Calculating Three-dimensional Interplanetary Shock Velocity and Normals via Triple-spacecraft XGBoost Optimization

Fast interplanetary shocks and their solar drivers may disrupt satellite functionality and cause severe geomagnetic consequences. In light of this relevance, we develop an XGBoost orbital artifact correction algorithm that enables us to use simultaneous measurements from ACE, Wind, and DSCOVR to produce a large-scale, three-dimensional, and observationally consistent shock analysis at L1. Over 7 yr of data, we apply logistic regressions to identify shocks over a wide range of orbital configurations and produce a novel L1 shock list. We perform a statistical analysis of these events, including their shock-normal distributions, solar drivers, and coherence lengths. Most shocks are constrained within some angle of the Earth–Sun line, and we clearly observe the poleward deflection of reverse shocks driven by stream interaction regions. Finally, while shock coherence generally falls off over 90 Re, it is strongly dependent on shock speed, with coherence lengths of faster shocks being over 3× greater than for slower events. Since the evolution of solar wind structures determines the ideal physical conditions for cross-satellite comparisons, analyzing solar wind coherence is critical to instrument calibration and validation. Thus, our coherence analysis and novel shock list will inform the identification of suitable conditions for instrument calibration validation of future missions such as the Space Weather Follow On L1 (SWFO-L1).