as a function of temperature at 0.25 and 1 GPa for N-MORB with 0.5 and 4 wt% H2O. Our results show that phase relations exhibit some key differences that, in some instances, impact geological inferences. For example, clinopyroxene and plagioclase stabilities are expanded to higher temperatures in HPx-mb16 compared to predictions from rhyolite-MELTS. Orthopyroxene and olivine are stable in greater proportions and at wider temperature ranges in rhyolite-MELTS compared to HPx-mb16. Importantly, HPx-mb16 predicts amphibole in all runs presented here, whereas amphibole is only predicted at high-P-high-H2O (1 GPa and 4 wt% H2O) in rhyolite-MELTS, and in lesser amounts. Garnet stability is systematically expanded at higher temperatures, and the proportion is greater in rhyolite-MELTS. In addition to phase assemblage differences, phase compositions may differ. For example, plagioclase anorthite content is systematically higher in HPx-mb16 (for the same set of conditions), whereas garnet Mg# is higher in rhyolite-MELTS. Calculated amphibole compositions are substantially different between the two models as well. Liquid compositions also show important differences. High-T liquids are generally similar in SiO2 contents but diverge at lower temperatures; in these cases, HIPx-mb16 liquids are SiO2-depleted compared to those produced by rhyolite-MELTS. Liquids are also systematically and substantially more mafic in HPx-mb16, and alumina and the alkali concentrations are relatively different and show different trends as a function of temperature at constant pressure. Overall, liquid compositions show the greatest differences near the solidus. Differences in modal abundances of phases and liquid compositions influence liquid trace-element signatures, and these differences can affect geological interpretations. Finally, a comparison between melting experiments of basaltic bulk composition and both thermodynamic models shows that rhyolite-MELTS better reproduces the higher temperature experiments, whereas HPx-mb16 better reproduces the lower temperature experiments. We discuss these and other similarities and differences to highlight the strengths and limitations of each model and to recognize that modeling results have important implications for interpretations of geologic processes. We recognize that our results are informed by a small subset of calculations over a limited range of conditions-but encourage further comparisons over a wider range of conditions and compositions.
  • Oswald, R.; Ermel, M.; Hens, K.; Novelli, A.; Ouwersloot, H. G.; Paasonen, Pauli; Petäjä, Tuukka; Sipilä, Mikko; Keronen, Petri; Bäck, Jaana; Konigstedt, R.; Beygi, Z. Hosaynali; Fischer, H.; Bohn, B.; Kubistin, D.; Harder, H.; Martinez, M.; Williams, J.; Hoffmann, T.; Trebs, I.; Soergel, M. (2015)
  • Peltoniemi, J. I.; Gritsevich, M.; Markkanen, J.; Hakala, T.; Suomalainen, J.; Zubko, N.; Wilkman, O.; Muinonen, Karri (2020)
  • Silva, S. J.; Heald, C. L.; Ravela, S.; Mammarella, I.; Munger, J. William (2019)
    The loss of ozone to terrestrial and aquatic systems, known as dry deposition, is a highly uncertain process governed by turbulent transport, interfacial chemistry, and plant physiology. We demonstrate the value of using Deep Neural Networks (DNN) in predicting ozone dry deposition velocities. We find that a feedforward DNN trained on observations from a coniferous forest site (Hyytiala, Finland) can predict hourly ozone dry deposition velocities at a mixed forest site (Harvard Forest, Massachusetts) more accurately than modern theoretical models, with a reduction in the normalized mean bias (0.05 versus similar to 0.1). The same DNN model, when driven by assimilated meteorology at 2 degrees x 2.5 degrees spatial resolution, outperforms the Wesely scheme as implemented in the GEOS-Chem model. With more available training data from other climate and ecological zones, this methodology could yield a generalizable DNN suitable for global models. Plain Language Summary Ozone in the lower atmosphere is a toxic pollutant and greenhouse gas. In this work, we use a machine learning technique known as deep learning, to simulate the loss of ozone to Earth's surface. We show that our deep learning simulation of this loss process outperforms existing traditional models and demonstrate the opportunity for using machine learning to improve our understanding of the chemical composition of the atmosphere.
