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首页> 外文期刊>Journal of Physical Oceanography >Three-Dimensional Ageostrophic Motion in Mesoscale Vortex Dipoles
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Three-Dimensional Ageostrophic Motion in Mesoscale Vortex Dipoles

机译：中尺度涡旋偶极子中的三维年龄营养运动

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The three-dimensional motion of mesoscale baroclinic dipoles is simulated using a nonhydrostatic Bouss-inesq numerical model. The initial conditions are two ellipsoidal vortices of positive and negative potential vorticity anomalies. The flow is moderately ageostrophic with a maximum absolute Rossby number equal to 0.71. The trajectory of the dipole is related to the maximum potential vorticity anomaly and size of the vortices. Three cases are considered depending on the curvature of the dipole trajectory: negative, close to zero, and positive. The ageostrophic flow strongly depends on the distance between the ellipsoidal vortices d_0. For small d_0 the vortices move steadily as a compact dipole, and the vertical velocity w has an octupolar three-dimensional pattern. The horizontal ageostrophic velocity is due to the advective acceleration of the flow, particularly the centripetal acceleration. The speed acceleration is only relatively important at the rear and front parts of the dipole axis, where the flow curvature is small but where the flow confluence and diffluence are, respectively, large. The geostrophy is maximal at the dipole center, on the dipole axis, where both curvature and speed acceleration are minimal. As d_0 increases, the dipole self-propagating velocity and the extreme values of |w| decrease, and vortex oscillations highly distort the octupolar pattern of w. In all cases, as is typical of balanced mesoscale geophysical flows, the vertical velocity is related to the advection of vertical vorticity by the horizontal shear velocity u_(hz) · ▽_hξ.
机译：使用非静力学的Bouss-inesq数值模型模拟了中尺度斜压偶极子的三维运动。初始条件是正和负潜在涡度异常的两个椭圆形涡旋。血流呈中等年龄变质，最大绝对Rossby值等于0.71。偶极子的轨迹与最大潜在涡度异常和涡旋的大小有关。根据偶极子轨迹的曲率考虑三种情况：负，接近零和正。变浆流在很大程度上取决于椭圆形涡旋d_0之间的距离。对于小d_0，涡旋像紧凑的偶极子一样稳定地运动，并且垂直速度w具有八极三维模式。水平的变质速度是由于流动的对流加速度，特别是向心加速度。速度加速度仅在偶极轴的后部和前部相对重要，在偶极轴的后部和前部，流动曲率较小，但流动汇合和扩散分别较大。在偶极轴的偶极中心，曲率和速度加速度都最小，地球物理最大。随着d_0的增加，偶极子的自传播速度和| w |的极值。减小，并且涡旋振荡极大地扭曲了w的八极模式。在所有情况下，如平衡的中尺度地球物理流所代表的那样，垂直速度与水平涡流的平流速度u_（hz）·▽_hξ有关。

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