Identification of Two-Step Non-linear Interactions via Zonally Symmetric Waves during Major Sudden Stratospheric Warmings

Abstract

This study delved into atmospheric tides and their dynamics during two major boreal sudden stratospheric warmings (SSWs). Using meteor radar wind data, our investigation unveiled compelling indications of non-linear interactions between the semidiurnal solar tide and the quasi-20-day wave (Q20dw) in the high latitude mesosphere and lower thermosphere (MLT) during SSWs. Additionally, the diagnosis of zonal wavenumbers indicated potential non-linear interaction between the dominant semidiurnal migrating tide (SW2) and the zonally symmetric 20-day wave (20dw0) component, generating secondary waves. The study emphasized the significance of the non-linear interaction between the zonal wavenumber 2 component of the stationary planetary wave (SPW2) and the westward propagating 20-day wave (20dwW2) in the stratosphere, crucial in producing the 20dw0. The meteor radar wind spectra suggested that the excited 20dw0 possibly engages in non-linear interactions with SW2, further generating secondary waves in the MLT. Therefore, this study presents the observational evidence of a two-step non-linear interaction associated with zonally symmetric planetary waves during major SSWs.