Contrasting Impacts of the Indian Ocean Dipole and ENSO on the Tropospheric Biennial Oscillation

Tamura, Takeshi; Koike, Takao; Yamamoto, Akio; Yasukawa, Masaki

doi:10.2151/sola.2011-004

Cited by 6 publications

(3 citation statements)

References 31 publications

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“…Based on these results and analyses of biennial relations between ENSO, IOD and the Indian Monsoon, we propose a slightly revised scenario of Indo-Pacific interactions (Fig. 12), more consistent with observations (see also Tamura et al 2011), compared to the Tropical Tropospheric Biennial Oscillation (TBO) or Webster and Hoyos (2010) frameworks. In the framework presented here, the IOD-ENSO interactions favour a biennial timescale, and interact with the slower rechargedischarge cycle intrinsic to the Pacific Ocean; but the Indian monsoon responds rather passively to the IOD-ENSO coupled system.…”

Section: Discussionsupporting

confidence: 79%

Influence of Indian Ocean Dipole and Pacific recharge on following year’s El Niño: interdecadal robustness

et al. 2013

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The Indian Ocean Dipole (IOD) can affect the El Niño-Southern Oscillation (ENSO) state of the following year, in addition to the well-known preconditioning by equatorial Pacific Warm Water Volume (WWV), as suggested by a study based on observations over the recent satellite era (1981-2009). The present paper explores the interdecadal robustness of this result over the 1872-2008 period. To this end, we develop a robust IOD index, which well exploits sparse historical observations in the tropical Indian Ocean, and an efficient proxy of WWV interannual variations based on the temporal integral of Pacific wind stress of the 20 th century reanalysis. A linear regression hindcast model based on these two indices in boreal fall explains 50% of ENSO peak variance 14 months later, with significant contributions from both the IOD and WWV over most of the historical period and a similar skill for El Niño and La Niña events. Our results further reveal that, when combined with WWV, the IOD index provides a larger ENSO hindcast skill improvement than the Indian Ocean basin-wide mode, the Indian Monsoon or ENSO itself. Based on these results, we propose a revised scheme of Indo-Pacific interactions. In this scheme, the IOD-ENSO interactions favour a biennial timescale and interact with the slower recharge-discharge cycle intrinsic to the Pacific Ocean.

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Section: Discussionsupporting

confidence: 79%

Influence of Indian Ocean Dipole and Pacific recharge on following year’s El Niño: interdecadal robustness

et al. 2013

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“…The Indian Ocean dipole (IOD) is an intrinsic mode of variability of the tropical Indian Ocean (Saji et al 1999;Webster et al 1999;Murtugudde et al 2000;Ashok et al 2003a;Behera et al 2006;Luo et al 2008Luo et al , 2010Du et al 2013;Wang et al 2016;Saji 2018). It has broad impacts on regional climate (e.g., Ashok et al 2001Ashok et al , 2003bAshok et al , 2004Annamalai and Murtugudde 2004;Li and Mu 2001;Xiao et al 2002;Saji and Yamagata 2003a;Behera et al 2005;Tamura et al 2011;Cherchi and Navarra 2013). An important issue in the studies of IOD is the relationship between IOD and the El Niño-Southern Oscillation (ENSO).…”

