19th ECRS 2004 (Florence, 31 Aug-3Sept 2004)

1. 19th ECRS 2004 (Florence, 31 Aug-3Sept 2004) NATIONAL AND KAPODISTRIAN UNIVERSITY OF ATHENS PHYSICS DEPARTMENT NUCLEAR AND PARTICLE PHYSICS SECTION COSMIC RAY GROUP Alert system of ground level cosmic-ray enhancements operated at the Athens Neutron Monitor Network in real-time H. Mavromichalaki (1), G. Souvatzoglou (1), C Sarlanis (1), G. Mariatos (1),A. Belov (2), E. Eroshenko (2), V. Yanke (2) (1) Nuclear and Particle Physics Section, Physics Department, Athens University, 15771 Athens Greece emavromi@cc.uoa.gr (2) Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation, Russian Academy of Science, 42092 Moscow Russia Abstract The Athens Neutron Monitor Network in real time initiated in December 2003, provides data from twelve real-time stations, useful for real-time monitoring of cosmic particle fluxes. We have recently started a more ambitious program, the Alert program for the forecast of the arrival of dangerous middle energy particles on the Earth’s surface. The program processes these data taken from this Neutron Monitor Network and informs us about the onset of ground level enhancements. In this way there is enough time to protect technological systems. This would save money, data and expensive equipment on Earth and/or in Earth’s orbit. The continuous growth of the electronic industry has offered us many possibilities for electronic appliances which have invaded in every domain of our life. Because of their nature they are sensitive generally to electromagnetic and particle radiation. This is why now more than ever it is necessary to have an accurate and reliable forewarning about the arrival or these dangerous particles. Predictions of solar activity are important for various technologies, including operation of low-Earth orbiting satellites, electric power transmission grid, high-frequency radio-communications etc. Real Time Neutron Monitor Stations Participating in this Project Principles of SEP Radiation Hazard Forecasting • Time-profiles of solar CR increases are very different for different great SEP events. The real-time research is described as following: • Determination of energy spectrum above atmosphere from the start of SEP event • Determination of anisotropy and its energy dependence • Determination of propagation parameters, time of SEP injection, total flux of SEP as a function of energy • Forecast of expected fluxes and spectrum in space, magnetosphere and space • If the flux is in dangerous levels, the programs run for forecasting Point of View Lat -50°, Long 30° Point of View Lat 60°, Long 30° Athens Neutron Monitor Network Plots “Scheduler” program Athens Neutron Monitors Stations Database Program FORECASTING OF CR INCREASES The next steps of the used feasible and statistically proven method for forecasting are followed: ALERT Program Schematic presentation of the alert system 1.Search for a significant increase in the total counts of the 1, 2, or 5- minute data from several stations. If it is found, go to a state known as “alert-1” 2.i) Estimate the rigidity spectrum of the SEP event ii) Calculate spectra parameters best fitted to the data from at least 3 different stations (Dorman et al., 2003) 3.Evaluate the energy-dependent diffusionconstant for energetic particle propagation in interplanetary space using the rigidity spectra calculated from the three preceding one-minute data. 4.Predict the near Earth spectrum for a time window of ~ 1 hour. Compare on-line GOES measurements for the last several minutes (if available) with previous predictions. 5.If the predicted flux at 100 MeV exceeds the determined thresholdissue an“Alert-2”. Conclusions Recently, an improved method of monitoring the alert situation of the great solar proton events on the basis of on-line data from the Athens neutron monitor network is applied. The developed conception and the described method derive on line the SEP spectrum out of the magnetosphere on the basis of continue registration of cosmic ray intensity by the ground level neutron monitors. It is shown that the use of online data from ground level NMs together with satellite measurements allows the prediction of the SEP integral fluxes for different energies during the first 30-40 minutes of the event and the calculations of the fluency on the long duration events (up to few days). These results lead to the estimation of the expected radiation hazard very useful for the Space Weather studies. Dst Index Acknowledgements: Thanks are due to all colleagues of the Real-time Neutron Monitor stations provided kindly the CR data References H. Mavromichalaki , V. Yanke , L. Dorman , N. Iucci , A. Chilingaryan , O. Kryakunova Neutron Monitor Network in Real Time and Space Weather. Monograph NATO series for space weather infrastructure technology, (in press) 2004 Mavromichalaki, H., C. Sarlanis, G. Souvatzoglou, S. Tatsis, A. Belov, E. Eroshenko, V. Yanke and A. Pchelkin. Athens Neutron Monitor and its aspects in the cosmic-ray variations studies. Proc. 27th ICRC 2001, 4099 L.I. Dorman, L.A.Pustil’nik, A. Sternlieb, I.G. Zukerman, A.V. Belov, E.A. Eroshenko, V.G. Yanke, H. Mavromichalaki, C. Sarlanis, G. Souvatzoglou, S. Tatsis, N. Iucci, G. Villoresi, Yu. Fedorov, B. A. Shakhov, M. Murat, Monitoring and Forecasting of Great Solar Proton Events Using the Neutron Monitor Network in Real Time. IEEE for Plasma science, (in press) 2004 http://cosray.phys.uoa.gr/ ftp://cr0.izmiran.rssi.ru/