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  • 1
    Online Resource
    Online Resource
    Warm and sensitive Paleocene-Eocene climate (2009)
    Hamburg : Max-Planck-Inst. für Meteorologie
    Details Availability
    Keywords: Hochschulschrift ; Forschungsbericht ; Paläogen ; Paläoklima
    Type of Medium: Online Resource
    Pages: Online-Ressource (119 S., 16,7 MB)
    Series Statement: Berichte zur Erdsystemforschung 70
    URL: http://www.mpimet.mpg.de/fileadmin/publikationen/Reports/WEB_BzE_70.pdf
    URL: https://edocs.tib.eu/files/e01fn13/631242074.pdf
    URL: http://epub.sub.uni-hamburg.de/epub/volltexte/2015/41822/
    URL: https://edocs.tib.eu/files/e01fn13/631242074l.pdf
    Language: English
    Note: Zsfassung in engl. Sprache , Zugl.: Hamburg, Univ., Diss., 2009 , Systemvoraussetzungen: Acrobat reader.
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  • 2
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    KOSMOS 2018 Gran Canaria mesocosm study: particle flux data from sediment trap (2021)
    PANGAEA
    Details
    Publication Date: 2024-03-06
    Description: The data set compiles sinking flux data collected during a KOSMOS mesocosm experiment carried out in the frame work of the Ocean Artificial Upwelling project. The experiment was performed in the North-East Atlantic Ocean off the coast of Gran Canaria in autumn 2018 and lasted for 39 days. In this study we investigated the effect of different intensities of artificial upwelling combined with two upwelling modes (recurring additions versus one singular addition) on POC export and its potential transfer efficiency to depth. The data set includes the amounts of surface water that were exchanged with nutrient-rich deep water (from ~300 m depth). It also contains particle flux data, i.e. POC flux, PON flux, BSi flux and the corresponding C:N and C:Si ratios, as well as the carbon-specific remineralization rates, sinking velocities, porosities and remineralization length scales of sinking particles.
    Keywords: artificial upwelling; Biogenic silica, flux per day; Canarias Sea; Carbon, organic, particulate, flux, cumulative; Carbon, organic, particulate, flux per day; Carbon/Nitrogen ratio; Carbon/Silicon ratio; carbon sequestration; DATE/TIME; Deep water exchange, total; DEPTH, water, experiment; Event label; Experiment day; export flux; KOSMOS_2018; KOSMOS_2018_Mesocosm-M1; KOSMOS_2018_Mesocosm-M2; KOSMOS_2018_Mesocosm-M3; KOSMOS_2018_Mesocosm-M4; KOSMOS_2018_Mesocosm-M5; KOSMOS_2018_Mesocosm-M6; KOSMOS_2018_Mesocosm-M7; KOSMOS_2018_Mesocosm-M8; KOSMOS_2018_Mesocosm-M9; KOSMOS Gran Canaria; MESO; Mesocosm experiment; Mesocosm label; mesocosm study; Nitrogen, organic, particulate, flux, cumulative; Nitrogen, organic, particulate, flux per day; Ocean Artificial Upwelling; Ocean-artUp; Particle porosity; particle properties; Remineralisation length scale; Remineralisation rate of carbon per day; remineralization depth; remineralization rate; sinking velocity; Sinking velocity; Treatment
    Type: Dataset
    Format: text/tab-separated-values, 2473 data points
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    DATA PANGAEA
  • 3
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    KOSMOS 2018 Gran Canaria mesocosm study: water column biogeochemistry (2021)
    PANGAEA
    Details
    Publication Date: 2024-03-06
    Description: The data set compiles biogeochemical water column collected during a KOSMOS mesocosm experiment carried out in the frame work of the Ocean Artificial Upwelling project. The experiment was performed in the North-East Atlantic Ocean off the coast of Gran Canaria in autumn 2018 and lasted for 39 days. In this study we investigated the effect of different intensities of artificial upwelling combined with two upwelling modes (recurring additions versus one singular addition) on POC export and its potential transfer efficiency to depth. The data set includes the amounts of surface water that were exchanged with nutrient-rich deep water (from ~300 m depth), primary production and chlorophyll a, elemental composition of suspended particulate matter (POC, PON, C:N) and prokaryotic heterotrophic production.
