Influence of the strongest positive Indian Ocean Dipole and an El Niño Modoki event on the 2019 Indian summer monsoon

2021 ◽  
pp. 101235
Author(s):  
Syam Sankar ◽  
P. Vijaykumar ◽  
S. Abhilash ◽  
K. Mohanakumar
Keyword(s):  
Indian Ocean ◽  
Summer Monsoon ◽  
Indian Summer Monsoon ◽  
El Niño ◽  
Indian Ocean Dipole ◽  
El Nino ◽  
El Niño Modoki ◽  
Positive Indian Ocean Dipole

scholarly journals Two-year consecutive concurrences of positive Indian Ocean Dipole and Central Pacific El Niño preconditioned the 2019/2020 Australian “black summer” bushfires

2020 ◽  
Vol 7 (1) ◽  
Author(s):  
Guojian Wang ◽  
Wenju Cai
Keyword(s):  
Indian Ocean ◽  
El Niño ◽  
Indian Ocean Dipole ◽  
El Nino ◽  
Greenhouse Warming ◽  
Central Pacific ◽  
Central Pacific El Niño ◽  
Positive Indian Ocean Dipole ◽  
The Future ◽  
Rainfall Anomalies

Abstract The 2019/20 Australian black summer bushfires were particularly severe in many respects, including its early commencement, large spatial coverage, and large number of burning days, preceded by record dry and hot anomalies. Determining whether greenhouse warming has played a role is an important issue. Here, we examine known modes of tropical climate variability that contribute to droughts in Australia to provide a gauge. We find that a two-year consecutive concurrence of the 2018 and 2019 positive Indian Ocean Dipole and the 2018 and 2019 Central Pacific El Niño, with the former affecting Southeast Australia, and the latter influencing eastern and northeastern Australia, may explain many characteristics of the fires. Such consecutive events occurred only once in the observations since 1911. Using two generations of state-of-the-art climate models under historical and a business-as-usual emission scenario, we show that the frequency of such consecutive concurrences increases slightly, but rainfall anomalies during such events are stronger in the future climate, and there are drying trends across Australia. The impact of the stronger rainfall anomalies during such events under drying trends is likely to be exacerbated by greenhouse warming-induced rise in temperatures, making such events in the future even more extreme.

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 How Does El Niño Affect Predictability Barrier of Its Accompanied Positive Indian Ocean Dipole Event?

2021 ◽  
Vol 9 (11) ◽  
pp. 1169
Author(s):  
Da Liu ◽  
Wansuo Duan ◽  
Rong Feng
Keyword(s):  
Heat Flux ◽  
Indian Ocean ◽  
Latent Heat Flux ◽  
El Niño ◽  
Indian Ocean Dipole ◽  
El Nino ◽  
Sea Temperature ◽  
Positive Indian Ocean Dipole ◽  
Initial Errors ◽  
Temperature Errors

The effects of El Niño on the predictability of positive Indian Ocean dipole (pIOD) events are investigated by using the GFDL CM2p1 coupled model from the perspective of error growth. The results show that, under the influence of El Niño, the summer predictability barrier (SPB) for pIOD tends to intensify and the winter predictability barrier (WPB) is weakened. Since the reason for the weakening of WPB has been explained in a previous study, the present study attempts to explore why the SPB is enhanced. The results demonstrate that the initial sea temperature errors, which are most likely to induce SPB for pIOD with El Niño, possess patterns similar to those for pIOD without El Niño, whose dominant errors concentrate in the tropical Pacific Ocean (PO), with a pattern of negative SST errors occurring in the eastern and central PO and subsurface sea temperature errors being negative in the eastern PO and positive in the western PO. By tracking the development of such initial errors, it is found that the initial errors over PO lead to anomalous westerlies in the southeastern Indian Ocean (IO) through the effect of double-cell Walker circulation. Such westerly anomalies are inhibited by the strongest climatological easterly wind and the southeasterlies related to the pIOD event itself in summer, while they are enhanced by El Niño. This competing effect causes the intensified seasonal variation in latent heat flux, with much less loss in summer under the effect of El Niño. The greater suppression of the loss of latent heat flux favors the positive sea surface temperature (SST) errors developing much faster in the eastern Indian Ocean in summer, and eventually induces an enhanced SPB for pIOD due to El Niño.

scholarly journals Further Insights on the Influence of the Indian Ocean Dipole on the Following Year’s ENSO from Observations and CMIP5 Models

2016 ◽  
Vol 29 (2) ◽  
pp. 637-658 ◽  
Author(s):  
Nicolas C. Jourdain ◽  
Matthieu Lengaigne ◽  
Jérome Vialard ◽  
Takeshi Izumo ◽  
Alexander Sen Gupta
Keyword(s):  
Indian Ocean ◽  
El Niño ◽  
Indian Ocean Dipole ◽  
Linear Prediction ◽  
El Nino ◽  
Southern Oscillation ◽  
Cmip5 Models ◽  
Water Volume ◽  
Positive Indian Ocean Dipole ◽  
One Year

