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Abstract Storms deepen the mixed layer, entrain nutrients from the pycnocline, and fuel phytoplankton blooms in midlatitude oceans. However, the effects of oceanic submesoscale (0.1–10 km horizontal scale) physical heterogeneity on the physical‐biogeochemical response to a storm are not well understood. Here, we explore these effects numerically in a Biogeochemical Large Eddy Simulation (BLES), where a four‐component biogeochemical model is coupled with a physical model that resolves some submesoscales and some smaller turbulent scales (2 km to 2 m) in an idealized storm forcing scenario. Results are obtained via comparisons to BLES in smaller domains that do not resolve submesoscales and to one‐dimensional column simulations with the same biogeochemical model, initial conditions, and boundary conditions but parameterized turbulence and submesoscales. These comparisons show different behaviors during and shortly after the storm. During the storm, resolved submesoscales double the vertical nutrient flux. The vertical diffusivity is increased by a factor of 10 near the mixed layer base, and the mixing‐induced increase in potential energy is double. Resolved submesoscales also enhance horizontal nutrient and phytoplankton variance by a factor of 10. After the storm, resolved submesoscales maintain higher nutrient and phytoplankton variance within the mixed layer. However, submesoscales reduce net vertical nutrient fluxes by 50% and nearly shut off the turbulent diffusivity. Over the whole scenario, resolved submesoscales double storm‐driven biological production. Current parameterizations of submesoscales and turbulence fail to capture both the enhanced nutrient flux during the storm and the enhanced biological production.
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Biological and physical interactions at local ocean scales: Coupled systems
Physical and biogeochemical processes that influence primary production set Earth’s carbon and heat budgets. While these processes have long been the focus of research, high resolution models to investigate local phenomena have only recently been developed, and two-way coupling between oceanic physics and biology is only recently getting attention due to computational power. With these new developments, it is possible to study the mechanisms through which these processes interact at both global and regional scales to shape Earth’s climate, which is the goal of this paper. This paper introduces oceanic physical phenomena at submesoscales to global scales – like mixed layer depth and turbulent structures – and the relationship of smaller scale events with biological factors. It discusses the implications of these relationships for primary production. After an introductory explanation of turbulence, primarily in the form of eddies and fronts, and the effects of internal instability and surface forcing, this paper emphasizes the contributions of those phenomena (turbulence, internal instability, and surface forcing) to vertical velocities and the influence of vertical transport on biology. Next, it introduces biogeochemical feedbacks, concerning both large scale population dynamics and increased absorption of radiation at the submesoscale, to consider their impacts on physical dynamics and regional climates. Finally, the paper compiles equations of irradiance and variables of significance, suggesting terms that could produce meaningful responses to variations in phytoplankton populations. The paper highlights the importance of understanding physical-biogeochemical relationships and suggests directions for future research, particularly areas related to global warming or abrupt climate change.
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- Award ID(s):
- 1655221
- PAR ID:
- 10248746
- Date Published:
- Journal Name:
- Georgetown scientific research journal
- ISSN:
- 2767-6420
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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