Ensemble Forecasting of Major Solar Flares -- First Results

TL;DR

This paper introduces the first ensemble forecasting model for major solar flares, combining multiple probabilistic models to improve prediction accuracy using a data-driven weighting approach.

Contribution

It develops a novel ensemble prediction method for solar flares by linearly combining forecasts from multiple models and optimizing weights based on performance metrics.

Findings

Ensemble methods can enhance probabilistic and categorical flare predictions.

Optimal decision thresholds differ for M-class and X-class flares.

Including NOAA human-adjusted probabilities improves ensemble performance.

Abstract

We present the results from the first ensemble prediction model for major solar flares (M and X classes). The primary aim of this investigation is to explore the construction of an ensemble for an initial prototyping of this new concept. Using the probabilistic forecasts from three models hosted at the Community Coordinated Modeling Center (NASA-GSFC) and the NOAA forecasts, we developed an ensemble forecast by linearly combining the flaring probabilities from all four methods. Performance-based combination weights were calculated using a Monte-Carlo-type algorithm that applies a decision threshold $P_{th}$ to the combined probabilities and maximizing the Heidke Skill Score (HSS). Using the data for 13 recent solar active regions between years 2012 - 2014, we found that linear combination methods can improve the overall probabilistic prediction and improve the categorical prediction for certain values of decision thresholds. Combination weights vary with the applied threshold and none of the tested individual forecasting models seem to provide more accurate predictions than the others for all values of $P_{th}$. According to the maximum values of HSS, a performance-based weights calculated by averaging over the sample, performed similarly to a equally weighted model. The values $P_{th}$ for which the ensemble forecast performs the best are 25 \% for M-class flares and 15 \% for X-class flares. When the human-adjusted probabilities from NOAA are excluded from the ensemble, the ensemble performance in terms of the Heidke score, is reduced.