scholarly journals Impact of Preceding El Niño and the Indian Ocean Dipole on the Southern China Precipitation in Early Summer

2014 ◽  
Vol 2014 ◽  
pp. 1-12 ◽  
Author(s):  
Yan Li ◽  
Yafei Wang ◽  
Lin Mu ◽  
Qingyuan Wang ◽  
Jun Song ◽  
...  
Keyword(s):  
Indian Ocean ◽  
El Niño ◽  
Indian Ocean Dipole ◽  
Yangtze River ◽  
El Nino ◽  
Southern China ◽  
The Philippines ◽  
Early Summer ◽  
Single Event ◽  
The Indian Ocean

Delayed impacts of El Niño and the Indian Ocean Dipole in positive phase (P-IOD) on the South China early monsoon were investigated by observations and simulations. The most significant correlation between IOD index (IODI) and NINO3 appeared in boreal autumn. A new index (IODN3) related to the intensity of El Niño and IOD was created. Three indexes in boreal autumn were positively well correlated with the rainfall over the Yangtze River and its southern area (rain-YRBS) in next June. The most significant correlation appeared between IODN3 and rain-YRBS. Positive rain-YRBS anomalies in June tend to occur after P-IOD or El Niño solely matured in previous boreal autumn. However, when both events matured in boreal autumn, rain-YRBS anomalies tended to be more enhanced, which suggests that a delayed combined influence of both events on rain-YRBS in June was larger than that of either event alone. There was a low level anticyclonic circulation around the Philippines (PSAC) that developed in boreal autumn and was maintained until the following June when the single event occurred. However, a much stronger PSAC tended to occur when both events matured. The stronger PSAC could transport more water vapor to YRBS and cause more rainfall there in June.

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

2005 ◽  
Vol 18 (17) ◽  
pp. 3428-3449 ◽  
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.

scholarly journals Seasonal Responses of Precipitation in China to El Niño and Positive Indian Ocean Dipole Modes

Atmosphere ◽  
2019 ◽  
Vol 10 (7) ◽  
pp. 372 ◽  
Author(s):  
Chunxiang Li ◽  
Tianbao Zhao
Keyword(s):  
Indian Ocean ◽  
El Niño ◽  
Indian Ocean Dipole ◽  
North China ◽  
El Nino ◽  
Southern Oscillation ◽  
Southern China ◽  
Northwestern China ◽  
Positive Indian Ocean Dipole ◽  
Seasonal Responses

Using composite, regular, and partial regression analyses in the six consecutive seasons from spring of the El Niño–Southern Oscillation (ENSO)-/Indian Ocean Dipole (IOD)-developing year through summer following the ENSO/IOD mature phase, the individual and combined impacts of El Niño and positive Indian Ocean Dipole (pIOD) on the evolution of precipitation in China are diagnosed for the period 1950–2013. It is shown that the seasonal responses of precipitation in China to El Niño and pIOD events, and their relationship with the large-scale atmospheric circulations, differ from one season to another. For the pure El Niño years, there is a seasonal reversal of precipitation over southeastern and northwestern China, with deficient precipitation occurring in these two regions before the onset of anomalous wet conditions in the developing autumn. Meanwhile, North China tends to be drier than normal in the developing seasons, but wetter than normal in the decaying seasons. For the pure pIOD events, southern China suffers a precipitation deficit (surplus) in the developing spring (summer and autumn). Furthermore, both North China and northwestern China experience excessive precipitation in the developing autumn and decaying summer. In addition, there is reduced precipitation in northeastern China during both the developing and decaying summers, whereas increased precipitation occurs in the developing autumn and decaying winter. For the combined years, southern China experiences enhanced moisture supply and suffers from increased precipitation from the developing summer through the subsequent spring, but reduced precipitation in the developing spring and decaying summer. Similar to the pure El Niño, northwestern (North) China becomes wetter than normal after the developing summer (autumn) in the combined years. In general, the ENSO/IOD-related precipitation variability could be explained by the associated anomaly circulations.

scholarly journals Indian Ocean Dipole and El Niño/Southern Oscillation impacts on regional chlorophyll anomalies in the Indian Ocean

2013 ◽  
Vol 10 (10) ◽  
pp. 6677-6698 ◽  
Author(s):  
J. C. Currie ◽  
M. Lengaigne ◽  
J. Vialard ◽  
D. M. Kaplan ◽  
O. Aumont ◽  
...  
Keyword(s):  
Indian Ocean ◽  
El Niño ◽  
Indian Ocean Dipole ◽  
El Nino ◽  
Southern Oscillation ◽  
El Niño Southern Oscillation ◽  
El Nino Southern Oscillation ◽  
Near Surface ◽  
Climate Modes ◽  
The Indian Ocean

