On the Relationship Between Indian Ocean Dipole, Indian Summer Monsoon and ENSO

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EGU21-14562 https://doi.org/10.5194/egusphere-egu21-14562 EGU General Assembly 2021 © Author(s) 2021. This work is distributed under the Creative Commons Attribution 4.0 License.

On the relationship between Indian Ocean Dipole, Indian summer monsoon and ENSO

Annalisa Cherchi1, Pascal Terray2, Satyaban Bishoyi Ratna3, Virna Meccia1, and Sooraj K.P.4 1Institute of Atmospheric Sciences and Climate, National Research Council (ISAC-CNR), Bologna, Italy ([email protected]) 2LOCEAN/IPSL, Sorbonne Universités (UPMC, Univ Paris 06)-CNRS-IRD-MNHN, Paris, France 3Climatic Research Unit, School of Environmental Sciences, University of East Anglia, Norwich, NR4 7TJ, United Kingdom 4Centre for Climate Change Research, Indian Institute of Tropical Meteorology, Ministry of Earth Sciences (IITM-MoES), Pune 411008, India

The Indian Ocean Dipole (IOD) is one of the dominant modes of variability of the tropical Indian Ocean and it has been suggested to have a crucial role in the teleconnection between the Indian summer monsoon and El Nino Southern Oscillation (ENSO). The main ideas at the base of the influence of the IOD on the ENSO-monsoon teleconnection include the possibility that it may strengthen summer rainfall over India, as well as the opposite, and also that it may produce a remote forcing on ENSO itself. The Indian Ocean has been experiencing a warming, larger than any other basins, since the 1950s. During these decades, the summer monsoon rainfall over India decreased and the frequency of Indian Ocean Dipole (IOD) events increased. In the future the IOD is projected to further increase in frequency and amplitude with mean conditions mimicking the characteristics of its positive phase. Still, state of the art global climate models have large biases in representing IOD and monsoon mean state and variability, with potential consequences for properties and related teleconnections projected in the future. This works collects a review study of the influence of the IOD on the ISM and its relationship with ENSO, as well as new results on IOD projections comparing CMIP5 and CMIP6 models.