High-time resolution PM source apportionment assisted by spectrum-based characteristics analysis.

Characteristics extraction and anomaly analysis based on frequency spectrum can provide crucial support for source apportionment of PM pollution. In this study, an effective source apportionment framework combining the Fast Fourier Transform (FFT)- and Continuous Wavelet Transform (CWT)-based spectral analyses and Positive Matrix Factorization (PMF) receptor model is developed for spectrum characteristics extraction and source contribution assessment. The developed framework is applied to Beijing during the winter heating period with 1-h time resolution.