Multi-Instrumental Observations of Nonunderdense Meteor Trails
Using data from the Sodankylä Geophysical Observatory (67°22′N, 26°38′E, Finland) meteor camera from the whole year 2015, we identified and investigated 28 optical meteors with accompanying ionization trails unambiguously detected by the Sodankylä Geophysical Observatory ionosonde, which sounded the...
| Published in: | Journal of Geophysical Research: Space Physics |
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| Main Authors: | , , , , |
| Format: | Article in Journal/Newspaper |
| Language: | English |
| Published: |
American Geophysical Union (AGU), Wiley
2019
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| Subjects: | |
| Online Access: | https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2018JA025405 http://hdl.handle.net/2381/45268 https://doi.org/10.1029/2018JA025405 |
| Summary: | Using data from the Sodankylä Geophysical Observatory (67°22′N, 26°38′E, Finland) meteor camera from the whole year 2015, we identified and investigated 28 optical meteors with accompanying ionization trails unambiguously detected by the Sodankylä Geophysical Observatory ionosonde, which sounded the ionosphere once per minute with frequency rising from 0.5 to 16 MHz. These ionosonde reflections were obtained from heights around 90 km. The electron line densities of the trails were found to be between 10^14 and 10^16 m^−1, which characterize the trails as nonunderdense (i.e., transitional and overdense). The ionosonde reflections were observed for a few minutes, with decreasing maximal frequency of the return. During the first 250 s, for the trails with initial line density about (2–3) · 10^15 m^−1 the return frequency decreased with time corresponding to the diffusional expansion of cylindrical meteor trails, that is, f ∝ t^−γ, where the exponent γ = 0.5, whereas less dense trails decayed slower (γ ≈ 0.2) and more dense trails decayed faster (γ ≈ 1). In many cases the meteor events were accompanied by nonspecular long‐lived detections using a colocated all‐sky interferometric meteor radar with operating frequency 36.9 MHz. As a rule the meteor radar echo durations were longer than expected from diffusional expansion of cylindrical meteor trails and their amplitudes were highly variable. We suggest that the slower frequency decrease of the ionosonde echoes and the nonspecular long‐lived meteor radar echoes might be associated with the presence of meteoric dust. Data used in the paper are given in Tables 1 and 2 and presented in figures. The data of the meteor camera, ionosonde, and meteor radar were collected at SGO (http://www.sgo.fi/). We thank Eric Stempels for developing the meteor camera software. S. S. acknowledges support from the Academy of Finland via grant 310348. J. K. acknowledges support from the Swedish Research Council via project grant 2012‐4074. The authors acknowledge the support by the International Space Science Institute (ISSI) and discussions within the ISSI Team 410 on New Features in the Meteor Radar Observations and Applications for Space Research. Peer-reviewed Publisher Version |
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