Pacific Ocean Contribution to the Asymmetry in Eastern Indian Ocean Variability.

Ummenhofer, Caroline C., Schwarzkopf, Franziska U. , Meyers, Gary, Behrens, Erik, Biastoch, Arne and Böning, Claus W. (2013) Pacific Ocean Contribution to the Asymmetry in Eastern Indian Ocean Variability. Open Access Journal of Climate, 26 . pp. 1152-1171. DOI 10.1175/JCLI-D-11-00673.1.

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Abstract

Variations in eastern Indian Ocean upper-ocean thermal properties are assessed for the period 1970–2004, with a particular focus on asymmetric features related to opposite phases of Indian Ocean Dipole events, using high-resolution ocean model hindcasts. Sensitivity experiments, where atmospheric forcing variability is restricted to the Indian or Pacific Ocean only, support the interpretation of forcing mechanisms for large-scale asymmetric behavior in eastern Indian Ocean variability. Years are classified according to eastern Indian Ocean subsurface heat content (HC) as proxy of thermocline variations. Years characterized by anomalous low HC feature a zonal gradient in upper-ocean properties near the equator, while high events have a meridional gradient from the tropics into the subtropics. The spatial and temporal characteristics of the seasonal evolution of HC anomalies for the two cases is distinct, as is the relative contribution from Indian Ocean atmospheric forcing versus remote influences from Pacific wind forcing: low events develop rapidly during austral winter/spring in response to Indian Ocean wind forcing associated with an enhanced southeasterly monsoon driving coastal upwelling and a shoaling thermocline in the east; in contrast, formation of anomalous high eastern Indian Ocean HC is more gradual, with anomalies earlier in the year expanding from the Indonesian Throughflow (ITF) region, initiated by remote Pacific wind forcing and transmitted through the ITF via coastal wave dynamics. Implications for seasonal predictions arise with high HC events offering extended lead times for predicting thermocline variations and upper-ocean properties across the eastern Indian Ocean.

Document Type: Article
Additional Information: WOS:000315466700004
Keywords: Rainfall; SST; Sea surface temperature; mode; Pacific Ocean; Dipole; Eastern Indian Ocean Variability; Indonesian throughflow; events; La-Nina; El Nino; Enso; anomalies
Research affiliation: OceanRep > The Future Ocean - Cluster of Excellence
OceanRep > SFB 754
OceanRep > SFB 754 > A2
OceanRep > GEOMAR > FB1 Ocean Circulation and Climate Dynamics > FB1-TM Theory and Modeling
Refereed: Yes
Open Access Journal?: No
DOI etc.: 10.1175/JCLI-D-11-00673.1
ISSN: 0894-8755
Projects: SFB754, Future Ocean
Expeditions/Models/Experiments:
Date Deposited: 26 Nov 2012 07:09
Last Modified: 23 Sep 2019 17:02
URI: http://oceanrep.geomar.de/id/eprint/19286

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