Analysis of 11-years dynamics in spatial distribution of lightning density in north asia

In this study, we analyzed 11-year time series of lightning strokes number over two large areas with increased lightning density (more than 10 times compared with the values in the surrounding area). The so-called “eastern” region is 40–55º N, 110–140º E, and the “western” region is 47–62º N, 60–90º E. The discrete decomposition of the series (of daily resolution) using the Meyer wavelet function to fifth level (eastern) and forth level (western) showed a shift in the maximum of seasonal variation in the regions from the beginning of June to beginning of August from year to year with a period of about 3 years. The periodicity in the seasonal variations of lightning number obtained by the Fourier spectra appeared in the western region more clearly: 4, 7, 14 days. The spatial distribution of lightning density in North Asia can be described as a belt around 50º N with a more than 5 degrees latitude shift to the south in the east with significant peaks in density especially in two regions. The analytical expression is suggested in the form of a latitudinal Gaussian function varying with longitude summarized with a linear function as the background decline to the north of the general lightning activity level. Thus, estimates of the variability of the analytical expression parameters defined the latitudinal-longitudinal distribution of the lightning density on a ten-year scale were obtained.