INVESTIGADORES
GENDE Mauricio Alfredo
artículos
Título:
Traveling planetary wave ionospheric disturbances and their role in the generation of equatorial spread-F and GPS phase fluctuations during the last extreme low solar activity and comparison with high solar activity
Autor/es:
DE ABREU, A. J.; FAGUNDES, P. R.; BOLZAN, M. J. A.; GENDE, M.; BRUNINI, C.; DE JESUS, R.; PILLAT, V. G.; ABALDE, J. R.; LIMA, W. L. C.
Revista:
JOURNAL OF ATMOSPHERIC AND SOLAR-TERRESTRIAL PHYSICS
Editorial:
PERGAMON-ELSEVIER SCIENCE LTD
Referencias:
Lugar: Amsterdam; Año: 2014 vol. 117 p. 7 - 19
ISSN:
1364-6826
Resumen:
This investigation studies traveling planetary wave ionospheric disturbance (TPWID) type oscillations on the
modulation of the F region virtual height rise during the EB electric field pre-reversal enhancement (PRE),
near sunset hours. We also studied their role in the generation of equatorial spread F (ESF) and GPS phase
fluctuations during periods of the last extreme low solar activity (LSA) of January 2009 to April 2010
ðF10:7 ¼73Þ. A comparison ismadewith periods of high solar activity (HSA) in 2003 and 2004 near equatorial
region. The ionospheric irregularities investigated are medium (bottom-side) and large (plasma bubble) scales.
Ionospheric F region oscillations with period of days are due to the TPWIDs, which play an important role in
producing favorable or unfavorable conditions for equatorial ionospheric irregularities, changing the electron
vertical profile and F region height. In this paper, we present simultaneous ionospheric sounding (ionosonde)
and GPS vertical total electron content (vTEC) observations carried out near equatorial region (Palmas 10.21S,
48.21W) and lowlatitude region (São José dos Campos 23.21S, 45.91W; located under the southern crest of the
equatorial ionospheric anomaly), Brazil. Observations show that the occurrence of fresh ESF during LSA and
HSA and fresh GPS phase fluctuations at equatorial region follow the trend of day-to-day variations in the
F region virtual height, which are due to electric field PREmodulated by TPWID wave like oscillations. During
LSA, the altitude of 250 km acts as a threshold height for the generation of fresh ionospheric irregularities,
whereas during HSA, the threshold height is 300 km. The observations also found a strong increase in the
generation of fresh ionospheric irregularities from October 2009 to March 2010 during LSA and from
September 2003 to March 2004 during the HSA. Furthermore, in LSA, the period of fresh ionospheric
irregularities was less than during HSA, though both periods followed a similar seasonal pattern. In the low-
latitude, we observed more ESFs than phase fluctuations because ionosonde is more sensitive than GPS. We
also observed periodswith and without day-to-day oscillations in the F region virtual height. The observations
made by GPS stations and ionosondes in the equatorial region, for much of the period analyzed, presented
similar results with regard to the generation of equatorial ionospheric irregularities. In the low latitude, some
nights of January, February, October, and December 2009 also showed a similarity.