scholarly journals MESMO 3: Flexible phytoplankton stoichiometry and refractory DOM

2021 ◽  
Author(s):  
Katsumi Matsumoto ◽  
Tatsuro Tanioka ◽  
Jacob Zahn
Keyword(s):  
Organic Matter ◽  
Earth System Model ◽  
System Model ◽  
Earth System ◽  
Temperature Dependent ◽  
Potential Growth ◽  
The Past ◽  
Phosphate Nitrate ◽  
Residual Nitrate ◽  
Environmental Dependence

Abstract. We describe the third version of Minnesota Earth System Model for Ocean biogeochemistry (MESMO 3), an earth system model of intermediate complexity, with a dynamical ocean, a dynamic-thermodynamic sea ice, and an energy moisture balanced atmosphere. A major feature of Version 3 is the flexible C : N : P ratio for the three phytoplankton functional types represented in the model. The flexible stoichiometry is based on the power law formulation with environmental dependence on phosphate, nitrate, temperature, and light. Other new features include nitrogen fixation, water column denitrification, oxygen and temperature-dependent organic matter remineralization, and CaCO3 production based on the concept of the residual nitrate potential growth. Also, we describe the semi-labile and refractory dissolved organic pools of C, N, P, and Fe that can be enabled in MEMSO 3 as an optional feature. The refractory dissolved organic matter can be degraded by photodegradation at the surface and hydrothermal vent degradation at the bottom. These improvements provide a basis for using MESMO 3 in further investigations of the global marine carbon cycle to changes in the environmental conditions of the past, present, and future.

scholarly journals MESMO 3: Flexible phytoplankton stoichiometry and refractory dissolved organic matter

2021 ◽  
Vol 14 (4) ◽  
pp. 2265-2288
Author(s):  
Katsumi Matsumoto ◽  
Tatsuro Tanioka ◽  
Jacob Zahn
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Earth System Model ◽  
System Model ◽  
Earth System ◽  
Temperature Dependent ◽  
Potential Growth ◽  
Phosphate Nitrate ◽  
Residual Nitrate ◽  
Environmental Dependence

Abstract. We describe the third version of Minnesota Earth System Model for Ocean biogeochemistry (MESMO 3), an Earth system model of intermediate complexity, with a dynamical ocean, dynamic–thermodynamic sea ice, and an energy–moisture-balanced atmosphere. A major feature of version 3 is the flexible C:N:P ratio for the three phytoplankton functional types represented in the model. The flexible stoichiometry is based on the power law formulation with environmental dependence on phosphate, nitrate, temperature, and light. Other new features include nitrogen fixation, water column denitrification, oxygen and temperature-dependent organic matter remineralization, and CaCO3 production based on the concept of the residual nitrate potential growth. In addition, we describe the semi-labile and refractory dissolved organic pools of C, N, P, and Fe that can be enabled in MESMO 3 as an optional feature. The refractory dissolved organic matter can be degraded by photodegradation at the surface and hydrothermal vent degradation at the bottom. These improvements provide a basis for using MESMO 3 in further investigations of the global marine carbon cycle to changes in the environmental conditions of the past, present, and future.

scholarly journals Calibration of key temperature-dependent ocean microbial processes in the cGENIE.muffin Earth system model

2020 ◽  
Author(s):  
Katherine Anne Crichton ◽  
Jamie Devereux Wilson ◽  
Andy Ridgwell ◽  
Paul N. Pearson
Keyword(s):  
Organic Matter ◽  
Carbon Cycling ◽  
Surface Waters ◽  
Numerical Models ◽  
Nutrient Supply ◽  
Earth System Model ◽  
System Model ◽  
Earth System ◽  
Temperature Dependent ◽  
Poc Export

