Krakow ELF Group

ELF Electromagnetic Waves and Ionospheric Physics Seminar

                                      April 29, 2026

Qianqian Wang (Institute of Urban Meteorology, Beijing)  

Abstract:

New access to lightning within the AC global circuit is afforded by a high-latitude ELF station (Hornsund; 77°N, 16°E) equipped with perpendicular magnetic coils that provide independent observations of three continental lightning "chimneys" (Asia/Maritime Continent, Africa, America), fortuitously separated by 90° in longitude. Energetic lightning Q-bursts are simultaneously and reliably geo-located by combiningToA and azimuth methods with a separate set of coil pairs at six ELF (HeartMath) stations (California, Canada, Lithuania, Saudi Arabia, South Africa and New Zealand). These dual Schumann resonance methods have been used to identify systematic lightning behavior in each of three chimneys, involving a peak response in "background" activity near 4 pm local time (roughly 10 UT, 15 UT and 21 UT in each of three chimneys), with consistent lag behavior of positive Q-burst relative to negative ones (0.3h, 0.5h, 2.83h for each of three chimneys). This lead-lag behavior is attributed to the prevalence of negative Q-bursts in the early/mature convection portions of the chimney diurnal cycle, and the prevalence of positive Q-bursts in the later decay phase with stratiform conditions. Consistent time lag of positive Q-bursts and time lead of negative Q-bursts relative to the respective chimney maxima in background activity are revealed in African and American chimneys; while in the Asian chimney, both negative and positive Q-bursts show a leading behavior. High correlations (0.70, 0.65, 0.51 for each of three chimneys) between positive Q-burst (with CMC>500C?km) counts and background peak intensity indicate that chimneys with stronger ordinary lightning activity are prone to generate more energetic positive Q-bursts later in the chimney cycle. The nature of the convection during different phases of the diurnal cycle has been studied with vertical reflectivity profiles from the NASA GPM precipitation radar taken at the locations of the geo-located Q-bursts. The positive Q-bursts are frequently coincident with radar bright band signatures in these vertical profiles. The daily diurnal variations are dominated by the local 4 pm aftermath but occasionally the signal from strong nocturnal/early morning MCS squall line activity is evident. The demise of both the 4 pm aftermath and the MCS squall lines provides common microphysical conditions (stratiform snowstorm aloft with aggregates feeding the melting layer beneath) for positive Q-burst production.

Contact: Contact_ELFseminar(at)oa.uj.edu.pl