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Eastern Pacific ITCZ Dipole and ENSO Diversity

Eastern Pacific ITCZ Dipole and ENSO Diversity AbstractThe eastern tropical Pacific features strong climatic asymmetry across the equator, with the intertropical convergence zone (ITCZ) displaced north of the equator most of time. In February–April (FMA), the seasonal warming in the Southern Hemisphere and cooling in the Northern Hemisphere weaken the climatic asymmetry, and a double ITCZ appears with a zonal rainband on either side of the equator. Results from an analysis of precipitation variability reveal that the relative strength between the northern and southern ITCZ varies from one year to another and this meridional seesaw results from ocean–atmosphere coupling. Surprisingly this meridional seesaw is triggered by an El Niño–Southern Oscillation (ENSO) of moderate amplitudes. Although ENSO is originally symmetric about the equator, the asymmetry in the mean climate in the preceding season introduces asymmetric perturbations, which are then preferentially amplified by coupled ocean–atmosphere feedback in FMA when deep convection is sensitive to small changes in cross-equatorial gradient of sea surface temperature. This study shows that moderate ENSO follows a distinct decay trajectory in FMA and southeasterly cross-equatorial wind anomalies cause moderate El Niño to dissipate rapidly as southeasterly cross-equatorial wind anomalies intensify ocean upwelling south of the equator. In contrast, extreme El Niño remains strong through FMA as enhanced deep convection causes westerly wind anomalies to intrude and suppress ocean upwelling in the eastern equatorial Pacific. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Journal of Climate American Meteorological Society

Eastern Pacific ITCZ Dipole and ENSO Diversity

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Publisher
American Meteorological Society
Copyright
Copyright © American Meteorological Society
ISSN
1520-0442
eISSN
1520-0442
DOI
10.1175/JCLI-D-17-0905.1
Publisher site
See Article on Publisher Site

Abstract

AbstractThe eastern tropical Pacific features strong climatic asymmetry across the equator, with the intertropical convergence zone (ITCZ) displaced north of the equator most of time. In February–April (FMA), the seasonal warming in the Southern Hemisphere and cooling in the Northern Hemisphere weaken the climatic asymmetry, and a double ITCZ appears with a zonal rainband on either side of the equator. Results from an analysis of precipitation variability reveal that the relative strength between the northern and southern ITCZ varies from one year to another and this meridional seesaw results from ocean–atmosphere coupling. Surprisingly this meridional seesaw is triggered by an El Niño–Southern Oscillation (ENSO) of moderate amplitudes. Although ENSO is originally symmetric about the equator, the asymmetry in the mean climate in the preceding season introduces asymmetric perturbations, which are then preferentially amplified by coupled ocean–atmosphere feedback in FMA when deep convection is sensitive to small changes in cross-equatorial gradient of sea surface temperature. This study shows that moderate ENSO follows a distinct decay trajectory in FMA and southeasterly cross-equatorial wind anomalies cause moderate El Niño to dissipate rapidly as southeasterly cross-equatorial wind anomalies intensify ocean upwelling south of the equator. In contrast, extreme El Niño remains strong through FMA as enhanced deep convection causes westerly wind anomalies to intrude and suppress ocean upwelling in the eastern equatorial Pacific.

