Analysis of sub-GLE and GLE events using NM data : space weather applications

Abstract

Detailed study of solar energetic particle events is important to understand their acceleration and propagation in the interplanetary space and allows one to model various processes related to space weather and space climate e.g. radiation environment at flight altitudes and atmospheric ionization. A special class of events, called ground level enhancements, registered by ground based detectors, can dramatically change the radiation environment in the Earth’s atmosphere. New recently installed high-altitude polar neutron monitors NMs, namely DOMC/B and historically installed South Pole, have made the worldwide neutron monitor network more sensitive to strong solar energetic particle events, registered at ground level. The two high-altitude polar stations are able to detect lower energy events, which most likely would not be registered by the other (near sea level) neutron monitor stations. Here, using the worldwide neutron monitor database (NMDB) records and an optimization procedure combined with simulations, we assess the spectral and angular characteristics of a new class of events sub-GLEs. With the estimated spectral characteristics as an input, we evaluate the effective dose rate in polar and sub-polar regions at typical commercial flight altitude during such events as well as during GLEs.