Data-Based Evaluation Of Global Carbon Cycle Models Used For Ocean Acidification Research

Koeve, Wolfgang, Barkmann, Wolfgang, Duteil, Olaf and Oschlies, Andreas (2012) Data-Based Evaluation Of Global Carbon Cycle Models Used For Ocean Acidification Research [Poster] In: "The ocean in a high CO2 World" 3. Symposium, 24.-27.09.2012, Monterey, USA.

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Ocean biogeochemical models are routinely applied to assess the net global impact of ocean acidification and warming on pelagic CaCO3 cycling. As with respect to the net change of global air-sea carbon fluxes affected by the reduced calcification under future CO2 conditions, these models diverge by a factor of four. The standard method to evaluate modeled CaCO3 cycles is to compare alkalinity and CaCO3 saturation states with observations. In general, state-of-the-art models do feature strong deviations and it is unclear if, or to what extent, these are driven by a deficient representation of physics (ocean circulation) or a deficient representation of biogeochemistry. This points to a strong need for improvement of the data-based evaluation of the base state of global biogeochemical models used for ocean acidification research.

Here we apply the TA* method to output from a variety of model experiments and observations (GLODAP). This method was originally developed to separate the signals of CaCO3 production and dissolution from the large, conservative alkalinity background in observations and is also a critical part of approaches used to quantify the inventory of anthropogenic CO2 in the ocean.

The aim is our study is twofold. First, to assess the TA* method using additional explicit representations of preformed alkalinity, accumulated CaCO3 dissolution, and organic matter remineralisation in our models. And second, we aim to disentangle deficiencies in the physical and biogeochemical CaCO3-cyle module in a series of ocean biogeochemical models of increasing complexity. Finally, our modeling study provides a critical assessment of the ‘mystery of shallow CaCO3 dissolution’, i.e. apparent dissolution of major CaCO3 minerals well above their saturation horizon.

Document Type: Conference or Workshop Item (Poster)
Keywords: ocean biogeochemical models; global carbon cycle; ocean acidification
Research affiliation: OceanRep > GEOMAR > FB2 Marine Biogeochemistry > FB2-BM Biogeochemical Modeling
Date Deposited: 08 Oct 2012 07:00
Last Modified: 08 Oct 2012 07:00

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