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  • Open Access English
    Authors: 
    Shevtsova, Iuliia; Herzschuh, Ulrike; Heim, Birgit; Kruse, Stefan;
    Publisher: Zenodo
    Project: EC | GlacialLegacy (772852)

    The model LAVESI (Kruse et al. 2016) was updated (Kruse 2023) and forced with historical and future climate forcing for 3 simulation repeats. This data set uses the data set of Kruse (2023) and applies a threshold of 0.68 km m-2 to differentiate forested areas according to the 2018 field inventories (Shevtsova et al., 2021). In this data set the total forest cover was summed up and the percent of total available areas is presented for the three climate forcings RCP 2.6, 4.5 and 8.5 and each complemented with a hypothetical cooling scenario from year 2300 CE onwards. The data provided is from years 1800, 1860, 1900, 1990, 2000 and in 5-year steps until 3000 CE and presents the mean over the three repeats of the sum of AGB of the whole study region: extent: 640008.2, 649998.2, 7475006, 7494716 m (xmin, xmax, ymin, ymax). Format: csv, with headers 1-year, Year in CE, 2-average percent forests cover for the study region, 3-upper and 4-lower, is the minimum and maximum value of the three simulations, 5-RCP, is the RCP scenario, 6-Cooling, contains in case of the cooling scenario the string “Cooling”. {"references": ["Stefan Kruse, Mareike Wieczorek, Florian Jeltsch and Ulrike Herzschuh (2016) Treeline dynamics in Siberia under changing climates as inferred from an individual-based model for Larix. Ecological Modelling, 338, 101\u2013121. http://dx.doi.org/10.1016/j.ecolmodel.2016.08.003 Additional data and results are available at https://doi.pangaea.de/10.1594/PANGAEA.863584", "Stefan Kruse (2023). StefanKruse/LAVESI: LAVESI-WIND with landscape (v2.0). Zenodo. https://doi.org/10.5281/zenodo.7505539", "Shevtsova, Iuliia, Herzschuh, Ulrike, Heim, Birgit, & Kruse, Stefan. (2023). Simulated above ground biomass of forests (larch) aggregated over the vicinity of the Ilirney lake system region, Chukotka, Russia [Data set]. Zenodo. https://doi.org/10.5281/zenodo.7505616", "Shevtsova I, Herzschuh U, Heim B, Schulte L, St\u00fcnzi S, Pestryakova LA, Zakharov ES, Kruse S: Recent above-ground biomass changes in central Chukotka (Russian Far East) using field sampling and Landsat satellite data. Biogeosciences, 18, 3343\u20133366, https://doi.org/10.5194/bg-18-3343-2021, 2021."]} This work has been supported by the German Federal Ministry of Education and Research (BMBF), which enabled the Russian-German research programme "Kohlenstoff im Permafrost KoPf" (grant no. 03F0764A), by the Initiative and Networking Fund of the Helmholtz Association and by the ERC consolidator grant Glacial Legacy of Ulrike Herzschuh (grant no. 772852).

  • Open Access English
    Authors: 
    Shevtsova, Iuliia; Herzschuh, Ulrike; Heim, Birgit; Kruse, Stefan;
    Publisher: Zenodo
    Project: EC | GlacialLegacy (772852)

    Forest density estimates visually determined by describing the amount of present trees satellite imagery from Esri basemap (Esri) at an area of ~30x30 m qualitatively for 6515 stratified sampled locations at an equal number of locations based on elevation, aspect and slope angle. The density was categorized ranging from 1: single trees to 4: dense tree stands present, and contains a 0: no trees present. Format: ESRI shapefile, points; projection UTM58N; extent: 642085.1, 654775.1, 7462263, 7492833 m (xmin, xmax, ymin, ymax) This work has been supported by the German Federal Ministry of Education and Research (BMBF), which enabled the Russian-German research programme "Kohlenstoff im Permafrost KoPf" (grant no. 03F0764A), by the Initiative and Networking Fund of the Helmholtz Association and by the ERC consolidator grant Glacial Legacy of Ulrike Herzschuh (grant no. 772852). {"references": ["Esri: \"High-resolution satellite and aerial imagery, typically within 3-5 years\" [basemap]. Scale Not Given. \"World Imagery\". https://www.arcgis.com/home/item.html?id=10df2279f9684e4a9f6a7f08febac2a9, Accession: 15 December 2020."]}

