Is the near-spherical shape the “new black” for smoke?

Kurzfassung

We examine the capability of near-spherical-shaped particles to reproduce the non-typical Particle Linear Depolarization Ratio (PLDR) values measured over Europe for stratospheric smoke originating from Canadian wildfires. The smoke layers were detected both in the troposphere and the stratosphere, though in the latter case the particles presented PLDR values of almost 18 % at 532 nm as well as a strong spectral dependence from the UV to the Near-IR. The assumption that the smoke particles have a near-spherical shape allows for the reproduction of the observed PLDR and Lidar Ratio (LR), whereas this was not possible when using more complicated shapes. The results presented here are supported by recent findings in the literature, showing that up to now the near-spherical shape (or closely similar shapes) is the only morphology found capable of reproducing the observed intensive optical properties of stratospheric smoke, as well as their spectral dependence.