Abstract Recent observational studies have suggested that negative and positive Indian Ocean dipole (IOD) events (nIOD and pIOD, respectively) favor a transition toward, respectively, El Niño and La Niña events one year later. These statistical inferences are however limited by the length and uncertainties in the observational records. This paper compares observational datasets with twenty-one 155-yr historical simulations from phase 5 of CMIP (CMIP5) to assess IOD and El Niño–Southern Oscillation (ENSO) properties along with their synchronous and delayed relationships. In the observations and most CMIP5 models, it is shown that El Niños tend to be followed by La Niñas but not the opposite, that pIODs co-occur more frequently with El Niños than nIODs with La Niñas, that nIODs tend to be followed by El Niños one year later less frequently than pIODs by La Niñas, and that including an IOD index in a linear prediction based on the Pacific warm water volume improves ENSO peak hindcasts at 14 months lead. The IOD–ENSO delayed relationship partly results from a combination of ENSO intrinsic properties (e.g., the tendency for El Niños to be followed by La Niñas) and from the synchronous IOD–ENSO relationship. The results, however, reveal that this is not sufficient to explain the high prevalence of pIOD–Niña transitions in the observations and 75% of the CMIP5 models, and of nIOD–Niño transitions in 60% of CMIP5 models. This suggests that the tendency of IOD to lead ENSO by one year should be explained by a physical mechanism that, however, remains elusive in the CMIP5 models. The ability of many CMIP5 models to reproduce the delayed influence of the IOD on ENSO is nonetheless a strong incentive to explore extended-range dynamical forecasts of ENSO.

scholarly journals Regional and Local Impacts of the ENSO and IOD Events of 2015 and 2016 on the Indian Summer Monsoon—A Bhutan Case Study

Atmosphere ◽  
2021 ◽  
Vol 12 (8) ◽  
pp. 954
Author(s):  
Katherine Power ◽  
Josefine Axelsson ◽  
Norbu Wangdi ◽  
Qiong Zhang
Keyword(s):  
Indian Ocean ◽  
Summer Monsoon ◽  
Indian Summer Monsoon ◽  
El Niño ◽  
Late Onset ◽  
El Nino ◽  
Southern Oscillation ◽  
Regional Scale ◽  
Local Scale ◽  
The Indian Ocean

The Indian Summer Monsoon (ISM) plays a vital role in the livelihoods and economy of those living on the Indian subcontinent, including the small, mountainous country of Bhutan. The ISM fluctuates over varying temporal scales and its variability is related to many internal and external factors including the El Niño Southern Oscillation (ENSO) and the Indian Ocean Dipole (IOD). In 2015, a Super El Niño occurred in the tropical Pacific alongside a positive IOD in the Indian Ocean and was followed in 2016 by a simultaneous La Niña and negative IOD. These events had worldwide repercussions. However, it is unclear how the ISM was affected during this time, both at a regional scale over the whole ISM area and at a local scale over Bhutan. First, an evaluation of data products comparing ERA5 reanalysis, TRMM and GPM satellite, and GPCC precipitation products against weather station measurements from Bhutan, indicated that ERA5 reanalysis was suitable to investigate ISM change in these two years. The reanalysis datasets showed that there was disruption to the ISM during this period, with a late onset of the monsoon in 2015, a shifted monsoon flow in July 2015 and in August 2016, and a late withdrawal in 2016. However, this resulted in neither a monsoon surplus nor a deficit across both years but instead large spatial-temporal variability. It is possible to attribute some of the regional scale changes to the ENSO and IOD events, but the expected impact of a simultaneous ENSO and IOD events are not recognizable. It is likely that 2015/16 monsoon disruption was driven by a combination of factors alongside ENSO and the IOD, including varying boundary conditions, the Pacific Decadal Oscillation, the Atlantic Multi-decadal Oscillation, and more. At a local scale, the intricate topography and orographic processes ongoing within Bhutan further amplified or dampened the already altered ISM.

scholarly journals The Indian Ocean Dipole: A Missing Link between El Niño Modokiand Tropical Cyclone Intensity in the North Indian Ocean

Climate ◽  
2019 ◽  
Vol 7 (3) ◽  
pp. 38 ◽  
Author(s):  
Kopal Arora ◽  
Prasanjit Dash
Keyword(s):  
Tropical Cyclone ◽  
Indian Ocean ◽  
El Niño ◽  
Indian Ocean Dipole ◽  
El Nino ◽  
North Indian Ocean ◽  
Missing Link ◽  
El Niño Modoki ◽  
The North ◽  
The Indian Ocean

This study is set out to understand the impact of El Niño Modoki and the Tropical Cyclone Potential Intensity (TCPI) in the North Indian Ocean. We also hypothesized and tested if the Indian Ocean Dipole (IOD) reveals a likely connection between the two phenomena. An advanced mathematical tool namely the Empirical Mode Decomposition (EMD) is employed for the analysis. A major advantage of using EMD is its adaptability approach to deal with the non-linear and non-stationary signals which are similar to the signals used in this study and are also common in both atmospheric and oceanic sciences. This study has identified IOD as a likely missing link to explain the connection between El Niño Modoki and TCPI. This lays the groundwork for future research into this connection and its possible applications in meteorology.

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