Ensemble Prediction of a Halo Coronal Mass Ejection Using Heliospheric Imagers

Area of Science:

• Space Physics
• Heliophysics
• Solar Eruptions

Background:

• The Solar Terrestrial Relations Observatory (STEREO) and its heliospheric imagers (HIs) enable enhanced understanding of coronal mass ejection (CME) interplanetary propagation.
• HI-based methods can forecast CME arrival times and speeds, tracing their paths up to and beyond 1 AU.

Purpose of the Study:

• To utilize the ELEvoHI model with an ensemble approach for CME arrival prediction and uncertainty quantification.
• To analyze a specific CME event from November 3, 2010, using 339 model runs and comparing with in situ measurements.

Main Methods:

• Employed the ELEvoHI model for CME arrival prediction.
• Utilized an ensemble approach with 339 model runs to derive uncertainties in arrival time and impact speed.
• Analyzed frequency distributions of ELEvoHI output parameters (drag parameter, solar wind speed, initial distance, speed) to identify optimal predictions.

Main Results:

• A promising approach using frequency distributions of ELEvoHI outputs yielded predictions with smaller errors.
• Restricting the ensemble to runs with the most frequent parameter values reduced the mean absolute arrival time error at 1 AU from 3.5 ± 2.6 hr to 1.6 ± 1.1 hr.
• Remote HI observations from STEREO-B, showing a halo CME, were comparable to an L1 observer viewing an Earth-directed CME.

Conclusions:

• The L1 vantage point may be sufficient for observing Earth-directed CMEs with heliospheric imagers.
• Ensemble modeling with ELEvoHI shows potential for operational CME arrival time predictions.
• The study highlights the effectiveness of refining ensemble members based on parameter frequency distributions.