Investigation of the cosmic ray ground level enhancements during solar cycle 23

Abstract During the solar maximum of 1989–91 an unprecedented sequence of 13 cosmic ray ground-level enhancements (GLEs) was observed by the world-wide neutron monitor network. Of particular interest were two GLEs observed by the Australian network. The 1989 September 29 event was the largest GLE in the space era while the October 22 GLE included an highly anisotropic precursor peak.Analysis of both these GLEs, taking into account disturbed geomagnetic conditions, shows that the particle arrivals at the earth were unusual. The September 29 GLE had significant particle propagation in the reverse direction and as the particle flux decreased following the peak the spectrum also softened. In contrast, the 1989 October 22 precursor exhibited extreme anisotropy while the particles involved in the main GLE showed a complex temporal structure possibly indicating multiple particle injection at the solar acceleration region.

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Properties of Ground Level Enhancement Events and the Associated Solar Eruptions During Solar Cycle 23

Space Science Reviews ◽

10.1007/s11214-012-9890-4 ◽

2012 ◽

Vol 171 (1-4) ◽

pp. 23-60 ◽

Cited By ~ 154

Author(s):

N. Gopalswamy ◽

H. Xie ◽

S. Yashiro ◽

S. Akiyama ◽

P. Mäkelä ◽

...

Keyword(s):

Solar Cycle ◽

Ground Level ◽

Ground Level Enhancement ◽

Solar Cycle 23 ◽

Solar Eruptions ◽

Ground Level Enhancement Events

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Evaluation of the short and intermediate term periodicities in cosmic ray intensity during solar cycle 23

Planetary and Space Science ◽

10.1016/j.pss.2010.04.005 ◽

2010 ◽

Vol 58 (7-8) ◽

pp. 1045-1049 ◽

Cited By ~ 15

Author(s):

Partha Chowdhury ◽

Manoranjan Khan ◽

P.C. Ray

Keyword(s):

Solar Cycle ◽

Cosmic Ray ◽

Cosmic Ray Intensity ◽

Solar Cycle 23

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Current status and possible extension of the global neutron monitor network

Journal of Space Weather and Space Climate ◽

10.1051/swsc/2020020 ◽

2020 ◽

Vol 10 ◽

pp. 17

Author(s):

Alexander Mishev ◽

Ilya Usoskin

Keyword(s):

Space Weather ◽

Neutron Monitor ◽

Cosmic Ray ◽

Ground Level ◽

Solar Proton ◽

Energetic Particles ◽

Solar Energetic Particles ◽

Current Status ◽

Flight Altitude ◽

Ground Level Enhancements

The global neutron monitor network has been successfully used over several decades to study cosmic ray variations and fluxes of energetic solar particles. Nowadays, it is used also for space weather purposes, e.g. alerts and assessment of the exposure to radiation. Here, we present the current status of the global neutron monitor network. We discuss the ability of the global neutron monitor network to study solar energetic particles, specifically during large ground level enhancements. We demonstrate as an example, the derived solar proton characteristics during ground level enhancements GLE #5 and the resulting effective dose over the globe at a typical commercial jet flight altitude of 40 kft (≈12,200 m) above sea level. We present a plan for improvement of space weather services and applications of the global neutron monitor network, specifically for studies related to solar energetic particles, namely an extension of the existing network with several new monitors. We discuss the ability of the optimized global neutron monitor network to study various populations of solar energetic particles and to provide reliable space weather services.

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