Diapycnal and isopycnal mixing along the continental rise in the Australian?Antarctic Basin
Diapycnal and isopycnal mixing along the continental rise in the Australian?Antarctic Basin
复制标题
澳大利亚南极盆地沿大陆隆升的双重和等重混合
DOI：
10.1016/j.pocean.2023.102979
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发表时间：
2023
影响因子：
4.1
通讯作者：
Yamazaki Kaihe
中科院分区：
文献类型：
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作者：
Katsumata Katsuro;Yamazaki Kaihe
船上测量的温度、盐度和水平洋流速度被用来估计南大洋澳大利亚区在120°E到150°E之间，在64°S附近，沿南南极环极流锋面和南边界的气候位置的横环流和等环流扩散系数。在1028.05、1028.2和1028.3 kg m−3的中性密度表面上，用细尺度参数化估计的内周期扩散系数为(9)。5±6。8)× 10−5；7±2。6)× 10−5；8±3。7)× 10−5 m²s−1（平均值±1个标准差）。在这些密度下，盐度和温度随深度降低，但不太可能发生盐指化。利用水质量转换框架和箱形逆模型，由准周期扩散系数估算出等周期扩散系数。在上环极深水、下环极深水和南极底水密度范围内等环流扩散系数的气候估计分别为- 30±116、16±319和- 30±83 m 2 s−1。这些扩散系数可能被低估了10到20 m2 s−1，因为在气候资料中没有考虑涡动输送。弱等压风扩散系数与锋面射流抑制的扩散系数不一致。较大的不确定性是由于箱形逆模型的不确定性以及箱形的大小与平流速度乘以扩散时间尺度相当。
Shipboard measurements of temperature, salinity and horizontal current velocity were used to estimate diapycnal and isopycnal diffusivities in the Australian sector of the Southern Ocean between 120∘ E and 150∘ E near 64∘ S, along the climatological positions of the Southern Antarctic Circumpolar Current Front and the Southern Boundary. The diapycnal diffusivities estimated by the finescale parameterization on the neutral density surfaces of 1028.05, 1028.2, and 1028.3 kg m− 3 are (9. 5±6. 8)× 1 0− 5,(10. 7±2. 6)× 1 0− 5, and (13. 8±3. 7)× 1 0− 5 m 2 s− 1, respectively (mean±one standard deviation). At these densities, salinity and temperature decreased with depth but salt fingering was unlikely. Using the water mass transformation framework and a box inverse model, the isopycnal diffusivities were estimated from the diapycnal diffusivities. Climatological estimates of the isopycnal diffusivities in the density ranges of Upper Circumpolar Deep Water, Lower Circumpolar Deep Water, and Antarctic Bottom Water were− 30±116, 16±319, and− 30±83 m 2 s− 1, respectively. These diffusivities were likely underestimates by 10 to 20 m 2 s− 1 because eddy transport could not be considered in the climatological data. The weak isopycnal diffusivities were not inconsistent with diffusivity suppressed by the frontal jets. The large uncertainties were caused by the uncertainty in the box inverse model and the fact that the size of the box was comparable to the advection speed times the diffusion time scale.