Abstract
Severe weather forecasting is an important tool for mitigating damages
brought by intense lightning, large hail, heavy precipitation, strong
winds, or tornadoes during thunderstorms, yet the reliability of such
forecasts suffers from our limited understanding of the severe weather
generative processes inside thunderclouds. With an increasing knowledge
of the occurrence context of distinct types of lightning within storms,
lightning remote sensing may elucidate the kinematic and microphysical
environment where severe weather initiates. In particular, distinct
energetic intra-cloud (IC) lightning discharges, compact intra-cloud
lightning discharges [CID; e.g., Nag and Rakov, 2010] and energetic
intra-cloud pulses [EIP; e.g., Lyu et al., 2015], have been shown to
have different occurrence contexts, making them strong candidates for
thunderstorm remote sensing research. In this study, observations from
the RELAMPAGO field campaign in Argentina (November 1 to December 12th
2018) are used to determine lightning flash rates and the prevalence of
different energetic lightning types in RELAMPAGO storms, enabling
further research on the link between lightning activity and severe
weather production inside thunderstorms.Lightning events during
RELAMPAGO were observed by a deployed array of four Low-Frequency (LF,
~1-400 kHz) radio receivers. Using time of arrival,
magnetic direction finding, and peak amplitude for each observed event
at different stations, lightning source locations are estimated using a
statistical least squares filter, along with clock and site errors
associated with the receivers. Return stroke peak current for each event
is also estimated in the filter, using an atmospheric attenuation
observation model. The energetic lightning events in the campaign are
then classified automatically between cloud-to-ground (CG), IC, CID or
EIP, following an improved parametrization scheme originally proposed by
Lyu et al. [2015]. In this paper we present the geolocation and
classification of RELAMPAGO lightning events, and we also provide an
analysis of lightning flash rates during the campaign. A few individual
thunderstorm case studies are also discussed, which are augmented by
other meteorological data from dual-polarimetric radar, hailpads, and
other sources.