Seasonality and Predictability of the Indian Ocean Dipole Mode: ENSO Forcing and Internal Variability
Publication in refereed journal

香港中文大學研究人員

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摘要This study evaluates the relative contributions to the Indian Ocean dipole (IOD) mode of interannual variability from the El Nino-Southern Oscillation (ENSO) forcing and ocean-atmosphere feedbacks internal to the Indian Ocean. The ENSO forcing and internal variability is extracted by conducting a 10-member coupled simulation for 1950-2012 where sea surface temperature (SST) is restored to the observed anomalies over the tropical Pacific but interactive with the atmosphere over the rest of the World Ocean. In these experiments, the ensemble mean is due to ENSO forcing and the intermember difference arises from internal variability of the climate system independent of ENSO. These elements contribute one-third and two-thirds of the total IOD variance, respectively. Both types of IOD variability develop into an east-west dipole pattern because of Bjerknes feedback and peak in September-November. The ENSO forced and internal IOD modes differ in several important ways. The forced IOD mode develops in August with a broad meridional pattern and eventually evolves into the Indian Ocean basin mode, while the internal IOD mode grows earlier in June, is more confined to the equator, and decays rapidly after October. The internal IOD mode is more skewed than the ENSO forced response. The destructive interference of ENSO forcing and internal variability can explain early terminating IOD events, referred to as IOD-like perturbations that fail to grow during boreal summer. The results have implications for predictability. Internal variability, as represented by preseason sea surface height anomalies off Sumatra, contributes to predictability considerably. Including this indicator of internal variability, together with ENSO, improves the predictability of IOD.
著者Yang Y, Xie SP, Wu LX, Kosaka Y, Lau NC, Vecchi GA
期刊名稱Journal of Climate
出版年份2015
月份10
日期1
卷號28
期次20
出版社AMER METEOROLOGICAL SOC
頁次8021 - 8036
國際標準期刊號0894-8755
電子國際標準期刊號1520-0442
語言英式英語
關鍵詞Atmosphere-ocean interaction; ENSO; Indian Ocean; Interannual variability
Web of Science 學科類別Meteorology & Atmospheric Sciences

上次更新時間 2021-17-01 於 00:58