Source for the traveling planetary waves in the polar winter mesosphere and lower thermosphere: vertical coupling versus in-situ instability.

Xian Lu, Clemson University, Physics and Astronomy, Clemson, SC, United States, Cao Chen, CIRES, Boulder, CO, United States, Xinzhao Chu, University of Colorado at Boulder, CIRES & Aerospace, Boulder, CO, United States, Vu Nguyen, Spire Global, Inc., Boulder, United States and Anne K Smith, National Center for Atmospheric Research, Boulder, CO, United States