The lightning-sprite relationship
Abstract
Ongoing measurements have shown the relationship between lightning and sprites to be complex. To be sure, lightning discharges with large charge moment changes, which create a relatively strong electric field at mesospheric altitudes, do preferentially generate sprites. However, it is known experimentally that exceptionally few sprites are created by negative cloud-to-ground (CG) lightning, despite measurements showing similar occurrence rates between large +CG and -CG lightning in many circumstances [e.g., Huang et al., JGR, 1999]. This asymmetry is not understood. Moreover, an analysis of charge moment changes in many North American sprite-producing discharges during the summer of 2000 has indicated that similar discharges sometimes do and sometimes do not make sprites [Hu and Cummer, GRL, 2002], suggesting at a minimum some day to day variability in the ability of lightning to generate sprites. High speed video [Stenbaek-Nielsen et al., GRL, 2000] and ULF measurements [Fullekrug et al, JGR, 2001] have also documented the horizontal offset between the lightning channel and the sprite, indicating that sprites may not always initiate in the region of highest electric field. All of these facts suggest that factors other than lightning strength may play a role in the lightning-sprite relationship. Results from new analyses of lightning and sprite data from previous campaigns will be presented to address and shed new light on (though not necessarily solve) these important issues.
- Publication:
-
EGS - AGU - EUG Joint Assembly
- Pub Date:
- April 2003
- Bibcode:
- 2003EAEJA.....1751C