Magnetic storm effects on the variation of TEC over Ilorin an equatorial station

J. O. Adeniyi; P. H. Doherty; O. A. Oladipo; O. Bolaji

doi:10.1002/2014rs005404

Magnetic storm effects on the morphology of the equatorial F2-layer

Journal of Atmospheric and Terrestrial Physics ◽

10.1016/0021-9169(86)90019-x ◽

1986 ◽

Vol 48 (8) ◽

pp. 695-702 ◽

Cited By ~ 41

Author(s):

J.O Adeniyi

Keyword(s):

Magnetic Storm ◽

Storm Effects

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Space weather impact on the equatorial and low latitude F-region ionosphere over India

Annales Geophysicae ◽

10.5194/angeo-24-97-2006 ◽

2006 ◽

Vol 24 (1) ◽

pp. 97-105 ◽

Cited By ~ 20

Author(s):

R. S. Dabas ◽

R. M. Das ◽

V. K. Vohra ◽

C. V. Devasia

Keyword(s):

Magnetic Storm ◽

Electric Fields ◽

Space Weather ◽

Recovery Phase ◽

Equatorial Region ◽

Storm Events ◽

Low Latitude ◽

Equatorial Station ◽

Weather Impact ◽

F Region

Abstract. For a detailed study of the space weather impact on the equatorial and low latitude F-region, the ionospheric response features are analysed during the periods of three recent and most severe magnetic storm events of the present solar cycle which occurred in October and November 2003, and November 2004. The F-layer base height (h'F), peak height (hmF2) and critical frequency (foF2) data, from Trivandrum, an equatorial station and Delhi, a low latitude location, are examined during the three magnetic storm periods. The results of the analysis clearly shows that the height of the F-region (both h'F and hmF2), at the equator and low latitude, simultaneously increases by 200 to 300 km, in association with maximum negative excursion of Dst values around the midnight hours with a large depletion of ionization over the equator, which is followed by an ionization enhancement at low latitude during the recovery phase of the storm. At Delhi, fast variations up to 200 m/s are also observed in the F-layer vertical upward/downward velocity, calculated using Doppler shifts, associated with the maximum negative excursion of Dst. This shows that during magnetic disturbances, the equatorial ionization anomaly (EIA) expands to a much wider latitude than the normal fountain driven by the E/F-layer dynamo electric fields. It is also observed that during the main phase of the storm, at low latitude there is generally an enhancement of F-region ionization with an increase in h'F/hmF2 but in the equatorial region, the ionization collapses with a decrease in h'F/hmF2, especially after sunset hours. In addition, at the equator the normal pre-sunset hours' enhancement in h'F is considerably suppressed during storm periods. This might be due to changes in magnitude and direction of the zonal electric field affecting the upward E×B drift and hence the plasma distribution in the form of a decrease in electron density in the equatorial region and an increase in the low latitude region. In association with disturbance electric fields, the enhanced storm-induced equatorward meridional winds in the thermosphere can also further amplify the F-layer height rise at low latitudes during the post-midnight hours, as observed in two of the storm periods.

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Positive storm effects in the dayside polar ionospheric F-region observed by EISCAT and ESR during the magnetic storm of 15 May 1997

Annales Geophysicae ◽

10.5194/angeo-20-1377-2002 ◽

2002 ◽

Vol 20 (9) ◽

pp. 1377-1384 ◽

Cited By ~ 9

Author(s):

S. Y. Ma ◽

H. T. Cai ◽

H. X. Liu ◽

K. Schlegel ◽

G. Lu

Keyword(s):

Electron Temperature ◽

Magnetic Storm ◽

Radar Data ◽

Auroral Oval ◽

Soft Particle ◽

Plasma Convection ◽

Particle Precipitation ◽

Storm Effects ◽

Cusp Region ◽

F Region

Abstract. EISCAT/ESR radar data and in situ FAST and POLAR satellite observations are coordinately analyzed to investigate positive ionospheric storm effects in the dayside upper F-region in both the polar cap and the auroral oval during the magnetic storm of 15 May 1997. An ionization enhancement, lasting for about 2.5 h, appeared first over the EISCAT site around magnetic noon; about one hour later, a similar ionization enhancement was also seen over ESR. During the concerned time period ion energy spectra measured on board FAST show clearly continuous energy-latitude dispersion when the satellite passed by over the EISCAT latitude. This implies that EISCAT was located under the polar cusp region which was highly active, and expanded greatly equatorwards due to magnetopause reconnections during long-lasting southward IMF. Simultaneously, soft particles of the magnetosheath precipitated into the F-region ionosphere and caused the positive storm effects over EISCAT. The coincident increase in electron temperature at EISCAT gives additional evidence for soft particle precipitation. Consistently, POLAR UV images show strong dayside aurora extending to as low as 62° N magnetic latitude. The ionization enhancement over ESR, however, seems not to be caused by local particle precipitation, evidenced by a lack of enhanced electron temperature. The observed plasma convection velocity and data-fitted convection patterns by AMIE suggested that it is likely to be a polar patch originating from the cusp region and traveling to the ESR site.Key words. Ionosphere (auroral ionosphere; particle percipitation) Magnetospheric physics (storms and substorms)

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