A link between variability of the semidiurnal tide and planetary waves in the opposite hemisphere

Abstract

Horizontal wind observations over four years from the meteor radar at Esrange (68°N, 21°E) are analyzed to determine the variability of the semidiurnal tide. Simultaneous global observations of temperature and geopotential from the SABER satellite instrument are used to construct time series of planetary wave amplitudes and geostrophic mean zonal wind. During Northern Hemisphere summer and fall, the temporal variability of the semidiurnal tide at Esrange is found to be well correlated with the amplitude of planetary wavenumber 1 in the stratosphere in high southern latitudes (i.e. in the opposite hemisphere). The correlations indicate that a significant part of the tidal variation at Esrange is due to dynamical interactions in the Southern Hemisphere. A corresponding robust correlation pattern for the Esrange tides is not apparent at other times of the multiple years analyzed. Copyright 2007 by the American Geophysical Union.