Deliverable report on WP5-5.1 NKUA-IZMIRAN

Transcription

1 Deliverable report on WP5-5.1 NKUA-IZMIRAN Generation of ALERT signal for proton and solar neutron ground level enhancements using NM data G. Souvatzoglou, E. Mavromichalaki, E. Eroshenko, A. Belov, V. Yanke, O. Kryakunova NKUA-IZMIRAN, October, 09

2 Document information Project Project acronym: NMDB Project full title: Real-time database for high resolution Neutron Monitor measurements Grant agreement no: Funding scheme: Combination of Collaborative Projects & Coordination and Support Actions Project start date: Project duration: 24 months Call topic: INFRA Scientific Digital Repositories Project web-site: Deliverable Report: WP5.1 NKUA-IZMIRAN Period Covered: Actual Submission Date: Editors: E. Eroshenko, E. Mavromichalaki Authors: G. Souvatzoglou, E. Eroshenko, A. Belov, L. Dorman, V. Yanke, O.Kryakunova Draft/Final : Final No of pages (including cover) 15 Keywords: GLE, GLE Alert, solar energetic particles, Real time NM data, solar neutron enhancement,

3 Contents 1. Introduction 3 2. Criteria of the GLE ALERT signal at each station (prealert) and creation of a common signal for proton events Alert system elaborated by NKUA Alert system elaborated by IZMIRAN 7 3. Auto testing of the ALERT system 9 4. Description of IZMIRAN web page for GLE ALERT system Explanation of the Internet Alert project for proton events Proposal of TAU Team Solar neutron GLE Alert system Illustration of the real signal generation and auto testing of a system Description of the site of internet project on solar neutron Alert Summary. 14 GLE Alert for proton and solar neutron ground level enhancements using NM data 1. Introduction. GLEs are defined as transient enhancements of the solar cosmic ray intensity observable at the Earth which are able to influence the Earth s environment and human life. One of the most important goals of the NMDB project is the creation of a system for high-resolution registration and evaluation of this type of events in real time. Several groups (NKUA, IZMIRAN, TAU, ALMATY, ARAGATS) participating in the NMDB project run various GLE Alert functions some of which are of use for real-time applications [1-8].. Within the cooperation of NMDB, these groups work together to provide the best of possible Alert system. The main contribution in the realisation of Alert system in real time mode was made by NKUA and IZMIRAN groups which started and continued this work in one direction. Almaty Team contributed a lot in the creation of solar neutron Alert as having large experience in the study of solar neutron enhancements. Yerevan (Aragats) has worked on the preparing of different scenarios of warnings and alerts based on the measurements of Aragats complex (two levels of NM, muon telescope, solar neutron monitor, and relevant observations onboard of satellites). They started testing of various methods, and did not get certain result and reliable Alert system so far, it may be obtained only after the real extreme events occur on the Sun. They also worked on developing a methodology for classifying different solar modulation events, including GLEs initiated by solar protons, or neutrons. But creation of the main Alert system was initiated and turned out to be possible only due to theoretical conclusions and calculations by Dorman [1, 2, 3], so, the contribution TAU is difficult to be overestimated. TAU very actively participated in the discussion of all steps on the Alert system elaboration. Besides, TAU developed its own ALERT system based on the data of a single station, which we shall mention below. The Alert software is based on the idea that the early detection of an Earth-directed solar cosmic ray event by NMs gives a good chance of preventive monitoring SEP-flux rise. The cosmic ray-flux in the energy range above 500 MeV/nucleon cannot be recorded by satellites with enough accuracy because of their small detecting area. However, it can be measured by ground-based NMs with high statistical accuracy. The principle algorithm for generation of Alert signal was described in many articles by Dorman and co-authors [1, 2, 3]. GLE is more often purely proton event, but can be preceded by an increase of intensity of solar neutrons, as, for instance, in the event on May 24,1990 (GLE-048) and October 28, 03 (GLE067) or in general without observable proton increase, for example, on August 25, 01. As principles of discrimination of proton and neutron increases are absolutely various, we