Abstract. Temperature is a master parameter in the marine carbon cycle, exerting a critical control on the rate of biological transformation of a variety of solid and dissolved reactants and substrates. Although in the construction of numerical models of marine carbon cycling, temperature has been long-recognised as a key parameter in the production and export of organic matter at the ocean surface, it is much less commonly taken into account in the ocean interior. There, bacteria (primarily) transform sinking particulate organic matter into its dissolved constituents and thereby consume dissolved oxygen (and/or other electron acceptors such as sulphate) and release nutrients, which are then available for transport back to the surface. Here we present and calibrate a more complete temperature-dependent representation of marine carbon cycling in the cGENIE.muffin Earth system model, intended for both past and future climate applications. In this, we combine a temperature-dependent remineralisation scheme for sinking organic matter with a biological export production scheme that also includes a temperature-dependent limitation on nutrient uptake in surface waters (and hence phytoplankton growth). Via a parameter ensemble, we jointly calibrate the two parameterisations by statistically contrasting model projected fields of nutrients, oxygen, and the stable carbon isotopic signature (δ13C) of dissolved inorganic carbon in the ocean, with modern observations. We find that for the present-day, the temperature-dependent version shows as-good-as or better fit to data than the existing tuned non-temperature dependent version of the cGENIE.muffin. The main impact of adding temperature-dependent remineralisation is in driving higher rates of remineralisation in warmer waters and hence a more rapid return of nutrients to the surface there – stimulating organic matter production. As a result, more organic matter is exported below 80 m in mid and low latitude warmer waters as compared to the standard model. Conversely, at higher latitudes, colder water temperature reduces the rate of nutrient supply to the surface as a result of slower in-situ rates of remineralisation. We also assess the implications of including a more complete set of temperature-dependent parameterisations by analysing a series of historical transient experiments. We find that between the pre-industrial and the present day, in response to a simulated air temperature increase of 0.9 °C and ocean warming of 0.12 °C (0.6 °C in surface waters and 0.02 °C in deep waters), a reduction in POC export at 80 m of just 0.3 % occurs. In contrast, with no assumed temperature-dependent biological processes, global POC export at 80 m falls by 2.9 % between the pre-industrial and present day as a consequence of ocean stratification and reduced nutrient supply to the surface. This suggests that increased nutrient recycling in warmer conditions offsets some of the stratification-induced surface nutrient limitation in a warmer world, and that less carbon (and nutrients) then reaches the inner and deep ocean. This extension to the cGENIE.muffin Earth system model provides it with additional capabilities in addressing marine carbon cycling in warmer past and future worlds.

scholarly journals OMEN-SED 0.9: A novel, numerically efficient organic matter sediment diagenesis module for coupling to Earth system models

2018 ◽  
Author(s):  
Dominik Hülse ◽  
Sandra Arndt ◽  
Stuart Daines ◽  
Pierre Regnier ◽  
Andy Ridgwell
Keyword(s):  
Organic Matter ◽  
Marine Sediments ◽  
Earth System Model ◽  
System Model ◽  
Earth System ◽  
Model Framework ◽  
System Models ◽  
Wide Range ◽  
Earth System Models ◽  
Sediment Model

Abstract. We present the first version of OMEN-SED (Organic Matter ENabled SEDiment model), a new, one-dimensional analytical early diagenetic model resolving organic matter cycling and associated biogeochemical dynamics in marine sediments designed to be coupled to Earth system models. OMEN-SED explicitly describes organic matter (OM) cycling as well as associated dynamics of the most important terminal electron acceptors (i.e. O2, NO3, SO4) and methane (CH4), related reduced substances (NH4, H2S), macronutrients (PO4) and associated pore water quantities (ALK, DIC). Its reaction network accounts for the most important primary and secondary redox reactions, equilibrium reactions, mineral dissolution and precipitation, as well as adsorption and desorption processes associated with OM dynamics that affect the dissolved and solid species explicitly resolved in the model. To represent a redox-dependent sedimentary P cycle we also include a representation of the formation and burial of Fe-bound P and authigenic Ca-P minerals. Thus, OMEN-SED is able to capture the main features of diagenetic dynamics in marine sediments and, therefore, offers similar predictive abilities than a complex, numerical diagenetic model. Yet, its computational efficiency allows its coupling to global Earth system models and therefore the investigation of coupled global biogeochemical dynamics over a wide range of climate relevant timescales. This paper provides a detailed description of the new sediment model, an extensive sensitivity analysis, as well as an evaluation of OMEN-SED's performance through comprehensive comparisons with observations and results from a more complex numerical model. We find solid phase and dissolved pore water profiles for different ocean depths are reproduced with good accuracy and simulated terminal electron acceptor fluxes fall well within the range of globally observed fluxes. Finally, we illustrate its application in an Earth system model framework by coupling OMEN-SED to the Earth system model cGENIE and tune the OM degradation rate constants to optimise the fit of simulated benthic OM contents to global observations. We find simulated sediment characteristics of the coupled model framework, such as OM degradation rates, oxygen penetration depths and sediment-water interface fluxes are generally in good agreement with observations and in line with what one would expect on a global scale. Coupled to an Earth system model, OMEN-SED is thus a powerful tool that will not only help elucidate the role of benthic-pelagic exchange processes in the evolution and, in particular, the termination of a wide range of climate events, but will also allow a direct comparison of model output with the sedimentary record – the most important climate archive on Earth.

