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Eine Open-Source-Software zur Verarbeitung und Visualisierung von Seitensichtsonardaten
No full textSeitensichtsonare sind ein zentrales Werkzeug zur maritimen Kartierung, Objektidenti-
fikation und Wrackinspektion. Mit SidescanTools steht jetzt eine frei verfügbare Open-
Source-Software für die Verarbeitung gängiger Formate (XTF, JSF) bereit. Die Pythonbasierte
Anwendung bietet Funktionen wie Grundlinienerkennung, geometrische
und radiometrische Korrekturen sowie Verstärkungs-Normalisierung und verbessert
damit Auflösung und Reichweite der Daten. Ergebnisse können als georeferenzierte
Rasterbilder exportiert werden. Entwickelt im Projekt GhostNetBusters, richtet sich
SidescanTools insbesondere an Forschung, NGOs und Citizen-Science-Initiativen, die
Sonardaten kostengünstig und flexibel aufbereiten möchten
Fault-induced hydration and serpentinization of the incoming lithosphere enhances intra-slab seismicity offshore Taltal (~25{degree sign}S), Northern Chile
No full textThe northern Chilean margin is one of the most seismically active subduction zones, with a high potential for future megathrust earthquakes. The tectonic structure and the state of hydration of the incoming Nazca Plate, and their control on seismogenesis are poorly known, as the offshore domain remains largely unexplored. Here, we present high-resolution bathymetry and amphibious seismic refraction data to investigate the structure of the incoming Nazca Plate within the Taltal region (24°S–26°S). The incoming plate is characterized by E-W, trench-perpendicular oriented horst and graben structures cross-cut by N-S oriented, bending-related normal faults. The E-W orientation of the horst and graben structures is unique in northern Chile, unrelated to subduction, and we suggest they formed through N-S extension within the last 10 Ma years. This fault network facilitates seawater penetration into the crust and upper mantle, leading to widespread hydration and serpentinization. Modeling the P- and S-wave velocities and deriving the VP/VS ratio shows reduced seismic upper mantle velocities (VP ∼ 7.5 km/s; VS ∼ 3.8 km/s) and elevated VP/VS ratios (VP/VS > 1.9), suggesting up to 30% serpentinization within the upper oceanic mantle. Furthermore, we link the subsequent dehydration of the serpentinized mantle at 70–100 km depth to a pronounced cluster of intermediate-depth, intra-slab seismicity beneath the Taltal region. Our findings demonstrate that pre-existing tectonic fabrics can strongly influence the hydration budget of the incoming plate, directly impacting slab rheology and seismicity in northern Chile.
Plain Language Summary
The northern Chilean margin, where the oceanic Nazca Plate subducts beneath the continental South American Plate, is one of the most earthquake-prone subduction zones in the world. However, the offshore area near Taltal (24°S–26°S) has not been thoroughly studied, leaving gaps in understanding the controls on earthquake activity. In this study, we use detailed seafloor mapping and seismic imaging to examine the structure of the Nazca Plate as it approaches the subduction zone. We find a series of E-W oriented ridges and valleys, intersected by N-S oriented faults caused by plate bending near the subduction trench. These faults allow seawater to penetrate deep into the oceanic crust and mantle, leading to hydration and serpentinization. Seismic data reveal slower wave speeds (VP and VS) and higher VP/VS ratios close to the trench, indicating that up to 30% of the upper mantle in this region is serpentinized. As the Nazca Plate subducts, water is released at depths between 70 and 100 km, likely triggering earthquakes within the subducting slab. Our study shows that pre-existing fault patterns in the Nazca Plate strongly influence the hydration budget, affecting plate behavior during subduction and helping to explain earthquake patterns in the Taltal area.