  • Open Access English
    Authors: 
    Shevtsova, Iuliia; Herzschuh, Ulrike; Heim, Birgit; Kruse, Stefan;
    Publisher: Zenodo
    Project: EC | GlacialLegacy (772852)

    The elevation was accessed for the area of interest in 90 m spatial resolution from the TanDEM-X 90 m digital elevation model (DEM) product (Krieger et al, 2013). Prior to spatial topographical parameters extraction, the DEM was resampled from the 90-m cell spacing to a 30-m resolution. The result was classified into 589 different possible combinations of elevation, slope angle, aspect. For the classification we used the possible combinations of elevation, slope, and aspect which were grouped into the following categories: Elevation: 0-400 m 400-450m 450-500m 500-600m 600-650m 650-700m 700-1000m 1000-1500m Slope: 0-2° 2-4° 4-6° 6-8° 8-10° 10-12° 12-16° 16-18° 18-20° 20-25° 25-50° Aspect: 0-45° 45-90° 90-135° 135-180° 180-225° 225-270° 270-315° 315-360° Format: Geotiff; projection UTM58N and 30x30 m tiles; extent: 642010.1, 654910.1, 7462218, 7492908 m (xmin, xmax, ymin, ymax) {"references": ["Krieger G, Zink M, Bachmann M, Br\u00e4utigam B, Schulze D, Martone M, Rizzoli P, Steinbrecher U, Antony JW, De Zan F, Hajnsek I, Papathanassiou K, Kugler F, Rodriguez Cassola M, Younis M, Baumgartner S, L\u00f3pez-Dekker P, Prats P, Moreira A: TanDEM-X: a radar interferometer with two formation-flying satellites. Acta Astronautica, 89, 83\u201398, https://doi.org/10.1016/j.actaastro.2013.03.008, 2013."]} This work has been supported by the German Federal Ministry of Education and Research (BMBF), which enabled the Russian-German research programme "Kohlenstoff im Permafrost KoPf" (grant no. 03F0764A), by the Initiative and Networking Fund of the Helmholtz Association and by the ERC consolidator grant Glacial Legacy of Ulrike Herzschuh (grant no. 772852).

  • English
    Authors: 
    Ferreira, Pedro; Ventura, Barbara; Barbieri, Andrea; Da Silva, José P.; Laia, César A. T.; Parola, A. Jorge; Basílio, Nuno;
    Publisher: SupraBank
    Project: FCT | RECI/BBB-BQB/0230/2012 (RECI/BBB-BQB/0230/2012), FCT | SFRH/BPD/84805/2012 (SFRH/BPD/84805/2012), EC | INFUSION (734834)

    Abstract The discovery of stimuli-responsive high affinity host–guest pairs with potential applications under biologically relevant conditions is a challenging goal. This work reports a high-affini...

  • English
    Authors: 
    Körner, Mareike; Brandt, Peter; Dengler, Marcus;
    Publisher: PANGAEA - Data Publisher for Earth & Environmental Science
    Project: EC | TRIATLAS (817578)

    The tropical Angolan upwelling system is a highly productive ecosystem with a distinct seasonal cycle in surface temperature and primary production. The lowest sea surface temperature, strongest cross-shore temperature gradient, and maximum productivity occur in austral winter when seasonally prevailing upwelling favorable winds are weakest. A multi cruise dataset of microstructure profiles collected between 2013 and 2022 in the tropical Angolan upwelling system was used to analyze the importance of mixing for cooling of the mixed layer. The data were collected during six cruises on board of the R/V Meteor. The results show that cooling due to turbulent heat fluxes at the base of the mixed layer is an important cooling term. This turbulent cooling, that is strongest in shallow shelf regions, is capable of explaining the observed negative cross-shore temperature gradient.

