Daytime Vertical E×B Drift Velocities Inferred from Ground-Based Equatorial Magnetometer Observations
The daytime equatorial electrojet is a narrow band of enhanced eastward current flowing in the 100–120 km altitude region within ±2° latitude of the dip equator. A unique way of determining the daytime strength of the electrojet is to observe the difference in the magnitudes of the Horizontal (H) component between a magnetometer placed directly on the magnetic equator and one displaced 6–9° away. The difference between these measured H values provides a direct measure of the daytime electrojet current, and in turn, the magnitude of the vertical E×B drift velocity in the F region ionosphere. This paper emphasizes two major topics related to the title: (1) Describes and summarizes the techniques developed for obtaining the daytime, E×B drift velocities from ground-based magnetometer observations, and (2) Describes and summarizes the equatorial, ionospheric physical transport mechanisms that have been addressed using these techniques.
KeywordsTotal Electron Content Drift Velocity Magnetic Equator Equatorial Electrojet Incoherent Scatter Radar
We thank Dr. Koki Chau, Director of the Jicamarca Radio Observatory, for providing the Jicamarca and Piura magnetometer data. The Jicamarca Radio Observatory is a facility of the Instituto Geofisico del Peru, Ministry of Education, and is operated with support from the NSF Cooperative agreement ATM-o432565. We also thank Prof. Kiyo Yumoto, Dept. of Earth and Planetary Sciences, Kyushu University, Fukuoka, Japan for supplying the Davao and Muntinlupa magnetometer observations.
- Anderson D, Araujo-Pradere EA, Scherliess L (2009) Comparing daytime, equatorial E×B drift velocities and TOPEX/TEC observations associated with the 4-cell, non-migrating tidal structure. Ann Geophys 7:1–7Google Scholar
- Anderson DN, Klobuchar JA, Doherty PH, Rastogi RG (1992) A comparison of theoretical modeling of the low latitude ionosphere against TEC data from the indian longitudes during solar minimum. Int Beacon Symposium, MIT, Boston, MAGoogle Scholar
- Chau JL (1998) Examination of various techniques for measuring wind velocities using clear-air radars, with emphasis on vertical wind measurements. Ph.D Thesis, University of Colorado at BoulderGoogle Scholar
- Hanson WB, Moffett RJ (1966) Ionization transport effects in the equatorial F region. J Geophys Res 71:5559–5572Google Scholar
- Maruyama N, Sazykin S, Spiro R, Andearson D, Anghel A, Wolf RA, Toffoletto FR, Fuller-Rowell TJ, Codrescu MV, Richmond AD, Millward G (2007) Modeling storm-time electrodynamics of the low-latitude ionosphere-thermosphere system: can long lasting disturbance electric fields be accounted for? J Atmos Solar-Terr Phys 69:1182–1199CrossRefGoogle Scholar
- Wang W, Lei J, Burns AG, Wiltberger M, Richmond AD, Solomon SC, Killeen TL, Talaat ER, Anderson DN (2008) Ionospheric electric field variations during a geomagnetic storm simulated by a coupled magnetosphere ionosphere thermosphere (CMIT) model. Geophys Res Lett 15:L18105. http://doi:10.1029/2008GL035155 CrossRefGoogle Scholar
- Woodman RF, Villanueva F (1995) Comparisons of electric fields measured at F-region heights with 150 km – irregularity drift measurements. Paper presented at the 9th international symposium on equatorial aeronomy, Bali, IndonesiaGoogle Scholar