| Annual and interannual variations of sea-level anomaly in the Bay of Bengal and the Andaman Sea |
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| 作者姓名： | QIU Yun LI Li YU Weidong HU Jianyu |
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| 作者单位： | QIU Yun1，2，LI Li2，YU Weidong3，HU Jianyu11.State key Laboratory of Marine Environmental Science，College of Oceanography and Environmental Science，Xiamen University，Xiamen 361005，China2.Third Institute of Oceanography，State Oceanic Administration，Xiamen 361005，China3.First Institute of Oceanography，State Oceanic Administration，Qinddao 266061，China |
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| 基金项目： | The Chinese MOST
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国家自然科学基金
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The Chinese SOAYF |
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| 摘 要： | Annual and interannual variations of sea-level anomaly (SLA) in the Bay of Bengal and the Andaman Sea are investigated using altimeter-derived SLA data from 1993 to 2003. It is found that the SLA annual variation in the study area can be divided into three phases with distinctive patterns. During the southwest monsoon (May-September), positive SLA presents in the equatorial region and extends northward along the eastern boundary of the bay, and the SLA distribution in the interior bay appears to be high in the east and low in the west with two cyclonic cells developing in the north and south of the western bay respectively, between which an anticyclonic cell exists. During the early northeast monsoon (October-December), the whole bay is dominated by a large cyclonic cell with the pattern of high SLA in the east and low in the west still retained, and the SLA distribution outside the bay is changed in response to the reversal of the Indian Monsoon Current (IMC) in November. During the late northeast monsoon (January-April), a large anticyclonic cell of SLA develops in the bay with negative SLA prevailing in the equatorial region and extending northward along the eastern boundary of bay. Therefore, the SLA distribution in the interior bay reverses to be high in the west and low in the east. It is suggested that the SLA annual variation in the bay is primarily driven by the local wind stress curl, involving Sverdrup balance while the abrupt SLA variation during the peak of northeast monsoon may be partly caused by the semiannual fluctuation of wind in the equatorial region. This fast adjustment in the interior bay is induced by the upwelling coastal Kelvin wave excited by the decay of Wyrtki jet during December through January. Besides the annual variation, in the bay, there are obvious SLA fluctuations with the periods of 2 and 3~7 a, which are driven by the interannual variability of large-scale wind field in the equatorial region. The coastal Kelvin wave also provides an important link for the SLA interannual variation between the equatorial region and the interior bay. It is found that the El Nio-Southern Oscillation (ENSO)-induced influence on the SLA interannual variation in the interior bay is stronger than the Indian Ocean dipole (IOD) with the associated pattern of low sea-level presenting along the periphery of the bay and high sea-level in the northeast of Sri Lanka.
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| 关 键 词： | 孟加拉海湾 海平面 低频率变化 人造卫星高度计 |
| 收稿时间： | 2006-07-28 |
| 修稿时间： | 2007-02-05 |
Annual and interannual variations of sea-level anomaly in the Bay of Bengal and the Andaman Sea |
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| QIU Yun,LI Li,YU Weidong,HU Jianyu.Annual and interannual variations of sea-level anomaly in the Bay of Bengal and the Andaman Sea[J].Acta Oceanologica Sinica,2007,26(6):13-29. |
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| Authors: | QIU Yun LI Li YU Weidong and HU Jianyu |
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| Institution: | State key Laboratory of Marine Environmental Science, College of Oceanography and Environmental Science, Xiamen University, Xiamen 361005, China;Third Institute of Oceanography, State Oceanic Administration, Xiamen 361005, China;Third Institute of Oceanography, State Oceanic Administration, Xiamen 361005, China;First Institute of Oceanography, State Oceanic Administration, Qinddao 266061, China;State key Laboratory of Marine Environmental Science, College of Oceanography and Environmental Science, Xiamen University, Xiamen 361005, China |
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| Abstract: | Annual and interannual variations of sea-level anomaly (SLA) in the Bay of Bengal and the Andaman Sea are investigated using altimeter-derived SLA data from 1993 to 2003. It is found that the SLA annual variation in the study area can be divided into three phases with distinctive patterns. During the southwest monsoon (May-September), positive SLA presents in the equatorial region and extends northward along the eastern boundary of the bay, and the SLA distribution in the interior bay appears to be high in the east and low in the west with two cyclonic cells developing in the north and south of the western bay respectively, between which an anticyclonic cell exists. During the early northeast monsoon (October-December), the whole bay is dominated by a large cyclonic cell with the pattern of high SLA in the east and low in the west still retained, and the SLA distribution outside the bay is changed in response to the reversal of the Indian Monsoon Current (IMC) in November. During the late northeast monsoon (January-April), a large anticyclonic cell of SLA develops in the bay with negative SLA prevailing in the equatorial region and extending northward along the eastern boundary of bay. Therefore, the SLA distribution in the interior bay reverses to be high in the west and low in the east. It is suggested that the SLA annual variation in the bay is primarily driven by the local wind stress curl, involving Sverdrup balance while the abrupt SLA variation during the peak of northeast monsoon may be partly caused by the semiannual fluctuation of wind in the equatorial region. This fast adjustment in the interior bay is induced by the upwelling coastal Kelvin wave excited by the decay of Wyrtki jet during December through January. Besides the annual variation, in the bay, there are obvious SLA fluctuations with the periods of 2 and 3～7 a, which are driven by the interannual variability of large-scale wind field in the equatorial region. The coastal Kelvin wave also provides an important link for the SLA interannual variation between the equatorial region and the interior bay. It is found that the El Nino-Southern Oscillation (ENSO)-induced influence on the SLA interannual variation in the interior bay is stronger than the Indian Ocean dipole (IOD) with the associated pattern of low sea-level presenting along the periphery of the bay and high sea-level in the northeast of Sri Lanka. |
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| Keywords: | Bay of Bengal sea-level anomaly low-frequency variation satellite altimeter |
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