A Study On The Propagation System Of The Antarctic Circumpolar Wave

In this paper, the Sea Level Pressure dataset from European Centre for Meridional Weather Forecast (ECMWF) is used to analyze the wave mode and propagation process of the Antarctic Circumpolar Wave (ACW). The general wave parameter of ACW is derived using a non-linear approximation method to get the solution of ACW. Also, the propagation process of ACW is carefully examined and we give discussions the correlation between ACW propagation and other anomalies as ENSO signals. The data endures from the year 1985 to 2002, while the regions ranges among the whole Southern Hemisphere. The main conclusions of this paper are:Firstly, a 5 order band-pass Butterworth filtering method of 3-7 years is used to get the main information of interannual SLP variability in the Southern Ocean The spectrum analysis proves the availability of this method. The result of this analysis indicates that ACW merely propagate clearly among the year 1985~1994, and the spatial mode of the result is consistent with White's result. Also, during the years with no clear propagations, the main signal appears to be the local oscillation of the Southern Ocean. The result of the interdecadal variability reveals the decadal signal of SLP in the Southern Ocean is prior to that of ENSO signal. Also, the climate-eruption of ACW (the year1974) occurs earlier than the Nino3 signal (the year 1978);Secondly, the result determines a coexistence system of the standing and traveling wave exists during the clear propagation period of ACW. The least-square non-linear approximation evaluation shows that during the 1985~1992, the standing and traveling part gets the similar wave period and wave number, proving their belonging to the same system. Besides getting the general wave parameter of ACW, the theoretical solution of ACW is also derived at the first time and the result correlates exactly well with the real wave mode, which could well represent the wave mode of ACW. The standing and traveling part of ACW is a coexistence system which get the same frequency and wave speed, and are all important part of ACW dynamical integrals;Thirdly, the spatial propagation process of ACW is given and analyzed. The results shows that ENSO scale process clearly interacts with the propagation process of ACW, which is the disturbance origin of ACW: The traveling wave looks permanent in the Pacific Ocean but is weaker in the Atlantic, and in the Southern Indian Ocean the standing wave is dominant, which is the local oscillation. The three parts possess the same wave period proves that they belongs to the same dynamical process and the coexistence system can be used to represent spatial and temporal character of ACW clearly;Fourthly and lastly, the spatial-departed Empirical Orthogonal Function (EOF) is used to analyze the time-series of SLP to study the propagation process. The result shows that this method can definitely be used to show the propagation process of a wave mode via comparing their time-series of their principal components. The result again proves that there are Indian Ocean standing wave and the traveling wave in the Pacific and Atlantic. Also, the propagation speed among these parts is discussed carefully.