Spectral discrimination of coarse and fine mode optical depth

The recognition that the aerosol particle size distribution (PSD) is effectively bimodal permits the extraction of the fine and coarse mode optical depths (τ f and τ c ) from the spectral shape of the total aerosol optical depth (τ a = τ f + τ c ). This purely optical technique avoids intermediate computations of the PSD and yields a direct optical output that is commensurate in complexity with the spectral information content of τ a . The separation into τ f and τ c is a robust process and yields aerosol optical statistics, which are more intrinsic than those, obtained from a generic analysis of τ a . Partial (optical) validation is provided by (1) demonstrating the physical coherence of the simple model…