Neutron monitors are ground-based instruments that record the byproducts of collisions between cosmic rays and molecules in Earth's atmosphere. When linked together in real-time coordinated arrays, these instruments can make valuable contributions to the forecasting and specification of major space weather events. Neutron monitors can provide the earliest alert of elevated radiation levels in Earth's atmosphere caused by the arrival of relativistic solar particles (Ground Level Enhancement). Early detection of such radiation events is of interest to the aviation industry because of the associated radiation hazard for pilots and air crews, especially for those flying polar routes. A pair of detectors at the South Pole has the capability of making an early determination of the energy spectrum at relativistic energies, which in turn can provide useful forecasts of the intensity of the later-arriving lower-energy particles. Neutron monitors can also act as remote sensors of large-scale interplanetary magnetic disturbances such as interplanetary coronal mass ejections (ICME). A "loss cone" anisotropy (or Forbush predecrease) typically exists some distance upstream of an approaching ICME, and can provide an alert of impending geomagnetic disturbance in major events.

Because of the large detector volume that can be deployed, ground-based detectors remain state-of-the-art instrumentation for measuring high-energy galactic cosmic-rays (GCRs). The most recent results obtained from ground-based observations are introduced to demonstrate how useful informations can be derived from observations of the directional anisotropy of the high-energy GCR intensity. The anisotropy observed with the global muon detector network (GMDN) provides us with a unique information of the spatial gradient of the GCR density which reflects the large-scale magnetic structure in the heliosphere. The solar cycle variation of the gradient gives an important information on the GCR transport in the heliosphere, while the short-term variation of the gradient enables us to deduce the large-scale geometry of the magnetic flux rope and the interplanetary coronal mass ejection (ICME). Real-time monitoring of the precursory anisotropy which has often been observed at the Earth preceding the arrival of the ICME accompanied by a strong shock may provide us with useful tools for forecasting the space weather with a long lead time.

The worldwide network of neutron monitors (NMs) is in operation since the fifties of the last century. Together with the geomagnetic field, it acts as a giant magnetic spectrometer in the energy range from ~500 MeV to ~15 GeV. NM data therefore reflect the spectral variations of galactic cosmic ray particles and the occasional impact of relativistic particles from the Sun. This makes the NM network one of the best suited instruments to describe the Earth's cosmic ray environment in space weather applications.

The Neutron Monitor Database (NMDB) project was funded in 2008/2009 by the European Commission's 7th framework program (FP7). The aim of NMDB is to provide the data of the worldwide network of NM stations in a common format with a high time resolution and in real-time in a single database. Today, NMDB includes the data of ~40 stations, with about 25 stations in real-time. The goal of NMDB is to make the data from all NM stations of the worldwide network available in real-time. The NM count rates are stored as one minute and hourly values in NMDB together with further station information. Although there are already some space weather applications implemented in www.nmdb.eu, the database offers the possibility to improve the existing tools and to develop new space weather applications that include NM data. The data from NMDB is publicly accessible via an easy to use web interface, but expert users can also directly access the database to build new applications, as e.g. real-time space weather alerts.

The present status of NMDB, examples of selected tools and applications, and the different possibilities of data mining will be presented.

Space Environmental Viewing and Analysis Network (SEVAN), is a worldwide network of identical particle detectors located at middle and low latitudes aimed to improve fundamental research of space weather conditions and to provide short- and long-term forecasts of the dangerous consequences of space storms. SEVAN detected changing fluxes of different species of secondary cosmic rays at different altitudes and latitudes, thus turning particle detector network into a powerful integrated device used to explore solar modulation effects. Till to now the SEVAN modules are installed at Aragats Space Environmental Centre in Armenia (3 units at altitudes 800, 2000 and 3200 m a.s.l.), Bulgaria (Moussala), Croatia and India (New-Delhi Univ.) and now under installation in Slovakia, Lomnicky stit). Recently SEVAN detectors were used for research of new high-energy phenomena originated in terrestrial atmosphere - Thunderstorm Ground Enhancements (TGEs). In the report we present the characteristics of SEVAN modules: detector design and electronics, purity and efficiency to detect neutral and charged cosmic ray fluxes, barometric coefficients, daily variations in different fluxes, as well as first joint measurements of solar modulation effects detected in the beginning of 24-th cycle of solar activity.
SEVAN network provides following advantages upon existing detector networks measuring single species of secondary Cosmic rays:

