High Latitude aircraft observations of NMHCs, halocarbons and COS during ATom

Nearly pole-to-pole measurements of trace gases were accomplished during the NASA Atmospheric Tomography (ATom) field missions. These NASA DC-8 aircraft flights provide a unique research opportunity to compare and contrast the polar regions during different seasons. The spatial distributions (including tropospheric profiling) of non-methane hydrocarbons (NMHCs) and other species are key to understanding their sources and sinks, as well as their role in the photochemical production of ozone and secondary organic aerosols (SOA).

We present results from several thousand whole air samples (WAS) collected during ATom-1 (July-August 2016), ATom-2 (January-February 2017), and ATom-3 (September-October 2017). The samples were analyzed using gas chromatography with ECD/FID/Mass Spectrometer detection for 30+ C₂-C₁₀ NMHCs, 26 halocarbons, and carbonyl sulfide (COS).

The Arctic is already experiencing long-term changes as the result of climate change. During ATom-1 the high latitude northern hemisphere exhibited some influence from biomass burning but was relatively clean. During ATom-2 many gases had accumulated in the atmosphere, especially at low altitude, including tracers for combustion and oil/gas activities. The wide variety of the atmospheric lifetimes of such a large suite of gases, combined with back trajectories and model results, allow the measured distributions to be used to estimate source influences. This analysis will be extended to the recent ATom-3 campaign.

We place the observations in context with previous Arctic campaigns e.g., TOPSE (Feb-May 2000) and ARCTAS (April and July 2008), as well as surface measurements for Alaska (from 1983-2012) and for Summit, Greenland. We also compare our results to the few published measurements for high southern hemisphere latitudes.