Strengthening of the Indian Ocean Dipole With Increasing Seasonal Cycle in the Mid‐Holocene

Discovered at the very end of the 20th century, the Indian Ocean Dipole (IOD) is a mode of natural climate variability that arises out of coupled ocean–atmosphere interaction in the Indian Ocean. It is associated with some of the largest changes of ocean–atmosphere state over the equatorial Indian Ocean on interannual time scales. IOD variability is prominent during the boreal summer and fall seasons, with its maximum intensity developing at the end of the boreal-fall season. Between the peaks of its negative and positive phases, IOD manifests a markedly zonal see-saw in anomalous sea surface temperature (SST) and rainfall—leading, in its positive phase, to a pronounced cooling of the eastern equatorial Indian Ocean, and a moderate warming of the western and central equatorial Indian Ocean; this is accompanied by deficit rainfall over the eastern Indian Ocean and surplus rainfall over the western Indian Ocean. Changes in midtropospheric heating accompanying the rainfall anomalies drive wind anomalies that anomalously lift the thermocline in the equatorial eastern Indian Ocean and anomalously deepen them in the central Indian Ocean. The thermocline anomalies further modulate coastal and open-ocean upwelling, thereby influencing biological productivity and fish catches across the Indian Ocean. The hydrometeorological anomalies that accompany IOD exacerbate forest fires in Indonesia and Australia and bring floods and infectious diseases to equatorial East Africa. The coupled ocean–atmosphere instability that is responsible for generating and sustaining IOD develops on a mean state that is strongly modulated by the seasonal cycle of the Austral-Asian monsoon; this setting gives the IOD its unique character and dynamics, including a strong phase-lock to the seasonal cycle. While IOD operates independently of the El Niño and Southern Oscillation (ENSO), the proximity between the Indian and Pacific Oceans, and the existence of oceanic and atmospheric pathways, facilitate mutual interactions between these tropical climate modes.

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Analysis of Drought-Sensitive Areas and Evolution Patterns through Statistical Simulations of the Indian Ocean Dipole Mode

Water ◽

10.3390/w11061302 ◽

2019 ◽

Vol 11 (6) ◽

pp. 1302 ◽

Cited By ~ 2

Author(s):

Qing-Gang Gao ◽

Vonevilay Sombutmounvong ◽

Lihua Xiong ◽

Joo-Heon Lee ◽

Jong-Suk Kim

Keyword(s):

Indian Ocean ◽

Indian Ocean Dipole ◽

Diagnostic Techniques ◽

Eastern Coast ◽

Indochina Peninsula ◽

Indian Ocean Dipole Mode ◽

Sensitive Areas ◽

The Indian Ocean ◽

Long Term Trend

In this study, we investigated extreme droughts in the Indochina peninsula and their relationship with the Indian Ocean Dipole (IOD) mode. Areas most vulnerable to drought were analyzed via statistical simulations of the IOD based on historical observations. Results of the long-term trend analysis indicate that areas with increasing spring (March–May) rainfall are mainly distributed along the eastern coast (Vietnam) and the northwestern portions of the Indochina Peninsula (ICP), while Central and Northern Laos and Northern Cambodia have witnessed a reduction in spring rainfall over the past few decades. This trend is similar to that of extreme drought. During positive IOD years, the frequency of extreme droughts was reduced throughout Vietnam and in the southwestern parts of China, while increased drought was observed in Cambodia, Central Laos, and along the coastline adjacent to the Myanmar Sea. Results for negative IOD years were similar to changes observed for positive IOD years; however, the eastern and northern parts of the ICP experienced reduced droughts. In addition, the results of the statistical simulations proposed in this study successfully simulate drought-sensitive areas and evolution patterns of various IOD changes. The results of this study can help improve diagnostic techniques for extreme droughts in the ICP.

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Influence of the Indian Ocean Dipole on tree-ring δ18O of monsoonal Southeast Tibet

Climatic Change ◽

10.1007/s10584-016-1663-8 ◽

2016 ◽

Vol 137 (1-2) ◽

pp. 217-230 ◽

Cited By ~ 14

Author(s):

Philipp Hochreuther ◽

Jakob Wernicke ◽

Jussi Grießinger ◽

Thomas Mölg ◽

Haifeng Zhu ◽

...

