Wavelet Based ULF Pulsation Index for Studying Conjugate ULF Pulsation at High Latitudes and Its Applications to Space Weather

Abstract

A wavelet-based index is described in this study and applied to present geomagnetic Ultra Low Frequency (ULF) pulsations observed in Antarctica and their magnetically conjugate locations in West Greenland. The index is effective for identification of pulsation events in the Pc4-5 frequency range, which is related to the Geomagnetically Induced Currents (GICs) shown by many researchers, and measures important characteristics of ULF pulsations in both the temporal and frequency domains. We discuss how the wavelet indices can be used to monitor geomagnetic pulsations in both hemispheres simultaneously. The wavelet analysis shows valuable information for GIC- related studies, including the spectrum, correlation, and magnitude of the geomagnetic pulsations. The comparison between conjugate locations reveals the similarities and differences of ULF pulsations in both hemispheres. Also, since the Greenland chains are located near the coastal area, while the Antarctic chains are over thousands meters of the ice-sheet on the East Antarctic plateau, inter-hemispheric comparisons of vertical magnetic field perturbations can be used to reveal how sensitive ULF pulsations are to ground conductivity.