TITLE

Investigating Alaskan methane and carbon dioxide fluxes using measurements from the CARVE tower

AUTHOR(S)
Karion, A.; Sweeney, C.; Miller, J. B.; Andrews, A. E.; Commane, R.; Dinardo, S.; Henderson, J. M.; Lindaas, J.; Lin, J. C.; Luus, K. A.; Newberger, T.; Tans, P.; Wofsy, S. C.; Wolter, S.; Miller, C. E.
PUB. DATE
December 2015
SOURCE
Atmospheric Chemistry & Physics Discussions;2015, Vol. 15 Issue 23, p34871
SOURCE TYPE
Academic Journal
DOC. TYPE
Article
ABSTRACT
Northern high-latitude carbon sources and sinks, including those resulting from degrading permafrost, are thought to be sensitive to the rapidly warming climate. Because the near-surface atmosphere integrates surface fluxes over large (~500-1000 km) scales, atmospheric monitoring of carbon dioxide (CO2) and methane (CH4) mole fractions in the daytime mixed layer is a promising method for detecting change in the carbon cycle throughout boreal Alaska. Here we use CO2 and CH4 measurements from a NOAA tower 17 km north of Fairbanks AK, established as part of NASA's Carbon in Arctic Reservoirs Vulnerability Experiment (CARVE), to investigate regional fluxes of CO2 and CH4 for 2012-2014. CARVE was designed to use aircraft and surface observations to better understand and quantify the sensitivity of Alaskan carbon fluxes to climate variability. We use high-resolution meteorological fields from the Polar Weather Research and Forecasting (WRF) model coupled with the Stochastic Time-Inverted Lagrangian Transport model (hereafter, WRF-STILT), along with the Polar Vegetation Photosynthesis and Respiration Model (PolarVPRM), to investigate fluxes of CO2 in boreal Alaska using the tower observations, which are sensitive to large areas of central Alaska. We show that simulated PolarVPRM/WRF-STILT CO2 mole fractions show remarkably good agreement with tower observations, suggesting that the WRF-STILT model represents the meteorology of the region quite well, and that the PolarVPRM flux magnitudes and spatial distribution are consistent with CO2 mole fractions observed at the CARVE tower. CO2 signals at the tower are larger than predicted, with significant respiration occurring in the fall that is not captured by PolarVPRM. Using the WRF-STILT model, we find that average CH4 fluxes in boreal Alaska are somewhat lower than flux estimates by Chang et al. (2014) over all of Alaska for May-September 2012; we also find emissions persist during some wintertime periods, augmenting those observed during the summer and fall. The presence of significant fall and winter CO2 and CH4 fluxes underscores the need for year-round in-situ observations to quantify changes in boreal Alaskan annual carbon balance.
ACCESSION #
111931476

 

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