Publication Date:
2020-06-03
Description:
Among other regions of the world, the Arctic is strongly affected by climate change. Globally, it is the region with the most pronounced warming, leading to permafrost warming and thawing. Part of the 1,300 Pg soil organic carbon currently stored in the frozen ground is already and might be further released as carbon dioxide (CO2) and methane (CH4). CO2 is released through aerobic soil respiration and from plant roots, but also sequestered through photosynthesis. CH4 emission can be attributed to either recent microbial activity or to past microbial or thermal decomposition and is spatially heterogeneous. To our knowledge, regional assessments of the total carbon flux (CO2 and CH4) based on high frequency airborne measurements do not exist. Here we determine the regional pattern of CO2 and total carbon emissions (CO2 + CH4) of the Mackenzie Delta region, Canada, based on the Airborne Measurements of Methane Fluxes Campaign (AIRMETH) in July 2013 [Kohnert et al., 2014]. The Mackenzie Delta is the second largest arctic delta (13,000 km2). Our measurements covered an area extending 320 km from west to east (140°58’ W to 133°22’W) and of 240 km from north to south (69°33’N to 67°26’N). The study area is heterogeneous and comprises the delta itself, the adjacent Yukon coastal plain, and Richards Island north east of the delta. Part of the delta is located north of the treeline. The area surrounding the delta is described as continuous permafrost zone where the permafrost reaches a thickness of 300 m along the coastal plain and 500 m on Richards Island. In the delta itself the discontinuous permafrost reaches a maximum thickness of 100 m. For the AIRMETH campaign we used the research aircraft Polar 5. Equipped with a 5-hole probe, the usual meteorological sensors, and a fast greenhouse gas analyser (GGA 24EP, Los Gatos Research Inc.) we flew at 30 - 60 m above ground at a true airspeed of 60 m s−1. CO2 and CH4 fluxes were calculated with a timefrequency resolved version of the eddy-covariance technique [Metzger et al., 2013]. We calculated flux topographies [Mauder et al., 2008] to resolve the fluxes along a linear flight track to the area within the footprint of the measurements. The result is a 100 m resolved gridded carbon flux map within the footprints of the flight tracks. Based on the flux topographies we produce a map of the regional pattern of peak growing season carbon fluxes.
Language:
English
Type:
info:eu-repo/semantics/conferenceObject
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