    Keywords: artificial upwelling; Canarias Sea; Carbon, organic, particulate; Carbon/Nitrogen ratio; carbon sequestration; Chlorophyll a; DATE/TIME; Deep water exchange, total; DEPTH, water, experiment; Event label; Experiment day; export flux; KOSMOS_2018; KOSMOS_2018_Mesocosm-M1; KOSMOS_2018_Mesocosm-M2; KOSMOS_2018_Mesocosm-M3; KOSMOS_2018_Mesocosm-M4; KOSMOS_2018_Mesocosm-M5; KOSMOS_2018_Mesocosm-M6; KOSMOS_2018_Mesocosm-M7; KOSMOS_2018_Mesocosm-M8; KOSMOS_2018_Mesocosm-M9; KOSMOS Gran Canaria; MESO; Mesocosm experiment; Mesocosm label; mesocosm study; Nitrogen, organic, particulate; Ocean Artificial Upwelling; Ocean-artUp; particle properties; Primary production; Primary production, cumulative; Prokaryotic heterotrophic production; remineralization depth; remineralization rate; sinking velocity; Treatment
    Type: Dataset
    Format: text/tab-separated-values, 2094 data points
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    DATA PANGAEA
  • 4
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    Simulating Marine Isotope Stage 7 with a coupled climate–ice sheet model (2020)
    Copernicus Publications (EGU)
    Details
    Publication Date: 2023-02-08
    Description: It is widely accepted that orbital variations are responsible for the generation of glacial cycles during the late Pleistocene. However, the relative contributions of the orbital forcing compared to CO2 variations and other feedback mechanisms causing the waxing and waning of ice sheets have not been fully understood. Testing theories of ice ages beyond statistical inferences, requires numerical modeling experiments that capture key features of glacial transitions. Here, we focus on the glacial buildup from Marine Isotope Stage (MIS) 7 to 6 covering the period from 240 to 170 ka (ka: thousand years before present). This transition from interglacial to glacial conditions includes one of the fastest Pleistocene glaciation–deglaciation events, which occurred during MIS 7e–7d–7c (236–218 ka). Using a newly developed three-dimensional coupled atmosphere–ocean–vegetation–ice sheet model (LOVECLIP), we simulate the transient evolution of Northern Hemisphere and Southern Hemisphere ice sheets during the MIS 7–6 period in response to orbital and greenhouse gas forcing. For a range of model parameters, the simulations capture the evolution of global ice volume well within the range of reconstructions. Over the MIS 7–6 period, it is demonstrated that glacial inceptions are more sensitive to orbital variations, whereas terminations from deep glacial conditions need both orbital and greenhouse gas forcings to work in unison. For some parameter values, the coupled model also exhibits a critical North American ice sheet configuration, beyond which a stationary-wave–ice-sheet topography feedback can trigger an unabated and unrealistic ice sheet growth. The strong parameter sensitivity found in this study originates from the fact that delicate mass imbalances, as well as errors, are integrated during a transient simulation for thousands of years. This poses a general challenge for transient coupled climate–ice sheet modeling, with such coupled paleo-simulations providing opportunities to constrain such parameters.
    Type: Article , PeerReviewed
    Format: text
    Format: text
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 5
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    Effect of Intensity and Mode of Artificial Upwelling on Particle Flux and Carbon Export (2021)
    Frontiers
    Details
    Publication Date: 2024-02-07
    Description: Reduction of anthropogenic CO2 emissions alone will not sufficiently restrict global warming and enable the 1.5°C goal of the Paris agreement to be met. To effectively counteract climate change, measures to actively remove carbon dioxide from the atmosphere are required. Artificial upwelling has been proposed as one such carbon dioxide removal technique. By fueling primary productivity in the surface ocean with nutrient-rich deep water, it could potentially enhance downward fluxes of particulate organic carbon (POC) and carbon sequestration. In this study we investigated the effect of different intensities of artificial upwelling combined with two upwelling modes (recurring additions vs. one singular addition) on POC export, sinking matter stoichiometry and remineralization depth. We carried out a 39 day-long mesocosm experiment in the subtropical North Atlantic, where we fertilized oligotrophic surface waters with different amounts of deep water. The total nutrient inputs ranged from 1.6 to 11.0 μmol NO3– L–1. We found that on the one hand POC export under artificial upwelling more than doubled, and the molar C:N ratios of sinking organic matter increased from values around Redfield (6.6) to ∼8–13, which is beneficial for potential carbon dioxide removal. On the other hand, sinking matter was remineralized at faster rates and showed lower sinking velocities, which led to shallower remineralization depths. Particle properties were more favorable for deep carbon export in the recurring upwelling mode, while in the singular mode the C:N increase of sinking matter was more pronounced. In both upwelling modes roughly half of the produced organic carbon was retained in the water column until the end of the experiment. This suggests that the plankton communities were still in the process of adjustment, possibly due to the different response times of producers and consumers. There is thus a need for studies with longer experimental durations to quantify the responses of fully adjusted communities. Finally, our results revealed that artificial upwelling affects a variety of sinking particle properties, and that the intensity and mode with which it is applied control the strength of the effects
    Type: Article , PeerReviewed , info:eu-repo/semantics/article
    Format: text
    Format: text
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 6
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    Respiration rate scales inversely with sinking speed of settling marine aggregates (2023)
    Public Library of Science
