Authors: Adolfo Santa Fe Duenas (UNH), Noe Lugaz (UNH), Bin Zhuang (UNH), Nada Al-Haddad (UNH)

Energetic Storm Particles (ESPs) are frequently observed near interplanetary shocks driven by coronal mass ejections (CMEs), yet the conditions controlling their occurrence and intensity remain incompletely understood. While previous studies have often focused on individual events or single-spacecraft observations, multi-spacecraft measurements provide a unique opportunity to investigate how shock properties and observer geometry influence local particle acceleration.

In this study, we extend a previous case analysis to a multi-event investigation using observations from ACE, Wind, and STEREO-A. Starting from a catalog of CME-associated shock pairs observed by spacecraft at different heliolongitudes, we perform event-by-event analyses of magnetic field, plasma, and energetic particle measurements. Wind observations are used when available to improve temporal resolution in the characterization of shock crossings and ESP signatures. For each event, we derive shock parameters including compression ratios, shock normal orientation, shock speed, Alfvén Mach number, and shock geometry. We also identify ESP intervals and compute energetic particle spectral indices from proton measurements spanning approximately 0.2–1 MeV.

A systematic event validation procedure is being applied to identify a robust set of multi-spacecraft shock crossings suitable for statistical analysis. Preliminary inspection reveals substantial variability in particle responses between spacecraft, including cases where ESP enhancements differ significantly despite observations of the same large-scale CME-driven disturbance. Ongoing work focuses on establishing a high-quality event sample and investigating the relationship between ESP occurrence, shock properties, and spacecraft-to-source geometry.

This study provides a framework for evaluating the factors that govern ESP acceleration at interplanetary shocks and for quantifying the longitudinal variability of energetic particle events in the inner heliosphere.