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Charge structure derived from lightning leader development of tropical thunderstorms comprising equatorial latitudes of less than ±10° has not been investigated yet. In this work, using a lightning mapping array installed in northern Colombia, the charge structure, lightning leader initiations, and the cloud‐to‐ground strokes rates of two thunderstorms have been analyzed. Additionally, radar information is also included. The identification of the charge regions has been obtained by analyzing the propagation of lightning leader developments. Flashes initiate between 4‐ and 15‐km altitude. High initiation rates are different in the two storms. In one case the high rates are found between 8 and 13 km. In the other case, the initiation heights are found between 10 and 15 km. The storms show typical tripolar charge structure where the upper positive charge is present at 10 to ~15 km, the midlevel negative charge is found between 6 and 9 km, and the lower positive charge between 4 and 6 km altitude. Intracloud lightning flashes with inverted polarity have been identified for short period. In other periods, screening layer flashes have been detected at 14–15 km. The overall results show that the charge structures in the two Colombian storms are similar to the structures reported in North Central Florida, but with the significant difference that the flash initiation altitudes  are 2 km higher in Colombia. The vertical configuration of the charge regions and the leader development of these thunderstorms may help explain the occurrence of terrestrial gamma‐ray flashes in tropical thunderstorms.

Liver transplantation (LT) is an established treatment for children with acute and chronic liver failure. Some reports suggest that infants under the age of 1 yr and children weighing under 13 kg are high-risk groups associated with less satisfactory results. This report describes our experience during the pediatric intensive care unit stay of 16 infants weighing <7 kg who received LT. We reviewed the records of 16 infants with median age 7.4 months and median weight 5.8 kg, who received 18 liver allografts, nine whole and nine reduced. We also reviewed the use of adrenergic agonist agents, anti-infectious agents, antihypertensive agents, diuretics, immunosuppression protocol, sedation-analgesia agents, others agents (prostaglandin E(1), heparin and dipyridamole), diagnosis and management of rejection episodes, follow-up examination, nutrition and outcome. Mean peri-operative blood transfusions were 204 mL/kg, 188 mL/kg of plasma and 36 mL/kg of platelets; mean operative time was 5 h. Primary abdominal wound closure was possible in nine patients. Median initial intensive care unit stay was 18 days. Reasons for an initial stay of more than 18 days were retransplantation (1), gastrointestinal bleeding (2), paralytic ileus and atelectasis (2), septic shock (2), diaphragmatic paralysis, renal impairment and acute respiratory distress syndrome (2). Mean requirement for artificial ventilation was 168 h. Mean use of dobutamine, prostaglandin E(1) and dopamine was 3.3, 7.5 and 8.8 days, respectively. Parenteral nutrition was started at a mean of 48 h and oral food intake was started at a mean of 72 h. The most frequent complications were infection, atelectasis, gastrointestinal bleeding, acute renal failure and hepatic artery thrombosis. Four children required six re-explorations and two received retransplantation. Mean overall survival rate was 82% and graft survival was 72%. Weight alone (under 7 kg) should not be considered as a contraindication for LT. The survival rate of children post-LT is excellent regardless of graft type.

In 2002 it was discovered that a lightning discharge can rise out of the top of tropical thunderstorms and branch out spectacularly to the base of the ionosphere at 90 km altitude. Several dozens of such gigantic jets have been recorded or photographed since, but eluded capture by high-speed video cameras. Here we report on 4 gigantic jets recorded in Colombia at a temporal resolution of 200 µs to 1 ms. During the rising stage, one or more luminous steps are revealed at 32-40 km, before a continuous final jump of negative streamers to the ionosphere, starting in a bidirectional (bipolar) fashion. The subsequent trailing jet extends upward from the jump onset, with a current density well below that of lightning leaders. Magnetic field signals tracking the charge transfer and optical Geostationary Lightning Mapper data are now matched unambiguously to the precisely timed final jump process in a gigantic jet.

ABSTRACT3D mapping system like the LMA -Lightning Mapping Array -are a leap forward in lightning observation. LMA measurements has lead to an improvement on the analysis of the fine structure of lightning, allowing to characterize the duration and maximum extension of the cloud fraction of a lightning flash. During several years of operation, the first LMA deployed in Europe has been providing a large amount of data which now allows a statistical approach to compute the full duration and horizontal extension of the in-cloud phase of a lightning flash. The "Ebro Lightning Mapping Array" (ELMA) is used in the present study. Summer and winter lighting were analyzed for seasonal periods (Dec-Feb and Jun-Aug). A simple method based on an ellipse fitting technique (EFT) has been used to characterize the spatio-temporal dimensions from a set of about 29,000 lightning flashes including both summer and winter events. Results show an average lightning flash duration of 440 ms (450 ms in winter) and a horizontal maximum length of 15.0 km (18.4 km in winter). The uncertainties for summer lightning lengths were about ± 1.2 km and ± 0.7 km for the mean and median values respectively. In case of winter lightning, the level of uncertainty reaches up to 1 km and 0.7 km of mean and median value. The results of the successful correlation of CG discharges with the EFT method, represent 6.9% and 35.5% of the total LMA flashes detected in summer and winter respectively. Additionally, the median value of lightning lengths calculated through this correlative method was approximately 17 km for both seasons. On the other hand, the highest median ratios of lightning length to CG discharges in both summer and winter were reported for positive CG discharges.

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In the near future, much of the Earth's lightning activity will be continuously monitored from space by lightning imagers placed in geostationary orbit. These new satellite-based instruments open a new era of weather monitoring and research into the role of thunderstorm processes in the dynamics of the atmosphere and in climate change. The Geostationary Lightning Mapper (GLM) on the first of the Geostationary Operational Environmental Satellite GOES-R Series (GOES-16 at 75.2 W) is the first lightning detector in geostationary orbit (Goodman et al., 2013; Rudlosky et al., 2019a, 2019b). GLM is based on its predecessors, the Optical Transient Detector (OTD) and Lightning Imaging Sensor (LIS) Boccippio et al., 2002, Christian et al., 1989). In China, the Lightning Mapping Imager (LMI) on the Feng-Yun4 is detecting lightning in Asia (Yang et al., 2017) and in the near future, Europe and Africa will be continuously monitored by the Lightning Imager (LI) on the Meteosat Third Generation satellites (MTG) (Stuhlmann et al., 2005). All of these systems, new to the geostationary orbit, use optical imagers at the narrow spectral line at the 777.4 nm infrared emission of atomic oxygen that is associated with hot lightning channels (e.g., Soler et al., 2020). The Atmosphere-Space Interactions Monitor (ASIM) on the International Space Station (ISS) consists of a suite of optical instruments and X-ray and gamma-ray detectors for investigating lightning, Transient Luminous Events (TLEs) and Terrestrial Gamma-ray Flashes (TGFs) (e.g., Chanrion et al., 2019; Neubert et al., 2019). ASIM is equipped with three photometers at 180-230 nm, 337.0 and 777.4 nm spectral bands plus two one-megapixel cameras at 337.0 and 777.4 nm. The objective of the 337.0 nm (blue) and 777.4 nm