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@Article{TsurutaniEcheGuarGonz:2011:PrTwSo,
               author = "Tsurutani, Bruce T. and Echer, Ezequiel and Guarnieri, Fernando L. 
                         and Gonzalez Alarcon, Walter Dem{\'e}trio",
          affiliation = "CALTECH, Jet Prop Lab, Pasadena, CA 91125 USA and {Instituto 
                         Nacional de Pesquisas Espaciais (INPE)} and {Universidade do Vale 
                         do Paraiba (UNIVAP)} and {Instituto Nacional de Pesquisas 
                         Espaciais (INPE)}",
                title = "The properties of two solar wind high speed streams and related 
                         geomagnetic activity during the declining phase of solar cycle 
                         23",
              journal = "Journal of Atmospheric and Solar-Terrestrial Physics",
                 year = "2011",
               volume = "73",
               number = "1",
                pages = "164--177",
                month = "Jan.",
             keywords = "High speed solar wind streams, Interplanetary Alfvenicity, 
                         Geomagnetic activity, HILDCAAs.",
             abstract = "Two high speed stream (HSS) solar wind intervals (days 283¨C294 
                         and 314¨C318, 2003, hereafter called Events 1 and 2) during the 
                         declining phase of solar cycle 23 have been examined in detail for 
                         their interplanetary characteristics and their resultant 
                         geomagnetic activity. Event 1 had an associated storm initial 
                         phase with peak Dst=+9 nT. This was caused by a high plasma 
                         density heliospheric plasma sheet (HPS) which impacted the 
                         magnetosphere. The southward component of IMF Bz fluctuations in 
                         the corotating interaction regions (CIRs) of both Events 1 and 2 
                         led to peak storm main phases of Dst=\−85 and \−62 
                         nT, respectively. The extended storm ¡°recovery¡± phases were 
                         associated with ¦¤B/Bo 1¨C2 Alfv¨¦nic fluctuations in the HSS 
                         proper. High-intensity, long-duration, continuous AE (HILDCAA) 
                         intervals were present, presumably due to the southward component 
                         of the Alfv¨¦n waves. The IMF Bx¨CVx 4-h cross-correlation values 
                         were >0.8 in Event 2, and lower, >0.6, in Event 1. The difference 
                         in Alfv¨¦nicity between the two HSS events is not understood at 
                         present. The IMF Bz 10-min to 3-h variances and are highest during 
                         the CIRs. The normalized variances during the HSS proper are 
                         approximately the same as those for the CIRs. For Event 1, the 1-h 
                         IMF and are 5.0 nT2 and 1.1¡{\'A}10\−1, respectively. The 
                         IMF Bz-AE cross-correlation (c.c.) coefficients during the storm 
                         main phase of Event 1 and for 24-h of the HSS of Event 2 give 
                         similar results. For the Event 1, a peak c.c. of \−0.4 
                         occurred with a lag of 103 min, and for Event 2 a peak c.c of 
                         \−0.38 with a lag of 67 min was obtained. Both c.c. results 
                         were sharply peaked. The decay-portion of a HSS prior to Event 1 
                         was characterized by low Np, low Bo and low Alfv¨¦n wave 
                         amplitudes. The 1-h IMF and were 0.84 nT2 and 
                         2.9¡{\'A}10\−2, respectively. This quiet interplanetary 
                         interval led to a quiet geomagnetic activity period (AE<100 nT, 
                         Dst +5 nT). On the other hand, what is quite surprising is that 
                         this region was the most purely ¡°Alfv¨¦nic¡± interval studied 
                         (c.c. of Bx-Vx=0.95).The ¦Å parameter was calculated using both 
                         GSE and GSM coordinates. It was found that ¦Å is 30% larger for 
                         GSM coordinates. Thus, the major cause of geomagnetic activity 
                         during HSSs is the large amplitude Alfv¨¦n waves but not 
                         coordinate transformations. Sector polarities (IMF By values) may 
                         be a secondary factor. However, other models, like the tilted 
                         solar dipole, should be considered as well.",
                  doi = "10.1016/j.jastp.2010.04.003",
                  url = "http://dx.doi.org/10.1016/j.jastp.2010.04.003",
                 issn = "1364-6826",
             language = "en",
           targetfile = "the properties of two solar.pdf",
        urlaccessdate = "25 jul. 2021"
}


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