Symmetric and antisymmetric convection signals in the Madden-Julian oscillation. Part I

Basic modes in infrared brightness temperature

Wen Wen Tung, Dimitrios Giannakis, Andrew J. Majda

Research output: Contribution to journalArticle

Abstract

This work studies the significance of north-south asymmetry in convection associated with the 20-90-day Madden-Julian oscillation (MJO) propagating across the equatorial Indo-Pacific warm pool region. Satellite infrared brightness temperature data in the tropical belt for the period 1983-2006 were decomposed into components symmetric and antisymmetric about the equator. Using a recent nonlinear objective method called nonlinear Laplacian spectral analysis, modes of variability were extracted representing symmetric and antisymmetric features ofMJOconvection signals, along with a plethora of other modes of tropical convective variability spanning diurnal to interannual time scales. The space-time reconstruction of these modes during the 1992/93 Tropical Ocean Global Atmosphere Coupled Ocean-Atmosphere Response Experiment (TOGA COARE) period is described in detail. In particular, the boreal winter MJOemerges as a single pair of modes in both symmetric and antisymmetric convection signals. Both signals originate in the Indian Ocean around 60°E. They coexist for all significant MJO events with a varying degree of relative importance, which is affected by ENSO. The symmetric signals tend to be suppressed when crossing the Maritime Continent, while the antisymmetric signals are not as inhibited. Their differences in peak phase and propagation speed suggest fundamental differences in the underlying mechanisms. The multiscale interactions between the diurnal, MJO, and ENSO modes of convection were studied. It was found that the symmetric component of MJO convection appears out of phase with the symmetric component of the diurnal cycle, while the antisymmetric component of MJO convection is in phase with the antisymmetric diurnal cycle. The former relationship likely breaks down during strong El Niño events, and both relationships likely break down during prolonged La Niña events.

Original languageEnglish (US)
Pages (from-to)3302-3326
Number of pages25
JournalJournal of the Atmospheric Sciences
Volume71
Issue number9
DOIs
StatePublished - 2014

Fingerprint

Madden-Julian oscillation
brightness temperature
convection
El Nino-Southern Oscillation
TOGA-COARE
warm pool
spectral analysis
asymmetry
timescale
winter

Keywords

  • Convection
  • ENSO
  • Madden-Julian oscillation
  • Pattern detection
  • Principal components analysis
  • Tropical variability

ASJC Scopus subject areas

  • Atmospheric Science

Cite this

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title = "Symmetric and antisymmetric convection signals in the Madden-Julian oscillation. Part I: Basic modes in infrared brightness temperature",
abstract = "This work studies the significance of north-south asymmetry in convection associated with the 20-90-day Madden-Julian oscillation (MJO) propagating across the equatorial Indo-Pacific warm pool region. Satellite infrared brightness temperature data in the tropical belt for the period 1983-2006 were decomposed into components symmetric and antisymmetric about the equator. Using a recent nonlinear objective method called nonlinear Laplacian spectral analysis, modes of variability were extracted representing symmetric and antisymmetric features ofMJOconvection signals, along with a plethora of other modes of tropical convective variability spanning diurnal to interannual time scales. The space-time reconstruction of these modes during the 1992/93 Tropical Ocean Global Atmosphere Coupled Ocean-Atmosphere Response Experiment (TOGA COARE) period is described in detail. In particular, the boreal winter MJOemerges as a single pair of modes in both symmetric and antisymmetric convection signals. Both signals originate in the Indian Ocean around 60°E. They coexist for all significant MJO events with a varying degree of relative importance, which is affected by ENSO. The symmetric signals tend to be suppressed when crossing the Maritime Continent, while the antisymmetric signals are not as inhibited. Their differences in peak phase and propagation speed suggest fundamental differences in the underlying mechanisms. The multiscale interactions between the diurnal, MJO, and ENSO modes of convection were studied. It was found that the symmetric component of MJO convection appears out of phase with the symmetric component of the diurnal cycle, while the antisymmetric component of MJO convection is in phase with the antisymmetric diurnal cycle. The former relationship likely breaks down during strong El Ni{\~n}o events, and both relationships likely break down during prolonged La Ni{\~n}a events.",
keywords = "Convection, ENSO, Madden-Julian oscillation, Pattern detection, Principal components analysis, Tropical variability",
author = "Tung, {Wen Wen} and Dimitrios Giannakis and Majda, {Andrew J.}",
year = "2014",
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TY - JOUR

