@Article{EcherTsurGonzKozy:2011:20Ma16,
               author = "Echer, E. and Tsurutani, Bruce T and Gonzalez, Walter Demetrio and 
                         Kozyra, J.",
          affiliation = "{Instituto Nacional de Pesquisas Espaciais (INPE)} and Jet 
                         Propulsion Laboratory, California Institute of Technology and 
                         {Instituto Nacional de Pesquisas Espaciais (INPE)}",
                title = "High Speed Stream Properties and Related Geomagnetic Activity 
                         During the Whole Heliosphere Interval (WHI): 20 March to 16 April 
                         2008",
              journal = "Solar Physics",
                 year = "2011",
               volume = "xx",
                month = "Mar.",
             keywords = "Solar wind, High-speed streams, Geomagnetic activity, Solar cycle, 
                         Space weather, Whole heliosphere interval, Alfv¨¦n waves, Nested 
                         variances.",
             abstract = "We study the interplanetary features and concomitant geomagnetic 
                         activity of the two high-speed streams (HSSs) selected by the 
                         Whole Heliosphere Interval (WHI) campaign participants: 20 March 
                         to 16 April 2008 in Carrington rotation (CR) 2068. This interval 
                         was chosen to perform a comprehensive study of HSSs and their 
                         geoeffectiveness during this {"}deep{"} solar minimum. The two 
                         HSSs within the interval were characterized by fast solar-wind 
                         speeds (peak values > 600 km s-1) containing large-amplitude 
                         Alfv¨¦nic fluctuations, as is typical of HSSs during normal solar 
                         minima. However, the interplanetary magnetic field (IMF) magnitude 
                         [B o] was exceptionally low (¡{\"O}3 - 5 nT) during these HSSs, 
                         leading to lower than usual IMF B z values. The first HSS (HSS1) 
                         had favorable IMF polarity for geomagnetic activity (negative 
                         during northern Spring). The average AE and Dst for the HSS1 
                         proper (HSS1P) were + 258 nT and - 21 nT, respectively. The second 
                         HSS (HSS2) had a positive sector IMF polarity, one that is less 
                         favorable for geomagnetic activity. The AE and Dst index averages 
                         were + 188 nT and - 7 nT, both lower than corresponding numbers 
                         for the first event, as expected. The HSS1P geomagnetic activity 
                         is comparable to, and the HSS2P geomagnetic activity lower than, 
                         corresponding observations for the previous minimum (1996). Both 
                         events' geomagnetic activities are lower than HSS events 
                         previously studied in the declining phase (in 2003). In general, V 
                         sw was faster for the HSSs in 2008 compared to 1996. The southward 
                         IMF B z was lower in the former. The product of these two 
                         parameters [V sw and IMF B z ] comprises the solar-wind electric 
                         field, which is most directly associated with the energy input 
                         into the magnetosphere during the HSS intervals. Thus the combined 
                         effects led to the solar wind energy input in 2008 being slightly 
                         less than that in 1996. A detailed analysis of magnetic-field 
                         variances and Alfv¨¦nicity is performed to explore the 
                         characteristics of Alfv¨¦n waves (a central element in the 
                         geoeffectiveness of HSSs) during the WHI. The B z variances in the 
                         proto-CIR (PCIR) were ¡{\"O} 30 nT2 and < 10 nT2 in the high 
                         speed streams proper.",
                  doi = "10.1007/s11207-011-9739-0",
                  url = "http://dx.doi.org/10.1007/s11207-011-9739-0",
                 issn = "0038-0938 and 1573-093X",
             language = "en",
        urlaccessdate = "29 jun. 2024"
}