A particular strength of lightning remote sensing is the variety of lightning types observed, each with a unique occurrence context and characteristically different emission. Distinct energetic intra-cloud (EIC) lightning discharges – compact intra-cloud lightning discharges (CIDs) and energetic intra-cloud pulses (EIPs) – produce intense RF radiation, suggesting large currents inside the cloud, and they also have different production mechanisms and occurrence contexts. A Low-Frequency (LF) lightning remote sensing instrument array was deployed during the RELAMPAGO field campaign in west central Argentina, designed to investigate convective storms that produce high-impact weather. LF data from the campaign can provide a valuable dataset for researching the lightning context of EICs in a variety of sub-tropical convective storms. This paper describes the production of an LF-CID dataset in RELAMPAGO, and includes a preliminary analysis of CID prevalence.
Geolocated lightning events and their corresponding observed waveforms from the RELAMPAGO LF dataset are used in the classification of EICs. Height estimates based on skywave reflections are computed, where pre-fit residual data editing is used to improve robustness against outliers. Even if EIPs occurred within the network, given the low number of very high peak current events and receiver saturation, automatic classification of EIPs may not be feasible using this dataset. The classification of CIDs, on the other hand, is straightforward and their properties, for both positive and negative polarity, are investigated. A few RELAMPAGO case studies are also presented, where high variability of CID prevalence in ordinary storms and high-altitude positive CIDs, possibly in overshooting tops, are observed.