Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
1778134 | Journal of Atmospheric and Solar-Terrestrial Physics | 2007 | 20 Pages |
Abstract
In this study, we present multi-instrument observations of a strong positive phase of ionospheric storm, which occurred on September 10, 2005 during a moderate geomagnetic storm with minimum Dst=â60 nT and maximum Kp=6-. The daytime electron density measured by the Millstone Hill incoherent scatter radar (42.6°N, 288.5°E) increased after 13 UT (â¼8 LT) compared with that before the storm. This increase is observed throughout the daytime, lasts for about 9 h, and covers F-region altitudes above â¼230 km. At the altitude of 300 km, the maximum increase in Ne reaches a factor of 3 by 19:30-20:00 UT and is accompanied by a â¼1000 K decrease in electron temperature, a â¼100-150 K increase in ion temperature, and a strong upward drift. Observations by Arecibo ISR (18.3°N, 293.3°E) reveal similar features, with the maximum increase in electron density reaching a factor of 2.5 at 21:30 UT, i.e. 1.5-2 h later than over Millstone Hill. The GPS TEC data show that the increase in electron density observed at Millstone Hill and Arecibo is only a part of a global picture reflected in TEC. The increase in TEC reaches a factor of 2 and covers middle and low latitudes at 19 UT. At later times this increase moves to lower latitudes. A combination of mechanisms were involved in generation of positive phase. The penetration electric field resulted in Ne enhancements at subauroral and middle latitudes, the TAD/TID played an important role at middle and lower latitudes, and increase in O/N2 ratio could contribute to the observed positive phase at middle and lower latitudes. The results show the importance of an upward vertical drift at â¼140-250 km altitude, which is observed for sustained period of time and assists in the convergence of ionization into the F-region.
Keywords
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Physical Sciences and Engineering
Earth and Planetary Sciences
Geophysics
Authors
L.P. Goncharenko, J.C. Foster, A.J. Coster, C. Huang, N. Aponte, L.J. Paxton,