Abstract. The Indian Ocean Dipole (IOD) and the El Niño/Southern Oscillation (ENSO) are independent climate modes, which frequently co-occur, driving significant interannual changes within the Indian Ocean. We use a four-decade hindcast from a coupled biophysical ocean general circulation model, to disentangle patterns of chlorophyll anomalies driven by these two climate modes. Comparisons with remotely sensed records show that the simulation competently reproduces the chlorophyll seasonal cycle, as well as open-ocean anomalies during the 1997/1998 ENSO and IOD event. Results suggest that anomalous surface and euphotic-layer chlorophyll blooms in the eastern equatorial Indian Ocean in fall, and southern Bay of Bengal in winter, are primarily related to IOD forcing. A negative influence of IOD on chlorophyll concentrations is shown in a region around the southern tip of India in fall. IOD also depresses depth-integrated chlorophyll in the 5–10° S thermocline ridge region, yet the signal is negligible in surface chlorophyll. The only investigated region where ENSO has a greater influence on chlorophyll than does IOD, is in the Somalia upwelling region, where it causes a decrease in fall and winter chlorophyll by reducing local upwelling winds. Yet unlike most other regions examined, the combined explanatory power of IOD and ENSO in predicting depth-integrated chlorophyll anomalies is relatively low in this region, suggestive that other drivers are important there. We show that the chlorophyll impact of climate indices is frequently asymmetric, with a general tendency for larger positive than negative chlorophyll anomalies. Our results suggest that ENSO and IOD cause significant and predictable regional re-organisation of chlorophyll via their influence on near-surface oceanography. Resolving the details of these effects should improve our understanding, and eventually gain predictability, of interannual changes in Indian Ocean productivity, fisheries, ecosystems and carbon budgets.

scholarly journals Investigation of weather anomalies in the low-latitude islands of the Indian Ocean in 1991

2015 ◽  
Vol 33 (7) ◽  
pp. 789-804 ◽  
Author(s):  
A. Réchou ◽  
S. Kirkwood
Keyword(s):  
Indian Ocean ◽  
El Niño ◽  
Volcanic Eruption ◽  
El Nino ◽  
Sunshine Duration ◽  
Global Precipitation Climatology Project ◽  
The Philippines ◽  
Quasi Biennial Oscillation ◽  
Mount Pinatubo ◽  
The Indian Ocean

Abstract. Temperature, precipitation and sunshine duration measurements at meteorological stations across the southern Indian Ocean have been analysed to try to differentiate the possible influence of the Mount Pinatubo volcanic eruption in the Philippines in June 1991 and the normal weather forcings. During December 1991, precipitation on the tropical islands Glorieuses (11.6° S) and Mayotte (12.8° S) was 4 and 3 times greater, respectively, than the climatological mean (precipitation is greater by more than than twice the standard deviation (SD)). Mean sunshine duration (expressed in sun hours per day) was only 6 h on Mayotte, although the sunshine duration is usually more than 7.5 ± 0.75 h, and on the Glorieuses it was only 5 h, although it is usually 8.5 ± 1 h. Mean and SD of sunshine duration are based on December (1964–2001 for Mayotte, 1966–1999 for the Glorieuses). The Madden–Julian Oscillation (MJO) is shown to correlate best with precipitation in this area. Variability controlling the warm zone on these two islands can be increased by the Indian Ocean Dipole (IOD), El Niño, the quasi-biennial oscillation (QBO) and/or solar activity (sunspot number, SSN). However, temperature records of these two islands show weak dependence on such forcings (temperatures are close to the climatological mean for December). This suggests that such weather forcings have an indirect effect on the precipitation. December 1991 was associated with unusually low values of the MJO index, which favours high rainfall, as well as with El Niño, eastern QBO and high SSN, which favour high variability. It is therefore not clear whether the Mount Pinatubo volcanic eruption had an effect. Since the precipitation anomalies at the Glorieuses and Mayotte are more or less local (Global Precipitation Climatology Project (GPCP) data) and the effect of the Pinatubo volcanic cloud should be more widespread, it seems unlikely that Pinatubo was the cause. Islands at higher southern latitudes (south of Tromelin at 15.5° S) were not affected by the Pinatubo eruption in terms of sunshine duration, precipitation or temperature.

scholarly journals Interaction between El Niño and Extreme Indian Ocean Dipole

2010 ◽  
Vol 23 (3) ◽  
pp. 726-742 ◽  
Author(s):  
Jing-Jia Luo ◽  
Ruochao Zhang ◽  
Swadhin K. Behera ◽  
Yukio Masumoto ◽  
Fei-Fei Jin ◽  
...  
Keyword(s):  
Indian Ocean ◽  
El Niño ◽  
Indian Ocean Dipole ◽  
El Nino ◽  
Walker Circulation ◽  
Global Ocean ◽  
Tropical Ocean ◽  
The Indian Ocean ◽  
Major Attention ◽  
The Individual

