STEREO-REleASE-Plus

STEREO REleASE+ combines the existing STEREO REleASE system (the relativistic electron module) with a novel radio module that qualifies type-III radio bursts as a precondition for a proton alert with the aim of reducing specific sources of false alarms. Type-III radio bursts, that are produced by electron beams accelerated in solar eruptive events travelling outward through the corona along open magnetic flux tubes, are used as an independent early evidence of particle escape from the Sun. The radio module automatically detects type-III radio bursts from STEREO-A SWAVES real-time radio spectrograms and determines a set of parameters that narrow down detected type-III radio bursts to those that have the potential of causing significant solar proton events at STEREO's current location. STEREO REleASE+ issues a proton alert only if the relativistic electron module creates an alert within the forecasting window set by the radio module. STEREO REleASE+ switches back to STEREO REleASE when data gaps in real-time radio data prevent proper identification of relevant type-III bursts.

The model uses real-time electron flux measurements from STEREO-A/SEPT and STEREO-A/HET, and radio measurements from STEREO-A/SWAVES.

The STEREO REleASE+ model produces two forecasts: one based on inputs from STEREO-A/SEPT and one based on STEREO-A/HET electron data for the proton energy channel 21–40 MeV. Forecasts are produced with a lead time of 30, 60, and 90 minutes. Based on these forecasts, the STEREO REleASE+ Alert module generates an alert based on the combination of the three most recent forecasts derived from STEREO-A/SEPT and STEREO-A/HET data. STEREO REleASE+ forecasts and alerts are issued only when electron data predicts proton increases during the forecasting window set by the radio module. If no real-time radio data are available, the system reverts to STEREO REleASE forecasts and alerts.

Version 1.0 was deployed on the CCMC CR system on February 4, 2026.

The following sentences and acknowledgements shall appear inline where the STEREO REleASE tool is presented and also when the STEREO REleASE tool is cited, mentioned as well as when the relevant results are presented, cited and mentioned:

"STEREO REleASE+ has been developed through funding from the National Aeronautics and Space Administration under grant agreement No. TXS0150641A (National Observatory of Athens) and No. TXS0150642 (Christian-Albrechts-Universität) and has been built in the open-source programming language PYTHON."

Moreover, the logo of the HESPERIA project as well as the logo of the National Aeronautics and Space Administration (NASA) will be displayed in due prominence in all these occasions in proper image file format to be provided by NOA.

Any commercial use of the STEREO REleASE+ SEP forecasting results by NASA/CCMC and/or migration of the STEREO REleASE model to an external system, i.e., other than NASA/CCMC, will be possible only after signature of a separate agreement between NASA/CCMC, the National Observatory of Athens and the Christian-Albrechts Universitaet zu Kiel, Germany.