Enhanced biogeochemical cycling along the U.S. West Coast shelf
Abstract
Continental margins play an essential role in global ocean
biogeochemistry and the carbon cycle; however, global assessments of
this role remain highly uncertain. This uncertainty arises from large
variability over a broad range of temporal and spatial scales of the
processes that characterize these environments. High-resolution
simulations with ocean biogeochemical models have emerged as essential
tools to advance biogeochemical assessments at regional scales. Here, we
examine the processes and balances for carbon, oxygen, and nitrogen
cycles along the U.S. West Coast in an 11-year hindcast simulation with
a submesoscale-permitting oceanic circulation-biogeochemical model. We
highlight the importance of biogeochemical cycles on the continental
shelf, and their connection to the broader regional context encompassing
the California Current System. On the shelf, coastal and wind stress
curl upwelling drive a vigorous overturning circulation that supports
biogeochemical rates and fluxes that are approximately twice as large as
offshore. Exchanges with the proximate sediments, submesoscale shelf
currents, bottom boundary layer transport, and intensified cross-shelf
export of shelf-produced materials impact coastal and open-ocean
balances. While regional variability prevents extrapolation of our
results to global margins, our approach provides a powerful tool to
identify the dominant dynamics in different shelf setting and quantify
their large-scale consequences.