Normal mode perspective on the 2016 QBO disruption: evidence for a basic state regime transition
| Main Authors: | Breno, Andre Seiji Teruya, Pedro Leite da Silva Dias, Victor Mayta, Victor |
|---|---|
| Format: | Article |
| Terbitan: |
, 2020
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| Online Access: |
https://zenodo.org/record/3711612 |
Daftar Isi:
- A normal mode decomposition of the dynamical structure of the Quasi-biennial Oscillation (QBO) is presented in this article. It is found that the QBO is predominantly described by Rossby modes as well as westward inertio-gravity modes with a low meridional index. We show that the 2016 QBO disruption was accompanied by an extreme amplitude event of an asymmetric zonal Rossby mode with the largest amplitude in 40 years. This zonal mode favors the convergence of eastward momentum in the equatorial region, controlling the perturbations to the QBO. This asymmetric component of the zonal flow is extremely intermittent with a heavy tail distribution. Our statistical analysis indicates a regime transition in this zonal mode in the last decades, favoring stronger perturbations to the QBO.