4 created two independent Internet projects for detection of such events and formation alert signal which are named as Alert of Solar protons and Alert of Solar neutrons. 2. Criteria of the GLE ALERT signal at each station and creation a common signal. The approach to solving this problem is common for IZMIRAN and NKUA groups, and their systems are different only in some details that will be shown below. It is worth notice that NKUA made a giant work when processed all of short resolution (5- and 1 minute) data over the 11 events of the last solar cycle (from 00 to 07) implementing their model to these data. It allowed us 1) to be convinced in the reliable operating of ALERT program with the retrospective data; 2) to analyze a large statistical material and choose the most optimal parameters (base period, threshold level, time resolution and so on) for the ALERT signal formation [8]. Results of these runs are given in the Table 1. Table 1 GLE Events Ru n Time wind ow (min) Pre- Alert point s Num ber of stati ons Thre shol d 15 /4/ /4/ 01 4/ 11 / T T T F T T T T F T T T T T F T T T T F T T T T T F T T T T F T T T T T F T T T T F T T T T T F T T T T T T T T T T F T T T T F T T T T T F T T T T F T T T T T T T T T T F T T T T T T T T T T F T T T T F T T T T T F T T ,5 T F F T F T T T F T T ,5-2 T T T F T T T T F T T ,5-2 T T F F F T T T F T T ,5 T T F F T T T T F T T ,5 T T T F T T T T F T T ,5 T T F F T T T T F T T ,5 T T T T T T T T F T T ,5 T T F T T T T T F T T ,5 T F T F T T T T F T T T T T F T T T T F T T T T F F T T T T F T T T T F F T T T T F T T T T F F T T T T F T T T T T F T T T T F T T ,5 T T T F T T T T F T T T T T F T T T T F T T ,5 T T T T T T T T F T T 7 The best parameters for the NKUA Alert system with no false alarms are obtained in the run 71 and are the following: a) 3 pre alert points b) 3 stations in alert mode for general alert c) 15 min time window 26 /1 2/ /8/ /1 0/ /1 0/ 03 2/ 11 / /1/ 05 /1/ /1 2/ 06 Error Alert s

5 d) Multiplier Ν=2 The best parameters for more sensitive system (run 140) with 7 false alarms are a) 4 pre alert points b) 2 stations in alert mode for general alert c) 15 min time window d) Multiplier Ν=1.5 Comparing the Alert times given by GOES satellites with those ones given by the NKUA GLE alert system it is resulted that the Alert times by the NMs are always several minutes earlier. It is presented in Table 2 obtained from offline analysis of all the GLE events from 01 till today. Table 2 GLE Flare Onset, given by GOES 100MeV Integral Flux exceeded 1pfu GOES (1 st alert) ATHENS GLE ALERT RUN /4/01 13:59 13:19 14:21 13:59 13:59 13:59 13:59 13:59 14:04 14:04 14:04 13: /4/01 2:43 2:11 3:11 2:43 2:43 2:44 2:43 2:43 2:48 2:48 2:48 2: /11/01 16:58 16:03 17:07 16:58 16:58 no 16:58 16:45 no no 17:10 16: /12/01 6:07 4:32 6:14 no no no no no no no no 6: /8/02 1:38 0:49 1:48 1:38 1:38 1:46 1:34 1:34 1:35 1:37 1:35 1: /10/03 11:23 9:51 11:51 11:23 11:23 11:18 11:23 11:23 11:31 11:39 11:31 11: /10/03 21:17 :37 no 21:17 21:17 22:11 21:17 18:06 21:35 21:37 21:35 21: /11/03 17:41 17:03 17:56 17:41 17:41 17:42 17:41 17:39 17:41 17:41 17:41 17: /1/05 no no no no no no no no no no 69 /1/05 6:50 6:36 7:04 6:50 6:50 6:51 6:50 6:50 6:53 6:53 6:53 6: /12/06 2:53 2:48 3:12 2:53 2:52 2:54 2:53 2:52 2:54 2:54 2:52 2: Alert system elaborated by NKUA. One minute Data from NM stations on Earth are processed in order to search for the start of the GLE. The initiation of a GLE is identified as the simultaneous detection of the enhancement in at least three NM stations. The Block-scheme of the ALERT producing with implementation of NKUA algorithm can be seen in Figure 1. Every one minute and for every station the program gets as an input one new count. According to the algorithm this value is compared with the threshold and the file level_file.txt is updated according to the result of the comparison. Also the variable J is increased by one each time a pre-alert point is found or else is returned to zero. If J is equal to three then we define a local station alert. When one station reaches the local station alert state the program stays at this condition for 15 minutes. This time window is created with the use of the variable countdown and gives to our system enough time to find if there are also some other stations at the same condition in order to establish a GLE alert if their J number is greater than three. The entire algorithm is executed every one minute and some of the above results are saved as.txt files for further calculation. A Supervision program checks every minute the status of every station. If this program detects at least 3 stations in station alert mode in a time window 15 then produces a General GLE Alert Signal

