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Modulation of the Southern Africa precipitation response to the El Nio Southern Oscillation by the subtropical Indian Ocean Dipole

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dc.contributor Sch Geog Archaeol & Environm Studies
dc.contributor University Of Witwatersrand
dc.contributor United States Geological Survey
dc.contributor Free University Of Berlin
dc.contributor Curtin Univ Technol
dc.contributor United States Department Of The Interior
dc.contributor National Oceanic Atmospheric Admin (noaa) - Usa
dc.contributor University Of California Santa Barbara
dc.contributor University Of California System
dc.contributor Free Univ Berlin
dc.contributor Dept Environm & Agr
dc.contributor Inst Geolog Wissensch
dc.contributor Dept Geog
dc.contributor Noaa
dc.contributor Curtin University
dc.contributor Univ Witwatersrand
dc.contributor Us Geol Survey
dc.contributor Earth Resources Observat & Sci Ctr
dc.contributor Australian Inst Marine Sci
dc.contributor Phys Sci Div
dc.contributor Univ Calif Santa Barbara
dc.contributor Earth Syst Res Lab
dc.contributor Australian Institute Of Marine Science
dc.contributor.author HARRISON, LAURA
dc.contributor.author HOELL, ANDREW
dc.contributor.author FUNK, CHRIS
dc.contributor.author ZINKE, JENS
dc.date.accessioned 2017-05-07T20:01:05Z
dc.date.accessioned 2017-05-07T20:01:05Z
dc.date.accessioned 2018-11-01T03:19:00Z
dc.date.available 2017-05-07T20:01:05Z
dc.date.available 2017-05-07T20:01:05Z
dc.date.available 2018-11-01T03:19:00Z
dc.date.issued 2017-04-01
dc.identifier.citation Hoell A, Funk C, Zinke J, Harrison L (2017) Modulation of the Southern Africa precipitation response to the El Nio Southern Oscillation by the subtropical Indian Ocean Dipole. Climate Dynamics 48(7): 2529-2540
dc.identifier.issn 0930-7575
dc.identifier.uri http://epubs.aims.gov.au/11068/1462
dc.description.abstract The climate of Southern Africa, defined as the land area bound by the region 15A degrees S-35A degrees S; 12.5A degrees E-42.5A degrees E, during the December-March rainy season is driven by Indo-Pacific sea surface temperature (SST) anomalies associated with the El Nio Southern Oscillation (ENSO) and the Subtropical Indian Ocean Dipole (SIOD). The observed December-March 1979-2014 Southern Africa precipitation during the four ENSO and SIOD phase combinations suggests that the phase of the SIOD can disrupt or enhance the Southern Africa precipitation response to ENSO. Here, we use a large ensemble of model simulations driven by global SST and ENSO-only SST to test whether the SIOD modifies the relationship between Southern Africa precipitation and ENSO. Since ENSO-based precipitation forecasts are used extensively over Southern Africa, an improved understanding of how other modes of SST variability modulate the regional response to ENSO is important. ENSO, in the absence of the SIOD, forces an equivalent barotropic Rossby wave over Southern Africa that modifies the regional mid-tropospheric vertical motions and precipitation anomalies. El Nio (La Nia) is related with high (low) pressure over Southern Africa that produces anomalous mid-tropospheric descent (ascent) and decreases (increases) in precipitation relative to average. When the SIOD and ENSO are in opposite phases, the SIOD compliments the ENSO-related atmospheric response over Southern Africa by strengthening the regional equivalent barotropic Rossby wave, anomalous mid-tropospheric vertical motions and anomalous precipitation. By contrast, when the SIOD and ENSO are in the same phase, the SIOD disrupts the ENSO-related atmospheric response over Southern Africa by weakening the regional equivalent barotropic Rossby wave, anomalous mid-tropospheric vertical motions and anomalous precipitation.
dc.description.sponsorship The authors thank Dave Allured for completing the ECHAM5.4 simulations and Tao Zhang for completing the GFSv2 simulations. The authors are grateful for support from the Famine Early Warning Systems Network (FEWS NET).
dc.language English
dc.subject Sst Variability
dc.subject Southern Africa
dc.subject Austral Summer
dc.subject Events
dc.subject Impacts
dc.subject Enso
dc.subject El Nino-southern Oscillation
dc.subject Tropical Atlantic
dc.subject Nino
dc.subject Summer Rainfall
dc.subject Precipitation
dc.subject Subtropical Indian Ocean Dipole
dc.subject Climate
dc.subject Meteorology & Atmospheric Sciences
dc.subject Atmosphere Model
dc.title Modulation of the Southern Africa precipitation response to the El Nio Southern Oscillation by the subtropical Indian Ocean Dipole
dc.type journal article
dc.identifier.doi 10.1007/s00382-016-3220-6
dc.identifier.wos WOS:000398926400025


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