On the relationships between primary, net community, and export production in subtropical gyres

Brix, Holger; Gruber, Nicolas; Karl, David M.; Bates, Nicholas R.

doi:10.1016/j.dsr2.2006.01.024

Cited by 81 publications

(95 citation statements)

References 58 publications

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“…A similar evolution odel results if the cluster of high NPP sidered (not shown). The model in fact oduction during and after the 1988 La t between model and data values can ed by means of linear regression on the The slope of the regression line is sigom 1 and the coefficient of determinae lack of fit is however not caused by by unexplained variance and partly by his confirms the results of Table 1 Huisman et al, 2006;Brix et al, 2006). In this have focused on the set of data provided at the en by the modelling and synthesis group because th coherent dataset based on uniform unit and meth tions for both stations.…”

Section: The Jgofs Station Batssupporting

confidence: 72%

“…7b, the equation is given in the caption). The major discrepancy with the data is due to the bias, which is mostly found during summer when our model simulates higher than observed NPP, even if most of the previous modelling studies reported underestimation during this period (Brix et al, 2006). There is however a distinct difference between the surface and the vertically-integrated NPP values: the model overestimates NPP in the euphotic zone and underestimates the surface value (not shown).…”

Section: The Jgofs Station Batscontrasting

confidence: 38%

“…=0.38 (H 0 : slope=1 can be significantly rejected). Huisman et al, 2006;Brix et al, 2006). In this section we have focused on the set of data provided at the end of JGOFS by the modelling and synthesis group because they reflect a coherent dataset based on uniform unit and method conventions for both stations.…”

Section: The Jgofs Station Aloha (Hot)mentioning

confidence: 99%

“…Notice that these ratios are independent of the choice of the NPP computation according to the DOC percentage discussed above, since modelled NCP also includes bacterial production that originate from the utilization of DOC released by phytoplankton. The estimates computed by Brix et al (2006) might instead be affected by this factor. NPP measured through C 14 bottle incubations may be higher than reported if there is extra-cellular DOC release, and therefore the e-ratio can be substantially lower.…”

Section: Implications For the Metabolic Balance Of The Global Oceanmentioning

confidence: 99%

“…Brix et al (2006) have analysed the BATS and HOT data to quantify export production in subtropical gyres. They diagnosed metabolic rates by means of the ratio of net community production (NCP) over NPP (e-or ef-ratio), the ratio of particle production over NCP (p-ratio) and the ratio of particle production over NPP (pe-ratio, see Table 1 in Brix et al, 2006, for further descriptions and values).…”

Section: Implications For the Metabolic Balance Of The Global Oceanmentioning

confidence: 99%

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Skill assessment of the PELAGOS global ocean biogeochemistry model over the period 1980–2000

Vichi

Masina

2009

Biogeosciences

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Abstract. Global Ocean Biogeochemistry General Circulation Models are useful tools to study biogeochemical processes at global and large scales under current climate and future scenario conditions. The credibility of future estimates is however dependent on the model skill in capturing the observed multi-annual variability of firstly the mean bulk biogeochemical properties, and secondly the rates at which organic matter is processed within the food web. For this double purpose, the results of a multi-annual simulation of the global ocean biogeochemical model PELAGOS have been objectively compared with multi-variate observations from the last 20 years of the 20th century, both considering bulk variables and carbon production/consumption rates. Simulated net primary production (NPP) is comparable with satellite-derived estimates at the global scale and when compared with an independent data-set of in situ observations in the equatorial Pacific. The usage of objective skill indicators allowed us to demonstrate the importance of comparing like with like when considering carbon transformation processes. NPP scores improve substantially when in situ data are compared with modeled NPP which takes into account the excretion of freshly-produced dissolved organic carbon (DOC). It is thus recommended that DOC measurements be performed during in situ NPP measurements to quantify the actual production of organic carbon in the surface ocean. The chlorophyll bias in the Southern Ocean that affects this model as well as several others is linked to the inadequate representation of the mixed layer seasonal cycle in the region. A sensitivity experiment confirms that the artificial increase of mixed layer depths towards the observed values substantially reduces the bias. Our assessment resultsCorrespondence to: M. Vichi (vichi@bo.ingv.it) qualify the model for studies of carbon transformation in the surface ocean and metabolic balances. Within the limits of the model assumption and known biases, PELAGOS indicates a net heterotrophic balance especially in the more oligotrophic regions of the Atlantic during the boreal winter period. However, at the annual time scale and over the global ocean, the model suggests that the surface ocean is close to a weakly positive autotrophic balance in accordance with recent experimental findings and geochemical considerations.

