African Carbon Exchange (ACE) Project

ACE utilizes an array of techniques to understand how climate variability and human activities affect continental-scale carbon cycling and atmospheric carbon dioxide concentrations. Using a combination of methods we will provide more tightly constrained estimates of the spatial and temporal variation in carbon uptake and release from the region. The project will: Afriflux

add targeted surface flux and precision [CO2] measurements
add to the Afriflux network with intensive instrumentation at key field sites
incorporate high temporal and spatial resolution satellite data for land surface characterization
parameterize terrestrial carbon balance models that predict spatially and temporally continuous fields of net carbon, water and stable isotope exchange (“forward” modeling)
perform inverse analysis of [CO2] and stable isotope concentrations using the existing flask network augmented by new high precision [CO2] measurements

Terrestrial biospheric contributions to global carbon cycling are poorly understood, particularly for Africa where we have only a few observations of fluxes and concentrations, and large uncertainty regarding ecosystem function, and the roles of fire and land use.

Biogeochemical or biophysical land surface models can be used to supply time-varying, spatially distributed estimates of plant productivity, evapotranspiration, and net ecosystem exchange. However, the models surely provide an imperfect representation of the complex abiotic and biotic interactions involved in surface-atmosphere carbon, water, and energy exchanges.

BambaHFS Analysis of observed CO2 concentrations provides additional information about the global spatial, and seasonal to interannual temporal distribution of its sources and sinks. Yet, the sparse observation network presents an incomplete picture of the true spatial and temporal patterns.

The ACE project employs a multiple constraints approach that merges these techniques. Modeled land-atmosphere exchanges are merged with inverse analysis of measured [CO2] and its likely transport to provide a best estimate of regional sources/sinks and their uncertainty.

The novel combination of forward and inverse approaches will lead to improved estimates of the spatial and temporal dynamics of carbon and water exchange in Africa, and enhance understanding of the impacts of climate, climate variability and land use on carbon exchange and Africa’s contributions to the global carbon cycle.

ABOUT: AFRICAN CARBON EXCHANGE (ACE)