Subtropical mode waters in the South Atlantic Ocean
Subtropical mode waters in the South Atlantic Ocean
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DOI：
10.1029/1999jc900049
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发表时间：
1999-09
影响因子：
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通讯作者：
C. Provost;C. Escoffier;K. Maamaatuaiahutapu;A. Kartavtseff;V. Garçon
中科院分区：
文献类型：
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作者：
C. Provost;C. Escoffier;K. Maamaatuaiahutapu;A. Kartavtseff;V. Garçon
对南大西洋副热带模式沃茨的系统研究是基于水文数据（全流域的南大西洋通风实验、Oceanus和Ajax剖面，以及巴西-马尔维纳斯汇流区的世界海洋环流实验剖面）、世界海洋环流实验一次性深海温度计数据集，以及国家环境预测再分析中心产生的大气强迫。副热带环流的主要通风窗口位于西南部，对应于回流区的南部和巴西洋流（BC）的过冲。有些通风发生沿着南分支的环流通过深混合层在严酷的冬天，并在东部通过环脱落的阿古拉斯电流。然而，来自东部边界的通风涉及具有高度可变特性的少量水。观测到的副热带模态水主要有三种类型：密度为26.2的面附近最轻，密度为26.5和26.7的面附近分别为第二和第三类。26.2亚热带模态水（STMW 1）对应的潜在温度在16 ° C和18 ° C之间，盐度在35.9和36.2之间。STMW 1厚度不超过150 m。26.5模水（STMW 2）的体积较大。它是通过在BC超调上方的主动通风窗口中形成深混合层（达到300 m或更高）而产生的。其潜在温度在14 ° C至16 ° C之间，盐度在35.5至35.9之间。其厚度可达300 m以上。在26.7密度表面（STMW3）周围观察到的最后一个组件的潜在温度在12 ° C和14 ° C之间，盐度约为35.2至35.5。它形成于BC过冲的东侧，在严冬期间，位于环流南部分支的中心。在主通气窗内，STMW在特征和体积上表现出相当显著的变化。在BC环流和BC延伸区，大气强迫存在较大的年际变率，观测到的副热带模态沃茨变化与大气强迫的变化有定性的相关性。
This systematic study of the subtropical mode waters in the South Atlantic is based on hydrological data (the basin-wide South Atlantic Ventilation Experiment, Oceanus, and Ajax sections, and the World Ocean Circulation Experiment (WOCE) sections in the Brazil-Malvinas Confluence region), the WOCE expendable bathythermograph data set, and the atmospheric forcing produced by the National Centers for Environmental Prediction reanalysis. The main ventilation window of the subtropical gyre lies in the southwest and corresponds to the southern part of the recirculation region and to the overshoot of the Brazil Current (BC). Some ventilation occurs along the southern branch of the gyre through deep mixed layers in harsh winters and in the east through the rings shed by the Agulhas Current. However, the ventilation from the eastern border concerns a small volume of water with highly variable characteristics. Three main types of subtropical mode water are observed: the lightest around the 26.2 density surface and the second and third around the 26.5 and 26.7 density surfaces, respectively. The 26.2 subtropical mode water (STMW1) corresponds to potential temperatures between 16° and 18°C and salinities between 35.9 and 36.2. The STMW1 thickness does not exceed 150 m. The volume of the 26.5 mode water (STMW2) is larger. It is produced through the formation of deep mixed layers (reaching 300 m or more) in the active ventilation window over the BC overshoot. Its potential temperature ranges between 14° and 16°C, and its salinity ranges between 35.5 and 35.9. Its thickness can be above 300 m. The last component observed around the 26.7 density surface (STMW3) has a potential temperature between 12° and 14°C and a salinity of about 35.2 to 35.5. It is formed on the eastern flank of the BC overshoot and, during harsh winters, in the center of the southern branch of the gyre. Within the main ventilation window the STMWs exhibit quite a significant variability in characteristics and volume. There is a large interannual variability in the atmospheric forcing over the BC recirculation and BC extension, and the observed variations of the subtropical mode waters are qualitatively correlated to the atmospheric forcing variations.