The properties of two solar wind high speed streams and related geomagnetic activity during the declining phase of solar cycle 23

Details The properties of two solar wind high speed streams and related geomagnetic activity during the declining phase of solar cycle 23 The properties of two solar wind high speed streams and related geomagnetic activity during the declining phase of solar cycle 23

Jan 2011

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2011jastp..73..164t&link_type=abstract

Journal of Atmospheric and Solar-Terrestrial Physics, Volume 73, Issue 1, p. 164-177.

Physics

2

Scientific paper

Two high speed stream (HSS) solar wind intervals (days 283-294 and 314-318, 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 ΔB/Bo ˜1-2 Alfvénic fluctuations in the HSS proper. High-intensity, long-duration, continuous AE (HILDCAA) intervals were present, presumably due to the southward component of the Alfvén waves. The IMF Bx-Vx 4-h cross-correlation values were >0.8 in Event 2, and lower, >0.6, in Event 1. The difference in Alfvénicity between the two HSS events is not understood at present. The IMF Bz 10-min to 3-h variances (σz2) and are highest during the CIRs. The normalized variances (σz2/Bo2) during the HSS proper are approximately the same as those for the CIRs. For Event 1, the 1-h IMF σz2 and σz2/Bo2 are 5.0 nT2 and 1.1×10-1, 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 Alfvén wave amplitudes. The 1-h IMF σz2 and σz2/Bo2 were 0.84 nT2 and 2.9×10-2, 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 “Alfvénic” interval studied (c.c. of Bx-Vx=0.95). The ɛ parameter was calculated using both GSE and GSM coordinates. It was found that ɛ is ˜30% larger for GSM coordinates. Thus, the major cause of geomagnetic activity during HSSs is the large amplitude Alfvén 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.

Affiliated with

Also associated with

No associations

Rating

The properties of two solar wind high speed streams and related geomagnetic activity during the declining phase of solar cycle 23 does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with The properties of two solar wind high speed streams and related geomagnetic activity during the declining phase of solar cycle 23, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and The properties of two solar wind high speed streams and related geomagnetic activity during the declining phase of solar cycle 23 will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-1597693