The Indian Ocean SST dipole simulated in a coupled general circulation model

Iizuka, Satoshi; Matsuura, Takeshi; Yamagata, Toshio

doi:10.1029/2000gl011484

Cited by 142 publications

(89 citation statements)

References 12 publications

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“…Some authors like Chambers et al (1999); Allan et al (2001); Banquero et al (2002); Dommenget and Latif (2002); Hastenrath (2002); Shinoda et al (2004); Yu and Lau (2004) argue that IODZM events are triggered by ENSO and hence are not independent of ENSO. While on the other hand, others like Webster et al (1999) ;Iizuka et al (2000); Rao et al (2002); Yamagata et al (2002); Ashok et al (2003); Gualdi et al (2003); Lau and Nath (2004); Behera et al (2005) contradict these findings by presenting the independence of the IODZM mode from ENSO. At the same time, Behera and Yamagata (2003); Saji and Yamagata (2003); Ashok et al (2004a); Yamagata et al (2004) also further acknowledged that both phenomena interact with each other.…”

Section: Introductionmentioning

confidence: 94%

“…However, evidence on the physical existence of the IODZM has been amply demonstrated by showing that the IODZM is an internal coupled mode in the IO, which at times co-occurs with ENSO in the Pacific (Saji et al, 1999;Webster et al, 1999;Iizuka et al, 2000;Murtugudde et al, 2000;Rao et al, 2002;Vinayachandran et al, 2002;Yamagata et al, 2002 andAshok et al, 2003). noted that there is evidence on the active role played by the IO on some of the IODZM mode events, but concluded that it is its self-sustainability and impact on regional and global climate that is still a matter of debate.…”

Section: Introductionmentioning

confidence: 99%

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The impact of the positive Indian Ocean dipole on Zimbabwe droughts

Manatsa

Chingombe

Matarira

2008

Intl Journal of Climatology

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A comparative study of the impact of the anomalous positive Indian Ocean SST gradient, referred to as the Indian Ocean Dipole/Zonal Mode (IODZM), and El Niño-Southern Oscillation (ENSO) on Zimbabwe seasonal rainfall variability for the period 1940-1999, is documented. Composite techniques together with simple and partial correlation analyses are employed to segregate the unique association related to IODZM/ENSO with respect to the Zimbabwe seasonal rainfall.The analysis reveals that the IODZM impact on the country's summer rainfall is overwhelming as compared to that of ENSO when the two are in competition. The IODZM influence remains high (significant above 99% confidence level), even after the influence of ENSO has been removed, while that of ENSO collapses to insignificance (even at 90% confidence level) when the IODZM contribution is eliminated. The relationship between ENSO and Zimbabwe seasonal rainfall seems to be sustained through El Niño occurring in the presence of positive IODZM events. However, when the co-occurring positive IODZM and El Niño events are removed from the analysis, it is apparently clear that ENSO has little to do with the country's rainfall variability. On the other hand, positive IODZM is mostly associated with the rainfall deficits, whether or not it co-occurs with El Niño. However, the co-occurrence of the two events does not necessarily suggest that El Niño influences droughts through the positive IODZM events. The El Niño event components during co-occurrence seem to be unrelated (at least linearly) to the droughts, while the positive IODZM events display a relatively strong relationship that is significant above the 95% confidence level. It thus becomes important to extend the study of this nature to cover the whole of southern Africa, so that the extent of the impact of the phenomena can be realized over the whole region.

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Section: Introductionmentioning

confidence: 94%

Section: Introductionmentioning

confidence: 99%

The impact of the positive Indian Ocean dipole on Zimbabwe droughts

Manatsa

Chingombe

Matarira

2008

Intl Journal of Climatology

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“…In response to these SST changes, cooler waters in the eastern IO give rise to easterly winds along the equator, enhancing the cooling in the eastern equatorial IO and promoting warming in the western equatorial IO (Webster et al, 1999;Saji and Yamagata, 2003b). Further, in response to this, convection over the eastern (western) tropical IO is suppressed (enhanced) as the easterly wind anomaly over the central IO is intensified (Iizuka et al, 2000). This state of the IO is identified as a positive IODM event, which develops rapidly in boreal summer and peaks in boreal autumn.…”

Section: Iodm and Its Variabilitymentioning

confidence: 99%

Northeast monsoon rainfall variability over south peninsular India vis‐à‐vis the Indian Ocean dipole mode

Kripalani

Kumar

2004

Intl Journal of Climatology

185

141

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Whereas the June through to September southwest summer monsoon season over the Indian subcontinent has been the main focus of research, the October through to December northeast monsoon season over south peninsular India has received less attention. Hence, this study focuses on the northeast monsoon rainfall (NEMR) variability using historical data for a 131 year period and its relationship with the neighbouring Indian Ocean sea-surface temperature (SST).Based on the observed available rainfall data, a time series of NEMR over the coherent south peninsular India has been developed. Similarly, an index to quantify the Indian Ocean dipole mode (IODM), exhibiting warm (cool) waters over the equatorial western (southeastern) Indian Ocean, has been developed using GISST data for the same period. The dynamics of the NEMR-IODM relationship are examined with the National Centers for Environmental Prediction-National Center for Atmospheric Research reanalysis data.Interannual and decadal variabilities in NEMR reveal alternate epochs of above-and below-normal rainfall. The epochs tend to last for about a decade or two. Rainfall epochs near the equatorial Indian Ocean tend to last for about a decade. No long-term trends in NEMR are noted. On the other hand, the decadal variability in the IODM reveals a dominance of the negative phase during the earlier decades (1880-1920) and a positive phase during recent decades , with suppressed activity in between. Long-term variability in the IODM clearly reveals an increasing trend, which could be related to greenhouse warming. Further, the NEMR variability is enhanced during the decades when the IODM exhibits its active phase, and is suppressed during the decades when the IODM is inactive.The NEMR and the IODM are directly related, suggesting that the positive (negative) phase enhances (suppresses) the northeast monsoon activity. During the positive phase, the anomalous flow pattern shows winds converging and suggesting moisture transport from the southeast Indian Ocean and the Bay of Bengal towards south peninsular India. In contrast, the negative phase reveals winds diverging and transporting moisture away from the south Indian region. The anomalous SST and circulation features associated with the positive IOD/excess rainfall and negative IOD/deficient rainfall are consistent and clearly bring out the coupled ocean-atmosphere dynamics over the Indian Ocean. These results show the direct influence of the IODM phenomenon on the interannual and decadal NEMR variability over south India.

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“…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: 96%

Influence of the Indian Ocean Dipole on the Southern Oscillation.

Behera¹,

Yamagata²

2003

Journal of the Meteorological Society of Japan

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200

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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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The Indian Ocean SST dipole simulated in a coupled general circulation model

Cited by 142 publications

References 12 publications

The impact of the positive Indian Ocean dipole on Zimbabwe droughts

The impact of the positive Indian Ocean dipole on Zimbabwe droughts

Northeast monsoon rainfall variability over south peninsular India vis‐à‐vis the Indian Ocean dipole mode

Influence of the Indian Ocean Dipole on the Southern Oscillation.

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