Diurnal nonmigrating tides in the tropical lower thermosphere

Forbes, Jeffrey M.; Hagan, M. E.; Miyahara, S.; Miyoshi, Y.; Zhang, Xiaoli

doi:10.1186/bf03351775

Cited by 42 publications

(60 citation statements)

References 31 publications

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“…Nonmigrating tides are excited for instance by zonal asymmetries (i.e. topography, land-sea differences, longitude dependences in absorbing species) (Forbes et al, 2003) or by nonlinear interactions between the migrating diurnal tide and planetary waves (Hagan and Roble, 2001) or gravity waves (McLandress and Ward, 1994). Another important source of nonmigrating tides and denotative for the observed wave-4 structure is latent heat release in the tropical troposphere .…”

Section: Atmospheric Tidesmentioning

confidence: 99%

Nonmigrating tidal signals in the upper thermospheric zonal wind at equatorial latitudes as observed by CHAMP

2009

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Abstract. The accelerometer onboard CHAMP enables us to derive the thermospheric zonal wind at orbit altitudes (∼400 km). Numerous equatorial overflights (∼45 250) are used to investigate the influence of nonmigrating tides on the thermospheric zonal wind. In a previous study a so called "wave-4" longitudinally signal observed in the satellite frame was identified in the zonal wind residuals during equinox. Using four years of data (2002-2005), we determine the annual variation of this prominent feature which is strongest during the months of July through October and has a smaller second maximum during March/April. Due to the large data set we were able to separate the observed wavenumbers into the tidal components. Thereby, we can identify the eastward propagating diurnal tide with zonal wavenumber s=3 (DE3) as the prime cause for the observed wave-4 pattern in the zonal wind. Analyzing the zonal wind along the geographic and the dip equator revealed that the largest amplitudes of DE3 are found along the dip equator. Besides DE3 we present the full spectrum of nonmigrating tides in the upper thermosphere.

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Section: Atmospheric Tidesmentioning

confidence: 99%

Nonmigrating tidal signals in the upper thermospheric zonal wind at equatorial latitudes as observed by CHAMP

2009

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“…The sun-synchronous or migrating diurnal tide Dw1 a is arguably the largest and most persistent feature of the large-scale wind and temperature fields in the equatorial and low-latitude MLT region ). However, the nonmigrating diurnal tidal amplitudes have been found to be equal to or exceed the migrating diurnal tidal amplitude at some locations and/or time (Lieberman 1991;Forbes et al 2001Forbes et al , 2003aOberheide and Gusev 2002;Du 2008;Ward et al 2010) and cause significant longitudinal variability in the MLT ) and ionospheric region (England 2012). The climatology of both migrating and nonmigrating diurnal tides has been revealed by satellite temperature/wind observations such as the High Resolution Doppler Interferometer (HRDI)/ Wind Imaging Interferometer (WINDII)/Microwave Limb Sounder (MLS) on board the Upper Atmosphere Research Satellite (UARS) (Hays and Wu 1994;McLandress et al 1996;Khattatov et al 1996;Talaat and Lieberman 1999;Ward et al 1999;Forbes et al 2003a, b;Manson et al 2004;Huang and Reber 2004;Forbes and Wu 2006), the TIMED Doppler Interferometer (TIDI)/Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) on board the Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) satellite Zhang et al 2006;Oberheide et al 2006;Wu et al 2008a, b;Pancheva et al 2009;Xu et al 2009b;Sakazaki et al 2012) in the MLT region, and the CHAllenging Minisatellite Payload (CHAMP) radio occultation (RO) (Zeng et al 2008;Pirscher et al 2010;Xie et al 2010) in the upper troposphere and lower stratosphere (UTLS) region.…”

Section: Introductionmentioning

confidence: 99%

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

Gan

Ward

et al. 2014

Earth Planet Space

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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).

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“…More significantly, satellite observations also enabled researchers to separate nonmigrating tides from migrating tides [e.g., Forbes et al, 2003aForbes et al, , 2003bOberheide et al, 2005Oberheide et al, , 2006.…”

Section: Introductionmentioning

confidence: 99%

Global distribution and interannual variations of mesospheric and lower thermospheric neutral wind diurnal tide: 1. Migrating tide

et al. 2008

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[1] Using the TIMED Doppler interferometer (TIDI) mesospheric and lower thermospheric neutral-wind multiyear data set (2002)(2003)(2004)(2005)(2006)(2007) and NCAR TIME General Circulation Models (GCM) 1.2 annual run results (2002)(2003)(2004)(2005) at the TIDI sampling points, we study the migrating diurnal tide's global distribution, interannual, and seasonal variations in connection with the mean zonal wind interannual variations. A strong quasi-biennial oscillation (QBO) effect on the diurnal tide was observed in the TIDI data and reproduced to a lesser degree in the TIME-GCM run. The migrating diurnal tide amplitude is larger during the eastward phase of the stratospheric QBO and weaker during the westward phase. Westward mesospheric equatorial mean zonal winds appeared during the eastward phase of the stratospheric QBO (in 2002, 2004, and 2006). The strongest QBO effect on both the migrating diurnal tide and mean zonal winds was observed during the March equinox. The stronger tides may be related to the weaker gravity wave filtering in the stratosphere during the eastward phase stratospheric QBO. The TIDI data also exhibit large interhemispheric asymmetry. The westward mean zonal winds in the mesosphere appeared to be associated with the enhanced diurnal tide. The TIME-GCM 1.2 diurnal tide amplitudes are in general smaller than those observed by the TIDI instrument. Limited vertical spatial resolution for the TIME-CGM 1.2 is suggested as the cause. Future improvements are expected with a higher spatial resolution in the model.

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Diurnal nonmigrating tides in the tropical lower thermosphere

Cited by 42 publications

References 31 publications

Nonmigrating tidal signals in the upper thermospheric zonal wind at equatorial latitudes as observed by CHAMP

Nonmigrating tidal signals in the upper thermospheric zonal wind at equatorial latitudes as observed by CHAMP

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

Global distribution and interannual variations of mesospheric and lower thermospheric neutral wind diurnal tide: 1. Migrating tide

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