Planetary wave-tide nonlinear interactions increase the variety of MLT waves in summer 2019

Mesospheric winds collected by multiple meteor radars at mid-latitudes in the northern hemispheric are combined to investigate wave activities in June—October 2019. Dual-station approaches are developed and implemented to diagnose zonal wavenumber $m$ of spectral peaks. In September—October, diagnosed are quasi‐10‐ and 6‐day planetary waves (Q10DW and Q6DW, $m=$1), solar semi-diurnal tides with $m=$1, 2, 3 (SW1, SW2, and SW3), lunar semi-diurnal tide, and the upper and lower sidebands (USB and LSB, $m=$ 1 and 3) of Q10DW‐SW2 nonlinear interactions. During June— September, diagnosed are Rossby-gravity modes ($m=$3 and 4 at periods $T=$ 2.1d and 1.7d), and their USBs and LSBs generated from interactions with diurnal, semi-diurnal, ter-diurnal, and quatra-diurnal migrating tides. These results demonstrate that the planetary wave-tide nonlinear interactions significantly increase the variety of waves in the mesosphere and lower thermosphere region (MLT).