Oceanic controls on the primary production of the northwest European continental shelf: model experiments under recent past conditions and a potential future scenario

Holt, J. ORCID: https://orcid.org/0000-0002-3298-8477; Butenschön, M.; Wakelin, S.L. ORCID: https://orcid.org/0000-0002-2081-2693; Artioli, Y.; Allen, J.I.. 2012 Oceanic controls on the primary production of the northwest European continental shelf: model experiments under recent past conditions and a potential future scenario. Biogeosciences, 9 (1). 97-117. https://doi.org/10.5194/bg-9-97-2012

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Abstract/Summary

In this paper we clearly demonstrate that changes in oceanic nutrients are a first order factor in determining changes in the primary production of the northwest European continental shelf on time scales of 5–10 yr. We present a series of coupled hydrodynamic ecosystem modelling imulations, using the POLCOMS-ERSEM system. These are forced by both reanalysis data and a single example of a coupled ocean-atmosphere general circulation model (OAGCM) representative of possible conditions in 2080–2100 under an SRES A1B emissions scenario, along with the corresponding present day control. The OA-GCM forced simulations show a substantial reduction in surface nutrients in the open-ocean regions of the model domain, comparing future and present day time-slices. This arises from a large increase in oceanic stratification. Tracer transport experiments identify a substantial fraction of on-shelf water originates from the open-ocean region to the south of the domain, where this increase is largest, and indeed the on-shelf nutrient and primary production are reduced as this water is transported on-shelf. This relationship is confirmed quantitatively by comparing changes in winter nitrate with total annual nitrate uptake. The reduction in primary production by the reduced nutrient transport is mitigated by on-shelf processes relating to temperature, stratification (length of growing season) and recycling Regions less exposed to ocean-shelf exchange in this model (Celtic Sea, Irish Sea, English Channel, and Southern North Sea) show a modest increase in primary production (of 5–10 %) compared with a decrease of 0–20% in the outer shelf, Central and Northern North Sea. These findings are backed up by a boundary condition perturbation experiment and a simple mixing model.

Item Type:	Publication - Article
Digital Object Identifier (DOI):	https://doi.org/10.5194/bg-9-97-2012
Programmes:	POL Programmes > Modelling and observation systems for shelf seas
ISSN:	1726-4189
NORA Subject Terms:	Marine Sciences
Date made live:	13 Apr 2012 14:04 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/17697

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