Ground level enhancements (GLEs) are observed as significant intensity increases at neutron monitor measurements, following by an intense solar flare and/or a very energetic coronal mass ejection. Due to their space weather impact it is crucial to establish a real-time operational system that would be in place to issue reliable and timely GLE Alerts. Such a Neutron Monitor Service that will be made available via the Space Weather Portal operated by the European Space Agency (ESA), under the Space Situational Awareness (SSA) Program, is currently under development. The ESA Neutron Monitor Service will provide two products: a web interface providing data from multiple Neutron Monitor stations as well as an upgraded GLE Alert. Both services are now under testing and validation and will probably enter to an operational phase next year. The core of this Neutron Monitor Service is the GLE Alert software, and therefore, the main goal of this research effort is to upgrade the existing GLE Alert software and to minimize the probability of false alarms. The ESA Neutron Monitor Service is building upon the infrastructure made available with the implementation of the High-Resolution Neutron Monitor Database (NMDB). In this work the structure of the ESA Neutron Monitor Service, the core of the novel GLE Alert Service and its validation results will be presented and further discussed.

High-speed data acquisition system for a neutron monitor (NM) is developed in PGI. At the present moment it is installed at the fourth station - in Barentsburg (Spitzbergen, cutoff rigidity 0 GV), Apatity (0.6 GV), Moscow (2.4 GV) and Baksan (Northern Caucasus, 5.4 GV). The system is turned to study fast and transient phenomena into NM. Multiplicity events of M from M = 5 to M = 100 were studied from the Polar cycle to high mountain middle latitude zone. Using the system it is possible to research hadronic core of extensive air shower and local hadronic shower both. Using special procedure we found different populations of particles in NM. Also multiplicity events were carried out.

Cosmic rays (CR) are an important element of space weather and instrument of space weather forecasting. From this point of view, it is necessary to take into account all factors influencing CR intensity. One of these important factors is the influence of atmospheric electric fields (AEF) during thunderstorms on CR intensity. This is caused by local acceleration (or deceleration, depending on the direction of the AEF and the sign of charged particles) of secondary CR particles (mostly muons and electrons, for CR observations in the low atmosphere or underground). We analysed one minute data on AEF obtained by the ESF-1000 sensor in our observatory on Mt. Hermon, and one minute neutron monitor data corrected on barometric effects and on the effect of snow. While AEF does not influence neutrons, we found significant effects in the observed total neutron intensity and in the intensities of different multiplicities. This is caused mostly by soft negative muons, captured by nuclei of lead (instead of the atom's electrons) with the formation of mesoatoms. While the cross section of muons relative to strong interactions is very small (the same order as for neutrino), because the captured muon moves about inside the nucleus with very high density, the probability of muon interaction with nucleus is higher than the decay of muon. As result of this interaction the total energy of the rest muon about 100 MeV goes to the excitation of lead nuclei, with emanation of a few neutrons which are detected by the neutron monitor. Therefore, a neutron monitor is an ideal detector for separating positive and negative soft muons (without using a big magnetic system). We obtained results for positively and negatively directed AEF and show existing significant AEF influence on CR intensity, biggest for small multiplicities. We give a theoretical explanation of obtained results.

