ORIGINAL PAPER Recent changes in the prominent modes of Indian Ocean dipole in response to the tropical Pacific Ocean SST patterns Prasanth A Pillai 1 & Ravikumar C. Nair 2 & C. V Vidhya 3 Received: 4 January 2019 /Accepted: 16 April 2019 # Springer-Verlag GmbH Austria, part of Springer Nature 2019 Abstract The present study examines the prominent patterns of Indian Ocean dipole (IOD) associated with the recent changes in the Pacific Ocean variability centered around 1998. EOF analysis of boreal fall (September through November (SON)) Indian Ocean sea surface temperature anomaly (SSTA) reveals that EOF1 (32% variability) is dominated by East Pacific El Niño-IOD co-occurring pattern during 1980–1998 (period 1). During period 2 (1999–2016), central Pacific El Niño also influence EOF1 (26% variabil- ity) and the IOD co-occurrence is reduced. EOF2 with 22% variability has central Indian Ocean dipole pattern co-occurred with El Niño Modoki during period 1, and it became basin-wide south-north dipole pattern in period 2 with reduced (20%) variability. At the same time, local Indian Ocean variability induced by SST anomalies centered on western side of Australia (Ningaloo Niño/ Niña) is found to be related to EOF2 in both the periods and its influence is stronger after 1998, when its association with El Niño weakens. Third mode is ENSO independent IOD pattern in both the epochs and has more variability in period 2. Thus, during period 1, both East Pacific and central Pacific El Niño events are well separated as major two modes of tropical Pacific Ocean. These two flavors are associated with two different IOD patterns. But in the second period, first mode of Pacific Ocean is strongly related to both the El Niño flavors and reduced the co-occurrence of IOD with the El Niño modes and the effect of local Indian Ocean processes in the IO variability is intensified. 1 Introduction Indian Ocean dipole (IOD) mode (Saji et al. 1999; Webster et al. 1999) is the major climate phenomenon in the tropical Indian Ocean. It is represented by positive sea surface temper- ature (SST) anomaly in the western and negative SST anom- aly (SSTA) in the eastern Indian Ocean during its positive phase and vice versa for negative phase. IOD has large impact on the climate of the surrounding and remote regions such as East Asia, India, Australia, Europe, and South America (Ashok et al. 2001; Guan and Yamagata 2003; Saji and Yamagata 2003; Yamagata et al. 2004). Thus, understanding the variability of IOD in different time scales are crucial for the global climate studies. Even though IOD is the result of air-sea interaction over Indian Ocean (Ashok et al. 2001; Allan et al. 2001), majority of the positive IOD events co- occurred with El Niño and a few negative IOD events are associated with La Niña phenomenon in the Pacific. Thus, the independency of IOD with regard to El Niño Southern Oscillation (ENSO) is still not clear and it leads to contrasting results (Allan et al. 2001; Ashok et al. 2001; 2004; Pillai and Mohankumar 2010; etc.). Meanwhile, both ENSO and IOD phenomena have strong decadal variability in frequency, intensity, and propagation pattern (An and Wang 2000; Timmermann 2003; An and Jin 2004; etc. for ENSO and Ashok et al. 2001; Lee and McPhaden 2008; Han et al. 2014; Feng et al. 2010; Li and Han 2015; etc for IOD). The decadal ENSO variability was explained either as internal mode of coupled ocean- atmosphere system in the tropical Pacific (Kirtmann and Schopf 1998; Timmermann and Jin 2002; Timmermann 2003) or excited by stochastic forcing (Newman et al. 2003). These decadal variabilities of ENSO resulted in different flavors of ENSO in which the central Pacific ENSO (ENSO Modoki; Ashok et al. 2007) is stronger in the recent periods. * Prasanth A Pillai prasanth@tropmet.res.in 1 Monsoon Mission Program, Indian Institute of Tropical Meteorology, Dr. HomiBhaba Road, Pashan, Pune 411008, India 2 CSIR-National Institute of Oceanography, Regional Centre, Kochi, India 3 School of Ocean Studies and Technology, Kerala University of Fisheries and Ocean Studies, Kochi, India Theoretical and Applied Climatology https://doi.org/10.1007/s00704-019-02875-z