Abstract Climate variability in the tropical Indo-Pacific sector has undergone dramatic changes under global ocean warming. Extreme Indian Ocean dipole (IOD) events occurred repeatedly in recent decades with an unprecedented series of three consecutive episodes during 2006–08, causing vast climate and socioeconomic effects worldwide and weakening the historic El Niño–Indian monsoon relationship. Major attention has been paid to the El Niño influence on the Indian Ocean, but how the IOD influences El Niño and its predictability remained an important issue to be understood. On the basis of various forecast experiments activating and suppressing air–sea coupling in the individual tropical ocean basins using a state-of-the-art coupled ocean–atmosphere model with demonstrated predictive capability, the present study shows that the extreme IOD plays a key role in driving the 1994 pseudo–El Niño, in contrast with traditional El Niño theory. The pseudo–El Niño is more frequently observed in recent decades, coincident with a weakened atmospheric Walker circulation in response to anthropogenic forcing. The study’s results suggest that extreme IOD may significantly enhance El Niño and its onset forecast, which has being a long-standing challenge, and El Niño in turn enhances IOD and its long-range predictability. The intrinsic El Niño–IOD interaction found here provides hope for enhanced prediction skill of both of these climate modes, and it sheds new light on the tropical climate variations and their changes under the influence of global warming.

scholarly journals Impacts of El Niño 2015 and the Indian Ocean Dipole 2016 on Rainfall in the Pameungpeuk and Cilacap Regions

2017 ◽  
Vol 31 (2) ◽  
pp. 184-195 ◽  
Author(s):  
Martono Martono ◽  
Teguh Wardoyo
Keyword(s):  
Indian Ocean ◽  
El Niño ◽  
Indian Ocean Dipole ◽  
El Nino ◽  
Descriptive Analysis ◽  
Daily Rainfall ◽  
Surface Current ◽  
Sea Surface ◽  
The Indian Ocean ◽  
Rainfall Anomalies

El Niño and the Indian Ocean Dipole (IOD) are oceanographic phenomena which occur in the tropical Pacific Ocean and the Indian Ocean due to air–sea interactions. These phenomena affect climate variability both regionally and globally. This study was conducted to understand the impacts of El Niño 2015 and IOD 2016 events on rainfall in the Pameungpeuk and Cilacap regions. The data used consists of the NIÑO3.4 index, IOD index, daily rainfall from 1987–2016, daily sea surface temperature from 1987–2016, daily sea surface height from 1994–2016 and pentad sea surface current from 2007–2016. The method used in this research was a descriptive analysis. The results have shown that rainfall in Pameungpeuk and Cilacap was influenced by El Niño 2015 and negative IOD 2016. During El Niño 2015 a decrease in rainfall occurred, whereas during negative IOD 2016 rainfall increased. Rainfall anomalies in the east season and the second transition season during El Niño 2015 in Pameungpeuk reached −107 mm and −374 mm; meanwhile in Cilacap rainfall anomalies reached −111 mm and −218 mm. Conversely, rainfall anomalies during negative IOD 2016 reached 109 mm and 360 mm in Pameungpeuk, and in Cilacap reached 293 mm and 365 mm. Changes in rainfall in Pameungpeuk and Cilacap during El Niño 2015 and negative IOD 2016 events were closely related to the weakening and strengthening of convections in the southern waters of Java.

scholarly journals Seasonal climate summary for the southern hemisphere (winter 2016): a strong negative Indian Ocean Dipole brings wet conditions to Australia

2018 ◽  
Vol 68 (1) ◽  
pp. 101
Author(s):  
Blair Trewin
Keyword(s):  
Indian Ocean ◽  
Southern Hemisphere ◽  
El Niño ◽  
Indian Ocean Dipole ◽  
El Nino ◽  
Atmospheric Circulation Patterns ◽  
Circulation Patterns ◽  
The Indian Ocean ◽  
Hemisphere Winter ◽  
Neutral Conditions

This is a summary of the southern hemisphere atmospheric circulation patterns and meteorological indices for winter 2016; an account of seasonal rainfall and temperature for the Australian region and the broader southern hemisphere is also provided. One of the strongest negative phases on record of the Indian Ocean Dipole (IOD) developed during the season, contributing to Australia's second wettest winter on record, with rainfall above average over the vast majority of the continent. Neutral conditions prevailed in the tropical Pacific following the end of a strong El Niño event in autumn 2016, but the continuing effect of the 2015-16 El Niño was still evident in southern hemisphere temperatures, which were at or near record high levels.

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