Simultaneous Observations of Mesospheric Gravity Waves and Sprites Generated by a Midwestern Thunderstorm
Abstract
The present report investigates using simultaneous observations of coincident gravity waves and sprites to establish an upper limit on sprite-associated thermal energy deposition in the mesosphere. The University of Alaska operated a variety of optical image's and photometers at two ground sites in support of the NASA Sprites99 balloon campaign. One site was atop a US Forest Service lookout tower on Bear Mt. in the Black Hills, in western South Dakota. On the night of 18 August 1999 we obtained from this site simultaneous images of sprites and OH airglow modulated by gravity waves emanating from a very active Sprite producing thunderstorm over Nebraska, to the Southeast of Bear Mt. Using 25 s exposures with a bare CCD camera equipped with a red filter, we were able to coincidentally record both short duration (< 10 ms) but bright (>3 MR) N2 1PG red emissions from sprites and much weaker (-1 kR), but persistent, OH Meinel nightglow emissions. A time lapse movie created from images revealed short period, complete 360 degrees concentric wave structures emanating radially outward from a central excitation region directly above the storm. During the initial stages of the storm outwardly expanding waves possessed a period of r =10 min and wavelength lamda = 50 km. Over a 1 h interval the waves gradually changed to longer period r =11 min and shorter wavelength lamda =40 km. Over the lull 2 h observation time, about two dozen bright sprites generated by the underlying thunderstorm were recorded near the center of the outwardly radiating gravity wave pattern. No distinctive OH brightness signatures uniquely associated with the sprites were detected at the level of 2% of the ambient background brightness, establishing an associated upper limit of approximately DeltaTau<- 0.5K for a neutral temperature perturbation over the volume of the Sprites.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 2003
- Accession Number
- ADA437749
Entities
People
- D. D. Sentman
- D. R. Moudry
- E. M. Dewan
- E. M. Wescott
- F. T. Sabbas
- H. C. Stenbaek-nielsen
- J. Morrill
- M. J. Heavner
- R. H. Picard
Organizations
- University of Alaska Fairbanks