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- Title
An Analysis of Gravity Wave Spectral Characteristics in Moist Baroclinic Jet-Front Systems.
- Authors
Wei, Junhong; Zhang, Fuqing; Richter, Jadwiga H.
- Abstract
This study investigates gravity wave spectral characteristics based on high-resolution mesoscale simulations of idealized moist baroclinic jet-front systems with varying degrees of convective instability, with the intent of improving nonorographic gravity wave parameterizations. In all experiments, there is a clear dominance of negative vertical flux of zonal momentum. The westward momentum flux is distributed around the estimated ground-based baroclinic wave phase velocity along the zonal direction, while strong moist runs indicate a dipole structure pattern with stronger westward momentum flux centers at slower phase velocity and weaker eastward momentum flux centers at faster phase velocity. The spectral properties of short-scale wave components (50-200 km) generally differ from those of medium-scale ones (200-600 km). Compared to the medium-scale wave components, the momentum flux phase speed spectra for the short-scale ones appear to be more sensitive to the increasing initial moisture content. The spectral behavior in horizontal wavenumber space or phase velocity space is highly anisotropic, with a noticeable preference along the jet direction, except for the short-scale components in strong moist runs. It is confirmed that the dry gravity wave source (i.e., upper jet and/or surface front) generates a relatively narrow and less symmetrical power spectrum (dominated by negative momentum flux) centered around lower phase velocity and horizontal wavenumber, whereas the moist gravity wave source (i.e., moist convection) generates a broader and more symmetrical power spectrum, with a broader range of phase speeds and horizontal wavenumbers. This study also shows that the properties of gravity wave momentum flux depend on the location relative to the baroclinic jet.
- Subjects
GRAVITY waves; ATMOSPHERIC turbulence; GENERAL circulation model; RADIATIVE forcing; CLIMATE sensitivity; MATHEMATICAL models
- Publication
Journal of the Atmospheric Sciences, 2016, Vol 73, Issue 8, p3133
- ISSN
0022-4928
- Publication type
Article
- DOI
10.1175/JAS-D-15-0316.1