Abstract
Radiation exposure due to cosmic rays, specifically at cruising aviation altitudes, is an important topic in the field of space weather. While the effect of galactic cosmic rays can be easily assessed on the basis of recent models, estimate of the dose rate during strong solar particle events is rather complicated and time consuming. Here we compute the maximum effective dose rates at a typical commercial flight altitude of 35 kft (≈11 000 m above sea level) during ground level enhancement events, where the necessary information, namely derived energy/rigidity spectra of solar energetic particles, is available. The computations are carried out using different reconstructions of the solar proton spectra, available in bibliographic sources, leading to multiple results for some events. The computations were performed employing a recent model for effective dose and/or ambient dose equivalent due to cosmic ray particles. A conservative approach for the computation was assumed. A highly significant correlation between the maximum effective dose rate and peak NM count rate increase during ground level enhancement events is derived. Hence, we propose to use the peak NM count rate increase as a proxy in order to assess the peak effective dose rate at flight altitude during strong solar particle events using the real time records of the worldwide global neutron monitor network.
Highlights
According to the generally accepted definition, space weather concerns dynamic conditions on the Sun and solar wind resulting in changes in the Earth’s radiation environment, magnetosphere and ionosphere, which eventually can compromise the performance of spacecraft and ground-based systems and can endanger human health (e.g. Baker, 1998; Lilensten & Bornarel, 2009).Active processes on the Sun, such as Coronal Mass Ejections (CMEs), solar flares and high-speed solar wind streams may lead to sequence(s) of disturbances in the Earth’s magnetosphere and atmosphere, occasionally even impacting the ground level as geomagnetic storms and enhancements of relativistic electron populations in outer radiation belts
As a result we propose a convenient proxy for the maximum effective dose rate due to SEPs at commercial aviation altitudes during GLEs, which is suitable for operational purposes
On the basis of the SEP rigidity spectra derived from NM records, the maximum effective dose rates at the aviation altitude of 35 kft during these events was calculated using a recently proposed model
Summary
According to the generally accepted definition, space weather concerns dynamic conditions on the Sun and solar wind resulting in changes in the Earth’s radiation environment, magnetosphere and ionosphere, which eventually can compromise the performance of spacecraft and ground-based systems and can endanger human health (e.g. Baker, 1998; Lilensten & Bornarel, 2009). While less energetic SEPs are fully absorbed in the atmosphere, more energetic ones can initiate an atmospheric cascade, to Galactic Cosmic Rays (GCRs), whose secondaries eventually reach the ground, leading to an enhancement of count rates of ground based detectors, in particular Neutron Monitors (NMs) This special class of SEP events is known as Ground Level Enhancements (GLEs). The radiation environment, aircrew exposure depends on geographic position, altitude and solar activity (Spurny et al, 1996, 2003; Shea & Smart, 2000) and is mainly defined by GCRs, which originate from the Galaxy and consist mostly of protons and a-particles with small abundance of heavier nuclei High energy SEP events may enhance the radiation exposure in the atmosphere at commercial flight altitudes, in the polar regions As a result we propose a convenient proxy for the maximum effective dose rate due to SEPs at commercial aviation altitudes during GLEs, which is suitable for operational purposes
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