Diagnosing water mass formation from air-sea fluxes and surface mixing
Diagnosing water mass formation from air-sea fluxes and surface mixing
复制标题
DOI：
10.1175/1520-0485(1999)029
复制
发表时间：
1999-07-01
影响因子：
3.5
通讯作者：
Williams, RG
中科院分区：
文献类型：
--
作者：
Nurser, AJG;Marsh, R;Williams, RG
水团的形成率及其与海气通量和内部混合的关系，研究在北（和热带）大西洋，包括一个混合层的等密度模型。诊断遵循Walin的公式。联系体积和潜在的密度预算为isopycnol层。作者认为水的质量生产之间的平衡。在两种极限情况下，模型中的混合和海气通量：（一）没有混合，海气通量直接驱动水火星的形成;（二）封闭盆地中的稳定状态，海气通量通过扩散平衡。在这样一个定常状态下，由于混合总是起着减小密度对比的作用，所以表面强迫必须起着增大密度对比的作用。考虑到整个海盆，包括热带，模式除了密度层外处于定常状态。在热带上升流区，大部分混合是通过强密度梯度中的透壁扩散和热带混合层的卷吸实现的。混合夹带与季节性循环的混合层深度在中高纬度和混合层内的密度的横向混合是不太重要的热带混合。这些模型的结果，不同的混合过程的相对重要性是一致的一个简单的缩放analysis.Outside的热带，上升流连接的混合不再重要，和一阶估计的水团形成率可以从表面通量。混合层内密度的横向混合和季节性的卷吸混合与该区域内的温跃层混合一样重要。在整个区域和对流层外区域诊断出明显的垂直扩散系数。对于密度较大的沃茨，它达到10（4）m（2）s（-1）。大约是温跃层内明显的底膜扩散的四倍。
The formation rate of water masses and its relation to air-sea fluxes and interior mixing are examined in an isopycnic model of the North (and tropical) Atlantic that includes a mixed layer. The diagnostics follow Walin's formulation. linking volume and potential density budgets for an isopycnol layer.The authors consider the balance between water mass production. mixing, and air-sea fluxes in the model in the context of two limit cases: (i) with no mixing, where air-sea fluxes drive water mars formation directly, and (ii) a steady state in a closed basin, where air-sea fluxes are balanced by diffusion. In such a steady state, since mixing always acts to reduce density contrast, surface forcing must act to increase it.Considered over the whole basin, including the Tropics, the model is in steady state apart from the densest layers, Most of the mixing is achieved by diapycnal diffusion in the strong density gradients within upwelling regions in the Tropics, and by entrainment into the tropical mixed layer. Mixing from entrainment associated with the seasonal cycle of mixed layer depth in mid and high latitudes and lateral mixing of density within the mixed laver are less important than this tropical mixing. These model results as to the relative importance of the different mixing processes are consistent with a simple scaling analysis.Outside the Tropics, the upwelling-linked mixing is no longer important, and a first-order estimate of water mass formation rates may be made from the surface fluxes. Lateral mixing of density within the mixed layer and seasonal entrainment mixing are as important as the remaining thermocline mixing within this domain,An apparent vertical diffusivity is diagnosed over both the full and extratropical domain. It reaches 10 (4) m(2) s(-1) for the denser waters. about four times as large as the explicit diapycnal diffusion within the thermocline.