Oscillatory Climate Modes in the Indian Monsoon, North Atlantic, and Tropical Pacific

• Published in: Journal of Climate
• Main Authors: Feliks, Yizhak, Groth, Andreas, Ghil, Michael, Robertson, Andrew W.
• Other Authors: Department of Atmospheric and Oceanic Sciences Los Angeles (AOS), University of California Los Angeles (UCLA), University of California-University of California, Institute of Geophysics and Planetary Physics Los Angeles (IGPP), CNRS, Dept Geosci, Paris, France, Laboratoire de Météorologie Dynamique (UMR 8539) (LMD), Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École des Ponts ParisTech (ENPC)-École polytechnique (X)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), Columbia Univ, Int Res Inst Climate & Soc, Palisades, NY USA
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2013
• Subjects: [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology; Indian; Pacific; North Atlantic
• Online Access: https://hal.archives-ouvertes.fr/hal-01099078; https://hal.archives-ouvertes.fr/hal-01099078/document; https://hal.archives-ouvertes.fr/hal-01099078/file/%5B15200442%20-%20Journal%20of%20Climate%5D%20Oscillatory%20Climate%20Modes%20in%20the%20Indian%20Monsoon,%20North%20Atlantic,%20and%20Tropical%20Pacific.pdf; https://doi.org/10.1175/JCLI-D-13-00105.1

International audience This paper explores the three-way interactions between the Indian monsoon, the North Atlantic, and the tropical Pacific. Four climate records were analyzed: the monsoon rainfall in two Indian regions, the Southern Oscillation index for the tropical Pacific, and the NAO index for the North Atlantic. The individual records exhibit highly significant oscillatory modes with spectral peaks at 7-8 yr and in the quasi-biennial and quasi-quadrennial bands.The interactions between the three regions were investigated in the light of the synchronization theory of chaotic oscillators. The theory was applied here by combining multichannel singular-spectrum analysis (M-SSA) with a recently introduced varimax rotation of the M-SSA eigenvectors.A key result is that the 7-8-yr and 2.7-yr oscillatory modes in all three regions are synchronized, at least in part. The energy-ratio analysis, as well as time-lag results, suggests that the NAO plays a leading role in the 7-8-yr mode. It was found therewith that the South Asian monsoon is not slaved to forcing from the equatorial Pacific, although it does interact strongly with it. The time-lag analysis pinpointed this to be the case in particular for the quasi-biennial oscillatory modes.Overall, these results confirm that the approach of synchronized oscillators, combined with varimax-rotated M-SSA, is a powerful tool in studying teleconnections between regional climate modes and that it helps identify the mechanisms that operate in various frequency bands. This approach should be readily applicable to ocean modes of variability and to the problems of air-sea interaction as well.