Physical Oceanography seminars

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.

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.

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.