    Details
    Publication Date: 2024-02-07
    Description: Sinking marine aggregates have been studied for a long time to understand their role in carbon sequestration. Traditionally, sinking speed and respiration rates have been treated as independent variables, but two recent papers suggest that there is a connection albeit in contrasting directions. Here we collected recently formed (〈2 days old) aggregates from sediment traps mounted underneath mesocosms during two different experiments. The mesocosms were moored off Gran Canaria, Spain (~ 27.9 N; 15.4 E) in a coastal, sub-tropical and oligotrophic ecosystem. We determined the respiration rates of organisms (mainly heterotrophic prokaryotes) attached to aggregates sinking at different velocities. The average respiration rate of fast sinking aggregates (〉100 m d-1) was 0.12 d-1 ± 0.08 d-1 (SD). Slower sinking aggregates (〈50 m d-1) had on average higher (p 〈0.001) and more variable respiration rates (average 0.31 d-1 ± 0.16 d-1, SD). There was evidence that slower sinking aggregates had higher porosity than fast sinking aggregates, and we hypothesize that higher porosity increase the settlement area for bacteria and the respiration rate. These findings provide insights into the efficiency of the biological carbon pump and help resolve the apparent discrepancy in the recent studies of the correlation between respiration and sinking speed. © 2023 Spilling et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
    Type: Article , PeerReviewed , info:eu-repo/semantics/article
    Format: text
    Format: other
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 7
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    The Earth system model CLIMBER-X v1.0 – Part 2: The global carbon cycle (2023)
    Copernicus Publications (EGU)
    Details
    Publication Date: 2024-02-07
    Description: The carbon cycle component of the newly developed Earth System Model of intermediate complexity CLIMBER-X is presented. The model represents the cycling of carbon through atmosphere, vegetation, soils, seawater and marine sediments. Exchanges of carbon with geological reservoirs occur through sediment burial, rock weathering and volcanic degassing. The state-of-the-art HAMOCC6 model is employed to simulate ocean biogeochemistry and marine sediments processes. The land model PALADYN simulates the processes related to vegetation and soil carbon dynamics, including permafrost and peatlands. The dust cycle in the model allows for an interactive determination of the input of the micro-nutrient iron into the ocean. A rock weathering scheme is implemented into the model, with the weathering rate depending on lithology, runoff and soil temperature. CLIMBER-X includes a simple representation of the methane cycle, with explicitly modelled natural emissions from land and the assumption of a constant residence time of CH4 in the atmosphere. Carbon isotopes 13C and 14C are tracked through all model compartments and provide a useful diagnostic for model-data comparison. A comprehensive evaluation of the model performance for present–day and the historical period shows that CLIMBER-X is capable of realistically reproducing the historical evolution of atmospheric CO2 and CH4, but also the spatial distribution of carbon on land and the 3D structure of biogeochemical ocean tracers. The analysis of model performance is complemented by an assessment of carbon cycle feedbacks and model sensitivities compared to state-of-the-art CMIP6 models. Enabling interactive carbon cycle in CLIMBER-X results in a relatively minor slow-down of model computational performance by ~20 %, compared to a throughput of ~10,000 simulation years per day on a single node with 16 CPUs on a high performance computer in a climate–only model setup. CLIMBER-X is therefore well suited to investigate the feedbacks between climate and the carbon cycle on temporal scales ranging from decades to 〉100,000 years.
    Type: Article , PeerReviewed
    Format: text
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 8
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    Silicon Isotopes in an EMIC's Ocean: Sensitivity to Runoff, Iron Supply, and Climate (2020)
    AGU (American Geophysical Union)
    Details
    Publication Date: 2023-03-09
    Description: The isotopic composition of Si in biogenic silica (BSi), such as opal buried in the oceans' sediments, has changed over time. Paleorecords suggest that the isotopic composition, described in terms of δ30Si, was generally much lower during glacial times than today. There is consensus that this variability is attributable to differing environmental conditions at the respective time of BSi production and sedimentation. The detailed links between environmental conditions and the isotopic composition of BSi in the sediments remain, however, poorly constrained. In this study, we explore the effects of a suite of offset boundary conditions during the Last Glacial Maximum (LGM) on the isotopic composition of BSi archived in sediments in an Earth System Model of intermediate complexity (EMIC). Our model results suggest that a change in the isotopic composition of Si supply to the glacial ocean is sufficient to explain the observed overall low(er) glacial δ30Si in BSi. All other processes explored trigger model responses of either wrong sign or magnitude or are inconsistent with a recent estimate of bottom water oxygenation in the Atlantic Sector of the Southern Ocean. Caveats, mainly associated with generic uncertainties in today's pelagic biogeochemical modules, remain.
    Type: Article , PeerReviewed
    Format: text
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 9
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    Constraining glacial ocean carbon cycle – A multi-model study (2024)
    In:  EPIC3
    Details
    Publication Date: 2024-04-29
    Repository Name: EPIC Alfred Wegener Institut
    Type: Conference , NonPeerReviewed
    Format: application/pdf
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    PAPER (OA)
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