A Comparison of MAVEN SIR Observations With the Stationary WSA-ENLIL Solar Wind Model

Abstract

Predicting times of arrival and properties of space weather events, such as coronal mass ejections and stream interaction regions (SIRs), has become an important focus of the space physics community within recent years. Extensive efforts have been undertaken to model these space weather events throughout the heliosphere in order to better understand their properties and predict how and when they will impact planetary environments. In this study, we compare in situ solar wind parameters during SIRs measured by the Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft to parameters generated by the Wang-Sheeley-Arge (WSA)-ENLIL stationary solar wind model. We compare times of arrival, end times, event duration, solar wind parameters, and magnetic compression ratios as measured by MAVEN versus WSA-ENLIL using a previously compiled 9-year catalog of SIR observations. We find that WSA-ENLIL, on average, predicts earlier times of arrival and longer duration SIRs than what is observed by MAVEN. We examine how in situ solar wind parameters compare to those predicted by WSA-ENLIL and find that solar wind proton density and magnetic field magnitude are slightly underpredicted by the model, while solar wind speed is well predicted. We also find that the magnetic compression ratio predicted by WSA-ENLIL is higher than MAVEN by an average of ∼ 26%. We examine the effects of planetary geometry on the modeling outputs and find that certain parameters are more adversely impacted than others depending on the alignment of Earth and Mars.