Non-negative Matrix Factorization source apportionment and transboundary transport of PM2.5 across the Czech Republic, 2021-2025

NMF source apportionment: input concentration dataset Single sheet, 4384 rows x 57 columns. Each row is one 24-h (or campaign-specific) filter sample from one of 33 air-quality monitoring sites acrossthe Czech Republic, collected during heterogeneous annual monitoringcampaigns run in 2021-2025 (see Table S1 of the manuscript for theper-site sampling schedule).