Studies of SLCPs, greenhouse gases, and their interaction with the terrestrial ecosystem during the ArCS project

Abstract Black carbon (BC) aerosols and methane are considered as a part of short-lived climate pollutants (SLCPs), and the uncertainty of the emission, removal processes, and its impact on global change is quite large. This paper reviews studies of SLCPs and CO2 performed during the Arctic Challenge for Sustainability (ArCS) project focusing on the Asian influx into the Arctic. For a more detailed understanding of the characteristics of BC particles, ground-based continuous observation for BC has been newly started at two sites in the Arctic region. An accurate BC observation was also repeatedly conducted on R/V Mirai until 2019. At the cruise in 2014, we found that a notable fraction (~20%) of the rBC particles had a “noncore/nonshell structure,” meaning that there was rBC located on/near the surface of the particles. Continuous measurement of the terrestrial ecosystem and CO2 concentration was also carried out at the Poker Flat in Alaska. By using data at PFRR, the data of the year 2013 (with an unusually dry summer) implied the possible response of the terrestrial ecosystem to global warming. We have also developed forward and backward models to estimate the source-receptor relationship, even for the species which is affected by the wet deposition processes, and 60% of BC deposition on the sampling date was estimated to be transported from China.