caa a22 4500 445346922 CHVBK 20180317142831.0 cr unu---uuuuu 170323e20111201xx s 000 0 eng 10.1007/s11207-011-9739-0 doi (NATIONALLICENCE)springer-10.1007/s11207-011-9739-0 High Speed Stream Properties and Related Geomagnetic Activity During the Whole Heliosphere Interval (WHI): 20 March to 16 April 2008 [Elektronische Daten] [E. Echer, B. Tsurutani, W. Gonzalez, J. Kozyra] 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 > 600km s−1) containing large-amplitude Alfvénic fluctuations, as is typical of HSSs during normal solar minima. However, the interplanetary magnetic field (IMF) magnitude [B o] was exceptionally low (≈3 - 5nT) 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 + 258nT and − 21nT, 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 + 188nT and − 7nT, 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. Adetailed analysis of magnetic-field variances and Alfvénicity is performed to explore the characteristics of Alfvén waves (acentral element in the geoeffectiveness of HSSs) during the WHI. The B z variances in the proto-CIR (PCIR) were ≈ 30nT2 and < 10nT2 in the high speed streams proper. Springer Science+Business Media B.V., 2011 Solar wind nationallicence High-speed streams nationallicence Geomagnetic activity nationallicence Solar cycle nationallicence Space weather nationallicence Whole heliosphere interval nationallicence Alfvén waves nationallicence Nested variances nationallicence Echer E. National Institute for Space Research (INPE), Sao Jose dos Campos, SP, Brazil aut Tsurutani B. National Institute for Space Research (INPE), Sao Jose dos Campos, SP, Brazil aut Gonzalez W. National Institute for Space Research (INPE), Sao Jose dos Campos, SP, Brazil aut Kozyra J. University of Michigan, Ann Arbor, MI, USA aut Solar Physics Springer Netherlands 274/1-2(2011-12-01), 303-320 0038-0938 274:1-2<303 2011 274 11207 https://doi.org/10.1007/s11207-011-9739-0 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s11207-011-9739-0 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Echer E. National Institute for Space Research (INPE), Sao Jose dos Campos, SP, Brazil aut NATIONALLICENCE 700 1- Tsurutani B. National Institute for Space Research (INPE), Sao Jose dos Campos, SP, Brazil aut NATIONALLICENCE 700 1- Gonzalez W. National Institute for Space Research (INPE), Sao Jose dos Campos, SP, Brazil aut NATIONALLICENCE 700 1- Kozyra J. University of Michigan, Ann Arbor, MI, USA aut NATIONALLICENCE 773 0- Solar Physics Springer Netherlands 274/1-2(2011-12-01), 303-320 0038-0938 274:1-2<303 2011 274 11207 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer