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Abstract:
We present mass spectroscopic in situ data from rocket flights of two improved ion mass spectrome- ters in the mesosphere and lower thermosphere region. The instruments were optimized to detect large ions with a mass-to-charge ratio (m/z, mass) of up to m/z 2000 and 20 000 respectively, for analysis of meteor smoke par- ticles. The flights were performed in the framework of the polar mesospheric winter echo (PMWE) campaigns, initiated and coordinated by the Leibniz Institute of Atmospheric Physics (IAP), to investigate polar mesospheric winter radar echoes in Andøya (Norway) in 2018 and 2021. Both flights were successful and allowed the mass number and chemical composition of charged meteor smoke particles to be investigated. We found a complex and diverse composition of positively and negatively charged molecules and particles within our mass range in a region that is notoriously difficult to get mass spectroscopic data from. While at altitudes below 85 km we ob- served negatively charged particles of up to several thousands of atomic mass units, above this altitude we found possible building blocks of these large particles that form right after their ablation from the parent meteorite material. In the first flight we detected no positively charged particles above m/z 100 and a difficult-to-interpret signal for negatively charged particles beyond our mass range of m/z 2000. In the second flight, however, we detected positively charged particles between around m/z 180 and 350 and a number of different negatively charged particles up to m/z 5500. Due to the very large mass range of m/z 20 000 used in the second flight and the subsequent lower mass resolution, unambiguous mass identification is not possible. A particular interesting pattern was found at 80.8 km of a compound that seems to double its mass around m/z 225, 450, 900 and 1800.
Comparing our findings to proposed meteor smoke particle compounds by other authors, our observations would be consistent with magnetite, fayalite and forsterite. However, other possible compounds cannot be ex- cluded.
