L. Liu et al. demonstrated how strongly long-range transport shapes submicron aerosol composition in Jülich, Germany. Back-trajectory analysis showed that distinct air mass origins coincided with distinct PMF-resolved source contributions: spring air masses influenced by wildfires were characterized by enhanced biomass-burning organic aerosol (BBOA), while marine-influenced periods were associated with a clearly resolved MSA-rich organic aerosol factor. These results illustrate how emissions transported over hundreds to thousands of kilometers can substantially alter regional aerosol composition.
Crucially, PMF in SoFi demonstrates a clear advantage over traditional single-tracer approaches for identifying regional transport. By analyzing the full mass spectral signature of transported plumes within SoFi, PMF yields source factors that align consistently with air mass history and avoids false transport signals that can occur with tracer-based methods, especially in complex atmospheric conditions. This provides a clearer and more reliable picture of how regional transport shapes seasonal aerosol variability.