印度洋混合层盐度季节变化机制研究

许金电; 邱云; 靖春生; 高璐; 林新宇

doi:10.12284/hyxb2021162

印度洋混合层盐度季节变化机制研究

doi: 10.12284/hyxb2021162

1.
自然资源部第三海洋研究所海洋动力学实验室，福建厦门 361005
2.
国家海洋局海口海洋环境监测中心站，海南海口 570311

基金项目: 科技基础资源调查专项（2017FY201402）；国家自然科学基金（42130460）；亚洲合作基金（99950410）；全球变化与海气相互作用专项（GASI-IPOVAI-02，GASI-IPOVAI-03）；自然资源部第三海洋研究所基本科研业务费专项（海三科2018001，海三科2017012，海三科2018030）；国家自然科学基金青年科学基金（41906013）

详细信息

作者简介:
许金电（1963—），男，福建省晋江市人，高级工程师，主要从事热带边缘海海洋动力学研究。E-mail：xujindian@tio.org.cn

中图分类号: P731.12
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出版历程
- 收稿日期: 2020-12-03
- 修回日期: 2021-01-26
- 网络出版日期: 2021-08-17
- 刊出日期: 2021-12-31

Mechanisms of the seasonal variability of mixed-layer salinity in the Indian Ocean

1.
Laboratory of Marine Dynamics, Third Institute of Oceanography, Ministry of Natural Resources, Xiamen 361005, China
2.
Haikou Marine Environment Monitoring Station, State Oceanic Administration, Haikou 570311, China

摘要

摘要: 本文利用Argo盐度、SODA海流量、OAFlux蒸发量和TRMM降水量等数据，采用盐度收支方程定量给出了印度洋混合层盐度的收支，揭示了整个印度洋净淡水通量项、平流项、垂向卷夹项的分布、季节变化特征及其对混合层盐度变化的主要贡献。结果表明，就多年平均而言，平流项负贡献（15.14%）大于正贡献（9.89%），说明平流输送把低盐水输送到高盐海域，导致印度洋高盐海域混合层的盐度降低。净淡水通量项的分布和季节变化与降水量基本一致，且正贡献（13.70%）大于负贡献（7.81%），说明净淡水通量项使印度洋的混合层盐度升高（因为多年平均蒸发量大于降水量）。盐度季节变化显著海域的进一步分析表明，6−11月，西南季风漂流把赤道西印度洋的低盐水（相对阿拉伯海高盐水而言）输送到阿拉伯海西部海域，导致该海域的盐度降低。平流输送把孟加拉湾湾口和中部的高盐水带到北部海域，是导致北部海域盐度升高的主要原因。
- 盐度收支 /
- 机制 /
- 混合层 /
- 印度洋
Abstract: In this study, we quantify the mixed-layer salinity (MLS) budget in the Indian Ocean using the salinity budget equation along with Argo salinity, SODA ocean current, evaporation, and precipitation data. The results show that the distribution and seasonal variability for the terms of freshwater flux, advection and entrainment in the Indian Ocean, and their contributions to the variations of MLS. Regarding the climatological annual mean, the negative contribution (15.14%) of the horizontal advection term to MLS is much larger than its positive contribution (9.89%). This implies that the horizontal advection transports low-salinity water to the salty regions, resulting in a decrease in MLS there. The distribution and seasonal variability of the freshwater flux term are generally consistent with those of precipitation, with a positive contribution (13.70%) higher than negative contribution (7.81%). It suggests that the freshwater flux term increases MLS in the Indian Ocean because of the evaporation overwhelming the precipitation. Analysis on the regions with significant seasonal variations of MLS indicates that from June to November, the Southwest Monsoon Current transports low-salinity water from the western equatorial Indian Ocean to the western Arabian Sea, causing salinity in that region to decrease. The advection of high-salinity water from the southern and central to the northern of Bengal Bay is the main reason for the increase in salinity there.
- salinity budget /
- mechanism /
- mixed-layer /
- Indian Ocean

HTML全文

图 1 印度洋多年平均月降水量（a）、月蒸发量（b）、混合层深度（c）和混合层平均盐度（d）的平面分布

Fig. 1 Distribution of mean monthly precipitation (a), monthly evaporation (b), mixed-layer depth (c), and mixed-layer salinity (d) in the Indian Ocean

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图 2 印度洋多年平均1月（a）、4月（b）、7月（c）、10月（d）净淡水通量项（填充颜色）和降水量（等值线，单位：mm）的平面分布

Fig. 2 Horizontal distribution of the multiyear averages of net freshwater flux term (shaded) and precipitation (contours, unit: mm) in January (a), April (b), July (c), and October (d) of the Indian Ocean

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图 3 印度洋多年平均1月、7月平流项和流速矢量的平面分布

Fig. 3 Horizontal distribution of the multiyear averages of advection term and the surface circulation in January and July of the Indian Ocean

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图 4 印度洋多年平均1月、7月垂向卷夹项（单位：月⁻¹）和盐度差（混合层平均盐度与混合层底盐度之差）的平面分布

Fig. 4 Horizontal distributions of the multiyear averages of the vertical entrainment and salinity difference in January and July of the Indian Ocean

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图 5 印度洋净淡水通量项、平流项（填充颜色）和降水量（等值线，单位：mm）的纬度−时间分布

Fig. 5 Zonal-temporal distribution of the net freshwater flux term (shaded), advection term (shaded), and precipitation (contours, unit: mm) in the Indian Ocean

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图 6 印度洋1月（a）、4月（b）、7月（c）、10月（d）净淡水通量项的贡献的分布

Fig. 6 Distributions of the contribution of the net freshwater flux term in January (a), April (b), July (c), and October (d) of the Indian Ocean

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图 7 印度洋1月（a）、4月（b）、7月（c）、10月（d）平流项的贡献的分布

Fig. 7 Distributions of the contribution of the advection term in January (a), April (b), July (c), and October (d) of the Indian Ocean

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图 8 印度洋1月（a）、4月（b）、7月（c）、10月（d）各项的值大于0.08月⁻¹且正贡献大于50%的分布

Fig. 8 Distributions of the terms with values greater than 0.08 month⁻¹ and positive contributions greater than 50% during January (a), April (b), July (c), and October (d) of the Indian Ocean

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图 9 印度洋1月（a）、4月（b）、7月（c）、10月（d）各项的值（绝对值）大于0.08月⁻¹且负贡献的值大于50%的分布

Fig. 9 Distributions of the terms with absolute values greater than 0.08 month⁻¹ and negative contributions greater than 50% during January (a), April (b), July (c), and October (d) of the Indian Ocean

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图 10 印度洋各项贡献大于50%的平均值

Fig. 10 Means of the terms with contributions over 50% in the Indian Ocean

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图 11 印度洋混合层盐度季节方差和讨论区域

Fig. 11 Seasonal deviation of mixed-layer salinity in the Indian Ocean

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图 12 各区域月平均的盐度−时间变化项、净淡水通量项、平流项、垂向卷夹项、余项和孟加拉湾12条主要河流总流量的时间序列

Fig. 12 The regional means of the monthly variation of salinity, net freshwater flux, advection, vertical entrainment, and residual terms, as well as the time series of the total discharge of the 12 major rivers into the Bay of Bengal

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