Indian Ocean Dipole response to global warming: A multi-member study with CCSM4

TitleIndian Ocean Dipole response to global warming: A multi-member study with CCSM4
Publication TypeJournal Article
Year of Publication2013
AuthorsZhou ZQ, Xie SP, Zheng XT, Liu QY
JournalJournal of Ocean University of China
Date Published2013/06
Type of ArticleArticle
ISBN Number1672-5182
Accession NumberWOS:000318300200003
KeywordsCCSM4; circulation; enso; global; Indian Ocean Dipole (IOD); model; multi-member ensemble analysis; ocean-atmospheric interaction; pacific; variability; warming

Based on a coupled ocean-atmosphere model, the response of the Indian Ocean Dipole (IOD) mode to global warming is investigated with a six member ensemble of simulations for the period 1850-2100. The model can simulate the IOD features realistically, including the east-west dipole pattern and the phase locking in boreal autumn. The ensemble analysis suppresses internal variability and isolates the radiative forced response. In response to increasing greenhouse gases, a weakening of the Walker circulation leads to the easterly wind anomalies in the equatorial Indian Ocean and the shoaling thermocline in the eastern equatorial Indian Ocean (EEIO), and sea surface temperature and precipitation changes show an IOD-like pattern in the equatorial Indian Ocean. Although the thermocline feedback intensifies with shoaling, the interannual variability of the IOD mode surprisingly weakens under global warming. The zonal wind feedback of IOD is found to weaken as well, due to decreased precipitation in the EEIO. Therefore, the atmospheric feedback decreases much more than the oceanic feedback increases, causing the decreased IOD variance in this model.