Testing the simultaneity of Forbush decreases with algorithm-selected Forbush event catalogue

Alhassan, J. A.; Okike, O.; Chukwude, A. E.

doi:10.1007/s12036-021-09790-8

Cited by 8 publications

(6 citation statements)

References 50 publications

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“…The baseline adopted determines the number of FDs that may be selected in a given period (see Okike & Umahi 2019). Using a very small baseline (CR(%) ≤ −0.01), as attempted by Okike (2020c), Okike et al (2021) and Paper I, the software identified 408 and 383 FDs respectively from MOSC and APTY neutron monitor stations.…”

Section: Fd Location Progammentioning

confidence: 99%

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Investigation of the Relation between Space-Weather Parameters and Forbush Decreases Automatically Selected from Moscow and Apatity Cosmic Ray Stations during Solar Cycle 23

Alhassan,

Okike,

Chukwude

2021

Preprint

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We present the results of an investigation of the relation between space-weather parameters and cosmic ray (CR) intensity modulation using algorithm-selected Forbush decreases (FDs) from Moscow (MOSC) and Apatity (APTY) neutron monitor (NM) stations during solar cycle 23. Our FD location program detected 408 and 383 FDs from MOSC and APTY NM stations respectively. A coincident computer code employed in this work, detected 229 FDs that were observed at the same universal Time (UT) at the two stations. Out of the 229 simultaneous FDs, we formed a subset of 139 large FDs(%) ≤ −4 at Moscow station. We peformed a two dimensional regression analysis between the FD magnitudes and the space-weather data on the two samples. We find that there were significant space-weather disturbances at the time of the CR flux depressions. The correlation between the space-weather parameters and galactic cosmic ray (GCR) intensity decreases at the two NM stations are statistically significant. The implications of the present space-weather data on cosmic ray (CR) intensity depressions are highlighted.

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Section: Fd Location Progammentioning

confidence: 99%

“…Solar cycle 23 falls within the satellite period. It is well investigated and marked with high solar activity (Okike et al 2021). Observations during this period are reported to be related to several coronal holes that trigger high speed wind streams that presented many energetic events, especially during its declining phase (e.g.…”

mentioning

confidence: 97%

Investigation of the Relation between Space-Weather Parameters and Forbush Decreases Automatically Selected from Moscow and Apatity Cosmic Ray Stations during Solar Cycle 23

Alhassan,

Okike,

Chukwude

2021

Preprint

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“…There are two main kinds of IPDs-sporadic and recurrent. Sporadic IPDs are caused by coronal mass ejections (CMEs) and their IP version-interplanetary coronal mass ejections (ICMEs) while recurrent IPDs are associated with heliospheric current sheet and high-speed plasma flows from coronal holes (CHs) which co-rotate with the Sun (Belov et al 2001(Belov et al , 2014Alhassan et al 2021b). FDs from CHs are known to have small magnitudes while those caused by CMEs have large magnitude signatures (Lockwood 1971;Belov et al 2009;Melkumyan et al 2019).…”

Section: Introductionmentioning

confidence: 99%

Testing the empirical relationship between Forbush decreases and cosmic ray diurnal anisotropy

Alhassan,

Okike,

Chukwude

2022

Preprint

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The abrupt aperiodic modulation of cosmic ray (CR) flux intensity, often referred to as Forbush decrease (FD), plays a significant role in our understanding of the Sun-Earth electrodynamics. Accurate and precise determination of FD magnitude and timing are among the intractable problems in FD-based analysis. FD identification is complicated by CR diurnal anisotropy. CR anisotropy can increase or reduce the number and amplitude of FDs. It is therefore important to remove its contributions from CR raw data before FD identification.Recently, an attempt was made, using a combination of Fourier transformed technique and FD-location machine to address this. Thus, two FD catalogs and amplitude diurnal variation (ADV) were calculated from filtered (FD1 and ADV) and raw (FD2) CR data. In the current work, we test the empirical relationship between FD1, FD2, ADV and solar-geophysical characteristics. Our analysis shows that two types of magnetic fields-interplanetary (IMF) and geomagnetic (Dst) govern the evolution of CR flux intensity reductions.

