Single-scattering look-up table for remote sensing and in situ black carbon studies

Coupled atmosphere and ocean remote sensing retrievals of microphysical properties made by the NASA Plankton, Aerosol, Cloud, ocean Ecosystem (PACE) mission require time-consuming single-scattering computations for the constituents. Our line of look-up tables allows us to speed up these computations for aerosols and cloud droplets in the atmosphere, and for coated spheres representing oceanic phytoplankton. In this study, we tabulate the computations of the single-scattering properties of fractal-like aggregates with a complex refractive index of 1.95-i⋅ 0.96, characteristic of bare carbonaceous soot for wavelengths from 0.35 to 2.3 µm. Our new look-up table covers aggregates with fractal dimensions of 1.4-2.8 consisting of 1 to 4,096 touching black carbon monomers with identical radii in the range 0.015 to 0.025 µm. We achieve an increase of at least 10⁶ in computational speed compared to direct calculations. As an application example, we use our look-up table to reproduce the low single-scattering albedo of in situ aerosol measurements acquired during the NASA ACTIVATE mission.