@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 = "30 abr. 2024"
}