Comparison of JPL and ESP Solar Proton Fluence Models Using the Background‐Subtracted RDSv2.0 Data Set

Abstract

AbstractHigh energy protons from solar energetic particle (SEP) events are a hazard to spacecraft systems and instruments. For interplanetary and geosynchronous‐Earth‐orbiting spacecraft, a mission's cumulative SEP fluence is an important consideration for hardware design. The total solar proton fluence for a mission can be dominated by a small number of very high‐fluence events. Because of the sporadic and unpredictable nature of these large events, data sets collected over multiple solar cycles are needed to construct a statistical model that can predict a mission's risk of seeing a given fluence exposure during its mission. Several statistical models have been developed, including the JPL model and the Emission of Solar Protons (ESP) model. The models produce somewhat different results, which could be due in part to the different data sets from which they were derived. To understand the sensitivity of predicted mission fluence to the choice of data set and to the statistical distribution to which that data set is fit, we present a comparison of the JPL and ESP cumulative fluence models as reformulated from the same SEP data set, a background‐subtracted version of the Reference Data Set Version 2.0 (RDSv2.0) based on data from IMP‐8 and GOES, covering 41 years of SEP events from 1974 to 2015 with proton energies between 5 and 289 MeV. The comparisons show that different modeling approaches can produce a factor of 2 or greater difference in the mission fluences even when the same data set is used for model development.