Ground level events (GLEs) are the most energetic solar particle events (SEPs) that are detected not only by space born instrumentation but also by ground-based instruments like e.g. neutron monitors. On May 17 2012 at 01:25 UT a M5.1 X-ray flare from the active region 1476 (N07, W88) was detected. The event was accompanied by a type III radio burst starting at 1.30 UT and a coronal mass ejection heading towards Stereo A. The corresponding shock wave passed STEREO A on May 18 at 12:43 UT but missed the Earth. The event onsets of near relativistic electrons have been detected at 06:05 UT, 03:38 UT, and 01:51 UT aboard STEREO A and B (125-335 keV) and at SOHO (250 -700 keV), respectively. In contrast to observations close to the Earth no strong anisotropies have been observed at both STEREO A and B. The neutron monitor network recorded the first GLE for solar cycle 24. The Electron Proton Helium INstrument on board SOHO measured protons with energies of more than 600 MeV (rigidities of more than 1.2 GV). The interplanetary field direction was such that neutron monitor stations with asymptotic direction in the 1 to 2 GV range over Australia were connected best and recorded the biggest increase of 17\% (Apatity and Oulu) with an onset time of 1:52 UT. Data observed close to and at Earth will be presented and the longitudinal structure of the event in the inner heliosphere will be discussed.

In this report the variation of cosmic rays obtained by the global survey method from the world wide neutron monitor network, were studied for 99 events identified with the magnetic clouds. There was found many examples of cosmic ray density decreases in the magnetic clouds that are consistent with the cylindrical symmetry. However, there are some events in which a maximum of the cosmic ray density in the cloud is observed instead of the minimum. In several cases variations of the cosmic ray density have complicated character, with alternating local minima and maxima, possibly reflecting the toroidal structure of the cloud. One can see that galactic cosmic rays not only react to the magnetic cloud in common, but also can display the internal structure of its magnetic field. In many cases one can identify the boundaries of the magnetic cloud according to the data on density and anisotropy of the cosmic rays.

The cosmic ray ground level enhancement (GLE) on December of 13, 2006 is among the strongest recorded events during the previous solar cycle 23. This event is well studied on the basis of ground based data records from worldwide network of neutron monitors. At present it is known that solar protons of relativistic energies following major solar eruptions cause an excess of ionization in the atmosphere and ionosphere, specifically over the polar cap regions. Here we compute in details the ionization effect in the terrestrial atmosphere and ionosphere for various latitudes during this event. The computation of ion production rates is according previously developed numerical model for cosmic ray induced ionization, based on a full Monte Carlo simulations of atmospheric cascade. We apply direct simulation of atmospheric cascade with the CORSIKA 6.990 code using FLUKA 2011 and QGSJET II hadron generators and realistic winter atmospheric model. The ion rates during the event are computed on 30 min step, which allows good precision. The solar energetic particle spectra are taken from recent reconstructions from ground based measurements with neutron monitors. Hence we compute the time evolution of the ion rate production. The full 24h ionization effect is also determined. The obtained results are discussed and compared with previously obtained data concerning ionization profiles during other major GLEs.

Solar energetic particles (SEP)s are accelerated during eruptive energy releases on the Sun and/or by acceleration processes in the interplanetary space. They impinge on the atmosphere of the Earth sporadically, with a greater probability during periods of high solar activity. In some cases they lead to an increase of the intensities recorded by neutron monitors on the surface of the Earth, known as ground level enhancements (GLE)s. The main instrument used to study such events and to reconstruct of primary SEPs characteristics such as energy spectra and anisotropy is based on ground-based data records from standard neutron monitors i.e. the world network of neutron monitors (NM)s. The reconstructed energy spectra and anisotropy bring crucial information to understand the acceleration mechanisms of (SEP)s and their propagation in the interplanetary medium.

An analysis of GLEs from NM data consists of several consecutive steps: definition of asymptotic viewing cones of the NM stations by computation of particle trajectory in a model magnetosphere; calculation of the NM responses i.e. an initial guess of the inverse problem; application of an optimization procedure (inverse method) for determination of primary solar proton parameters: energy spectrum, anisotropy axis direction, pitch-angle distribution. In our model we assume a modified power law energy spectrum and superposition of various distributions for the pitch angle.

Assymptotic directions are computed using the MAGNETOCOSMICS code and realistic magnetospheric models, namely IGRF as the internal model and Tsyganenko 89 with the corresponding Kp index as the external one. The inverse problem solution is performed using non-linear least squares method, namely Levenberg-Marqurdt.

