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 = "29 set. 2020"