Investigation of Small-Scale Intra-Cloud Discharges in a Thundercloud According to the VHF Interferometer Data

The work is devoted to the processing and analysis of data of an interferometer that records radio emission in the ultrashort wavelength range. The work is presented in four parts: Introduction, Problem Statement, Experiment and Results. The aim of the paper was to learn how to process real data, to implement noise filtering methods and signals decomposing algorithms. Also, the task was to implement a program for determining the position of micro discharges in a thundercloud. Considered many successful experiments and computer simulation results. The available and promising methods for conducting experiments and observations are considered. Various mechanisms for the artificial initiation of lightning are discussed. The paper implements methods for decomposing a non-stationary and non-linear signal, alternative to Fourier spectral analysis: Empirical Mode Decomposition algorithm and its improvements CEEMDAN (Complete Ensemble Empirical Mode Decomposition with Adaptive Noise). During testing of the CEEMDAN method, it was found that energy and frequency of decomposed white noise are linearly coupled, which allows filtering noise modes during signal decomposition. The algorithm for determining the position of discharges in the celestial sphere was developed and tested with the data obtained from scientific bases in Tarusa and Armenia. As a result of a detailed analysis, a pattern was found in the data: the number of discharges decreases with an increase in their spatial scale. Since the behavior of the slope of this histogram over time is of great interest, there is a need for measurements with an increased time window. Over time, small-scale discharges are expected to become smaller, while large-scale discharges formed by the fusion mechanism of streamers will occur more frequently.