Key Points
High-resolution bathymetry reveals trench-perpendicular horst and graben system associated with N-S extension offshore northern Chile
P- and S-wave seismic refraction tomography suggests hydration and serpentinization (up to 30%) of incoming oceanic crust and upper mantle
Seismicity observed near Taltal relates to Taltal Ridge subduction (∼20–60 km depth) and dehydration processes (∼70–100 km depth
Aquatic Productivity Signals in the Kolyma River (Northeastern Siberia) From O 2 /Ar Ratios and O 2 Triple Isotopologues
No full textArctic rivers are intricate water networks that chemically and biologically process carbon before releasing it as carbon dioxide (CO 2 ) into the atmosphere or carrying it to the ocean. Primary producers use inorganic carbon to build biomass at the base of the trophic chain. Little is known about how biogeochemical properties in Arctic rivers adapt to climate warming and changes in hydrology. To quantify net and gross biological productivity, we measured the dissolved oxygen‐to‐argon (O 2 /Ar) ratios and O 2 triple isotopologues composition in the river Kolyma and in its tributary Ambolikha during late freshet (June) and low‐flow conditions (August) in 2019. We found that hydrological factors restricted river productivity. The river system released CO 2 into the atmosphere in June and August, however August emissions were only 6% of late freshet emissions. In June, higher river flow and turbidity restricted river production, but in August, lower flows allowed more light penetration and a phytoplankton bloom at the tributary‐main Kolyma channel confluence. CO 2 emissions per area during June and August accounted for 5 ± 11% of the gross carbon uptake estimated during a bloom event. Thus, in‐stream metabolism can exceed riverine CO 2 emissions under certain flow and light conditions. Arctic climate change may promote biological productivity in particular locations along with changes in dissolved organic matter signature and microbiome, and contribute to Arctic river carbon budgets as flow slows during prolongued open water periods.
Plain Language Summary
Arctic rivers are complex systems of water that break down carbon chemically and biologically before releasing it into the air as carbon dioxide (CO 2 ) or taking it to the ocean. Tiny organisms at the base of the food chain, called primary producers, use CO 2 to create their food and build up their bodies with the support of light and nutrients. However, we do not fully understand how they adjust to climate change in the Arctic. In 2019, we measured the concentration of oxygen and argon and identified the different sources of oxygen in the water to calculate the amount of carbon that is consumed and released in the Kolyma and Ambolikha rivers in northeastern Siberia. We found that in June, after the snow and ice melt period, the river mainly releases CO 2 to the atmosphere, and there are few primary producers because the river is turbid. However, as the river flow settles down in August, more light penetrates the water column, and in some river areas, primary producers grow. Extended ice‐free periods and reduced flow in Arctic rivers favor the growth and establishment of primary producers.
Key Points
Kolyma and Ambolikha rivers are large CO 2 emitters in the late‐freshet, but CO 2 emissions decrease considerably during the low‐flow period
High river flows and turbidity restrict river productivity during late‐freshet in June
Increased light penetration and nutrients allow phytoplankton blooms in river‐stream confluences during low‐flow conditions in Augus
Advancing Climate System Understanding: Insights from the PalMod Project
No full textThe PalMod project, funded by the German Federal Ministry of Education and Research (BMBF), aims at addressing key knowledge gaps in the understanding of the dynamics and variability of the climate system during the last glacial cycle. This period, which is marked by strong and rapid climatic fluctuations, serves as a testbed for complex Earth system models (ESMs). The models tested in this way will be used in climate-change scenarios for the next millennia to enhance future climate-change assessments. PalMod uses three ESMs—AWI-ESM, MPI-ESM, and CESM— that integrate physical and biogeochemical processes and employ advanced parameterizations regarding, for example, ice sheet-ocean interactions.
In Phases I and II, the project focused on key epochs of the last glacial cycle including inception, MIS3, and the last deglaciation. The ongoing final Phase III leverages these insights to project the climate over the next millennia. Central to this last project phase is to answer some of the major societally critical questions in association with climate change: What are the potential tipping points and at which global warming may they become relevant? Under what conditions could polar ice sheets collapse catastrophically, and how rapidly could sea levels rise under different future climate scenarios? How will permafrost evolve in a warming world? This presentation reflects on the progress made during the past two phases of the project and presents preliminary answers to the aforementioned pressing questions
Supplementary model data to: Hidden vortices: Near-equatorial low-oxygen extremes driven by high-baroclinic-mode vortices.
