First comparison of travelling atmospheric disturbances observed in the
middle thermosphere by GOLD to travelling ionospheric disturbances seen
in ground-based total electron content observations
Abstract
Travelling ionospheric disturbances (TIDs) and their neutral
counterparts known as travelling atmospheric disturbances (TADs) are
believed to play a central role in redistributing energy and momentum in
the upper atmosphere and communicating inputs to other locations in the
fluid. While these two phenomena are believed to be connected, they may
not have a one-to-one correspondence as the geomagnetic field influences
the TID but has no direct impact on the TAD. The relative amplitudes of
the perturbations seen in the ionosphere and atmosphere have been
observed but rarely together. This study reports results from a
three-day campaign to observe TIDs and TADs simultaneously over a broad
latitudinal region over the eastern United States using a combination of
GOLD and a distributed network of ground based Global Navigation
Satellite System (GNSS) receivers. These results demonstrate that GOLD
and the ground-based total electron content (TEC) observations can see
the atmospheric and ionospheric portions of a large-scale travelling
disturbance. The phase difference in the perturbations to the GOLD
airglow brightness, O/N2 and thermospheric disk
temperature are consistent with an atmospheric gravity wave moving
through this region. The ionospheric signatures move at the same rate as
those in the atmosphere, but their amplitudes do not have a simple
correspondence to the amplitude of the signal seen in the atmosphere.
This campaign demonstrates a proof-of-concept that this combination of
observations is able to provide information on TIDs and TADs, including
quantifying their impact on the temperature and chemical composition of
the upper atmosphere.