Couplings between DE3 tide and longitudinal WN4 structure in the termosphere and ionosphere
DE3, which is excited in the tropical troposphere, has recently attracted a considerable attention because there are growing observational evidences that DE3 is the main source of the longitudinal wave number-4 (WN4) structure in the thermosphere and ionosphere. Two possible coupling mechanisms between DE3 tide and thermospheric and ionospheric WN4 are the upward wave propagation and the electro-dynamical coupling. With a coupled ionosphere-thermosphere-electrodynamics model (GCITEM-IGGCAS) and data from satellite observations,we investigate the couplings between DE3 tide and longitudinal WN4 structure in the thermosphere and ionosphere, and analyze above two possible coupling mechanisms. Data analyze and model simulation shows that the ionospheric and thermospheric longitudinal WN4 structures can be driven by DE3 tide, and both the upward wave propagation and the electro-dynamical coupling play important roles in the couplings between DE3 and longitudinal WN4 structure. Although both the upward wave propagation and the electro-dynamical coupling can drive WN4 structures, the thermospheric WN4 are mainly directly produced by the wave propagation mechanism, and the ionospheric WN4 waves are directly produced by the electro-dynamical coupling.