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Vertical Wave Coupling in the Low-Latitude Ionosphere-Thermosphere as revealed by Concurrent ICON and COSMIC-2 Observations
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  • Federico Gasperini,
  • Geoffrey Crowley,
  • Thomas Immel,
  • Brian Harding
Federico Gasperini
Orion Space Solutions, Orion Space Solutions

Corresponding Author:[email protected]

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Geoffrey Crowley
Orion Space Solutions, Orion Space Solutions
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Thomas Immel
University of California, Berkeley, University of California, Berkeley
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Brian Harding
University of California, Berkeley, University of California, Berkeley
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Abstract

It is now well established that waves generated in the lower atmosphere can propagate upward and significantly impact the dynamics and mean state of the ionosphere-thermosphere (IT, 100-600 km) system. Given the geometry of magnetic field lines near the equator, a significant fraction of this IT coupling occurs at low latitudes and is driven by global-scale waves of tropical tropospheric origin, such as the diurnal eastward-propagating tide with zonal wavenumber 3 (DE3) and the ultra-fast Kelvin wave (UFKW). Despite recent progress, lack of coincident global observations has thus far precluded full characterization of the sources of day-today variability of these waves, including nonlinear interactions, and impacts on the low-latitude IT. In this work, in-situ ion densities from Ionospheric Connection Explorer (ICON) and Constellation Observing System for Meteorology, Ionosphere and Climate 2 (COSMIC-2) Ion Velocity Meter (IVM) along with remotely-sensed zonal winds from ICON Michelson Interferometer for Global High-resolution Thermospheric Imaging (MIGHTI) are used to reveal a rich spectrum of waves coupling the lower (∼90-105 km) and middle (∼200-270 km) thermosphere with the upper F-region (∼540 and ∼590 km) ionosphere. Spectral analyses for a 40-day period of similar local time demonstrate prominent IT coupling via DE3, a 3-day UFKW, and the two ∼1.43-day and ∼0.77-day secondary waves from their nonlinear interactions. While all these waves are found to dominate the F-region spectra, only the UFKW and the 1.43-day secondary wave can propagate to ∼270 km suggesting E-region wind dynamo processes as major contributors to their observed ionospheric signatures.