A tropical stochastic skeleton model for the MJO, El Niño, and dynamic walker circulation

A simplified GCM

Sulian Thual, Andrew Majda, Nan Chen

Research output: Contribution to journalArticle

Abstract

A simple dynamical stochastic model for the tropical ocean atmosphere is proposed that captures qualitatively major intraseasonal to interannual processes altogether including El Niño-Southern Oscillation (ENSO), the Madden-Julian oscillation (MJO), the associated wind bursts, and the background dynamic Walker circulation. Such a model serves as a prototype "skeleton" for general circulation models (GCMs) that solve similar dynamical interactions across several spatiotemporal scales but usually show common and systematic biases in representing tropical variability as a whole. The most salient features of ENSO, the wind bursts, and the MJO are captured altogether including their overall structure, evolution, and fundamental interactions in addition to their intermittency, diversity, and energy distribution across scales. Importantly, the intraseasonal wind bursts and the MJO are here solved dynamically, which provides their upscale contribution to the interannual flow as well as their modulation in return in a more explicit way. This includes a realistic onset of El Niño events with increased wind bursts and MJO activity starting in the Indian Ocean to the western Pacific and expanding eastward toward the central Pacific, as well as significant interannual modulation of the characteristics of intraseasonal variability. A hierarchy of cruder model versions is also analyzed in order to highlight fundamental concepts related to the treatment of multiple time scales, main convective nonlinearities, and the associated stochastic convective parameterizations. The model developed here also should be useful to diagnose, analyze, and help eliminate the strong tropical biases that exist in current operational models.

Original languageEnglish (US)
Pages (from-to)9261-9282
Number of pages22
JournalJournal of Climate
Volume31
Issue number22
DOIs
StatePublished - Nov 1 2018

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Walker circulation
Madden-Julian oscillation
skeleton
general circulation model
Southern Oscillation
nonlinearity
parameterization
timescale
atmosphere
ocean
energy

Keywords

  • Atmosphere-ocean interaction
  • ENSO
  • Madden-Julian oscillation
  • Statistical techniques
  • Stochastic models

ASJC Scopus subject areas

  • Atmospheric Science

Cite this

A tropical stochastic skeleton model for the MJO, El Niño, and dynamic walker circulation : A simplified GCM. / Thual, Sulian; Majda, Andrew; Chen, Nan.

In: Journal of Climate, Vol. 31, No. 22, 01.11.2018, p. 9261-9282.

Research output: Contribution to journalArticle

Thual, Sulian ; Majda, Andrew ; Chen, Nan. / A tropical stochastic skeleton model for the MJO, El Niño, and dynamic walker circulation : A simplified GCM. In: Journal of Climate. 2018 ; Vol. 31, No. 22. pp. 9261-9282.
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