Keyword(s):

Indian Ocean ◽

Tree Ring ◽

Indian Ocean Dipole ◽

The Indian Ocean ◽

Southeast Tibet

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Two Independent Triggers for the Indian Ocean Dipole/Zonal Mode in a Coupled GCM

Journal of Climate ◽

10.1175/jcli3478.1 ◽

2005 ◽

Vol 18 (17) ◽

pp. 3428-3449 ◽

Cited By ~ 114

Author(s):

Albert S. Fischer ◽

Pascal Terray ◽

Eric Guilyardi ◽

Silvio Gualdi ◽

Pascale Delecluse

Keyword(s):

Indian Ocean ◽

El Niño ◽

Indian Ocean Dipole ◽

El Nino ◽

Tropical Indian Ocean ◽

Sea Surface ◽

Dynamical Response ◽

Thermocline Depth ◽

Second Phase ◽

The Indian Ocean

Abstract The question of whether and how tropical Indian Ocean dipole or zonal mode (IOZM) interannual variability is independent of El Niño–Southern Oscillation (ENSO) variability in the Pacific is addressed in a comparison of twin 200-yr runs of a coupled climate model. The first is a reference simulation, and the second has ENSO-scale variability suppressed with a constraint on the tropical Pacific wind stress. The IOZM can exist in the model without ENSO, and the composite evolution of the main anomalies in the Indian Ocean in the two simulations is virtually identical. Its growth depends on a positive feedback between anomalous equatorial easterly winds, upwelling equatorial and coastal Kelvin waves reducing the thermocline depth and sea surface temperature off the coast of Sumatra, and the atmospheric dynamical response to the subsequently reduced convection. Two IOZM triggers in the boreal spring are found. The first is an anomalous Hadley circulation over the eastern tropical Indian Ocean and Maritime Continent, with an early northward penetration of the Southern Hemisphere southeasterly trades. This situation grows out of cooler sea surface temperatures in the southeastern tropical Indian Ocean left behind by a reinforcement of the late austral summer winds. The second trigger is a consequence of a zonal shift in the center of convection associated with a developing El Niño, a Walker cell anomaly. The first trigger is the only one present in the constrained simulation and is similar to the evolution of anomalies in 1994, when the IOZM occurred in the absence of a Pacific El Niño state. The presence of these two triggers—the first independent of ENSO and the second phase locking the IOZM to El Niño—allows an understanding of both the existence of IOZM events when Pacific conditions are neutral and the significant correlation between the IOZM and El Niño.

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Oceanic Influences on the Seasonal Cycle in Evaporation over the Indian Ocean

Journal of Climate ◽

10.1175/1520-0442(2001)014<1199:oiotsc>2.0.co;2 ◽

2001 ◽

Vol 14 (6) ◽

pp. 1199-1226 ◽

Cited By ~ 19

Author(s):

Roxana C. Wajsowicz ◽

Paul S. Schopf

Keyword(s):

Indian Ocean ◽

Seasonal Cycle ◽

The Indian Ocean

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

SOLA ◽

10.2151/sola.2011-004 ◽

2011 ◽

Vol 7 ◽

pp. 13-16 ◽

Cited By ~ 5

Author(s):

Toru Tamura ◽

Toshio Koike ◽

Akio Yamamoto ◽

Masaki Yasukawa ◽

Masaru Kitsuregawa

Keyword(s):

Indian Ocean ◽

Indian Ocean Dipole ◽

Tropospheric Biennial Oscillation ◽

The Indian Ocean ◽

Biennial Oscillation

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Modulation of the Ganges‐Brahmaputra River Plume by the Indian Ocean Dipole and Eddies Inferred From Satellite Observations

Journal of Geophysical Research Oceans ◽

10.1002/2017jc013333 ◽

2017 ◽

Vol 122 (12) ◽

pp. 9591-9604 ◽

Cited By ~ 21

Author(s):

S. Fournier ◽

J. Vialard ◽

M. Lengaigne ◽

T. Lee ◽

M. M. Gierach ◽

...

Keyword(s):

Indian Ocean ◽

Indian Ocean Dipole ◽

River Plume ◽

Satellite Observations ◽

Brahmaputra River ◽

The Indian Ocean ◽

The Ganges

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How Predictable is the Indian Ocean Dipole?