In the study presented here, we analyse several major GLEs of the solar cycle 23 as well as the first GLE event of the solar cycle 24, namely GLE 71 of May 17 2012. The SEP spectra and pitch angle distributions are obtained at different time moments after the event's onset time. The obtained characteristics are compared with previously reported results. In addition satellite data are used for the analysis of GLE71. The obtained results and their application are discussed.

The Castilla-La Mancha (CaLMa) neutron monitor is continuously operating since 26 October 2011. It is located at Guadalajara (40° 38'N, 3° 9'W) at 708 m above sea level and 55 km away from Madrid. It is covering a gap in the Neutron Monitor Data Base (NMDB), thanks to its geographical location, its height above sea level and its vertical cutoff rigidity (6.95 GV). CaLMa is providing counts of galactic cosmic rays (GCRs) with a temporal resolution of 1 min, being the mean count rate 5 c/s/counter. This high cadence allows the monitoring of solar activity by mean the observed variation in count rate. Both in the sort term and in the long term activity, i.e., flare or coronal mass ejections and solar modulation, can therefore be studied with CaLMa's measurements. During this last year, CaLMa has measured variations in the GCR count rate related to interplanetary coronal mass ejections, fast solar wind streams, shocks and stream interaction regions. In this work we analyze the solar wind condition associated to variations in CaLMa's count rate and we compare them with other neutron monitors.

Recording System for Cosmic Ray Measurements at Lomnicky stit.

New system for recording informations on cosmic ray intensity in multichannel measurements of cosmic rays at Lomnicky stit is described. System allows to register data with 1 second resolution, writing barometric pressure and other parameters important for analysis of cosmic rays and their relations to atmospheric processes. In addition to neutron monitor measurements, the system is used in testing mode also for the SEVAN installation at the site (developed by Yerevan Phys. Inst.) and in modified version can be used for the thermal neutron detection (joint device with FIAN Moscow) as well as for dosimetric measurements. In the presentation we discuss the possibility of use the system for space weather monitoring and possible alerts, as well as for studies of relations between cosmic rays and atmospheric electricity. Current status of experiments on cosmic ray studies at Lomnicky stit and in Kosice and their perspectives are reported.

Presentation is created by the realisation of the project ITMS No. 26220120029, based on the supporting operational Research and development program financed from the European Regional Development Fund.

We study the ground level enhancement event of December 13 2006 ( GLE70) by analyzing and quantifying the ionization effect of the high energy solar protons on the lower ionosphere, as monitored by two different ground-based observational tools. The GLE70, triggered at 0240 UT by the powerful X3.4 class X-ray Solar flare, has been detected by the ground-based network of neutron monitors (data stored by Neutron Monitor Database, NMDB, http://nmdb.eu ), even at midlatitudes, on one hand. Large attenuation of amplitude in coincidence with increase of phase of the Very Low Frequency (VLF< 30 kHz) wave propagating on the night path between the Tx NAA/24.0 kHz (Main, Cuttler) and the Rx at the Belgrade VLF Observatory have been recorded, on the other. Namely, high-energy protons induced severe ionization enhancement of the lower ionosphere, altering the VLF transmission along the Earth-ionosphere waveguide. The event has been recognized by the time correlation between the distinctly enhanced neutron monitor (NM) registration, VLF amplitude decrease/ phase increase, and the satellite measurements of the high energy proton spectra (e.g. GOES, PAMELA).

On the basis of (i) published work on the energy spectra of accelerated protons, and (ii) the stopping power of protons due to ionization, from the PSTAR program (http://physics.nist.gov), we have evaluated the induced ionization rate in the ionospheric D-region (50-90 km in altitude), which is shown to exceed significantly the background ionization rate by galactic cosmic rays (GCR). Ionization effects on VLF wave propagation have been modelled by the traditional Long Wavelength Propagation Capability (LWPC) code, indicating enhancement of electron density profile throughout the D-region by 1 to 3 orders of magnitude, in dependence of height, with respect to regular conditions. The results arrived at are compared and discussed, complementing the two observational methods, to provide an unique and coherent picture of the GLE70.

The author, VZ, acknowledges the Slovak National Scholarship for conducting this research at the Institute of Experimental Physics, SAS in Kosice.

