On the evaluation of the phase relation between temperature and wind tides based on ground-based measurements and reanalysis data in the middle atmosphere

Abstract

Abstract. The variability in the middle atmosphere is driven by a variety of waves covering different spatial and temporal scales. We diagnose the variability in the thermal tides due to changes in the background wind by an adaptive spectral filter, which takes the intermittency of tides into account. We apply this diagnostic to temperature observations from daylight-capable lidar at midlatitudes (54∘ N, 12∘ E) as well as to reanalysis data of horizontal winds from Modern-Era Retrospective analysis for Research and Applications, Version 2 (MERRA-2). These reanalysis data provide additional wind information in the altitude range between 30 and 70 km at the location of the lidar as well as on a global scale. Using the global data gives information on the tidal modes seen at one location. A comparison of the temperature and wind information affirms whether there is a fixed phase relation of the tidal waves in the temperature and the wind data. We found that in general the local tidal signatures are dominated by migrating tidal modes, and the signature is weaker in temperatures than in winds. While the meridional wind tide leads the zonal wind tide by 90∘, the phase relation between the temperature and the wind tide is more complex. At certain altitudes the temperature tide follows the zonal wind tide. This knowledge helps in improving the interpretation of the seasonal variation in tides from different observables, especially when only data from single locations are used. The findings provide additional information about the phase stability of tidal waves, and the results clearly show the importance of a measurement acquisition on a routine basis with high temporal and spatial resolution.

Small-scale variability of stratospheric ozone during the sudden stratospheric warming 2018/2019 observed at Ny-Ålesund, Svalbard

“…Lawrence and Manney, 2020;Matthias and Ern, 2018). To characterize the influence of the planetary waves on the variability of the ozone gradients, we calculated amplitude and phase of the stationary planetary waves in the MERRA-2 zonal and meridional wind fields using the wave diagnostics algorithm described in Baumgarten and Stober (2019). We first present the evolution of the stationary planetary waves and discuss the dominant gradient patterns throughout winter 2018/2019 in the context of the planetary wave activity.…”

Small-scale variability of stratospheric ozone during the SSW 2018/2019 observed at Ny-Ålesund, Svalbard

“…ysis data and found that the day-to-day variability was mostly driven by stationary planetary waves 1,2 and 3. To characterize the influence of the planetary waves on the variability of the ozone gradients we calculated amplitude and phase of the stationary planetary waves in the MERRA-2 zonal and meridional wind fields using a wave diagnostics algorithm as described in Baumgarten and Stober (2019). We first present the evolution of the stationary planetary waves and discuss the dominant gradient patterns of October, December and March in the context of the planetary wave activity.…”

Comment on "Migrating and Non-Migrating Tides Observed in the Stratosphere from FORMOSAT-3/COSMIC Temperature Retrievals" by Uma Das et al.

“…Unfortunately, the data is limited to stratospheric altitudes, and therefore a comparison to other data sets can hardly be made as they are often done for the MLT region due to larger tidal amplitudes at these altitudes. However, there are a few studies which investigate the tidal variability also in the stratosphere, which should also be mentioned in the discussion (e.g., Baumgarten et al, 2018, Baumgarten andStober et al, 2019). Both studies show a huge variability of the diurnal tide which origin was not finally determined, but nevertheless, they used also global tidal fields to distinguish between migrating and non-migrating tides.…”