The Nonmigrating Semidiurnal Tide With Zonal Wavenumber One Observed Over South Pole and its Relationship With the Stationary Planetary Wave With Zonal Wavenumber One

Early observations of the dynamical features of the mesosphere and lower thermosphere (MLT) over the geographic South Pole revealed the existence of a nonmigrating component of the semidiurnal tide with zonal wavenumber one. Further observational studies have documented the seasonal and interannual behavior of this semidiurnal tide component. These observations have determined that this tide maximizes during the austral summer reaching amplitudes around 20~m/s and disappears during the winter. Moreover, significant amplitude variations have been measured during the summer months. Several hypotheses have been formulated to explain the source of this semidiurnal tide component but recent studies favor the nonlinear interaction of a stationary planetary wave with zonal wavenumber one and the migrating semidiurnal tide as the source of the observed oscillation. Continuous observations of the MLT dynamics over the South Pole have been possible since the installation of a meteor radar at the Amundsen-Scott South Pole station in 2001. The seasonal, interannual, and spatial behavior of the semidiurnal tide with zonal wavenumber one has been and continues to be observed using this meteor radar. In this paper we explore the relationship between our meteor radar measurements of the aforementioned semidiurnal tide component and observations of the stationary planetary wave with zonal wavenumber one obtained from other sources.