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dc.contributor.author
Turi, Giuliana
dc.contributor.author
Lachkar, Zouhair
dc.contributor.author
Gruber, Nicolas
dc.date.accessioned
2018-11-01T17:40:22Z
dc.date.available
2017-06-11T03:32:45Z
dc.date.available
2018-11-01T17:40:22Z
dc.date.issued
2013
dc.identifier.issn
1810-6277
dc.identifier.issn
1810-6285
dc.identifier.other
10.5194/bgd-10-14043-2013
en_US
dc.identifier.uri
http://hdl.handle.net/20.500.11850/78723
dc.identifier.doi
10.3929/ethz-b-000078723
dc.description.abstract
We quantify the CO2 source/sink nature of the California Current System (CalCS) and determine the drivers and processes behind the mean and spatiotemporal variability of the partial pressure of CO2 (pCO2) in the surface ocean. To this end, we analyze eddy-resolving, climatological simulations of a coupled physical-ecosystem-biogeochemical5 ocean model on the basis of the Regional Oceanic Modeling System (ROMS). The model-simulated pCO2 agrees very well with in situ observations over the entire domain with virtually no bias, but the model overestimates pCO2 in the nearshore 100km, and underestimates the observed temporal variability. In the annual mean, the entire CalCS within 800 km of the coast and from ∼ 33◦ N to 1046 ◦ N is essentially neutral with regard to atmospheric CO2. The model simulates an integrated uptake flux of − 0.9 TgCyr −1, corresponding to a very small average flux density of −0.05 molCm−2 yr−1, with an uncertainty of the order of ± 0.20 molCm −2 yr −1.This near zero flux is a consequence of an almost complete regional compensation between the strong outgassing in the nearshore region (first 100 km), with flux densities of more than 3molCm−2 yr−1 and a weaker, but more widespread uptake flux in the offshore region with an average flux density of −0.17 molCm−2yr−1. This pattern is primarily a result of the interaction between upwelling in the nearshore that brings waters with high concentrations of dissolved inorganic carbon (DIC) to the surface, and an intense biological drawdown of this DIC, driven by the nutrients that are upwelled20 together with the DIC. The biological drawdown occurs too slowly to prevent the escape of a substantial amount of CO2 into the atmosphere, but this is compensated by the biological generation of undersaturated conditions offshore of 100 km, permitting the CalCS to take up most of the escaped CO2. Thus, the biological pump over the entire CalCS is essentially 100 % efficient, making the preformed DIC and nutrient25 concentrations of the upwelled waters a primary determinant of the overall source/sink nature of the CalCS. The comparison of the standard simulation with one for preindustrial conditions show that the CalCS is taking up anthropogenic CO2 at a rate of about −1 molCm −2yr−1, implying that the region was a small source of CO2 to the atmosphere in preindustrial times. The air–sea CO2 fluxes vary substantially in time, both on seasonal and subseasonal timescales, largely driven by variations in surface ocean pCO2. There are important differences among the subregions. Notably, the total variance of the fluxes5 in the central nearshore CalCS is roughly 4–5 times larger than elsewhere. Most of the variability in pCO2 is associated with the seasonal cycle, except in the nearshore, where sub-seasonal variations driven by mesoscale processes dominate. In the regions off shore of 100km, changes in surface temperature are the main driver, while in the nearshore region, changes in surface temperature, as well as anomalies in DIC and 10alkalinity (Alk) owing to changes in circulation, biological productivity and air–sea CO2 fluxes dominate. The dominance of eddy-driven variability in the nearshore 100km leads to a complex spatiotemporal mosaic of surface ocean pCO2 and air–sea CO2 fluxes that require a substantial observational effort to determine the source/sink nature of this region reliably.
en_US
dc.format
application/pdf
dc.language.iso
en
en_US
dc.publisher
Copernicus
en_US
dc.rights.uri
http://creativecommons.org/licenses/by/3.0/
dc.title
Spatiotemporal variability of pCO2 and airsea CO2 uxes in the California Current System
en_US
dc.type
Journal Article
dc.rights.license
Creative Commons Attribution 3.0 Unported
ethz.title.subtitle
An eddy-resolving modeling study
en_US
ethz.journal.title
Biogeosciences Discussions
ethz.journal.volume
10
en_US
ethz.journal.abbreviated
Biogeosci. discuss.
ethz.pages.start
14043
en_US
ethz.pages.end
14091
en_US
ethz.version.deposit
publishedVersion
en_US
ethz.publication.place
Göttingen
en_US
ethz.publication.status
published
en_US
ethz.leitzahl
ETH Zürich::00002 - ETH Zürich::00012 - Lehre und Forschung::00007 - Departemente::02350 - Dep. Umweltsystemwissenschaften / Dep. of Environmental Systems Science::02721 - Inst. f. Biogeochemie u. Schadstoffdyn. / Inst. Biogeochem. and Pollutant Dynamics::03731 - Gruber, Nicolas / Gruber, Nicolas
en_US
ethz.leitzahl.certified
ETH Zürich::00002 - ETH Zürich::00012 - Lehre und Forschung::00007 - Departemente::02350 - Dep. Umweltsystemwissenschaften / Dep. of Environmental Systems Science::02721 - Inst. f. Biogeochemie u. Schadstoffdyn. / Inst. Biogeochem. and Pollutant Dynamics::03731 - Gruber, Nicolas / Gruber, Nicolas
ethz.date.deposited
2017-06-11T03:33:35Z
ethz.source
ECIT
ethz.identifier.importid
imp5936518170b7526712
ethz.ecitpid
pub:123797
ethz.eth
yes
en_US
ethz.availability
Open access
en_US
ethz.rosetta.installDate
2017-07-18T09:04:20Z
ethz.rosetta.lastUpdated
2021-02-15T02:23:02Z
ethz.rosetta.versionExported
true
ethz.COinS
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