Section: Introductionmentioning

confidence: 99%

Covariations between the Indian Ocean dipole and ENSO: a modeling study

et al. 2019

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The coevolution of the Indian Ocean dipole (IOD) and El Niño-Southern Oscillation (ENSO) is examined using both observational data and coupled global climate model simulations. The covariability of IOD and ENSO is analyzed by applying the extended empirical orthogonal function (EEOF) method to the surface and subsurface ocean temperatures in the tropical Indian Ocean and western Pacific. The first EEOF mode shows the evolution of IOD that lags ENSO, whereas the second mode exhibits the transition from a dipole mode to a basinwide mode in the tropical Indian Ocean that leads ENSO. The lead-lag relationships between IOD and ENSO are consistent with two-way interactions between them. A comparison between two 500-year model simulations with and without ENSO shows that ENSO can enhance the variability of IOD at interannual time scale. The influence of ENSO on the IOD intensity is larger for the eastern pole than for the western pole, and further, is stronger in the negative IOD phase than in the positive phase. The influence of IOD on ENSO is demonstrated by the improvement of ENSO prediction using sea surface temperature (SST) in the tropical Indian Ocean as an ENSO precursor. The improvement of the ENSO forecast skill is found at both a short lead time (0 month) and long leads (10-15 months). The SST in the western pole has more predictive value than in the eastern pole. The eastward propagation of surface and subsurface temperature signals from the western Indian Ocean that precedes the development of heat content anomaly in the tropical western Pacific is the key for extending the lead time for ENSO prediction. Our results are consistent with previously reported findings but highlight the spatialtemporal evolution of the ENSO-IOD system. It is also illustrated that IOD would have been more helpful in predicting the 1997/98 El Niño than the 2015/16 El Niño.

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“…The SST anomalies evolution associated with the biennial mode exhibits a strong seasonality in the tropical Pacific and the Indian Oceans (Kim and Kim 2016). The ocean-atmosphere interactions associated with Indian Ocean Dipole (IOD; Saji et al 1999) over the Indo-Pacific sector trigger the biennial phase shift of the ENSO, which in turn could be responsible for the biennial tendency of the Asian summer monsoon (e.g., Annamalai et al 2005;Izumo et al 2010Izumo et al , 2014Sakai et al 2010;Tamura et al 2011). Pillai and Mohankumar (2010) pointed out that the TIO variability such as IOD is important local forcing for the biennial monsoon cycle.…”

Section: Introductionmentioning

confidence: 99%

Tropospheric biennial oscillation and south Asian summer monsoon rainfall in a coupled model

et al. 2018

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In this study Tropospheric Biennial Oscillation (TBO) and south Asian summer monsoon rainfall are examined in the National Centers for Environmental Prediction (NCEP) Climate Forecast System (CFSv2) hindcast. High correlation between the observations and model TBO index suggests that the model is able to capture most of the TBO years. Spatial patterns of rainfall anomalies associated with positive TBO over the south Asian region are better represented in the model as in the observations. However, the model predicted rainfall anomaly patterns associated with negative TBO years are improper and magnitudes are underestimated compared to the observations. It is noted that positive (negative) TBO is associated with La Niña (El Niño) like Sea surface temperature (SST) anomalies in the model. This leads to the fact that model TBO is El Niño-Southern Oscillation (ENSO) driven, while in the observations Indian Ocean Dipole (IOD) also plays a role in the negative TBO phase. Detailed analysis suggests that the negative TBO rainfall anomaly pattern in the model is highly influenced by improper teleconnections allied to IOD. Unlike in the observations, rainfall anomalies over the south Asian region are anti-correlated with IOD index in CFSv2. Further, summer monsoon rainfall over south Asian region is highly correlated with IOD western pole than eastern pole in CFSv2 in contrast to the observations. Altogether, the present study highlights the importance of improving Indian Ocean SST teleconnections to south Asian summer rainfall in the model by enhancing the predictability of TBO. This in turn would improve monsoon rainfall prediction skill of the model.

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Contrasting Impacts of the Indian Ocean Dipole and ENSO on the Tropospheric Biennial Oscillation

Cited by 6 publications

References 31 publications

Influence of Indian Ocean Dipole and Pacific recharge on following year’s El Niño: interdecadal robustness

Influence of Indian Ocean Dipole and Pacific recharge on following year’s El Niño: interdecadal robustness

Covariations between the Indian Ocean dipole and ENSO: a modeling study

Tropospheric biennial oscillation and south Asian summer monsoon rainfall in a coupled model

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