Meridional transport of salt in the global ocean from an eddy-resolving model
Meridional transport of salt in the global ocean from an eddy-resolving model
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根据涡旋解析模型研究全球海洋中盐的经向输送
DOI：
10.5194/os-10-243-2014
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发表时间：
2013
期刊：
影响因子：
3.2
通讯作者：
C. Talandier
中科院分区：
文献类型：
--
作者：
A. Treguier;J. Deshayes;J. Sommer;C. Lique;G. Madec;T. Penduff;J. Molines;B. Barnier;R. Bourdallé‐Badie;C. Talandier
在一个全球涡旋分辨数值模式（1/12°分辨率）中计算了盐的纬向输运，以提高我们对海洋盐度收支的理解。提出了一种方法，允许全球分析与地表水通量有关的盐度平衡，而无需根据任意参考盐度定义“淡水异常”。该方法包括一个分解成（i）运输的时间-经度-深度平均速度，（ii）时间平均速度回流和（iii）瞬态涡流扰动的纬向输送。水在不同纬度的海洋表面增加（降雨和河流）或去除（蒸发），这造成了质量传输的收敛和发散，最大和最小值接近±1 Sv。由此产生的纬向速度在每个纬度（±30 Sv PSU）影响盐的净输送，这是由时间平均再循环和涡动盐度-速度相关的净效应平衡。这种平衡确保了盐的总纬向输送接近于零，这是维持准静态盐度分布的必要条件。我们的模型证实，涡流盐运输不能被忽视：它是可比的时间平均再循环（高达15 Sv PSU）在极向和赤道边界的副热带环流的运输。两种不同的机制被发现：涡动的贡献是本地化的强电流，如黑潮在极向边界的副热带环流，而它们分布在整个盆地的赤道边界。在靠近赤道的地方，盐度-速度的相关性主要是由于季节性周期和大尺度扰动，如热带不稳定波。
The meridional transport of salt is computed in a global eddy-resolving numerical model (1/12° resolution) in order to improve our understanding of the ocean salinity budget. A methodology is proposed that allows a global analysis of the salinity balance in relation to surface water fluxes, without defining a "freshwater anomaly" based on an arbitrary reference salinity. The method consists of a decomposition of the meridional transport into (i) the transport by the time–longitude–depth mean velocity, (ii) time–mean velocity recirculations and (iii) transient eddy perturbations. Water is added (rainfall and rivers) or removed (evaporation) at the ocean surface at different latitudes, which creates convergences and divergences of mass transport with maximum and minimum values close to ±1 Sv. The resulting meridional velocity effects a net transport of salt at each latitude (±30 Sv PSU), which is balanced by the time–mean recirculations and by the net effect of eddy salinity–velocity correlations. This balance ensures that the total meridional transport of salt is close to zero, a necessary condition for maintaining a quasi-stationary salinity distribution. Our model confirms that the eddy salt transport cannot be neglected: it is comparable to the transport by the time–mean recirculation (up to 15 Sv PSU) at the poleward and equatorial boundaries of the subtropical gyres. Two different mechanisms are found: eddy contributions are localized in intense currents such as the Kuroshio at the poleward boundary of the subtropical gyres, while they are distributed across the basins at the equatorward boundaries. Closer to the Equator, salinity–velocity correlations are mainly due to the seasonal cycle and large-scale perturbations such as tropical instability waves.