Comparison of the Hill–Siscoe polar cap potential theory with the Weimer and AMIE models |
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| Authors: | Michael C Kelley Geoffrey Crowley Daniel R Weimer |
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| Institution: | 1. School of Electrical and Computer Engineering, Cornell University, Ithaca, NY 14853, USA;2. Atmospheric & Space Technology Research Associates (ASTRA), LLC, San Antonio, TX, USA;3. Bradley Department of Electrical and Computer Engineering, Virginia Tech., Blacksburg, VA, USA;1. Institute of Space Sciences, National Central University, Chung-Li 32054, Taiwan;2. Indian Institute of Geomagnetism, Mumbai, India;3. Applied Mathematics, University of Sheffield, Sheffield, UK;1. Department of Physics, University of Lagos, Akoka, Yaba, Lagos, Nigeria;2. National Space Research and Development Agency, Abuja, Nigeria;3. Department of Physics, Federal University of Technology, Akure, Nigeria;4. Department of Physics, Lagos State University, Ojo, Lagos, Nigeria;1. Department of Physics, Manav Rachna University, Faridabad 121001, India;2. Indian Institute of Geomagnetism, Mumbai 410206, India;1. Institute of Radio Physics and Electronics, University of Calcutta, 92 Acharya Prafulla Chandra Road, Kolkata 700009, India;2. The Abdus Salam International Centre for Theoretical Physics (ICTP), Trieste, Italy;3. Institute of Radio Astronomy, National Academy of Sciences of Ukraine (IRA NASU), Kharkiv, Ukraine;4. Department of Physics of the Earth, Astronomy and Astrophysics I, Facultad de Ciencias Físicas, University Complutense of Madrid (UCM), Ciudad Universitaria, Plaza de Ciencias 1, 28040 Madrid, Spain;5. Dept. of Applied Physics, S V National Institute of Technology, Surat 395007, India;6. Department of Electrical Engineering, University of Brasilia (UnB), 70910-900 Brasília, DF, Brazil;7. Smt. Kasturbai Walchand College, Sangli, India;8. Laboratoire de Physique de l''Atmosphère, Université Felix Houphouet Boigny, 22 BP 582 Abidjan 22, Cote d’Ivoire;9. T/ICT4D Laboratory, International Center for Theoretical Physics, Strada Costiera 11, 34014 Trieste, Italy;1. Institute of Earthquake Science, CEA, 100036 Beijing, China;2. Institute of Crustal Dynamics, CEA, 100085 Beijing, China;1. Central Aerological Observatory, Pervomayskaya Str., 3, 141700 Dolgoprudny, Russia;2. Fusion Numerics International LLC, 373 Arapahoe Ave, Boulder, CO 80302, USA |
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| Abstract: | The magnetic storm on November 2004 was characterized by a high solar wind pressure and thus offers a unique opportunity to test the Hill–Siscoe formula (H–S) for the polar cap potential (PCP). To estimate the polar cap potential, we use the Weimer Statistical Convection Model (WCM), and the Assimilative Mapping of Ionospheric Electrodynamics Model (AMIE), based on ingestion of a number of data sets. H–S is in excellent agreement with WCM, and with AMIE during times when DMSP is used in the latter. The implication is that the AMIE conductivity model yields conductivities that are too high by a factor of 2–3. Both H–S and WCM display saturation effects, although WCM is more severe. The two methods track well until an IEF of about 20 mV/m occurs, where H–S continues to increase while WCM levels off. Even at high electric field values, the pressure increases the denominator of the H–S formula by 60%, keeping the potential lower than its saturation value. There are several H–S points above 250 kV, even up to 400 kV, that are not found in WCM and occur right after a rapid transition from Bz north to south. For Bz north, we find evidence for a saturation effect on the PCP at large IEF, little effect as a function of solar wind velocity, and an increase of the PCP with increasing pressure. This seems to rule out viscous interaction but may involve geometric changes in the high-altitude polar cusp that affect recombination there for Bz north. |
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