Can a drone equipped with a miniature methane sensor determine methane
fluxes from an Alaskan wetland?
Abstract
Methane fluxes are often studied using eddy covariance flux towers or
chambers placed on the soil surface. These measurement techniques have
improved our understanding of methane emissions from wetlands. However,
there are limitations with each measurement method. For example,
chambers are fixed in place and have high maintenance costs, limiting
spatial coverage and characterization of heterogeneity. Measurements
taken in Interior Alaskan wetlands suggest that heterogeneity in methane
fluxes from this region may increase during the fall and early winter,
when the soils begin to freeze. Unfortunately, off-grid power
limitations and freezing conditions complicate chamber operation during
this time. Towers share similar demands with respect to maintenance and
cost of operation, and, therefore, are not often replicated within a
landscape. Moreover, towers provide an integrated measurement which
masks any spatial heterogeneity in fluxes within the tower footprint.
Therefore, although chamber and flux towers provide important insights
into the carbon exchange between terrestrial and atmospheric pools,
these methods have limitations, particularly when characterizing spatial
heterogeneity. We tested a new technology that may be able to be
counteract some of these limitations, thereby providing additional
insights into methane emissions from wetlands. We outfitted a
small-unmanned aerial system (sUAS, or drone), that can fly extremely
close (<2 m) to the wetland’s surface, with a miniature
open-path laser spectrometer methane sensor, LIDAR, and a miniature
anemometer. We then tested this system in several bogs near Fairbanks,
Alaska. We tested if this system could detect spatial and/or temporal
variability of methane emissions within a bog. We also compared methane
fluxes calculated using this system to values obtained from tower and
chamber measurements. Results of these missions will be presented and we
will discuss the ability of this new technology to provide additional
information regarding methane emissions from wetlands.