A study of Indian Ocean Subtropical Mode Water: subduction rate and water characteristics
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摘要: 通过分析1950-2008年的SODA资料对印度洋区域的潜沉率进行了计算。在副热带西南印度洋区域,以位势密度为函数的潜沉率峰值对应着印度洋副热带模态水的密度分布区间。在副热带模态水生成区,潜沉率主要是由深的混合层,强大的混合层锋面以及相对快速的流场组合所产生的强的侧向导入项控制的,而垂直抽吸项对潜沉率贡献较小。为了不失一般性,根据对垂向温度梯度极小值所在层的水体性质进行细致分析,我们认为印度洋副热模态水是温度均一的巨大水体,且具有较小的位势涡度(<200 10-12 m-1s-1)以及弱的垂向温度梯度(< 1.5 ℃/100米)。印度洋副热带模态水大致分布在印度洋副热带区域:东经25°-50°,南纬30°-39°。此外,我们计算了最近60年左右印度洋副热带模态水气候态平均性质:温度(16.38 0.29, 盐度(35.46±0.04), 位势密度(26.02±0.04) σθ。Abstract: The annual subduction rate in the South Indian Ocean was calculated by analyzing Simple Ocean Data Assimilation (SODA) outputs in the period of 1950-2008. The subduction rate census for potential density classes showed a peak corresponding to Indian Ocean subtropical mode water (IOSTMW) in the southwestern part of the South Indian Ocean subtropical gyre. The deeper mixed layer depth, the sharper mixed-layer fronts and the associated relatively faster circulation in the present climatology resulted in a larger lateral induction, which primarily dominants the IOSTMW subduction rate, while with only minor contribution from vertical pumping. Without loss of generality, through careful analysis of the water characteristics in the layer of minimum vertical temperature gradient (LMVTG), the authors suggest that the IOSTMW was identified as a thermostad, with a lateral minimum of low potential vorticity (PV, less than 200×10-12 m-1·s-1) and a low dT/dz (less than 1.5°C/(100 m)). The IOSTMW within the South Indian Ocean subtropical gyre distributed in the region approximately from 25° to 50° E and from 30° to 39°S. Additionally, the average characteristics (temperature, salinity, potential density) of the mode water were estimated about (16.38 ± 0.29)°C, (35.46 ± 0.04), (26.02 ± 0.04) σθ over the past 60 years.
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Aoki S, Hariyama M, Mitsudera H, et al. 2007. Formation regions of Subantarctic Mode Water detected by OFES and Argo profiling floats. Geophys Res Lett, 34(10): L10606 Bingham F M. 1992. Formation and spreading of Subtropical Mode Water in the North Pacific. J Geophys Res, 97(C7): 11177-11189 Cai Wenju, Santoso A, Wang Guojian, et al. 2014. Increased frequency of extreme Indian Ocean Dipole events due to greenhouse warming. Nature, 510(7504): 254-258 Downes S M, Bindoff N L, Rintoul S R. 2009. Impacts of climate change on the subduction of mode and intermediate water masses in the Southern Ocean. J Climate, 22(12): 3289-3302 Fine R A. 1993. Circulation of Antarctic intermediate water in the South Indian Ocean. Deep-Sea Research Part I: Oceanographic Research Papers, 40(10): 2021-2042 Gu Daifang, Philander S G H. 1997. Interdecadal climate fluctuations that depend on exchanges between the tropics and extratropics. Science, 275(5301): 805-807 Hanawa K. 1987. Interannual variations of the winter-time outcrop area of subtropical mode water in the Western North Pacific Ocean. Atmosphere-Ocean, 25(4): 358-374 Hanawa K, Talley L D. 2001. Mode waters, in ocean circulation and climate. In: Siedler G, Griffies S M, Gould J, et al., eds. International Geophysics Series. Waltham, USA: Academy Press, 77:373-386 Huang Ruixin, Qiu Bo. 1998. The structure of the wind-driven circulation in the subtropical South Pacific Ocean. J Phys Oceanogr, 28(6): 1173-1186 Iselin C O'D. 1939. The influence of vertical and lateral turbulence on the characteristics of the waters at mid-depths. Trans Amer Geophys Union, 20(3): 414-417 Jenkins W J. 1982. On the climate of a subtropical ocean gyre: Decade timescale variations in water mass renewal in the Sargasso Sea. J Mar Res, 40 (Suppl): 265-290 Josey S A, Kent E C, Taylor P K. 1999. New insights into the ocean heat budget closure problem from analysis of the SOC air-sea flux climatology. J Climate, 12(9): 2856-2880 Karstensen J, Quadfasel D. 2002. Formation of southern hemisphere thermocline waters: Water mass conversion and subduction. J Phys Oceanogr, 32(11): 3020-3038 Kobayashi T, Suga T. 2006. The Indian Ocean HydroBase: A highquality climatological dataset for the Indian Ocean. Prog Oceanogr, 68(1): 75-114 Koch-Larrouy A, Morrow R, Penduff T, et al. 2010. Origin and mechanism of subantarctic mode water formation and transformation in the southern indian ocean. Ocean Dynamics, 60(3): 563-583 Lu Peng, McCreary Jr J P, Klinger B A. 1998. Meridional circulation cells and the source waters of the Pacific equatorial undercurrent. J Phys Oceanogr, 28(1): 62-84 Marshall J