Transport and variability of the Antarctic Circumpolar Current south of Africa
Transport and variability of the Antarctic Circumpolar Current south of Africa
复制标题
非洲南部南极绕极流的输送和变化
DOI：
10.1029/2007jc004223
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发表时间：
2008
影响因子：
--
通讯作者：
J. Lutjeharms
中科院分区：
文献类型：
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作者：
S. Swart;S. Speich;I. Ansorge;G. Goñi;S. Gladyshev;J. Lutjeharms
利用5个CTD和18个XBT断面的资料，估算了非洲南部ACC的斜压输送（参考2500毫巴）。通过建立垂直积分温度与由CTD数据计算的地面动力高度之间的经验关系，由XBT数据推导出地面动力高度。该温度导出的动态高度数据与根据CTD数据计算的动态高度非常接近（平均RMS差异= 0.05达因m）。第二个经验之间的关系，表面动力高度和累积斜压输送的定义，使我们能够研究更广泛的斜压输送来自上层海洋温度段的时间序列。根据ACC的18个XBT断面，平均斜压输送，相对于2500 dbar，估计为90 +/- 2.4 Sv。这一估计值与由CTD数据计算的斜压输送值相当。然后，我们扩展的斜压运输时间序列应用动态高度和累积斜压运输的绝对动态地形从卫星测高，1992年10月14日和2007年5月23日之间的每周地图之间的经验关系。用这种方法得到的ACC的平均斜压输送估计为84.7 +/- 3.0 Sv。这些运输同意以及同时在原位估计（RMS差异净运输= 5.2西沃特）。这表明海平面异常在很大程度上反映了2500 dbar以上的斜压输送变化。
Data from five CTD and 18 XBT sections are used to estimate the baroclinic transport ( referenced to 2500 dbar) of the ACC south of Africa. Surface dynamic height is derived from XBT data by establishing an empirical relationship between vertically integrated temperature and surface dynamic height calculated from CTD data. This temperature-derived dynamic height data compare closely with dynamic heights calculated from CTD data ( average RMS difference = 0.05 dyn m). A second empirical relationship between surface dynamic height and cumulative baroclinic transport is defined, allowing us to study a more extensive time series of baroclinic transport derived from upper ocean temperature sections. From 18 XBT transects of the ACC, the average baroclinic transport, relative to 2500 dbar, is estimated at 90 +/- 2.4 Sv. This estimate is comparable to baroclinic transport values calculated from CTD data. We then extend the baroclinic transport time-series by applying an empirical relationship between dynamic height and cumulative baroclinic transport to weekly maps of absolute dynamic topography derived from satellite altimetry, between 14 October 1992 and 23 May 2007. The estimated mean baroclinic transport of the ACC, obtained this way, is 84.7 +/- 3.0 Sv. These transports agree well with simultaneous in-situ estimates ( RMS difference in net transport = 5.2 Sv). This suggests that sea level anomalies largely reflect baroclinic transport changes above 2500 dbar.