Investigations on Atmospheric Acceleration of Energetic

Electrons by ERG and SCOPE

Wing-Huen IpInstitutes of Space Science and Astron

omyNational Central University

March 17, 2009

Outline

• TGFs• TLEs• Saturn: Extreme Electrostatic Charging • Jupiter: Recirculation Process of MeV Elec

trons • Earth: The Russel-McPherron Effect• Space Weather

Terrestrial Gamma-ray Flashes (TGFs)

Terrestrail Gamma-ray Flashes:CGRO-BATSE Observations

• NASA Compton Gamma-ray Observatory (CGRO) BATSE detected atmospheric gamma-ray bursts at 10’s MeV (Fishman et al. 1994)

• Close association with thunderstorm and lightning activity (Inan et al., 1996)

• Events lasted for a few mseconds to few tens of mseconds

Fishman et al., Science, 264, 1313, 1994

RHESSI observations of TGFs

• RHESSI showed seasonal and geographic correlation of TGFs with lightning hot spots (Smith et al., 2005)

Smith et al., Science, 307, 1085, 2005

• ~17% of TGFs detected by CGRO/BATSE have been reclassified to be 30 MeV electrons/positrons (Dwyer et al., 2008)

Smith et al., Science, 307, 1085, 2005

Theory

• Relativistic runaway electron beams driven upward by intense QE field following positive cloud-to-ground discharges (Gurevich et al., Phys. Lett., A, 165, 463, 1992)

• DC electric field ~ potential drop of about 30 MV (Tonev and Velinov, Adv. Space Res., 31, 1443, 2003)

Transient Luminous Events(LTEs)

First color image of a sprite

http://sprite.phys.ncku.edu.tw/new/news/0626_presss/big_red_sprites_sentman_s.jpg

Valdivia et al., GRL, 24, 3169, 1997

Trapped relativistic electrons from lightning

Lehtinen et al., GRL, 27, 1095, 2000

Saturnian rings

Formation of radial spokes

Jones, et al. GRL, 33, L21202, 2006.

Jones, et al. GRL, 33, L21202, 2006.

Jovian synchrotron radiation

http://www.atmos.ucla.edu/~bhattach/sr.gif

Recirculation Model of Jovian Electrons

Nishida, JGR, 81, 1771, 1976

Fujimoto and Nishida, JGR, 95, 3840, 1990

Earth’s magnetosphere

http://farm4.static.flickr.com/3097/3128294877_2558320fbc.jpg

Fujimoto and Nishida, JGR, 95, 4265, 1990

The Russell-McPherron Effect

Russell and McPherron, JGR, 78, 92, 1973

Spacecraft charging

http://sd-www.jhuapl.edu/UPOS/SCA/spacecraft-charging-assessment-final-report.pdf

Thanks