Differential Influences of Teleconnections from the Indian and Pacific Oceans on Rainfall Variability in Southeast Asia

Abdul Azim Amirudin,Fredolin Tangang,Ester Salimun,Liew Juneng,Muhamad Zuhairi

doi:10.3390/atmos11090886

Abdul Azim Amirudin, Fredolin Tangang + Show 3 more

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https://doi.org/10.3390/atmos11090886

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Journal: Atmosphere	Publication Date: Aug 21, 2020
Citations: 23	License type: CC BY 4.0

Affiliation: National University of Malaysia

Abstract

This study investigates the individual and combined impacts of El Niño and the positive Indian Ocean Dipole (IOD) on the Southeast Asia (SEA) rainfall variability. Using composite and partial correlation techniques, it is shown that both inter-annual events have individually distinct impacts on the SEA rainfall anomaly distribution. The results showed that the impacts of the co-occurrence of El Niño and IOD events are significant compared to the individual effects of pure El Niño or pure IOD. During June-July-August and September-October-November, the individual impacts of the pure El Niño and IOD events are similar but less significant. Both events caused negative impacts over the southern part of SEA during June-July-August (JJA) and propagated northeastward/eastward during September-October-November (SON). Thus, there are significant negative impacts over the southern part of SEA during the co-occurrence of both events. The differential impacts on the anomalous rainfall patterns are due to the changes in the sea surface temperature (SST) surrounding the region. Additionally, the differences are also related to the anomalous regional atmospheric circulations that interact with the regional SST. The anomalous Walker circulation that connects the Indian Ocean and tropical Pacific Ocean also plays a significant role in determining the regional anomalous rainfall patterns.

Highlights

Southeast Asia (SEA) lies in between two major oceans, the Pacific and the Indian Ocean, which both play an important role in the world’s climate variability
The Dipole Mode Index (DMI) is defined based on Saji and Yamagata [13], in which the strength is represented by the anomalous sea surface temperature (SST) differences between the tropical western Indian Ocean (50◦ E–70◦ E, 10◦ S–10◦ N) and the tropical south-eastern
During the co-occurrence of the El Niño and Indian Ocean Dipole (IOD) events, the rainfall anomaly distributions and northeastward evolutions were shown to resemble the analysis of Juneng and Tangang [4]

Summary

Introduction

Southeast Asia (SEA) lies in between two major oceans, the Pacific and the Indian Ocean, which both play an important role in the world’s climate variability. Phenomenon have been studied due to their great socio-economic and community impacts [1,2,3,4,5,6,7,8]. This applies to the large-scale inter-annual phenomenon which originates from the tropical Indian. The impacts of the IOD are not limited to the equatorial Indian Ocean, but appear globally through changes in atmospheric circulation [13]. Despite the potential impact on the regional climate in SEA, previous studies of the impacts of the IOD over this region are rather limited [10,13,14,15]

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