| Summary: | Evaluating the influence of biomass burning on the Arctic requires continuous and long-term measurements of the transported emissions. In this thesis, ground-based Fourier transform infrared (FTIR) solar-absorption spectroscopic measurements at the Polar Environment Atmospheric Research Laboratory (PEARL) in Eureka, Nunavut, Canada from 2006-2018 are used to retrieve the atmospheric abundance of the biomass burning species CO, HCN, C2H6, C2H2, CH3OH, H2CO, HCOOH and NH3 . The retrievals of NH3 from Eureka FTIR measurements are the first long-term ground-based measurements of NH3 in the high Arctic. Measurements of NH3, CO, HCN and C2H6 were simultaneously enhanced in July-August 2014 and attributed to the 2014 Northwest Territories wildfires. Enhancements were observed in FTIR measurements at Toronto, and due to the differences in traveltimes between the sites, an approximate 2-day lifetime of NH3 in a smoke plume was determined, allowing for NH3 to undergo long-range transport and therefore suggesting that boreal wildfires may be a considerable episodic NH3 source to the Arctic. The greatest enhancements of NH3, CO, HCN, and C2H6 were observed from FTIR measurements at Eureka (2006-2017) and Thule, Greenland (2006-2017) from 17-22 August 2017 and attributed to the 2017 British Columbia and Northwest Territories wild- fires. A GEOS-Chem simulation illustrated that these wildfires contributed to surface-layer NH3 enhancements in the Canadian Archipelago of 0.01-0.11 ppbv from 15-23 August 2017, 0.14-5.50 times the background due to local seabird-colony sources, further indicating that boreal wildfire NH3 is an important episodic source of NH3 in the summertime high Arctic in addition to the persistent seabird-colony source. Detection of wildfire pollution events was performed for Eureka FTIR measurements and nine other Northern high- and mid-latitude Network for the Detection of Atmospheric Composition Change (NDACC) FTIR sites from 2003-2018. Enhancements of CO were detected and correlated with simultaneous enhancements of the biomass burning tracers HCN and C2H6, providing a means of wildfire pollution detection. Source attribution of the detected events was performed using a GEOS-Chem tagged CO simulation. Boreal North America and boreal Asia were the largest contributors to anomalous enhancements at all sites, with a recent increase in the boreal North American contribution from 2013-2018. Ph.D.
|
|---|