Multi-modal excitation to model the Quasi-Biennial Oscillation
arXiv:2011.03389 · doi:10.1103/PhysRevLett.125.234501
Abstract
The Quasi-Biennial Oscillation (QBO) of stratospheric winds is the most striking example of mean-flow generation and reversal by the non-linear interactions of internal waves. Previous studies have used an idealized monochromatic forcing to investigate the QBO. Here we instead force a more realistic continuous wave spectrum. Unexpectedly, spreading the wave energy across a wide frequency range leads to more regular oscillations. We also find that different forcing spectra can yield the same QBO. Multi-modal wave forcing is thus essential for understanding wave/mean-flow interactions in nature.
Main text: 6 pages, 4 figures. Supplemental: 7 pages, 5 figures. To be published in Physical Review Letters