Verification of operational solar flare forecast: Case of Regional Warning Center Japan

TL;DR

This study evaluates the performance of RWC Japan's 16-year operational solar flare forecasts using scalar verification measures, comparing them with persistence and recurrence methods, and proposes a new verification strategy.

Contribution

It introduces a comprehensive verification approach for operational solar flare forecasts, including scalar measures and stratified analysis by solar activity levels.

Findings

No significant performance difference between RWC Japan and persistence forecasts.

Slightly significant differences found for some event definitions.

Proposes a scalar verification measure and strategy for operational forecast assessment.

Abstract

In this article, we discuss a verification study of an operational solar flare forecast in the Regional Warning Center (RWC) Japan. The RWC Japan has been issuing four-categorical deterministic solar flare forecasts for a long time. In this forecast verification study, we used solar flare forecast data accumulated over 16 years (from 2000 to 2015). We compiled the forecast data together with solar flare data obtained with the Geostationary Operational Environmental Satellites (GOES). Using the compiled data sets, we estimated some conventional scalar verification measures with 95% confidence intervals. We also estimated a multi-categorical scalar verification measure. These scalar verification measures were compared with those obtained by the persistence method and recurrence method. As solar activity varied during the 16 years, we also applied verification analyses to four subsets of forecast-observation pair data with different solar activity levels. We cannot conclude definitely that there are significant performance difference between the forecasts of RWC Japan and the persistence method, although a slightly significant difference is found for some event definitions. We propose to use a scalar verification measure to assess the judgment skill of the operational solar flare forecast. Finally, we propose a verification strategy for deterministic operational solar flare forecasting.