Optical observations of transient luminous events associated with winter thunderstorms near the coast of Israel
Authors:Yair, Yoav Price, Colin Ganot, Michal Greenberg, Eran Yaniv, Roy Ziv, Baruch Sherez, Yosef Devir, Adam Bor, Jo'zsef Satori, Gabriella
Volume:91
DOI:10.1016/j.atmosres.2008.06.018
Published:2009
Document Type:Article; Proceedings Paper
Abstract:We report the results of two observation campaigns conducted during the Northern Hemisphere winters of 2005-6 and 2006-7 aiming to detect transient luminous events (TLEs) above winter thunderstorms in the vicinity of Israel and the eastern coastline of the Mediterranean Sea. In 10 out of 31 different observation nights we detected 66 events: 56 sprites and 10 Elves. The detection ranges varied from 250 to 450 km. Sprites were found to be produced by active cells with a vertical dimension of 5-9 km and cloud top temperature similar to-40 degrees C, embedded in a much larger matrix of stratiform precipitating cloudiness. This configuration closely resembles the conditions for winter sprites in the Hokuriku region of Japan. Synchronized with the optical observations, ELF data were recorded at two observation stations in Israel and Hungary in order to qualify and quantify parameters of the parent lightning discharge associated with the TLEs. These stations are located 500 km and 2100 km respectively from the Eastern Mediterranean Sea, where most TLEs occur. Among the optically observed TLE events, we found that all the ELF signals were produced solely by positive cloud-to-ground flashes (+CGs), most of which were recorded in Israel (88%) and Hungary (77%). Calculation of the Charge Moment Change showed average values of 1400 600 C km, with some extreme events exceeding 3500 C km. The average time delay between the ELF transient of the parent+CG and the observed sprites was 55 ms, with shorter delays for column sprites (42+/-34 ms) compared to carrot sprites (68+/-34). Furthermore, based on the ELF data, there were no early identifiable precursors to TLE occurrence in the regional lightning activity. From the spatial formation of the observed columniform sprites, we propose that columniform sprites are sometimes arranged in a 3-dimensional circular pattern, thus mapping the instantaneous electric field in the mesosphere. (C) 2008 Published by Elsevier B.V.
Author Information
Corresponding Author:Yair, Y (通讯作者)，Open Univ Israel, Dept Life & Nat Sci, Ctr Technol Distance Educ, 108 Ravutski St,POB 808, IL-43107 Raanana, Israel.
Reprint Address:Yair, Y (通讯作者)，Open Univ Israel, Dept Life & Nat Sci, Ctr Technol Distance Educ, 108 Ravutski St,POB 808, IL-43107 Raanana, Israel.
Addresses:[Yair, Yoav] Open Univ Israel, Dept Life & Nat Sci, Ctr Technol Distance Educ, IL-43107 Raanana, Israel; [Price, Colin; Ganot, Michal; Greenberg, Eran; Yaniv, Roy; Sherez, Yosef] Tel Aviv Univ, Dept Geophys & Planetary Sci, IL-69978 Tel Aviv, Israel; [Bor, Jo'zsef; Satori, Gabriella] Hungarian Acad Sci, Geodet & Geophys Res Inst, Sopron, Hungary
E-mail Addresses:yoavyair@yahoo.com