Frontogenesis in a fluid with horizontal density gradients
Frontogenesis in a fluid with horizontal density gradients
复制标题
具有水平密度梯度的流体中的锋生
DOI：
10.1017/s0022112089001072
复制
发表时间：
1989
影响因子：
3.7
通讯作者：
P. Linden
中科院分区：
文献类型：
--
作者：
J. Simpson;P. Linden
描述了在重力作用下对含有水平密度梯度的流体的调节。流体最初是静止的，随着流体的加速，由斜压密度场驱动，计算所产生的运动。两种形式的初始密度分布被认为是。在第一种情况下，初始水平梯度是恒定的。当等密度线向水平方向旋转时，就产生了一个纯粹的水平运动。垂直密度梯度随时间不断增大，而水平密度梯度基本不变。水平速度具有均匀的垂直切变，梯度理查森数在空间中是恒定的，并随时间单调减小到1/2。第二种密度分布由分段恒定梯度组成，梯度沿着垂直等密度线有跳跃。密度是连续的。在这种情况下，锋生预测发生在两个恒定密度梯度区域之间的等密线上，并确定了锋形成的时间尺度。实验室实验证实了这些计算的结果。此外，还进行了锁交换实验，其中水平平均梯度由一系列由垂直门分隔的台阶密度差表示。
The adjustment under gravity of a fluid containing a horizontal density gradient is described.’ The fluid is initially at rest and the resulting motion is calculated as the flow accelerates, driven by the baroclinic density field. Two forms of the initial density distribution are considered. In the first the initial horizontal gradient is constant. A purely horizontal motion develops as the isopycnals rotate towards the horizontal. The vertical density gradient increases continually with time but the horizontal density gradient remains unchanged. The horizontal velocity has a uniform vertical shear, and the gradient Richardson number is constant in space and decreases monotonically with time to ½. The second density distribution consists of a piecewise constant gradient with a jump in the gradient along a vertical isopycnal. The density is continuous. In this case frontogenesis is predicted to occur on the isopycnal between the two constant-density-gradient regions, and the timescale for the formation of a front is determined. Laboratory experiments are reported which confirm the results of these calculations. In addition, lock exchange experiments have been carried out in which the horizontal mean gradient is represented by a series of step density differences separated by vertical gates.