  • Open Access English
    Authors: 
    Waelbroeck, Claire; Tjiputra, Jerry; Guo, Chuncheng; Nisancioglu, Kerim H.; Jansen, Eystein; Vazquez Riveiros, Natalia; Toucanne, Samuel; Eynaud, Frédérique; Rossignol, Linda; Dewilde, Fabien; +3 more
    Project: EC | ICE2ICE (610055), EC | ACCLIMATE (339108)

    We combine consistently dated benthic carbon isotopic records distributed over the entire Atlantic Ocean with numerical simulations performed by a glacial configuration of the Norwegian Earth System Model with active ocean biogeochemistry, in order to interpret the observed Cibicides δ13C changes at the stadial-interstadial transition corresponding to the end of Heinrich Stadial 4 (HS4) in terms of ocean circulation and remineralization changes. We show that the marked increase in Cibicides δ13C observed at the end of HS4 between ~2000 and 4200 m in the Atlantic can be explained by changes in nutrient concentrations as simulated by the model in response to the halting of freshwater input in the high latitude glacial North Atlantic. Our model results show that this Cibicides δ13C signal is associated with changes in the ratio of southern-sourced (SSW) versus northern-sourced (NSW) water masses at the core sites, whereby SSW is replaced by NSW as a consequence of the resumption of deep water formation in the northern North Atlantic and Nordic Seas after the freshwater input is halted. Our results further suggest that the contribution of ocean circulation changes to this signal increases from ~40 % at 2000 m to ~80 % at 4000 m. Below ~4200 m, the model shows little ocean circulation change but an increase in remineralization across the transition marking the end of HS4. The simulated lower remineralization during stadials than interstadials is particularly pronounced in deep subantarctic sites, in agreement with the decrease in the export production of carbon to the deep Southern Ocean during stadials found in previous studies.

  • Open Access English
    Authors: 
    Romero-Alvarez, Johana; Lupaşcu, Aurelia; Lowe, Douglas; Badia, Alba; Acher-Nicholls, Scott; Dorling, Steve R.; Reeves, Claire E.; Butler, Tim;
    Project: EC | ASIBIA (616938)

    Tropospheric ozone (O3) concentrations depend on a combination of hemispheric, regional, and local-scale processes. Estimates of how much O3 is produced locally vs. transported from further afield are essential in air quality management and regulatory policies. Here, a tagged-ozone mechanism within the Weather Research and Forecasting model coupled with chemistry (WRF-Chem) is used to quantify the contributions to surface O3 in the UK from anthropogenic nitrogen oxide (NOx) emissions from inside and outside the UK during May–August 2015. The contribution of the different source regions to three regulatory O3 metrics is also examined. It is shown that model simulations predict the concentration and spatial distribution of surface O3 with a domain-wide mean bias of −3.7 ppbv. Anthropogenic NOx emissions from the UK and Europe account for 13 % and 16 %, respectively, of the monthly mean surface O3 in the UK, as the majority (71 %) of O3 originates from the hemispheric background. Hemispheric O3 contributes the most to concentrations in the north and the west of the UK with peaks in May, whereas European and UK contributions are most significant in the east, south-east, and London, i.e. the UK's most populated areas, intensifying towards June and July. Moreover, O3 from European sources is generally transported to the UK rather than produced in situ. It is demonstrated that more stringent emission controls over continental Europe, particularly in western Europe, would be necessary to improve the health-related metric MDA8 O3 above 50 and 60 ppbv. Emission controls over larger areas, such as the Northern Hemisphere, are instead required to lessen the impacts on ecosystems as quantified by the AOT40 metric.

  • Open Access English
    Authors: 
    Galgani, Luisa; Tzempelikou, Eleni; Kalantzi, Ioanna; Tsiola, Anastasia; Tsapakis, Manolis; Paraskevi, Pitta; Esposito, Chiara; Tsotskou, Anastasia; Magiopoulos, Iordanis; Benavides, Roberto; +2 more
    Publisher: Zenodo
    Project: EC | POSEIDOMM (702747)

    Microplastics are substrates for microbial activity and can influence biomass production. This has potentially important implications in the sea-surface microlayer, the marine boundary layer that controls gas exchange with the atmosphere and where biologically produced organic compounds can accumulate. In the present study, we used six large scale mesocosms to simulate future ocean scenarios of high plastic concentration. Each mesocosm was filled with 3 m3 of seawater from the oligotrophic Sea of Crete, in the Eastern Mediterranean Sea. A known amount of standard polystyrene microbeads of 30 μm diameter was added to three replicate mesocosms, while maintaining the remaining three as plastic-free controls. Over the course of a 12-day experiment, we explored microbial organic matter dynamics in the sea-surface microlayer in the presence and absence of microplastic contamination of the underlying water. Our study shows that microplastics increased both biomass production and enrichment of carbohydrate-like and proteinaceous marine gel compounds in the sea-surface microlayer. Importantly, this resulted in a 3 % reduction in the concentration of dissolved CO2 in the underlying water. This reduction was associated to both direct and indirect impacts of microplastic pollution on the uptake of CO2 within the marine carbon cycle, by modifying the biogenic composition of the sea's boundary layer with the atmosphere. for information: luisa.galgani@icloud.com; luisa.galgani@unisi.it; lgalgani@geomar.de

