Distributions of diapycnal, isopycnal, and thickness diffusivity coefficients were estimated using long-term (2001–2015) mean salinity distributions on neutral density (γ) surfaces in seven oceanic basins (except the equatorial region). Diffusivity amplitudes and spatial differences were consistent with distributions previously estimated by various parameterizations of fine-scale structures. This result suggests that these parameterizations are consistent with water mass modifications shown by salinity distributions. Although the estimated diapycnal diffusivity coefficients were the lowest among those used by general circulation models to reproduce tracer distributions, they were closer to directly observed values. Because diapycnal diffusivity was generally small, meridional transports in the upper layers (above about 1600 dbar) associated with diapycnal mixing were relatively small. This result may indicate that diapycnal mixing in coastal regions has relatively large effects on meridional transport, along with water mass formation and mixing and wind forcing at the sea surface. The major water mass transports in subtropical gyres estimated in this study were consistent with previous estimates and corresponded to subduction rates determined using mixed layer thickness budgets and transient tracer inventories. These results, based on recent observation network data, show that understanding of water mass formation and modifications can be improved by taking into account diffusive effects, but more detailed assessments of estimation errors are needed to clarify the role of mixing in water mass modification.

使用长期（2001-2015年）中性密度的长期平均盐度分布（γ）来估算diapycnal，isopycnal和厚度扩散系数的分布）在七个大洋盆地（赤道区域除外）的地表。扩散幅度和空间差异与先前通过精细结构的各种参数化估计的分布一致。该结果表明，这些参数化与盐度分布所显示的水质变化是一致的。尽管估计的总扩散系数在通用循环模型用于再现示踪剂分布的系数中最低，但它们更接近直接观测的值。由于二甲苯的扩散率通常较小，因此与二甲苯混合相关的上层子午传输（约1600 dbar以上）相对较小。这一结果可能表明沿海地区的二叠氮混合对子午线传输有较大影响，以及水团的形成，海面的混合和强迫风。在这项研究中估计的亚热带回旋流的主要水质传输与先前的估计一致，并且对应于使用混合层厚度预算和瞬时示踪物清单确定的俯冲率。这些结果基于最近的观测网络数据显示，可以通过考虑扩散效应来改善对水团形成和修饰的理解，但是需要更详细的估计误差评估以阐明混合在水团修饰中的作用。在这项研究中估计的亚热带回旋流的主要水质传输与先前的估计一致，并且对应于使用混合层厚度预算和瞬时示踪物清单确定的俯冲率。这些结果基于最近的观测网络数据显示，可以通过考虑扩散效应来改善对水团形成和修饰的理解，但是需要更详细的估计误差评估以阐明混合在水团修饰中的作用。在这项研究中估计的亚热带回旋流的主要水质传输与先前的估计一致，并且对应于使用混合层厚度预算和瞬时示踪物清单确定的俯冲率。这些结果基于最近的观测网络数据显示，可以通过考虑扩散效应来改善对水团形成和修饰的理解，但是需要更详细的估计误差评估以阐明混合在水团修饰中的作用。