Radio Physics and Radio Astronomy (Sep 2017)
COMPARISON OF AIR TEMPERATURE VARIATIONS ON THE AFRICAN CONTINENT AND THE SCHUMANN RESONANCE INTENSITY BY USING LONG-TERM ANTARCTIC OBSERVATIONS
Abstract
Purpose: Correlation study of long-term seasonal variations of intensity of the global electromagnetic (Schumann) resonance in the Earth-ionosphere cavity and the air temperature for the African center of the global thunderstorm activity. Design/methodology/approach: The correlation analysis of the time series was used. By using the 13-year data (since 2002 till 2015) of monitoring the natural ELF noise at the Ukrainian Antarctic Vernadsky station, the seasonal variations in intensity of the first Schumann resonance mode were derived, driven by the lightning activity in the African thunderstorm center. The average air temperature of the African continent over the same period was estimated from the data collected by the global network of meteorological stations. The area of maximum thunderstorm activity in Africa was approximated by a simple geometric figure. The correction was made for the source distance (the lightning discharges) when estimating the power of the first resonant maximum in the ELF signal. A stable relationship between the air temperature and the thunderstorm activity at the African continent was established as a result of correlation processing of seasonal variations in the air temperature and the field intensity. Findings: A one month lag between the annual maximum resonance intensity was found with regard to the maximum of air temperature relevant to the delay in the formation of thunderstorms during transition from the dry to the rainy seasons in Africa. The cross-correlation coefficient increases from 0.58 (without compensation) to 0.76 (delay compensated) when this delay is accounted for by the relevant shift of temperature variations. Conclusions: The technique developed can be used in finding the connection between the lightning activity of other thunderstorm centers and the corresponding regional temperature conditions. Such an approach might be used in developing the concept of Schumann resonance records as a “global thermometer”.
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