Effect of recent observations on Asian CO2 flux estimates by transport model inversions

We use an inverse model to evaluate the effects of the recent CO₂ observations over Asia on estimates of regional CO₂ sources and sinks. Global CO₂ flux distribution is evaluated using several atmospheric transport models, atmospheric CO₂ observations and a “time-independent” inversion procedure adopted in the basic synthesis inversion by the Transcom-3 inverse model intercomparison project. In our analysis we include airborne and tower observations in Siberia, continuous monitoring and airborne observations over Japan, and airborne monitoring on regular flights on Tokyo—Sydney route. The inclusion of the new data reduces the uncertainty of the estimated regional CO₂ fluxes for Boreal Asia (Siberia), Temperate Asia and South-East Asia. The largest effect is observed for the emission/sink estimate for the Boreal Asia region, where introducing the observations in Siberia reduces the source uncertainty by almost half. It also produces an uncertainty reduction for Boreal North America. Addition of the Siberian airborne observations leads to projecting extra sinks in Boreal Asia of 0.2 Pg C yr⁻¹, and a smaller change for Europe. The Tokyo—Sydney observations reduce and constrain the Southeast Asian source.