Several of our previous theoretical and observational studies have pointed to the linkage of gravity waves and turbulence in the atmosphere (Koch et al. 2005; Lu et al. 2005a, 2005b). Gravity waves interacting with turbulence are in scales right above the turbulent inertial range, with the wavelength typically on the orders from a few to a few tens of kilometers. However, gravity waves (with pressure perturbation of a few millibars) have shown their strong presence in mesoscales, typically on the order of a few hundred kilometers. One obvious explanation for this scale separation of gravity waves is that different-scale waves are generated by different sources or a source with different intrinsic scales. Apart from this mechanism, there is also a possibility that these waves with different scales are genotypically related, i.e., smaller-scale gravity waves are generated from larger-scale gravity waves via wave-wave interactions. Using spectral analysis and wavelet transformation technique, we analyzed modeled gravity waves from an idealized model simulation. The computed spectral power density from modeled vertical velocity field presents a continuous expansion of wave scales from low wavenumbers to high wavenumbers with time. Wavelet analysis actually localized these waves in physical space. A time series of these wavelet-decomposed waves tends to indicate that smaller-scale waves are spawned by larger-scale waves.
This publication was presented at the following: