Conveners:
Mike Taylor, Utah State University, (mtaylor@cc.usu.edu),
Mark Stanley, Los Alamos National Laboratory, (stanleym@lanl.gov)
2004 Monday 28 June 0100-0300 PM
The session was well attended with about 50 attendees. The session began with a tribute to Les Hale, who passed away on December 26, 2003. Les was the principal investigator on over 100 sounding rocket flights and made numerous contributions to our understanding of the conductivity and composition of the middle atmosphere. Les was highly influential to many other research topics such as the global electric circuit, waveguide propagation, and electromagnetic interference, to name a few.
The main thrust of presentations and discussions for the workshop were divided into two main areas:
The energetic lightning discharges which produce sprites can cause the entire earth-ionosphere cavity to oscillate at the Schumann Resonance frequencies. Heng Yang (Penn State) showed with his model how these frequencies are modified by X-ray bursts and Solar Proton Events (SPEs). Laurie Triplett (Los Alamos National Laboratory) used a model to predict when the sprite-producing discharges would produce runaway beams and/or narrow streamers as well as the intensities of the optical emission lines. There was active discussion afterwards about whether sprites ever exist without fine structure in the form of streamers. Ningyu Liu (Penn State) showed results from his streamer model which he has used to predict streamer parameters such as the minimum propagation field, velocity, dimensions, and decay, to name a few.
William Beasley (Oklahoma University) discussed the very recent research campaign which was conducted from May 13 to June 21 in association with the TELEX experiment based out of Oklahoma. Aaron Musfeldt looked for sprites with low-light level cameras at night while instrumented balloons were flown with X-ray detectors both within and above storms. They are just beginning to process the data and are seeking collaborations with others who may have relevant data during the time period of interest.
The future research campaigns which were discussed could also benefit from collaborations and the infusion of additional data sources. Stephen Mende (University of California, Berkeley) discussed two projects, SOCRATES and ISUAL, the latter of which had just started collecting data from space on sprites, elves, and lightning. The SOCRATES experiment will hopefully take place in July of 2005 with balloon-based electric field probes acquiring data above sprite-producing storms over the Great Plains while video of sprites are acquired at various sites. Mark Stanley (Los Alamos National Laboratory) gave an overview of the sprite campaign to be conducted at Langmuir Laboratory in mid-July and August 4-21 by researchers from Stanford and elsewhere. Hans Stenbaek-Nielsen (University of Alaska, Fairbanks) discussed his high-speed spectral imaging experiment which will be deployed in August at Langmuir and will attempt to resolve whether sprite processes are important for the physics and chemistry of the mesosphere. Mike Taylor (Utah State University) discussed the second Brazil campaign, which is slated to take place in February and November of 2005 and will utilize balloons outfitted with X-ray detectors.
At the end of the session, there was active discussion about key issues in our field. The initiation of sprites as well as the transition of some sprites from a column to a carrot appearance were identified as two main scientific problems which need to be tackled. The need for more spectral information on the development of sprites was stated as being essential data in discriminating between some competing theories. It was also stressed by one member that in order to get more funding, we need to emphasize issues which are more than just scientifically interesting and have some practical or far-reaching importance as well.