Emergent constraints on the Southern Ocean anthropogenic carbon and heat uptake

2021 ◽  
Author(s):  
Thomas Frölicher ◽  
Jens Terhaar ◽  
Fortunat Joos
Keyword(s):  
Southern Ocean ◽  
Ocean Circulation ◽  
Earth System Model ◽  
System Model ◽  
Carbon Uptake ◽  
Earth System ◽  
Excess Heat ◽  
The Past ◽  
Heat Uptake ◽  
Anthropogenic Carbon

<p>The Southern Ocean south of 30°S, occupying about a third of global surface ocean area, accounts for approximately 40% of the past anthropogenic carbon uptake and about 75% of excess heat uptake by the ocean. However, Earth system models have large difficulties in reproducing the Southern Ocean circulation, and therefore its historical and future anthropogenic carbon and excess heat uptake. In the first part of the talk, we show that there exists a tight relation across two Earth system model ensembles (CMIP5 and CMIP6) between present-day sea surface salinity in the subtropical-polar frontal zone, the formation region of mode and intermediate waters, and the past and future anthropogenic carbon uptake in the Southern Ocean. By using observations and Earth system model results, we constrain the projected cumulative Southern Ocean anthropogenic carbon uptake over 1850-2100 by the CMIP6 model ensemble to 158 ± 6 Pg C under the low-emissions scenario SSP1-2.6 and to 279 ± 14 Pg C under the high emissions scenario SSP5-8.5. Our results suggest that the Southern Ocean anthropogenic carbon sink is 14-18% larger and 46-54% less uncertain than estimated by the unconstrained CMIP6 Earth system model results. The identified constraint demonstrated the importance of the freshwater cycle for the Southern Ocean circulation and carbon cycle. In the second part of the talk, potential emergent constraints for the Southern Ocean excess heat uptake will be discussed.</p>

Ocean carbon cycle during the last deglaciation in the Max Planck Institute Earth System Model

2020 ◽  
Author(s):  
Bo Liu ◽  
Katharina Six ◽  
Tatiana Ilyina
Keyword(s):  
Organic Matter ◽  
Marine Sediment ◽  
Water Discharge ◽  
Earth System Model ◽  
System Model ◽  
Earth System ◽  
Dust Deposition ◽  
Max Planck ◽  
Terrestrial Organic Matter ◽  
The Impact

<p>The deglacial atmospheric CO2 increase has been attributed to a combination of mechanisms, many of which relate to the ocean outgassing triggered by changing marine physical and biogeochemical states. To quantify the impact of proposed processes and feedback on the deglacial CO2 rise, previous modelling studies mostly conducted time-slice sensitivity experiments. Here, we present results from a transient deglaciation simulation (24 kB.P. - 1850) using the comprehensive Max Planck Institute Earth System Model (MPI-ESM). We force the model with the deglacial atmospheric greenhouse gases (CO2, CH4, N2O) concentrations, obital parameters, ice sheet reconstruction and transient dust deposition. The ocean biogeochemical component of MPI-ESM is using the same automatical adjustment of bathymetry and land-sea mask in response to deglacial continental runoff and melt water discharge. In and around the areas of changing land-sea mask, we redistribute the marine biogeochemical tracers in accord with the simulated salinity. Terrestrial organic matter is transferred from flooded land areas to the ocean, which guarantees mass conservation with respect to carbon. We also include 13C tracers in the ocean biogeochemical component to evaluate the simulated ocean state against proxy data. The initial marine nutrients and carbon inventories are set the same as those in the present-day ocean. <br>During the first 3 kyr, the climate and ocean state show, as expected, only modest variations. Some flooding events of coastal areas bring terrestrial organic matter to the ocean and lead locally to CO2 outgassing for several decades. Terrestrial organic matter has a higher carbon to nutrient stoichiometry as compared to marine organic matter, thus its remineralization favours CO2 outgassing. Additionally, the accumulation of terrestrial organic matter in the top layers of the marine sediment reduces the replenishment of the water-column nutrients by the re-flux of remineralization products from marine sediment. Consequently, the strength of the local biological pump decreases. Further results will be presented and discussed. </p>

scholarly journals Variable C : N : P stoichiometry of dissolved organic matter cycling in the Community Earth System Model

