Indian Ocean subtropical dipole simulated using a coupled general circulation model

Suzuki, Riéko; Behera, Swadhin K.; Iizuka, Satoshi; Yamagata, Toshio

doi:10.1029/2003jc001974

Cited by 96 publications

(90 citation statements)

References 24 publications

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“…In the south Indian Ocean, a subtropical dipole has also been identified in interannual SSTa with peak development in austral summer (Behera and Yamagata 2001;Suzuki et al 2004). A positive phase is characterized by warm SSTa in the southwestern Indian Ocean south of Madagascar and cold SSTa in the eastern Indian Ocean off Australia.…”

Section: Subtropical Dipole and Sea Level Patternsmentioning

confidence: 97%

Spatial Patterns of Sea Level Variability Associated with Natural Internal Climate Modes

et al. 2016

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Sea level rise (SLR) can exert significant stress on highly populated coastal societies and low-lying island countries around the world. Because of this, there is huge societal demand for improved decadal predictions and future projections of SLR, particularly on a local scale along coastlines. Regionally, sea level variations can deviate considerably from the global mean due to various geophysical processes. These include changes of ocean circulations, which partially can be attributed to natural, internal modes of variability in the complex Earth's climate system. Anthropogenic influence may also contribute to regional sea level variations. Separating the effects of natural climate modes and anthropogenic forcing, however, remains a challenge and requires identification of the imprint of specific climate modes in observed sea level change patterns. In this paper, we review our current state of knowledge about spatial patterns of sea level variability associated with natural climate modes on interannual-to-multidecadal timescales, with particular focus on decadal-to-multidecadal variability. Relevant climate modes and our current state of understanding their associated sea level patterns and driving mechanisms are elaborated separately for the Pacific, the Indian, the Atlantic, and the Arctic and Southern Oceans. We also discuss the issues, challenges and future outlooks for understanding the regional sea level patterns associated with climate modes. Effects of these internal modes have to be taken into account in order to achieve more reliable near-term predictions and future projections of regional SLR.

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Section: Subtropical Dipole and Sea Level Patternsmentioning

confidence: 97%

Spatial Patterns of Sea Level Variability Associated with Natural Internal Climate Modes

et al. 2016

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“…Neither of these two poles overlies the regions of high SST anomaly identified above. It is not surprising then, that the subtropical dipole index (SDI) of Suzuki et al (2004) is not significantly correlated with SWWA rainfall (Pearson correlation coefficient of 0.238, and an associated P value of 0.183). Similar correlation levels are obtained between SWWA rainfall and the SDI of Behera and Yamagata (2001).…”

Section: E Relation To the Iod And Siodmentioning

confidence: 99%

“…5 the location of these anomalies does not match previous definitions of the SIOD. For example, Suzuki et al (2004) investigate a subtropical dipole of SST at 42°-30°S, 50°-80°E, (southwestern pole) and 29°-17°S, 75°-105°E (northeastern pole). Neither of these two poles overlies the regions of high SST anomaly identified above.…”

Section: E Relation To the Iod And Siodmentioning

confidence: 99%

Interannual Rainfall Extremes over Southwest Western Australia Linked to Indian Ocean Climate Variability

