How does the phytoplankton–light feedback affect the marine N2O inventory?
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Published:2023-04-12
Issue:2
Volume:14
Page:399-412
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ISSN:2190-4987
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Container-title:Earth System Dynamics
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language:en
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Short-container-title:Earth Syst. Dynam.
Author:
Berthet SarahORCID, Jouanno JulienORCID, Séférian RolandORCID, Gehlen MarionORCID, Llovel William
Abstract
Abstract. 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.
Publisher
Copernicus GmbH
Subject
General Earth and Planetary Sciences
Reference66 articles.
1. Anderson, W. G., Gnanadesikan, A., Hallberg, R., Dunne, J., and Samuels, B. L.: Impact of ocean color on the maintenance of the Pacific Cold Tongue, Geophys. Res. Lett., 34, L11609, https://doi.org/10.1029/2007GL030100, 2007. 2. Arévalo-Martínez, D. L., Kock, A., Steinhoff, T., Brandt, P., Dengler, M., Fischer, T., Körtzinger, A., and Bange, H. W.: Nitrous oxide during the onset of the Atlantic cold tongue, J. Geophys. Res.-Oceans, 122, 171–184, https://doi.org/10.1002/2016JC012238, 2017. 3. Arévalo-Martínez, D. L., Steinhoff, T., Brandt, P., Körtzinger, A., Lamont, T., Rehder, G., and Bange, H. W.: N2O emissions from the northern Benguela upwelling system, Geophys. Res. Lett., 46, 3317–3326, https://doi.org/10.1029/2018GL081648, 2019. 4. Asselot, R., Lunkeit, F., Holden, P. B., and Hense, I.: Climate pathways behind phytoplankton-induced atmospheric warming, Biogeosciences, 19, 223–239, https://doi.org/10.5194/bg-19-223-2022, 2022. 5. Aumont, O., Ethé, C., Tagliabue, A., Bopp, L., and Gehlen, M.: PISCES-v2: an ocean biogeochemical model for carbon and ecosystem studies, Geosci. Model Dev., 8, 2465–2513, https://doi.org/10.5194/gmd-8-2465-2015, 2015.
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