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| Titel |
Role of the Indonesian Throughflow in controlling regional mean climate and rainfall variability |
| VerfasserIn |
Matthew H. England, Agus Santoso, Steven Phipps, Caroline Ummenhofer |
| Konferenz |
EGU General Assembly 2017
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250147435
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| Publikation (Nr.) |
 EGU/EGU2017-11600.pdf |
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| Zusammenfassung |
| The role of the Indonesian Throughflow (ITF) in controlling regional mean climate and
rainfall is examined using a coupled ocean-atmosphere general circulation model.
Experiments employing both a closed and open ITF are equilibrated to steady state and then
200 years of natural climatic variability is assessed within each model run, with a particular
focus on the Indian Ocean region. Opening of the ITF results in a mean Pacific-to-Indian
throughflow of 21 Sv (1 Sv = 106 m3 sec−1), which advects warm west Pacific
waters into the east Indian Ocean. This warm signature is propagated westward
by the mean ocean flow, however it never reaches the west Indian Ocean, as an
ocean-atmosphere feedback in the tropics generates a weakened trade wind field that is
reminiscent of the negative phase of the Indian Ocean Dipole (IOD). This is in marked
contrast to the Indian Ocean response to an open ITF when examined in ocean-only
model experiments; which sees a strengthening of both the Indian Ocean South
Equatorial Current and the Agulhas Current. The coupled feedback in contrast
leads to cooler conditions over the west Indian Ocean, and an anomalous zonal
atmospheric pressure gradient that enhances the advection of warm moist air toward south
Asia and Australia. This leaves the African continent significantly drier, and much
of Australia and southern Asia significantly wetter, in response to the opening of
the ITF. Given the substantial interannual variability that the ITF exhibits in the
present-day climate system, and the restriction of the ITF gateway in past climate
eras, this could have important implications for understanding past and present
regional rainfall patterns around the Indian Ocean and over neighbouring land-masses. |
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