Traveling Atmospheric Disturbances in the Midlatitude Thermosphere: Coordinated Ground- and Space-Based Observations

Abstract:

Traveling atmospheric disturbances (TADs) are one of the most effective mechanisms for plasma transport in the mid latitude ionosphere, and its effects are important for a better understanding of the midlatitude electrodynamics. They can be generated by different sources mostly due to geomagnetic effects (Joule heating, sub-auroral polarization streams among others) or to effects coming from below (sudden stratospheric warming, etc) from which only the longer wavelength waves reach the mid-latitude region. Their signatures in the thermosphere and ionosphere have been extensively studied mostly using ionospheric sounding techniques and through density observations. We present the analysis of a large TAD event occurring over North America on January 2, 2020 which showed oscillations in the thermospheric winds with magnitudes larger than 100 m/s in the east-west direction. Signatures were observed by a Fabry-Perot Interferometer (FPI) at the Urbana Atmospheric Observatory in Illinois (UAO; 40.17°N, 88.16°W) showing these oscillations and an apparent east to west propagation direction. We compare these ground-based observations with corresponding neutral wind measurements from the Michelson Interferometer for Global High-resolution Thermospheric Imaging (MIGHTI) instrument on NASA’s Ionospheric CONnection (ICON) Explorer satellite. We also present an analysis of the possible sources for such an event.