The Contribution of Surface and Submesoscale Processes to Turbulence in the Open Ocean Surface Boundary Layer

• Published in: Journal of advances in modeling earth systems 2019-12, Vol.11 (12), p.4066-4094
• Main Authors: Buckingham, Christian E., Lucas, Natasha S., Belcher, Stephen E., Rippeth, Tom P., Grant, Alan L. M., Le Sommer, Julien, Ajayi, Adekunle Opeoluwa, Naveira Garabato, Alberto C.
• Format: Article
• Language: English
• Subjects: Acoustics; Boundary layers; Deep sea moorings; dissipation; Earth; Energy dissipation; Gases; Kinetic energy; Marine environment; mixing; Momentum; Ocean circulation; Ocean models; Ocean, Atmosphere; Oceanic turbulence; Oceans; Parameterization; Salinity; Satellites; Sciences of the Universe; Studies; submesoscale; surface; Surface boundary layer; Symmetric instability; Turbulence; Turbulent kinetic energy; Winds
• ISSN: 1942-2466; 1942-2466
• DOI: 10.1029/2019MS001801

The ocean surface boundary layer is a critical interface across which momentum, heat, and trace gases are exchanged between the oceans and atmosphere. Surface processes (winds, waves, and buoyancy forcing) are known to contribute significantly to fluxes within this layer. Recently, studies have suggested that submesoscale processes, which occur at small scales (0.1–10 km, hours to days) and therefore are not yet represented in most ocean models, may play critical roles in these turbulent exchanges. While observational support for such phenomena has been demonstrated in the vicinity of strong current systems and littoral regions, relatively few observations exist in the open‐ocean environment to warrant representation in Earth system models. We use novel observations and simulations to quantify the contributions of surface and submesoscale processes to turbulent kinetic energy (TKE) dissipation in the open‐ocean surface boundary layer. Our observations are derived from moorings in the North Atlantic, December 2012 to April 2013, and are complemented by atmospheric reanalysis. We develop a conceptual framework for dissipation rates due to surface and submesoscale processes. Using this framework and comparing with observed dissipation rates, we find that surface processes dominate TKE dissipation. A parameterization for symmetric instability is consistent with this result. We next employ simulations from an ocean front‐resolving model to reestablish that dissipation due to surface processes exceeds that of submesoscale processes by 1–2 orders of magnitude. Together, these results suggest submesoscale processes do not dramatically modify vertical TKE budgets, though such dynamics may be climatically important owing to their ability to remove energy from the ocean. Key Points We present a multimonth record of OSBL turbulence in the open ocean The contribution of surface and submesoscale processes is examined Dissipation rates due to surface processes dominate those of submesoscale processes