Setup of a CO2 and CH4 measurement system in Central Siberia and modeling of its results

To improve the monitoring of the carbon cycle, an automated, low maintenance measurement system has been installed at the Zotino Tall Tower Observatory in Central Siberia (ZOTTO, 60°48′ N, 89°21′ E) in April 2009. A cavity ring-down spectroscopy (CRDS) analyzer continuously measures carbon dioxide (CO₂), methane (CH₄) and water vapor (H₂O) from six heights up to 301 m a.g.l. The measurement precision (accuracy) of 0.04 ppm (0.09 ppm) for CO₂ and 0.3 ppb (1.5 ppb) for CH₄ is compliant with the WMO recommendations. The data collected so far (until June 2011) reveals an increase of 2.62 ppm a^-1 and a seasonal cycle amplitude of 28.3 ppm for CO₂ at the 301m level. In 2010, the heat wave in the European part of Russia had particular impact on the ecosystem, which is also clearly illustrated by the distinct signals in the CO and Aerosol data from the ZOTTO station. Buffer volumes in each sample line allow continuous, near-concurrent measurements from all tower levels with a single analyzer. The gradients between the tower levels have been analyzed in combination with meteorological measurements to estimate diurnal cycles of local CO₂ and CH₄ fluxes for individual summer months, which compare well with previous studies. Finally, the CO₂ and CH₄ observations from the ZOTTO station and 5 other Central Siberian stations have been incorporated into an atmospheric transport inversion model to estimate fluxes for the boreal zone of Central Siberia of 0.04 ± 0.11 Pg carbon through CO₂ and 8.4 ± 1.1 Tg carbon through CH₄ in the year 2009.