Climatology of the diurnal tides from eCMAM30 (1979 to 2010) and its comparison with SABER

Abstract

The extended Canadian Middle Atmosphere Model (eCMAM) was recently run in a nudged mode using reanalysis data from the ground to 1 hPa for the period of January 1979 to June 2010 (hence the name eCMAM30). In this paper, eCMAM30 temperature is used to examine the background mean temperature, the spectrum of the diurnal tides, and the climatology of the migrating diurnal tide Dw1 and three nonmigrating diurnal tides De3, Dw2, and Ds0 in the stratosphere, mesosphere, and lower thermosphere. The model results are then compared to the diurnal tidal climatology derived from Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) observations between 40 to 110 km and 50°S to 50°N from January 2002 to December 2013. The model reproduces the latitudinal background mean temperature gradients well except that the cold mesopause temperature in eCMAM30 is 10 to 20 K colder than SABER. The diurnal tidal spectra and their relative strengths compare very well between eCMAM30 and SABER. The altitude-latitude structures for the four diurnal tidal components (Dw1, De3, Dw2, and Ds0) from the two datasets are also in very good agreement even for structures in the stratosphere with a weaker amplitude. The largest discrepancy between the model and SABER is associated with the seasonal variation of De3. In addition to the Northern Hemisphere (NH) summer maximum, a secondary maximum occurs during NH winter (December-February) in the model but is absent in SABER. The seasonal variations of the other three diurnal tidal components are in good agreement. Interannual time series of Dw1 and De3 from both eCMAM30 and SABER reveal variability with a period of 25 to 26 months, which indicates the modulation of the diurnal tides by the stratospheric quasi-biennial oscillation (QBO).

Temporal variability of tidal and gravity waves during a record long 10-day continuous lidar sounding

“…The appearance of the diurnal wave component in a particular altitude range is frequently related to a trapped mode of the tide, which cannot propagate upward. Such a local maximum of the diurnal tide has also been reported by, for example, Forbes and Wu (2006) and Gan et al (2014). However, results on the temporal variability are generally rare.…”

Statistical analysis of the mesospheric inversion layers over two symmetrical tropical sites: Réunion (20.8° S, 55.5° E) and Mauna Loa (19.5° N, 155.6° W)

“…Nevertheless, we cannot exclude the possibility of tidal aliasing which could underestimate the semi-annual oscillation influence in lidar observations (Gan et al, 2012(Gan et al, , 2014Xu et al, 2007). Leblanc and Hauchecorne (1997) reported that some tidal residuals can affect the altitude and amplitude of some temperature inversions.…”

Observations of thermosphere and ionosphere changes due to the dissipative 6.5-day wave in the lower thermosphere

“…Due to the line of sight of SABER and the yaw maneuver of the TIMED satellite, the latitude coverage of SABER data is from 53 • latitude in one hemisphere to 83 • in the other. In the past decade, SABER temperature has been widely employed for the study of typical thermal structure (Gan et al, 2012) and wave dynamics (Huang et al, 2013;Gan et al, 2014). In the current work, the latest version of temperature data, 2.0, is utilized to identify the 6.5-day wave in temperature.…”