Analysis of diurnal cosmic-ray variations as observed by polar NMs
Abstract
Galactic cosmic rays (GCRs) show a low local anisotropy perceived as a diurnal variability of neutron-monitor (NM) count rates. The NMs have different abilities of observations of the GCR diurnal variation, because their asymptotic directions are spatially diverse at a large extent. We demonstrate that there is one NM at Dome C (DOMC) which does not observe diurnal variability. Compared to other polar NMs, for which the diurnal variation amplitudes span between 0.16 to 0.4%, it is very small (0.03%) for DOMC. It is due to the narrow asymptotic cone of the DOMC NM, directed practically in the polar direction with geographic latitude over 75 degrees south. Hence, DOMC NM is the uniquely located NM, which accepts cosmic rays from the off-equatorial and off-ecliptic plane. This is of special interest for comprehensive studies of cosmic-ray transport in the Earth vicinity, particularly for anisotropic solar energetic particle events.
- Publication:
-
44th COSPAR Scientific Assembly. Held 16-24 July
- Pub Date:
- July 2022
- Bibcode:
- 2022cosp...44.1067G