Magnetosphere-ionosphere coupling of nighttime MSTIDs from ground and the Arase satellite

Traveling ionospheric disturbances (TIDs) are the propagation of electron density fluctuation in the ionosphere. TIDs are classified as small, medium, and large scale [Hunsucker, 1982]. The generation mechanism of medium-scale TIDs (MSTIDs) in the middle latitudes is based on the theories of ionospheric E-F coupling and Perkins instability. The interhemispheric propagation of nighttime MSTIDs has been confirmed by simultaneous observations of ground airglow imagers in both hemispheres [Otsuka et al., 2004]. Otsuka et al. [2004] suggested that the conjugacy of the electric field along the magnetic field lines played an important role in the MSTID generation. However, the conjugacy of the electric field associated with MSTID had not been reported by magnetospheric satellites. We have firstly reported simultaneous observation of the nighttime MSTIDs with an airglow imager at Gakona (62.39°N, 214.78°E) and the Arase satellite on November 3, 2018 [Kawai et al., 2021]. In this event, the electron density fluctuation and the electric field variation measured by Arase were clearly associated with the MSTIDs. Here, we investigate more simultaneous observations of nighttime MSTIDs with the airglow imagers installed at high latitudes and the Arase satellite for 4 years from April 2017 to April 2021. We analyze electromagnetic fields and plasma densities obtained by Arase and compare them with several MSTID events observed by airglow imagers at 10 stations (Athabasca, Gakona, Kapsukasing, Istok, Zhigansk, Husafell, Magadan, Nyrola, Tromsø, and Paratunka) deployed by the PWING project [Shiokawa et al., 2017]. In most cases, we found no clear correlation between MSTIDs and variations of electromagnetic fields and plasma densities observed by Arase. This result contradicts the fact that most MSTIDs have conjugation at middle latitudes [Otsuka et al., 2004; Shiokawa et al., 2005; Martinis et al., 2017]. We discuss the possibility that there is less propagation of MSTID structures from the ionosphere at high than at middle latitudes.