Biogeochemical impacts of changes in upper-ocean physics with a warming climate: reductions in nutrient supply and new production in the northeastern North Atlantic quantitatively linked to physical changes on scales down to the submesoscale

Abstract:

Using a high-resolution regional model of the Porcupine Abyssal Plain region of the North Atlantic nested into a mesoscale-resolving global ocean model, we examine how a climate perturbation based on 21st-century projections impacts vertical nutrient fluxes and new production in an idealized biogeochemical model. This idealized model allows the separation of reduced new production into the effects of the global physical model, of the interior changes in physics, and of the nutrient and light availability. From the global model, changes in circulation reduce the lateral supply of nutrients to the higher-resolution domain. The high-resolution model shows reduced winter mixed layers and increased horizontal buoyancy gradients in a warmer climate, resulting in lower submesoscale activity and reduced vertical exchange rates. Finally, the impacts of both lateral and vertical nutrient fluxes on nutrient availability and thus new production are quantified throughout the seasonal cycle.