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GEOMAR Library Ocean Research Information Access

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  • AGU (American Geophysical Union)  (39)
  • PANGAEA  (12)
  • 2020-2024  (38)
  • 2010-2014  (13)
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  • 1
    Publication Date: 2024-06-09
    Description: The ²³⁴Th-²³⁸U radioactive pair has been extensively used to evaluate the efficiency with which photosyntetically fixed carbon is exported from the surface ocean by means of the biological pump since the 90's. The seminal work of Buesseler et al. (1992) proposed that particulate organic carbon (POC) flux can be indirectly calculated from ²³⁴Th distributions if the ratio of POC to ²³⁴Th measured on sinking particles (POC:²³⁴Th) at the desired export depth is known. Since then, a huge amount of ²³⁴Th depth profiles have been collected using a variety of sampling instruments and strategies that have changed along years. This is a global oceanic compilation of ²³⁴Th measurements, that collects results from innumerable researchers and laboratories over a period exceeding 50 years. The present compilation is made of a total 223 datasets: 214 from studies published either in articles in referred journals, PhD thesis or repositories, and 9 unpublished datasets. Including measurements from JGOFS, VERTIGO and GEOTRACES programs, with sampling from approximately 5000 locations spanning all the oceans. The compilation includes total ²³⁴Th profiles, dissolved and particulate ²³⁴Th concentrations, and POC:²³⁴Th ratios (both from pumps and sediment traps) for two sizes classes (1-53 μm and 〈 53 μm) when available. Appropriate metadata have been included, including geographic location, date, and sample depth, among others. When available, we also include water temperature, salinity, ²³⁸U data and particulate organic nitrogen data. Data sources and methods information (including ²³⁸U and ²³⁴Th) are also detailed along with valuable information for future data analysis such as bloom stage and steady/non-steady state conditions at the sampling moment. This undertaking is a treasure of data to understand and quantify how oceanic carbon cycle functions and how it will change in future. The compilation can be downloaded in three different ways: 1) A single merged file including all the individual excel files. This option can be accessed under "Other version: More than 50 years of Th-234 data: a comprehensive global oceanic compilation (single xlsx file)". 2) A summary table that includes details from cruise, sampling dates, techniques applied, authors and DOI of the compiled ²³⁴Th data, among others, each line corresponds to a specific dataset. The table can be accessed by clicking ""View dataset as HTML" and downloaded in "Download dataset as tab-delimited text". 3) Individual Excel files for each dataset can be manually chosen from the summary table, corresponding to the complete ²³⁴Th dataset and metadata from a specific publication or program. This option is available by clicking "View dataset as HTML". Furthermore, all files referred to can be downloaded in one go as ZIP or TAR.
    Keywords: 234Th; Author(s); Binary Object; biological carbon pump; Carbon, organic, particulate/Thorium-234 ratio; carbon export; Chief scientist(s); Cruise/expedition; DATE/TIME; ELEVATION; Gear; GEOTRACES; Global marine biogeochemical cycles of trace elements and their isotopes; JGOFS; Joint Global Ocean Flux Study; Journal/report title; LATITUDE; LONGITUDE; Multiple cruises/expeditions; Ocean; Ocean and sea region; Period; POC flux; Project; Reference of data; Thorium-234, dissolved; Thorium-234, particulate; Thorium-234, total; Uniform resource locator/link to reference; Uranium-238; Vessel; Year of publication
    Type: Dataset
    Format: text/tab-separated-values, 4056 data points
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  • 2
    Publication Date: 2024-04-27
    Description: There is a growing need for past weather and climate data to support science and decision-making. This paper describes the compilation and the construction of a global multivariable (air temperature, pressure, precipitation sum, number of precipitation days) monthly instrumental climate database that encompasses a substantial body of the known early instrumental time series. The dataset contains series compiled from existing databases that start before 1890 (though continuing to the present) as well as a large amount of newly rescued data. All series underwent a quality control procedure and subdaily series were processed to monthly mean values. An inventory was compiled, and the collection was deduplicated based on coordinates and mutual correlations. The data are provided in a common format accompanied by the inventory. The collection totals 12452 meteorological records in 118 countries. The data has been merged from 18250 original data files. The data can be used for climate reconstructions and analyses. It is the most comprehensive global monthly climate data set for the preindustrial period.
