HR: 08:42h
AN: AE51A-04 INVITED     [Abstracts]
TI: Observations of Sprites and Elves with the ISUAL Array Photometer
AU: * Fukunishi, H
EM: fuku@pat.geophys.tohoku.ac.jp
AF: Department of Geophysics, Tohoku University, Aramaki-aoba, Sendai, 980-8578 Japan
AU: Takahashi, Y
EM: yukihiro@pat.geophys.tohoku.ac.jp
AF: Department of Geophysics, Tohoku University, Aramaki-aoba, Sendai, 980-8578 Japan
AU: Adachi, T
EM: adachi@pat.geophys.tohoku.ac.jp
AF: Department of Geophysics, Tohoku University, Aramaki-aoba, Sendai, 980-8578 Japan
AU: Hsu, R
EM: rrhsu@phys.ncku.edu.tw
AF: Physics Department, National Cheng Kung University, Ta-Hsueh Road, Tainan, 701 Taiwan
AU: Su, H
EM: htsu@phys.ncku.edu.tw
AF: Physics Department, National Cheng Kung University, Ta-Hsueh Road, Tainan, 701 Taiwan
AU: Chen, A B
EM: alfred@phys.ncku.edu.tw
AF: Physics Department, National Cheng Kung University, Ta-Hsueh Road, Tainan, 701 Taiwan
AU: Mende, S B
EM: mende@ssl.berkeley.edu
AF: Space Sciences Laboratory, University of California at Berkeley, Gauss Way , Berkeley, CA 94720 United States
AU: Frey, H U
EM: hfrey@apollo.ssl.berkeley.edu
AF: Space Sciences Laboratory, University of California at Berkeley, Gauss Way , Berkeley, CA 94720 United States
AU: Lee, L
EM: loulee@nspo.gov.tw
AF: National Space Program Office, Science-based Industrial Park, Hsinchu, 30077 Taiwan
AB: The ROCSAT-2 satellite with a scientific payload named ISUAL and a remote sensing payload was launched on May 20, 2004 from the Vandenberg range in California. The ISUAL (Imager of Sprites/Upper Atmospheric Lightning) instrument is composed of an imager, a spectrophotometer, and an array photometer. The ISUAL project is an international collaboration of National Cheng Kung University and National Space Program Office in Taiwan, University of California in USA, and Tohoku University in Japan. The goals of ISUAL are to complete a global survey of transient luminous events (TLEs: sprites, elves, blue jets, gigantic jets etc.) and also to investigate the global distributions of airglow and aurora and their dynamical processes. The ISUAL instrument observes optical emissions at the limb of the Earth with a range of 3373 km to the limb at the 60 km altitude tangent point. The array photometer developed by the Tohoku University group can capture spatial and temporal evolution of TLEs at the two wavelength ranges of 370-450 and 530-650 nm selected by blue and red filters, ewspectively. Each photometer consists of 16 channels arrayed in vertical with a field of view of 0.23 degrees (vertical) by 22.5 degrees (horizontal). The vertical resolution of 0.23 degrees corresponds to about 11 km at the limb. The array photometer is operated in an event trigger mode for TLE measurement. The length of data for one event is 220 ms, and the sampling frequency is 20 kHz for the first 18 ms and 2 kHz for the following 202 ms. The ISUAL has been operated on a routine basis from the middle of July in 2004. The total number of lightning cloud flashes measured by the ISUAL for 40 days from the middle of July to the end of August is 2210, while the numbers of sprites and elves for the same period are 20 and 100, respectively. A high time resolution (50 microseconds) and a high vertical resolution (11 km) of the array photometer enable us to investigate rapid intensity variations of sprites and elves as a function of altitude. Furthermore, blue/red intensity ratio measurements at 16 channels enable us to estimate the energies of electrons inducing optical emissions as a function of altitude. Typical examples of sprites and elves captured by the array photometer are presented, and their space-time structures and spectral features are discussed.
DE: 3324 Lightning
DE: 3334 Middle atmosphere dynamics (0341, 0342)
DE: 3304 Atmospheric electricity
DE: 0342 Middle atmosphere--energy deposition
SC: Atmospheric and Space Electricity [AE]
MN: 2004 AGU Fall Meeting