A local-to-large scale view of Maritime Continent rainfall: Control by ENSO, MJO and equatorial waves

Peatman, Simon C., Schwendike, Juliane, Birch, Cathryn E., Marsham, John H., Matthews, Adrian J. ORCID: https://orcid.org/0000-0003-0492-1168 and Yang, Gui-Ying (2021) A local-to-large scale view of Maritime Continent rainfall: Control by ENSO, MJO and equatorial waves. Journal of Climate, 34 (22). pp. 8933-8953. ISSN 0894-8755

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The canonical view of the Maritime Continent (MC) diurnal cycle is deep convection occurring over land during the afternoon and evening, tending to propagate offshore overnight. However, there is considerable day-to-day variability in the convection, and the mechanism of the offshore propagation is not well understood. We test the hypothesis that large-scale drivers such as ENSO, the MJO, and equatorial waves, through their modification of the local circulation, can modify the direction or strength of the propagation, or prevent the deep convection from triggering in the first place. Taking a local-to-large scale approach, we use in situ observations, satellite data, and reanalyses for five MC coastal regions, and show that the occurrence of the diurnal convection and its offshore propagation is closely tied to coastal wind regimes that we define using the k-means cluster algorithm. Strong prevailing onshore winds are associated with a suppressed diurnal cycle of precipitation, while prevailing offshore winds are associated with an active diurnal cycle, offshore propagation of convection, and a greater risk of extreme rainfall. ENSO, the MJO, equatorial Rossby waves, and westward mixed Rossby–gravity waves have varying levels of control over which coastal wind regime occurs, and therefore on precipitation, depending on the MC coastline in question. The large-scale drivers associated with dry and wet regimes are summarized for each location as a reference for forecasters.

Item Type: Article
Additional Information: Data availability statement: The “pre-YMC” and “YMC” field campaign data are archived by the Japan Agency for Marine-Earth Science and Technology (JASMTEC) at http://www.jamstec.go.jp/ymc/ymc_data.html.
Uncontrolled Keywords: clustering,diurnal effects,enso,intraseasonal variability,madden-julian oscillation,maritime continent,precipitation,rawinsonde observations,rossby waves,sea breezes,atmospheric science ,/dk/atira/pure/subjectarea/asjc/1900/1902
Faculty \ School: Faculty of Science > School of Environmental Sciences
Faculty of Science > School of Natural Sciences
University of East Anglia Research Groups/Centres > Theme - ClimateUEA
UEA Research Groups: Faculty of Science > Research Groups > Centre for Ocean and Atmospheric Sciences
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Depositing User: LivePure Connector
Date Deposited: 17 Aug 2021 00:18
Last Modified: 20 Mar 2023 08:35
URI: https://ueaeprints.uea.ac.uk/id/eprint/81121
DOI: 10.1175/JCLI-D-21-0263.1


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