Travelling Ionospheric Disturbances Detected by the Scintillation
Observations and Response of The Ionosphere to Electrodynamics (SORTIE)
CubeSat at 420 km Altitude
Abstract
The Scintillation Observations and Response of The Ionosphere to
Electrodynamics (SORTIE) mission is a 6U CubeSat that has been making
ionospheric measurements at 420 km altitude since February 19, 2020. The
SORTIE sensor suite includes an Ion Velocity Meter (IVM), which is used
in the present study to detect and characterize Traveling Ionospheric
Disturbances (TIDs). On July 11, 2020 the SORTIE orbit passed over
near-concentric TIDs that were seen in the Total Electron Content (TEC)
data from ground-based Global Positioning System receivers distributed
across the COntiguous United States (CONUS). The TID wave
characteristics estimated from the IVM data agree well with those
determined from the ground-based TEC data. The wave periods derived from
the SORTIE data are shorter than the TID periods in the TEC data but are
anticipated and explained in terms of the classical Doppler effect. A
numerical simulation was performed using the Weather Research and
Forecasting (WRF) model that shows excitation of atmospheric gravity
waves (AGWs) from a deep convective storm over Texas preceding TID
observations by SORTIE. We show that these AGWs were observed at
stratospheric heights in close proximity to the convective storm by the
Atmospheric Infrared Sounder onboard the NASA Aqua satellite, and in the
lowermost mesosphere by the Cloud Imaging and Particle Size instrument
onboard the NASA Aeronomy of Ice in the Mesosphere satellite. These
storm-generated AGWs, or the associated higher-order AGWs, are the
likely sources of the TIDs observed in the ground-based TEC and SORTIE
IVM data.