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Multi-modal excitation to model the Quasi-Biennial Oscillation (2011.03389v1)
Published 6 Nov 2020 in physics.flu-dyn and physics.ao-ph
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.