Forecasting Solar Energetic Proton events (E > 100 MeV)

A solar radiation storm occurs when a major event on the Sun or in the interplanetary medium accelerates protons toward Earth. These events have a significant effect on satellites and humans. In the atmosphere, they interact to produce penetrating neutrons that irradiate passengers and flight crews in commercial aircraft flying polar routes. In space, protons affect electronic circuits, solar cells and the mirrored surfaces of satellites and spacecraft, and they may penetrate the space suits of astronauts aboard the International Space Station. UMASEP predicts events of energies greater than 10 MeV (Núñez, 2011) and 100 MeV (Núñez, 2015). The real-time predictions of these SEP events may be consulted in http://spaceweather.uma.es/forecastpanel.htm.

This page summarizes the performance of the UMASEP v1.2 for predicting SEP events with E > 100 MeV from historical data of solar cycles 23 and 24. For these events UMASEP predicts the time interval within which the integral proton flux is expected to meet or surpass the Space Weather Prediction Center threshold of J (E > 100 MeV) = 1 pfu and the intensity of the first hours of well connected SEP events. This forecaster analyzes flare and near Earth space environment data observed by the GOES satellites. It analyzes soft X-ray fluxes and the differential proton fluxes that corresponds to the channels P6 to P11. The purpose of the > 100 MeV SEP forecast model is to identify precursors of well-connected events by empirically estimating the magnetic connectivity from the associated CME/flare process zone to the near Earth environment and identifying the flare temporally associated with the phenomenon, by using the same approach described in  (Núñez, 2015) and summarized here.

Figure 1 shows two forecast images that an operator would have seen if the UMASEP v1.2 forecaster had processed the real-time GOES data during March 7th, 2012. The small image at the left of Figure 1 shows the forecast (before the occurrence of the event), which also presents some inferences about the situation (the time and active region of the associated flare and the energy channels that are associated with event). The small image at the top right shows the forecast image several hours after the flux surpasses the hazardous threshold of 1 pfu. The image at the bottom right of Figure 1 shows the neutron data at ground level, detected by the Neutron Monitor (www.nmdb.eu) during this event, showing that the predicted event was not a ground level event (GLE). Figure 2 shows the UMASEP's forecasts results for the period January 17-20, 2005, when two GLE event took place. Figure 3 shows some images generated by UMASEP for predicting >100 MeV events. Most of these images show predictions of SEP events which are also GLE events. Figure 4 shows the counters for calculating the probability of detection and the false alarm ratio from GOES flux data files of solar cycles 23 and 24.

Figure 1. UMASEP's forecast result from historical data of March 7th, 2012. UMASEP issues the forecast of a >100MeV SEP event with the GOES files with flux data up to 3:20 (UTC). The integral proton flux (E >100 MeV) surpassed the SEP threshold (1 pfu) at 4:05. The warning time for this event was 45 mins.

 

Figure 2. UMASEP's forecast result from historical data from January 17th to January 20th, 2005. During this period, two ground level events (GLE) took place. The Neutron Monitor detected the second event in real-time as it is indicated in the small chart in the middle of the figure. By processing historical data of GOES satellites, UMASEP could predict both GLE events. The warning time was 1 h 45 min for the first event was and 5 minutes for the second event.

 

SEP (E >100 MeV) January 27, 2012 Warning time: 20 min	SEP (E > 100 MeV) April 2, 2001 Warning time: 1h 20 min	SEP (E > 100 MeV) December 7, 2006 Warning time: 4 h 55 min	GLE 71 /  SEP (E > 100 MeV) May 17 2012 Warning time: 5 min
GLE 69 /  SEP (E >100 MeV) January 20, 2005 Warning time: 5 min	GLE 68 /  SEP (E > 100 MeV) January 17, 2005 Warning time: 1 h 45 min	GLE 65 /  SEP (E > 100 MeV) October 28, 2003 Warning time 20 min	GLE64 /  SEP (E > 100 MeV) August 24, 2002 Warning time 5 min
GLE 61 /  SEP (E > 100 MeV) April   18, 2001 Missed event	GLE 60 /  SEP (E > 100 MeV) April 15, 2001 Warning time: 10 min	GLE 58 /  SEP (E > 100 MeV) August 24, 1998 Warning time: 20 min	GLE 56 /  SEP (E > 100 MeV) May 2, 98 Missed event

Figure 3. UMASEP's forecast results from historical data. The first three images are forecasts of events that are not Ground Level Events. The rest images are forecasts of very energetic events associated to GLE events.

 

Fig. 4. This figure shows several counters for the period since January 1994 to September 2013: number of correct SEP forecast, number of missed SEPs and the number of false forecasts. These counters show that the probability of detection (POD) is 80.85% (38/47) and the false alarm rate is 29.62% (16/55) .

 

Validation results

For the SEP events from January 1994 to September, 2013, UMASEP has a probability of detection (POD) of >100 MeV events of 80.85% (38/47) and a false alarm ratio (FAR) of 29.62% (16/54). Regarding the correct forecasts, UMASEP anticipated the >100 MeV events in 1 h 6 min on average. Figure 4 shows the counters for calculating the POD and the FAR of UMASEP predicting >100 MeV events for the period January 1994 - September 2013.

 

References
 

Núñez, M (2015), Real-time prediction of the occurrence and intensity of the first hours of > 100 MeV solar energetic proton events, Space Weather, 13, doi:10.1002/2015SW001256.
Núñez, M. (2011), Predicting solar energetic proton events (E > 10 MeV), Space Weather, 9, S07003, doi:10.1029/2010SW000640. Preprint (PDF)

 

Contact:

  Prof. Dr. Marlon Núñez

 

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