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“…Though FDs and GLEs are interesting counterparts in the CR flux variations, a review of the available literature on the CR intensity variability shows that scientists investigating FDs have made significant advancements while those analyzing GLEs have recorded comparatively less progress. However, both manual and automated detection of GLEs remains a challenge in the field, for example, timing and amplitude estimations of FD events have been successfully automated (see Okike 2020a; Okike & Alhassan 2022;Alhassan et al 2022b, and the references therein). While GLE event simultaneity has yet to be tested in detail, Forbush event global simultaneity has been the focus of several publications (Oh et al 2008;Oh & Yi 2009;Okike & Collier 2011;Oh & Yi 2012;Lee et al 2015).…”

Section: Introductionmentioning

confidence: 99%

“…This is most likely the reason why such NMs record lower intensity compared to their counterparts at the same latitude and longitude. The above number of competing factors makes the analysis of CR intensity variation (e.g., GLEs and FDs) an interesting subject with numerous submissions (Simpson 1954;Lockwood & Webber 1969;Stroker 1994;Belov 2009; Usoskin et al 2011a;Belov et al 2018;Miroshnichenko 2018;Okike 2019b;Okike & Umahi 2019a;Okike 2019a) and many unexploited possibilities (see Okike 2021;Okike et al 2021bOkike et al , 2021aAlhassan et al 2021Alhassan et al , 2022aAlhassan et al , 2022bOkike & Alhassan 2022).…”

Section: Introductionmentioning

confidence: 99%

Analysis of Ground Level Enhancement Events of 1989 September 29; 2001 April 15 and 2005 January 20

UGWOKE¹,

Ubachukwu²,

Urama³

et al. 2022

Res. Astron. Astrophys.

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We present the results of analyses of the ground level enhancements (GLEs) of cosmic ray (CR) events of 29 September 1989; 15 April 2001 and 20 January 2005. This involve examination of hourly raw CR counts of an array of neutron monitors (NMs) spread across different geographi- cal latitudes and longitudes. Using awk script and computer codes implemented in R-software, the pressure corrected raw data plots of the NMs were grouped into low-, mid-, and, high-latitudes. The results show both similarities and differences in the structural patterns of the GLE signals. In an attempt to explain why the CR count during the decay phase of GLEs is always higher than the count before peak, we interpreted all counts prior to the peak as coming from direct solar neutrons and those in the decay phase including the peak as coming from secondary CR neutrons generated by the interactions of primary CRs with the atoms and molecules in the atmosphere. We identified NMs that detected these primary neutrons and found that they are close in longitudes. Previous au- thors seemingly identified these two species as impulsive and gradual events. Although there are a number of unexplained manifestations of GLE signals, some of the results suggest that geomagnetic rigidity effectively determines the intensity of CRs at low- and mid-latitudes. Its impact is apparently insignificant in high-latitude regions. Nevertheless, the results presented should be validated before making any firm statements. Principally, the contributions of the ever-present and intractable CR diurnal anisotropies to GLE signals should be accounted for in future work.

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Testing the simultaneity of Forbush decreases with algorithm-selected Forbush event catalogue

Cited by 8 publications

References 50 publications

Investigation of the Relation between Space-Weather Parameters and Forbush Decreases Automatically Selected from Moscow and Apatity Cosmic Ray Stations during Solar Cycle 23

Investigation of the Relation between Space-Weather Parameters and Forbush Decreases Automatically Selected from Moscow and Apatity Cosmic Ray Stations during Solar Cycle 23

Testing the empirical relationship between Forbush decreases and cosmic ray diurnal anisotropy

Analysis of Ground Level Enhancement Events of 1989 September 29; 2001 April 15 and 2005 January 20

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