Oceanography seminars

Christopher R. German examines how hydrothermal circulation affects basin-scale ocean biogeochemical cycles. Early global surveys preceded the discovery of seafloor vents, and hydrothermal inputs were long considered minor and local. GEOTRACES sections and subsequent process studies have transformed that view; the presentation traces how those observations changed understanding of trace-element and isotope cycling. Laura Moore discusses the biogeochemical consequences of widespread low-temperature hydrothermal flow, highlighting advances in detection and the distinctive effects of these systems on the water column. Lise Artigue moderates this sixth seminar of the 2026 GEOTRACES online series. Attend online via the GEOTRACES recurring public Zoom meeting. The seminar begins at 15:00 CET.

NOAA’s Uncrewed Systems Operations Center operates aircraft and marine vehicles that support environmental science, operational services and stewardship. Dexter Malley and John R. Walker describe key platforms and current projects, explaining how these systems provide new approaches to collecting observations. The seminar considers how emerging technologies are being incorporated into NOAA’s applied research and operational work, with examples from marine and aviation programmes. Online via GoTo Webinar; advance registration is required. The event will be recorded. Attendees must not share personal or business-identifying information; automated AI note-taking applications are not permitted.

Satellite sea-ice concentration retrievals are commonly assimilated using a constant observational uncertainty of 0.10–0.15. This research instead estimates uncertainty within the assimilation system through an iterated Desroziers diagnostic constrained to the physical 0–1 concentration range. Two passive-microwave products and one optical product in both hemispheres show strongly state-dependent errors: roughly 0.02–0.10 near open water or complete cover, and 0.20–0.35 around half cover. Complete cover during melt remains difficult to constrain because the model rarely reproduces it. Comparisons among three collocated satellite products and published retrieval uncertainties support the pattern. The results suggest constant uncertainty overweights intermediate retrievals and underweights values near zero and one, with thin and ponded ice contributing errors beyond instrument noise.

Extreme heat affects rural communities, coastal regions and marine environments in different ways. This webinar presents NOAA-supported research that helps decision-makers target resilience measures to local conditions. Case studies address rural Vermont, Charleston and the Northeast Pacific. The speakers examine rural heat risk in relation to exposure and transportation infrastructure; resilience strategies that connect heat with flooding, water management and sea-level rise; and the drivers and subsurface characteristics of marine heatwaves in ecologically and economically important regions. The discussion connects research with practical decisions about location-specific resilience. The event forms part of NOAA’s Climate Program Office Heat Research Webinar Series, supported by NIHHIS and the Climate Variability and Predictability programme. Online via Vimeo with advance attendee registration. Live captions are available and the webinar will be recorded.

Distinguishing diatom and dinoflagellate blooms in Chesapeake Bay is difficult because its waters are optically complex and field observations rarely coincide with satellite measurements. This project combines historical phytoplankton observations, NOAA satellite bloom products, geospatial processing and ecological information in a reproducible workflow. Quality control addresses mixed pixels, land contamination, cloud, missing observations, saturation and inconsistent coordinates. Of 31,531 field-to-satellite records, 860 initially pass validation; neighbouring pixels offer further recoverable data. A preliminary Mini U-Net illustrates segmentation feasibility but exposes weak automatic labels, motivating interactive expert validation and masking. Seasonal phenology and environmental variables are evaluated as features for future multimodal models. The NOAA NERTO project was mentored by Michelle Tomlinson and Sachidananda Mishra at NCCOS.

NOAA's Mussel Watch records are examined as a unified framework for coastal contamination. The study combines sediment chemistry, toxicity, benthic condition and tissue measurements, using AMBI and M-AMBI scores at 732 national assessment sites and 33 Hudson–Raritan stations. Random-forest and Bayesian models associate urbanization with benthic condition in the New York region (ρ=0.62), but not nationally (ρ=0.05). A Delft3D estuary model reproduces observed tides and predicts increased deep-channel bed shear under sea-level rise. The work asks whether sediment contaminants mediate urbanization impacts and whether legacy cleanup remains effective as sea level changes. It was conducted through a NOAA NERTO graduate internship with Kimani Kimbrough and Erik Davenport at NCCOS.

