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GEOPHYSICAL RESEARCH LETTERS, VOL. 34, L09706, doi:10.1029/2007GL029528, 2007

Multidecadal variability in the transmission of ENSO signals to the Indian Ocean

G. Shi

Department of Biological and Physical Sciences, University of Southern Queensland, Toowoomba, Queensland, Australia


J. Ribbe

Department of Biological and Physical Sciences, University of Southern Queensland, Toowoomba, Queensland, Australia


W. Cai

Marine and Atmospheric Research, Commonwealth Scientific and Industrial Research Organisation, Aspendale, Victoria, Australia


T. Cowan

Wealth from Oceans Flagship, Commonwealth Scientific and Industrial Research Organisation, Cleveland, Queensland, Australia


Abstract

Since 1980, transmission of El Niño-Southern Oscillation (ENSO) signals into the Indian Ocean involves an equatorial, and a subtropical North Pacific (NP) Rossby wave pathway. We examine the robustness of the amount of energy that leaves the Pacific via each of the pathway using the Simple Ocean Data Assimilation with the Parallel Ocean Program (SODA-POP) reanalysis and a multi-century coupled model control experiment. We find that in the pre-1980 period, little ENSO signal is transmitted to the Indian Ocean and does not involve the subtropical NP pathway. Such multidecadal variability is periodically produced by the climate model. Examinations reveal that when ENSO is weak as determined by Niño3.4, their meridional extent is narrow, the associated discharge-recharge does not involve the subtropical NP pathway; further, weak ENSO events have a low signal-to-noise ratio, making the transmission hard to detect. The dynamics of multidecadal variability in ENSO strength awaits further investigation.

Received 18 February 2007; accepted 10 April 2007; published 11 May 2007.

Keywords: Indo-Pacific transmission; decadal change; oceanic teleconnection.

Index Terms: 1616 Global Change: Climate variability (1635, 3305, 3309, 4215, 4513); 1620 Global Change: Climate dynamics (0429, 3309); 3305 Atmospheric Processes: Climate change and variability (1616, 1635, 3309, 4215, 4513); 4215 Oceanography: General: Climate and interannual variability (1616, 1635, 3305, 3309, 4513); 4513 Oceanography: Physical: Decadal ocean variability (1616, 1635, 3305, 4215).

Read Full Article (file size: 2722862 bytes)    Cited by

Citation: Shi, G., J. Ribbe, W. Cai, and T. Cowan (2007), Multidecadal variability in the transmission of ENSO signals to the Indian Ocean, Geophys. Res. Lett., 34, L09706, doi:10.1029/2007GL029528.