Carbon export fluxes in the Southern Ocean: results from inverse modeling and comparison with satellite-based estimates

Schlitzer, Reiner

doi:10.1016/s0967-0645(02)00004-8

Cited by 305 publications

(305 citation statements)

References 45 publications

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“…7a). The range in data-based estimates using satellite products and inverse modeling is roughly 9 to 13 Pg-C yr −1 Laws et al, 2000;Schlitzer, 2002) with possibly significant uncertainties (Najjar et al, 2007). In our model, export production is sensitive to POC sinking rate within the parameter space, and it indicates that our sinking rate should be in the lower range to be consistent with data-based estimates.…”

Section: Biogeochemistry Model Calibrationsupporting

confidence: 63%

First description of the Minnesota Earth System Model for Ocean biogeochemistry (MESMO 1.0)

et al. 2008

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Abstract.Here we describe the first version of the Minnesota Earth System Model for Ocean biogeochemistry (MESMO 1.0), an intermediate complexity model based on the Grid ENabled Integrated Earth system model (GENIE-1). As with GENIE-1, MESMO has a 3D dynamical ocean, energy-moisture balance atmosphere, dynamic and thermodynamic sea ice, and marine biogeochemistry. Main development goals of MESMO were to: (1) bring oceanic uptake of anthropogenic transient tracers within data constraints; (2) increase vertical resolution in the upper ocean to better represent near-surface biogeochemical processes; (3) calibrate the deep ocean ventilation with observed abundance of radiocarbon. We achieved all these goals through a combination of objective model optimization and subjective targeted tuning. An important new feature in MESMO that dramatically improved the uptake of CFC-11 and anthropogenic carbon is the depth dependent vertical diffusivity in the ocean, which is spatially uniform in GENIE-1. In MESMO, biological production occurs in the top two layers above the compensation depth of 100 m and is modified by additional parameters, for example, diagnosed mixed layer depth. In contrast, production in GENIE-1 occurs in a single layer with thickness of 175 m. These improvements make MESMO a wellcalibrated model of intermediate complexity suitable for investigations of the global marine carbon cycle requiring long integration time.

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Section: Biogeochemistry Model Calibrationsupporting

confidence: 63%

First description of the Minnesota Earth System Model for Ocean biogeochemistry (MESMO 1.0)

et al. 2008

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“…Simulated surface chlorophyll (CHL a ) was compared to the SeaWiFS climatology based on satellite observations from 1997 to 2003 (Carr et al 2006). Additionally, we used multiple references for data-based estimates of marine primary productivity (Behrenfeld et al 2006) as well as export of organic carbon, calcite, and silicate (e.g., Laws et al 2000;Schlitzer 2002;Heinze et al 2003;Moore et al 2004;Jin et al 2006;Dunne et al 2007).…”

Section: Assessment Methodsmentioning

confidence: 99%

Skill assessment of three earth system models with common marine biogeochemistry

et al. 2012

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We have assessed the ability of a common ocean biogeochemical model, PISCES, to match relevant modern data fields across a range of ocean circulation fields from three distinct Earth system models: IPSL-CM4-LOOP, IPSL-CM5A-LR and CNRM-CM5.1. The first of these Earth system models has contributed to the IPCC 4th assessment report, while the latter two are contributing to the ongoing IPCC 5th assessment report. These models differ with respect to their atmospheric component, ocean subgrid-scale physics and resolution. The simulated vertical distribution of biogeochemical tracers suffer from biases in ocean circulation and a poor representation of the sinking fluxes of matter. Nevertheless, differences between upper and deep ocean model skills significantly point to changes in the underlying model representations of ocean circulation. IPSL-CM5A-LR and CNRM-CM5.1 poorly represent deep-ocean circulation compared to IPSL-CM4-LOOP degrading the vertical distribution of biogeochemical tracers. However, their representations of surface wind, wind stress, mixed-layer depth and geostrophic circulations (e.g., Antarctic Circumpolar Current) have been improved compared to IPSL-CM4-LOOP. These improvements result in a better representation of large-scale structure of biogeochemical fields in the upper ocean. In particular, a deepening of 20-40 m of the summer mixed-layer depth allows to capture the 0-0.5 lgChl L -1 concentrations class of surface chlorophyll in the Southern Ocean. Further improvements in the representation of the ocean mixedlayer and deep-ocean ventilation are needed for the next generations of models development to better simulate marine biogeochemistry. In order to better constrain ocean dynamics, we suggest that biogeochemical or passive tracer modules should be used routinely for both model development and model intercomparisons.