Reducing greenhouse-gas emissions alone does not remove the excess carbon dioxide already present in the atmosphere. This talk surveys marine carbon dioxide removal approaches that use the ocean’s capacity to absorb CO₂ and explains instrumentation for evaluating their effectiveness. David Snyder describes DeepGreen Solutions’ Carbon Ocean-Based Atmospheric Linked Telemetry (COBALT) measurement system, which combines sensors on Sofar Ocean Spotter buoys and Spotter Scout autonomous surface vessels to investigate carbon-cycle processes and the atmospheric removal achieved by marine projects. The session includes questions and discussion.

This webinar examines reconstruction and use of marine metagenome-assembled genomes. The first part introduces the Ocean Microbiomics Database as a standardized resource for prokaryotic genome-resolved analysis, including co-abundance-based reconstruction, contextual metadata, and relationships between ecological patterns and microbial genomes. The second part considers why eukaryotic genomes are harder to recover: their complexity, low abundance, and limited markers and reference sequences complicate assembly and classification. Participants will compare reconstruction approaches, explore the database, and consider tools and steps for recovering eukaryotic genomes. The session serves academic and industrial researchers developing marine-microbiome applications and infrastructure teams managing samples, data, and discovery resources.

Abyssal marine turbidites provide some of the longest and most spatially extensive records of subduction zone earthquake recurrence globally; however, correlation of these deposits over long distances and interpretation of synchronous emplacement requires both an understanding of the turbidite generating systems and precise dating. Here, we present an integrated suite of high-resolution bathymetry, subbottom profiles, and sediment cores from combined autonomous underwater vehicle, remotely operated vehicle, and ship-based studies at a key paleoseismic site in the southern Cascadia subduction zone. We demonstrate how widespread, earthquake-triggered landslides on the lower slope deposit discrete, proximal mass transport deposits (MTDs) that grade offshore into complex, interfingered abyssal turbidites, which correspond to records of megathrust earthquake history. We propose accretion and oversteepening of thrust folds on the lower slope both preconditions the slope to fail and provides a perpetual source of unstable material to fail during every earthquake cycle. Furthermore, we suggest the periodic and pervasive landsliding indicates coseismic deformation of the outer accretionary wedge during megathrust rupture.

Volcanic edifice flank collapses are low-frequency, high-magnitude events that can rapidly mobilize tens of km3 of material and transport it large distances (>10 km) from the edifice. In ocean basins, these failures induce secondary hazards through the generation of tsunamis that can impact both neighboring and distal coastlines. These high-risk, far-reaching events have historically generated significant damage and loss of life, such as the 1792 collapse of the Mayuyama dome (Japan) that led to ~15,000 fatalities, and recently the 2018 collapse of Anak Krakatau (Indonesia) that resulted in ~440 deaths. Globally, there are 400–800 oceanic and coastal volcanic edifices with the potential for future collapses and associated tsunamis. Although previous studies have evaluated edifice collapse potential at both single volcanoes and over entire arcs, a global assessment of the edifices that are most capable of producing a tsunami-generating collapse is incomplete, in part because of remote locations and lack of detailed investigations. Building on previous studies, we develop a multi-component weighting procedure to rank the potential for edifice flank collapse and tsunami generation using three criteria: 1) edifice morphology; 2) satellite-derived estimations on the extent of hydrothermal alteration; and 3) 3D slope-stability analysis of potential collapses. We test this approach on oceanic and coastal volcanic edifices from the Marianas, Aleutians, Indonesia, and Philippines. After describing the results and relative ranking of edifices with the highest potential for collapse, we discuss implications for future tsunami hazard assessment.

Tom Crawford explores how mathematical models turn questions about the world into equations that can be investigated. Examples range from relativity and infectious-disease modelling to his research on the spread of pollution in the ocean. The lecture also applies modelling to video games, sport and partner selection, illustrating how the same mathematical tools can clarify problems across very different settings.

I shall present two recent piece of work investigating how shape effects the transport of active particles in shear. Firstly we will consider the sedimentation of particles in 2D laminar flow fields of increasing complexity; and how insights from this can help explain why turbulence can enhance the sedimentation of negatively buoyant diatoms [1]. Secondly, we will consider the 3D transport of elongated active particles under the action of an aligning force (e.g. gyrotactic swimmers) in some simple flow fields; and will see how shape can influence the vertical distribution, for example changing the structure of thin layers [2]. [1] Enhanced sedimentation of elongated plankton in simple flows (2018). IMA Journal of Applied Mathematics W Clifton, RN Bearon, & MA Bees. [2] Elongation enhances migration through hydrodynamic shear (in Prep), RN Bearon & WM Durham.