HR: 0800h
AN: AE21A-0983    [Abstracts]
TI: Evidence for Synchronicity of Lightning Activity in Spatially Remote Thunderstorms Obtained from Space Shuttle Observations
AU: * Yair, Y
EM: yoavya@openu.ac.il
AF: The Open University of Israel, P.O. Box 808, Ra'anana, 43107 Israel
AU: Aviv, R
EM: aviv@openu.ac.il
AF: The Open University of Israel, P.O. Box 808, Ra'anana, 43107 Israel
AU: Ravid, G
EM: giladra@openu.ac.il
AF: The Open University of Israel, P.O. Box 808, Ra'anana, 43107 Israel
AU: Yaniv, R
EM: royya@012.net.il
AF: The Open University of Israel, P.O. Box 808, Ra'anana, 43107 Israel
AU: Ziv, B
EM: baruchz@openu.ac.il
AF: The Open University of Israel, P.O. Box 808, Ra'anana, 43107 Israel
AU: Price, C
EM: cprice@flash.tau.ac.il
AF: Tel-Aviv University, Ramat-Aviv, Tel-Aviv, 69978 Israel
AB: Visual observations by space shuttle astronauts detailed a phenomenon in which spatially distant thunderstorm cells seemed to reciprocally "ignite" lightning flashes in a semi-cyclic sequence. We report the quantitative analysis of lightning observations conducted within the framework of the MEIDEX-sprite campaign on board the space shuttle Columbia in January 2003 [Yair et al., 2003]. We analyzed video footage of 6 storm systems with varying flash rates, which occurred over Africa, South America, Australia and the Pacific Ocean. It is found that when the storm flash rate was high, lightning activity in horizontally remote electrically active cells became clustered, with bursts of nearly simultaneous activity separated by periods of quiet. The recurrence time was ~2.5 seconds, close to the time delay between consecutive signals in the SR range previously reported [Fllekrug, 1995]. We propose that this behavior is similar to the collective dynamics of a network of weakly coupled limit-cycle oscillators [Strogatz, 2000]. Thunderstorm cells embedded within a mesoscale convective system (MCS) constitute such a network, and their lightning frequency is best described in terms of phase-locking of a globally coupled array [Kourtchatov et al., 1995]. The dominant network hub in such an MCS is the thunderstorm cell with the highest flash rate, which affects the lightning activity of neighboring cells. Comparison of basic parameters of the lightning network with predictions of random graph models reveals that the network cannot be described by the classical random graph model [Erdos and Renyi, 1960], but is more compatible with generalized random graphs with prescribed degree distribution [Newman et al., 2001] that exhibit a high clustering coefficient and small average path lengths. Such networks are capable of supporting fast response, synchronization and coherent oscillations. Several physical mechanisms are suggested to explain this phenomenon.
DE: 3304 Atmospheric electricity
DE: 3324 Lightning
SC: Atmospheric and Space Electricity [AE]
MN: Fall Meeting 2005