1. EGU General Assembly 2016
Contact:
Dr. Johannes Labrenz
Extraterrestrische Physik
Institut für Experimentelle und Angewandte Physik
Christian Albrechts-Universität zu Kiel
Leibnizstraße 11, 24118
Tel.:
Near realtime forecasting of MeV protons on the basis of sub relativistic electrons
J. Labrenz¹, B. Heber¹, P. Kühl1, C. Sarlanis2, O. Malandraki3, A. Posner4
1 IEAP / CAU Kiel, Extraterrestrische Physik, Kiel, Germany ISNet, Athens, Greece
3 National Observatory of Athens, IAASARS, Athens, Greece NASA Headquarters, Heliophysics, Washington DC, U.S.A.
REleASE proton intensity forecast based on ACE/EPAM electron data
Abstract
A major hazard on human and robotic space exploration activities is the sudden and prompt occurrence of solar energetic ion events. In order to provide up to an hour warning time before these particles arrive at Earth, relativistic electron and below 50 MeV proton data from the Electron Proton Helium Instrument (EPHIN) on SOHO were used to implement the 'Relativistic Electron Alert System for Exploration (REleASE)'. It has been demonstrated that the analysis of relativistic electron time profiles provides a low miss and false alarm rate. High Energy Solar Particle Events foRecastIng and Analysis (HESPERIA) is a project funded within the European Union's Horizon 2020 research and innovation program (PROTEC Call: Space Weather). Within this project the REleASE forecasting scheme was rewritten in the open access programming language PYTHON and will be made public. As a next step, we have analyzed the possibility to also use, along with relativistic electrons (v > 0.9 c) provided by SOHO, near-relativistic (v <0.8 c) electron measurements from other instruments like the Electron Proton Alpha Monitor (EPAM) aboard the Advanced Composition Explorer (ACE). This would prove to be particularly useful during periods that SOHO does not provide continuous near real-time data. We show that the ACE/EPAM observations can be adapted to the REleASE forecasting scheme to provide reliable SEP forecasts. A comparison of measured and forecast proton intensities by SOHO/EPHIN and ACE/EPAM will be presented. In future we will quantify the false alarm rate and detection probability of solar ion events.
Electron intesities
SOHO/EPHIN vs. ACE/EPAM
Figure 6
The left panel shows the same plot as figure 5 but with corrected EPAM data. The EPAM electron intensity was background subtracted, raised to the power of 1.02 to correct for different correlation at higher intensities and divided by ten. This mapped EPAM data can be used as input for REleASE. The right panel shows the comparison of the electron rise parameter. This parameter is the linear slope of the log of the electron intensity. A correlation between of the rise parameter between EPHIN and EPAM can not be seen. REleASE is based on forecast matrices which correlate the electron intensity and the rise parameter with future proton intensities (see figure 7).
Because of the much stronger dependence of the forecast on the electron intensity we decided to use the shown EPAM rise parameter and the electron intensity as input for REleASE. +
Introduction
Figure 4
The main goal REleASE in the framework of the larger HESPERIA project is to analyze the possibility of using REleASE-style forecasting that so far is based on relativistic electron data (v > 0.9 c) provided by SOHO/EPHIN to now work near relativistic electron data provided by ACE/EPAM (v < 0.8 c). EPAM data has a lower time resolution over 5 minutes, while EPHIN's time resolution is one minute.
The above figure shows the time profile for year 2014 of electrons measured by EPHIN in black and EPAM in red. The EPAM electron intensity is shifted down by a factor of 100 for reasons of comparison (red on top). One can see that both time profiles show similar behavior. Any increase in EPHIN data shows an increase in EAPM as well.
The figure also shows that there is a higher background in EPAM data (10^-1) with respect to the EPHIN data (below 10^-2). Note that the EPAM data is already shifted down by a factor of 100.
~ min.
Figure 1
Sketches of a Solar Energetic Particle (SEP) event. While traveling along the interplanetary magnetic field lines relativistic and near relativistic electrons arrive at Earth ~30 minutes earlier than than ions below 50 MeV/n. This effect is used by REleASE to forecast proton intensities with near-realtime measurements of relativistic electrons. In reality SEP's may have a longer path from Sun to Earth due to magnetic disturbances and scattering. Posner 2007 found:
1. Relativistic electrons always arrive at 1 AU ahead of non-relativistic SPE ions.
2. Coming from one source with “identical” propagation conditions, significant correlations between electron and proton time-profiles exist.
3. Therefore, a matrix to forecast proton intensities was developed.
Posner, A., Up to 1-hour forecasting of radiation hazards from solar energetic ion events with relativistic electrons, Space Weather, Vol. 5, S05001, doi: /2006SW000268, 2007.
Figure 7
REleASE forecast matrix for one proton channel intensity in 60 minutes. The REleASE input (electron intensity y-axis and rise parameter x-axis) are converted to a future proton intensity (output) which is shown color coded. The matrix is based on EPHIN data from year 1998 – 2002 (learning phase).
Figure 8
Comparison of forecast proton intensities based on EPHIN (red) and EPAM (green) data with measured proton intensities (black). For the May 2012 SEP event both forecast are in good agreement with the measured proton intensity.
Conclusions / future work
– The original REleASE software ( was rewritten in the open access programming language python.
– Near realtime electron data from ACE/EPAM were mapped to SOHO/EPHIN electron data to use them as direct input to the REleASE forecast scheme.
– The two new REleASE versions are running on the HESPERIA web server. The forecasts are displayed on the HESPERIA project web page:
– The forecasts produced by the new REleASE versions are displayed in one graphic (as seen on the right side) which is refreshed every 5 minutes.
– Future plans are to integrate an alert system, make the data public for download and to deliver a web based plotting tool to display the data for customized time periods.
– There is still work to do before the above tasks can be accomplished. False Alarm Rates and the Probability of Detection for SEP events will be updated by using EPHIN and EPAM data from 2008 to 2015.
Figure 5
This figure shows a quantitative comparison of the EPAM and EPHIN electron intensity of year The x-axis shows the EPAM electron intensity and the y-axis the corresponding electron intensity measured by EPHIN. For this comparison the mean EPHIN electron intensity of the 5 minute EPAM measurement interval was taken. The black line represents a ratio of 10 between EPAM and EPHIN data (EPAM 10 times higher).
One can nicely see the higher EPAM background, a good correlation for medium intensities and a not so good correlation for higher electron intensities.
The conclusion of this figure is that there is a correlation between EPAM and EPHIN data but the EPAM data has to be mapped to the EPHIN data before they can be used as input for the REleASE scheme.
Figure 2
One goal of the HESPERIA project is to create a copy of the existing REleASE software in the open access programming language PYTHON and make the new code available to the public. Above one can see the flow chart of the new REleASE forecast scheme as implemented on the HESPERIA web server. The software searches for new near-realtime electron data every minute (step 1). If new data are found, the software downloads and processes the data (step 2 and 3) to provide forecasts of the expected proton intensities (step 4). The forecast results are then displayed on the HESPERIA web page in step 5 (
Figure 3
This figure shows the REleASE proton forecast made by the original software on the x-axis and the rewritten PHYTHON version on the y-axis for a solar particle event in May This functional test demonstrates as an example that both software codes provide identical forecasts.
Acknowledgements
This work was done in the frame of the HESPERIA project. This project has received funding from the European Union's Horizon 2020 research and innovation program under grant agreement No
[Image Ref.: nasa.gov]