  • Open Access English
    Authors: 
    Kjær, Helle Astrid; Zens, Patrick; Black, Samuel; Lund, Kasper Holst; Svensson, Anders; Vallelonga, Paul;
    Project: EC | ICE2ICE (610055)

    Greenland ice cores provide information about past climate. Few impurity records covering the past 2 decades exist from Greenland. Here we present results from six firn cores obtained during a 426 km long northern Greenland traverse made in 2015 between the NEEM and the EGRIP deep-drilling stations situated on the western side and eastern side of the Greenland ice sheet, respectively. The cores (9 to 14 m long) are analyzed for chemical impurities and cover time spans of 18 to 53 years (±3 years) depending on local snow accumulation that decreases from west to east. The high temporal resolution allows for annual layers and seasons to be resolved. Insoluble dust, ammonium, and calcium concentrations in the six firn cores overlap, and the seasonal cycles are also similar in timing and magnitude across sites, while peroxide (H2O2) and conductivity both have spatial variations, H2O2 driven by the accumulation pattern, and conductivity likely influenced by sea salt. Overall, we determine a rather constant dust flux over the period, but in the data from recent years (1998–2015) we identify an increase in large dust particles that we ascribe to an activation of local Greenland sources. We observe an expected increase in acidity and conductivity in the mid-1970s as a result of anthropogenic emissions, followed by a decrease due to mitigation. Several volcanic horizons identified in the conductivity and acidity records can be associated with eruptions in Iceland and in the Barents Sea region. From a composite ammonium record we obtain a robust forest fire proxy associated primarily with Canadian forest fires (R=0.49).

  • Open Access English
    Authors: 
    Droste, Elise S.; Hoppema, Mario; González-Dávila, Melchor; Santana-Casiano, Juana Magdalena; Queste, Bastien Y.; Dall'Olmo, Giorgio; Venables, Hugh J.; Rohardt, Gerd; Ossebaar, Sharyn; Schuller, Daniel; +2 more
    Project: EC | CARBOCHANGE (264879)

    Tides significantly affect polar coastlines by modulating ice shelf melt and modifying shelf water properties through transport and mixing. However, the effect of tides on the marine carbonate chemistry in such regions, especially around Antarctica, remains largely unexplored. We address this topic with two case studies in a coastal polynya in the south-eastern Weddell Sea, neighbouring the Ekström Ice Shelf. The case studies were conducted in January 2015 (PS89) and January 2019 (PS117), capturing semi-diurnal oscillations in the water column. These are pronounced in both physical and biogeochemical variables for PS89. During rising tide, advection of sea ice meltwater from the north-east created a fresher, warmer, and more deeply mixed water column with lower dissolved inorganic carbon (DIC) and total alkalinity (TA) content. During ebbing tide, water from underneath the ice shelf decreased the polynya's temperature, increased the DIC and TA content, and created a more stratified water column. The variability during the PS117 case study was much smaller, as it had less sea ice meltwater input during rising tide and was better mixed with sub-ice shelf water. The contrasts in the variability between the two case studies could be wind and sea ice driven, and they underline the complexity and highly dynamic nature of the system. The variability in the polynya induced by the tides results in an air–sea CO2 flux that can range between a strong sink (−24 mmol m−2 d−1) and a small source (3 mmol m−2 d−1) on a semi-diurnal timescale. If the variability induced by tides is not taken into account, there is a potential risk of overestimating the polynya's CO2 uptake by 67 % or underestimating it by 73 %, compared to the average flux determined over several days. Depending on the timing of limited sampling, the polynya may appear to be a source or a sink of CO2. Given the disproportionate influence of polynyas on heat and carbon exchange in polar oceans, we recommend future studies around the Antarctic and Arctic coastlines to consider the timing of tidal currents in their sampling strategies and analyses. This will help constrain variability in oceanographic measurements and avoid potential biases in our understanding of these highly complex systems.