Journal

Journal of Climate – American Meteorological Society

Published: Jun 29, 2018

References

  • El Niño Modoki and its possible teleconnection
    Ashok, K.; Behera, S. K.; Rao, S. A.; Weng, H.; Yamagata, T.
  • Atmospheric teleconnections from the equatorial Pacific
    Bjerknes, J.
  • Increasing frequency of extreme El Niño events due to greenhouse warming
    Cai, W. J.
  • Understanding ENSO diversity
    Capotondi, A.
  • Climate fluctuations of tropical coupled systems—The role of ocean dynamics
    Chang, P.
  • A coupled ocean–atmosphere instability of relevance to the seasonal cycle
    Chang, P.; Philander, S. G.
  • Analagous meridional modes of atmosphere–ocean variability in the tropical Pacific and tropical Atlantic
    Chiang, J. C. H.; Vimont, D. J.
  • El Niño impacts on seasonal U.S. atmospheric circulation, temperature, and precipitation anomalies: The OLR-event perspective
    Chiodi, A. M.; Harrison, D. E.
  • Observational and model evidence for positive low-level cloud feedback
    Clement, A. C.; Burgman, R.; Norris, J. R.
  • The ERA-Interim reanalysis: Configuration and performance of the data assimilation system
    Dee, D. P.
  • Large-scale atmospheric circulation features of warm and cold episodes in the tropical Pacific
    Deser, C.; Wallace, J. M.
  • Sea surface temperature variability: Patterns and mechanisms
    Deser, C.; Alexander, M. A.; Xie, S.-P.; Phillips, A. S.
  • Role of air–sea interaction in the long persistence of El Niño–induced north Indian Ocean warming
    Du, Y.; Xie, S.-P.; Huang, G.; Hu, K.
  • ICOADS release 3.0: A major update to the historical marine climate record
    Freeman, E.
  • Extended reconstructed sea surface temperature version 4 (ERSST.v4): Part I: Upgrades and intercomparisons
    Huang, B.
  • Changes in the sea surface temperature threshold for tropical convection
    Johnson, N. C.; Xie, S.-P.
  • The impact of eastern equatorial Pacific convection on the diversity of boreal winter El Niño teleconnection patterns
    Johnson, N. C.; Kosaka, Y.
  • Contrasting eastern-Pacific and central-Pacific types of ENSO
    Kao, H. Y.; Yu, J. Y.
  • Photographic cloud climatology from ESSA III and V computer produced mosaics
    Kornfield, J.; Hasler, A. F.; Hanson, K. J.; Suomi, V. E.
  • Two types of El Niño events: Cold tongue El Niño and warm pool El Niño
    Kug, J. S.; Jin, F. F.; An, S. I.
  • TropFlux: Air-sea fluxes for the global tropical oceans—Description and evaluation
    Kumar, B. P.; Vialard, J.; Lengaigne, M.; Murty, V. S. N.; McPhaden, M. J.
  • Increasing intensity of El Niño in the central-equatorial Pacific
    Lee, T.; McPhaden, M. J.
  • Contrasting the termination of moderate and extreme El Niño events in coupled general circulation models
    Lengaigne, M.; Vecchi, G. A.
  • Intermember variability of the summer northwest Pacific subtropical anticyclone in the ensemble forecast
    Ma, J.; Xie, S.-P.; Xu, H.
  • Contributions of the North Pacific Meridional Mode to ensemble spread of ENSO prediction
    Ma, J.; Xie, S.-P.; Xu, H.
  • The role of the mean state in meridional mode structure and growth
    Martinez-Villalobos, C.; Vimont, D. J.
  • The effect of the South Pacific convergence zone on the termination of El Niño events and the meridional asymmetry of ENSO
    McGregor, S.; Timmermann, A.; Schneider, N.; Stuecker, M. F.; England, M. H.
  • Genesis and evolution of the 1997-98 El Niño
    McPhaden, M. J.
  • The annual cycle in equatorial convection and sea surface temperature
    Mitchell, T. P.; Wallace, J. M.
  • Over 5,000 years of ensemble future climate simulations by 60-km global and 20-km regional atmospheric models
    Mizuta, R.
  • A role of zonal gradient of SST between the Indian Ocean and the western Pacific in localized convection around the Philippines
    Ohba, M.; Ueda, H.
  • Interhemispheric coherence of tropical climate variability: Effect of the climatological ITCZ
    Okajima, H.; Xie, S.-P.; Numaguti, A.
  • Asymmetry in the duration of El Niño and La Niña
    Okumura, Y. M.; Deser, C.
  • The oceanic response to cross-equatorial winds (with application to coastal upwelling in low latitudes)
    Philander, S. G. H.; Pacanowski, R. C.
  • ERA-20C: An atmospheric reanalysis of the twentieth century
    Poli, P.
  • An improved in situ and satellite SST analysis for climate
    Reynolds, R. W.; Rayner, N. A.; Smith, T. M.; Stokes, D. C.; Wang, W. Q.
  • Tropical ocean contributions to California’s surprisingly dry El Niño of 2015/16
    Siler, N.; Kosaka, Y.; Xie, S.-P.; Li, X.
  • Strong and moderate nonlinear El Niño regimes
    Takahashi, K.; Dewitte, B.
  • The very strong coastal El Niño in 1925 in the far-eastern Pacific
    Takahashi, K.; Martínez, A. G.
  • ENSO regimes: Reinterpreting the canonical and Modoki El Niño
    Takahashi, K.; Montecinos, A.; Goubanova, K.; Dewitte, B.
  • Abrupt termination of the 1997-98 El Niño in response to a Madden–Julian oscillation
    Takayabu, Y. N.; Iguchi, T.; Kachi, M.; Shibata, A.; Kanzawa, H.
  • Regional patterns of tropical Indo-Pacific climate change: Evidence of the Walker circulation weakening
    Tokinaga, H.; Xie, S.-P.; Timmermann, A.; McGregor, S.; Ogata, T.; Kubota, H.; Okumura, Y. M.
  • The termination of the 1997–98 El Niño. Part I: Mechanisms of oceanic change
    Vecchi, G. A.; Harrison, D. E.
  • El Niño—The dynamic response of the equatorial Pacific Ocean to atmospheric forcing
    Wyrtki, K.
  • Global precipitation: A 17-year monthly analysis based on gauge observations, satellite estimates, and numerical model outputs
    Xie, P.; Arkin, P. A.
  • On the genesis of the equatorial annual cycle
    Xie, S.-P.
  • Westward propagation of latitudinal asymmetry in a coupled ocean–atmosphere model
    Xie, S.-P.
  • A coupled ocean-atmosphere model of relevance to the ITCZ in the eastern Pacific
    Xie, S.-P.; Philander, S. G. H.
  • Decadal shift in El Niño influences on Indo–western Pacific and East Asian climate in the 1970s
    Xie, S.-P.; Du, Y.; Huang, G.; Zheng, X.-T.; Tokinaga, H.; Hu, K.; Liu, Q.
  • Anomalous tropical cyclone activity in the western North Pacific in August 2014
    Yang, L.; Wang, X.; Huang, K.; Wang, D.
  • Interannual signature in daily ITCZ states in the east Pacific in boreal spring
    Yang, W.; Magnusdottir, G.
  • Explaining the year-to-year variability of the eastern Pacific intertropical convergence zone in the boreal spring
    Yu, H. Y.; Zhang, M. H.
  • Intermodel uncertainty in ENSO amplitude change tied to Pacific Ocean warming pattern
    Zheng, X. T.; Xie, S.-P.; Lv, L. H.; Zhou, Z. Q.