[1] The present paper is focused on the global spatial (altitude and latitude) structure and seasonal and interannual variability of the migrating diurnal tide derived from the Sounding of the Atmosphere using Broadband Emission Radiometry/ThermosphereIonosphere-Mesosphere-Energetics and Dynamics (SABER/TIMED) temperature measurements for 6 full years (January 2002 to December 2007. The tidal results are obtained by a new analysis method where the tides (migrating and nonmigrating) and the planetary waves (zonally traveling and stationary) are simultaneously extracted from the satellite data. It has been found that above 70 km height the SABER migrating diurnal tide reflects mainly the distinctive features of the first symmetric propagating (1,1) mode, while below this height it reflects the features of the first symmetric trapped (1,À2) mode. The trapped component amplifies near 50 km, and its phase is close to $1600 LT. The seasonal behavior of the diurnal tide over the equator is dominated by semiannual variation with a primary maximum in February-March (18 K, average amplitude for 6 years) and a secondary maximum in August-September (15 K). The tidal amplitude grows rapidly in the mesosphere/lower thermosphere; however, it undergoes some decay near $90 km, defining ubiquitous double-peaked vertical structure. A very rapid reduction in amplitude is detected at heights near 115 km; however, above this level the diurnal tide amplifies again. The vertical wavelength of the propagating diurnal tide is $20 km over the equator; at middle latitudes it is not very different from that over the equator, but its magnitude depends on the season. In the winter it is longer than that in summer. The interannual variability of the diurnal tide indicates a clear correlation with the stratospheric quasi-biennial oscillation.Citation: Mukhtarov, P., D. Pancheva, and B. Andonov (2009), Global structure and seasonal and interannual variability of the migrating diurnal tide seen in the SABER/TIMED temperatures between 20 and 120 km,
The vertical coupling of the stratosphere‐mesosphere system through quasi‐stationary and traveling planetary waves during the major sudden stratospheric warming (SSW) in the Arctic winter of 2003/2004 has been studied using three types of data. The UK Met Office (UKMO) assimilated data set was used to examine the features of the global‐scale planetary disturbances present in the winter stratosphere of the Northern Hemisphere. Sounding the Atmosphere using Broadband Emission Radiometry (SABER) satellite measurements were used as well for extracting the stationary planetary waves in the zonal and meridional winds of the stratosphere and mesosphere. Radar measurements at eight stations, four of them situated at high latitudes (63–69°N) and the other four at midlatitudes (52–55°N) were used to determine planetary waves in the mesosphere‐lower thermosphere (MLT). The basic results show that prior to the SSW, the stratosphere‐mesosphere system was dominated by an upward and westward propagating ∼16‐day wave detected simultaneously in the UKMO and MLT zonal and meridional wind data. After the onset of the SSW, longer‐period (∼22–24 days) oscillations were observed in the zonal and meridional MLT winds. These likely include the upward propagation of stationary planetary waves from below and in situ generation of disturbances by the dissipation and breaking of gravity waves filtered by stratospheric winds.
Abstract. The coupling of the dynamical regimes in the high-and low-latitude stratosphere and mesosphere during the major SSW in the Arctic winter of 2003/2004 has been studied. The UKMO zonal wind data were used to explore the latitudinal coupling in the stratosphere, while the coupling in the mesosphere was investigated by neutral wind measurements from eleven radars situated at high, highmiddle and tropical latitudes. It was found that the inverse relationship between the variability of the zonal mean flows at high-and low-latitude stratosphere related to the SSW is produced by global-scale zonally symmetric waves. Their origin and other main features have been investigated in detail. Similar latitudinal dynamical coupling has been found for the mesosphere as well. Indirect evidence for the presence of zonally symmetric waves in the mesosphere has been found.
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