TROPICAL INDIAN OCEAN SUBSURFACE DIPOLE MODE AND DIAGNOSTIC ANALYSIS OF DIPOLE EVENT IN 1997/ 1998

Qian Haifeng; Yin Yonghong; Ni Yunqi

Vol.14, NO.2, 2003

Article Contents

Article Navigation > Journal of Applied Meteorological Science > 2003 > 14(2): 129-139

Qian Haifeng, Yin Yonghong, Ni Yunqi. Tropical Indian Ocean subsurface dipole mode and diagnostic analysis of dipole event in 1997/ 1998. J Appl Meteor Sci, 2003, 14(2): 129-139.

Citation:

Qian Haifeng, Yin Yonghong, Ni Yunqi. Tropical Indian Ocean subsurface dipole mode and diagnostic analysis of dipole event in 1997/ 1998. J Appl Meteor Sci, 2003, 14(2): 129-139.

Qian Haifeng, Yin Yonghong, Ni Yunqi. Tropical Indian Ocean subsurface dipole mode and diagnostic analysis of dipole event in 1997/ 1998. J Appl Meteor Sci, 2003, 14(2): 129-139.

Citation:

Qian Haifeng, Yin Yonghong, Ni Yunqi. Tropical Indian Ocean subsurface dipole mode and diagnostic analysis of dipole event in 1997/ 1998. J Appl Meteor Sci, 2003, 14(2): 129-139.

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TROPICAL INDIAN OCEAN SUBSURFACE DIPOLE MODE AND DIAGNOSTIC ANALYSIS OF DIPOLE EVENT IN 1997/ 1998

1.
Department of Atmospheric Sciences, Nanjing University, Nanjing 210093
2.
Chinese Academy of Meteorological Sciences, Beijing 100081

Received Date: 2002-03-19
Rev Recd Date: 2002-06-04
Publish Date: 2003-04-30

Abstract

Abstract

The tropical Indian Ocean subsurface temperature anomaly above 400 m is studied by using the method of EOF and other statistic methods, and the 1997/98 tropical Indian Ocean dipole event is analyzed.The results show that the largest temperature anomaly in the tropical Indian Ocean subsurface layer above 400 m is around the depth of 100 m.As for the whole tropical Indian Ocean, the subsurface layer above 60 m appears to have a warming trend since the 1980' s, while the subsurface layer below 80 m to have a cooling trend.The subsurface layer of 80 m has an obvious dipole mode, which is much stronger than that of the sea surface.In 1997/98, the dipole event of the sea surface in the Indian Ocean was resulted from the westward ex tension of the temperature anomaly over the eastern Indian Ocean.The westward ex tension of the temperature anomaly was related to the easterly anomaly over the tropical Indian Ocean, where the easterly anomaly might trigger the Rossby wave and induce the temperature anomaly to ex tend westward.
- Tropical Indian Ocean;
- Subsurface layer;
- Dipole mode;
- Temperature anomaly

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References(14)

Figures and Tables

图 1 热带印度洋 (50°E~110°E, 10°N~15°S) 平均海温距平的时间序列

(经过13个月低通滤波处理)(单位:℃)(a)0m, (b)160m

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图 2 各海域区域平均后的次表层温度距平的均方差沿深度的垂直剖面图 (单位:℃)

(a) 热带印度洋地区:10°S~15°N, 50°E~110°E, (b) Nino3区:5°S~5°N, 150°E~90°W, (c) DMI

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图 3 13个月低通滤波后热带印度洋次表层各层的偶极子指数的时间序列

(a)0m, (b)80m

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图 4 热带印度洋次表层温度距平作EOF分解得到的第一空间模 (EOF1) 和对应的时间序列 (图中阴影区为主分量PC1和海温异常相关达到95%显著性水平的区域)

(a)0m的EOF1, (b)0m对应的时间序列PC1, (c)80m的EOF1, (d)80m对应的时间序列PC1

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图 5 热带印度洋次表层5°S~5°N平均的温度距平的时间-经度剖面图 (阴影部分的区域海温距平绝对值超过了0.5℃)

(a)20m, (b)80m

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图 6 不同月份的热带印度洋沿赤道海温距平的垂直剖面图 (阴影部分的区域海温距平绝对值超过了0.5℃)

(a)1996年11月, (b)1997年6月, (c)1997年12月, (d)1998年3月

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图 7 (a) 印度洋上1000hPa风场异常沿赤道的时间-经度剖面图 (单位:m/s, 等值线为80m处的温度距平分布, 单位:℃)(b) 印度洋地区OLR5°S~5°N平均沿赤道的时间-经度剖面图 (阴影部分区域的绝对值超过了40, 单位:W/m2)

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