@InProceedings{WrasseEcheDalLFech:2007:HiSpSt,
author = "Wrasse, Cristiano Max and Echer, Ezequiel and Dal Lago, Alisson
and Fechine, Joaquim",
affiliation = "UNIVAP and {Instituto Nacional de Pesquisas Espaciais (INPE)} and
{Instituto Nacional de Pesquisas Espaciais (INPE)} and {Instituto
Nacional de Pesquisas Espaciais (INPE)}",
title = "High speed streams and geomagnetic activity recurrency during
different solar cycles revealed by wavelet analysis",
year = "2007",
organization = "Encontro Brasileiro de F{\'{\i}}sica dos Plasmas, 9.",
abstract = "Solar wind velocity and the geomagnetic index Ap are used to
verify the recurrency of the high speed streams and the
geomagnetic activity in diŽerent solar cycles. The wavelet
technique is used to perform the spectral analysis of the solar
wind velocity, interplanetary magnetic ¯eld parameters and
geomagnetic index with 1-day resolution. The Ap index between 1978
and 2003 is also used. The solar wind velocity data come from
three diŽerent instruments in order to access diŽerent time
periods and solar cycles. The ISEE-3 is used for the period of
1978-1982. The WIND satellite is used for 1995-1997 and the ACE
satellite is used for 1998-2002 period. The results suggest that
the semi-annual variation in Ap index is stronger during
descending phase of the solar cycle, while the annual variation in
Ap is stronger during solar cycle 22 (1989-1990) maximum than
during solar cycles 21 and 23. It is also observed that the 27-day
periodicity is stronger for ~B components than for ~V components
around 1998-2002. A semi-annual variation is clearly observed in
~V components than in ~B components around 1998-2002. Regarding
the 27-day variation in solar wind speed and magnetic ¯eld
strength, it can be seen that this periodicity is more visible in
~V than in ~B . This periodicity is also more stable (it exists
for more time) during the 1995-1997 minimum than during the
1978-1982 maximum.",
conference-location = "S{\~a}o Pedro, SP",
conference-year = "25-28 Nov.",
language = "pt",
urlaccessdate = "16 jun. 2024"
}