Incidence of Galactic Cosmic Ray Fluxes at Polar and Middle Latitude Regions

Abstract

Galactic Cosmic Rays (GCRs) incidence on the Earth’s near space environment is of major concern to humankind as it affects space weather. Upon entering Earth’s atmosphere, GCRs collide with atoms and molecules, and subsequently decay into muons and neutrinos which propagates through the earth’s surface. Theory and observations affirm that penetration of GCR from the Heliospheric Magnetic Field (HMF) to Earth’s atmosphere is leveraged by the earth’s magnetic force lines predominant at the polar regions. We used facilities at NASA Goddard Space Flight Center, Greenbelt, Maryland USA and analyzed GCR particles recorded by Neutron Monitors (NM) at Thule, Newark, Mc Murdo and South Pole hosted at Bartol Research Institute, University of Delaware, USA. Geomagnetic aa index was obtained from World Data Center for Geomagnetism, Kyoto, Japan. This work investigates the degree to which GCRs are modulated by Geomagnetic activities using Geomagnetic aa-index as a proxy to Geomagnetic activity. We studied GCRs incident at four Neutron Monitor (NM) Stations at; Thule in the Arctic region, McMurdo and South Pole in the Antarctica, and Newark in the Middle Latitude region across five solar cycles timescale (1964 to 2016). We performed Regression Analysis of GCR and Geomagnetic aa-index to observe the impact of geomagnetic activity on GCR flux at the designated regions of the Earth’s surface. Also, we carried out Time Series Analysis to observe GCR intensities at the four NM Stations for the period of study. Results from Regression Analysis revealed a weak association between GCR and Geomagnetic aa index, where Coefficient of Determination R2 is less than 0.5. The Time Series Analysis revealed highest fluxes of GCR at Thule, McMurdo and South Pole as compared to incidence at the Mid-Latitude region in Newark. Our model indicate that GCR fluxes are controlled by Geomagnetic Field structure.