Arctic black carbon during PAMARCMiP 2018 and previous aircraft experiments in spring

• Published in: Atmospheric Chemistry and Physics
• Main Authors: Ohata, Sho, Koike, Makoto, Yoshida, Atsushi, Moteki, Nobuheri, Adachi, Kouji, Oshima, Naga, Matsui, Hitoshi, Eppers, Oliver, Bozem, Heiko, Zanatta, Marco, Herber, Andreas
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: COPERNICUS GESELLSCHAFT MBH 2021
• Subjects: Arctic; Ny-Ålesund; Station Nord; black carbon; Fram Strait; Ny Ålesund
• Online Access: https://epic.awi.de/id/eprint/54885/; https://epic.awi.de/id/eprint/54885/1/2021_Ohata-Herber-etal_ACP.pdf; https://www.atmospheric-chemistry-and-physics.net; https://hdl.handle.net/10013/epic.91ffd965-b6a2-4165-a57f-cbc25be53deb; https://hdl.handle.net/

Vertical profiles of the mass concentration of black carbon (BC) were measured at altitudes up to 5km dur- ing the PAMARCMiP (Polar Airborne Measurements and Arctic Regional Climate Model simulation Project) aircraft- based field experiment conducted around the northern Green- land Sea (Fram Strait) during March and April 2018 from operation base Station Nord (81.6◦ N, 16.7◦ W). Median BC mass concentrations in individual altitude ranges were 7–18 ng m−3 at standard temperature and pressure at alti- tudes below 4.5km. These concentrations were systemati- cally lower than previous observations in the Arctic in spring, conducted by ARCTAS-A in 2008 and NETCARE in 2015, and similar to those observed during HIPPO3 in 2010. Col- umn amounts of BC for altitudes below 5 km in the Arctic (>66.5◦ N; COLBC), observed during the ARCTAS-A and NETCARE experiments, were higher by factors of 4.2 and 2.7, respectively, than those of the PAMARCMiP experi- ment. These differences could not be explained solely by the different locations of the experiments. The year-to-year variation of COLBC values generally corresponded to that of biomass burning activities in northern midlatitudes over western and eastern Eurasia. Furthermore, numerical model simulations estimated the year-to-year variation of contribu- tions from anthropogenic sources to be smaller than 30 %– 40 %. These results suggest that the year-to-year variation of biomass burning activities likely affected BC amounts in the Arctic troposphere in spring, at least in the years examined in this study. The year-to-year variations in BC mass con- centrations were also observed at the surface at high Arctic sites Ny-Ålesund and Utqiag ̇vik (formerly known as Barrow, the location of Barrow Atmospheric Baseline Observatory), although their magnitudes were slightly lower than those in COLBC . Numerical model simulations in general successfully re- produced the observed COLBC values for PAMARCMiP and HIPPO3 (within a factor of 2), whereas they markedly un- derestimated the values for ARCTAS-A and NETCARE by factors of 3.7–5.8 and 3.3–5.0, respectively. Because anthro- pogenic contributions account for nearly all of the COLBC (82 %–98 %) in PAMARCMiP and HIPPO3, the good agree- ment between the observations and calculations for these two experiments suggests that anthropogenic contributions were generally well reproduced. However, the significant underes- timations of COLBC for ARCTAS-A and NETCARE suggest that biomass burning contributions were underestimated. In this study, we also investigated plumes with enhanced BC mass concentrations, which were affected by biomass burn- ing emissions, observed at 5 km altitude. Interestingly, the mass-averaged diameter of BC (core) and the shell-to-core diameter ratio of BC-containing particles in the plumes were generally not very different from those in other air samples, which were considered to be mostly aged anthropogenic BC. These observations provide a useful basis to evaluate numer- ical model simulations of the BC radiative effect in the Arctic region in spring.