  • Golub, Malgorzata; Thiery, Wim; Marce, Rafael; Pierson, Don; Vanderkelen, Inne; Mercado-Bettin, Daniel; Woolway, R. Iestyn; Grant, Luke; Jennings, Eleanor; Kraemer, Benjamin M.; Schewe, Jacob; Zhao, Fang; Frieler, Katja; Mengel, Matthias; Bogomolov, Vasiliy Y.; Bouffard, Damien; Cote, Marianne; Couture, Raoul-Marie; Debolskiy, Andrey; Droppers, Bram; Gal, Gideon; Guo, Mingyang; Janssen, Annette B. G.; Kirillin, Georgiy; Ladwig, Robert; Magee, Madeline; Moore, Tadhg; Perroud, Marjorie; Piccolroaz, Sebastiano; Vinnaa, Love Raaman; Schmid, Martin; Shatwell, Tom; Stepanenko, Victor M.; Tan, Zeli; Woodward, Bronwyn; Yao, Huaxia; Adrian, Rita; Allan, Mathew; Anneville, Orlane; Arvola, Lauri; Atkins, Karen; Boegman, Leon; Carey, Cayelan; Christianson, Kyle; de Eyto, Elvira; DeGasperi, Curtis; Grechushnikova, Maria; Hejzlar, Josef; Joehnk, Klaus; Jones, Ian D.; Laas, Alo; Mackay, Eleanor B.; Mammarella, Ivan; Markensten, Hampus; McBride, Chris; Ozkundakci, Deniz; Potes, Miguel; Rinke, Karsten; Robertson, Dale; Rusak, James A.; Salgado, Rui; van der Linden, Leon; Verburg, Piet; Wain, Danielle; Ward, Nicole K.; Wollrab, Sabine; Zdorovennova, Galina (2022)
    Empirical evidence demonstrates that lakes and reservoirs are warming across the globe. Consequently, there is an increased need to project future changes in lake thermal structure and resulting changes in lake biogeochemistry in order to plan for the likely impacts. Previous studies of the impacts of climate change on lakes have often relied on a single model forced with limited scenario-driven projections of future climate for a relatively small number of lakes. As a result, our understanding of the effects of climate change on lakes is fragmentary, based on scattered studies using different data sources and modelling protocols, and mainly focused on individual lakes or lake regions. This has precluded identification of the main impacts of climate change on lakes at global and regional scales and has likely contributed to the lack of lake water quality considerations in policy-relevant documents, such as the Assessment Reports of the Intergovernmental Panel on Climate Change (IPCC). Here, we describe a simulation protocol developed by the Lake Sector of the Inter-Sectoral Impact Model Intercomparison Project (ISIMIP) for simulating climate change impacts on lakes using an ensemble of lake models and climate change scenarios for ISIMIP phases 2 and 3. The protocol prescribes lake simulations driven by climate forcing from gridded observations and different Earth system models under various representative greenhouse gas concentration pathways (RCPs), all consistently bias-corrected on a 0.5 degrees x 0.5 degrees global grid. In ISIMIP phase 2, 11 lake models were forced with these data to project the thermal structure of 62 well-studied lakes where data were available for calibration under historical conditions, and using uncalibrated models for 17 500 lakes defined for all global grid cells containing lakes. In ISIMIP phase 3, this approach was expanded to consider more lakes, more models, and more processes. The ISIMIP Lake Sector is the largest international effort to project future water temperature, thermal structure, and ice phenology of lakes at local and global scales and paves the way for future simulations of the impacts of climate change on water quality and biogeochemistry in lakes.