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Section: The Jgofs Station Batssupporting

confidence: 72%

Section: The Jgofs Station Batscontrasting

confidence: 38%

Section: The Jgofs Station Aloha (Hot)mentioning

confidence: 99%

Section: Implications For the Metabolic Balance Of The Global Oceanmentioning

confidence: 99%

Section: Implications For the Metabolic Balance Of The Global Oceanmentioning

confidence: 99%

See 3 more Smart Citations

Skill assessment of the PELAGOS global ocean biogeochemistry model over the period 1980–2000

Vichi

Masina

2009

Biogeosciences

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Annual net community production and the biological carbon flux in the ocean

Emerson

2014

Global Biogeochemical Cycles

190

215

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The flux of biologically produced organic matter from the surface ocean (the biological pump), over an annual cycle, is equal to the annual net community production (ANCP). Experimental determinations of ANCP at ocean time series sites using a variety of different metabolite mass balances have made it possible to evaluate the accuracy of sediment trap fluxes and satellite-determined ocean carbon export. ANCP values at the Hawaii Ocean Time-series (HOT), the Bermuda Atlantic Time-series Study (BATS), Ocean Station Papa (OSP) are 3 ± 1 mol C m À2 yr À1 -much less variable than presently suggested by satellite remote sensing measurements and global circulation models. ANCP determined from mass balances at these locations are 3-4 times particulate organic carbon fluxes measured in sediment traps. When the roles of dissolved organic carbon (DOC) flux, zooplankton migration, and depth-dependent respiration are considered these differences are reconciled at HOT and OSP but not at BATS, where measured particulate fluxes are about 3 times lower than expected. Even in the cases where sediment trap fluxes are accurate, it is not possible to "scale up" these measurements to determine ANCP without independent determinations of geographically variable DOC flux and zooplankton migration. Estimates of ANCP from satellite remote sensing using net primary production determined by the carbon-based productivity model suggests less geographic variability than its predecessor (the vertically generalized productivity model) and brings predictions at HOT and OSP closer to measurements; however, satellite-predicted ANCP at BATS is still 3 times too low.

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Decoupling of net community and export production on submesoscales in the Sargasso Sea

Estapa

Siegel

Buesseler

et al. 2015

Global Biogeochemical Cycles

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Determinations of the net community production (NCP) in the upper ocean and the particle export production (EP) should balance over long time and large spatial scales. However, recent modeling studies suggest that a horizontal decoupling of flux-regulating processes on submesoscales (≤10 km) could lead to imbalances between individual determinations of NCP and EP. Here we sampled mixed-layer biogeochemical parameters and proxies for NCP and EP during 10, high-spatial resolution (~2 km) surface transects across strong physical gradients in the Sargasso Sea. We observed strong biogeochemical and carbon flux variability in nearly all transects. Spatial coherence among measured biogeochemical parameters within transects was common but rarely did the same parameters covary consistently across transects. Spatial variability was greater in parameters associated with higher trophic levels, such as chlorophyll in >5.0 μm particles, and variability in EP exceeded that of NCP in nearly all cases. Within sampling transects, coincident EP and NCP determinations were uncorrelated. However, when averaged over each transect (30 to 40 km in length), we found NCP and EP to be significantly and positively correlated (R = 0.72, p = 0.04). Transect-averaged EP determinations were slightly smaller than similar NCP values (Type-II regression slope of 0.93, standard deviation = 0.32) but not significantly different from a 1:1 relationship. The results show the importance of appropriate sampling scales when deriving carbon flux budgets from upper ocean observations.

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On the relationships between primary, net community, and export production in subtropical gyres

Cited by 81 publications

References 58 publications

Skill assessment of the PELAGOS global ocean biogeochemistry model over the period 1980–2000

Skill assessment of the PELAGOS global ocean biogeochemistry model over the period 1980–2000

Annual net community production and the biological carbon flux in the ocean

Decoupling of net community and export production on submesoscales in the Sargasso Sea

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