scholarly journals The Two-step Forbush Decrease: A Tale of Two Substructures Modulating Galactic Cosmic Rays within Coronal Mass Ejections

2021 ◽  
Vol 922 (2) ◽  
pp. 216
Author(s):  
Miho Janvier ◽  
Pascal Démoulin ◽  
Jingnan Guo ◽  
Sergio Dasso ◽  
Florian Regnault ◽  
...  
Keyword(s):  
Cosmic Rays ◽  
Coronal Mass Ejections ◽  
Forbush Decrease ◽  
Recovery Phase ◽  
Galactic Cosmic Rays ◽  
Space Environment ◽  
Interplanetary Coronal Mass Ejections ◽  
Superposed Epoch Analysis ◽  
Epoch Analysis

Abstract Interplanetary coronal mass ejections (ICMEs) are known to modify the structure of the solar wind as well as interact with the space environment of planetary systems. Their large magnetic structures have been shown to interact with galactic cosmic rays (GCRs), leading to the Forbush decrease (FD) phenomenon. We revisit in the present article the 17 yr of Advanced Composition Explorer spacecraft ICME detection along with two neutron monitors (McMurdo and Oulu) with a superposed epoch analysis to further analyze the role of the magnetic ejecta in driving FDs. We investigate in the following the role of the sheath and the magnetic ejecta in driving FDs, and we further show that for ICMEs without a sheath, a magnetic ejecta only is able to drive significant FDs of comparable intensities. Furthermore, a comparison of samples with and without a sheath with similar speed profiles enable us to show that the magnetic field intensity, rather than its fluctuations, is the main driver for the FD. Finally, the recovery phase of the FD for isolated magnetic ejecta shows an anisotropy in the level of the GCRs. We relate this finding at 1 au to the gradient of the GCR flux found at different heliospheric distances from several interplanetary missions.

scholarly journals Statistical analysis of storm-time near-Earth current systems

2015 ◽  
Vol 33 (8) ◽  
pp. 965-982 ◽  
Author(s):  
M. W. Liemohn ◽  
R. M. Katus ◽  
R. Ilie
Keyword(s):  
Electric Field ◽  
Ring Current ◽  
Recovery Phase ◽  
Hot Electron ◽  
Early Recovery ◽  
Superposed Epoch Analysis ◽  
Tail Current ◽  
Near Earth Space ◽  
Epoch Analysis ◽  
Current Systems

Abstract. Currents from the Hot Electron and Ion Drift Integrator (HEIDI) inner magnetospheric model results for all of the 90 intense storms (disturbance storm-time (Dst) minimum < −100 nT) from solar cycle 23 (1996–2005) are calculated, presented, and analyzed. We have categorized these currents into the various systems that exist in near-Earth space, specifically the eastward and westward symmetric ring current, the partial ring current, the banana current, and the tail current. The current results from each run set are combined by a normalized superposed epoch analysis technique that scales the timeline of each phase of each storm before summing the results. It is found that there is a systematic ordering to the current systems, with the asymmetric current systems peaking during storm main phase (tail current rising first, then the banana current, followed by the partial ring current) and the symmetric current systems peaking during the early recovery phase (westward and eastward symmetric ring current having simultaneous maxima). The median and mean peak amplitudes for the current systems ranged from 1 to 3 MA, depending on the setup configuration used in HEIDI, except for the eastward symmetric ring current, for which the mean never exceeded 0.3 MA for any HEIDI setup. The self-consistent electric field description in HEIDI yielded larger tail and banana currents than the Volland–Stern electric field, while the partial and symmetric ring currents had similar peak values between the two applied electric field models.

Decadal Cooling of East Asia – the Role of Aerosols and Ozone Produced by Galactic Cosmic Rays

2018 ◽  
Author(s):  
Natalya A. Kilifarska ◽  
Tijian Wang ◽  
Kostadin Ganev ◽  
Min Xie ◽  
Bingliang Zhuang ◽  
...  
Keyword(s):  
Cosmic Rays ◽  
East Asia ◽  
Galactic Cosmic Rays

A new model describing Forbush Decreases at Mars: combining the heliospheric modulation and the atmospheric influence

2020 ◽  
Author(s):  
Jingnan Guo ◽  
Robert Wimmer-Schweingruber ◽  
Mateja Dumbovic ◽  
Bernd Heber ◽  
Yuming Wang
Keyword(s):  
Interplanetary Space ◽  
Atmospheric Transport ◽  
Forbush Decrease ◽  
Martian Atmosphere ◽  
Galactic Cosmic Rays ◽  
Interplanetary Coronal Mass Ejections ◽  
Forbush Decreases ◽  
Mars Atmosphere ◽  
Interaction Regions ◽  
Energy Dependent

&lt;p&gt;Forbush decreases are depressions in the galactic cosmic rays (GCRs) which are mostly caused by the modulations of interplanetary coronal mass ejections (ICMEs) and also sometimes by stream/corotating interaction regions (SIRs/CIRs). Forbush decreases have been studied extensively using neutron monitors at Earth and have been recently, for the first time, measured on the surface of another planet - Mars by the Radiation Assessment Detector (RAD), on board Mars Science Laboratory&amp;#8217;s (MSL) rover Curiosity. The modulation of the GCR particles by heliospheric transients in space is energy-dependent and afterwards these particles are also interacting with the Martian atmosphere with the interaction process depending on the particle type and energy. In order to study the space weather environment near Mars using the ground-measured Forbush decreases, it is important to understand and quantify the energy-dependent modulation of the GCR particles by not only the pass-by heliospheric disturbances but also the Martian atmosphere. In this study, we develop a model which combines the heliospheric modulation of GCRs and the atmospheric modification of such modulated GCR spectra to quantify the amplitudes of the Forbush decreases at Mars: both on ground and in the interplanetary space near Mars during the pass-by of an ICME/SIR. The modeled results are in good agreement when compared to studies of Forbush decreases caused by ICMEs/SIRs measured by MSL on the surface of Mars and by the Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft in orbit. &amp;#160;This supports the validity of both the Forbush decrease description and the Martian atmospheric transport models.&amp;#160; Our model can be potentially used to understand the property of ICMEs and SIRs passing Mars.&lt;/p&gt;

About the role of the Sun magnetic field characteristics in the long-term galactic cosmic rays modulation

2009 ◽  
Vol 73 (3) ◽  
pp. 334-336
Author(s):  
R. T. Gushchina ◽  
A. V. Belov ◽  
V. N. Obridko ◽  
B. D. Shelting
Keyword(s):  
Magnetic Field ◽  
Cosmic Rays ◽  
Galactic Cosmic Rays ◽  
The Sun
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