T1 - Symmetric and antisymmetric convection signals in the Madden-Julian oscillation. Part I

T2 - Basic modes in infrared brightness temperature

AU - Tung, Wen Wen

AU - Giannakis, Dimitrios

AU - Majda, Andrew J.

PY - 2014

Y1 - 2014

N2 - This work studies the significance of north-south asymmetry in convection associated with the 20-90-day Madden-Julian oscillation (MJO) propagating across the equatorial Indo-Pacific warm pool region. Satellite infrared brightness temperature data in the tropical belt for the period 1983-2006 were decomposed into components symmetric and antisymmetric about the equator. Using a recent nonlinear objective method called nonlinear Laplacian spectral analysis, modes of variability were extracted representing symmetric and antisymmetric features ofMJOconvection signals, along with a plethora of other modes of tropical convective variability spanning diurnal to interannual time scales. The space-time reconstruction of these modes during the 1992/93 Tropical Ocean Global Atmosphere Coupled Ocean-Atmosphere Response Experiment (TOGA COARE) period is described in detail. In particular, the boreal winter MJOemerges as a single pair of modes in both symmetric and antisymmetric convection signals. Both signals originate in the Indian Ocean around 60°E. They coexist for all significant MJO events with a varying degree of relative importance, which is affected by ENSO. The symmetric signals tend to be suppressed when crossing the Maritime Continent, while the antisymmetric signals are not as inhibited. Their differences in peak phase and propagation speed suggest fundamental differences in the underlying mechanisms. The multiscale interactions between the diurnal, MJO, and ENSO modes of convection were studied. It was found that the symmetric component of MJO convection appears out of phase with the symmetric component of the diurnal cycle, while the antisymmetric component of MJO convection is in phase with the antisymmetric diurnal cycle. The former relationship likely breaks down during strong El Niño events, and both relationships likely break down during prolonged La Niña events.

AB - This work studies the significance of north-south asymmetry in convection associated with the 20-90-day Madden-Julian oscillation (MJO) propagating across the equatorial Indo-Pacific warm pool region. Satellite infrared brightness temperature data in the tropical belt for the period 1983-2006 were decomposed into components symmetric and antisymmetric about the equator. Using a recent nonlinear objective method called nonlinear Laplacian spectral analysis, modes of variability were extracted representing symmetric and antisymmetric features ofMJOconvection signals, along with a plethora of other modes of tropical convective variability spanning diurnal to interannual time scales. The space-time reconstruction of these modes during the 1992/93 Tropical Ocean Global Atmosphere Coupled Ocean-Atmosphere Response Experiment (TOGA COARE) period is described in detail. In particular, the boreal winter MJOemerges as a single pair of modes in both symmetric and antisymmetric convection signals. Both signals originate in the Indian Ocean around 60°E. They coexist for all significant MJO events with a varying degree of relative importance, which is affected by ENSO. The symmetric signals tend to be suppressed when crossing the Maritime Continent, while the antisymmetric signals are not as inhibited. Their differences in peak phase and propagation speed suggest fundamental differences in the underlying mechanisms. The multiscale interactions between the diurnal, MJO, and ENSO modes of convection were studied. It was found that the symmetric component of MJO convection appears out of phase with the symmetric component of the diurnal cycle, while the antisymmetric component of MJO convection is in phase with the antisymmetric diurnal cycle. The former relationship likely breaks down during strong El Niño events, and both relationships likely break down during prolonged La Niña events.

KW - Convection

KW - ENSO

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KW - Pattern detection

KW - Principal components analysis

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JF - Journals of the Atmospheric Sciences

SN - 0022-4928

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