Mesoscale characteristics of Antarctic Intermediate Water in the South Pacific
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摘要: 本文利用ARGO漂流浮标观测资料分析南大洋南极中层水(AAIW)的中尺度特征.研究表明次表层中尺度现象很有可能被在海洋中上下运动的ARGO漂流浮标捕捉到,并且通过垂向温盐剖面中水平的盐度梯度可以辨认出来.南大洋南极中层水输运的过程中可能携带着非常丰富的中尺度特征.为了得到南极中层水中尺度变异的空间尺度、持续时间和传播特性,我们利用基于现场观测的网格化ENACT/ENSEMBLE 3温度-盐度数据,并用经验模分解方法处理平均等密度面上的在26.8-27.4之间的盐度异常,将南极中层水分解成一个海盆尺度模态和两个中尺度模态.经研究发现,南极中层水的第一个中尺度模态的空间尺度是1000km量级,可以解释近50%的中尺度变异.它的西向传播速度在中纬度相对较低,只有1cm/s左右,而在低纬度地区传播速度却很快,接近6cm/s,然而在25°-30°S也出现了快速的增长.第二个中尺度模态的空间尺度在500km量级,能够解释大概30%的南极中层水的中尺度变异.西向传播速度随着纬度变化很小,都在0.5cm/s左右.这些研究结果表明,在大洋次表层中存在更强的湍流作用,同时也说明ARGO计划对于深海研究有着深远的意义.Abstract: The Argo float observations are used to investigate the mesoscale characteristics of the Antarctic Intermediate Water (AAIW) in the South Pacific in this paper. It is shown that a subsurface mesoscale phenomenon is probably touched by an Argo float during the float's ascent-descent cycles and is identified by the horizontal salinity gradient between the vertical temperature-salinity profiles. This shows that the transportation of the AAIW may be accompanied with the rich mesoscale characteristics. To derive the spatial length, time, and propagation characteristics of the mesoscale variability of the AAIW, the gridded temperature-salinity dataset ENACT/ENSEMBLE Version 3 constructed on the in-situ observations in the South Pacific since 2005 is used. The Empirical Mode Decomposition method is applied to decompose the isopycnal-averaged salinity anomaly from 26.8 σθ-27.4 σθ, where the AAIW mainly resides, into the basin scale and two mesoscale modes. It is found that the first mesoscale mode with the length scale on the order of 1 000 km explains nearly 50% variability of the mesoscale characteristics of the AAIW. Its westward-propagation speeds are slower in the mid-latitude (around 1 cm/s) and faster in the low latitude (around 6 cm/s), but with an increasing in the latitude band on 25°-30°S. The second mesoscale mode is of the length scale on the order of 500 km, explaining about 30% variability of the mesoscale characteristics of the AAIW. Its westward-propagation speed keeps nearly unchanged (around 0.5 cm/s). These results presented the stronger turbulent motion of the subsurface ocean on the spatial scale, and also described the significant role of Argo program for the better understanding of the deep ocean.
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Key words:
- mesoscale characteristics /
- subsurface ocean /
- Antarctic Intermediate Water (AAIW) /
- Argo
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Alory H, Wijffels S, Meyers G M. 2007. Observed temperature trends in the Indian Ocean over 1960-1999 and associated mechan-isms. Geophys Res Lett, 34: L02606 Barron C N, Kara A B, Jacobs G A. 2009. Objective estimates of west-ward Rossby wave and eddy propagation from sea surface height analyses. J Geophys Res, 114: C03013 Boyer T P, Antonov J I, Garcia H, et al. 2006. World Ocean Database 2005, Chapter 1: Introduction, NOAA Atlas NESDIS 60. In: Levi-tus S, eds. Washington, D C: US Government Printing Office, 182, DVD Casal T G D, Beal L M, Lumpkin R. 2006. A North Atlantic deep-water eddy in the Agulhas current system. Deep-Sea Res Pt I, 53: 1718-1728 Challenor P G, Cipollini P, Cromwell D. 2001. Use of the 3D Radon transform to examine the properties of oceanic Rossby waves. J Atmos Oceanic Technol, 18(9): 1558-1566 Chelton D B, Schlax M G. 1996. Global observations of oceanic Rossby waves. Science, 272(5259): 234-238 Chelton D B, Schlax M G, Lyman J M, et al. 2003. Equatorially trapped Rossby waves in the presence of meridionally sheared baroclin-ic flow in the Pacific Ocean. Prog Oceanogr, 56(2): 323-380 Chelton D B, Schlax M G, Samelson R M, et al. 2007. Global observa-tions of large oceanic eddies. Geophys Res Lett, 34: L15606 Chiswell S M and Sutton P J H. 1998. A deep eddy in the