C, Williams R G, Nurser A J G. 1993. Inferring the subduction rate and period over the North Atlantic. J Phys Oceanogr, 23(7): 1315-1329 Masuzawa J. 1969. Subtropical mode water. Deep-Sea Research and Oceanographic Abstracts, 16(5): 463-472 Maze G, Forget G, Buckley M, et al. 2009. Using transformation and formation maps to study the role of air-sea heat fluxes in North Atlantic Eighteen Degree Water formation. J Phys Oceanogr, 39(8): 1818-1835 McCartney M S. 1982. The subtropical recirculation of mode waters. J Mar Res, 40(Supp): 427-464 McDonagh E L, Bryden H L, King B A, et al. 2005. Decadal changes in the south Indian Ocean thermocline. J Climate, 18(10): 1575-1590 Metzl N, Tilbrook B, Poisson A. 1999. The annual fCO2 cycle and the air-sea CO2 flux in the sub-Antarctic Ocean. Tellus B, 51(4): 849-861 Miyama T, McCreary Jr J P, Jensen T G, et al. 2003. Structure and dynamics of the Indian-Ocean cross-equatorial cell. Deep Sea Research Part II: Topical Studies in Oceanography, 50(12-13): 2023-2047 Olson D B, Fine R A, Gordon A L. 1992. Convective modifications of water masses in the Agulhas. Deep-Sea Research Part A. Oceanographic Research Papers, 39(Supp 1): S163-S181 Poisson A, Metzl N, Brunet C, et al. 1993. Variability of sources and sinks of CO2 in the Western Indian and Southern Oceans during 1991. J Geophys Res, 98(C12): 22759-22778 Qiu Bo, Huang Ruixin. 1995. Ventilation of the North Atlantic and North Pacific: Subduction versus obduction. J Phys Oceanogr, 25(10): 2374-2390 Qu Tangdong, Chen Ju. 2009. A North Pacific decadal variability in subduction rate. Geophys Res Lett, 36(22): L22602 Qu Tangdong, Xie Shangping, Mitsudera H, et al. 2002. Subduction of the North Pacific mode waters in a global high-resolution GCM. J Phys Oceanogr, 32(3): 746-763 Roemmich D, Cornuelle B. 1992. The subtropical mode waters of the South Pacific Ocean. J Phys Oceanogr, 22(10): 1178- 1187 Sabine Christopher L, Richard A Feely, Nicolas Gruber, et al. 2004. The oceanic sink for anthropogenic CO2. Science, 305(5082): 367-371 Saenko O A, Yang Xiaoyi, England M H, et al. 2011. Subduction and transport in the Indian and Pacific Oceans in a 2 climate. J Climate, 24(6): 1821-1838 Sallée J B, Wienders N, Speer K, et al. 2006. Formation of subantarctic mode water in the southeastern Indian Ocean. Ocean Dynamics, 56(5-6): 525-542 Sarmiento J L. 1983. A tritium box model of the North Atlantic thermocline. J Phys Oceanogr, 13(7): 1269-1274 Schneider N, Miller A J, Alexander M A, et al. 1999. Subduction of decadal North Pacific temperature anomalies: Observations and dynamics. J Phys Oceanogr, 29(5): 1056-1070 Schott F A, Dengler M, Schoenefeldt R. 2002. The shallow overturning circulation of the Indian Ocean. Progress in Oceanography, 53(1): 57-103 Smith R D, Dukowicz J K, Malone R C. 1992. Parallel ocean general circulation modeling. Physica D: Nonlinear Phenomena, 60(1-4): 38-61 Stommel H M. 1979. Determination of water mass properties of water pumped down from the Ekman layer to the geostrophic flow below. Proc Natl Acad Sci U S A, 76(7): 3051-3055 Stramma L, Lutjeharms J R E. 1997. The flow field of the subtropical gyre of the South Indian Ocean. J Geophys Res, 102(C3): 5513-5530 Talley L D, Raymer M E. 1982. Eighteen degree water variability. J Mar Res, 40(Supp): 757-775 Toole J M, Warren B A. 1993. A hydrographic section across the subtropical South Indian Ocean. Deep-Sea Research Part I: Oceanographic Research Papers, 40(10): 1973-2019 Tsubouchi T, Suga T, Hanawa K. 2010. Indian Ocean Subtropical Mode Water: its water characteristics and spatial distribution. Ocean Science, 6(1): 41-50 Warren B A. 1972. Insensitivity of subtropical mode water characteristics to meteorological fluctuations. Deep-Sea Research and Oceanographic Abstracts, 19(1): 1-19 Williams R G. 1989. The influence of air-sea interaction on the ventilated thermocline. J Phys Oceanogr, 19(9): 1255-1267 Wong A P S. 2005. Subantarctic Mode Water and Antarctic Intermediate Water in the South Indian Ocean based on profiling float data 2000-2004. J Mar Res, 63(4): 789-812 Woods J D. 1985. The physics of thermocline ventilation. Elsevier Oceanography Series, 40: 543-590 Worthington L V. 1959. The 18 water in the Sargasso Sea. Deep-Sea Research, 5(2-4): 297-305 Worthington L V. 1976. On the North Atlantic Circulation. Baltimore: The Johns Hopkins University Press, 110 Yasuda T, Hanawa K. 1997. Decadal changes in the mode waters in the midlatitude North Pacific. J Phys Oceanogr, 27(6): 858-870
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