WP3: Global scale modelling and feedbacks on Earth system processes

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WP3-1 Reservoir and lake effect on carbon fluxes through the land-ocean aquatic continuum

Specific objectives: The ESR will quantify the effect of large lakes and reservoirs on CO2 evasion, carbon burial and export from the fluvial system. First, a global high resolution map (0.5°) of lake CO2 evasion based on empirical relationships will be derived using the advanced statistical methods and GIS techniques (e.g. that of Lauerwald et al., 2013, FEE) in cooperation with UU. Second, the effects of large lakes and river damming on CO2 evasion and POC burial will be implemented into the IPSL land-surface scheme ORCHIDOC (see ESR14 project description). The Global Reservoir and Dam database (Lehner et al., 2011, FEE) will be incorporated into the river routing scheme of ORCHIDOC, and combined with parameterizations of water residence times and POC trapping rates in lakes and reservoirs. Third, the ‘no-dam’ versus ‘dam’ scenarios will be run to quantify the effects of hydrological alterations on the carbon balance of the LOAC under different land-use and climate conditions.

Expected Results: Quantification of the effects of lakes and dams along the LOAC based on data synthesis and the ORCHIDOC model.

Host institution: ULB ; Secondments:  UU, UNEXE and GCP

Primary Supervisor: Prof. P. Regnier (ULB); Secondary Supervisors: Ass. Prof. S. Sobek and Prof. G. Weyhenmeyer (UU), Prof. T. Quine (UNEXE), Dr. J. Canadell (GCP)

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WP3-2  Carbon burial, benthic-pelagic coupling and feedbacks on the global C cycle

Specific objectives: Despite the key role of sediments in the boundless C cycle, there are only a few rough estimates of how much total and, in particular, terrestrial C is buried in sediments along the land-ocean continuum. Here it is propose to (re)evaluate the C fluxes and, in particular, terrestrial C consumption and burial in sediments, as well as associated benthic-pelagic fluxes of nutrients, oxygen, dissolved carbon and alkalinity on both regional and global scales. For this purpose the ESR will develop a neural network approach to create a numerically efficient encapsulation of a mechanistic, fully coupled, vertically resolved diagenetic model (the BRNS model). The efficient benthic model will then be a) directly coupled to a regional scale model of the Amazon plume (see ESR8 project description) to quantify C consumption/burial and benthic-pelagic exchange fluxes in this key region and their response to anthropogenic perturbations and b) used in combination with global observations/simulation results to re-evaluate these fluxes.

Expected Results: Quantification of C consumption and burial fluxes, and associated benthic exchange fluxes on local and global scale using a coupled benthic-pelagic model, data and a standalone benthic model. Development of a standalone, numerically efficient benthic model.

Host institution: UNIVBRIS ; Secondment: ETHZ

Primary Supervisor: Dr. Sandra Arndt (UNIVBRIS); Secondary Supervisor: Prof. Timothy I. Eglinton (ETHZ)

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WP3-3  Representation of lateral transfer of Dissolved Organic Carbon (DOC) from land to the river system in JULES

Specific objectives: The current version of JULES, the land surface model of the Met Office Hadley Centre Earth system model does not account for export of carbon from terrestrial ecosystems to the aquatic environments. Runoff is represented in the model as river routing to the ocean, without including transfer of carbon. The aim of the project is to include a representation of DOC production in terrestrial soils, due to incomplete decomposition of organic matter, and its export to the river network by leaching. The model will be evaluated using river discharge DOC data for large rivers across the world, with a focus on a specific region (Arctic or Tropics). Simulations will be performed with the major historical forcing (climate, atmospheric CO2, nitrogen deposition, and land-use changes) in order to estimate the changes of DOC export and their attribution to anthropogenic activities.

Expected Results: Quantification of DOC and POC fluxes from land surface to the ocean in JULES and attribution of changes in these fluxes to anthropogenic activities.

Host institution: UNEXE Secondment(s): CNRS-IPSL

Primary Supervisor: Prof. P. Friedlingstein (UNEXE); Secondary Supervisors: Dr. B. Guenet and Prof. P. Ciais (CNRS-IPSL)

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WP3-4  Modelling dissolved organic carbon river transport at global scale in the ORCHIDEE process based land surface model, from soils emissions to estuaries

Specific objectives: The ESR will work on the incorporation of a set of parameterizations in ORCHIDOC, the new version of the land surface scheme of the IPSL Earth system model. New mechanisms including DOC emissions from soils, and their transport through rivers to the ocean, as well as POC export due to soil erosion and decomposition in rivers will be included. Parameterization of DOC decomposition will use empirical functions calibrated from incubation experiments. The DOC transport from soil to rivers will be calibrated against the COSCAT database. The soil erosion will employ the approach of the SWAT model. The soil component will be tested against the DOC concentrations in soil profiles for the main biomes of the globe (Camino Serrano et al., in press, GBC). The effect of land-use change on DOC and POC export will be assessed in collaboration with ULB. The focus will be on boreal and arctic regions using the ORCHIDEE –SOM and –MICT model versions.

Expected Results: Quantification of DOC and POC fluxes from land surface to the ocean in land surface scheme ORCHIDOC.

Host institution: CRNS-IPSL Secondment(s): ULB

Primary Supervisor: Prof. P. Ciais (CNRS-IPSL); Secondary Supervisors: Prof. P. Regnier (ULB)

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WP3-5  Global and regional contribution of riverine fluxes to ocean carbon and nutrient cycling

Specific objectives: The role of riverine fluxes in the marine cycles of carbon and nutrients will be investigated within the Max Planck Institute Earth System Model (MPG-ESM). The ESR will incorporate riverine fluxes of carbon and nutrients into HAMOCC, the ocean biogeochemical component of MPG-ESM. HAMOCC will be extended and improved to include crucial coastal processes and interactions at the coastal – open ocean interface, including the recycling and trapping of the river-borne matter with the coastal zone and remobilization from the upper sediments. This project will constrain the fate of multiform riverine fluxes of carbon and nutrients in the coastal ocean and beyond. Sensitivity of the oceanic cycles of carbon and nutrients to variability and changes in hydrological regimes and in riverine loads will be investigated over the historical period and in future climate change projections.

Expected Results: Quantification of the role of riverine fluxes and coastal – open ocean interface in the marine cycles of carbon and nutrients.

Host institution: MPG Secondment(s): DELTARES

Primary Supervisor: Dr. T. Ilyina (MPG); Secondary Supervisor: Dr. Sacha De Rijk (Deltares)

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