On The Collocation of the Cusp Aurora and the GPS Phase Scintillation: A Statistical Study

Abstract:

The climatology map of the GPS phase scintillation identifies two regions of high scintillation occurrences at high latitudes: around magnetic noon and around magnetic midnight. The scintillation occurrence rate is higher around magnetic noon, while the scintillation level is stronger around magnetic midnight. This study focuses on the dayside scintillation region. In order to resolve the role of the cusp auroral processes in the production of irregularities, we put the GPS phase scintillation in the context of the observed auroral morphology. Results show that the occurrence rate of the GPS phase scintillation is highest inside the auroral cusp, regardless of the scintillation strength and the interplanetary magnetic field (IMF). On average the scintillation occurrence rate in the cusp region is about 5 times as high as in the region immediately poleward of it. The scintillation occurrence rate is higher when the IMF BZ is negative. When partitioning the scintillation data by the IMF BY, the distribution of the scintillation occurrence rate around magnetic noon is similar to that of the poleward moving auroral form (PMAF) statistics: there is a higher occurrence rate at earlier (later) magnetic local time when the IMF BY is positive (negative). This indicates that the irregularities which give rise to scintillations follow the IMF BY controlled East-West motion of the aurora and plasma. Furthermore, the scintillation occurrence rate is higher when IMF BY is positive when the cusp is shifted towards the post-noon sector where it may get easier access to the higher density plasma. This suggests that the combined auroral activities (e.g., PMAF) and the density of the intake solar EUV ionized plasma are crucial for the production of scintillations.