Nonlinear interactions between gravity waves with different wavelengths and diurnal tide

• Published in: Journal of Geophysical Research - Atmospheres Vol. 113; no. D8; pp. D08112 - n/a
• Main Authors: Liu, Xiao, Xu, Jiyao, Liu, Han-Li, Ma, Ruiping
• Format: Journal Article
• Language: English
• Published: Washington, DC American Geophysical Union 27-04-2008; Blackwell Publishing Ltd
• Subjects: Acoustic-gravity waves; Altitude; Amplitudes; Atmospheric Processes; atmospheric tides; Breaking; Computer simulation; Earth sciences; Earth, ocean, space; Exact sciences and technology; Gravity waves; Marine; Mathematical models; Mesospheric dynamics; Middle atmosphere dynamics; Nonlinearity; Theoretical modeling; Tides and planetary waves; Turbulence; Wavelengths; Middle atmosphere dynamics; atmospheric tides; gravity waves; wavelength; altitude; models; shear; penetration; Dispersion relation; digital simulation; Wave breaking; tides; tidal waves; amplitude; Wave propagation; Gravity wave; winds; instability; temperature; Height; direction
• ISSN: 0148-0227; 2169-897X; 2156-2202; 2169-8996
• DOI: 10.1029/2007JD009136

By using a compressible nonlinear two‐dimensional gravity wave model, we simulate the nonlinear interactions between gravity waves (GWs) with three different vertical wavelengths and a meridional component of the diurnal tidal wind and temperature (30°N, September) calculated from GSWM‐00. We also compare the results with the simulation of GWs propagation in a background with zero wind. Consistent with the dispersion relation, the numerical experiments show that tidal wind reduces the vertical wavelengths of the GWs when it is in the same direction as the wave propagation, and thus increases the perturbative shear and the likelihood of instability and wave breaking, especially for waves with shorter vertical wavelengths. The breaking of GWs below the critical level can increase the amplitude of diurnal tidal wind due to the momentum deposition. Because the GW penetration height increases with vertical wavelength, the amplitude of diurnal tidal wave at higher altitudes is more likely to be affected by GWs with large vertical wavelengths. Therefore gravity wave breaking not only accelerates the mean winds, but also increases the amplitudes of the diurnal tide at various altitudes.