Observations of upper atmospheric optical flashes recorded from an aircraft

Abstract

Short‐duration upper atmospheric optical flashes were recorded on the night of 8 July, 1993 (9 July UT) from the NASA DC‐8 Airborne Laboratory flying over the American Midwest. All‐sky video images from an intensified silicon intensified target (ISIT) camera revealed 19 upper atmospheric flashes occurring over a period of ∼100 min. The flashes were similar in appearance to previously reported ground and shuttle‐based video observations. Detailed analysis of 12 of the events yielded these parameters: (1) duration ≤17 ms; (2) brightness 10–50 kR, roughly that of bright aurorae; (3) terminal heights 30–100 km, with a mean of ∼60 km; (4) horizontal extent 10–50 km; (5) emission volume >1000 km³. The relative frequency of the optical flashes was (6) 1:200–1:400 compared to negative cloud‐to‐ground discharges and 1:20–1:40 compared to positive cloud‐to‐ground discharges.

NOx from lightning: 1. Global distribution based on lightning physics

“…Although Borucki and Chameides [1984] Recently, upper atmospheric discharges have been discovered above thunderstorms at altitudes of 50-100 km [Sentman and Wescott, 1993;Lyons, 1994]. According to the Zel'dovich mechanism for NO production these discharges (known as "sprites") would produce little NO due to their low-energy densities and due to the low ambient pressure [Goldenbaum and Dickerson, 1993].…”

Sprites, Elves, and Glow Discharge Tubes

“…2 That same summer, Davis Sentman of the University of Alaska Fairbanks (UAF) sought to record the flashes from an aircraft flying over the Great Plains. 3 Within a day of each other, the two research teams had documented what turned out to be a common phenomenon in the mesosphere. In doing so, they initiated not only a new kind of continental-scale field experiment but also-and more important-a new interdisciplinary area of research.…”

Selected results from the ISUAL/FORMOSAT2 mission

“…More specifically, elves (Fukunishi et al 1996) span the altitudes of ~80 -90 km and are induced by the intense lightning electromagnetic pulse (EMP). Sprites, with a predominately-red luminous structure that spans ~40 -90 km (Sentman and Wescott 1993), are produced by the residual quasi-static electric field following an exceptionally strong cloud-to-ground (CG) lightning (Pasko et al 1997). Sprite halo, which shares the same generation mechanism with the sprite and centers around 70 km altitude (Barrington-Leigh et al 2001), can appear alone or accompanied by a sprite.…”