| MA Jie,LAN Jian,ZHANG Ningning. 2016. A study of Indian Ocean Subtropical Mode Water: subduction rate and water characteristics. Acta Oceanologica Sinica, 35(1):38－45 |
| A study of Indian Ocean Subtropical Mode Water: subduction rate and water characteristics |
| 关于印度洋副热带模态水的研究:潜沉率及其水体性质 |
| Received:October 22, 2014 Revised:March 23, 2015 |
| DOI：10.1007/s13131-016-0794-0 |
| Key words:Indian Ocean Subtropical Mode Water subduction rate the layer of minimum vertical temperature gradient water characteristics |
| 中文关键词: 印度洋副热带模态水 潜沉率 垂向温度梯度极小值 水体性质 |
| 基金项目: |
| Author Name | Affiliation | E-mail | | MA Jie | Physical Oceanography Laboratory, Ocean University of China, Qingdao 266100, China
College of Oceanic and Atmospheric Sciences, Ocean University of China, Qingdao 266100, China | | | LAN Jian | Physical Oceanography Laboratory, Ocean University of China, Qingdao 266100, China
College of Oceanic and Atmospheric Sciences, Ocean University of China, Qingdao 266100, China | lanjian@ouc.edu.cn | | ZHANG Ningning | Physical Oceanography Laboratory, Ocean University of China, Qingdao 266100, China
College of Oceanic and Atmospheric Sciences, Ocean University of China, Qingdao 266100, China | |
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| Abstract: |
| The annual subduction rate in the South Indian Ocean was calculated by analyzing Simple Ocean Data Assimilation (SODA) outputs in the period of 1950-2008. The subduction rate census for potential density classes showed a peak corresponding to Indian Ocean subtropical mode water (IOSTMW) in the southwestern part of the South Indian Ocean subtropical gyre. The deeper mixed layer depth, the sharper mixed-layer fronts and the associated relatively faster circulation in the present climatology resulted in a larger lateral induction, which primarily dominants the IOSTMW subduction rate, while with only minor contribution from vertical pumping. Without loss of generality, through careful analysis of the water characteristics in the layer of minimum vertical temperature gradient (LMVTG), the authors suggest that the IOSTMW was identified as a thermostad, with a lateral minimum of low potential vorticity (PV, less than 200×10-12 m-1·s-1) and a low dT/dz (less than 1.5°C/(100 m)). The IOSTMW within the South Indian Ocean subtropical gyre distributed in the region approximately from 25° to 50° E and from 30° to 39°S. Additionally, the average characteristics (temperature, salinity, potential density) of the mode water were estimated about (16.38 ± 0.29)°C, (35.46 ± 0.04), (26.02 ± 0.04) σθ over the past 60 years. |
| 中文摘要: |
| 通过分析1950-2008年的SODA资料对印度洋区域的潜沉率进行了计算。在副热带西南印度洋区域,以位势密度为函数的潜沉率峰值对应着印度洋副热带模态水的密度分布区间。在副热带模态水生成区,潜沉率主要是由深的混合层,强大的混合层锋面以及相对快速的流场组合所产生的强的侧向导入项控制的,而垂直抽吸项对潜沉率贡献较小。为了不失一般性,根据对垂向温度梯度极小值所在层的水体性质进行细致分析,我们认为印度洋副热模态水是温度均一的巨大水体,且具有较小的位势涡度(<200 10-12 m-1s-1)以及弱的垂向温度梯度(< 1.5 ℃/100米)。印度洋副热带模态水大致分布在印度洋副热带区域:东经25°-50°,南纬30°-39°。此外,我们计算了最近60年左右印度洋副热带模态水气候态平均性质:温度(16.38 0.29, 盐度(35.46±0.04), 位势密度(26.02±0.04) σθ。 |
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