The future climate of the Earth strongly depends on the capacity of the global ecological system to sequester atmospheric CO2, and on the abundance of stratospheric sulphate aerosols (SSA). These two climate-regulating mechanisms are intricately linked to an atmospheric gas that makes up only a tiny fraction of the Earth's atmosphere, carbonyl sulphide (COS).  The COS-OCS project aims to fundamentally improve our limited understanding of the COS atmospheric budget, by combining innovative modelling and measurements.

http://cos-ocs.eu/

• dr. M.E. (Elena) Popa
• dr. S.L. (Sophie) Baartman

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).