Influence of two inlets of the Luzon overflow on the deep circulation in the northern South China Sea
-
Abstract: An inverse reduced-gravity model is used to simulate the deep South China Sea (SCS) circulation. A set of experiments are conducted using this model to study the influence of the Luzon overflow through the two inlets on the deep circulation in the northern SCS. Model results suggest that the relative contribution of these inlets largely depends on the magnitude of the input transport of the overflow, but the northern inlet is more efficient than the southern inlet in driving the deep circulation in the northern SCS. When all of the Luzon overflow occurs through the northern inlet the deep circulation in the northern SCS is enhanced. Conversely, when all of the Luzon overflow occurs through the southern inlet the circulation in the northern SCS is weakened. A Lagrangian trajectory model is also developed and applied to these cases. The Lagrangian results indicate that the location of the Luzon overflow likely has impacts upon the sediment transport into the northern SCS.
-
Key words:
- inlets /
- Luzon overflow /
- deep circulation /
- northern South China Sea
-
Figure 1. Bottom topography (color shading) of the SCS and the vertically-averaged geostrophic current (vector) from 2 400 m to the bottom derived from U.S. Navy Generalized Digital Environment Model (GDEM) Version 3.0 (a), and bottom topography (color shading, m) and the schematic flow (red vector lines) across the Luzon Strait with N and S indicating the northern and southern inlets of the Luzon overflow (b). The red dot in a indicates the mooring location used in this study.
Figure 2. Geostrophic current speed below 2 400 m at 18°N in the SCS calculated from GDEM assuming a depth of no motion at 2 400 m.
Figure 3. Horizontal velocity time series (a) and its temporal average (b) at M1 mooring.
Figure 4. The abyssal circulation (vectors) and current speed (color shading) for the control case (CTRL).
Figure 5. The mean current speed between 17.5°–19.5°N along meridional section (a) and the mean current speed between 114°–116°E along the zonal section (b) from the CTRL case (black lines) and GDEM (black dashed lines).
Figure 6. The abyssal circulation from Case-N1 (a) and Case-S1 (b), the abyssal circulation anomalies for Case-N1 plus Case-S1 minus CTRL (c), and the mean current speed between 17.5°–19.5°N along meridional section from the CTRL (black solid line), Case-N1 (black solid line with northward triangle), and Case-S1 (black solid line with southward triangle) (d).
Figure 7. The abyssal circulation anomalies for Case-N2 (a) and Case-S2 (b). The schematic diagram at the lower right indicates the general source-sink circulation pattern. Compared to the CTRL, the forcing in the Case-N2 is a 0.9×106 m3/s source at the northern inlet and a 0.9×106 m3/s sink at the southern inlet; while for the Case-S2, there is a 0.7×106 m3/s sink at the northern inlet and a 0.7×106 m3/s source at the southern inlet.
Figure 8. The mean current speed between 17.5°–19.5°N along meridional section (a) and the mean current speed between 114°–116°E along the zonal section (b) from the CTRL case (black lines), Case-N2 (red line), and Case-S2 (blue line).
Figure 9. The trajectories of five tracer parcels in the CTRL (a), Case-N2 (b) and Case-S2 (c). The black arrows denote the abyssal circulation.
