Abstract
Abstract. The Pacific–Indian Ocean associated mode (PIOAM), defined as the first dominant mode (empirical orthogonal function, EOF1) of sea surface temperature anomalies (SSTAs) in the Pacific–Indian Ocean between 20∘ S and 20∘ N, is the product of the tropical air–sea interaction at the cross-basin scale and the main mode of ocean variation in the tropics. Evaluating the capability of current climate models to simulate the PIOAM and finding the possible factors that affect the simulation results are beneficial in the pursuit of more accurate future climate change prediction. Based on the 55-year Hadley Centre Global Sea Ice and Sea Surface Temperature (HadISST) dataset and the output data from 21 Coupled Model Intercomparison Project (CMIP) phase 5 (CMIP5) models, the PIOAM in these CMIP5 models is assessed. Instead of using the time coefficient (PC1) of the PIOAM as its index, we chose to utilize the alternative PIOAM index (PIOAMI), defined with SSTA differences in the boxes, to describe the PIOAM. It is found that the explained variance of the PIOAM in almost all 21 CMIP5 models is underestimated. Although all models reproduce the spatial pattern of the positive sea surface temperature anomaly in the eastern equatorial Pacific well, only one-third of these models successfully simulate the El Niño–Southern Oscillation (ENSO) mode with the east–west inverse phase in the Pacific Ocean. In general, CCSM4, GFDL-ESM2M and CMCC-CMS have a stronger capability to capture the PIOAM than the other models. The strengths of the PIOAM in the positive phase in less than one-fifth of the models are slightly greater, and very close to the HadISST dataset, especially CCSM4. The interannual variation of the PIOAM can be measured by CCSM4, GISS-E2-R and FGOALS-s2.
Highlights
As early as the 1960s, Bjerknes (1966, 1969) studied the phenomenon of El Niño–Southern Oscillation (ENSO)
Since the Pacific–Indian Ocean associated mode (PIOAM) is so important, how well do current climate models simulate it? To answer this question, the outputs from the climate system models for the Coupled Model Intercomparison Project (CMIP) phase 5 (CMIP5) were used for this research, from which we aim to provide a more complete evaluation of the PIOAM and try to find possible causes of the simulation biases
The sea surface temperature (SST) anomalies in the northwest Indian Ocean and the equatorial east-central Pacific Ocean is opposite to the SST anomalies in the western equatorial Pacific Ocean and the east Indian Ocean
Summary
As early as the 1960s, Bjerknes (1966, 1969) studied the phenomenon of El Niño–Southern Oscillation (ENSO). At the end of the 20th century, an interannual climate anomaly characterized by a sea surface temperature anomaly (SSTA) of opposing sign in the western and eastern tropical Indian Ocean, known as the Indian Ocean dipole (IOD), was reported by Saji et al (1999) and Webster et al (1999) and was catalogued as one of the major ocean–atmosphere coupled phenomena. The SSTA in the tropical Indian Ocean subsequently has been widely studied, and a great deal of literature has discussed the causes and mechanisms of the IOD, as well as its weather and climate impacts (Li and Mu, 2001; Li et al, 2003; Saji and Yamagata, 2003; Cai et al, 2005; Rao et al, 2007; Zheng et al, 2013; Wang and Wang, 2014).
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
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 callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
