Introduction of UMASEP

Solar energetic particles (SEPs) are sometimes energetic enough and the flux is high enough to cause air showers in the stratosphere and in the troposphere, which are an important ionization source in the atmosphere.  >500 MeV solar protons are so energetic that they usually have effects on the ground, producing what is called a Ground Level Event (GLE).

One to the goals of the HESPERIA project is the development of a predictor of >500 SEP proton events at the near-earth (e.g. at geostationary orbit).  In order to predict these events, the UMASEP scheme [Núñez, 2011, 2015] will be used. UMASEP makes a lag-correlation of solar electromagnetic (EM) flux with the particle flux at near-earth.  If the correlation is high, the model infers that there is a magnetic connection through which particles are arriving. If, additionally, the intensity of the flux of the associated solar event is also high, then the UMASEP scheme issues a SEP prediction.

In the case of the prediction of >500 MeV SEP events, the implemented system, called UMASEP-500, correlates X-ray flux with each of the differential proton fluxes measured by the GOES satellites, and with each of the neutron density fluxes collected by neutron monitor stations around the world. When the correlation estimation surpasses a threshold, and the associated flare is greater than a specific X-ray peak flux, a  >500 MeV SEP forecast is issued.

Description of plot

This figure shows the output image of the >500 MeV SEP predictor. This image presents three time series:

• The upper time series of this image shows the recent and the predicted >500 MeV proton flux. The current flux is at the left of the label "Now". The predicted >500 MeV flux is presented at the right of this label. The predicted intensity of the first 1 hour of the expected event are indicated by colors, which corresponds to certain intensity levels (in pfu) according to the vertical bar at the right.
• The middle time series in the left image of the forecast output shows recent solar activity in terms of soft X-rays.
• The time series at the bottom of the forecast output presents the empirically-estimated level of magnetic connectivity of the observed  >500 MeV solar particles to Earth.

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