PLANETARY WAVE SIGNATURES IN F-REGION ELECTRON DENSITIES

PLANETARY WAVE SIGNATURES IN F-REGION ELECTRON DENSITIES
Sona Baiju, Jens Oberheide

Planetary waves (PW) originating from the stratosphere and mesosphere induce significant oscillations in the F-region ionosphere at periods of 2–20 days. It appears intriguing because PWs cannot propagate directly into the ionosphere, raising questions about the mechanisms responsible for their periodicities in this region. An important mechanism is the non-linear interaction between tides and planetary waves below 100 km and coupling to the ionosphere through the dynamo generation of electric fields. However, the variability of electron density (Ne) at PW periods associated with zonally symmetric oscillation remains an open question as these oscillations cannot be due to E-region dynamo action. Despite their potential impact, PW signatures in the F-region ionosphere remain largely unexplored from an observational perspective, with most studies relying on model simulations. This work aims to test these model predictions and to investigate the potential mechanisms using satellite data. The least-square fitting method is applied to electron density profiles from COSMIC-2 (Constellation Observing System for Meteorology, Ionosphere, and Climate-2) and temperature profiles from the SABER (Sounding of the Atmosphere using Broadband Emission Radiometry) instrument aboard NASA’s TIMED (Thermosphere, Ionosphere, Mesosphere, Energetics, and Dynamics) satellite to estimate the amplitudes of the PW oscillations in the F-region and E-region. We also present a wavelet filtering technique that minimizes solar and geomagnetic effects in the detected F-region PWs, to more clearly identify oscillations that are purely due to planetary waves.