The Relation Between Lightning and Isolated Impulsive >30 keV Electron Precipitation Events

Tuesday, 16 December 2014
Michael McCarthy1, Gregory S Bowers2, Robert H Holzworth II1 and Robyn M Millan3, (1)University of Washington Seattle Campus, Seattle, WA, United States, (2)Univ of California Santa Cruz, Santa Cruz, CA, United States, (3)Dartmouth College, Hanover, NH, United States
Isolated impulsive (few seconds time scale) magnetospheric losses of >30 keV electrons to the upper atmosphere have been inferred from bremsstrahlung observations on stationary stratospheric balloon platforms. As a first step to understanding the mechanism for this phenomenon, we address the question: what is the relation between impulsive electron precipitation events and lightning strokes? Two recent developments permit progress on this question, global lightning location networks that precisely locate and time lightning strokes, and the BARREL mission's acquisition of over 9000 hours of stratospheric bremsstrahlung observations. The analysis consists of identifying impulsive electron precipitation events in BARREL's bremsstrahlung record and relating those to immediately prior lightning strokes, with consideration for lightning network detection efficiency. A strong relation between impulsive precipitation events and lightning implies a primary role of the previously studied lightning-induced electron precipitation phenomenon. A weak relation implies another unrecognized mechanism is responsible for these isolated impulsive events. Understanding the conditions, mechanisms, and extent of isolated impulsive electron loss events is a part of an overall goal to comprehend magnetospheric trapped electron population variability.