2014 ◽  
Vol 11 (6) ◽  
pp. 9071-9101 ◽  
Author(s):  
R. T. Letscher ◽  
J. K. Moore ◽  
Y.-C. Teng ◽  
F. Primeau
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
General Circulation ◽  
General Circulation Models ◽  
Ocean Model ◽  
Earth System Model ◽  
System Model ◽  
Earth System ◽  
Organic C ◽  
Community Earth System Model

Abstract. Dissolved organic matter (DOM) plays an important role in the ocean's biological carbon pump by providing an advective/mixing pathway for ~ 20% of export production. DOM is known to have a stoichiometry depleted in nitrogen (N) and phosphorus (P) compared to the particulate organic matter pool, a~fact that is often omitted from biogeochemical-ocean general circulation models. However the variable C : N : P stoichiometry of DOM becomes important when quantifying carbon export from the upper ocean and linking the nutrient cycles of N and P with that of carbon. Here we utilize recent advances in DOM observational data coverage and offline tracer-modeling techniques to objectively constrain the variable production and remineralization rates of the DOM C / N / P pools in a simple biogeochemical-ocean model of DOM cycling. The optimized DOM cycling parameters are then incorporated within the Biogeochemical Elemental Cycling (BEC) component of the Community Earth System Model and validated against the compilation of marine DOM observations. The optimized BEC simulation including variable DOM C : N : P cycling was found to better reproduce the observed DOM spatial gradients than simulations that used the canonical Redfield ratio. Global annual average export of dissolved organic C, N, and P below 100 m was found to be 2.28 Pg C yr−1 (143 Tmol C yr−1), 16.4 Tmol N yr−1, and 1 Tmol P yr−1, respectively with an average export C : N : P stoichiometry of 225 : 19 : 1 for the semilabile (degradable) DOM pool. DOC export contributed ~ 25% of the combined organic C export to depths greater than 100 m.

scholarly journals Variable C : N : P stoichiometry of dissolved organic matter cycling in the Community Earth System Model

2015 ◽  
Vol 12 (1) ◽  
pp. 209-221 ◽  
Author(s):  
R. T. Letscher ◽  
J. K. Moore ◽  
Y.-C. Teng ◽  
F. Primeau
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
General Circulation ◽  
General Circulation Models ◽  
Ocean Model ◽  
Earth System Model ◽  
System Model ◽  
Earth System ◽  
Organic C ◽  
Community Earth System Model

Abstract. Dissolved organic matter (DOM) plays an important role in the ocean's biological carbon pump by providing an advective/mixing pathway for ~ 20% of export production. DOM is known to have a stoichiometry depleted in nitrogen (N) and phosphorus (P) compared to the particulate organic matter pool, a fact that is often omitted from biogeochemical ocean general circulation models. However the variable C : N : P stoichiometry of DOM becomes important when quantifying carbon export from the upper ocean and linking the nutrient cycles of N and P with that of carbon. Here we utilize recent advances in DOM observational data coverage and offline tracer-modeling techniques to objectively constrain the variable production and remineralization rates of the DOM C : N : P pools in a simple biogeochemical-ocean model of DOM cycling. The optimized DOM cycling parameters are then incorporated within the Biogeochemical Elemental Cycling (BEC) component of the Community Earth System Model (CESM) and validated against the compilation of marine DOM observations. The optimized BEC simulation including variable DOM C : N : P cycling was found to better reproduce the observed DOM spatial gradients than simulations that used the canonical Redfield ratio. Global annual average export of dissolved organic C, N, and P below 100 m was found to be 2.28 Pg C yr−1 (143 Tmol C yr−1, 16.4 Tmol N yr−1, and 1 Tmol P yr−1, respectively, with an average export C : N : P stoichiometry of 225 : 19 : 1 for the semilabile (degradable) DOM pool. Dissolved organic carbon (DOC) export contributed ~ 25% of the combined organic C export to depths greater than 100 m.

