Ocean processes underlying surface clustering. Issue 1 (10th January 2016)

• Record Type: Journal Article
• Authors: Jacobs, Gregg A.; Huntley, Helga S.; Kirwan, A. D.; Lipphardt, Bruce L.; Campbell, Timothy; Smith, Travis; Edwards, Kacey; Bartels, Brent
• Is Part Of: Journal of geophysical research. Volume 121:Issue 1(2016:Jan.)
• Page Start: 180
• Page End: 197
• Publication Date: 2016-01-10
• Subjects: clustering -- divergence -- frontogenesis -- submesoscale -- continental shelf -- modeling; Oceanography -- Periodicals; 551.4605
• DOI: 10.1002/2015JC011140
• Languages: English
• ISSNs: 2169-9275

Abstract

Abstract: Ageostrophic ocean processes such as frontogenesis, submesoscale mixed‐layer instabilities, shelf break fronts, and topographic interactions on the continental shelf produce surface‐divergent flows that affect buoyant material over time. This study examines the ocean processes leading to clustering, i.e., the increase of material density over time, on the ocean surface. The time series of divergence along a material trajectory, the Lagrangian divergence (LD), is the flow property driving clustering. To understand the impacts of various ocean processes on LD, numerical ocean model simulations at different resolutions are analyzed. Although the relevant processes differ, patterns in clustering evolution from the deep ocean and the continental shelf bear similarities. Smaller‐scale ocean features are associated with stronger surface divergence, and the surface material clustering is initially dominated by these features. Over time, the effect of these small‐scale features becomes bounded, as material traverses small‐scale regions of both positive and negative divergence. Lower‐frequency flow phenomena, however, continue the clustering. As a result, clustering evolves from initial small‐scale to larger‐scale patterns. Key Points: Ocean processes generate surface divergence that changes surface material density Smaller‐scale processes have stronger divergence, and initially are the dominant impact Larger‐scale processes continue material density change at longer time scales