Advanced search in Research products
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The following results are related to European Marine Science. Are you interested to view more results? Visit OpenAIRE - Explore.
3,615 Research products, page 1 of 362
  • Open Access English
    Authors: 
    Shevtsova, Iuliia; Herzschuh, Ulrike; Heim, Birgit; Kruse, Stefan;
    Publisher: Zenodo
    Project: EC | GlacialLegacy (772852)

    The model LAVESI (Kruse et al. 2016) was updated (Kruse 2023) and forced with historical and future climate forcing for 3 simulation repeats. This data set uses the data set of Kruse (2023) and applies a threshold of 0.68 km m-2 to differentiate forested areas according to the 2018 field inventories (Shevtsova et al., 2021). In this data set the total forest cover was summed up and the percent of total available areas is presented for the three climate forcings RCP 2.6, 4.5 and 8.5 and each complemented with a hypothetical cooling scenario from year 2300 CE onwards. The data provided is from years 1800, 1860, 1900, 1990, 2000 and in 5-year steps until 3000 CE and presents the mean over the three repeats of the sum of AGB of the whole study region: extent: 640008.2, 649998.2, 7475006, 7494716 m (xmin, xmax, ymin, ymax). Format: csv, with headers 1-year, Year in CE, 2-average percent forests cover for the study region, 3-upper and 4-lower, is the minimum and maximum value of the three simulations, 5-RCP, is the RCP scenario, 6-Cooling, contains in case of the cooling scenario the string “Cooling”. {"references": ["Stefan Kruse, Mareike Wieczorek, Florian Jeltsch and Ulrike Herzschuh (2016) Treeline dynamics in Siberia under changing climates as inferred from an individual-based model for Larix. Ecological Modelling, 338, 101\u2013121. http://dx.doi.org/10.1016/j.ecolmodel.2016.08.003 Additional data and results are available at https://doi.pangaea.de/10.1594/PANGAEA.863584", "Stefan Kruse (2023). StefanKruse/LAVESI: LAVESI-WIND with landscape (v2.0). Zenodo. https://doi.org/10.5281/zenodo.7505539", "Shevtsova, Iuliia, Herzschuh, Ulrike, Heim, Birgit, & Kruse, Stefan. (2023). Simulated above ground biomass of forests (larch) aggregated over the vicinity of the Ilirney lake system region, Chukotka, Russia [Data set]. Zenodo. https://doi.org/10.5281/zenodo.7505616", "Shevtsova I, Herzschuh U, Heim B, Schulte L, St\u00fcnzi S, Pestryakova LA, Zakharov ES, Kruse S: Recent above-ground biomass changes in central Chukotka (Russian Far East) using field sampling and Landsat satellite data. Biogeosciences, 18, 3343\u20133366, https://doi.org/10.5194/bg-18-3343-2021, 2021."]} This work has been supported by the German Federal Ministry of Education and Research (BMBF), which enabled the Russian-German research programme "Kohlenstoff im Permafrost KoPf" (grant no. 03F0764A), by the Initiative and Networking Fund of the Helmholtz Association and by the ERC consolidator grant Glacial Legacy of Ulrike Herzschuh (grant no. 772852).

  • Open Access English
    Authors: 
    Shevtsova, Iuliia; Herzschuh, Ulrike; Heim, Birgit; Kruse, Stefan;
    Publisher: Zenodo
    Project: EC | GlacialLegacy (772852)

    Forest density estimates visually determined by describing the amount of present trees satellite imagery from Esri basemap (Esri) at an area of ~30x30 m qualitatively for 6515 stratified sampled locations at an equal number of locations based on elevation, aspect and slope angle. The density was categorized ranging from 1: single trees to 4: dense tree stands present, and contains a 0: no trees present. Format: ESRI shapefile, points; projection UTM58N; extent: 642085.1, 654775.1, 7462263, 7492833 m (xmin, xmax, ymin, ymax) This work has been supported by the German Federal Ministry of Education and Research (BMBF), which enabled the Russian-German research programme "Kohlenstoff im Permafrost KoPf" (grant no. 03F0764A), by the Initiative and Networking Fund of the Helmholtz Association and by the ERC consolidator grant Glacial Legacy of Ulrike Herzschuh (grant no. 772852). {"references": ["Esri: \"High-resolution satellite and aerial imagery, typically within 3-5 years\" [basemap]. Scale Not Given. \"World Imagery\". https://www.arcgis.com/home/item.html?id=10df2279f9684e4a9f6a7f08febac2a9, Accession: 15 December 2020."]}

