| Decadal and Interannual Variability of the Indian Ocean Dipole |
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| 作者姓名： | 袁媛 陈仲良 周文 李崇银 |
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| 作者单位： | State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics，Institute of Atmospheric Physics，Chinese Academy of Sciences，CityU-IAP Laboratory for Atmospheric Sciences，City University of Hong Kong |
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| 基金项目： | 国家自然科学基金，中国科学院资助项目，City University of Hong Kong and the Institute of Atmo-spheric Physics |
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| 摘 要： | This study investigates the decadal and interannual variability of the Indian Ocean Dipole （IOD）. It is found that the long-term IOD index displays a decadal phase variation. Prior to 1920 negative phase dominates but after 1960 positive phase prevails. Under the warming background of the tropical ocean, a larger warming trend in the western Indian Ocean is responsible for the decadal phase variation of the IOD mode. Due to reduced latent heat loss from the local ocean, the western Indian Ocean warming may be caused by the weakened Indian Ocean westerly summer monsoon. The interannual air-sea coupled IOD mode varies on the background of its decadal variability. During the earlier period （1948-1969）, IOD events are characterized by opposing SST anomaly （SSTA） in the western and eastern Indian Ocean, with a single vertical circulation above the equatorial Indian Ocean. But in the later period （1980-2003）, with positive IOD dominating, most IOD events have a zonal gradient perturbation on a uniform positive SSTA. However, there are three exceptionally strong positive IOD events （1982, 1994, and 1997）, with opposite SSTA in the western and eastern Indian Ocean, accompanied by an El Nifio event. Consequently, two anomalous reversed Walker cells are located separately over the Indian Ocean and western-eastern Pacific; the one over the Indian Ocean is much stronger than that during other positive IOD events.
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| 关 键 词： | 印度洋 偶极 十相位变更 变异性 |
| 收稿时间： | 12 June 2007 |
Decadal and interannual variability of the Indian Ocean Dipole |
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| Yuan?Yuan,C.?L.?Johnny?Chan,Wen?Zhou,Chongyin?Li.Decadal and Interannual Variability of the Indian Ocean Dipole[J].Advances in Atmospheric Sciences,2008,25(5):856-866. |
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| Authors: | Yuan Yuan C L Johnny Chan Wen Zhou Chongyin Li |
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| Affiliation: | [1]State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029 [2]CityU-IAP Laboratory for Atmospheric Sciences, City University of Hong Kong, Hong Kong [3]Graduate University of Chinese Academy of Sciences, Beijing 100049 [4]Department of Physics and Materials Science, City University of Hong Kong, Hong Kong |
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| Abstract: | This study investigates the decadal and interannual variability of the Indian Ocean Dipole(IOD).It is found that the long.term IOD index displays a decadal phase variation.Prior to 1920 negative phase dominates.but after 1960 positive phase prevails.Under the warming background of the tropical ocean,a larger warming trend in the western Indian Ocean is responsible for the decadal phase variation of the IOD mode.Due to reduced latent heat lOSS from the local ocean.the western Indian Ocean warming may be caused by the weakened Indian Ocean westerly summer monsoon. The interannual air-sea coupled IOD mode varies on the background of its decadal variability.During the earlier period(1948-1969),IOD events are characterized by opposing SST anomaly(ssTA)in the western and eastern Indian Ocean.with a single vertical circulation above the equatorial Indian Ocean. But in the later period (1980-2003),with positive IOD dominating,most IOD events have a zonal gradient perturbation on a uniform positive SSTA.However.there are three exceptionally strong positive IOD events (1982,1994,and 1997),with opposite ssTA in the western and eastern Indian Ocean,accompanied by an El Ni(n)o event.Consequently,two anomalous reversed Walker cells are located separately over the Indian Ocean and western.eastern Pacific;the one over the Indian Ocean iS much stronger than that during other positive IOD events. |
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| Keywords: | Indian Ocean dipole ENSO decadal phase variation interannual variability |
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