scholarly journals Climate Variability and Change since 850 CE: An Ensemble Approach with the Community Earth System Model

2016 ◽  
Vol 97 (5) ◽  
pp. 735-754 ◽  
Author(s):  
Bette L. Otto-Bliesner ◽  
Esther C. Brady ◽  
John Fasullo ◽  
Alexandra Jahn ◽  
Laura Landrum ◽  
...  
Keyword(s):  
Climate Variability ◽  
Ice Cores ◽  
Volcanic Eruptions ◽  
Internal Variability ◽  
Earth System Model ◽  
System Model ◽  
Earth System ◽  
The Past ◽  
Community Earth System Model ◽  
Past Millennium

Abstract The climate of the past millennium provides a baseline for understanding the background of natural climate variability upon which current anthropogenic changes are superimposed. As this period also contains high data density from proxy sources (e.g., ice cores, stalagmites, corals, tree rings, and sediments), it provides a unique opportunity for understanding both global and regional-scale climate responses to natural forcing. Toward that end, an ensemble of simulations with the Community Earth System Model (CESM) for the period 850–2005 (the CESM Last Millennium Ensemble, or CESM-LME) is now available to the community. This ensemble includes simulations forced with the transient evolution of solar intensity, volcanic emissions, greenhouse gases, aerosols, land-use conditions, and orbital parameters, both together and individually. The CESM-LME thus allows for evaluation of the relative contributions of external forcing and internal variability to changes evident in the paleoclimate data record, as well as providing a longer-term perspective for understanding events in the modern instrumental period. It also constitutes a dynamically consistent framework within which to diagnose mechanisms of regional variability. Results demonstrate an important influence of internal variability on regional responses of the climate system during the past millennium. All the forcings, particularly large volcanic eruptions, are found to be regionally influential during the preindustrial period, while anthropogenic greenhouse gas and aerosol changes dominate the forced variability of the mid- to late twentieth century.

scholarly journals Oceanic CO<sub>2</sub> outgassing triggered by terrestrial organic carbon fluxes during deglacial flooding

2021 ◽  
Author(s):  
Thomas Extier ◽  
Katharina D. Six ◽  
Bo Liu ◽  
Hanna Paulsen ◽  
Tatiana Ilyina
Keyword(s):  
Organic Matter ◽  
Model Development ◽  
Co2 Flux ◽  
Earth System Model ◽  
System Model ◽  
Global Ocean ◽  
Earth System ◽  
Last Deglaciation ◽  
Max Planck ◽  
Terrestrial Organic Matter

Abstract. Oceans play a major role on the exchange of carbon with the atmosphere and thereby on past climates with glacial/interglacial variations of the CO2 concentration. The melting of ice sheets during deglaciations lets the sea level rise which leads to the flooding of coastal land areas resulting in the transfer of terrestrial organic matter to the ocean. However, the consequences of such fluxes on the ocean biogeochemical cycle and uptake/release of CO2 are poorly constrained. Moreover, this potentially important exchange of carbon at the land-sea interface is not represented in most Earth System Models. We present here the implementation of terrestrial organic matter fluxes into the ocean at the transiently changing land-sea interface in the Max Planck Institute for Meteorology Earth System Model (MPI-ESM) and investigate their effect on the biogeochemistry during the last deglaciation. Our results show that during the deglaciation, most of the terrestrial organic matter inputs to the ocean occurs during Meltwater Pulse 1a (between 15–14 ka) which leads to additional 21.2 GtC of terrestrial origin (mostly originating from wood and humus). Although this additional organic matter input is relatively small in comparison to the global ocean inventory (0.06 %) and thus doesn’t have an impact on the global CO2 flux, the terrestrial organic matter fluxes initiate oceanic outgassing at regional hotspots like in Indonesia for a few hundred years. Finally, sensitivity experiments highlight that terrestrial organic matter fluxes are the drivers of oceanic outgassing in flooded coastal regions during Meltwater Pulse 1a. Furthermore, the magnitude of outgassing is rather insensitive to higher carbon to nutrients ratios of the terrestrial organic matter. Our results provide a first estimate of the importance of terrestrial organic matter fluxes in a transient deglaciation simulation. Moreover, our model development is an important step towards a fully coupled carbon cycle in an Earth System Model applicable for simulations of glacial/interglacial cycles.

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