On the Connection between Dense Water Formation, Overturning, and Poleward Heat Transport in a Convective Basin*
On the Connection between Dense Water Formation, Overturning, and Poleward Heat Transport in a Convective Basin*
复制标题
对流盆地中密水形成、翻转和向极传热之间的联系*
DOI：
--
复制
发表时间：
2006
期刊：
影响因子：
--
通讯作者：
F. Straneo
中科院分区：
文献类型：
--
作者：
F. Straneo
本文提出了一个等密度的、两层的、理想化的对流盆地模式，它由对流的内部区域和周围的边界流（浮力和风力驱动）组成。参数化的涡旋通量决定了两者之间的交换。为了平衡内部浮力的损失，边界流在环绕盆地流动时变得更密集。地转强迫这种致密化伴随着边界流的下沉，因此伴随着翻转环流。因此，与海盆中的对流有关的向极地的热输送可以看作是翻转和水平环流的结果。当适应拉布拉多海，该模型是能够再现的平均状态，季节性周期，甚至关闭的对流从1969年至1972年的批量功能。根据该模型，只有40%的极热量（浮力）输送的拉布拉多海与翻转环流。当边界电流的变化很小时，线性化方程的精确解。数值解计算的对流量的变化和远程强迫环流盆地周围的变化。这些结果突出了翻转环流不仅仅与形成的稠密水的数量有关。例如，由于风的强迫，盆地周围的环流加速，将降低翻转环流的强度，而稠密的水的形成保持不变。在一般情况下，它表明，极浮力（或热）运输的翻转环流所携带的部分是不是一个固有的属性的盆地，但可以改变作为一个结果的一些因素。
An isopycnal, two-layer, idealized model for a convective basin is proposed, consisting of a convecting, interior region and a surrounding boundary current (buoyancy and wind-driven). Parameterized eddy fluxes govern the exchange between the two. To balance the interior buoyancy loss, the boundary current becomes denser as it flows around the basin. Geostrophy imposes that this densification be accompanied by sinking in the boundary current and hence by an overturning circulation. The poleward heat transport, associated with convection in the basin, can thus be viewed as a result of both an overturning and a horizontal circulation. When adapted to the Labrador Sea, the model is able to reproduce the bulk features of the mean state, the seasonal cycle, and even the shutdown of convection from 1969 to 1972. According to the model, only 40% of the poleward heat (buoyancy) transport of the Labrador Sea is associated with the overturning circulation. An exact solution is presented for the linearized equations when changes in the boundary current are small. Numerical solutions are calculated for variations in the amount of convection and for changes in the remotely forced circulation around the basin. These results highlight how the overturning circulation is not simply related to the amount of dense water formed. A speeding up of the circulation around the basin due to wind forcing, for example, will decrease the intensity of the overturning circulation while the dense water formation remains unvaried. In general, it is shown that the fraction of poleward buoyancy (or heat) transport carried by the overturning circulation is not an intrinsic property of the basin but can vary as a result of a number of factors.