6 Nowcount=New data value Calculate new threshold NO Nowcount >= Threshold? YES J=0 J=J+1 Make level file J Make level file J NO J >= 3 YES Countdown=15 NO Countdown >1? YES Create \StationGLEresult file Print to the screen still searching Append alert1\stationgleresult file Print to the screen GLE Base station alert Wait 1min Figure 1. Block scheme of the GLE Alert producing by the NKUA algorithm At every minute a new web page based on the results of the NKUA algorithm is drawing automatically that searches for GLE alert in every station of the NMDB network and on algorithm that searches for the General GLE alert. In this Web Page every pre alert point of a station is represented with a coloured bar. The system works with moving threshold M+2σ If 3 pre alert points are located in succession a Local Station alert is defined. If 3 at least stations are located in alert mode in a time window of 15 minutes, a general alert message is posted. The page is located in the following URL A Typical representation of the page in alert mode is given in the following Figure 2

7 Figure 2. Web page of the results of the NKUA real time GLE Alert system. Stations Lmks, MCRL, Oulu and Rome showed an increase above the threshold during 5 0ne-minute intervals. In result, the General Alarm Signal was generated. The system is running in real time based on NMDB stations updated every minute. 2.2 Alert system elaborated by IZMIRAN IZMIRAN group made a little different realisation of similar algorithm on the Alert signal producing. Block scheme of the IZMIRAN version of Alert system is present in Fig. 3. In order to establish the Alert system, a two-step procedure is working: searching for Alert for each station and then, generation of General Alert. Figure 3. Block-scheme of a system for generation of the GLE ALERT by IZMIRAN system. Firstly for each station at every minute moving BASE value M is determined and then threshold value is defined as M +N * Sigma (1< N <3) by the running mean M.

8 1-minute data at each station is compared with its threshold during the last 12 minutes. This allows the use even the stations which updated once per 5 or 6 or 10 minutes (socalled, delayed stations). When the measurement exceeds this moving threshold more than 2 sigma, the system marks a pre-alert point for this minute. When an increase is observed simultaneously at 3 stations the marker appears in the column Watch. ( When the number of stations with increased values became 4 then the marker appeared in Warning. When the increase is registered at approximately half of operating stations the Alert the marker appears in the column Alert and Alert signal is generated and sent out to users. If this program detects at least K stations in station alert mode за текущие 12 минут then produces a General GLE Alert Signal и рассылка. These operations are illustrated in Figure 4. Figure 4. Illustration of the GLE Alert by the IZMIRAN Alert system. All the results are written in Protocol.txt file where one can see which station at which time uploaded its data, and every minute variation at each station relatively base value. This information is stored during the last three hours. The main important moments in the creation of Alert signal are the following: Choice of the base period. The first full hourly interval preceded GLE is chosen as the base period. This period is moving with the current time. Choice of a threshold level and criteria of an alert signal formation. The choice of a level of selection of events at formation of alert signal is very important and critical. The aspiration to lower selection level (for example, 2.5 σ) creates the problems with false events. The choice of high level of selection (for example, 5 σ) leads to the admission of small GLE. Really, statistical accuracy of the minute data of the neutron monitor18nm64, which are in the majority, is nearby 1 %. We choose level of selection of 3 % (2.5 σ )

