A New Approach for Lightning Infrasound Detection Using Ground and Balloon-Based Instruments

Date: 4/26/2019

Time: 06:00 PM

Room: Fifth Avenue

Infrasound recorded by airborne and ground-based instruments can be used cooperatively to locate and identify acoustic signals generated by events of unknown source location. A linear inversion method for determining the azimuth and source location of an infrasound signal is presented as an alternative to Progressive Multi-Channel Correlation (PMCC) [Cansi, 1995]. This method estimates both azimuth and inclination of incoming plane waves at a sensor array, mitigating some limitations presented by the PMCC algorithm. These methods are applied to events detected (1.4-3.3Pa) during a nearby (30-500km north) storm (data acquired from WWLLN) by the ground-based IMS station IS36 in Chatham Islands, New Zealand on May 24, 2016. Source to receiver raypaths are used to estimate the infrasound travel times at the IS36 array. The travel time estimates correlate to 6 ground station arrivals, suggesting that the detections are storm-generated. Plane wave inversions indicate that the events originate from azimuths ranging -14 to 9 degrees from North with inclinations ranging 43 to 56 degrees from horizontal, further supporting the source locations. A total of 9 events detected by a balloon-borne infrasound microphone (Bowman & Lees, 2016; Lamb et al., 2018) traveling at mid-stratospheric altitudes approximately 445km southwest of the IS36 array will be presented as candidates for secondary lightning detections.

Presenting Author: Julian W. Traphagan

Authors