TEPA 2010 conference considered manifestations of the Relativistic Runway ElectronAvalanche (RREA) process on Earth Surface in Atmosphere and in Space.

The Thunderstorms and Elementary Particle Acceleration (TEPA-2010) conference was held from September 6 through 11,  2010 in the Nor Amberd international conference centre of Artem Alikhanyan National Laboratory (AANL), formerly known as Yerevan Physics Institute,  in Armenia.

The conference was organized by the Cosmic Ray Division (CRD) of AANL, Armenia and Skobeltsyn Institute of Nuclear Physics of Moscow State University, Russian Federation.   The conference was sponsored by AANL, COSPAR and the Armenian state science committee. Forty scientists and students listened to 37 original talks and lectures on the following subjects:
•    Surface measurements of the electrons, muons, neutrons and gamma rays from the RREA process (thunderstorm ground enhancements – TGEs)
•    Terrestrial gamma-ray flashes (TGFs) observed by gamma-ray observatories on-orbit;
•    Broadband electromagnetic signals detection from thunderstorms and extensive air showers(EAS);
•    Transient luminous effects(TLE) in the upper atmosphere;
•    Relativistic runaway electron avalanche (RREA) process (simulations, theory);
•    Cosmic rays and space weather issues.
The Relativistic Runaway Electron Avalanche (RREA) phenomena was considered for the first time by all its manifestations, including:
•    Electron, gamma ray and neutron fluxes originated by the RREA process in the thunderclouds and measured by the variety of particle detectors operating at the cosmic ray research stations on Mt. Aragats (Armenia) and Baksan valley ( Russian Federation);
•    Gamma-ray and electron-positron flashes observed with the orbiting Fermi-gamma-ray burst monitor (GBM);
•    Radio-emission from lightning detected by the LOPES experiment measuring radio signals of particle air showers and lightning (Germany) and LASS project at the Pierre Auger Observatory (Argentina);
•    UV (240-400 nm) and IR (600-800 nm) radiation flashes observed onboard "Tatiana -1 and "Tatiana-2" satellites (Moscow State University, Russian Federation).

Real-time monitoring of the particle fluxes by space-born and ground-based detectors both point to the same RREA origin of TGFs and TGEs.  Two types of RREA events were detected on Mt. Aragats: short (~1µsec, inverse TGFs) and long (lasting hours, thunderstorm ground enhancements - TGEs). The seed particles for the TGFs are probably generated in intercloud lightning (IC); and for TGEs the seed particles come from the ambient population of secondary MeV energy electrons due to EAS. The proportion of short events was ~0.1% of the entire 8-minute enhancement detected on  September 19, 2010. Energy spectra of TGEs detected at Aragats in 2009 and 2010 confirm the simulation studies that the electron energy spectrum has exponential shape and gamma-ray – power law shape. Both spectra for the largest  September 19, 2009 event extend up to 45-50 MeV.
Huge fluxes of electrons, positrons, gammas and neutrons near the Earth’s surface are undoubtedly newly discovered global physical phenomena that should be studied by experimental and theoretical methods. Particle acceleration and multiplication and broad bandwidth electromagnetic emissions associated with thunderstorms trigger various dynamic processes in the chain atmosphere-ionosphere, causing global geo-effects. The huge values of energy (up to several gigajoules in an impulse) measured by the Tatiana satellites, demonstrate the importance of the research of the atmosphere-ionosphere energy chain and draw attention to the upper atmospheric discharges, which are dangerous for high–altitudes flights.  Precise muon detector developed by the National nuclear university (MEPHI) is maybe the first instrument providing data both for the space weather forecasting and meteorology. Simultaneous disturbances of the muon flux and geomagnetic field detected at Baksan point to particle-field interactions in the upper atmosphere. The amplification of the radio frequency electric field signals from EAS during a thunderstorm can lead to the modulation of the EAS size spectra and, consequently, to the possible estimation of the intercloud electric fields by radio measurements.
However, we have to remember that the sun is the driving force of processes in the atmosphere, ionosphere and magnetosphere. Therefore, the full chain (solar-terrestrial system) includes the solar wind, magnetosphere, ionosphere and atmosphere. The system is influenced by the radiation from the sun and flux of solar and galactic cosmic rays. The radiation environment near the earth and plasma-geomagnetic field interactions constitutes the space weather conditions. Space weather influences the terrestrial climate and natural hazards, although the mechanisms of space weather effects on the Earth are far from being explained and many aspects of solar activity itself are still unclear. These effects can be understood and quantitatively estimated only by studying the solar-terrestrial system in its entirety: identification of the solar agents affecting the Earth, understanding their occurrence and evolution, and the mechanisms of solar energy transfer all the way from the sun to the earth. This requires integration of all existing information and specific knowledge now spread in many different scientific areas: solar physics, solar wind, cosmic rays, interplanetary space, magnetosphere, and ionosphere, upper, middle and lower atmosphere.

The new effects explored and discussed during the TEPA-2010 conference, the inverse flux of huge energy from the upper atmosphere to the ionosphere and even to the magnetosphere, should be considered as integral component of the solar-terrestrial connections. Therefore, the investigation of the RREA process has enormous importance for understanding global change, dynamics and evolution of the terrestrial climate and natural hazards.

The goals of the research could be achieved only within broad multidisciplinary cooperation, integrating its observational, research and modelling capacities. The participants of the conference agreed to cooperate to install various sensors, measuring particle fluxes, transient luminous events, broadband radio emission and radiation, on the earth’s surface and onboard orbiting satellites.

All participants visited the high altitude Aragats cosmic ray research station in Armenia and saw various particle detectors in operation, aimed for investigating space weather and RREA process. New field meters and lightning detectors installed on the slopes of Mt. Aragats will allow better understanding of the RREA process, space weather, solar-terrestrial connections and its influence on the climate.

Among TEPA participants were 10 PhD students. The lectures of Arnold Wolfendale on climate change and possible influence of cosmic rays on origin of live; Anatoly Petrukhin on the new explanation of the shape of high energy cosmic ray energy spectra; and - Razmik Mirzoyan on the history and future of the Cherenkov gamma ray astronomy  fascinated the students. 

The conference presentations are available on the CRD site: http://crd.yerphi.am/Conferences/tepa2010/Presentations_
Conference proceedings will be available in early 2011.