9 Fig. 5. The onset of GLE60 at different polar stations; Insertions at a level of 5% shows the onset Choice of the time-resolution of data used. Having developed an alert signal at each station, at a following stage it is necessary to unite this information and to develop the general signal. Can happen that at small and enough anisotropic GLEs, for parts of stations it will not be feasible to get an alert signal. Therefore at development of general ALERT signal it is necessary to use soft enough conditions to consider a possible situation of possible anisotropic GLE. The analysis of retrospective events has shown that at generation of general signal ALERT it is enough to have alert signal on 60 % considered stations. It has proved to be true on 12 events investigated by us without formation of a false signal. As it clear from Fig.5, for formation an alert signal it is enough to use the data of several (4-6) high-latitude stations in regular intervals located by a longitude. For reliable definition of spectrum GLE it is necessary to include in addition middle-latitude and even equatorial stations. Depending on used model it can be from 10 to all possible number of stations, publishing data in a real time mode. Despite these two systems are very similar in general, they have some small distinguishes. For example, Athens system performs three repeating procedures to define enhancement at one station and uses >= 3 stations with enhancement >2 sigma for issue General Alert signal whereas IZMIRAN version applies two repeating and uses >N/2 stations with enhancement >2sigma. These two versions have different design and are written in different languages: NKUA version in Basic, IZMIRAN- in Perl, with a chance to transfer it to Linux. IZMIRAN version also uses special Test program for checking the normal work of the Alert system. It is more adjusted to the real stage of database since considers not only current minute but 12 preceded minutes. 3. Auto testing of the ALERT system The GLE events are very rare therefore, it is necessary to provide continuous testing of software and hardware. With this aim two copies of the program have to start. The first one analyzes the real current data, and the second is used for system testing. In current date a year is replaced by the year in which the real GLE was observed in the same month. As a result, within a year the second program will monthly generate test alert signal as shown in table1, where the number of GLE in each month is taken from the former years. Table / 07/14 12/26 4/18 5/06 7/14 8/24 9/29 0/28 1/ /11; /13

10 06/15; /25 In Table3 the first line shows the number of months in the year. Second line indicates the number of GLE (by the International Catalogue by Shea) in each month. Third line gives the dates of those GLEs occurring. 4. Description of the IZMIRAN web page for GLE ALERT SYSTEM. The references on the Internet projects are placed by the address: then: NMDB Online Access Tools, GLE ALERT SYSTEM IZMIRAN ( AlertAndProfilesPrognosing/index.htm). In Fig. 6 the image of the web page of IZMIRAN GLE Alert system for proton events is presented Figure 6. Web page of the Internet project on the proton GLE Alert (IZMIRAN version) 4.1 Explanation of the GLE Alert Internet project for proton events. 1. Subscribing on automatic ALERT mail messages 2. Viewing the RESULT of current ALERT analysis for the last 12 minutes (as in Fig. 4. If the mark appears in Watch and Warning columns we may expect a total ALERT. In the first column there is the current date, in the second one- number of stations submitted data to nmdb, third column indicates the number of used stations on the corresponding date (we see some delay in data updating), the last column shows number of stations where CR variations exceeded 2 sigma. 3. Solar CR spectrum and Description. Results obtained for GLE by retrospective data on the basis of cut model for GLE parameters definition. 4. Protocol of working program for real time data. There are the data from used stations for the last several days where you can see the real state of the station at each moment.

