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Abstract:
Due to a strong Arctic warming trend, potentially
large greenhouse gas emissions from Arctic and sub-
Arctic areas are of concern. The Lena River Delta
located in north-east Siberia is the largest delta within
the Arctic Circle, characterized by wetland ecosystems
and wet polygonal tundra environments. These
environments are currently thought to be sinks for
carbon dioxide and sources of methane.
Tower-based eddy covariance is the most widely
used direct method for quantifying exchanges of momentum,
energy and trace gases between the surface
and the atmosphere. However, they cover a relatively
small footprint and constitute point measurements
relative to the vast extend of tundra ecosystems. To
improve spatial coverage and spatial representativeness
of these direct flux measurements, airborne eddy
covariance flux measurements across large areas are
required. We used the helicopter-carried measurement
system “Helipod” equipped with a turbulence probe,
fast temperature and humidity sensors, and a fast
response gas analyzer to measure turbulent fluxes of
heat, carbon dioxide, and methane across the Lena
River Delta in Russia in 2012 and 2014. The 2014
campaign covered several periods of the season from
April to August 2014.
Wavelet transforms are used to improve spatial
resolution of the flux measurements and footprint
analysis is applied to find relations between surface
fluxes and biophysically relevant land cover properties.
Strong regional differences in trace gas fluxes
were detected, indicating a non-uniform distribution
of sources especially in wet sedge-, moist grass-, and
moss-dominated tundra. In contrast, the sensible
heat flux showed less variability across the investigation
area. The obtained results are essential in
understanding the role of Arctic ecosystems in the
greenhouse gas budgets and to evaluate regional scale
model simulations.