    Keywords: A Palaeoreanalysis To Understand Decadal Climate Variability; de-duplication; early instrumental; GlobCover; PALAEO-RA; paleoclimatology; Paleometeorology; quality control; Time series
    Type: Dataset
    Format: application/zip, 24 datasets
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  • 3
    Publication Date: 2023-02-08
    Description: Forecasting and early warning systems are important investments to protect lives, properties and livelihood. While early warning systems are frequently used to predict the magnitude, location and timing of potentially damaging events, these systems rarely provide impact estimates, such as the expected amount and distribution of physical damage, human consequences, disruption of services or financial loss. Complementing early warning systems with impact forecasts has a two‐fold advantage: it would provide decision makers with richer information to take informed decisions about emergency measures, and focus the attention of different disciplines on a common target. This would allow capitalizing on synergies between different disciplines and boosting the development of multi‐hazard early warning systems. This review discusses the state‐of‐the‐art in impact forecasting for a wide range of natural hazards. We outline the added value of impact‐based warnings compared to hazard forecasting for the emergency phase, indicate challenges and pitfalls, and synthesize the review results across hazard types most relevant for Europe. Plain language summary Forecasting and early warning systems are important investments to protect lives, properties and livelihood. While such systems are frequently used to predict the magnitude, location and timing of potentially damaging events, they rarely provide impact estimates, such as the expected physical damage, human consequences, disruption of services or financial loss. Extending hazard forecast systems to include impact estimates promises many benefits for the emergency phase, for instance, for organising evacuations. We review and compare the state‐of‐the‐art of impact forcasting across a wide range of natural hazards, and outline opportunities and key challenges for research and development of impact forecasting.
    Type: Article , PeerReviewed , info:eu-repo/semantics/article
    Format: text
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  • 4
    Publication Date: 2024-02-07
    Description: Accurately predicting future ocean acidification (OA) conditions is crucial for advancing OA research at regional and global scales, and guiding society's mitigation and adaptation efforts. This study presents a new model-data fusion product covering 10 global surface OA indicators based on 14 Earth System Models (ESMs) from the Coupled Model Intercomparison Project Phase 6 (CMIP6), along with three recent observational ocean carbon data products. The indicators include fugacity of carbon dioxide, pH on total scale, total hydrogen ion content, free hydrogen ion content, carbonate ion content, aragonite saturation state, calcite saturation state, Revelle Factor, total dissolved inorganic carbon content, and total alkalinity content. The evolution of these OA indicators is presented on a global surface ocean 1° × 1° grid as decadal averages every 10 years from preindustrial conditions (1750), through historical conditions (1850–2010), and to five future Shared Socioeconomic Pathways (2020–2100): SSP1-1.9, SSP1-2.6, SSP2-4.5, SSP3-7.0, and SSP5-8.5. These OA trajectories represent an improvement over previous OA data products with respect to data quantity, spatial and temporal coverage, diversity of the underlying data and model simulations, and the provided SSPs. The generated data product offers a state-of-the-art research and management tool for the 21st century under the combined stressors of global climate change and ocean acidification. The gridded data product is available in NetCDF at the National Oceanic and Atmospheric Administration (NOAA) National Centers for Environmental Information: https://www.ncei.noaa.gov/data/oceans/ncei/ocads/metadata/0259391.html, and global maps of these indicators are available in jpeg at: https://www.ncei.noaa.gov/access/ocean-carbon-acidification-data-system/synthesis/surface-oa-indicators.html. Key Points: - This study presents the evolution of 10 ocean acidification (OA) indicators in the global surface ocean from 1750 to 2100 - By leveraging 14 Earth System Models (ESMs) and the latest observational data, it represents a significant advancement in OA projections - This inter-model comparison effort showcases the overall agreements among different ESMs in projecting surface ocean carbon variables
    Type: Article , PeerReviewed
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  • 5
    Publication Date: 2023-02-08
    Description: Ocean deoxygenation is a threat to marine ecosystems. We evaluated the potential of two ocean intervention technologies, i.e. “artificial downwelling (AD)” and “artificial upwelling (AU)”, for remedying the expansion of Oxygen Deficient Zones (ODZs). The model‐based assessment simulated AD and AU implementations for 80 years along the eastern Pacific ODZ. When AD was simulated by pumping surface seawater to the 178 ~ 457 m depth range of the ODZ, vertically integrated oxygen increased by up to 4.5% in the deployment region. Pumping water from 457 m depth to the surface (i.e. AU), where it can equilibrate with the atmosphere, increased the vertically integrated oxygen by 1.03%. However, both simulated AD and AU increased biological production via enhanced nutrient supply to the sea surface, resulting in enhanced export production and subsequent aerobic remineralization also outside of the actual implementation region, and an ultimate net decline of global oceanic oxygen.