  • Open Access English
    Authors: 
    Shevtsova, Iuliia; Herzschuh, Ulrike; Heim, Birgit; Kruse, Stefan;
    Publisher: Zenodo
    Project: EC | GlacialLegacy (772852)

    The elevation was accessed for the area of interest in 90 m spatial resolution from the TanDEM-X 90 m digital elevation model (DEM) product (Krieger et al, 2013). Prior to spatial topographical parameters extraction, the DEM was resampled from the 90-m cell spacing to a 30-m resolution. The result was classified into 589 different possible combinations of elevation, slope angle, aspect. For the classification we used the possible combinations of elevation, slope, and aspect which were grouped into the following categories: Elevation: 0-400 m 400-450m 450-500m 500-600m 600-650m 650-700m 700-1000m 1000-1500m Slope: 0-2° 2-4° 4-6° 6-8° 8-10° 10-12° 12-16° 16-18° 18-20° 20-25° 25-50° Aspect: 0-45° 45-90° 90-135° 135-180° 180-225° 225-270° 270-315° 315-360° Format: Geotiff; projection UTM58N and 30x30 m tiles; extent: 642010.1, 654910.1, 7462218, 7492908 m (xmin, xmax, ymin, ymax) {"references": ["Krieger G, Zink M, Bachmann M, Br\u00e4utigam B, Schulze D, Martone M, Rizzoli P, Steinbrecher U, Antony JW, De Zan F, Hajnsek I, Papathanassiou K, Kugler F, Rodriguez Cassola M, Younis M, Baumgartner S, L\u00f3pez-Dekker P, Prats P, Moreira A: TanDEM-X: a radar interferometer with two formation-flying satellites. Acta Astronautica, 89, 83\u201398, https://doi.org/10.1016/j.actaastro.2013.03.008, 2013."]} This work has been supported by the German Federal Ministry of Education and Research (BMBF), which enabled the Russian-German research programme "Kohlenstoff im Permafrost KoPf" (grant no. 03F0764A), by the Initiative and Networking Fund of the Helmholtz Association and by the ERC consolidator grant Glacial Legacy of Ulrike Herzschuh (grant no. 772852).

  • English
    Authors: 
    Ferreira, Pedro; Ventura, Barbara; Barbieri, Andrea; Da Silva, José P.; Laia, César A. T.; Parola, A. Jorge; Basílio, Nuno;
    Publisher: SupraBank
    Project: FCT | RECI/BBB-BQB/0230/2012 (RECI/BBB-BQB/0230/2012), FCT | SFRH/BPD/84805/2012 (SFRH/BPD/84805/2012), EC | INFUSION (734834)

    Abstract The discovery of stimuli-responsive high affinity host–guest pairs with potential applications under biologically relevant conditions is a challenging goal. This work reports a high-affini...

  • English
    Authors: 
    Körner, Mareike; Brandt, Peter; Dengler, Marcus;
    Publisher: PANGAEA - Data Publisher for Earth & Environmental Science
    Project: EC | TRIATLAS (817578)

    The tropical Angolan upwelling system is a highly productive ecosystem with a distinct seasonal cycle in surface temperature and primary production. The lowest sea surface temperature, strongest cross-shore temperature gradient, and maximum productivity occur in austral winter when seasonally prevailing upwelling favorable winds are weakest. A multi cruise dataset of microstructure profiles collected between 2013 and 2022 in the tropical Angolan upwelling system was used to analyze the importance of mixing for cooling of the mixed layer. The data were collected during six cruises on board of the R/V Meteor. The results show that cooling due to turbulent heat fluxes at the base of the mixed layer is an important cooling term. This turbulent cooling, that is strongest in shallow shelf regions, is capable of explaining the observed negative cross-shore temperature gradient.

