Impact of Antarctic Sudden Stratospheric Warming on Low and Mid-Latitude Ionosphere

Abstract:

Sudden stratospheric warming (SSW), a large-scale meteorological disturbance, has been associated with profound anomalies in the Earth atmosphere, from the troposphere all the way to the upper thermosphere and ionosphere. During the last decade, numerous studies showed that Arctic SSWs cause large anomalies in the ionosphere, especially at low latitudes. Limited observational evidence shows that ionospheric changes caused by Arctic SSWs propagate to at least the middle latitudes in the Southern Hemisphere. However, it is not clear if similar ionospheric anomalies are produced by Antarctic SSWs, mostly because Antarctic SSWs occur less often than the Arctic events. In this study we provide an overview of ionospheric anomalies in total electron content observed in September 2019, when an exceptionally strong minor SSW developed over Antarctica. Our results indicate numerous anomalies in the low-latitude ionosphere that act on different temporal scales, including quasi-semidiurnal perturbations, multi-day periodicities, and a general decrease in TEC. Further, we note remarkable longitudinal differences in the observed features, with anomalies varying between locations that are separated by only 30 degrees in longitude. Additionally, we investigate ionospheric anomalies at middle latitudes in the Northern Hemisphere and report significant changes over Europe and the continental U.S. We conclude that Antarctic SSW events can produce even more dynamical changes in the ionosphere than Arctic events. Our results indicate that stratospheric weather can strongly influence the state of the ionosphere not only during the December-February period (winter in the Northern Hemisphere), but also during September (equinox conditions).