Abstract
Real-time estimation of cosmic-ray fluxes on satellite orbits is one of the greatest challenges in space weather research. Therefore, we develop a system for nowcasting and forecasting the galactic cosmic ray (GCR) and solar energetic particle (SEP) fluxes at any location in the magnetosphere and ionosphere during ground-level enhancement (GLE) events. It is an extended version of the WArning System for AVIation Exposure to SEP (WASAVIES), which can determine event profiles by using real-time data of the count rates of several neutron monitors (NMs) at the ground level and high-energy proton fluxes observed by Geostationary Operational Environmental Satellites (GOES) satellites. The extended version, called WASAVIES-EO, can calculate the GCR and SEP fluxes outside a satellite based on its two-line element (TLE) data. Moreover, organ absorbed-dose and dose-equivalent rates of astronauts in the International Space Station (ISS) can be estimated using the system, considering its shielding effect. The accuracy of WASAVIES-EO was validated based on the dose rates measured in ISS, as well as based on high-energy proton fluxes observed by POES satellites during large GLEs that have occurred in the 21st century. Agreement between the nowcast and forecast dose rates in ISS, especially in terms of their temporal structures, indicates the usefulness of the developed system for future mission operations.
Highlights
Estimation of the fluxes of high-energy particles in the Earth’s magnetosphere is very important for designing space missions because they can adversely affect the health of astronauts and cause single-event upsets of semi-conductor devices used in satellites
The present study focuses on describing the extended part of the calculation procedures, together with its validation results, based on the experimental data measured by International Space Station (ISS) and Polar Orbiting Environmental Satellites (POES) during large ground-level enhancement (GLE) that have occurred in the 21st century
For reproducing the high-energy proton fluxes measured by Medium Energy Proton and Electron Detector (MEPED) loaded on POES, we integrated the calculated proton fluxes on their orbits, UGCR;Sout and USEP;Sout, for energies higher than 100 MeV
Summary
Estimation of the fluxes of high-energy particles in the Earth’s magnetosphere is very important for designing space missions because they can adversely affect the health of astronauts and cause single-event upsets of semi-conductor devices used in satellites. An active dosimeter-based method for estimating astronaut acute radiation risk during SPE in real time was recently proposed (Mertens et al, 2018) With these situations in mind, we set out to develop a new computational method that can nowcast and forecast SEP fluxes at any location in the magnetosphere and ionosphere during a large SPE associated with a ground-level enhancement (GLE). It is an extended version of the WArning System for AVIation Exposure to SEP (WASAVIES) (Kataoka et al, 2014; Kataoka et al, 2018; Sato et al, 2018b), which can nowcast and forecast radiation doses in the atmosphere by using real-time data of the count rates of several neutron monitors (NMs) at the ground level and high-energy proton fluxes observed by Geostationary Operational Environmental Satellites (GOES). The present study focuses on describing the extended part of the calculation procedures, together with its validation results, based on the experimental data measured by ISS and Polar Orbiting Environmental Satellites (POES) during large GLEs that have occurred in the 21st century
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