Signature of Planetary Waves in the Thermosphere/Ionosphere System

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The investigation of the response of the thermosphere/ionosphere system (TIS) on neutral atmosphere planetary waves (PW) is the aim of this work. PW do not propagate above 130km. Despite this, oscillations with PW periods and wavenumbers (planetary wave-type oscillations, PWTO) are registered in the TIS. Thus, indirect processes must be responsible for transporting the PW energy upwards. Different possibilities are suggested in the literature, e.g. PW modulation of gravity waves (GW) and tides and modulation of the ionospheric electrojet. In this project, the GW modulation will be considered. The work described in this proposal consists of three parts. The first one will contribute with analyses on ionospheric electron densities related to PWTO and travelling ionospheric disturbances (TID). The second part uses measurements from the mesosphere-lower thermosphere (TIMED/SABER temperatures and meteor radar winds) to detect PW and GW activity, aiming to prove a possible interaction of GW and PW. Numerical modelling will be performed to support the results. In the third scope of work the results of both forgoing parts are compared to reveal the affect of GW on the ionosphere and verify the possible transport of PW energy by secondary waves.