Impact of Siberian observations on the optimization of surface CO2 flux.

To investigate the effect of additional CO₂ observations in the Siberia region on the Asian and global surface CO₂ flux analyses, two experiments using different observation dataset were performed. One experiment was conducted using a data set that includes additional observations of Siberian tower measurements (Japan-Russia Siberian Tall Tower Inland Observation Network: JR-STATION), and the other experiment was conducted using a data set without the above additional observations. The results show that the global balance of the sources and sinks of surface CO₂ fluxes was maintained for both experiments with and without the additional observations. While the magnitude of the optimized surface CO₂ flux uptake in Siberia decreased, the magnitude of the optimized surface CO₂ flux uptake in the other regions (e.g., Europe) of the Northern Hemisphere (NH) increased for the experiment with the additional observations. This change was mostly caused by changes in the magnitudes of surface CO₂ flux in June and July. The observation impact measured by uncertainty reduction and self-sensitivity tests shows that additional observations provide useful information on the estimated surface CO₂ flux. It is expected that the Siberian observations play an important role in estimating surface CO₂ flux in the NH in the future. [ABSTRACT FROM AUTHOR]