11 5. Protocol of working program for retrospective data. There are the data from used stations for several days where you can see the real state of the station at each moment. 6. Other Version of ALERT system established at Athens University 7. Last Xray+GLE+Protons EVENTs And Full List of GLEs. List of GLE, X-ray and Proton events. If you click blue line you get the full picture of event by ground and satellite data. 8. Real Time parameters of Space Weather: solar, solar wind, IMF and geomagnetic activity data which may be useful for the analysis GLE. There are also references on the sources of information. 9, 10. NOAA Space Weather Alert and Scales. 11. Examples of code in Perl for searching for solar protons 4.2 Proposal of TAU Team TAU Team, except of creation of general algorithm, developed and checked in continue mode method of real time alert of the beginning of GLE on the basis of independent one-min data from NM at a single station. They determined probabilities of false alert and probability of missed trigger in dependence of NM accuracy per one minute and amplitude of GLE. These results are valuable for a construction of other ALERT systems. TAU alert system is placed by the address: This method is described in the paper Alert system for NMDB computer worked independently and separately for each station in real time for determining automatically the start of GLE or SNE by L. Dorman and placed on the nmdb site: ( q=node/67, Alert for NMDB stations-tau.pdf). In principle, this Alert is possible also to produce by NMDB server which automatically collected one minute data from each NM of NMDB consortium. It allows also to determine the nature of event (proton GLE or/and SNE). Historical GLEs show very fast increase of amplitude in the start of event. For example, in great GLE of February 23, 1956 amplitudes of increase in the Chicago M were at 3.51 UT - 1%, at 3.52 UT 35%, at 3.53 UT 180%, at 3.54 UT 280 %. In this case, the missed trigger can be only for the first minute at 3.51 UT. Moreover, in this very big event for determining of the event start will be enough only the first two minutes. The method can be used in many Cosmic Ray Observatories where one-minute data are detected. Since the frequency of ground SEP events increases with decreasing cutoff rigidity, it will be important to introduce this method in high latitude Observatories. For low latitude Cosmic Ray Observatories the GLE increase starts earlier and the increase is much faster; that is important for earlier forecasting of dangerous situation caused by great SEP events. Of course, at these stations with high rigidity the GLE may be observed very rare, only during very extreme event on the Sun. But these mountain stations (Lomnitsky Stit, Jungfraujoch, Almaty, Aragats, Mt. Hermon) are fitted to monitoring of the Solar Neutron Enhancements. Thus, the software developed and applied to these groups (mountain, low latitude stations) is very useful for solar neutron monitoring. 5. Solar neutron GLE Alert system. Monitoring Solar Neutron events in real time using Neutron Monitor data (IZMIRAN, ALMATY) The monitoring of high resolution NM data is carried out with the aim of selection solar proton and neutron ground level enhancements. Selection of neutron enhancement is difficult because of: 1) These enhancements are very rare and very short (one- several minutes); 2) they should be selected with very low threshold (4σ); 3) they may be observed practically at one-two of several low latitude mountain stations. It is impossible to pick up such events automatically with certain assurance. Thus, the system creates a list of stations pretending on the SN registration at every moment. The system calculates an efficiency of each station in most favorable moment (close to local noon, accounting inclination of the Earth axis to the equator, altitude ) for SN

