Assessing Atmospheric Aerosol Transport and Transformation in Central Europe: Insights from Project Trace

SHUBHI ARORA, Laurent Poulain, Radek Lhotka, Jakub Ondráček, Petra Pokorná, Petr Vodicka, Jaroslav Schwarz, Vladimír Ždímal, Hartmut Herrmann, Leibniz Institute of Tropospheric Research

     Abstract Number: 134
     Working Group: Aerosol Chemistry

Abstract
The trend in PM10 concentrations in Europe has stagnated over the last two decades, despite ongoing reductions in PM emissions, possibly due to the aging processes of atmospheric particles and their long-range transport. Project TRACE aims to assess these factors in Central Europe, focusing on anthropogenic sources such as coal and wood combustion. Using synergic online (Aerosol Mass Spectrometer and Aethalometer) and offline (GC-MS and Ion Chromatography) methods, the project evaluated the transport and transformation of atmospheric aerosols. In 2021, measurements were conducted at three sites (Melpitz, DE; Kosetice, CZ; and Frydlant, CZ) during winter (February 1st – March 10th) and summer (July 1st – August 20th). During winter, inorganic species (nitrate and sulfate) dominated aerosol particles at all sites, while organics became dominant in summer. At Melpitz, winter nitrate and sulfate concentrations were higher (24 µg/m³ and 9 µg/m³ respectively) compared to summer (9 µg/m³ and 5 µg/m³). Significant seasonal differences were observed not only in mass concentrations but also in the babs coefficient for brown carbon absorption and its relative contribution to total absorption at 370 nm. Winter brown carbon absorption coefficients varied across stations: 11.87 Mm^-1 for Frydlant, 9.07 Mm^-1 for Melpitz, and 8.77 Mm^-1 for Kosetice, with a coefficient of variation of 14.09%. This could be an indication to the distinct character of the type and source of brown carbon at Frydlant which according to our study is purportedly darker (more absorbing) than that observed at Kosetice, albeit its low contribution. Meteorological conditions and back air mass trajectories (96 hrs, 500 m above ground altitude) based on the NOAA-HYSPLIT model were also used to identify potential connections between sites and the geographical origin of emissions.