Using satellite data of CO and CO₂ to study the atmospheric carbon ballance during draught events

Narcisa Nechita-Banda

Droughts are expected to occur more frequently in the future, due to climate change. Ecosystem response to drought include (i) more frequent occurrence of biomass burning (ii) reduction of carbon uptake and release due to water stress. Both responses lead to positive CO₂ anomalies in the atmosphere. Satellite instruments have detected such drought-related anomalies in CO₂ column abundances. With this project, we expect to disentangle the contributions from fires and water-stress on ecosystems by additional observations of CO total columns from space. These latter observations can be used to quantify the biomass burning contribution by the use of biomass burning CO/CO₂ emission ratios.
We will employ the TM5 4DVAR system that has been developed to optimize surface exchange fluxes (CO, CO₂) using observations. The latest developments of this system allow the use of large streams of satellite data surface observations in a multi-tracer (CO, CO₂) approach, optimizing simultaneously for different exchange processes (Biomass burning, Biosphere).