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“…[7] The various methods used to derive remineralization ratios are applied to the model output of the AWI Adjoint Model for Oceanic Carbon Cycling (AAMOCC) [Schlitzer, 2000[Schlitzer, , 2002. It is a 3-D ocean circulation model simulating global distributions of dissolved inorganic carbon (DIC), nitrate (NO 3 ), phosphate (PO 4 ), oxygen (O 2 ), total alkalinity (TALK), and dissolved organic matter (DOM) in addition to the hydrographic parameters temperature (T) and salinity (S).…”

Section: Model Datamentioning

confidence: 99%

“…To reach equilibrium, the model is integrated for 5000 years, until there is no net gas exchange of CO 2 between ocean and atmosphere. Particle fluxes as well as production and decay of DOM are implemented following the classical RR for C org :N:P of 106:16:1, achieving a global carbon export production of 10 Gt C [Schlitzer, 2002]. Only for the O 2 :P ratio a nonclassical Redfield value of À175 [Takahashi et al, 1985] is applied.…”

Section: Model Datamentioning

confidence: 99%

Model‐based evaluation of methods to determine C:N and N:P regeneration ratios from dissolved nutrients

Schneider¹,

Karstensen²,

Oschlies³

et al. 2005

Global Biogeochemical Cycles

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[1] Four indirect methods to determine carbon and nutrient regeneration ratios in the ocean are applied to results from a physical-biogeochemical model with prescribed element ratios for organic matter (de-)composition. The aim is to test whether these methods are suitable to reproduce C org :N:P element ratios of organic matter remineralization, which in contrast to the real ocean are exactly known in the model framework. The model experiment is carried out using the classical C:N:P Redfield ratio of 106:16:1 for production and decomposition of organic material under preindustrial atmospheric pCO 2 . Two methods rely on predefined end member values, while the others do not. The first method is a simple linear regression of two parameters, neglecting mixing effects, and yields remineralization signals biased by isopycnal tracer gradients induced by contributions of different water masses. The second method is based on multiple linear regression of three parameters, includes mixing of three, but notprescribed end members. It can, in part, reproduce the prescribed remineralization ratios. However, considerable bias appears as a result of water mass mixing. The third method considers isopycnal mixing of three prescribed end member water masses by using temperature/salinity as conservative tracers on the two density surfaces s Q = 26.8 and s Q = 27.2. On the basis of a mixing triangle approach, the method is able to reproduce the regeneration rates best in the low latitudes, where the integrated signal of remineralization is high. The fourth method uses the full set of available parameters to derive mixing fractions and remineralization and is applied to the density range from s Q = 26.8 to s Q = 27.2, yielding the best reproduction of prescribed remineralization ratios. As expected, results from the last two methods are sensitive to the choice of end member concentrations. In general, best agreement between modeled and reconstructed ratios is found between 20°N and 20°S and deviations occur toward the outcrop regions, which we account to the low amount of remineralized material together with uncertainties in prescribed end member values. Our investigation shows how apparent variability of remineralization ratios can be generated through methodological shortcomings only.Citation: Schneider, B., J. Karstensen, A. Oschlies, and R. Schlitzer (2005), Model-based evaluation of methods to determine C:N and N:P regeneration ratios from dissolved nutrients, Global Biogeochem. Cycles, 19, GB2009,

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Carbon export fluxes in the Southern Ocean: results from inverse modeling and comparison with satellite-based estimates

Cited by 305 publications

References 45 publications

First description of the Minnesota Earth System Model for Ocean biogeochemistry (MESMO 1.0)

First description of the Minnesota Earth System Model for Ocean biogeochemistry (MESMO 1.0)

Skill assessment of three earth system models with common marine biogeochemistry

Model‐based evaluation of methods to determine C:N and N:P regeneration ratios from dissolved nutrients

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