CMP2 – Integrating global carbon observations into improved CCDAS
An important challenge in monitoring the current global carbon cycle is the reliable integration of multiple data streams on the carbon cycle of the land, oceans and atmosphere. An integrated carbon cycle assessment would be consistent with the observed atmospheric CO2 gradients and trends, with in situ (i.e FLuxNet) and remote sensing (i.e. FAPAR, forest biomass) constraints on the land ecosystem functioning, with observations of dissolved carbon in the surface and interior ocean, and with latest estimates of fossil fuel and land-use related carbon sources.
The strength of using global data assimilation systems (CCDAS) rather than specific carbon assessment tools for an individual country or ecosystem will allow to i) explicitly uses integrated information from atmospheric mixing ratios at large scale, ii) account for inflow/outflow of carbon for regional carbon balances, and iii) provide new information for the verification of national carbon balances together with uncertainty assessments.
We will use a limited number (N=5) of global data assimilation systems that have demonstrated the ability to simultaneously integrate models and observations of the atmosphere, ocean, and land carbon cycle (see Figure below). Most systems will consider the optimization of key parameters of the underlying land/ocean carbon cycle models to provide new predictive capabilities and process attribution skills, except one system keeping the direct optimization of surface carbon fluxes as a complementary approach. In addition, two efforts are included on assimilating more specialized datasets into ocean-only process models, while two of the global systems will additionally estimate balances for specifically the continents South America and Africa. Two separate country scale CCDAS efforts will provide an important link between the current state-of-the-art global systems and the systems envisioned in the near future (2015-2020) that will operate at much higher spatial resolution, and more strongly target regional process attribution than continental carbon balances.
In summary, the main objectives of this component are thus to (see figure below):
- Reliably integrate multiple data streams of the global carbon cycle (in particular new forest carbon monitoring efforts) to constrain carbon exchange between land, ocean, and atmosphere;
- Derive robust estimates of global carbon exchange using a diverse set of land and ocean CCDAS systems;
- Benchmark quantitatively the individual CCDAS systems against independent data;
- Synthesize the CCDAS results and estimate multiple system confidence bounds;
- Analyze the resulting global carbon balance, carbon stocks, and carbon process contributions with respect to recent scientific insights;
- Derive integrated carbon balances for South America and Africa using newly obtained data streams from CMP4;
- Connect global carbon balance results to national scale efforts as a pioneering step to future national carbon balance verification systems.
Diagram to illustrate the interplay between the different tasks of Component 2 and the links with the other Components (in this figure the project Components are indicated as ‘C’).