JpGU-AGU Joint Meeting 2017

Presentation information

[EE] Poster

A (Atmospheric and Hydrospheric Sciences) » A-CG Complex & General

[A-CG44] [EE] Asian monsoon hydro-climate and water resources research for GEWEX

Sun. May 21, 2017 10:45 AM - 12:15 PM Poster Hall (International Exhibition Hall HALL7)

convener:Shinjiro Kanae(School of Environment and Society, Tokyo Institute of Technology), Atsushi Higuchi(Center for Environmental Remote Sensing (CEReS), Chiba University, Japan), Jun Matsumoto(Deaprtment of Geography, Tokyo Metropolitan University), Satoru Yokoi(Japan Agency for Marine-Earth Science and Technology)

[ACG44-P01] Dynamics of changing impacts of tropical Indo-Pacific variability on Indian and Australian rainfallDynamics of changing impacts of tropical Indo-Pacific variability on Indian and Australian rainfall

*Ziguang Li1, Xiaopei Lin1, wenju Cai2 (1.Ocean Univ. of China, 2.CSIRO)

Keywords:Monsoon, ENSO, IOD

A positive Indian Ocean Dipole (IOD) and a warm phase of the El Niño-Southern Oscillation (ENSO)
reduce rainfall over the Indian subcontinent and southern Australia. However, since the 1980s, El
Niño’s influence has been decreasing, accompanied by a strengthening in the IOD’s influence on
southern Australia but a reversal in the IOD’s influence on the Indian subcontinent. The dynamics are
not fully understood. Here we show that a post-1980 weakening in the ENSO-IOD coherence plays a
key role. During the pre-1980 high coherence, ENSO drives both the IOD and regional rainfall, and the
IOD’s influence cannot manifest itself. During the post-1980 weak coherence, a positive IOD leads to
increased Indian rainfall, offsetting the impact from El Niño. Likewise, the post-1980 weak ENSO-IOD
coherence means that El Niño’s pathway for influencing southern Australia cannot fully operate, and
as positive IOD becomes more independent and more frequent during this period, its influence on
southern Australia rainfall strengthens. There is no evidence to support that greenhouse warming plays
a part in these decadal fluctuations.