Video and Photographic Investigations of Lightning and Transient Luminous Events (TLEs) during PhOCAL 2014

A low-light camera system being ground tested for a rocket experiment in July, 1989 by Prof. John R. Winckler serendipitously captured by the first image of a sprite, the most common class of lightning-related transient luminous events [TLE], above a Minnesota thunderstorm. Since then a wide variety of cameras and optical sensors have played key roles in understanding the morphology of TLEs and providing objective measurements to validate theories as to their formation. Sprites are induced by exceptionally powerful CG lightning discharges, which themselves have been investigated for over a century using both still and video imagery. Rapid advances in sensor and camera technology during the past decade have created many opportunities to extend our understanding of TLEs and their parent lightning. During the 2014 summer campaign for the DARPA Physical Origins of Coupling to the Upper Atmosphere from Lightning (PhOCAL) project, various sensor systems were deployed. We focus on several dates during June - August 2014, in which excellent illustrations of the capabilities of these technologies were obtained. Around 0800 Z on 19 July 2014 a relatively small MCS moved through the Rapid City, SD area and its 3-D Lightning Mapping Array (LMA). A classic “jellyfish” sprite was captured by an intensified high-speed (10000 ips) Phantom camera in Ft. Collins, CO. Concurrently, the sprite parent +CG (SP+CG) was also imaged at 10000 ips by a Phantom deployed in a mobile van as part of the NSF-funded UPLIGHTS effort. A detailed analysis of the entire discharge process employs the images, NMQ gridded radar reflectivity data, the LMA VHF sources, NLDN and CMCN data, and VLF/ ELF retrievals of time dependent charge moment changes. This provides one of the most complete descriptions of sprite phenomenology to date. This same night, a modest MCS in northeastern NM also produced a number of highly photogenic sprites. These were captured by multiple low-light Watec 902H U cameras, as well as detailed color images using a Nikon D4S. Special DSLR cameras with their IR cut filters removed also can capture sprites, and in addition, convectively-generated gravity waves in the airglow layer near the mesopause. These waves play a key role in middle-atmosphere dynamics, but also modulate the luminosity of elves and possible sprites. Observations with color-near infrared ground based cameras coordinated with the Day/Night Band (DNB) sensor on the new Suomi NPP satellite are revealing that CGGWs are far more common over the central US during the convective season than once thought.