The content and composition of meteoric smoke in mesospheric ice particles from SOFIE observations

This work provides the first observational evidence that ice particles comprising polar mesospheric clouds (PMC) contain small amounts of meteoric smoke (0.01–3% by volume), using measurements from the Solar Occultation For Ice Experiment (SOFIE). PMC observations at wavelengths from the ultraviolet through the infrared are inconsistent with pure ice, but can be explained in terms of the extinction simulated for a mixture of ice and meteoric smoke. Simulations of ice–smoke mixtures considered 25 different smoke compositions. The PMC observations were consistent with smoke composed of carbon (C), wüstite (FeO), or magnesiowüstite (MgxFe1−xO, x=0.1–0.6), and inconsistent with the other compositions. A method was established for simultaneously retrieving PMC particle size and the volume fraction of smoke in ice using SOFIE observations at multiple wavelengths. Compared to assuming pure ice, SOFIE retrievals considering ice–smoke mixtures yield smaller ice radii (24%) and higher concentrations (137%).