A dynamical ocean feedback mechanism for the Madden-Julian Oscillation

Webber, Benjamin G. M. ORCID: https://orcid.org/0000-0002-8812-5929, Matthews, Adrian J. ORCID: https://orcid.org/0000-0003-0492-1168 and Heywood, Karen J. ORCID: https://orcid.org/0000-0001-9859-0026 (2010) A dynamical ocean feedback mechanism for the Madden-Julian Oscillation. Quarterly Journal of the Royal Meteorological Society, 136. pp. 740-754. ISSN 1477-870X

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Composite analysis is applied to study the dynamical ocean response to Madden-Julian (MJ) events, measured by anomalies in sea surface height from the merged TOPEX/Poseidon-European Remote Sensing satellite altimetry dataset. In each of the tropical ocean basins, significant equatorial waves are forced, which are shown to modulate the sea surface temperature (SST) by 0.2-0.3 degC in the absence of strong surface heat fluxes. In the Indian Ocean there is a clear dynamical response which may play a significant role in generating later MJ events. Surface westerly winds, associated with the active phase of the Madden-Julian Oscillation (MJO), force an eastward-propagating oceanic downwelling equatorial Kelvin wave, which, on reaching the eastern boundary at Sumatra, forces reflected downwelling equatorial Rossby waves and coastal Kelvin waves. The coastal Kelvin waves propagate southwards towards northern Australia and northwards into the Bay of Bengal, and will be important for local physical, chemical and biological processes. The equatorial Rossby waves propagate westward across the Indian Ocean, arriving in the western Indian Ocean approximately 80-100 days after the initial Kelvin wave was generated. The arrival of these waves generates positive SST anomalies which leads to convection and may trigger the next-but-one MJ event, or amplify the low-frequency tail of the MJO. This constitutes a coupled feedback mechanism from the ocean dynamics onto the MJO, somewhat similar to the delayed oscillator mechanism for the El Nino Southern Oscillation.

Item Type: Article
Faculty \ School: Faculty of Science > School of Environmental Sciences
University of East Anglia Research Groups/Centres > Theme - ClimateUEA
UEA Research Groups: Faculty of Science > Research Groups > Climatic Research Unit
Faculty of Science > Research Groups > Centre for Ocean and Atmospheric Sciences
Faculty of Science > Research Groups > Marine and Atmospheric Sciences (former - to 2017)
Faculty of Science > Research Groups > Meteorology, Oceanography and Climate Dynamics (former - to 2017)
Faculty of Science > Research Groups > Volcanoes@UEA (former - to 2018)
Faculty of Science > Research Groups > Climate, Ocean and Atmospheric Sciences (former - to 2017)
Depositing User: Vishal Gautam
Date Deposited: 10 Mar 2011 12:00
Last Modified: 15 Jun 2023 13:30
URI: https://ueaeprints.uea.ac.uk/id/eprint/20918
DOI: 10.1002/qj.604

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