During November 2018–April 2019, an 11-station very high frequency (VHF) Lightning Mapping Array (LMA) was deployed to Córdoba Province, Argentina. The purpose of the LMA was validation of the Geostationary Lightning Mapper (GLM), but the deployment was coordinated with two field campaigns. The LMA observed 2.9 million flashes (≥ five sources) during 163 days, and level-1 (VHF locations), level-2 (flashes classified), and level-3 (gridded products) datasets have been made public. The network’s performance allows scientifically useful analysis within 100 km when at least seven stations were active. Careful analysis beyond 100 km is also possible. The LMA dataset includes many examples of intense storms with extremely high flash rates (>1 s−1), electrical discharges in overshooting tops (OTs), as well as anomalously charged thunderstorms with low-altitude lightning. The modal flash altitude was 10 km, but many flashes occurred at very high altitude (15–20 km). There were also anomalous and stratiform flashes near 5–7 km in altitude. Most flashes were small (<50 km2 area). Comparisons with GLM on 14 and 20 December 2018 indicated that GLM most successfully detected larger flashes (i.e., more than 100 VHF sources), with detection efficiency (DE) up to 90%. However, GLM DE was reduced for flashes that were smaller or that occurred lower in the cloud (e.g., near 6-km altitude). GLM DE also was reduced during a period of OT electrical discharges. Overall, GLM DE was a strong function of thunderstorm evolution and the dominant characteristics of the lightning it produced.

 A new automated method to estimate the polarity, altitude, and vertical depth of charge layers from flashes is presented. Thunderstorm charge structures in Central Argentina are characterized from months of LMA data, with 13.3% anomalous charge structure. Cordoba anomalously charged thunderstorms have a distinct charge altitude distribution when compared to those in Colorado.

The Córdoba Argentina Marx Meter Array (CAMMA), consisting of 10 second-generation Huntsville Alabama Marx Meter Array (HAMMA 2) sensors, operated at Córdoba, Argentina, during the Remote sensing of Electrification, Lightning, And Mesoscale/microscale Processes with Adaptive Ground Observations (RELAMPAGO) field campaign in late 2018. Initial results obtained from the campaign demonstrate that the new sensor is able to provide a significantly more detailed depiction of various lightning processes than its first generation. The lightning flashes mapped by the CAMMA and a colocated Lightning Mapping Array (LMA) were compared. The overall flash structures mapped by the CAMMA and the LMA look similar for most of the flashes. However, comparisons at smaller time scale show that the majority of CAMMA and LMA sources are not concurrent, indicating that unmatched sources were possibly due to different physical processes in leader propagation dominating different frequencies and differences in data processing and location techniques.

Previous studies have shown that subsequent leaders in positive cloud‐to‐ground lightning (+CG) flashes rarely traverse pre‐existing channels to ground. In this paper, we present evidence that this actually can be common, at least for some thunderstorms. Observations of +CG flashes in a supercell storm in Argentina by Córdoba Argentina Marx Meter Array (CAMMA) are presented, in which 54 (64%) of 84 multiple‐stroke +CG flashes had subsequent leaders following a pre‐existing channel to ground. These subsequent positive leaders are found to behave similarly to their negative counterparts, including propagation speeds along pre‐existing channels with a median of 8 × 106 m/s, which is comparable to that of negative dart leaders. Two representative multiple‐stroke +CG flashes are presented and discussed in detail. The observations reported herein call for an update to the traditional explanation of the disparity between positive and negative lightning.

Past studies have associated the severity of thunderstorms with patterns in charge distribution Wiens et al., 2005). The dominant meteorological environment provides initial conditions that would influence the kinematics and microphysics within thunderstorms, which in turn affects its charge structure and dominant cloud-to-ground lightning (CG) polarity. Relatively few studies have documented the charge structure over continents other than North America (López et al., 2019;Pawar & Kamra, 2004;Pineda et al., 2016;Qie et al., 2005). Therefore, documenting charge structures of storms in regions such as Argentina, which has some of the highest flash rates in thunderstorms in the world (Zipser et al., 2006), is of interest for develop a more robust understanding of global storm charge structures.Due to the nature of lightning processes and their characteristic emission in the very-high frequency (VHF) spectrum, thunderstorm charge structures associated with flashes can be inferred from Lightning Mapping Array (LMA) observations (Lang & Rutledge, 2011;Rust et al., 2005;Wiens et al., 2005). Based on knowledge of radiation propagation by lightning, VHF-based sensors primarily detect radiation from negative breakdown of lightning that propagates through regions of positive charge (Mazur & Ruhnke, 1993;Rison et al., 1999). Then, mapping of VHF sources is used to manually determine the location of positive and negative charge layers (