2016/05/31 by Ankush Bhaskar, Prasad Subramanian, Geeta Vichare · 28 citations
Physics and Astronomy · #Advection #Astro and Planetary Science #Astrophysics #Atmospheric sciences #Computational physics #Coronal mass ejection #Cosmic ray #Forbush decrease #Interplanetary magnetic field #Interplanetary spaceflight #Ionosphere and magnetosphere dynamics #Magnetic field #Neutron monitor #Physics #Solar and Space Plasma Dynamics #Solar wind #astro-ph.SR #hep-ex #msc:85-05 #physics.plasm-ph #physics.space-ph
paper · pdf · doi:10.3847/0004-637x/828/2/104
published in The Astrophysical Journal 828(2), 104 (IOP Publishing) · 19 pages, 5 figures, 2 tables, Accepted for publication in ApJ
arxiv created 2016/08/12 · openalex created_date 2016/08/23 · openalex publication_date 2016/09/08 · arxiv updated 2016/09/21 · openalex updated_date 2026/08/06
ABSTRACT We study 50 cosmic-ray Forbush decreases (FDs) from the Oulu neutron monitor data during 1997–2005 that were associated with Earth-directed interplanetary coronal mass ejections (ICMEs). Such events are generally thought to arise due to the shielding of cosmic rays by a propagating diffusive barrier. The main processes at work are the diffusion of cosmic rays across the large-scale magnetic fields carried by the ICME and their advection by the solar wind. In an attempt to better understand the relative importance of these effects, we analyze the relationship between the FD profiles and those of the interplanetary magnetic field ( B ) and the solar wind speed ( V sw ). Over the entire duration of a given FD, we find that the FD profile is generally (anti)correlated with the B and V sw profiles. This trend holds separately for the FD main and recovery phases too. For the recovery phases, however, the FD profile is highly anti-correlated with the V sw profile, but not with the B profile. While the total duration of the FD profile is similar to that of the V sw profile, it is significantly longer than that of the B profile. Using the convection–diffusion model, a significant contribution of advection by solar wind is found during the recovery phases of the FD.