No full textThe data are an excerpt of the CM2.6-miniBLING control simulation run at the NOAA Geophysical Fluid Dynamics Laboratory, GFDL. For more information about the climate model CM2.6-miniBLING see e.g., Griffies et al, 2015 (physical climate model) and Galbraith et al, 2015) (ocean biogeochemical module). The dataset here presents a set of physical and biogeochemical variables that have been extracted from the CM2.6 simulation for the tropical Atlantic for the last 20 years of the control simulation for the top 500 m of the water column in five daily resolution. See details in Schütte et al, 2025
The marine biological carbon pump and atmospheric carbon dioxide - idealised UVic model experiments. Part 2: transient experiments
No full textThis is a dataset which includes output and code from several idealised Earth System model experiments carried out with the UVic Earth System Model. Experiments have been carried out to to exemplify the relationship between metrics used to describe the marine biological carbon pump and atmospheric CO2. Experiments have originally been designed and carried out to support teaching of aspects of marine biogeochemical modelling at GEOMAR and CAU Kiel. Experiments published here represent transient model experiments run under RCP 8.5 CO2 emission forcing and respective control experiments with zero emissions. The transient experiment and control experiments branch off from 8000 model year long spinup experiments run under prescribed constant preindustrial pCO2.
See METHODS and docu/METHODS_Koeve_2025c.pdf for details. Computations have been carried out at the Kiel University Computing Centre (NEC cluster)
Dataset of oil slicks, look-alikes and remarkable SAR signatures obtained from Sentinel-1 data in the Eastern Mediterranean Sea
No full textPublicly available datasets for oil spill detection are scarce, making it difficult to compare the performance of different detection algorithms. To address this, this paper introduces a comprehensive labeled dataset of oil slicks, look-alikes, and other remarkable oceanic phenomena, derived from Sentinel-1 Synthetic Aperture Radar (SAR) products in the Eastern Mediterranean Sea in 2019. The dataset contains 3225 oil objects across 1365 image patches, along with an additional 2290 image patches featuring look-alikes or other phenomena. Data are available at 10.1594/PANGAEA.980773 .This dataset enables researchers to evaluate their oil spill detection models and compare performance with other studies. To facilitate this, the performance of an oil spill detector from a previous study on the dataset is provided as a baseline. In addition, to help the researchers better understand what phenomena their object detector might be confusing with oil slicks, the image patches without oil objects were sorted into several subgroups. On the other hand, for researchers looking to apply object detection models to oil slick detection but lacking a starting dataset, this dataset can serve as a valuable training resource. Beyond dataset presentation, this paper also explains the formation of different oceanic phenomena and their SAR signatures, supported by examples and supplementary materials. These insights help researchers from various backgrounds, such as remote sensing, oceanography, and machine learning, better understand the sources of SAR signatures
Natural ocean alkalinization through erosion of glacial till and weathering at the seafloor
No full textThe ocean absorbs about 25% of anthropogenic carbon dioxide emissions, with this uptake regulated by acid-neutralizing anions collectively termed alkalinity. Most seawater alkalinity originates from the weathering of aluminosilicate and carbonate minerals on land, whose dissolved products are transported to the ocean by rivers, a slow process that causes carbon dioxide removal to lag behind emissions. Here we present geochemical evidence showing that fine-grained glacial sediments mobilized by coastal erosion undergo rapid seafloor weathering. While aluminosilicate weathering is largely balanced by secondary clay formation (reverse weathering), carbonate dissolution yields a significant net release of alkalinity to coastal waters. Because more than two-thirds of the global coastline was formerly glaciated, ongoing deglaciation and erosion may enhance alkalinity fluxes, providing a previously unrecognized shortcut in the global carbon cycle. As this enhanced flux is ultimately driven by climate warming, it may act as a negative feedback that helps moderate future increases in atmospheric carbon dioxide
Research Software Lifecycles and Stages
No full textResearch software is usually developed by researchers themselves or by software developers working closely with researchers. It is typically developed to meet specific research needs. We develop and evaluate a comprehensive and flexible software lifecycle framework that reflects the unique challenges of research software. In review of related work on commercial and open-source software lifecycles, we observed limitations in addressing the heterogeneous, irregular development patterns, and longitudinal and cyclical nature of many research software projects. An initial model, which was based on case-study research of thirty-eight open-source projects was refined through collaborative discussion at a Dagstuhl seminar, introducing additional state transitions, and expanding details on blocked and active development stages for the specific context of research software. We highlight the overlap and extensions in the new model compared to prior literature and present the evaluation with the research software community. We derive the research software stages from our lifecycle model to categorise research software accordingly