Time Lags Between Ionospheric Scintillation Detection at Northern Auroral Latitudes and Onset of Geomagnetic Storms

Abstract

Ionospheric responses to geomagnetic storms can cause irregular plasma structures and scintillation of Global Navigation Satellite System (GNSS) signals. In this paper, we investigate time lags between the detection of GNSS signal scintillation at northern hemisphere auroral latitudes and the onset of 15 geomagnetic storms that occurred in 2015–2017. The results show that the time lags between the detection of ground‐based GNSS scintillations and the observed sudden change in solar wind parameters are between tens of minutes and 15 hr. This time lag consists of two segments. The first segment is about 30–80 min, which is the lag between observed disturbances in the geomagnetic field and solar wind disturbances detected by orbiting spacecrafts around the L1 point. The second segment is between the observed GNSS signal scintillation and the storm sudden commencement (SSC). This second lag segment varies in the range of about 10–830 min and highly depends on the storm onset time and geomagnetic locations of GNSS signal propagation paths. Longer time lags over 450 min were observed with the signal ionospheric piercing point at 60–70° geomagnetic latitudes (MLAT) on the dayside, while shorter lags of 10∼450 min were observed with the signal IPPs at 68–81° MLAT and on the nightside at the time of SSC. The lag time variations can be explained by ionospheric irregularity production and transport processes associated with a variety of auroral and polar cap phenomena in response to solar wind coupling to the magnetosphere and ionosphere.