First-year observations of atmospheric black carbon mass concentrations and CO mixing ratios at Poker Flat, central Alaska since April 2016

Long-term observation of atmospheric black carbon (BC) mass concentration and CO mixing ratios at Poker Flat Research Range (PFRR) of the University of Alaska Fairbanks (Alaska, USA; 65.12N, 147.43W; 491 m asl) started on 28 April 2016. BC mass concentration and CO mixing ratios were measured by a continuous short monitoring system (COSMOS) and a nondispersive infrared (NDIR) absorption photometer respectively. Median BC mass concentration (28 April 2016 - 25 February 2017) was 0.013 µg m^-3; high concentrations (>0.3 µg m^-3) were recorded eight times (three in June and singly in July, September, October, December 2016 and January 2017). The observed data were divided according to emission sources – local emission from Alaska forest wildfires and others. Analysis of Alaska fire emission was conducted by using data of Alaska fire information (AICC ArcIMS) and ten-day backward trajectories (HYPSLIT, GDAS1) from Poker Flat. One of the largest fires during the observation period was named as "Big Mud" (Nowitna National Wildlife Refuge, Alaska, USA; 64.5 N, 153.3 W), which burned 44,540 acres (180 km²) about 280 km west of Poker Flat. On 18 June 2016, backward trajectories from Poker Flat (500 m altitude) passed very close to Big Mud fire with median transporting time 96 hours (from 13 to 104 hours). Precipitation during the transport was 0-1.4 mm and its effect on wet removal was expected to be small. Maximums of hourly BC mass concentration and CO mixing ratios were 5.5 µg m^-3 and 1950 ppb respectively for this day and for all period. In February 2017, high levels of BC and CO were displayed – monthly median values of BC and CO were 0.048 µg m^-3and 155 ppb respectively. We will also discuss preliminary comparison results with chemical transport model simulations.