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Annales Geophysicae An interactive open-access journal of the European Geosciences Union
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Volume 24, issue 12
Ann. Geophys., 24, 3241–3256, 2006
https://doi.org/10.5194/angeo-24-3241-2006
© Author(s) 2006. This work is distributed under
the Creative Commons Attribution 3.0 License.
Ann. Geophys., 24, 3241–3256, 2006
https://doi.org/10.5194/angeo-24-3241-2006
© Author(s) 2006. This work is distributed under
the Creative Commons Attribution 3.0 License.

  21 Dec 2006

21 Dec 2006

A numerical study on the impact of nonlinear interactions on the amplitude of the migrating semidiurnal tide

C. M. Huang1,2, S. D. Zhang1,2, and F. Yi1,2 C. M. Huang et al.
  • 1School of Electronic Information, Wuhan University, Wuhan, HUBEI 430079, People's Republic of China
  • 2Laboratory of Geospace Environment and Geodesy, Wuhan University, Wuhan, HUBEI 430079, People's Republic of China

Abstract. To quantitatively study the effects of nonlinear interactions on tide structure, a nonlinear numerical tidal model is developed, and the reliability and convergence of the adopted algorithm and coding are checked by numerical experiments. Under the same conditions as those employed by the GSWM-00 (Global Scale Wave Model 2000), our model provides the nonlinear quasi-steady solution of the migrating semidiurnal tide, which differs from the GSWM-00 result (the linear steady solution) in the MLT region, especially above 100 km. Additionally, their amplitude difference displays a remarkable month-to-month variation, and its significant magnitudes occur during the month with strong semidiurnal tide. A quantitative analysis suggests that the main cause for the amplitude difference is that the initial migrating 12-h tide will interact with the mean flow as well as the nonlinearity-excited 6-h tide, and subsequently yield a new 12-h tidal part. Furthermore, our simulations also show that the mean flow/tidal interaction will significantly alter the background wind and temperature fields. The large magnitudes of the tidal amplitude difference and the background alteration indicate that the nonlinear processes involved in tidal propagations should be comprehensively considered in the description of global atmospheric dynamics in the MLT region. The comparisons among our simulations, the GSWMs and some observations of tides suggest that the nonlinearity-induced tidal structure variation could be a possible mechanism to account for some discrepancies between the GSWMs and the observations.

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