Long-term trends of black carbon and particle number concentration in the lower free troposphere in Central Europe

Environmental Sciences Europe

Gabriele Frank¹  Martine Collaud Coen²  Ralf Sohmer³  Cedric Couret³  Ludwig Ries³  Martin Gysel-Beer⁴  Benjamin Tobias Brem⁴  Leizel Madueño⁵  Alfred Wiedensohler⁵  Thomas Tuch⁵  Kay Weinhold⁵  Markus Hermann⁵  Jia Sun⁵  Laurent Poulain⁵  Wolfram Birmili⁶  Nan Ma⁷  Ye Yuan⁸ 

[1] Deutscher Wetterdienst (DWD), Offenbach, Germany;Federal Office of Meteorology and Climatology, MeteoSwiss, Payerne, Switzerland;German Environment Agency (UBA), Zugspitze, Germany;Laboratory of Atmospheric Chemistry, Paul Scherrer Institute, Villigen PSI, Switzerland;Leibniz Institute for Tropospheric Research (TROPOS), Leipzig, Germany;Leibniz Institute for Tropospheric Research (TROPOS), Leipzig, Germany;German Environment Agency (UBA), Dessau-Roßlau, Germany;Leibniz Institute for Tropospheric Research (TROPOS), Leipzig, Germany;Institute for Environmental and Climate Research, Jinan University, Guangzhou, China;TUM School of Life Sciences, Technical University of Munich (TUM), Freising, Germany;

关键词: Black carbon;    Particle number concentration;    Long-term trend;    Free troposphere;   

DOI  :  10.1186/s12302-021-00488-w

来源: Springer

【 摘 要 】

BackgroundThe implementation of emission mitigation policies in Europe over the last two decades has generally improved the air quality, which resulted in lower aerosol particle mass, particle number, and black carbon mass concentration. However, little is known whether the decreasing particle concentrations at a lower-altitude level can be observed in the free troposphere (FT), an important layer of the atmosphere, where aerosol particles have a longer lifetime and may affect climate dynamics. In this study, we used data from two high-Alpine observatories, Zugspitze-Schneefernerhaus (ZSF) and Jungfraujoch (JFJ), to assess the long-term trends on size-resolved particle number concentrations (PNCs) and equivalent black carbon (eBC) mass concentration separated for undisturbed lower FT conditions and under the influence of air from the planetary boundary layer (PBL) from 2009 to 2018.ResultsThe FT and PBL-influenced conditions were segregated for both sites. We found that the FT conditions in cold months were more prevalent than in warm months, while the measured aerosol parameters showed different seasonal patterns for the FT and PBL-influenced conditions. The pollutants in the PBL-influenced condition have a higher chance to be transported to high-altitudes due to the mountainous topography, leading to a higher concentration and more distinct seasonal variation, and vice versa. The long-term trends of the measured aerosol parameters were evaluated and the decreased aerosol concentrations were observed for both FT and PBL-influenced conditions. The observed decreasing trends in eBC concentration in the PBL-influenced condition are well consistent with the reported trends in total BC emission in Germany and Switzerland. The decreased concentrations in the FT condition suggest that the background aerosol concentration in the lower FT over Central Europe has correspondingly decreased. The change of back trajectories in the FT condition at ZSF and JFJ was further evaluated to investigate the other possible drivers for the decreasing trends.ConclusionsThe background aerosol concentration in the lower FT over Central Europe has significantly decreased during 2009–2018. The implementation of emission mitigation policies is the most decisive factor and the decrease of the regional airmass occurrence over Central Europe also has contributed to the decreasing trends.

【 授权许可】

CC BY