Geophysical Research Letters

El Niňo related meridional oscillation of global lightning activity



The self-consistent behavior of the frequency level and semiannual intensity variations of the first three Schumann resonance (SR) modes observed at Nagycenk (47.6°N, 16.7°E) indicates a southward shift in the global position of the lightning activity in warm El Niňo years and a northward shift in cool La Niňa years, especially in the longitudinal range where Africa dominates the activity. The third SR mode has a crucial role in recognizing these meridional shifts due to the special angular distance of Nagycenk with respect to the African thunderstorm region. The diurnal zonal redistribution of the worldwide thunderstorm activity manifests in characteristic daily frequency patterns. The preserved daily frequency patterns with changing frequency levels in the same months of the different years imply that the meridional shifts of the lightning activity exist in worldwide sense on the ENSO time scale. The estimated shifts are about 4–8° in latitude.