2006

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Interannual rainfall extremes over southwest Western Australia (SWWA) are examined using observations, reanalysis data, and a long-term natural integration of the global coupled climate system. The authors reveal a characteristic dipole pattern of Indian Ocean sea surface temperature (SST) anomalies during extreme rainfall years, remarkably consistent between the reanalysis fields and the coupled climate model but different from most previous definitions of SST dipoles in the region. In particular, the dipole exhibits peak amplitudes in the eastern Indian Ocean adjacent to the west coast of Australia. During dry years, anomalously cool waters appear in the tropical/subtropical eastern Indian Ocean, adjacent to a region of unusually warm water in the subtropics off SWWA. This dipole of anomalous SST seesaws in sign between dry and wet years and appears to occur in phase with a large-scale reorganization of winds over the tropical/subtropical Indian Ocean. The wind field alters SST via anomalous Ekman transport in the tropical Indian Ocean and via anomalous air-sea heat fluxes in the subtropics. The winds also change the large-scale advection of moisture onto the SWWA coast. At the basin scale, the anomalous wind field can be interpreted as an acceleration (deceleration) of the Indian Ocean climatological mean anticyclone during dry (wet) years. In addition, dry (wet) years see a strengthening (weakening) and coinciding southward (northward) shift of the subpolar westerlies, which results in a similar southward (northward) shift of the rainbearing fronts associated with the subpolar front. A link is also noted between extreme rainfall years and the Indian Ocean Dipole (IOD). Namely, in some years the IOD acts to reinforce the eastern tropical pole of SST described above, and to strengthen wind anomalies along the northern flank of the Indian Ocean anticyclone. In this manner, both tropical and extratropical processes in the Indian Ocean generate SST and wind anomalies off SWWA, which lead to moisture transport and rainfall extremes in the region. An analysis of the seasonal evolution of the climate extremes reveals a progressive amplification of anomalies in SST and atmospheric circulation toward a wintertime maximum, coinciding with the season of highest SWWA rainfall. The anomalies in SST can appear as early as the summertime months, however, which may have important implications for predictability of SWWA rainfall extremes.

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“…2a). Many studies on the variability of the location and strength of the Mascarene High (Terray et al 2003;Suzuki et al 2004;Xue et al 2004;Fischer et al 2005;Feng et al 2013;Manatsa et al 2014;Morioka et al 2015) have noted that the Mascarene High influences monsoonal flow and SST variation over the Indian Ocean. According to the large-scale environmental conditions shown here, the weakening and southward shift of the Mascarene High could be one of the favorable environmental conditions enabling the MJO onset to break the convective suppressed period of P1 over the equatorial Indian Ocean.…”

Section: Large-scale Environmental Conditions Aroundmentioning

confidence: 99%

Equatorially Antisymmetric Features in the Initiation Processes of the Madden-Julian Oscillation Observed in Late October during CINDY2011

Moteki

2015

Journal of the Meteorological Society of Japan

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In this study, we investigated the equatorially antisymmetric features in the initiation processes of the MaddenJulian oscillation (MJO) event in late October during the cooperative Indian Ocean experiment on intraseasonal variability in the year 2011. This MJO event developed when the thermal equator was drastically shifted from the Northern Hemisphere to the equator from September to October as the Mascarene High over the southern Indian Ocean decayed and shifted southward. The large-scale fields of sea level pressure, temperature, and moisture around the MJO exhibited equatorially antisymmetric features. According to their different features in terms of surface convergence, temperature, and moisture, MJO convection over the Indian Ocean after its onset consisted of four distinct convective components: the southern intertropical convergence zone between 10°S and 0° along the meridional sea surface temperature (SST) gradients (s-ITCZ), the northern-ITCZ at the southern edge of the high SST above 29°C over the Bay of Bengal, the vortex disturbance over the Arabian Sea (VDAS) in association with the zonal SST gradients, and the westward-propagating diurnal convection originating from Sumatra. In particular, the double-ITCZ and VDAS were characterized by a steady, low-level convergence zone along the surface potential temperature gradients forced by the SST. Before the onset of the MJO convection, the double-ITCZ was characterized by cross-equatorial vertical circulation that was baroclinically tilted northward, and s-ITCZ convection was inhibited owing to the strong Mascarene High. After the onset, single, larger-scale upward motion was barotropically formed over the equator because of the equatorward shift of the double-ITCZ. Such changes in the equatorially antisymmetric meridional circulation are relevant for the organization of the MJO convection.

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Indian Ocean subtropical dipole simulated using a coupled general circulation model

Cited by 96 publications

References 24 publications

Spatial Patterns of Sea Level Variability Associated with Natural Internal Climate Modes

Spatial Patterns of Sea Level Variability Associated with Natural Internal Climate Modes

Interannual Rainfall Extremes over Southwest Western Australia Linked to Indian Ocean Climate Variability

Equatorially Antisymmetric Features in the Initiation Processes of the Madden-Julian Oscillation Observed in Late October during CINDY2011

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