scholarly journals Response of the equatorial and low-latitude ionosphere in the Indian sector to the geomagnetic storms of January 2005

2009 ◽  
Vol 114 (A6) ◽  
pp. n/a-n/a ◽  
Author(s):  
V. Sreeja ◽  
C. V. Devasia ◽  
Sudha Ravindran ◽  
Tarun Kumar Pant ◽  
R. Sridharan
Keyword(s):  
Geomagnetic Storms ◽  
Low Latitude ◽  
Low Latitude Ionosphere ◽  
Indian Sector

scholarly journals Changes in the longitudinal structure of the low-latitude ionosphere during the July 2004 sequence of geomagnetic storms

2008 ◽  
Vol 113 (A11) ◽  
pp. n/a-n/a ◽  
Author(s):  
N. M. Pedatella ◽  
J. M. Forbes ◽  
J. Lei ◽  
J. P. Thayer ◽  
K. M. Larson
Keyword(s):  
Geomagnetic Storms ◽  
Low Latitude ◽  
Longitudinal Structure ◽  
Low Latitude Ionosphere

scholarly journals Effects of strong IMF <I>B<sub>z</sub></I> southward events on the equatorial and mid-latitude ionosphere

2009 ◽  
Vol 27 (3) ◽  
pp. 1175-1187 ◽  
Author(s):  
E. Astafyeva
Keyword(s):  
Electric Fields ◽  
Geomagnetic Storms ◽  
The Other ◽  
Negative Events ◽  
Equatorial Anomaly ◽  
Low Latitude ◽  
Sudden Drop ◽  
Ionospheric Response ◽  
Peak Structure ◽  
Low Latitude Ionosphere

Abstract. Dayside ionospheric response to five intense geomagnetic storms (Dst<−120 nT) that occurred in 2001–2005 was investigated by use of simultaneous TEC measurements by the CHAMP, SAC-C, TOPEX/Jason-1 satellites. Since the satellites passed over different longitudinal sectors and measured TEC in different range of altitudes, it was possible to obtain information about altitudinal and longitudinal ionosphere redistribution during these storms. Severe enhancements (up to ~350%) of the equatorial and mid-latitude TEC above ~430 km with concurrent traveling of the equatorial anomaly crests for a distance of 10–15° of latitude were observed during two of the five events analyzed here (6 November 2001 and 8 November 2004). This phenomenon, known as the dayside ionosphere uplift, or the "daytime super-fountain effect", occurred after sudden drop in IMF Bz and consequent penetration of the electric fields to the low-latitude ionosphere. However, the same order Bz negative events caused comparatively weak changes in the dayside TEC (up to ~80 TECU) during the other three events of 18 June 2003, 11 February 2004 and 24 August 2005. At the main phase of these storms there were mostly observed formation of the "typical" dual peak structure of the equatorial anomaly rather than the reinforcement of the fountain effect and the anomaly itself. Possible reasons and factors responsible for the development of the extreme ionosphere effects are discussed in the paper.

scholarly journals Storm-time ionization enhancements at the topside low-latitude ionosphere

2008 ◽  
Vol 26 (4) ◽  
pp. 867-876 ◽  
Author(s):  
A. Dmitriev ◽  
H.-C. Yeh
Keyword(s):  
Radiation Belt ◽  
Temporal Dynamics ◽  
Geomagnetic Storms ◽  
Energetic Particles ◽  
Low Latitude ◽  
Ion Density ◽  
Low Latitude Ionosphere ◽  
Using Data ◽  
Mev Protons ◽  
Earth Radiation

Abstract. Ion density enhancements at the topside low-latitude ionosphere during a Bastille storm on 15–16 July 2000 and Halloween storms on 29–31 October 2003 were studied using data from ROCSAT-1/IPEI experiment. Prominent ion density enhancements demonstrate similar temporal dynamics both in the sunlit and in the nightside hemispheres. The ion density increases dramatically (up to two orders of magnitude) during the main phase of the geomagnetic storms and reaches peak values at the storm maximum. The density enhancements are mostly localized in the region of a South Atlantic Anomaly (SAA), which is characterized by very intense fluxes of energetic particles. The dynamics of near-Earth radiation was studied using SAMPEX/LEICA data on >0.6 MeV electrons and >0.8 MeV protons at around 600 km altitude. During the magnetic storms the energetic particle fluxes in the SAA region and in its vicinity increase more than three orders of magnitude. The location of increased fluxes overlaps well with the regions of ion density enhancements. Two mechanisms were considered to be responsible for the generation of storm-time ion density enhancements: prompt penetration of the interplanetary electric field and abundant ionization of the ionosphere by enhanced precipitation of energetic particles from the radiation belt.

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