HAO Colloquium - Scott England, Virginia Tech

Impacts of atmospheric tides on the composition of the upper atmosphere and density of the ionosphere

Atmospheric waves are evident throughout Earth’s upper atmosphere. A particularly notable type of these waves are atmospheric tides, which can create global-scale modulations of the upper atmosphere. Features corresponding to these atmospheric tides are also found in observations of the ionosphere – the charged particle counterpart to our upper atmosphere. It is widely thought that the primary mechanism responsible for imprinting this signature of the atmospheric waves on the ionosphere involves the wind-driven dynamo, near the base of the upper atmosphere. However, both theory and modeling suggest that other mechanisms such as changes in the neutral atmosphere’s density and composition should also play a part. Providing observational confirmation of this has proved difficult, owing to the observations of the composition being influenced by changes in the ionosphere, that may be misinterpreted. Analogous observations at Mars have also revealed similar atmospheric waves, and corresponding ionospheric features. However, at Mars it is believed that modification of the atmospheric density and composition is the primary cause of the ionospheric signatures, and electrodynamics plays no role. The new ICON spacecraft, with coordinated observations of Earth’s upper atmosphere and ionosphere offers an opportunity to see if the same mechanism that is so dominant at Mars can also play a role at Earth.

Date and time: 
Wednesday, November 11, 2020 - 2:00pm to 3:00pm