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