It is obvious now that according to data from the past on big variations of planetary surface temperature on scales of many millions and thousands of years, the Earth's global climate change is determined mostly by space factors, including: the moving of the Solar system around the center of our galaxy, the crossing of galactic arms and molecular dust clouds, nearby supernova and supernova remnants. Another important space factor is the cyclic variations of solar activity and the solar wind (mostly on the scale of hundreds of years and decades). The effects of space factors on the Earth's climate are realized mostly through cosmic rays (CR) and space dust influencing the formation of clouds, thereby controlling the total energy input from the Sun into the Earth's atmosphere. The propagation and modulation of galactic CR (generated mostly during supernova explosions and in supernova remnants in our galaxy) in the heliosphere are determined by their interactions with magnetic fields frozen in the solar wind and in coronal mass ejections (CME), which are accompanied by interplanetary shock waves (producing big magnetic storms during their interactions with the Earth's magnetosphere). The most difficult problem in monitoring and forecasting the modulation of galactic CR in the heliosphere is that the CR intensity in some 4D space-time point is determined not by the level of solar activity at the time of observations and electro-magnetic conditions in this 4D-point, but rather by electromagnetic conditions in the whole heliosphere. These conditions in the whole heliosphere are determined by the development of solar activity over the course of many months before the time-point of observations. This is the main cause of the so-called hysteresis phenomenon in connection with galactic CR solar activity. On the other hand, detailed investigations of this phenomenon give the important possibility to estimate conditions in and the dimension of the heliosphere. To solve the problem described above of CR modulation in the heliosphere, we considered as the first step the behavior of high energy particles (more than several GeV, for which the diffusion time of propagation in the heliosphere is very small in compared to the characteristic time of modulation), on the basis of neutron monitor data in the frame of convection diffusion theory, then taking into account drift effects. For low energy galactic CR detected on satellites and space probes, we also need to take into account the additional time lag caused by diffusion in the heliosphere. We then consider the problem of CR modulation forecasting for several months and years ahead, which gives the possibility to forecast some part of the global climate change caused by CR.

Analysis of the events in cosmic ray intensity caused by high-speed streams from low-latitude coronal holes is presented. The database on Forbush effects created at IZMIRAN, with cosmic ray density and anisotropy calculated by the Global Survey Method (GSM) on the basis of Neutron Monitor network data has been used. From the analysis of the events it was found the dependence of the Forbush effect magnitude on the solar wind characteristics.

On May 17, 2012 the worldwide network of neutron monitors recorded the first ground level enhancement of solar cosmic rays (GLE71) of the current solar cycle.

In this work we present a first attempt to derive the characteristics of this recent proton event, registered also at ground level, by applying an updated version of the NMBANGLE PPOLA model, already used for modeling past GLEs (e.g. GLE70). In general, this model uses as inputs the response of the worldwide neutron monitor network to big proton events and the disturbance level of the geomagnetic field (through the use of kp) in order to retrieve information on: the solar cosmic ray spectrum evolution outside the Earth’s atmosphere; the direction of arrival of the solar cosmic ray flux maximum and the evolution of its spatial distribution; the solar cosmic ray differential and integral fluxes spatial distributions through time. In its current version the model assumes that the primary solar cosmic ray particles during this event are protons. Application of the NMBANGLE PPOLA model to GLE71 shows an initially hard solar cosmic ray spectrum and a flux concentrated mainly above the near-equatorial latitudes moving with time towards southern latitudes; after 02:05 UT the maximum solar cosmic ray flux is always located above the Earth' southern hemisphere. The average differential solar cosmic ray flux of 1GV protons remains at high levels for the whole first 1.5 h of the event ranging between 4d3 particles m-2 s-1 sr-1 GV-1 and 1d5 particles m-2 s-1 sr-1 GV-1.

In this study the initial cosmic ray data required for the model run were obtained from the NMDB (www.nmdb.eu). The derivation of the GLE71 properties through the NMBANGLE PPOLA application is an example of how neutron monitor network data can be efficiently used for space weather modeling and, specifically, for getting information that cannot be directly obtained by space instruments (e.g. the higher energy part of the solar cosmic ray spectrum during the event). The NMBANGLE PPOLA, therefore, inside the context of a neutron monitor network of widely distributed stations, represents a new useful tool for the study of solar physics and space weather providing solar cosmic ray information that is complementary to that obtained by space techniques.