  • Open Access English
    Authors: 
    Waelbroeck, Claire; Tjiputra, Jerry; Guo, Chuncheng; Nisancioglu, Kerim H.; Jansen, Eystein; Vazquez Riveiros, Natalia; Toucanne, Samuel; Eynaud, Frédérique; Rossignol, Linda; Dewilde, Fabien; +3 more
    Project: EC | ICE2ICE (610055), EC | ACCLIMATE (339108)

    We combine consistently dated benthic carbon isotopic records distributed over the entire Atlantic Ocean with numerical simulations performed by a glacial configuration of the Norwegian Earth System Model with active ocean biogeochemistry, in order to interpret the observed Cibicides δ13C changes at the stadial-interstadial transition corresponding to the end of Heinrich Stadial 4 (HS4) in terms of ocean circulation and remineralization changes. We show that the marked increase in Cibicides δ13C observed at the end of HS4 between ~2000 and 4200 m in the Atlantic can be explained by changes in nutrient concentrations as simulated by the model in response to the halting of freshwater input in the high latitude glacial North Atlantic. Our model results show that this Cibicides δ13C signal is associated with changes in the ratio of southern-sourced (SSW) versus northern-sourced (NSW) water masses at the core sites, whereby SSW is replaced by NSW as a consequence of the resumption of deep water formation in the northern North Atlantic and Nordic Seas after the freshwater input is halted. Our results further suggest that the contribution of ocean circulation changes to this signal increases from ~40 % at 2000 m to ~80 % at 4000 m. Below ~4200 m, the model shows little ocean circulation change but an increase in remineralization across the transition marking the end of HS4. The simulated lower remineralization during stadials than interstadials is particularly pronounced in deep subantarctic sites, in agreement with the decrease in the export production of carbon to the deep Southern Ocean during stadials found in previous studies.

  • Open Access English
    Authors: 
    Romero-Alvarez, Johana; Lupaşcu, Aurelia; Lowe, Douglas; Badia, Alba; Acher-Nicholls, Scott; Dorling, Steve R.; Reeves, Claire E.; Butler, Tim;
    Project: EC | ASIBIA (616938)

    Tropospheric ozone (O3) concentrations depend on a combination of hemispheric, regional, and local-scale processes. Estimates of how much O3 is produced locally vs. transported from further afield are essential in air quality management and regulatory policies. Here, a tagged-ozone mechanism within the Weather Research and Forecasting model coupled with chemistry (WRF-Chem) is used to quantify the contributions to surface O3 in the UK from anthropogenic nitrogen oxide (NOx) emissions from inside and outside the UK during May–August 2015. The contribution of the different source regions to three regulatory O3 metrics is also examined. It is shown that model simulations predict the concentration and spatial distribution of surface O3 with a domain-wide mean bias of −3.7 ppbv. Anthropogenic NOx emissions from the UK and Europe account for 13 % and 16 %, respectively, of the monthly mean surface O3 in the UK, as the majority (71 %) of O3 originates from the hemispheric background. Hemispheric O3 contributes the most to concentrations in the north and the west of the UK with peaks in May, whereas European and UK contributions are most significant in the east, south-east, and London, i.e. the UK's most populated areas, intensifying towards June and July. Moreover, O3 from European sources is generally transported to the UK rather than produced in situ. It is demonstrated that more stringent emission controls over continental Europe, particularly in western Europe, would be necessary to improve the health-related metric MDA8 O3 above 50 and 60 ppbv. Emission controls over larger areas, such as the Northern Hemisphere, are instead required to lessen the impacts on ecosystems as quantified by the AOT40 metric.

  • Open Access English
    Authors: 
    Galgani, Luisa; Tzempelikou, Eleni; Kalantzi, Ioanna; Tsiola, Anastasia; Tsapakis, Manolis; Paraskevi, Pitta; Esposito, Chiara; Tsotskou, Anastasia; Magiopoulos, Iordanis; Benavides, Roberto; +2 more
    Publisher: Zenodo
    Project: EC | POSEIDOMM (702747)

    Microplastics are substrates for microbial activity and can influence biomass production. This has potentially important implications in the sea-surface microlayer, the marine boundary layer that controls gas exchange with the atmosphere and where biologically produced organic compounds can accumulate. In the present study, we used six large scale mesocosms to simulate future ocean scenarios of high plastic concentration. Each mesocosm was filled with 3 m3 of seawater from the oligotrophic Sea of Crete, in the Eastern Mediterranean Sea. A known amount of standard polystyrene microbeads of 30 μm diameter was added to three replicate mesocosms, while maintaining the remaining three as plastic-free controls. Over the course of a 12-day experiment, we explored microbial organic matter dynamics in the sea-surface microlayer in the presence and absence of microplastic contamination of the underlying water. Our study shows that microplastics increased both biomass production and enrichment of carbohydrate-like and proteinaceous marine gel compounds in the sea-surface microlayer. Importantly, this resulted in a 3 % reduction in the concentration of dissolved CO2 in the underlying water. This reduction was associated to both direct and indirect impacts of microplastic pollution on the uptake of CO2 within the marine carbon cycle, by modifying the biogenic composition of the sea's boundary layer with the atmosphere. for information: luisa.galgani@icloud.com; luisa.galgani@unisi.it; lgalgani@geomar.de

