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Abstract:
The Siberian region is still sparsely covered by ecosystem observatories, which motivates
to exploit existing datasets to gain spatially and temporally better-resolved carbon
fluxes. The Zotino Tall Tower Observatory (ZOTTO, 60480 N, 89210 E) observations of
5 CO2 and CH4 mole fractions as well as meteorological parameters from six different
heights up to 301m allow for an additional estimate of surface-atmosphere fluxes of
CO2 and CH4 for the Middle-Siberian region since 2009. The total carbon flux is calculated
from the storage and the turbulent flux component. The gradients between the
different tower levels determine the storage flux component, which dominates the local
10 fluxes, especially during night. As a correction term, the turbulent flux component was
estimated by the modified Bowen ratio method based on the sensible heat flux measurements
at the top of the tower. The gained average night time fluxes (23:00 to 04:00
local time) are 2.7±1.1 μmol (m2 s)−1 for CO2 and 5.6±4.5 nmol (m2 s)−1 for CH4 during
the summer months June-September in 2009 and 2011. During day, the method
15 is limited due to numeric instabilities from vanishing vertical gradients; however, the
derived CO2 fluxes exhibit reasonable diurnal shape and magnitude compared to the
eddy covariance technique, which become available at the site in 2012. Therefore, the
tall tower data facilitates the extension of the new eddy covariance flux dataset back
in time. The diurnal signal of the CH4 flux is predominantly characterized by a strong
20 morning transition, which is explained by local topographic effects.
