High Arctic aircraft measurements characterising black carbon vertical variability in spring and summer

• Published in: Atmospheric Chemistry and Physics
• Main Authors: Schulz, Hannes, Zanatta, Marco, Bozem, Heiko, Leaitch, W. Richard, Herber, Andreas, Burkhart, Julia, Willis, Megan D., Kunkel, Daniel, Hoor, Peter M., Abbatt, Jonathan P.D., Gerdes, Rüdiger
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: 2019
• Subjects: Arctic; black carbon
• Online Access: https://epic.awi.de/id/eprint/49194/; https://epic.awi.de/id/eprint/49194/1/acp-19-2361-2019.pdf; https://hdl.handle.net/10013/epic.caba0a25-e4bf-49e0-9eee-fea1912b1ea0

The vertical distribution of black carbon (BC) par- ticles in the Arctic atmosphere is one of the key parameters controlling their radiative forcing and thus role in Arctic cli- mate change. This work investigates the presence and prop- erties of these light-absorbing aerosols over the High Cana- dian Arctic ( > 70 degree N). Airborne campaigns were performed as part of the NETCARE project (Network on Climate and Aerosols: Addressing Key Uncertainties in Remote Canadian Environments) and provided insights into the variability of the vertical distributions of BC particles in summer 2014 and spring 2015. The observation periods covered evolutions of cyclonic disturbances at the polar front, which favoured the transport of air pollution into the High Canadian Arctic, as otherwise this boundary between the air masses largely im- pedes entrainment of pollution from lower latitudes. A total of 48 vertical profiles of refractory BC (rBC) mass concen- tration and particle size, extending from 0.1 to 5.5 km altitude were obtained with a Single-Particle Soot Photometer (SP2). Generally, the rBC mass concentration decreased from spring to summer by a factor of 10. Such depletion was as- sociated with a decrease in the mean rBC particle diameter, from approximately 200 to 130 nm at low altitude. Due to the very low number fraction, rBC particles did not substantially contribute to the total aerosol population in summer. The analysis of profiles with potential temperature as ver- tical coordinate revealed characteristic variability patterns within specific levels of the cold and stably stratified, dome- like, atmosphere over the polar region. The associated his- tory of transport trajectories into each of these levels showed that the variability was induced by changing rates and effi- ciencies of rBC import. Generally, the source areas affecting the polar dome extended southward with increasing potential temperature (i.e. altitude) level in the dome. While the lower dome was mostly only influenced by low-level transport ...