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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Impacts on Cosmic-Ray Intensity Observed During Geomagnetic Disturbances

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Author(s):
Adhikari, Binod [1, 2] ; Sapkota, Nirakar [1] ; Baruwal, Prashrit [3] ; Chapagain, Narayan P. [2] ; Braga, Carlos Roberto [4]
Total Authors: 5
Affiliation:
[1] St Xaviers Coll, Dept Phys, Kathmandu - Nepal
[2] Tribhuvan Univ, Dept Phys, Patan M Campus, Lalitpur - Nepal
[3] Tribhuvan Univ, Dept Phys, Amrit Sci Campus, Kathmandu - Nepal
[4] Natl Inst Space Res INPE, BR-12227010 Sao Jose Dos Campos, SP - Brazil
Total Affiliations: 4
Document type: Journal article
Source: SOLAR PHYSICS; v. 292, n. 10 OCT 2017.
Web of Science Citations: 2
Abstract

Geomagnetic disturbances are the results of interplanetary causes such as highspeed streamers (HSSs), interplanetary coronal mass ejections (ICMEs), corotating interaction regions (CIRs), and magnetic clouds. During different forms of geomagnetic disturbances, we observed changes in the count rate at neutron monitors that are kept at various locations. We studied the count rates measured by neutron monitors at four stations at various latitudes during different categories of geomagnetic events and compared them. We analysed five events: a geomagnetically quiet event, a non-storm high-intensity long-duration continuous AE activity (HILDCAA) event, a storm-preceded HILDCAA event, a geomagnetic substorm event, and a geomagnetic moderate storm event. We based our analysis on geomagnetic indices, solar wind parameters, and interplanetary magnetic field (IMF) parameters. We found that the strength of the modulation was least during the quiet event and highest during the storm-preceded HILDCAA. By analysing the cause of these geomagnetic disturbances, we related each decrease in the neutron monitor data with the corresponding solar cause. For the ICME-driven storm, we observed a decrease in neutron monitor data ranging from 6% to 12% in all stations. On the other hand, we observed a decrease ranging from 2% to 5% for the HSS-driven storm. For the non-storm HILDCAA, we observed a decrease in neutron monitor data of about 1% to 1.5%. For the quiet event, the neutron monitor data fluctuated such that there was no overall decrease in all stations. (AU)

FAPESP's process: 13/02712-8 - Study of interplanetary magnetic structures using cosmic ray data from the global muon detector network
Grantee:Carlos Roberto Braga
Support Opportunities: Scholarships abroad - Research Internship - Doctorate
FAPESP's process: 14/24711-6 - Study of coronal mass ejections and its corresponding interplanetary structures near the Earth
Grantee:Carlos Roberto Braga
Support Opportunities: Scholarships in Brazil - Post-Doctoral
FAPESP's process: 12/05436-9 - Study of coronal mass ejections and their interplanetary counterparts combining observations of ground cosmic ray detectors and coronagraphs
Grantee:Carlos Roberto Braga
Support Opportunities: Scholarships in Brazil - Doctorate