High-Latitude Observations of NMHCs, Halocarbons, and COs during ATom-1 and ATom-2

Nearly pole-to-pole measurements of trace gases, such as we accomplished during the first two NASA Atmospheric Tomography (ATom) field missions, provide a unique research opportunity to compare and contrast the polar regions during different seasons. The spatial distributions 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 1579 whole air samples (WAS) collected during ATom-1 (July-August 2016) and 1643 samples collected during ATom-2 (January-February 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, 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. We will place the observations in the context of previous Arctic (e.g., TOPSE (Feb-May 200), ARCTAS (April and July 2008) and surface measurements (from 1983)) to try to discern changes over time. We will also compare our results to the fewer published measurements for high southern hemisphere latitudes.