Abstract
The instrumental continuous monitoring of lightning activity in Yakutia has been carried by the lightning direction finder since the 2000s. Devices for detection of sferic (very low frequency radio pulses emitted by lightning discharges) in Yakutia were supplemented in 2009 with relatively short-range (effective detection radius up to 480 km) single-point Stormtracker and LD-250 direction finders from Boltek Corporation (Welland, ON, Canada). The Stormtracker gives a slightly overestimated ratio of CG strokes due to the amplitude threshold of a single-point direction finder, but the device has not changed over the years, which allows for the consideration of the annual dynamics of parameters. In 2009, a sensor in Yakutsk was included in the World Wide Lightning Location Network (WWLLN). The seasonal and diurnal variations of the total lightning stroke number in the central part and the entire area of Yakutia were obtained (up to 1200 km in radius and limited by latitude–longitude boundaries of 105–150° E, 55–75° N). The longest thunderstorm seasons are often observed in the southern part of Yakutia. There was a slight increase in the duration of the thunderstorm season until 2015 in the central part of Yakutia. The interannual variations in the total number of lightning strokes showed periodic fluctuations (with a period of about three years) over the whole area of Yakutia. The periods of high lightning activity shifted within a season from year to year, as revealed by the monthly stroke number variation. Thus, the maximum lightning rate occurred at the beginning of summer, in the middle or at the beginning of August, and had a period of about three years. Every summer, there were 2–3 periods of high lightning activity, resulting from the moving average with a two-week window (according to the longest duration of cyclones). If the periods of high lightning activity shifted toward the beginning of summer, a decrease in the number of days between seasonal peaks was observed. If the maximum shifted to the beginning of August, the number of days between peaks increased. The ratio of cloud-to-ground (CG) lightning strokes and the ratio of negative CG strokes was slightly decreasing by 2015 in the central part of Yakutia.
Highlights
The northeastern parts of Asia, including Yakutia, are low-population regions and are sparsely covered by instrumental observation of lightning activity
The greatest lightning stroke numbers over the strokes according to the World Wide Lightning Location Network (WWLLN) data corrected by the network’s relative detection efficiency) over whole Yakutia region were in the summers of 2017 and 2019
The study presents the results of instrumental observation of lightning activity in the Yakutia region for the period of 2009–2019
Summary
The northeastern parts of Asia, including Yakutia, are low-population regions and are sparsely covered by instrumental observation of lightning activity. Based on the method of sferic detection, Mullayarov and Kozlov developed a lightning direction finder and started long-term digital recording in 1999 [3,4,5]. They found the average seasonal variation of sferic numbers and areas with high lightning density in Yakutia within a radius of 1200 km around Yakutsk.
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