 |
| Titel |
Studies of ionospheric F-region response in the Latin American sector during the geomagnetic storm of 21-22 January 2005 |
| VerfasserIn |
Y. Sahai, P. R. Fagundes, R. Jesus, A. J. Abreu, G. Crowley, T. Kikuchi, C.-S. Huang, V. G. Pillat, F. L. Guarnieri, J. R. Abalde, J. A. Bittencourt |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
0992-7689
|
| Digitales Dokument |
URL |
| Erschienen |
In: Annales Geophysicae ; 29, no. 5 ; Nr. 29, no. 5 (2011-05-27), S.919-929 |
| Datensatznummer |
250017026
|
| Publikation (Nr.) |
 copernicus.org/angeo-29-919-2011.pdf |
|
|
|
|
|
| Zusammenfassung |
| In the present investigation, we have studied the response of the
ionospheric F-region in the Latin American sector during the intense
geomagnetic storm of 21–22 January 2005. This geomagnetic storm has been
considered "anomalous" (minimum Dst reached −105 nT at 07:00 UT on 22
January) because the main storm phase occurred during the northward
excursion of the Bz component of interplanetary magnetic fields (IMFs). The
monthly mean F10.7 solar flux for the month of January 2005 was 99.0 sfu.
The F-region parameters observed by ionosondes at Ramey (RAM; 18.5° N,
67.1° W), Puerto Rico, Jicamarca (JIC; 12.0° S, 76.8° W),
Peru, Manaus (MAN; 2.9° S, 60.0° W), and São José dos
Campos (SJC; 23.2° S, 45.9° W), Brazil, during 21–22 January
(geomagnetically disturbed) and 25 January (geomagnetically quiet) have been
analyzed. Both JIC and MAN, the equatorial stations, show unusually rapid
uplifting of the F-region peak heights (hpF2/hmF2) and a decrease in the
NmF2 coincident with the time of storm sudden commencement (SSC). The
observed variations in the F-region ionospheric parameters are compared with
the TIMEGCM model run for 21–22 January and the model results show both
similarities and differences from the observed results. Average GPS-TEC (21,
22 and 25 January) and phase fluctuations (21, 22, 25, 26 January) observed
at Belem (BELE; 1.5° S, 48.5° W), Brasilia (BRAZ; 15.9° S,
47.9° W), Presidente Prudente (UEPP; 22.3° S, 51.4° W), and
Porto Alegre (POAL; 30.1° S, 51.1° W), Brazil, are also presented.
These GPS stations belong to the RBMC/IBGE network of Brazil. A few hours
after the onset of the storm, large enhancements in the VTEC and NmF2
between about 20:00 and 24:00 UT on 21 January were observed at all the
stations. However, the increase in VTEC was greatest at the near equatorial
station (BELE) and enhancements in VTEC decreased with latitude. It should
be pointed out that no phase fluctuations or spread-F were observed in the
Latin American sector during the post-sunset pre-reversal time in the
geomagnetic disturbance (21 January). The disturbance dynamo electric field
possibly resulted in downward drift of the F-region plasma and inhibited the
formation of spread-F. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|