A significant space weather impact (i.e. risks and failures at communication and navigation systems, spacecraft electronics and operations, space power systems, manned space missions, and commercial aircraft operations) is being imposed from Ground Level Enhancements (GLEs) which are defined as significant intensity increases at neutron monitor measurements. A timely and reliable GLE Alert signal requires both the availability of actual-real time data in a continuous data flow scheme. Given the special characteristics of each neutron monitor station (cut-off rigidity, altitude, latitude, longitude), and the underlying common detection design, all NMs can be used as a unified mutli-directional detector. In this work the availability of each NM station with respect to their delivery of real-time data and their continuous data flow into NMDB as well as the characteristics of the NM stations that contributed to the establishment of timely GLE Alerts for the last 13 GLE events will be presented and discussed.

Cosmic ray (CR) Forbush effects and precursors are important for space weather forecasting of phenomena that pose dangers to satellite electronics and other technologies even on the ground. We select Forbush effects observed on Mt Hermon. Then, using data from other stations, we construct for each event diagrams that show precursor effects using the method of ring stations. These precursor effects can be used for forecasting big magnetic storms. We also performed some statistical analysis of the obtained ring station diagrams and discuss the possibility of using the described method in a real time scale.

All CR stations on mountains and at about sea level at middle and high latitudes in winter periods are covered by snow with the depth (in g/cm2) varied in time. To use this data for space weather forecasting, it is necessary to determine the snow effect for each moment in time and correct observation data not only from barometric and temperature effects (as usual), but also from the snow effect. According to observations on Mt. Hermon, the snow effect in the NM total intensity and different multiplicities is comparable with 11-year variation. The other problem is, that with increasing of snow depth, the sensitivity of the CR detector changed - it moved to higher energies. To determine the snow effect in NM on Mt. Hermon, we made the following investigations step by step: 1) we determined the connection of CR intensity observed on Mt. Hermon during periods without snow with CR intensity on stations which are never covered by snow; 2) by finding the regression coefficients we determine the expected CR variations on Mt. Hermon in winter time on the basis of data of stations which in winter time are not covered by snow; 3) the difference between observed CR intensity and that calculated in point 2 will give the snow effect. This method can be used for any CR station that is covered at some periods by snow.

Coupling functions for NM total intensity and different multiplicities play important role when we by observed data of cosmic ray (CR) variations on the ground based detectors (mostly neutron monitors and muon telescopes) tried to determine the primary variations of CR energy spectrum out of the Earth"s atmosphere and magnetosphere, into interplanetary space. This is especially important for forecasting expected radiation hazards from solar CR, because by determined primary solar CR energy spectrum in the interplanetary space it is possible to determine effective time of solar CR ejection into solar wind, source function and the diffusion coefficient of solar CR propagation in space in dependence of particle energy and distance from the Sun. Coupling functions are important also for investigations of Forbush effect and precursory effects for forecasting dangerous interplanetary shock waves. We check obtained results for coupling functions by latitude expedition experimental data. We found how coupling functions depend from the level of solar activity and pressure on the level of observations. Obtained results are presented in the analytical forms that are convenient to use for any NM at any place on the Earth.

Coronal mass ejections (CMEs) and their interplanetary counterparts (ICMEs) propagate through the interplanetary medium and can modulate the intensity of galactic cosmic rays, resulting into non-recurrent Forbush decreases (FDs). In this work, we investigate the expected efficiency of CMEs as the modulator of GCRs resulting into a Forbush decrease (FD). We use specially processed data from the worldwide neutron monitor network (NMN) to pinpoint the characteristics of the recorded FDs together with CME related data from the detailed online catalog of SOHO/LASCO. Correlations of the FD magnitude to the CME initial speed, the ICME transit speed and the maximum solar wind (SW) speed are presented. Comparisons between the features of CMEs (mass, width, velocity) and the characteristics of FDs are also demonstrated. FD features for halo, partial halo and non halo CMEs is being displayed and discussed.

