| 赤道东印度洋和孟加拉湾障碍层厚度的季节内和准半年变化 |
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| 引用本文： | 马天,齐义泉,程旭华.赤道东印度洋和孟加拉湾障碍层厚度的季节内和准半年变化[J].热带海洋学报,2019,38(5):18-31. |
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| 作者姓名： | 马天 齐义泉 程旭华 |
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| 作者单位： | 1. 热带海洋环境国家重点实验室(中国科学院南海海洋研究所), 广东 广州 510301;2. 中国科学院大学, 北京 100049;3. 河海大学海洋学院, 江苏 南京 210098 |
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| 基金项目： | 国家重点研发计划课题(2018YFA0605702);国家自然科学基金(41522601);国家自然科学基金(41876002);国家自然科学基金(41876224);中央高校基本科研业务费项目)(2017B04714);中央高校基本科研业务费项目(2017B04114) |
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| 摘 要： | 利用2002—2015年ARGO网格化的温度、盐度数据, 结合卫星资料揭示了赤道东印度洋和孟加拉湾障碍层厚度的季节内和准半年变化特征, 探讨了其变化机制。结果表明, 障碍层厚度变化的两个高值区域出现在赤道东印度洋和孟加拉湾北部。在赤道区域, 障碍层同时受到等温层和混合层变化的影响, 5—7月和11—1月受西风驱动, Wyrtki急流携带阿拉伯海的高盐水与表层的淡水形成盐度层结, 同时西风驱动的下沉Kelvin波加深了等温层, 混合层与等温层分离, 障碍层形成。在湾内, 充沛的降雨和径流带来的大量淡水产生很强的盐度层结, 混合层全年都非常浅, 障碍层季节内变化和准半年变化主要受等温层深度变化的影响。上述两个区域障碍层变化存在关联, 季节内和准半年周期的赤道纬向风驱动的波动过程是它们存在联系的根本原因。赤道东印度洋地区的西风(东风)强迫出向东传的下沉(上升)的Kelvin波, 在苏门答腊岛西岸转变为沿岸Kelvin波向北传到孟加拉湾的东边界和北边界, 并且在缅甸的伊洛瓦底江三角洲顶部(95°E, 16°N)激发出向西的Rossby波, 造成湾内等温层深度的正(负)异常, 波动传播的速度决定了湾内的变化过程滞后于赤道区域1~2个月。
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| 关 键 词： | 障碍层 季节内变化 准半年变化 孟加拉湾 赤道东印度洋 |
| 收稿时间： | 2018-11-29 |
| 修稿时间： | 2019-03-03 |
Intraseasonal-to-semiannual variability of barrier layer thickness in the eastern equatorial lndian Ocean and Bay of Bengal |
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| Tian MA,Yiquan QI,Xuhua CHENG.Intraseasonal-to-semiannual variability of barrier layer thickness in the eastern equatorial lndian Ocean and Bay of Bengal[J].Journal of Tropical Oceanography,2019,38(5):18-31. |
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| Authors: | Tian MA Yiquan QI Xuhua CHENG |
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| Institution: | 1. State Key Laboratory of Tropical Oceanography (South China Sea Institute of Oceanology, Chinese Academy of Sciences), Guangzhou 510301, China;2. University of Chinese Academy of Sciences, Beijing 100049, China;3. College of Oceanography, Hohai University, Nanjing, 210098, China |
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| Abstract: | Based on the gridded temperature and salinity data of ARGO and satellite observations from 2002 to 2015, the intraseasonal-to-semiannual variability of barrier layer (BL) in the eastern equatorial Indian Ocean (EEIO) and Bay of Bengal (BOB) is revealed, and its variation mechanism is discussed. The results show that strong variation of barrier layer thickness (BLT) is located in the EEIO and northern BOB. In the equatorial region, the variability in BLT is affected by both isothermal layer depth (ILD) and mixing layer depth (MLD). From May to July and from November to January, driven by westerly winds, the Wyrtki jet carries high-salinity water from the Arabian Sea to the eastern equatorial region, forming salinity stratification with fresh water on the surface. The downwelling Kelvin wave, which is also driven by westerly winds, deepens the isothermal layer. Then, the isothermal layer separates from the mixed layer. The barrier layer is formed. In the northern BOB, a large amount of fresh water brought by abundant rainfall and runoff produces strong salinity stratification near the surface, which causes the mixed layer to be very shallow all year round. The intraseasonal-to-semiannual variability in BLT is mainly controlled by ILD. A dynamic correlation exists between the two high value regions. The equatorial westerly (easterly) winds force the downwelling (upwelling) Kelvin wave to spread eastward, and it turns into a coastal Kelvin wave when arriving at Sumatra Island; then, the waves propagate northward to the eastern and northern boundaries of the BOB. In addition, at the top of Burma's Irrawaddy Delta, the coastal Kelvin wave radiates Rossby waves that cause positive (negative) anomalies of ILD in the bay. The wave speed determines the change in the bay, which lags the equatorial region by 1~2 months. |
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| Keywords: | barrier layer thickness intraseasonal variability semiannual variability eastern equatorial Indian Ocean Bay of Bengal |
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