The height distribution of radio meteors: observations at 2 MHz |
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| Institution: | 1. Nuclear Physics Division, Bhabha Atomic Research Centre, Mumbai 400 085, India;2. Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400 085, India;3. Glass and Advanced Materials Division, Bhabha Atomic Research Centre, Mumbai 400 085, India;4. Homi Bhabha National Institute, Anushaktinagar, Mumbai, 400 094, India;1. National Institute for Space Research (INPE), 12227-010, S. J. Dos Campos, SP, Brazil;2. State Key Laboratory of Space Weather (CBJLSW), Beijing, China;3. Federal Institute of Education, Science and Technology of São Paulo (IFSP), Jacareí, SP, Brazil;4. Salesian University Center of São Paulo (UNISAL), 12600-100, Lorena, SP, Brazil;5. Southern Space Coordination (COESU/INPE/MCTI), Santa Maria, RS, Brazil;1. Department of Meteorology, University of Reading, Reading, UK;2. Department of Electronic and Electrical Engineering, University of Bath, Bath, UK;3. Research Centre for Astronomy and Earth Sciences, GGI, Hungarian Academy of Sciences, Sopron, Hungary;4. Yerevan Physics Institute, Yerevan, Armenia;5. Institute of Atmospheric Physics CAS, Bocni II/1401, 14131 Prague 4, Czech Republic;6. Department of Environmental Engineering, Democritus University of Thrace, Xanthi, Greece;7. Tripura University, Tripura, India;8. Institute of Geophysics, Polish Academy of Sciences, Warsaw, Poland;9. Institute of Applied Physics, Russian Academy of Sciences, Nizhny Novgorod, 603950, Russia;10. School of Chemistry, University of Bristol, Bristol, UK;11. Center for Radio Astronomy and Astrophysics Mackenzie (CRAAM), Engineering School, Presbyterian Mackenzie University, São Paulo, Brazil;12. School of Biological Sciences, University of Bristol, Bristol, UK;13. Renewable Energies Chair and Institute of Earth Sciences, University of Évora, Portugal;14. School of Sustainability, Interdisciplinary Centre Herzliya, Israel;15. Department of Physics, Ariel University, Ariel, Israel;p. Eastern R&D Center, Ariel, Israel;1. Indian Centre for Space Physics, 43 Chalantika, Garia St. Road, Kolkata 700084, India;2. Amity University, Major Arterial Road, Action Area II, Rajarhat, New Town, Kolkata 700135, India;3. Hayakawa Institute of Seismo Electromagnetics Co. Ltd., UEC Alliance Center, 521, 1-1-1 Kojma-cho, Chofu Tokyo 182-0026, Japan;4. Physical Research Laboratory, Navrangpura, Ahmedabad 380 009, India |
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| Abstract: | Conventional meteor radars, operating at wavelengths of around 5–15 m, are unable to detect high-altitude meteors due to the wavelength-dependent echo ceiling. It is suggested that the ‘missing mass’ in the 10−6–10−2 g range of interplanetary material is in fact a high-velocity component which is normally undetected since it ablates at high altitude. This contention is supported by previous work. In this paper we describe measurements of the heights of radio meteors (limiting magnitude about +7) at a wavelength of 150 m (frequency 2 MHz), for which the echo ceiling is above 140 km. The resultant true height distribution is found to peak at ~ 104 km, about 10 km above the peak found by conventional meteor radars. The majority of meteors are detected at or above this peak, and substantial numbers are seen right up to 140 km. It is therefore concluded that the ‘missing mass’, comprising the vast majority of the meteoric input to the atmosphere, ablates well above 100 km. |
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