%0 Conference Proceedings
%4 sid.inpe.br/mtc-m17@80/2007/
%2 sid.inpe.br/mtc-m17@80/2007/
%A Wrasse, Cristiano Max,
%A Echer, Ezequiel,
%A Dal Lago, Alisson,
%A Fechine, Joaquim,
%@affiliation UNIVAP
%@affiliation Instituto Nacional de Pesquisas Espaciais (INPE)
%@affiliation Instituto Nacional de Pesquisas Espaciais (INPE)
%@affiliation Instituto Nacional de Pesquisas Espaciais (INPE)
%T High speed streams and geomagnetic activity recurrency during different solar cycles revealed by wavelet analysis
%B Encontro Brasileiro de Física dos Plasmas, 9.
%D 2007
%8 25-28 Nov.
%C São Pedro, SP
%X Solar wind velocity and the geomagnetic index Ap are used to verify the recurrency of the high speed streams and the geomagnetic activity in di®erent 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 di®erent instruments in order to access di®erent 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.
%@language pt