12 registration. Besides, only the enhancements followed by X-ray flares of >X3 class are accounted ( The Table is formed for each station at every moment and written to Protocol, where A,%, sigma (estimated in % and sigma) is the CR variation relatively base level at tested station, Apole,%, sigma (in percentages and sigma) is the CR variation relatively base level at sub polar station which is used for comparison and indicating of a proton enhancement. Xray, MkW/cm2 powerful of the X-Ray flux, Index - is some kind of indicator: Index = 10 increase in the favorable geometric cone, Index =-10 increase out of favorable cone, Index = 01 Index of control, when an enhancement is observed at the polar station but not observed at tested station. Table 4. An example of typical Protocol for each station created. Date hrs:min:s A,% A,sigm Apole,% Apol,sigm Index Xray,MkW/cm 2 ALERT nsigma=4 <m>= :59: TEST :23: N :26: N :53: N :02: POLE :31: N :37: N :59: TEST :19: N :35: N :15: N :51: N :59: TEST :23: N :36: N :57: N When you enter Example of code you will get the following list: :49 aatb.01v.txt CR variations for aatb station for 3 hours :49 apty.01v.txt CR variations for apty station for 3 hours :49 LastData.01c.txt counting rates for the last retrieving data :49 LastData.01v.txt CR variations for the last retrieving data :39 main.pl! working program :52 name.txt List of nmdb stations with markers for used ones :22 Protokol.txt comments on program working :49 Stop.txt information for the last moment There is an example of the working program (main.pl!) and some auxiliary files for the date shown on the left side of list. Figure 7. Block-scheme of the elaboration of the solar neutron enhancement signal

13 6. Illustration of the real signal generation and auto testing of a system Block-scheme of a system for selection of applicants (or, pretenders) to neutron GLE is present in Fig 7. Search for effect of solar neutron is carried independently by each station on the base of one-minute NM data with incorporating of X-ray channel data. Event is enlisted in applicants for solar neutron increase if following conditions are simultaneously satisfied: a) In the absence of increase at basic polar station at tested station the increase > 4σ is observed; b) The station is in a zone of direct visibility on the Sun within some angular cone, near noon; c) The flux of Xray exceeds the threshold (>100 mkw/m2). This case is presented by line 1 in Fig.7. As in the case of GLE Alert for proton enhancement for the base period the full preceding hour is accepted. A threshold level was chosen 4σ both for referenced polar and tested stations. If thus the stream of X-ray radiation does not surpass threshold value such increase does not join in number of applicants, and is entered only in the minutes. In fig. 7 it is presented by a line 2. It is obvious that the report will contain basically such events. If increases at polar station exceed threshold, in not dependences on variations at equatorial station such event is also allocated and can be used at the analysis of quality of NM data or in general can concern proton GLE. In fig. 7 it is presented by a line 3. And, at last, if variations at basic and tested stations have not reached threshold values such events are not considered at all. When the program find the increase really identified with the CR enhancement it should send out warning signal to users. Auto-testing of a system Solar Neutron Alert. Not to break process of selection of solar neutrons, auto-testing is carried near to an exit of station from a cone of visibility of a stream of solar neutrons. With that end in view in Ttest=1:59 LT on each station provided that the stream of X-ray radiation less than threshold value, is thrown a false information for check of working capacity of system. This is a 10% increase of the counting rate variation at tested station and the same decrease at polar station. The X-ray flux is made also of 10% higher than threshold value. Test checking is entered in the minutes as TEST and is missed in the further processing of a signal. This case is presented by line 4 in Fig.7. The described technique is realized in the Internet project. The result of the analysis is accessible in a kind ftp Protocol. Subscription possibility (or its cancellations) on post dispatch if the system has produced the applicant for neutron increase is provided. The typical Protocol which is formed for each station is presented in Table Description of the site of internet project on solar neutron Alert or, then: NMDB Online Access Tools, and: SOLAR NEUTRON MONITORING IZMIRAN.

