Global‐scale wave model estimates of nonmigrating tidal effects

Hagan, M. E.; Chang, J. L.; Avery, S. K.

doi:10.1029/97jd01269

Cited by 69 publications

(78 citation statements)

References 43 publications

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“…Temperature oscillations (bottom right) maximize at about 5±8 K near 110 km over the equator. These wind and temperature results are an order of magnitude larger than the migrating diurnal amplitudes associated with the forcing of Williams and Avery (1996) (see also Hagan et al, 1997a).…”

Section: Resultsmentioning

confidence: 99%

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Upper atmosphere tidal oscillations due to latent heat release in the tropical troposphere

et al. 1997

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Abstract. Latent heat release associated with tropical deep convective activity is investigated as a source for migrating (sun-synchronous) diurnal and semidiurnal tidal oscillations in the 80±150-km height region. Satellite-based cloud brightness temperature measurements made between 1988 and 1994 and averaged into 3-h bins are used to determine the annual-and longitude-average local-time distribution of rainfall rate, and hence latent heating, between 40°latitude. Regional average rainfall rates are shown to be in good agreement with climatological values derived from surface rain gauge data. A global linearized wave model is used to estimate the corresponding atmospheric perturbations in the mesosphere/lower thermosphere (80±150 km) resulting from upward-propagating tidal components excited by the latent heating. The annual-average migrating diurnal and semidiurnal components achieve velocity and temperature amplitudes of order 10±20 m s A1 and 5± 10 K, respectively, which represent substantial contributions to the dynamics of the region. The latent heat forcing also shifts the phase (local solar time of maximum) of the semidiurnal surface pressure oscillation from 0912 to 0936 h, much closer to the observed value of 0944 h.

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Section: Resultsmentioning

confidence: 99%

“…Recently, Hagan et al (1997a) investigated tidal signatures associated with tropospheric latent heat release using the GSWM. They employed the heating rates of Williams and Avery (1996) and calculated upper-atmosphere wind perturbations of the order of a few to several m s A1 .…”

Section: Introductionmentioning

confidence: 99%

Upper atmosphere tidal oscillations due to latent heat release in the tropical troposphere

et al. 1997

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“…This model does not consider any nonlinear interactions between tides and planetary waves. The GSWM has been described in detail by Hagan et al (1995Hagan et al ( , 1997Hagan et al ( , 1999 and results from the GSWM00 are available at http://www.hao. ucar.edu/modeling/gswm/gswm.html#ASC24.…”

Section: Tides -Comparison With Gswm00 Predictionsmentioning

confidence: 99%

“…The important details of each model are mentioned in the next section while comparing the models with observations. The climatological monthly means of the diurnal and semidiurnal tidal amplitudes and phases are compared with Global-Scale Wave Model (GSWM-00) predictions (Hagan et al, , 1997.…”

Section: Data Base and Analysismentioning

confidence: 99%

Climatology of northern polar latitude MLT dynamics: mean winds and tides

Kumar

Hocking

2010

Ann. Geophys.

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Abstract. Mean winds and tides in the northern polar Mesosphere and Lower Thermosphere (MLT) have been studied using meteor radars located at Resolute Bay The summer zonal flow is westward at lower heights, eastward at upper heights and the winter zonal flow is eastward at all heights. The winter meridional flow is poleward and sometimes weakly equatorward, while non winter months show equatorward flow, with a strong equatorward jet during mid-summer months. The zonal and meridional winds show strong interannual variation with a dominant annual variation as well as significant latitudinal variation. Year to year variability in both zonal and meridional winds exists, with a possible solar cycle dependence. The diurnal, semidiurnal and terdiurnal tides also show large interannual variability and latitudinal variation. The diurnal amplitudes are dominated by an annual variation. The climatological monthly mean winds are compared with CIRA 86, GEWM and HWM07 and the climatological monthly mean amplitudes and phases of diurnal and semidiurnal tides are compared with GSWM00 predictions. The GEWM shows better agreement with observations than the CIRA 86 and HWM07. The GSWM00 model predictions need to be modified above 90 km. The agreements and disagreements between observations and models are discussed.

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“…These Sun-asynchronous tidal modes are known as nonmigrating modes. Non-migrating tides may also be generated by any other zonally asymmetric diurnally varying heat sources such as planetary boundary layer heat flux (Mckenzie, 1968;Kato et al, 1982;Tsuda and Kato, 1989), solar radiation absorption by zonally varying water vapour (Forbes and Groves, 1987), latent heat release in deep convective clouds and solar radiation absorption by zonally varying water vapour (Williams and Avery, 1996;Hagan et al, 1997). Recently, Lieberman and Leovy (1995) and Ekanayake et al (1997), have done numerical studies of non-migrating tides by incorporating a combination of these different diurnal heat sources.…”

Section: Introductionmentioning

confidence: 99%

Tidal wind oscillations in the tropical lower atmosphere as observed by Indian MST Radar

2001

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Abstract. Diurnal tidal components in horizontal winds measured by MST radar in the troposphere and lower stratosphere over a tropical station Gadanki (13.5 • N, 79.2 • E) are presented for the autumn equinox, winter, vernal equinox and summer seasons. For this purpose radar data obtained over many diurnal cycles from September 1995 to August 1996 are used. The results obtained show that although the seasonal variation of the diurnal tidal amplitudes in zonal and meridional winds is not strong, vertical phase propagation characteristics show significant seasonal variation. An attempt is made to simulate the diurnal tidal amplitudes and phases in the lower atmosphere over Gadanki using classical tidal theory by incorporating diurnal heat sources, namely, solar radiation absorption by water vapour, planetary boundary layer (PBL) heat flux, latent heat release in deep convective clouds and short wave solar radiation absorption by clouds. A comparison of the simulated amplitudes and phases with the observed ones shows that agreement between the two is quite good for the equinox seasons, especially the vertical structure of the phases of the meridional wind components.

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Global‐scale wave model estimates of nonmigrating tidal effects

Cited by 69 publications

References 43 publications

Upper atmosphere tidal oscillations due to latent heat release in the tropical troposphere

Upper atmosphere tidal oscillations due to latent heat release in the tropical troposphere

Climatology of northern polar latitude MLT dynamics: mean winds and tides

Tidal wind oscillations in the tropical lower atmosphere as observed by Indian MST Radar

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