FN Archimer Export Format
PT J
TI How does the phytoplankton–light feedback affect the marine N2O inventory?
BT 
AF Berthet, Sarah
   Jouanno, Julien
   Séférian, Roland
   Gehlen, Marion
   Llovel, William
AS 1:1;2:2;3:1;4:3;5:4;
FF 1:;2:;3:;4:;5:;
C1 CNRM, Université de Toulouse, Météo-France, CNRS, Toulouse, France
   LEGOS, Université de Toulouse, IRD, CNRS, CNES, UPS, Toulouse, France
   LSCE, Université Paris-Saclay, Institut Pierre Simon Laplace, Gif-Sur-Yvette, France
   LOPS, CNRS/University of Brest/IFREMER/IRD, Brest, France
C2 CNRM (METEO FRANCE), FRANCE
   UNIV TOULOUSE, FRANCE
   IPSL, FRANCE
   CNRS, FRANCE
UM LOPS
IN WOS Cotutelle UMR
   DOAJ
   copubli-france
   copubli-univ-france
IF 7.3
TC 3
UR https://archimer.ifremer.fr/doc/00836/94755/102236.pdf
   https://archimer.ifremer.fr/doc/00836/94755/102237.pdf
   https://archimer.ifremer.fr/doc/00836/94755/102238.pdf
   https://archimer.ifremer.fr/doc/00836/94755/102239.pdf
LA English
DT Article
AB The phytoplankton–light feedback (PLF) describes the interaction between phytoplankton biomass and the downwelling shortwave radiation entering the ocean. The PLF allows the simulation of differential heating across the ocean water column as a function of phytoplankton concentration. Only one third of the Earth system models contributing to the 6th phase of the Coupled Model Intercomparison Project (CMIP6) include a complete representation of the PLF. In other models, the PLF is either approximated by a prescribed climatology of chlorophyll or not represented at all. Consequences of an incomplete representation of the PLF on the modelled biogeochemical state have not yet been fully assessed and remain a source of multi-model uncertainty in future projection. Here, we evaluate within a coherent modelling framework how representations of the PLF of varying complexity impact ocean physics and ultimately marine production of nitrous oxide (N2O), a major greenhouse gas. We exploit global sensitivity simulations at 1∘ horizontal resolution over the last 2 decades (1999–2018), coupling ocean, sea ice and marine biogeochemistry. The representation of the PLF impacts ocean heat uptake and temperature of the first 300 m of the tropical ocean. Temperature anomalies due to an incomplete PLF representation drive perturbations of ocean stratification, dynamics and oxygen concentration. These perturbations translate into different projection pathways for N2O production depending on the choice of the PLF representation. The oxygen concentration in the North Pacific oxygen-minimum zone is overestimated in model runs with an incomplete representation of the PLF, which results in an underestimation of local N2O production. This leads to important regional differences of sea-to-air N2O fluxes: fluxes are enhanced by up to 24 % in the South Pacific and South Atlantic subtropical gyres but reduced by up to 12 % in oxygen-minimum zones of the Northern Hemisphere. Our results, based on a global ocean–biogeochemical model at CMIP6 state-of-the-art level, shed light on current uncertainties in modelled marine nitrous oxide budgets in climate models. 
PY 2023
PD APR
SO Earth System Dynamics
SN 2190-4979
PU Copernicus GmbH
VL 14
IS 2
UT 000969254500001
BP 399
EP 412
DI 10.5194/esd-14-399-2023
ID 94755
ER

EF