热带扰动在大尺度经圈中的行为

The behavior of tropical disturbance in large-scale meridional flow

在赤道β平面上经圈流的背景流场内,利用等值浅水模式来分析波动的不稳定性.结果显示,在经圈半地转假设下,扰动信号通过变性的Rossby波来传递.对于大洋西部,由于向极地方向经圈流的引入,赤道对称的扰动模态对所有的波数k都是不稳定的.对于大洋东部的向赤道流,对赤道对称的扰动却是稳定的.由于一般来讲,扰动倾向于对赤道对称,因此西边界的向极流,如黑潮,比东边界的向赤道流,如加尼福尼亚洋流,更易因扰动的不稳定而产生涡旋.

In the meridional flow on the equatorial β plane,the instability is investigated with an equivalent shallow water model. Under the hypothesis of meridional semi-geostrophy, the disturbance signals propagate in metamorphic Rossby wave. In the polar-ward meridional flow on the west side of the ocean, the disturbance, which is symmetric to the equator, is unstable for any given wave number k. In the equator-ward meridional flow on the east side of the ocean, the disturbance symmetric to the equator is stable. Generally, the disturbance is usually symmetric to the equator. Therefore the polar-ward flow, such as Kuroshio, is easier to generate eddies due to the instability of disturbance than the equator-ward flow such as California current.