  • Laj, Paolo; Bigi, Alessandro; Rose, Clemence; Andrews, Elisabeth; Myhre, Cathrine Lund; Coen, Martine Collaud; Lin, Yong; Wiedensohler, Alfred; Schulz, Michael; Ogren, John A.; Fiebig, Markus; Gliss, Jonas; Mortier, Augustin; Pandolfi, Marco; Petäjä, Tuukka; Kim, Sang-Woo; Aas, Wenche; Putaud, Jean-Philippe; Mayol-Bracero, Olga; Keywood, Melita; Labrador, Lorenzo; Aalto, Pasi; Ahlberg, Erik; Alados Arboledas, Lucas; Alastuey, Andres; Andrade, Marcos; Artinano, Begona; Ausmeel, Stina; Arsov, Todor; Asmi, Eija; Backman, John; Baltensperger, Urs; Bastian, Susanne; Bath, Olaf; Beukes, Johan Paul; Brem, Benjamin T.; Bukowiecki, Nicolas; Conil, Sebastien; Couret, Cedric; Day, Derek; Dayantolis, Wan; Degorska, Anna; Eleftheriadis, Konstantinos; Fetfatzis, Prodromos; Favez, Olivier; Flentje, Harald; Gini, Maria I.; Gregoric, Asta; Gysel-Beer, Martin; Hallar, A. Gannet; Hand, Jenny; Hoffer, Andras; Hueglin, Christoph; Hooda, Rakesh K.; Hyvärinen, Antti; Kalapov, Ivo; Kalivitis, Nikos; Kasper-Giebl, Anne; Kim, Jeong Eun; Kouvarakis, Giorgos; Kranjc, Irena; Krejci, Radovan; Kulmala, Markku; Labuschagne, Casper; Lee, Hae-Jung; Lihavainen, Heikki; Lin, Neng-Huei; Loeschau, Gunter; Luoma, Krista; Marinoni, Angela; Dos Santos, Sebastiao Martins; Meinhardt, Frank; Merkel, Maik; Metzger, Jean-Marc; Mihalopoulos, Nikolaos; Nhat Anh Nguyen; Ondracek, Jakub; Perez, Noemi; Perrone, Maria Rita; Petit, Jean-Eudes; Picard, David; Pichon, Jean-Marc; Pont, Veronique; Prats, Natalia; Prenni, Anthony; Reisen, Fabienne; Romano, Salvatore; Sellegri, Karine; Sharma, Sangeeta; Schauer, Gerhard; Sheridan, Patrick; Sherman, James Patrick; Schuetze, Maik; Schwerin, Andreas; Sohmer, Ralf; Sorribas, Mar; Steinbacher, Martin; Sun, Junying; Titos, Gloria; Toczko, Barbara; Tuch, Thomas; Tulet, Pierre; Tunved, Peter; Vakkari, Ville; Velarde, Fernando; Velasquez, Patricio; Villani, Paolo; Vratolis, Sterios; Wang, Sheng-Hsiang; Weinhold, Kay; Weller, Rolf; Yela, Margarita; Yus-Diez, Jesus; Zdimal, Vladimir; Zieger, Paul; Zikova, Nadezda (2020)
    Aerosol particles are essential constituents of the Earth's atmosphere, impacting the earth radiation balance directly by scattering and absorbing solar radiation, and indirectly by acting as cloud condensation nuclei. In contrast to most greenhouse gases, aerosol particles have short atmospheric residence times, resulting in a highly heterogeneous distribution in space and time. There is a clear need to document this variability at regional scale through observations involving, in particular, the in situ near-surface segment of the atmospheric observation system. This paper will provide the widest effort so far to document variability of climate-relevant in situ aerosol properties (namely wavelength dependent particle light scattering and absorption coefficients, particle number concentration and particle number size distribution) from all sites connected to the Global Atmosphere Watch network. High-quality data from almost 90 stations worldwide have been collected and controlled for quality and are reported for a reference year in 2017, providing a very extended and robust view of the variability of these variables worldwide. The range of variability observed worldwide for light scattering and absorption coefficients, single-scattering albedo, and particle number concentration are presented together with preliminary information on their long-term trends and comparison with model simulation for the different stations. The scope of the present paper is also to provide the necessary suite of information, including data provision procedures, quality control and analysis, data policy, and usage of the ground-based aerosol measurement network. It delivers to users of the World Data Centre on Aerosol, the required confidence in data products in the form of a fully characterized value chain, including uncertainty estimation and requirements for contributing to the global climate monitoring system.
