2020/09/13 by Fithanegest Kassa Dagnew, N. Gopalswamy, Dagnew, Fithanegest Kassa +9
Earth and Planetary Sciences · Physics and Astronomy · #FOS: Physical sciences #Geophysics and Gravity Measurements #Solar and Space Plasma Dynamics #Solar and Stellar Astrophysics (astro-ph.SR) #Stellar, planetary, and galactic studies
paper · pdf · doi:10.48550/arxiv.2009.06033
openalex publication_date 2020/09/13 · openalex created_date 2022/07/25 · openalex updated_date 2026/07/28
We report on the properties of halo coronal mass ejections (HCMEs) in solar\ncycles 23 and 24. We compare the HCMEs properties between the corresponding\nphases (rise, maximum, and declining) in cycles 23 and 24 in addition to\ncomparing those between the whole cycles. Despite the significant decline in\nthe sunspot number (SSN) in cycle 24, which dropped by 46% with respect to\ncycle 23, the abundance of HCMEs is similar in the two cycles. The HCME rate\nper SSN is 44% higher in cycle 24. In the maximum phase, cycle-24 rate\nnormalized to SSN increased by 127% while the SSN dropped by 43%. The source\nlongitudes of cycle-24 HCMEs are more uniformly distributed than those in cycle\n23. We found that the average sky-plane speed in cycle 23 is ~16% higher than\nthat in cycle 24. The size distributions of the associated flares between the\ntwo cycles and the corresponding phases are similar. The average speed at a\ncentral meridian distance (CMD) = 600 for cycle 23 is ~28% higher than that of\ncycle 24. We discuss the unusual bump in HCME activity in the declining phase\nof cycle 23 as due to exceptional active regions that produced many CMEs during\nOctober 2003 to October 2005. The differing HCME properties in the two cycles\ncan be attributed to the anomalous expansion of cycle-24 CMEs. Considering the\nHCMEs in the rise, maximum and declining phases, we find that the maximum phase\nshows the highest contrast between the two cycles.\n