  • Open Access English
    Authors: 
    Kjær, Helle Astrid; Zens, Patrick; Black, Samuel; Lund, Kasper Holst; Svensson, Anders; Vallelonga, Paul;
    Project: EC | ICE2ICE (610055)

    Greenland ice cores provide information about past climate. Few impurity records covering the past 2 decades exist from Greenland. Here we present results from six firn cores obtained during a 426 km long northern Greenland traverse made in 2015 between the NEEM and the EGRIP deep-drilling stations situated on the western side and eastern side of the Greenland ice sheet, respectively. The cores (9 to 14 m long) are analyzed for chemical impurities and cover time spans of 18 to 53 years (±3 years) depending on local snow accumulation that decreases from west to east. The high temporal resolution allows for annual layers and seasons to be resolved. Insoluble dust, ammonium, and calcium concentrations in the six firn cores overlap, and the seasonal cycles are also similar in timing and magnitude across sites, while peroxide (H2O2) and conductivity both have spatial variations, H2O2 driven by the accumulation pattern, and conductivity likely influenced by sea salt. Overall, we determine a rather constant dust flux over the period, but in the data from recent years (1998–2015) we identify an increase in large dust particles that we ascribe to an activation of local Greenland sources. We observe an expected increase in acidity and conductivity in the mid-1970s as a result of anthropogenic emissions, followed by a decrease due to mitigation. Several volcanic horizons identified in the conductivity and acidity records can be associated with eruptions in Iceland and in the Barents Sea region. From a composite ammonium record we obtain a robust forest fire proxy associated primarily with Canadian forest fires (R=0.49).

  • Open Access English
    Authors: 
    Droste, Elise S.; Hoppema, Mario; González-Dávila, Melchor; Santana-Casiano, Juana Magdalena; Queste, Bastien Y.; Dall'Olmo, Giorgio; Venables, Hugh J.; Rohardt, Gerd; Ossebaar, Sharyn; Schuller, Daniel; +2 more
    Project: EC | CARBOCHANGE (264879)

    Tides significantly affect polar coastlines by modulating ice shelf melt and modifying shelf water properties through transport and mixing. However, the effect of tides on the marine carbonate chemistry in such regions, especially around Antarctica, remains largely unexplored. We address this topic with two case studies in a coastal polynya in the south-eastern Weddell Sea, neighbouring the Ekström Ice Shelf. The case studies were conducted in January 2015 (PS89) and January 2019 (PS117), capturing semi-diurnal oscillations in the water column. These are pronounced in both physical and biogeochemical variables for PS89. During rising tide, advection of sea ice meltwater from the north-east created a fresher, warmer, and more deeply mixed water column with lower dissolved inorganic carbon (DIC) and total alkalinity (TA) content. During ebbing tide, water from underneath the ice shelf decreased the polynya's temperature, increased the DIC and TA content, and created a more stratified water column. The variability during the PS117 case study was much smaller, as it had less sea ice meltwater input during rising tide and was better mixed with sub-ice shelf water. The contrasts in the variability between the two case studies could be wind and sea ice driven, and they underline the complexity and highly dynamic nature of the system. The variability in the polynya induced by the tides results in an air–sea CO2 flux that can range between a strong sink (−24 mmol m−2 d−1) and a small source (3 mmol m−2 d−1) on a semi-diurnal timescale. If the variability induced by tides is not taken into account, there is a potential risk of overestimating the polynya's CO2 uptake by 67 % or underestimating it by 73 %, compared to the average flux determined over several days. Depending on the timing of limited sampling, the polynya may appear to be a source or a sink of CO2. Given the disproportionate influence of polynyas on heat and carbon exchange in polar oceans, we recommend future studies around the Antarctic and Arctic coastlines to consider the timing of tidal currents in their sampling strategies and analyses. This will help constrain variability in oceanographic measurements and avoid potential biases in our understanding of these highly complex systems.