Segmental interpolating spectra for solar particle events and in situ validation

Abstract

It is a delicate task to accurately assess the impact of solar particle events (SPEs) on future long-duration human exploration missions. In the past, researchers have used several functional forms to fit satellite data for radiation exposure estimation. In this work we present a segmental power law interpolating algorithm to stream satellite data and get time series of proton spectra, which can be used to derive dosimetric quantities for any short period during which a single SPE or multiple SPEs occur. Directly using the corrected High Energy Proton and Alpha Detector fluxes of GOES, this method interpolates the intensity spectrum of a typical SPE to hundreds of MeV and extrapolates to the GeV level as long as sufficient particles are recorded in the high-energy sensors. The high-energy branch of the May 2012 SPE is consistent with the Band functional fitting, which is calibrated with ground level measurement. Modeling simulations indicate that the input spectrum of an SPE beyond 100 MeV is the major contributor for dose estimation behind the normal shielding thickness of spacecraft. Applying this method to the three SPEs that occurred in 2012 generates results consistent with two sets of in situ measurements, demonstrating that this approach could be a way to perform real-time dose estimation. This work also indicates that the galactic cosmic ray dose rate is important for accurately modeling the temporal profile of radiation exposure during an SPE.