Abstract
The Indian Ocean sea surface temperature (SST) variability has been represented with the two dominant variability modes: the Indian Ocean basin-wide (IOBW) and dipole (IOD) modes. Here we investigate future changes of the two modes together with mean state and El Niño and Southern Oscillation (ENSO) relationship under the anthropogenic global warming using 20 coupled models that participated in the phase five of Coupled Model Intercomparison Project by comparing the historical run from 1950 to 2005 and the RCP 4.5 run from 2050 to 2099. The five best models are selected based on the evaluation of the 20 models’ performances in simulating the two modes and Indian Ocean basic state for the latest 56 years. They are capable of capturing the IOBW and IOD modes in their spatial distribution, seasonal cycle, major periodicity, and relationship with ENSO to some extent. The five best models project the significant changes in the Indian Ocean mean state and variability including the two dominant modes in the latter part of twenty-first century under the anthropogenic warming scenario. First, the annual mean climatological SST displays an IOD-like pattern change over the Indian Ocean with enhanced warming in the northwestern Indian Ocean and relatively weaker warming off the Sumatra–Java coast. It is also noted that the monthly SST variance is increased over the eastern and southwestern Indian Ocean. Second, the IOBW variability on a quasi-biennial time scale will be enhanced due to the strengthening of the ENSO–IOBW mode relationship although the total variance of the IOBW mode will be significantly reduced particularly during late summer and fall. The enhanced air-sea coupling over the Indian-western Pacific climate in response to El Nino activity in the future projection makes favorable condition for a positive IOD while it tends to derive relatively cold temperature over the eastern Indian Ocean. This positive IOD-like ENSO response weakens the relationship between the eastern Indian Ocean and El Nino while strengthens the relationship with western Indian Ocean. Third, the IOD mode, intrinsic coupled mode of the Indian Ocean may not be changed appreciably under the anthropogenic global warming.
Highlights
The Indian Ocean is a part of large warm water pool and neighboring the great monsoons of Asia that anchor the major convection center of the atmosphere (Saji et al 2006)
The five best models are selected based on the evaluation of the 20 models’ performances in simulating the two modes and Indian Ocean basic state for the latest 56 years. They are capable of capturing the Indian Ocean basin-wide (IOBW) and Indian Ocean dipole (IOD) modes in their spatial distribution, seasonal cycle, major periodicity, and relationship with El Nino and Southern Oscillation (ENSO) to some extent
This study investigates the future changes of the IOBW, and IOD modes projected by the 20 coupled atmosphere–ocean models (CGCMs) that participated in the CMIP5 by comparing two runs: the historical run under changing solar-volcanic forcing and anthropogenic influences from 1850 to 2005 and the Representative Concentration Pathway (RCP) 4.5 run assuming that radiative forcing will stabilize with an increases of about 4.5 Wm-2 after 2100 (Taylor et al 2012)
Summary
The Indian Ocean is a part of large warm water pool and neighboring the great monsoons of Asia that anchor the major convection center of the atmosphere (Saji et al 2006). Recent studies have found significant warming and changes in the Indian Ocean SST during recent few decades based on observation (Abram et al 2008; Alory et al 2007; Chowdary et al 2012; Ihara et al 2008). The Indian Ocean SST variability under global warming have explored through climate change projections (Du and Xie 2008; Meehl et al 2007a, b; Saji et al 2006; Vecchi and Soden 2007).
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
