Abstract
AbstractBiological productivity in the Southern Ocean is limited by iron availability. Previous studies of iron supply have focused on mixed‐layer entrainment and diapycnal fluxes. However, the Southern Ocean is a region highly energetic mesoscale and submesoscale turbulence. Here we investigate the role of eddies in supplying iron to the euphotic zone, using a flat‐bottom zonally re‐entrant model, configured to represent the Antarctic Circumpolar Current region, that is coupled to a biogeochemical model with a realistic seasonal cycle. Eddies are admitted or suppressed by changing the model's horizontal resolution. We utilize cross spectral analysis and the generalized Omega equation to temporally and spatially decompose the vertical transport attributable to mesoscale and submesoscale motions. Our results suggest that the mesoscale vertical fluxes provide a first‐order pathway for transporting iron across the mixing‐layer base, where diapycnal mixing is weak, and must be included in modeling the open‐Southern Ocean iron budget.
Highlights
Ocean turbulence on scales of roughly 1–200 km is characterized by vigorous eddies, fronts, filaments, and other structures, which collectively make an important contribution to material transport
We argue that it is the mixing layer (MXL) and not mixed layer (ML) that is relevant for tracer subduction/obduction as MXL is the layer over which tracers are actively mixed (Balwada et al, 2018)
The MXL becomes shallower as resolution increases, which is expected as mixed-layer instability parametrization (MLI) is better resolved with increased resolution and effectively restratifies the MXL
Summary
Ocean turbulence on scales of roughly 1–200 km is characterized by vigorous eddies, fronts, filaments, and other structures, which collectively make an important contribution to material transport. In the Southern Ocean, the westerlies tend to steepen the isopycnals via Ekman pumping and make the water column more baroclinically unstable. This results in generation of mesoscale eddies, which counteract this wind-driven circulation by flattening the isopycnals. This balance plays a key role in the climate sensitivity of the global overturning circulation (Farneti et al, 2010; Zika et al, 2013; Gent, 2016; Sinha and Abernathey, 2016). Lévy et al (2010) showed that resolving the submesoscales
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
