Abstract
In the recent past observational and modelling studies have shown that the vertical displacement of water parcels, and therefore, phytoplankton particles in regions of deep-reaching convection plays a key role in late winter/early spring primary production. The underlying mechanism describes how convection cells capture living phytoplankton cells and recurrently expose them to sunlight.This study presents a parameterisation called 'phytoconvection' which focusses on the influence of convection on primary production. This parameterisation was implemented into a three-dimensional physical-biogeochemical model and applied to the Northwestern European Continental Shelf and areas of the adjacent Northeast Atlantic. The simulation was compared to a 'conventional' parameterisation with respect to its influence on phytoplankton concentrations during the annual cycle and its effect on the carbon cycle.The simulation using the new parameterisation showed good agreement with observation data recorded during winter, whereas the reference simulation did not capture the observed phytoplankton concentrations. The new parameterisation had a strong influence on the carbon export through the sinking of particulate organic carbon. The carbon export during late winter/early spring significantly exceeded the export of the reference run.Furthermore, a non-hydrostatic convection model was used to evaluate the major assumption of the presented parameterisation which implies the matching of the mixed layer depth with the convective mixing depth. The applied mixed layer depth criterion principally overestimates the actual convective mixing depth. However, the results showed that this assumption is reasonable during late winter, while indicating a mismatch during spring.
Original language | English |
---|---|
Pages (from-to) | 138-152 |
Number of pages | 15 |
Journal | Journal of Marine Systems |
Volume | 147 |
Early online date | 11 Jul 2014 |
DOIs | |
Publication status | Published - 31 Jul 2015 |
Funding
We thank Detlef Quadfasel for kindly providing us the ARGO float pictures and the British Oceanographic Data Centre (BODC) for providing the observation profile data. Furthermore, we thank Wilfried Kühn for proofreading the article and giving helpful comments. We also thank the reviewers for the constructive criticism. Fabian Große thanks Bettina Walter for fruitful discussions. Christian Lindemann was partly financially supported by the FP7 (Grant number: EC Grant Agreement 264 933 ) programme EURO-BASIN. This study uses data from the Land Ocean Interaction Study - Shelf Edge Study (LOIS-SES), provided by the British Oceanographic Data Centre (BODC) and funded by the UK Natural Environment Research Council (NERC).
Keywords
- biogeochemical modelling
- convection
- Northeast Atlantic
- Northwestern European Continental Shelf
- parameterisation
- primary production