Spatiotemporal patterns of lower-band whistler mode waves in the magnetosphere of Earth

Abstract

Abstract Electromagnetic emissions of lower-band chorus and exohiss waves are known to interact with electrons in the Earth’s outer radiation belt. Understanding statistical properties of these natural emissions is essential for modeling space weather hazards and protecting satellite infrastructure. Despite extensive previous studies, their spatiotemporal characteristics remain incompletely understood. Here, we analyze a large data set of spacecraft measurements, showing that distributions of wave amplitudes exhibit a wide log-normal core with an irregular heavy tail, changing with geomagnetic activity and location. The distribution of time intervals between wave detections follows a power law, suggestive of temporal bunching. Around local noon, we nearly always detect waves up to high latitudes, while intense waves occur for less than a few percent of the time, predominantly in the postmidnight equatorial region. Our findings indicate that the burstiness of whistler-mode waves may not be fully captured by long-term averages, which are commonly used in radiation belt modeling.