Modeling in Earth system science up to and beyond IPCC AR5

Hajima, Tomohiro; Kawamiya, Michio; Watanabe, Michio; Kato, Etsushi; Tachiiri, Kaoru; Sugiyama, Masahiro; Watanabe, Shingo; Okajima, Hideki; Ito, Akinori

doi:10.1186/s40645-014-0029-y

Cited by 34 publications

(25 citation statements)

References 206 publications

(247 reference statements)

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“…Earth system models (ESMs) are recognized as the current state-of-the-art global coupled models used for climate research (e.g., Hajima et al, 2014;IPCC, 2013). They expand the numerical representation of the climate system used during the 4th IPCC assessment report (AR4) that was limited to coupled physical general circulation models, to the inclusion of biogeochemical and biophysical interactions between the physical climate system and the biosphere.…”

Section: Contextmentioning

confidence: 99%

Inconsistent strategies to spin up models in CMIP5: implications for ocean biogeochemical model performance assessment

et al. 2016

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Abstract. During the fifth phase of the Coupled Model Intercomparison Project (CMIP5) substantial efforts were made to systematically assess the skill of Earth system models. One goal was to check how realistically representative marine biogeochemical tracer distributions could be reproduced by models. In routine assessments model historical hindcasts were compared with available modern biogeochemical observations. However, these assessments considered neither how close modeled biogeochemical reservoirs were to equilibrium nor the sensitivity of model performance to initial conditions or to the spin-up protocols. Here, we explore how the large diversity in spin-up protocols used for marine biogeochemistry in CMIP5 Earth system models (ESMs) contributes to model-to-model differences in the simulated fields. We take advantage of a 500-year spin-up simulation of IPSL-CM5A-LR to quantify the influence of the spin-up protocol on model ability to reproduce relevant data fields. Amplification of biases in selected biogeochemical fields (O 2 , NO 3 , Alk-DIC) is assessed as a function of spin-up duration. We demonstrate that a relationship between spin-up duration and assessment metrics emerges from our model results and holds when confronted with a larger ensemble of CMIP5 models. This shows that drift has implications for performance assessment in addition to possibly aliasing estimates of climate change impact. Our study suggests that differences in spin-up protocols could explain a substantial part of model disparities, constituting a source of modelto-model uncertainty. This requires more attention in future Published by Copernicus Publications on behalf of the European Geosciences Union. R. Séférian et al.: Inconsistent strategies to spin up models in CMIP5model intercomparison exercises in order to provide quantitatively more correct ESM results on marine biogeochemistry and carbon cycle feedbacks.

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Section: Contextmentioning

confidence: 99%

Inconsistent strategies to spin up models in CMIP5: implications for ocean biogeochemical model performance assessment

et al. 2016

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“…1,2 Recently, global three-dimensional (3D) atmospheric transport model studies have emphasized the large uncertainties in the spatial distribution of soluble iron deposition due to combustionderived aerosols. 3−6 Iron-containing aerosols that are influenced by air masses from anthropogenic sources are often observed to have high iron solubilities (soluble Fe/total Fe).…”

Section: ■ Introductionmentioning

confidence: 99%

Atmospheric Processing of Combustion Aerosols as a Source of Bioavailable Iron

Ito

2015

Environ. Sci. Technol. Lett.

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Atmospheric processing of combustion aerosols may promote transformation of insoluble iron into soluble forms. Here, an explicit scheme for iron dissolution of combustion aerosols due to photochemical reactions with inorganic and organic acids in solution is implemented in an atmospheric chemistry transport model to estimate the atmospheric sources of bioavailable iron. The model results suggest that deposition of soluble iron from combustion sources contributes more than 40% of the total soluble iron deposition over significant portions of the open ocean in the Southern Hemisphere. A sensitivity simulation using half the iron dissolution rate for combustion aerosols results in relatively small decreases in soluble iron deposition in the ocean, compared with the large uncertainties associated with iron solubility at emission. More accurate quantification of the soluble iron burdens near the source regions and the open ocean is needed to improve the process-based understanding of the chemical modification of iron-containing minerals.

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“…Consequently, atmospheric deposition of bioavailable Fe from arid and semiarid regions might modulate primary marine productivity and thus oceanic carbon uptake in these regions during summer [Boyd et al, 2010;Conway et al, 2015;Winton et al, 2016]. However, significant uncertainties remain regarding the magnitude of the dust emissions and thus the effect of dust deposition on the oceans, especially in the Southern Hemisphere (SH) [Shao et al, 2011;Schulz et al, 2012;Hajima et al, 2014]. The major source regions of atmospheric Fe to the Southern Ocean include southern South America (Patagonia), Australia, and southern Africa [Mahowald, 2007;Li et al, 2008;Johnson et al, 2010;Ito and Shi, 2016].…”

Section: Introductionmentioning

confidence: 99%

Do dust emissions from sparsely vegetated regions dominate atmospheric iron supply to the Southern Ocean?

Ito

Kok

2017

JGR Atmospheres

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Atmospheric deposition of dust aerosols is a significant source of exogenous iron (Fe) in marine ecosystems and is critical in setting primary marine productivity during summer. This dust‐borne input of Fe is particularly important to the Southern Ocean, which is arguably the most biogeochemically important ocean because of its large spatial extent and its considerable influence on the global carbon cycle. However, there is large uncertainty in estimates of dust emissions in the Southern Hemisphere and thus of the deposition of Fe‐containing aerosols onto oceans. Here we hypothesize that sparsely vegetated surfaces in arid and semiarid regions are important sources of Fe‐containing aerosols to the Southern Ocean. We test this hypothesis using an improved dust emission scheme in conjunction with satellite products of vegetation cover and soil moisture in an atmospheric chemistry transport model. Our improved model shows a twofold increase of Fe input into the Southern Ocean in austral summer with respect to spring and estimates that the Fe input is more than double that simulated using a conventional dust emission scheme in summer. Our model results suggest that dust emissions from open shrublands contribute over 90% of total Fe deposition into the Southern Ocean. These findings have important implications for the projection of the Southern Ocean's carbon uptake.

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Modeling in Earth system science up to and beyond IPCC AR5

Cited by 34 publications

References 206 publications

Inconsistent strategies to spin up models in CMIP5: implications for ocean biogeochemical model performance assessment

Inconsistent strategies to spin up models in CMIP5: implications for ocean biogeochemical model performance assessment

Atmospheric Processing of Combustion Aerosols as a Source of Bioavailable Iron

Do dust emissions from sparsely vegetated regions dominate atmospheric iron supply to the Southern Ocean?

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