Abstract. Atmospheric tides are important for the vertical coupling in the atmosphere from the stratosphere down to the troposphere and up to the ionosphere. They are gravity waves with well-known periods that are integer fractions of a day and can be observed in the temperature or wind field in the atmosphere. Current lidar and satellite techniques measure atmospheric tides only in the temperature field and continuous measurements of the tides in the wind field of the stratosphere and lower mesosphere are not available. In this study, we present measurements of the diurnal tide in the wind field in the stratosphere and lower mesosphere by ground based microwave wind radiometry for two different campaigns in tropical and polar regions. Further, we compare our measurements to MERRA-2 reanalysis data. In the three-monthly mean, we find a good overall correspondence between measurements and reanalysis with the most important features of the diurnal tides represented in both data sets. When looking at shorter timescales, we find an intermittency of the diurnal tide that is not represented in the MERRA-2 reanalysis data. We conclude, that continuous ground based observations of tides in the middle atmospheric wind field are feasible, even on short timescales of 7 to 13 days, and thus provide additional insight to middle atmospheric dynamics that is complementary to temperature observations and reanalysis data.
The Seasonal Variation of the Propagating Diurnal Tide in the Mesosphere and Lower Thermosphere. Part I: The Role of Gravity Waves and Planetary Waves
