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

Sarah Henderson; Rachael Filwett; Sophia Owen; Jasper Halekas; Jacob Gruesbeck

doi:10.1029/2025JA034641

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 ∼${\sim} $ 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. Plain Language Summary Predicting times of arrival and properties of space weather events has become an important focus of the space physics community within recent years. Understanding how accurately models can predict properties of space weather events will help us in future endeavors, including Martian exploration. In this study, we compare spacecraft measurements of stream interaction regions (SIRs) at Mars with model results. We find that, on average, the model predicts an early arrival of SIRs at Mars, as well as SIRs that last longer than what we observe. We also compare solar wind parameters measured by the Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft and predicted by the Wang‐Sheeley‐Arge (WSA)‐ENLIL model. We find that WSA‐ENLIL predicts lower solar wind densities and magnetic field magnitude than what is measured at MAVEN, but the solar wind speed is predicted well for most events. We determine how much the magnetic field changes within each SIR and find that the model predicts a larger change than what is observed at MAVEN. We also find that how Mars and Earth are aligned slightly impacts WSA‐ENLIL's ability to predict certain parameters. Key Points WSA‐ENLIL predicts SIRs arrive earlier and last longer compared to in situ measurements made by MAVEN SIR speed is well predicted by WSA‐ENLIL, while density and magnetic field magnitude are smaller than in situ measurements from MAVEN In situ magnetic compression ratios measured at MAVEN are, on average, smaller than those predicted by WSA‐ENLIL

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

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