南极绕极波的行波与驻波共存系统分析

ANALYZING THE ANTARCTIC CIRCUMPOLAR WAVE MODE-A COEXISTENCE SYSTEM OF STANDING AND TRAVELING WAVE

南极绕极波(ACW)是近10年来海洋和大气科学领域研究的重要内容之一,其特征表现为一种海气耦合的年际信号在南大洋的明显东向传播。文中依据波动的基本原理,利用非线性拟合方法得到了绕极波行波的平均波速、波数和角频率和印度洋驻波的表达形式,得出行波和驻波具有相同的角频率。针对绕极波纬圈传播的不连续现象,提出了南极绕极波是行波和驻波共存系统的新见解。行波与驻波共存系统由三部分组成:在南大洋的太平洋西侧发生SLP振动,与发生在太平洋中低纬度的过程有关;在太平洋和大西洋存在传播的行波,行波在太平洋最强,到大西洋明显减弱;在印度洋SLP系统表现为局地变化,体现明显的驻波特征。三部分有共同的周期,表明三部分是统一的动力学系统,证实了行波与驻波共存系统可以很好地表达南极绕极波的时空特性和传播特征。

The Antarctic circumpolar wave （ACW） has become a focus of the air-sea coupled Southern Ocean study since 1996, when it was discovered as an air-sea coupled interannual signal propagating eastward in the region of the Antarctic Circumpolar Current （ACC）. In order to analyze the mechanism of discontinuity along the latitudinal propagation, a new idea that ACW is a system with a traveling wave in the Southern Pacific and Atlantic Ocean and with a concurrent standing wave in the southern Indian Ocean is proposed in this paper. Based on the ideal wave principle, we retrieve the average wave parameters of ACW using a non-linear approximation method, where we find that the standing part and the traveling part possess similar radius frequency, proving their belonging to an integral system. We also give the latitudinal distribution of wave speed from what we could tell the reason for steady propagation during that period. The spatial distribution of the propagation reveals complex process with variant spatial and temporal scales the ENSO scale oscillation greatly impacts on the traveling process, while the result south of Australia indicates little connection between the Indian Ocean and the Pacific, which may be blocked by the vibration west of Pacific. The advective effect of ACC on the propagation process should be examined clearly through dynamical method.