The spacecraft continues to perform nominally.
AIM/SOFIE observations were recently used to determine the chemical composition of meteoric smoke particles in the mesosphere, and to estimate the meteoric influx into Earth’s atmosphere [Hervig et al., 2017]. The composition of smoke particles was determined by comparing SOFIE measurements at multiple wavelengths to model simulations for a variety of compounds. An example of the results is shown in the figure below, where SOFIE extinction ratios (colored regions) are compared to model results for various smoke compositions (diamonds, only some are labeled for clarity). The SOFIE – model comparisons show that smoke consists of particles made of magnesium, iron, and silica (e.g., magnesiowüstite (Mg0.2Fe0.8O), magnetite (Fe3O4), or olivine (Mg0.8Fe1.2SiO4)). This is important knowledge, because chemical reactions and cloud processes in the middle atmosphere can change depending on what kind of smoke particles are present. The second part of the investigation was to determine the meteoric influx into Earth’s atmosphere, which was possible by comparing SOFIE with models. The results indicate that the ablated meteoric influx is 3.3 metric tons per day (t/d). With new knowledge of the smoke composition it was possible to further deduce that 55% of this is iron and ~15% is magnesium. The SOFIE result implies a total meteoric influx (ablated material plus the material that does not burn up) of 30 t/d, when considering a recent description of the speciation of meteoric material. This is important because the previous influx estimates cover a huge range, 5 to 270 t/d. We need a better estimate because meteoric influx has implications for transport in the upper atmosphere, and dust production in our solar system. Additionally, the amount of dust entering our atmosphere has implications for noctilucent clouds, ozone chemistry in the stratosphere, and ocean productivity.
Hervig, M. E., Brooke, J. S. A., Feng, W., Bardeen, C. G., Plane, J. M. C. (2017), Constraints on meteoric smoke composition and meteoric influx using SOFIE observations with models, J. Geophys. Res. Atmospheres, 122, doi:10.1002/2017JD027657. (article)