Excitation of mixed Rossby-gravity waves by wave-mean flow interactions on the sphere
arxiv(2023)
Abstract
The equatorial mixed Rossby-gravity wave (MRGW) is an important contributor
to tropical variability. Its excitation mechanism capable of explaining the
observed MRGW variance peak at synoptic scales remains elusive. This study
investigates wave-mean flow interactions as a generation process for the MRGWs
using the barotropic version of the global Transient Inertia-Gravity And Rossby
wave dynamics model (TIGAR), which employs Hough harmonics as the basis of
spectral expansion, thereby representing MRGWs as prognostic variables. High
accuracy numerical simulations manifest that interactions between waves
emanating from a tropical heat source and zonal mean jets in the subtropics
generate MRGWs with the variance spectra resembling the one observed in the
tropical troposphere. Quantification of spectral tendencies associated with the
MRGW energy growth underscores the significance of wave-mean flow interactions
in comparison to excitation mechanisms driven by external forcing and wave-wave
interactions. The MRGW growth and amplitude depend on the asymmetry in the
zonal mean flow that may explain not only seasonal variability but also
differences between the troposphere and the middle atmosphere.
MoreTranslated text
AI Read Science
Must-Reading Tree
Example
Generate MRT to find the research sequence of this paper
Chat Paper
Summary is being generated by the instructions you defined