Exploring the potential of microwave diagnostics in SEP forecasting: The occurrence of SEP events

Abstract

Solar energetic particles (SEPs), especially protons and heavy ions, may be a space-weather hazard when they impact spacecraft and the terrestrial atmosphere. Forecasting schemes have been developed, which use earlier signatures of particle acceleration to predict the arrival of solar protons and ions in the space environment of the Earth. The UMASEP (University of MAlaga Solar particle Event Predictor) scheme forecasts the occurrence and the importance of an SEP event based on combined observations of soft X-rays, their time derivative and protons above 10 MeV at geosynchronous orbit. We explore the possibility to replace the derivative of the soft X-ray time history with the microwave time history in the UMASEP scheme. To this end we construct a continuous time series of observations for a 13-month period from December 2011 to December 2012 at two microwave frequencies, 4.995 and 8.8 GHz, using data from the four Radio Solar Telescope Network (RSTN) patrol stations of the US Air Force, and feed this time series to the UMASEP prediction scheme. During the selected period the Geostationary Operational Environmental Satellites (GOES) detected nine SEP events related to activity in the western solar hemisphere. We show that the SEP forecasting using microwaves has the same probability of detection as the method using soft X-rays, but no false alarm in the considered period, and a slightly increased warning time. A detailed analysis of the missed events is presented. We conclude that microwave patrol observations improve SEP forecasting schemes that employ soft X-rays. High-quality microwave data available in real time appear as a significant addition to our ability to predict SEP occurrence.

Predicting well-connected SEP events from observations of solar soft X-rays and near-relativistic electrons

“…If the solar EM peak flux of the associated flare is greater than a certain threshold, an SEP event prediction is triggered. Regarding solar EM data, the UMASEP's WCP scheme has been used with SXR flux (Núñez 2011(Núñez , 2015Núñez et al 2017Núñez et al , 2018, and microwave (MW) flux density at 5 and 9 GHz (Zucca et al 2017). Regarding in situ particle data, the WCP scheme has been used with proton data only; however, in this paper we evaluate for the first time the use of electron data in this scheme.…”

Onsets of Solar Proton Events in Satellite and Ground Level Observations: A Comparison

“…(In this paper we follow the terminology of the National Oceanic and Atmospheric Administration (NOAA) Space Weather Prediction Center (SWPC), which sometimes differs from that of referenced papers. Warnings are based on predictions—in the case of solar proton fluxes, based in part on soft X‐ray solar flare observations (e.g., Balch, ; Kahler et al, , ; Núñez, , ) or solar microwave radio bursts (e.g., Zucca et al, ), while alerts are based on observations of proton event onsets.) SPE alerts issued by SWPC are based on observations by the primary NOAA Geostationary Operational Environmental Satellite (GOES) for solar protons.…”

Diagnostic Analysis of the Solar Proton Flares of September 2017 by Their Radio Bursts

“…It is based on the fact that the flare electromagnetic radiation comes to the Earth for tens of minutes -hours earlier than, for example, protons with E > 10 MeV. This allows by the observed soft X-ray emission or radio bursts from an already occurring flare to determine in advance whether it will be accompanied by a noticeable SEP and to estimate its expected parameters [Belov et al, 2005;Kahler et al, 2007;Nûñez M., 2011;Anastasiadis et al, 2017;Zucca et al, 2017]. The original technique for the proton flare diagnostics by the accompanying radio bursts, allowing to estimate the intensity of the proton flux, its time parameters and the energy spectrum, taking into account the heliolongitude of the flare and the escape conditions of particles into the interplanetary space, was developed in IZMIRAN in 1970-1980s [Akinyan et al , 1977, 1978, 1980a,b, 1981.…”