Superposed epoch study of ICME sub-structures near Earth and their effects on Galactic cosmic rays
Context. Interplanetary coronal mass ejections (ICMEs) are the interplanetary manifestations of solar eruptions. The overtaken solar wind forms a sheath of compressed plasma at the front of ICMEs. Magnetic clouds (MCs) are a subset of ICMEs with specific properties (e.g. the presence of a flux rope)...
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paper:paper_00046361_v592_n_p_MasiasMeza2023-06-08T14:28:15Z Superposed epoch study of ICME sub-structures near Earth and their effects on Galactic cosmic rays Dasso, Sergio Ricardo Cosmic rays Solar wind Solar-terrestrial relations Sun: coronal mass ejections Sun: heliosphere Sun: magnetic fields Cosmic rays Cosmology Magnetic fields Magnetism Planetary surface analysis Solar system Solar wind Time series analysis Galactic cosmic rays Interplanetary coronal mass ejections Quantitative modeling Solar-terrestrial relations Sun: coronal mass ejection Sun: heliosphere Sun: magnetic field Superposed-epoch analysis Magnetoplasma Context. Interplanetary coronal mass ejections (ICMEs) are the interplanetary manifestations of solar eruptions. The overtaken solar wind forms a sheath of compressed plasma at the front of ICMEs. Magnetic clouds (MCs) are a subset of ICMEs with specific properties (e.g. the presence of a flux rope). When ICMEs pass near Earth, ground observations indicate that the flux of Galactic cosmic rays (GCRs) decreases. Aims. The main aims of this paper are to find common plasma and magnetic properties of different ICME sub-structures and which ICME properties affect the flux of GCRs near Earth. Methods. We used a superposed epoch method applied to a large set of ICMEs observed in situ by the spacecraft ACE, between 1998 and 2006. We also applied a superposed epoch analysis on GCRs time series observed with the McMurdo neutron monitors. Results. We find that slow MCs at 1 AU have on average more massive sheaths. We conclude that this is because they are more effectively slowed down by drag during their travel from the Sun. Slow MCs also have a more symmetric magnetic field and sheaths expanding similarly as their following MC, while in contrast, fast MCs have an asymmetric magnetic profile and a sheath in compression. In all types of MCs, we find that the proton density and the temperature and the magnetic fluctuations can diffuse within the front of the MC due to 3D reconnection. Finally, we derive a quantitative model that describes the decrease in cosmic rays as a function of the amount of magnetic fluctuations and field strength. Conclusions. The obtained typical profiles of sheath, MC and GCR properties corresponding to slow, middle, and fast ICMEs, can be used for forecasting or modelling these events, and to better understand the transport of energetic particles in ICMEs. They are also useful for improving future operative space weather activities. © 2016 ESO. Fil:Dasso, S. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. 2016 https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00046361_v592_n_p_MasiasMeza http://hdl.handle.net/20.500.12110/paper_00046361_v592_n_p_MasiasMeza |
| institution |
Universidad de Buenos Aires |
| institution_str |
I-28 |
| repository_str |
R-134 |
| collection |
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) |
| topic |
Cosmic rays Solar wind Solar-terrestrial relations Sun: coronal mass ejections Sun: heliosphere Sun: magnetic fields Cosmic rays Cosmology Magnetic fields Magnetism Planetary surface analysis Solar system Solar wind Time series analysis Galactic cosmic rays Interplanetary coronal mass ejections Quantitative modeling Solar-terrestrial relations Sun: coronal mass ejection Sun: heliosphere Sun: magnetic field Superposed-epoch analysis Magnetoplasma |
| spellingShingle |
Cosmic rays Solar wind Solar-terrestrial relations Sun: coronal mass ejections Sun: heliosphere Sun: magnetic fields Cosmic rays Cosmology Magnetic fields Magnetism Planetary surface analysis Solar system Solar wind Time series analysis Galactic cosmic rays Interplanetary coronal mass ejections Quantitative modeling Solar-terrestrial relations Sun: coronal mass ejection Sun: heliosphere Sun: magnetic field Superposed-epoch analysis Magnetoplasma Dasso, Sergio Ricardo Superposed epoch study of ICME sub-structures near Earth and their effects on Galactic cosmic rays |
| topic_facet |
Cosmic rays Solar wind Solar-terrestrial relations Sun: coronal mass ejections Sun: heliosphere Sun: magnetic fields Cosmic rays Cosmology Magnetic fields Magnetism Planetary surface analysis Solar system Solar wind Time series analysis Galactic cosmic rays Interplanetary coronal mass ejections Quantitative modeling Solar-terrestrial relations Sun: coronal mass ejection Sun: heliosphere Sun: magnetic field Superposed-epoch analysis Magnetoplasma |
| description |
Context. Interplanetary coronal mass ejections (ICMEs) are the interplanetary manifestations of solar eruptions. The overtaken solar wind forms a sheath of compressed plasma at the front of ICMEs. Magnetic clouds (MCs) are a subset of ICMEs with specific properties (e.g. the presence of a flux rope). When ICMEs pass near Earth, ground observations indicate that the flux of Galactic cosmic rays (GCRs) decreases. Aims. The main aims of this paper are to find common plasma and magnetic properties of different ICME sub-structures and which ICME properties affect the flux of GCRs near Earth. Methods. We used a superposed epoch method applied to a large set of ICMEs observed in situ by the spacecraft ACE, between 1998 and 2006. We also applied a superposed epoch analysis on GCRs time series observed with the McMurdo neutron monitors. Results. We find that slow MCs at 1 AU have on average more massive sheaths. We conclude that this is because they are more effectively slowed down by drag during their travel from the Sun. Slow MCs also have a more symmetric magnetic field and sheaths expanding similarly as their following MC, while in contrast, fast MCs have an asymmetric magnetic profile and a sheath in compression. In all types of MCs, we find that the proton density and the temperature and the magnetic fluctuations can diffuse within the front of the MC due to 3D reconnection. Finally, we derive a quantitative model that describes the decrease in cosmic rays as a function of the amount of magnetic fluctuations and field strength. Conclusions. The obtained typical profiles of sheath, MC and GCR properties corresponding to slow, middle, and fast ICMEs, can be used for forecasting or modelling these events, and to better understand the transport of energetic particles in ICMEs. They are also useful for improving future operative space weather activities. © 2016 ESO. |
| author |
Dasso, Sergio Ricardo |
| author_facet |
Dasso, Sergio Ricardo |
| author_sort |
Dasso, Sergio Ricardo |
| title |
Superposed epoch study of ICME sub-structures near Earth and their effects on Galactic cosmic rays |
| title_short |
Superposed epoch study of ICME sub-structures near Earth and their effects on Galactic cosmic rays |
| title_full |
Superposed epoch study of ICME sub-structures near Earth and their effects on Galactic cosmic rays |
| title_fullStr |
Superposed epoch study of ICME sub-structures near Earth and their effects on Galactic cosmic rays |
| title_full_unstemmed |
Superposed epoch study of ICME sub-structures near Earth and their effects on Galactic cosmic rays |
| title_sort |
superposed epoch study of icme sub-structures near earth and their effects on galactic cosmic rays |
| publishDate |
2016 |
| url |
https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00046361_v592_n_p_MasiasMeza http://hdl.handle.net/20.500.12110/paper_00046361_v592_n_p_MasiasMeza |
| work_keys_str_mv |
AT dassosergioricardo superposedepochstudyoficmesubstructuresnearearthandtheireffectsongalacticcosmicrays |
| _version_ |
1768546186531176448 |