Abstract
Long-term assessment of severe wildfires and associated air pollution and related climate patterns in and around the Arctic is essential for assessing healthy human life status. To examine the relationships, we analyzed the National Aeronautics and Space Administration (NASA) modern-era retrospective analysis for research and applications, version 2 (MERRA-2). Our investigation based on this state-of-the-art atmospheric reanalysis data reveals that 13 out of the 20 months with the highest PM2.5 (corresponding to the highly elevated organic carbon in the particulate organic matter [POM] form) monthly mean mass concentration over the Arctic for 2003–2017 were all in summer (July and August), during which POM of 0.5 μg m−3 and PM2.5 were positively correlated. This correlation suggests that high PM2.5 in the Arctic is linked to large wildfire contributions and characterized by significant anticyclonic anomalies (i.e. clockwise atmospheric circulation) with anomalous surface warmth and drier conditions over Siberia and subpolar North America, in addition to Europe. A similar climate pattern was also identified through an independent regression analysis for the July and August mean data between the same atmospheric variables and the sign-reversed Scandinavian pattern index. We named this pattern of recent atmospheric circulation anomalies the circum-Arctic wave (CAW) pattern as a manifestation of eastward group-velocity propagation of stationary Rossby waves (i.e. large-scale atmospheric waves). The CAW induces concomitant development of warm anticyclonic anomalies over Europe, Siberia, Alaska, and Canada, as observed in late June 2019. Surprisingly, the extended regression analysis of the 1980–2017 period revealed that the CAW pattern was not prominent before 2003. Understanding the CAW pattern under future climate change and global warming would lead to better prediction of co-occurrences of European heatwaves and large-scale wildfires with air pollution over Siberia, Alaska, and Canada in and around the Arctic in summer.
Highlights
Global concern over wildfires has increased under the ongoing global warming (e.g. Running 2006, Jolly et al 2015, Veira et al 2016)
A number of questions remained unanswered. To address this knowledge gap, we focused on three key factors in this study: (a) statistical relationships among wildfires, PM2.5, and wildfire-related aerosols, especially under high air pollution (i.e. PM2.5) conditions, (b) identifying the dominant climate pattern under high PM2.5 conditions in the Arctic, and (c) identifying whether this pattern has occurred only in recent years
Characteristics of PM2.5 and aerosols, and their relationships with wildfire Here, we investigate monthly PM2.5 variations during 2003–2017 by selecting 20 months with the worst air quality in the Arctic region
Summary
Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Teppei J Yasunari1,2,3,∗ , Hisashi Nakamura4 , Kyu-Myong Kim5 , Nakbin Choi6 , Myong-In Lee6 , Yoshihiro Tachibana7 and Arlindo M da Silva5 Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. Keywords: wildfire, aerosol, PM2.5, summer, Arctic, climate pattern, atmospheric circulation Supplementary material for this article is available online
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
