Speaker
Description
Understanding the origins of ultra-low frequency (ULF) geomagnetic pulsations is central to space weather research due to their critical role in magnetosphere-ionosphere coupling and radiation belt dynamics. We present a comprehensive multi-spacecraft study using ARTEMIS, Cluster, GOES, and THEMIS data to investigate how step-like and quasi-periodic variations in solar wind dynamic pressure excite geomagnetic pulsations in the 0.5 to 15 mHz frequency range. Focusing on intervals of slow solar wind and low geomagnetic activity to isolate external pressure-driven waves, we detect common periodicities in magnetospheric electromagnetic oscillations and upstream solar wind drivers. Causal relationships are probed through detailed spectral and polarization analyses employing continuous wavelet transforms, cross-wavelet spectra, and wavelet coherence techniques. Our observations confirm that dynamic pressure variations in the upstream solar wind generate Pc4-5 waves that propagate into the dayside magnetosphere predominantly through field line resonance. These ULF waves contribute significantly to radial diffusion processes by transporting radiation belt electrons across magnetic field lines, thereby influencing electron acceleration, loss, and overall radiation belt morphology. This study not only advances understanding of solar wind-magnetosphere interactions but also provides key constraints for modeling wave-particle interactions and radial diffusion-driven dynamics critical for space weather prediction.
