The Cold Transit of Southern Ocean Upwelling
The Cold Transit of Southern Ocean Upwelling
复制标题
DOI：
10.1029/2018gl079986
复制
发表时间：
2018-12
影响因子：
5.2
通讯作者：
D. G. Evans;J. Zika;A. N. Naveira Garabato;A. Nurser
中科院分区：
文献类型：
--
作者：
D. G. Evans;J. Zika;A. N. Naveira Garabato;A. Nurser
南大洋深层沃茨的涌升是气候系统的一个重要组成部分。该环流的时间和纬向平均动力学特征描述了环极深层水的上升流和南极中层水的下降流。环流的热力学驱动因素及其季节性循环发挥着潜在的关键调节作用。在这里，从热力学的角度分析了观测约束的海洋模式和基于观测的季节气候学，以评估控制南大洋翻转的非绝热过程。这揭示了从上升的深水形成中间水的季节性两阶段冷过境。首先，相对温暖和含盐的深水通过冬季混合转化为更冷，更新鲜的近地表冬季水。第二，冬季水变暖，形成中间水通过夏季表面热通量。从深水到冬季水的混合驱动路径遵循指示非线性过程的温盐坐标中的混合线。
The upwelling of deep waters in the Southern Ocean is a critical component of the climate system. The time and zonal mean dynamics of this circulation describe the upwelling of Circumpolar Deep Water and the downwelling of Antarctic Intermediate Water. The thermodynamic drivers of the circulation and their seasonal cycle play a potentially key regulatory role. Here an observationally constrained ocean model and an observation‐based seasonal climatology are analyzed from a thermodynamic perspective, to assess the diabatic processes controlling overturning in the Southern Ocean. This reveals a seasonal two‐stage cold transit in the formation of intermediate water from upwelled deep water. First, relatively warm and saline deep water is transformed into colder and fresher near‐surface winter water via wintertime mixing. Second, winter water warms to form intermediate water through summertime surface heat fluxes. The mixing‐driven pathway from deep water to winter water follows mixing lines in thermohaline coordinates indicative of nonlinear processes.