    Type: Article , PeerReviewed
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  • 6
    Publication Date: 2024-01-16
    Description: Data on infauna and sediment characteristics were collected as part of an extensive research program on the effects of offshore wind turbines on the marine environment funded by the German Federal Maritime and Hydrographic Agency. The investigations were performed in the first German offshore wind farm alpha ventus in the German Bight (North Sea). The overall aim of the program was to evaluate the German national standard concept for environmental impact assessments for offshore wind farms. Specifically, our study addressed the potential changes of the infauna communities in different distances from single turbines in an early stage of the operational phase of the wind farm. The data were collected during the cruises HE296 (2008), HE313 (2009), HE340 (2010) and HE369 (2000) of the German research vessel RV Heincke. Infauna samples were taken with van Veen grab samples (sampling area: 0.1 m2, weight: 95 kg) inside the wind farm and in two reference sites outside the wind farm. Three replicate samples were taken at each station. The samples were sieved through a 1 mm mesh and species of the macro-infauna were determined to the lowest taxonomic level possible. Sub-samples of the sediments were fractionated in a cascade of sieves of different mesh sizes to determine the grain size distributions. The organic contents of the sediments were determined as weight loss on ignition. The dataset comprises 11,400 count and biomass records for 103 infaunal taxa (89 % on species level, 11 % others) from 528 samples. Sediments were characterised for 176 van Veen grabs.
    Type: Dataset
    Format: application/zip, 2 datasets
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  • 7
    Publication Date: 2024-02-14
    Description: Polar marine ecosystems are particularly vulnerable to the effects of climate change. Warming temperatures, freshening seawater, and disruption to sea-ice formation potentially all have cascading effects on food webs. New approaches are needed to better understand spatiotemporal interactions among biogeochemical processes at the base of Southern Ocean food webs. In marine systems, isoscapes (models of the spatial variation in the stable isotopic composition) of carbon and nitrogen have proven useful in identifying spatial variation in a range of biogeochemical processes, such as nutrient utilization by phytoplankton. Isoscapes provide a baseline for interpreting stable isotope compositions of higher trophic level animals in movement, migration, and diet research. Here, we produce carbon and nitrogen isoscapes across the entire Southern Ocean (〉40°S) using surface particulate organic matter isotope data, collected over the past 50 years. We use Integrated Nested Laplace Approximation-based approaches to predict mean annual isoscapes and four seasonal isoscapes using a suite of environmental data as predictor variables. Clear spatial gradients in δ13C and δ15N values were predicted across the Southern Ocean, consistent with previous statistical and mechanistic views of isotopic variability in this region. We identify strong seasonal variability in both carbon and nitrogen isoscapes, with key implications for the use of static or annual average isoscape baselines in animal studies attempting to document seasonal migratory or foraging behaviors.
    Type: Article , PeerReviewed , info:eu-repo/semantics/article
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  • 8
    Publication Date: 2024-02-07
    Description: The intraplate Hawaiian-Emperor Seamount Chain has long been considered a hotspot track generated by the motion of the Pacific plate over a deep mantle plume, and an ideal feature therefore for studies of volcanic structure, magma supply, plume-crust interaction, flexural loading, and upper mantle rheology. Despite their importance as a major component of the chain, the Emperor Seamounts have been relatively little studied. In this paper, we present the results of an active-source wide-angle reflection and refraction experiment conducted along an ocean-bottom-seismograph (OBS) line oriented perpendicular to the seamount chain, crossing Jimmu guyot. The tomographic P wave velocity model, using ∼20,000 travel times from 26 OBSs, suggests that there is a high-velocity (〉6.0 km/s) intrusive core within the edifice, and the extrusive-to-intrusive ratio is estimated to be ∼2.5, indicating that Jimmu was built mainly by extrusive processes. The total volume for magmatic material above the top of the oceanic crust is ∼5.3 × 104 km3, and the related volume flux is ∼0.96 m3/s during the formation of Jimmu. Under volcanic loading, the ∼5.3-km-thick oceanic crust is depressed by ∼3.8 km over a broad region. Using the standard relationships between Vp and density, the velocity model is verified by gravity modeling, and plate flexure modeling indicates an effective elastic thickness (Te) of ∼14 km. Finally, we find no evidence for large-scale magmatic underplating beneath the pre-existing crust.