Antarctic Intermediate Water North of the Chatham rise. J Phys Oceanogr, 28: 535-540 Chen Xianyao, Wu Zhaohua, Huang N E. 2010. The time-dependent intrinsic correlation based on the empirical mode decomposi-tion. Advances in Adaptive Data Analysis, 2(2): 233-265 Cipollini P, Cromwell D, Challenor P G, et al. 2001. Rossby waves de-tected in global ocean colour data. Geophys Res Lett, 28(2): 323-326 Dengler M, Schott F A, Eden C, et al. 2004. Break- up of the Atlantic deep western boundary current into eddies at 81°S. Nature, 432: 1018-1020 Domingues C M, Church J A, White N J, et al. 2008. Improved estim-ates of upper-ocean warming and multi-decadal sea level rise. Nature, 453(7198): 1090-1093 Halliwell G R Jr, Mooers C N K. 1979. The space-time structure and variability of the shelf water-slope water and Gulf Stream sur-face temperature fronts and associated warm-core eddies. J Geophys Res, 84: 7707-7725 Halliwell G R Jr, Ro Y J, Cornillon P. 1991. Westward-propagating SST anomalies and baroclinic eddies in the Sargasso Sea. J Phys Oceanogr, 21: 1664-1680 Hill K L, Robinson I S, Cipollini P. 2000. Propagation characteristics of extratropical planetary waves observed in the ATSR global sea surface temperature record. J Geophys Res, 105(C9): 21927-21945 Huang N E, Shen Zheng, Long S R, et al. 1998. The empirical mode decomposition and the Hilbert spectrum for nonlinear and non-stationary time series analysis. Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences, 454(1971): 903-995 Huang N E, Wu Zhaohua. 2008. A review on Hilbert-Huang trans-form: the method and its applications to geophysical studies. Rev Geophys, 46: RG2006 Huang N E, Wu Zhaohua, Long S R, et al. 2009. On instantaneous fre-quency. Advances in Adaptive Data Analysis, 1(2): 177-229 Isern-Fontanet J, Garcia-Ladona E, Font J. 2003. Identification of marine eddies from altimetric maps. J Atmos Oceanic Technol,20: 772-778 Ingleby B, Huddleston M. 2007. Quality control of ocean temperature and salinity profiles historical and real-time data. Journal of Marine Systems, 65(1-4): 158-175 Jacobs G A, Barron C N, Rhodes R C. 2001. Mesoscale characteristics. J Geophys Res, 106(C9): 19581-19595 McWilliams J C, Owens W B, Hua B L. 1986. An objective analysis of the POLYMODE Local Dynamics Experiment, part I,General formalism and statistical model selection. J Phys Oceanogr, 380(16): 483-504 Naveira Garabato A C, Jullion L, Stevens D P, et al. 2009. Variability of subantarctic mode water and Antarctic intermediate water in the Drake Passage during the Late-Twentieth and Early-Twenty-First centuries. J Climate, 22(13): 3661-3688 Oka E. 2005. Long-term sensor drift found in recovered ARGO profil-ing floats. Journal of Oceanography, 61(4): 775-781 Richardson P L, Bower A S, Zenk W. 2000. A census of meddies tracked by floats. Prog Oceanogr, 45: 209-250 Susanto R D, Zheng Quanan, Yan Xiaohai. 1998. Complex singular value decomposition analysis of equatorial waves in the Pacific observed by TOPEX/Poseidon altimeter. J Atmos Oceanic Technol, 15(3): 764-774 Tomczak M, Andrew C. 1997. Eddy formation in the Antarctic Inter-mediate Water of the subtropical South Pacific Ocean. J Mar At-mos Res, 1: 8-12 Tomczak M. 2006. Variability of Antarctic intermediate water proper-ties in the South Pacific Ocean. Ocean Science Discussions, 3(6): 2021-2058 Weatherly G, Arhan M, Mercier H, et al. 2002. Evidence of abyssal ed-dies in the Brazil Basin. J Geophys Res, 107: 3027-3041 Wu Zhaohua, Huang N E. 2009. Ensemble empirical mode decom-position: A noise-assisted data analysis method. Advances in Adaptive Data Analysis, 1(1): 1-41 Wu Zhaohua, Huang N E, Long S R, et al. 2007. On the trend, detrend-ing, and variability of nonlinear and nonstationary time series. Proceedings of the National Academy of Sciences of the United States of America, 104(38): 14889-14894
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