The low-frequency variance of the ocean surface wave field in the area of the Antarctic Circumpolar Current
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The low-frequency variance of the ocean surface wave field in the area of the Antarctic Circumpolar Current ZHANG Xiaoshuang1,2 , WU Kejian1,3∗ , WANG Bin1 , WANG Zhifeng1 1
Ocean University of China, Qingdao 266100, China Key Laboratory of Marine Environmental Information Technology, National Marine Data and Information Service, State Oceanic Administration, Tianjin 300171, China 3 Physical Oceanography Laboratory, Ocean University of China, Qingdao 266100, China 2
Received 2 August 2011; accepted 3 May 2012 ©The Chinese Society of Oceanography and Springer-Verlag Berlin Heidelberg 2013
Abstract The low-frequency variance of the surface wave in the area of the Antarctic Circumpolar Current (ACC) and its correlation with the antarctic circumpolar wave (ACW) are focused on. The analysis of the series of 44 a significant wave height (SWH) interannual anomalies reveals that the SWH anomalies have a strong periodicity of about 4–5 a and this signal propagates eastward obviously from 1985 to 1995, which needs about 8 a to complete a mimacircle around the earth. The method of empirical orthogonal function (EOF) is used to analyze the filtered monthly SWH anomalies to study the spatio-temporal distributions and the propagation characteristics of the low-frequency signals in the wave field. Both the dominant wavenumber2 pattern in space and the propagation feature in the south Pacific, the south Atlantic and the south Indian ocean show strong consistency with the ACW. So it is reasonable to conclude that the ACW signal also exists in the wave field. The ACW is important for the climate in the Southern Ocean, so it is worth to pay more attention to the large-scale effect of the surface wave, which may also be important for climate studies. Key words: significant wave height, antarctic circumpolar wave, empirical orthogonal function, low-frequency variance Citation: Zhang Xiaoshuang, Wu Kejian, Wang Bin, Wang Zhifeng. 2013. The low-frequency variance of the ocean surface wave field in the area of the Antarctic Circumpolar Current. Acta Oceanologica Sinica, 32(5): 15–21, doi: 10.1007/s13131-013-0309-1
1 Introduction The Southern Ocean is the only ocean that encircles the globe and there is a strong eastward flow in the ocean the Antarctic Circumpolar Current (ACC). The ACC transports the oceanic anomalies through three major ocean basins: the Pacific, the Atlantic and the Indian Ocean. The hemispheric and regional atmospheric circulation can influence the Southern Ocean in many and profound ways, including intense air-sea fluxes of momentum, energy, fresh water and dissolved gases. The Southern Ocean ventilates a large fraction of the world ocean and hence these influences are spread globally (Simmonds, 2004). The interannual and decadal-scale variabilities at the southern high latitudes may affect the global climate by altering the equator-to-pole temperature gradient, that contribute to controlling the atmosphere and ocean dynamics. So the Southern Ocean plays an important role in the worldwide climate anomalies transmi
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