Unusual ocean‐atmosphere conditions in the tropical Indian Ocean during 1994

Behera, Swadhin K.; Krishnan, R.; Yamagata, Toshio

doi:10.1029/1999gl010434

Cited by 302 publications

(232 citation statements)

References 13 publications

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“…The convection in the eastern Indian Ocean is suppressed during the positive IOD events, whereas the convection in the central and western Indian Ocean is enhanced. Behera et al (1999) have shown that the coupling between the SST cooling and the suppressed convection in the eastern Indian Ocean gave rise to further easterly wind anomalies during the typical IOD event of 1994. Using a simple Matsuno-Gill type model, Saji and Yamagata (2001) have also shown that the atmospheric linear response to such changes in the heat source of the eastern Indian Ocean strengthens the easterly wind anomalies, which in turn are responsible for the evolution of the SST dipole.…”

Section: Introductionmentioning

confidence: 99%

“…The effect of the wind is even more significant at the thermocline depths through the oceanic adjustment process ; the thermocline rises in the east and deepens in the central and western parts. Since the seasonal southeasterly winds along the Sumatra coast are also strengthened during the positive IOD events, the induced coastal upwelling causes strong SST cooling in the east (Behera et al 1999).…”

Section: Introductionmentioning

confidence: 99%

“…Hence, they concluded that the El Niñ o and Southern Oscillation are more loosely coupled than numerous past studies would suggest. The motivation of the present short article is due to the fact that the Indian Ocean Dipole (IOD) discovered recently (Saji et al 1999;Webster et al 1999;Behera et al 1999;Iizuka et al 2000;Yamagata et al 2002), has suggested a new role of the Indian Ocean in determining the sea level pressure oscillation over the Asia-Pacific sector. Since its existence has come to the light very recently, a brief description of the Indian Ocean phenomenon is provided here.…”

Section: Introductionmentioning

confidence: 99%

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Influence of the Indian Ocean Dipole on the Southern Oscillation.

Behera¹,

Yamagata²

2003

Journal of the Meteorological Society of Japan

201

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The influence of the Indian Ocean Dipole (IOD) on the interannual atmospheric pressure variability of the Indo-Pacific sector is investigated. Statistical correlation between the IOD index and the global sea level pressure anomalies demonstrates that loadings of opposite polarity occupy the western and the eastern parts of the Indian Ocean. The area of positive correlation coefficient in the eastern part even extends to the Australian region, and the IOD index has a peak correlation coefficient of about 0.4 with the Darwin pressure index, i.e. the western pole of the Southern Oscillation, when the former leads the latter by one month. The correlation analysis with seasonally stratified data further confirms the lead role of the IOD. The IOD-Darwin relation has undergone interdecadal changes; in the last 50 years the correlation is highest during the most recent decade of 1990-99, and weakest during 1980-89.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Influence of the Indian Ocean Dipole on the Southern Oscillation.

Behera¹,

Yamagata²

2003

Journal of the Meteorological Society of Japan

201

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“…Figures 1a-1e demonstrate that, the IOD SSTA pattern indeed exists during JJAS season of aforementioned dipole years, and the Boxes A and B reasonably represent the two different poles of the IOD. Study of some recent dipole events suggests that IOD is an air-sea interaction phenomenon (Behera et al 1999;Webster et al 1999). When the IODMI is positive, it may lead to droughts over the Indonesian region, while simultaneously causing heavy rains and floods over East Africa.…”

Section: Introductionmentioning

confidence: 99%

Summertime Response of the Tropical Atmosphere to the Indian Ocean Dipole Sea Surface Temperature Anomalies

Guan

Ashok

Yamagata

2003

Journal of the Meteorological Society of Japan

100

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The anomalous response of the tropical atmosphere to the recently discovered Indian Ocean Dipole has been studied in the present article, using an Atmospheric General Circulation Model (AGCM), and the NCEP/ NCAR Reanalysis. Our AGCM study shows that the response of the atmosphere to the IOD is of dipole-like pattern in the circulation, and is baroclinic. An anomalous circulation in the zonalvertical plane is induced, with the subsidence over colder pole and the upward motion over the warmer pole, modulating the Walker circulation over the equatorial Indian Ocean, as observed. An anomalous circulation in the meridional-vertical plane from the eastern pole of the dipole towards India, and the Bay of Bengal is simulated, which affects the Indian summer monsoon rainfall. The model atmosphere is heated by the anomalous surplus of the latent heat, the net long-wave radiation, and sensible heat fluxes over the warmer pole of the IOD. This results in an excess of net vertically integrated moisture convergence, and excess latent heat release in the atmospheric column above the warm pole. This energy, together with the anomalous convergence of enthalpy, is converted into anomalous mechanical energy and leads to the divergence of mechanical energy flux. This anomalous divergence of the mechanical energy in the upper tropospheric part of the column causes propagation of the disturbances to the surrounding regions. The mean seasonal circulation during the boreal summer is crucial for maintenance of the anomalous energy distribution and propagation during the IOD event. Transient high frequency variability does not appear to contribute much to the energy conversions.

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“…During the 1990s, the well-established link between El Niño and the Indian monsoon failed. In 1994, the southeast tropical Indian Ocean experienced unusually cold SSTs and southeasterly winds (Behera et al, 1999 Figure 9. Schematic of the Atlantic coupled mode and its feedbacks, showing the warm phase leading to a succeeding cold phase a combination of enhanced upwelling along the eastern shore of the Indian Ocean with evaporative cooling offshore, atmosphere convection was suppressed in the region.…”

Section: Tropical Air-sea Coupling In the Atlantic And Indian Oceansmentioning

confidence: 99%

The role of the oceans in climate

Bigg

Jickells

Liss

et al. 2003

Intl Journal of Climatology

126

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The ocean is increasingly seen as a vital component of the climate system. It exchanges with the atmosphere large quantities of heat, water, gases, particles and momentum. It is an important part of the global redistribution of heat from tropics to polar regions keeping our planet habitable, particularly equatorward of about 30°. In this article we review recent work examining the role of the oceans in climate, focusing on research in the Third Assessment Report of the IPCC and later. We discuss the general nature of oceanic climate variability and the large role played by stochastic variability in the interaction of the atmosphere and ocean. We consider the growing evidence for biogeochemical interaction of climatic significance between ocean and atmosphere. Air-sea exchange of several radiatively important gases, in particular CO 2 , is a major mechanism for altering their atmospheric concentrations. Some more reactive gases, such as dimethyl sulphide, can alter cloud formation and hence albedo. Particulates containing iron and originating over land can alter ocean primary productivity and hence feedbacks to other biogeochemical exchanges. We show that not only the tropical Pacific Ocean basin can exhibit coupled ocean-atmosphere interaction, but also the tropical Atlantic and Indian Oceans. Longer lived interactions in the North Pacific and Southern Ocean (the circumpolar wave) are also reviewed. The role of the thermohaline circulation in long-term and abrupt climatic change is examined, with the freshwater budget of the ocean being a key factor for the degree, and longevity, of change. The potential for the Mediterranean outflow to contribute to abrupt change is raised. We end by examining the probability of thermohaline changes in a future of global warming.

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Unusual ocean‐atmosphere conditions in the tropical Indian Ocean during 1994

Cited by 302 publications

References 13 publications

Influence of the Indian Ocean Dipole on the Southern Oscillation.

Influence of the Indian Ocean Dipole on the Southern Oscillation.

Summertime Response of the Tropical Atmosphere to the Indian Ocean Dipole Sea Surface Temperature Anomalies

The role of the oceans in climate

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