Comparison of ionospheric electrical conductances inferred from coincident radar and spacecraft measurements and photoionization models |
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| Institution: | 1. Geoscience and Engineering Center, SRI International, Menlo Park, California, U.S.A.;2. Phillips Laboratory (AFSC), Hanscom AFB, MA 01731, U.S.A.;1. NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA;2. Johns Hopkins University Applied Physics Laboratory, Laurel, MD, USA;3. Laboratoire d’astrophysique de Bordeaux, Univ. Bordeaux, CNRS, Pessac, France;4. National Space Science Center, China;5. National Institute for Space Research, São José dos Campos, Brazil;6. Instituto de Astronomía y Física del Espacio, IAFE, UBA-CONICET, C.A.B.A., 1428, Argentina;7. Physical Research Laboratory, Ahmedabad 380009, India;8. Inter-University Centre for Astronomy and Astrophysics, Post Bag 4, Ganeshkhind, Pune 411007, India;9. University of Calgary, Alberta, Canada;10. Los Alamos National Laboratory, Los Alamos, NM, USA;11. Department of Physics, National and Kapodistrian University of Athens, Athens, Greece;12. Department of Mathematics, Physics and Electrical Engineering, Northumbria University, Newcastle, UK;13. Swiss Federal Institute of Technology, Zürich, Switzerland;14. Department of Meteorology, University of Reading, Earley Gate, PO Box 243, Reading RG6 6BB, UK;15. ESTEC, European Space Agency, Noordwijk, the Nethelands;p. Space Research Institute, Austrian Academy of Sciences, Graz 8042, Austria;q. LESIA, Observatoire de Paris, Université PSL, CNRS, Sorbonne Université, Université Paris Cité, 5 place Jules Janssen, 92195 Meudon, France;r. Department of Physics, University of Helsinki, Helsinki, Finland;s. Instituto de Geofísica, Universidad Nacional Autónoma de México, Ciudad Universitaria, Coyoacán, C.P. 04510 Mexico City, Mexico;t. Institute of Space and Astronautical Science/Japan Aerospace Exploration Agency, Sagamihara, Japan;u. Space Research Institute, Moscow, Russia;v. Korea Astronomy and Space Science Institute, Daejeon, South Korea;w. Hellenic Space Center, Athens, Greece;x. Space and Earth Observation Centre, Finnish Meteorological Institute, Helsinki, Finland;1. Department of Conservative Dentistry, School of Dentistry, Kyungpook National University, Daegu, Korea;2. Department of Conservative Dentistry, School of Dentistry, Dental Research Institute, Pusan National University, Yangsan, Korea;3. Department of Endodontics, New York University College of Dentistry, New York, New York;1. Planetary Science Division, Physical Research Laboratory, Ahmedabad, India;2. Faculty of Science, Pacific Academy of Higher Education and Research, University, Udaipur, India;1. Bichat Claude Bernard Hospital-Paris VII University, Paris, France;2. Quebec Heart & Lung Institute, Laval University, Quebec City, Quebec, Canada |
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| Abstract: | Height-integrated electrical conductivities (conductances) inferred from coincident Sondrestrom incoherent scatter radar and DMSP-F7 observations in the high-latitude ionosphere during solar minimum are compared with results from photoionization models. We use radar and spacecraft measurements in combination with atmospheric and ionospheric models to distinguish between the contributions of the two main sources of ionization of the thermosphere, namely, solar UV/EUV radiation and auroral electron precipitation. The model of Robinsonet al. (1987, J. geophys. Res.89, 3951) of Pedersen and Hall conductances resulting from electron precipitation appears to be in accordance with radar measurements. Published models of the conductances resulting from photoionization that use the solar zenith angle and the solar 10.7-cm radio flux as scaling parameters are, however, in discrepancy with radar observations. At solar zenith angles of less than 90°, the solar radiation components of the Pedersen and Hall conductances are systematically overestimated by most of these models. Geophysical conditions that have some bearing on the state of the high-latitude thermosphere (e.g. geomagnetic and substorm activity and a seasonal variation of the neutral gas distribution) seem to influence the conductivity distribution but are to our knowledge not yet sufficiently well modelled. |
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