    Type: Article , PeerReviewed
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    Format: other
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  • 9
    Publication Date: 2024-05-21
    Description: Freshwater input from Greenland ice sheet melt has been increasing in the past decades from warming temperatures. To identify the impacts from enhanced meltwater input into the subpolar North Atlantic from 1997 to 2021, we use output from two nearly identical simulations in the eddy-rich model VIKING20X (1/20°) only differing in the freshwater input from Greenland: one with realistic interannually varying runoff increasing in the early 2000s and the other with climatologically (1961–2000) continued runoff. The majority of the additional freshwater remains within the boundary current enhancing the density gradient toward the warm and salty interior waters yielding increased current velocities. The accelerated boundary current shows a tendency to enhanced, upstream shifted eddy shedding into the Labrador Sea interior. Further, the experiments allow to attribute higher stratification and shallower mixed layers southwest of Greenland and deeper mixed layers in the Irminger Sea, particularly in 2015–2018, to the runoff increase in the early 2000s. Key Points The West Greenland Current (WGC) freshens and cools with the observed recent increase in meltwater runoff from Greenland The density gradient across the boundary current intensifies, strengthening the WGC and increasing local eddy formation Enhanced meltwater runoff contributed to an eastward shift in deep convection towards the Irminger Sea (2015–2018) Plain Language Summary Global warming has accelerated the melting of the Greenland ice sheet over the past few decades resulting in enhanced freshwater input into the North Atlantic. The additional freshwater can potentially inhibit deep water formation and have future implications on ocean circulation. To determine the influence from Greenland melt, we compare two high-resolution model experiments all with the same forcing but differing input of Greenland freshwater fluxes from 1997 to 2021. We find that in the experiment with realistically increasing Greenland meltwater, the water becomes fresher and cooler along the continental shelf and boundary of the subpolar gyre. The density difference between the shelf and interior increases with more freshwater, resulting in faster West Greenland Current speeds and enhanced eddy formation. Deeper mixed layers are found in the eastern Irminger Sea, particularly in 2015–2018. From 2009 to 2013, there were shallower mixed layers in the Labrador Sea where less Greenland meltwater was mixed downwards and spread eastward, causing mixed layers to deepen in the Irminger Sea.
    Type: Article , PeerReviewed , info:eu-repo/semantics/article
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  • 10
    Publication Date: 2024-02-26
    Description: Submarine landslides pose a hazard to coastal communities and critical seafloor infrastructure, occurring on all of the world's continental margins, from coastal zones to hadal trenches. Offshore monitoring has been limited by the largely unpredictable occurrence of submarine landslides and the need to cover large regions. Recent subsea monitoring has provided new insights into the preconditioning and run-out of submarine landslides using active geophysical techniques. However, these tools measure a small spatial footprint and are power- and memory-intensive, thus limiting long-duration monitoring. Most landslide events remain unrecorded. In this chapter, we first show how passive acoustic and seismologic techniques can record acoustic emissions and ground motions created by terrestrial landslides. This terrestrial-focused research has catalyzed advances in characterizing submarine landslides using onshore and offshore networks of broadband seismometers, hydrophones, and geophones. We discuss new insights into submarine landslide preconditioning, timing, location, velocity, and down-slope evolution arising from these advances. Finally, we outline challenges, emphasizing the need to calibrate seismic and acoustic signals generated by submarine landslides. Passive seismic and acoustic sensing has a strong potential to enable more complete hazard catalogs to be built and open the door to emerging techniques (such as fiber-optic sensing) to fill key knowledge gaps.
    Type: Book chapter , NonPeerReviewed
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