It will be visualized in real time CME clouds by means of the GMDN (Global Muon Detector Network). In addition the real time visualization of cosmic ray air showers on a planetarium dome in the DLR_School_Lab Bremen are shown. The relationship between cosmic ray muons and earthquakes will be sketched.

The neutron monitors measure data that are of great importance for the study of the solar activity and the prediction of the space weather. The last years, the neutron monitors have been organized in a network and their measurements are easily accessible to all the scientific community through the Neutron Monitor Database (NMDB). Several applications which make use of these measurements have been developed and provide with information about the cosmic rays and the prediction of the space weather. The knowledge of the interactions that take place in the atmosphere and inside the neutron monitor helps to determine the connection between the measurements of the neutron monitors and the cosmic ray particles that reach the earth. We present in this work a study of the interactions, based on Geant4 simulations, regarding the propagation of cosmic rays into the atmosphere and the detection procedure inside the neutron monitor.

The first Ground Level Enhancement (GLE) of solar cycle 24 was recorded on 17 May 2012. In this work we try to identify the acceleration source of energetic protons by combining in situ particle measurements from GOES 13, and solar cosmic rays registered by several NMs, as well as remote-sensing solar observations from SDO/AIA, SOHO/LASCO, and RHESSI. To this end, we derive the interplanetary magnetic field (IMF) path length and solar particle release time and we also present time-shifting analysis (TSA) for the first arriving particles that were detected at Earth by NMs. We demonstrate that the IMF direction was such that the NMs that were better connected, as derived by the particles asymptotic directions at 1-2.5 GV rigidity range, were Oulu (0.80 GV) and Apatity (0.65 GV) resulting into a prompt and fast rise in their counting rate. Furthermore, we discuss modeling results for GLE71 (i.e. spectrum, pitch-angle distribution and direction of anisotropy) obtained by the data made available via the Neutron Monitor Database (NMDB).

In the search for suitable precursors of solar events, the data from the neutron monitor at Dourbes, Belgium have been subjected to various deterministic and non-deterministic analyses. These analyses covered the entire available data from 1965 to 2013 and focused on examination of the data immediately before a Ground Level Enhancement and Forbush decrease events. In this work we report the results from this investigation and its application to a single-station model for prediction of solar events by ground based neutron monitors.

On January 20, 2005, 7:02–7:04 UT the Aragats Multidirectional Muon Monitor (AMMM) located at 3200 m registered enhancement of the high energy secondary muon flux (threshold ~5 GeV). The enhancement, lasting 3 min has statistical significance of ~4ó and was related to the X7.1 flare seen by the GOES, and very fast (>2500 km/s) CME seen by SOHO. Worldwide network of neutron monitors detects Ground Level Enhancements (GLE) #69 arriving very fast after flare; recovered energies of solar protons demonstrate rather hard spectra prolonged up to 10 GeV. The solar proton spectrum incident on the Earth's atmosphere was simulated and transport till AMMM detector located beneath 14 m of soil and concrete. The most probable minimal solar proton energy corresponding to the measured 5 GeV muon flux is ~25 GeV. On March 7, 2012 Large aperture telescope of Fermi gamma-ray observatory detected the ever highest energy gamma rays from the Sun with energy about 4 GeV. The minimal energy of the solar protons accelerated during the flare and producing 4 GeV gamma rays should be ~25 GeV. Thus, both measurements with secondary muons and gamma rays prove maximal energy of solar accelerators not smaller than 25 GeV.

Using the PLANETOCOSMICS simulation framework we simulated solar proton transport through the Earth's atmosphere and estimated angular and energy distributions of secondaries (protons, electrons, positrons, muons, photons and neutrons) at various atmospheric levels. As the source spectrum of solar protons at the boundary of atmosphere the spectra obtained with the GLE modeling from the data of neutron monitor network in a number events have been used. These Monte Carlo simulation results were compared with the available solar cosmic ray neutron monitor and balloon measurements. The calculated solar proton spectra are in good agreement with the balloon and neutron monitor observational data.