Patterns of CO₂and radiocarbon across high northern latitudes during International Polar Year 2008

Abstract

[1] High-resolution in situ CO 2 measurements were conducted aboard the NASA DC-8 aircraft during the ARCTAS/POLARCAT field campaign, a component of the wider [2007][2008] International Polar Year activities. Data were recorded during large-scale surveys spanning the North American sub-Arctic to the North Pole from 0.04 to 12 km altitude in spring and summer of 2008. Influences on the observed CO 2 concentrations were investigated using coincident CO, black carbon, CH 3 CN, HCN, O 3 , C 2 Cl 4 , and D 14 CO 2 data, and the FLEXPART model. In spring, the CO 2 spatial distribution from 55°N to 90°N was largely determined by the long-range transport of air masses laden with Asian anthropogenic pollution intermingled with Eurasian fire emissions evidenced by the greater variability in the mid-to-upper troposphere. At the receptor site, the enhancement ratios of CO 2 to CO in pollution plumes ranged from 27 to 80 ppmv ppmv −1 with the highest anthropogenic content registered in plumes sampled poleward of 80°N. In summer, the CO 2 signal largely reflected emissions from lightning-ignited wildfires within the boreal forests of northern Saskatchewan juxtaposed with uptake by the terrestrial biosphere. Measurements within fresh fire plumes yielded CO 2 to CO emission ratios of 4 to 16 ppmv ppmv −1 and a mean CO 2 emission factor of 1698 ± 280 g kg

Methane and carbon dioxide fluxes and their regional scalability for the European Arctic wetlands during the MAMM project in summer 2012

“…1), a region with a slightly higher proportion of wetlands (29 %). With a mean PBL mole fraction of 89 ppb for CO and 26 ppt for HCN, both species remained at mole fractions throughout the flight that are representative of a typical background for the summer at these latitudes (Vay et al, 2011;O'Shea et al, 2013a). This indicates that any biomass burning and anthropogenic emissions within the region were small and well-mixed when sampled by the FAAM BAe-146.…”

Airborne observations of trace gases over boreal Canada during BORTAS: campaign climatology, air mass analysis and enhancement ratios

“…These lifetimes are also short enough so that BB emissions are a substantial increase over the ambient concentrations. For these reasons all three species are widely used tracers for BB Hornbrook et al, 2011;Vay et al, 2011).…”

“…A common method to identify BB plumes is to use some combination of HCN, CH 3 CN and CO to partition air masses between those that have, and those that have not, been recently influenced by biomass burning (Hornbrook et al, 2011;Vay et al, 2011;Palmer et al, 2013). A representative threshold concentration value and/or ratio is chosen from tracer-tracer relationships, where the tracer measurements above a certain threshold value are classified as a biomass burning plume.…”

Airborne hydrogen cyanide measurements using a chemical ionisation mass spectrometer for the plume identification of biomass burning forest fires

“…This method is likely to cause inaccuracies as there is no definite point at which "plume data" can be determined. Vay et al (2011) limited the HCN mixing ratio to above 500 pptv, CO to above 160 ppbv and CH 3 CN to above 225 pptv, but again they will experience similar issues with background concentrations. Simpson et al (2011) state that the plume locations are defined by maximum CO concentrations.…”

“…There can be difficulties in filtering out plumes which do not originate from BB. Recent studies implementing these various methods of identifying a BB plume have resulted in an uncertainty in the ratio of HCN to CO due to the variability observed in fires and potential mixing from other sources (Simpson et al, 2011;Vay et al, 2011;Hornbrook et al, 2011;Yokelson et al, 2009 ;Sinha et al, 2003;Andreae and Merlet., 2001). Using measurements of HCN and CO, BB plumes can be uniquely identified; enabling emission factors to be calculated from aircraft measurements.…”