Variations in number of lightning discharge radio pulses by observations in Yakutsk

The main natural source of very low-frequency radiation (LFR: 3-30 kHz) is a lightning discharge which generates radio pulses, namely atmospherics. The atmospherics were registered in the period from 2001-2015 30 km away from Yakutsk (62N; 129,72 E) in the context of industrial noise-free environment. A receive path corresponds to a band of ground lightning discharge’s energy concentration: 0,3-10 kHz. The threshold level of a field, received by a frame antenna ~2 mV/m, which provides an opportunity to register radio pulses at night propagation conditions is up to ~6 000 km. The specific period of a daily variation: minimum 3-7 UT (minimum thunderstorm activity, maximum radio signal attenuation); the summer maximum 8-12 UT (influence of local thunderstorms, maximum signal attenuation); the winter and summer maximum 15-19 UT (minimum attenuation in radio signal propagation). The variation of maximums 17 h (UT) - 230 % (summer to winter) and 9 h (UT) - 2 600 % (local thunderstorms in summer). The 11-year variation is a half-wave with the maximum of 1 year earlier than the minimum of solar activity. The flow of atmospherics is in an antiphase with the solar activity and in a phase with the variation of cosmic rays. From the maximum to the minimum of the solar activity (2001-2007) the change of radio pulse flow 3-7 UT has comprised 59 and 13 times; 15-19 UT comprised 38 and 5 times; 8-12 UT comprised 34 and 8 in winter and summer, respectively. According to our observations, by registering radio signals of a radio navigation system RSDN-20, in the radio path Novosibirsk - Yakutsk the change of attenuation from the minimum to the maximum of the solar activity is 120 %. Taking into account the propagation, the ratio between the number of atmospherics, accepted in the minimum of the solar activity (2009) and the maximum (2013) for summer months is 159 %.