METEC 2.0 – Offshore Emissions & the Marine Boundary Layer

Understanding methane behavior offshore is still a major scientific gap. Compared with land, there are far fewer observations of marine boundary-layer (MBL) structure and its rapid transitions—sea-breeze recirculation, nocturnal jets, and evening stabilization, among others. These regime shifts strongly influence plume transport and dilution, which in turn affect how accurately emissions can be detected and quantified. Limited empirical data offshore also makes it harder to evaluate and tune models that many decision-makers rely on.

smoke along coast of northeast England
Smoke from a near-shore chimney off the coast of NE England. The plume did not disperse vertically as it was entrained in the boundary layer moving out to sea.

This effort addresses that gap by observing key MBL behaviors at a coastal–offshore site and comparing them with widely used reanalysis products. We are focusing on how often regimes occur, how quickly they change, and how well reanalyses capture the timing and intensity of those changes. The aim is not to “pick winners,” but to map when and why model representations differ from local reality in ways that matter for methane.

Image of offshore oil rig and schematic of methane measurements near rig
Methane concentration measurements around the Breagh platform 100 km east of Teesside, NE England.

Our goals are threefold:

  1. Characterize offshore MBL regimes and translate them into practical dispersion features (e.g., expected footprint length/width, recirculation likelihood);
  2. Assess reanalysis performance for wind and mixing parameters during those regimes, with attention to transition timing;
  3. Develop simple, regime-aware guidance that helps users make better choices about when and how to sample, interpret, and model offshore emissions.

The work is designed to remain method-agnostic and compatible with a range of observation and modeling tools.

Anticipated outcomes will support multiple communities. For operators, we expect actionable guidance on “strong” and “weak” windows for leak localization, downwind sampling, and mobile surveys, plus clarity on when reanalysis-driven workflows are most defensible. For regulators, we aim to provide transparent, regime-conditioned uncertainty framing, QA/QC checklists for test conditions, and consistent ways to compare evidence across platforms. For policymakers, the results can inform inventory design and verification strategies by identifying conditions where measurements most effectively constrain coastal and regional carbon budgets.

Where feasible, we intend to release curated examples, documentation, and training materials that illustrate how regime-aware thinking can reduce uncertainty and improve comparability across studies. The content will be general by design so it can evolve as new observations and analyses come online.


Contact

Interested in collaborating, providing feedback, accessing example materials, or discussing applications? Please contact Kira Shonkwiler.