Monthly Weather Review ◽

10.1175/mwr-d-12-00001.1 ◽

2012 ◽

Vol 140 (12) ◽

pp. 3867-3884 ◽

Cited By ~ 60

Author(s):

Li Shi ◽

Harry H. Hendon ◽

Oscar Alves ◽

Jing-Jia Luo ◽

Magdalena Balmaseda ◽

...

Keyword(s):

Indian Ocean ◽

Surface Temperature ◽

Indian Ocean Dipole ◽

Lead Time ◽

Research Centre ◽

Model Errors ◽

Seasonal Forecasts ◽

Forecast System ◽

Predictive Skill ◽

The Indian Ocean

Abstract In light of the growing recognition of the role of surface temperature variations in the Indian Ocean for driving global climate variability, the predictive skill of the sea surface temperature (SST) anomalies associated with the Indian Ocean dipole (IOD) is assessed using ensemble seasonal forecasts from a selection of contemporary coupled climate models that are routinely used to make seasonal climate predictions. The authors assess predictions from successive versions of the Australian Bureau of Meteorology Predictive Ocean–Atmosphere Model for Australia (POAMA 15b and 24), successive versions of the NCEP Climate Forecast System (CFSv1 and CFSv2), the ECMWF seasonal forecast System 3 (ECSys3), and the Frontier Research Centre for Global Change system (SINTEX-F) using seasonal hindcasts initialized each month from January 1982 to December 2006. The lead time for skillful prediction of SST in the western Indian Ocean is found to be about 5–6 months while in the eastern Indian Ocean it is only 3–4 months when all start months are considered. For the IOD events, which have maximum amplitude in the September–November (SON) season, skillful prediction is also limited to a lead time of about one season, although skillful prediction of large IOD events can be longer than this, perhaps up to about two seasons. However, the tendency for the models to overpredict the occurrence of large events limits the confidence of the predictions of these large events. Some common model errors, including a poor representation of the relationship between El Niño and the IOD, are identified indicating that the upper limit of predictive skill of the IOD has not been achieved.

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Triggering the Indian Ocean Dipole from the Southern Hemisphere

10.5194/egusphere-egu21-3655 ◽

2021 ◽

Author(s):

Lian-Yi Zhang ◽

Yan Du ◽

Wenju Cai ◽

Zesheng Chen ◽

Tomoki Tozuka ◽

...

Keyword(s):

Indian Ocean ◽

Southern Hemisphere ◽

Indian Ocean Dipole ◽

Southern Oscillation ◽

Southern Annular Mode ◽

Triggering Mechanism ◽

Phase Development ◽

The Indian Ocean ◽

High System ◽

The Tropics

<p>This study identifies a new triggering mechanism of the Indian Ocean Dipole (IOD) from the Southern Hemisphere. This mechanism is independent from the El Ni&#241;o/Southern Oscillation (ENSO) and tends to induce the IOD before its canonical peak season. The joint effects of this mechanism and ENSO may explain different lifetimes and strengths of the IOD. During its positive phase, development of sea surface temperature cold anomalies commences in the southern Indian Ocean, accompanied by an anomalous subtropical high system and anomalous southeasterly winds. The eastward movement of these anomalies enhances the monsoon off Sumatra-Java during May-August, leading to an early positive IOD onset. The pressure variability in the subtropical area is related with the Southern Annular Mode, suggesting a teleconnection between high-latitude and mid-latitude climate that can further affect the tropics. To include the subtropical signals may help model prediction of the IOD event.</p>

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Optimized coral reconstructions of the Indian Ocean Dipole: An assessment of location and length considerations

Paleoceanography ◽

10.1002/2015pa002810 ◽

2015 ◽

Vol 30 (10) ◽

pp. 1391-1405 ◽

Cited By ~ 4

Author(s):

Nerilie J. Abram ◽

Bronwyn C. Dixon ◽

Madelaine G. Rosevear ◽

Benjamin Plunkett ◽

Michael K. Gagan ◽

...

Keyword(s):

Indian Ocean ◽

Indian Ocean Dipole ◽

The Indian Ocean

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