  • Kaufman, Darrell S.; McKay, Nicholas P.; Routson, Cody; Erb, Michael; Davis, Basil A. S.; Heiri, Oliver; Jaccard, Samuel; Tierney, Jessica; Dätwyler, Christoph; Axford, Yarrow; Brussel, Thomas; Cartapanis, Olivier; Chase, Brian M.; Dawson, Andria; de Vernal, Anne; Engels, Stefan; Jonkers, Lukas; Marsicek, Jeremiah; Moffa-Sánchez, Paola; Morrill, Carrie; Orsi, Anais; Rehfeld, Kira; Saunders, Krystyna; Sommer, Philipp S.; Thomas, Elizabeth K.; Tonello, Marcela S.; Toth, Monika; Vachula, Richard; Andreev, Andrei A; Bertrand, Sebastien; Biskaborn, Boris; Bringue, Manuel; Brooks, Stephen J.; Caniupán, Magaly; Chevalier, Manuel; Cwynar, Les C.; Emile-Geay, Julien; Fegyveresi, John; Feurdean, Angelica; Finsinger, Walter; Fortin, Marie-Claude; Foster, Louise; Fox, Mathew; Gajewski, Konrad; Grosjean, Martin; Hausmann, Sonja; Heinrichs, Markus; Holmes, Naomi; Ilyashuk, Boris; Ilyashuk, Elena; Juggins, Steve; Khider, Deborah; Koinig, Karin A.; Langdon, Peter; Larocque-Tobler, Isabelle; Li, Jianyong; Lotter, Andre F.; Luoto, Tomi P.; Mackay, Anson W.; Magyari, Eniko; Malevich, Steven; Mark, Bryan; Massaferro, Julieta; Montade, Vincent; Nazarova, Larisa; Novenko, Elena Y; Pařil, Petr; Pearson, Emma J.; Peros, Matthew; Pienitz, Reinhard; Plociennik, Mateusz; Porinchu, David F.; Potito, Aaron; Rees, Andrew B. H.; Reinemann, Scott; Roberts, Stephen J.; Rolland, Nicolas; Salonen, J. Sakari; Self, Angela E.; Seppä, Heikki; Shala, Shyhrete; St-Jacques, Jeannine-Marie; Stenni, Barbara; Syrykh, Liudmila; Tarrats, Pol; Taylor, Karen; van den Bos, Valerie; Velle, Gaute; Wahl, Eugene; Walker, Ian; Wilmhurst, Janet; Zhang, Enlou; Zhilich, Snezhana (2020)
  • Fülöp, Ludovic; Jussila, Vilho; Aapasuo, Riina Maria; Vuorinen, Tommi Antton Tapani; Mäntyniemi, Päivi Birgitta (2020)
    We propose a ground-motion prediction equation (GMPE) for probabilistic seismic hazard analysis of nuclear installations in Finland. We collected and archived the acceleration recordings of 77 earthquakes from seismic stations on very hard rock (VHR, i.e., the shear-wave velocity in the upper 30 m of the geological profile = 2800 m/s according to the definition used in the nuclear industry) in Finland and Sweden since 2006 and computed the corresponding response spectra important for engineering evaluation. We augmented the narrow magnitude range of the local data by a subset of VHR recordings of 33 earthquakes from the Next Generation Attenuation for Central and Eastern North America (CENA) (NGA-East) database, mainly from eastern Canada. We adapted the backbone curves of the G16 equation proposed by Graizer (2016) for CENA. After the calibration, we evaluated the accuracy of the median prediction and the random error. We conclude that the GMPE developed can be used for predicting ground motions in Fennoscandia. Because of compatibility with the original G16 backbone curve and comparisons with the NGA-East GMPEs, we estimate that the formulation proposed is valid on VHR over the range of 2
  • Warnock, Jonathan; Andren, Elinor; Juggins, Steve; Lewis, Jonathan; Ryves, David B.; Andren, Thomas; Weckstrom, Kaarina (2020)
    The large-scale shifts in the salinity of the Baltic Sea over the Holocene are well understood and have been comprehensively documented using sedimentary proxy records. More recent work has focused on understanding how past salinity fluctuations have affected other ecological parameters (e.g. primary productivity, nutrient content) of the Baltic basin, and salinity changes over key events and over short time scales are still not well understood. The International Ocean Drilling Program Expedition 347 cored the Baltic basin in order to collect basin-wide environmental records through a glacial-interglacial cycle. Site M0059 is located in the Little Belt between the Baltic Sea and the Atlantic Ocean. A composite splice section from Site M0059 was analysed at a decadal resolution to study changes in salinity, nutrient conditions and other surface water column parameters based on changes in diatom assemblages and on quantitative diatom-based salinity inferences. A mesotrophic slightly brackish assemblage is seen in the lowermost analysed depths, corresponding to 7800-7500 cal. a BP. An increase in salinity and nutrient content of the water column leads into a meso-eutrophic brackish phase. The observed salinity increase is rapid, lasting from 7500 to 7150 cal. a BP. Subsequently, the Little Belt becomes oligotrophic and is dominated by tychopelagic diatoms from c. 7100 to c. 3900 cal. a BP. This interval contains some of the highest salinities observed followed by diatom assemblages similar to those of the Northern Atlantic Ocean, composed primarily of cosmopolitan open oceanmarine diatoms. A return to tychopelagic productivity is seen from 3850 to 980 cal. a BP. Anthropogenic eutrophication is detected in the last 300 years of the record, which intensifies in the uppermost sediments. These results represent the first decadally resolved record in the region and provide new insight into the transition to a brackish basin and subsequent ecological development.