14 Figure 8. Web page on the solar neutron monitoring 1. Data from each station really and potentially participating in the SNE monitoring. Click lines on the site there are counting rates and CR variations for each station for every minute. 2. Subscription on the automatic mailing of the event onset. Dialogue window of subscription and management. 3. List of near equatorial mountain neutron monitors. 4. Information about solar neutron telescopes. 5. List of solar neutron telescopes. 6. Solar Angle calculator for Neutron Telescope Network 7. Neutron flight calculator. 8. Real Time Parameters of Space Weather (Relevant data) 9. NOAA Space Weather Alerts 10. NOAA Space Weather Scales 11. Examples of Perl code software for the searching for solar neutron enhancement 12. List of publications on the solar neutrons. In the creation of this site (internet project) large work was performed by IZMIRAN, Almaty and TAU Teams. 8. Summary 1) The algorithm of generation of alert signal of ground level proton increase on the basis of the one minute data from nmdb is developed and realized. Two versions of the Alert system and the Internet projects on the implementation of this system in real time were in use by the end of August 09.The developed Internet projects provide possibility of formation of the electronic

15 warning signal with the GLE start and its automatic dispatch. 1) In project development it is planned to add system with the module for an estimation of GLE spectrum and the forecast on its basis of the lower energy proton fluxes from solar flares, in particular, protons with energy >100 MeV which are most dangerous for technical and biological influence. 2) The elaborated system of selection of applicants for solar neutron increase allows us to form the list of possible increases in real time and to carry out the internal control of system. The developed Internet project provides possibility of formation of the electronic warning message and its automatic dispatch. At the given stage the main difficult for the effective operating of created system is connected with irregular updating of the nmdb: not all stations yet are able to retrieve their data every minute, a delay in updating may reach from 5 minutes up to 24 hours. But this is technique problem which may be solved during the time. Besides, some software improving may help to avoid a part of this problem, especially with the stations delayed data on minute intervals. Large contribution in Deliverable WP5.5.1 was made by NKUA, IZMIRAN, TAU and Almaty Teams. Aragats Team has tried to elaborate tis own Alert system based on the data from Aragats complex of detectors, but this work is not finished yet. At present two ALERT systems are functioning in real time with nmdb data: at NKUA and IZMIRAN. Corresponding links between these servers and nmdb are provided. These systems should work in parallel and be ready to pick up the events in the new solar cycle. Only after real solar events the conclusion may be done which system is more preferable. References 1 Dorman, L., Zukerman, I. Initial Concept for Forecasting the Flux and Energy Spectrum of Energetic Particles Using Ground-Level Cosmic Ray Observations. Adv. Space Res., 31, , Dorman L., L. Pustil nik, A. Sternlieb, and I. Zukerman, Using ground-level cosmic ray observations for automatically generating predictions of hazardous energetic particle levels, Adv. Space Res., 31, , Dorman L.I., 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 Transactions on Plasma Science, 32, No 4, , Souvatzoglou, G., Mavromichalaki, H., Sarlanis, C., Mariatos, G., Belov, A., Eroshenko, E., Yanke, V. Real-time Alert in the ANMODAP Center for December 13, 06. Adv. Space Res., 43, , Mavromichalaki H., Souvatzoglou C., Sarlanis C., Mariatos G., Papaioannou, A., Belov Α., Eroshenko E., Yanke V., Using the real-time Neutron Monitor Database to establish an Alert signal, Proc. 31 th ICRC, Poland, ID 1104, Anashin V., Belov A., Eroshenko E., Krjakunova O., Mavromichalaki H., Ishutin I., Sarlanis C., Souvatsoglou G., Vashenyuk E. and Yanke V., The ALERT signal of ground level enhancements of solar cosmic rays: physics basis, ways of realization and development. Proc. 31th ICRC, Lodz, ID 1104, H. Mavromichalaki, G. Souvatzoglou, C Sarlanis, G. Mariatos, A. Belov, E. Eroshenko, V. Yanke, R. Pyle, Statistical analysis of the real -time GLE Alert system at the ANMODAP center, Proc. FORGES Belov A., A. Asipenka, L. Dorman, E. Eroshenko, O. Kryakunova, N. Nikolayevsky, A. Shepetov, V. Yanke and Zhang JiLong, A real-time search for solar neutron events in the data of high-altitude neutron monitors, Proc. 31 th ICRC, Poland, ID 1107, 09.