Astronomy and Astrophysics – Astrophysics
Scientific paper
Jun 2007
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2007jgra..11206112g&link_type=abstract
Journal of Geophysical Research, Volume 112, Issue A6, CiteID A06112
Astronomy and Astrophysics
Astrophysics
43
Space Weather: Magnetic Storms (2788), Solar Physics, Astrophysics, And Astronomy: Coronal Mass Ejections (2101), Solar Physics, Astrophysics, And Astronomy: Solar Activity Cycle (2162), Solar Physics, Astrophysics, And Astronomy: Flares, Solar Physics, Astrophysics, And Astronomy: Magnetic Fields
Scientific paper
We studied the geoeffectiveness, speed, solar source, and flare association of a set of 378 halo coronal mass ejections (CMEs) of cycle 23 (1996-2005, inclusive). We compiled the minimum Dst values occurring within 1-5 days after the CME onset. We compared the distributions of such Dst values for the following subsets of halo CMEs: disk halos (within 45 deg from disk center), limb halos (beyond 45 degrees but within 90 deg from disk center), and backside halo CMEs. Defining that a halo CME is geoeffective if it is followed by Dst <= -50 nT, moderately geoeffective if -50 nT < Dst < -100 nT, and strongly geoeffective if Dst <= -100 nT, we find that the disk halos are followed by strong storms, limb halos are followed by moderate storms, and backside halos are not followed by significant storms. The Dst distribution for a random sample is nearly identical to the case of backside halos. About 71% of all frontside halos are geoeffective, supporting the high rate of geoeffectiveness of halo CMEs. A larger fraction (75%) of disk halos are geoeffective. Intense storms are generally due to disk halos and the few intense storms from limb halos occur only in the maximum and declining phases. Most intense storms occur when there are successive CMEs. The delay time between CME onset and minimum Dst value is the smallest for limb halos, suggesting that the sheath is geoeffective in these cases. The geoeffectiveness rate has prominent dips in 1999 and 2002 (the beginning and end years of the solar maximum phase). The numbers of all frontside and geoeffective frontside halos show a triple peak structure similar to the number of intense geomagnetic storms. The difference in flare sizes among geoeffective and nongeoeffective halos is not significant. The nongeoeffective CMEs are generally slower and have more easterly or limbward solar sources compared to the geoeffective ones; source location and speed are the most important parameters for geoeffectiveness.
Akiyama Sanae
Gopalswamy Nat
Yashiro Seiji
No associations
LandOfFree
Geoeffectiveness of halo coronal mass ejections 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 Geoeffectiveness of halo coronal mass ejections, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Geoeffectiveness of halo coronal mass ejections will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-881813