Papers with references to CRD 2022
- January 2022
Relativistic runaway electron avalanches (RREA) accelerated by thunderstorm large-scale electric fields are one of the sources of atmospheric gamma radiation. In strong electric fields, RREAs can multiply by the relativistic feedback. Infinite relativistic feedback makes avalanches self-sustainable and hypothetically can cause a terrestrial gamma-ray flash (TGF). This paper introduces a kinetic approach to study the relativistic feedback caused by positrons since positron feedback dominates for the directly observed electric field strengths. With this approach, the criterion for infinite positron feedback within thunderstorms is derived. Discovered criterion allows obtaining the thunderstorm electric field parameters required for infinite positron feedback for any altitude. The possibility of derived thunderstorm conditions is discussed.
I. Kolmašová,S. Soula,O. Santolík,T. Farges,O. Bousquet,G. Diendorfer,R. Lán,L. Uhlíř
05 February 2022
We combine electromagnetic measurements with meteorological and lightning detection data to explain an observation of unusually strong preliminary breakdown (PB) produced by a thunderstorm system that developed along the Mediterranean Coast of Southern France in the early hours of 19 June 2013. This multi-cellular storm was composed of several parallel convective lines in the NW-SE direction. Our analysis focuses on ten sequences of energetic electromagnetic PB pulses recorded by two receivers located at different distances from this thunderstorm. The peak currents, which generated these strong PB pulses, reached -36 kA. The initial polarity of all observed energetic PB pulses confirmed the movement of the negative charge downward, as in case of PB pulses preceding negative cloud-to-ground discharges. The locations of PB pulses appeared in areas with none or very weak lightning activity. Most PB pulses were initiated in small, short-living, rapidly moving convective storm cells characterized by low reflectivity values (generally < 40 dBZ), weak vertical development, and low flash density. Our findings indicate that the observed thunderstorm might posses temporary strong negatively charged pockets located above a strong positive charge region at low-level. Such charge arrangement, likely explains our observation of unusually strong PB pulses and the absence of RS pulses in electromagnetic recordings....
Liubov Ben-Nun, Professor Emeritus
B. N. Publication House. Israel. 2022
McGovern & al. (1) mentioned that severe weather, including tornadoes, thunderstorms, wind, and hail annually cause significant loss of life and property. The Authors are developing spatiotemporal machine learning techniques that will enable meteorologists to improve the prediction of these events by improving their understanding of the fundamental causes of the phenomena and by building skillful empirical predictive models. In this paper, significant enhancements of the Spatiotemporal Relational Probability Trees enable autonomous discovery of spatiotemporal relationships as well as learning with arbitrary shapes. The evaluation was focused on two real-world case studies using the technique: predicting tornadoes in Oklahoma and predicting aircraft turbulence in the United States. It was also discussed how to evaluate success for a machine learning algorithm in the severe weather domain, which will enable new methods such as ours to transfer from research to operations, provide a set of lessons learned for embedded machine learning applications, and discuss how to field our technique (1)...