Table 1. Details of the numerical experiment
Case Overflow Other settings CTRL 1.6×106 m3/s, 0.7×106 m3/s from northern inlet
and 0.7×106 m3/s southern inletβ-plain, uniform upwelling and with bottom topography Case-N1 only 0.7×106 m3/s, all from northern inlet Case-S1 only 0.9×106 m3/s, all from southern inlet Case-N2 1.6×106 m3/s, all from northern inlet Case-S2 1.6×106 m3/s, all from southern inlet 
下载: 导出CSV
-
[1] Carnes M R. 2009. Description and Evaluation of GDEM-V3.0. Naval Research Laboratory (NRL) Report NRL/MR/7330-09-9165. Washington, DC: Naval Research Laboratory [2] Chang Y T, Hsu W L, Tai J H, et al. 2010. Cold deep water in the South China Sea. Journal of Oceanography, 66(2): 183–190. doi: 10.1007/s10872-010-0016-x [3] Döös K, Kjellsson J, Jönsson B. 2013. TRACMASS—A Lagrangian trajectory model. In: Soomere T, Quak E, eds. Preventive Methods for Coastal Protection. Heidelberg: Springer, 225–249 [4] Garabato A C N, Polzin K L, King B A, et al. 2004. Widespread intense turbulent mixing in the southern ocean. Science, 303(5655): 210–213. doi: 10.1126/science.1090929 [5] Godin G. 1966. Daily mean sea level and short-period seiches. International Hydrographic Review, 43(2): 75–89 [6] Heywood K J, Garabato A C, Stevens D P. 2002. High mixing rates in the abyssal Southern Ocean. Nature, 415(6875): 1011–1014. doi: 10.1038/4151011a [7] Kunze E, Sanford T B. 1996. Abyssal mixing: Where it is not. Journal of Physical Oceanography, 26(10): 2286–2296. doi: 10.1175/1520-0485(1996)026<2286:AMWIIN>2.0.CO;2 [8] Lan Jian, Wang Yu, Cui Fengjuan, et al. 2015. Seasonal variation in the South China Sea deep circulation. Journal of Geophysical Research: Oceans, 120(3): 1682–1690. doi: 10.1002/2014JC010413 [9] Lan Jian, Zhang Ningning, Wang Yu. 2013. On the dynamics of the South China Sea deep circulation. Journal of Geophysical Research: Oceans, 118(3): 1206–1210. doi: 10.1002/jgrc.20104 [10] Ledwell J R, Montgomery E T, Polzin K L, et al. 2000. Evidence for enhanced mixing over rough topography in the abyssal ocean. Nature, 403(6766): 179–182. doi: 10.1038/35003164 [11] Li Li, Qu Tangdong. 2006. Thermohaline circulation in the deep South China Sea basin inferred from oxygen distributions. Journal of Geophysical Research, 111: C05017 [12] Liu C T, Liu R J. 1988. The deep current in the Bashi Channel. Acta Oceanographica Taiwanica, 20: 107–116 [13] Liu Zhifei, Stattegger K. 2014. South China Sea fluvial sediments: An introduction. Journal of Asian Earth Sciences, 79: 507–508. doi: 10.1016/j.jseaes.2013.11.003 [14] Mauritzen C, Polzin K L, McCartney M S, et al. 2002. Evidence in hydrography and density fine structure for enhanced vertical mixing over the Mid-Atlantic Ridge in the western Atlantic. Journal of Geophysical Research, 107(C10): 3147. doi: 10.1029/2001JC001114 [15] Qu Tangdong. 2002. Evidence for water exchange between the South China Sea and the Pacific Ocean through the Luzon Strait. Acta Oceanologica Sinica, 21(2): 175–185 [16] Qu Tangdong, Girton J B, Whitehead J A. 2006. Deepwater overflow through Luzon Strait. Journal of Geophysical Research: Oceans, 111: C01002 [17] Shao Lei, Li Xuejie, Geng Jianhua, et al. 2007. Deep water bottom current deposition in the northern South China Sea. Science in China Series D: Earth Sciences, 50(7): 1060–1066. doi: 10.1007/s11430-007-0015-y [18] Shu Yeqiang, Xue Huijie, Wang Dongxiao, et al. 2014. Meridional overturning circulation in the South China Sea envisioned from the high-resolution global reanalysis data GLBa0.08. Journal of Geophysical Research: Oceans, 119(5): 3012–3028. doi: 10.1002/2013JC009583 [19] Shu Yeqiang, Xue Huijie, Wang Dongxiao, et al. 2016. Persistent and energetic bottom-trapped topographic Rossby waves observed in the southern South China Sea. Scientific Reports, 6: 24338. doi: 10.1038/srep24338 [20] Speer K, Tziperman E, Feliks Y. 1993. Topography and grounding in a simple bottom layer model. Journal of Geophysical Research, 98(C5): 8547–8558. doi: 10.1029/92JC03018 [21] St Laurent L, Garrett C. 2002. The role of internal tides in mixing the deep ocean. Journal of Physical Oceanography, 32(10): 2882–2899. doi: 10.1175/1520-0485(2002)032<2882:TROITI>2.0.CO;2 [22] Stommel H, Arons A B. 1959–1960a. On the abyssal circulation of the World Ocean-I. Stationary planetary flow patterns on a sphere. Deep Sea Research, 6: 140–154. doi: 10.1016/0146-6313(59)90065-6 [23] Stommel H, Arons A B. 1959–1960b. On the abyssal circulation of the World Ocean-II. An idealized model of the circulation pattern and amplitude in oceanic basins. Deep Sea Research, 6: 217–233. doi: 10.1016/0146-6313(59)90075-9 [24] Stommel H, Arons A B, Faller A J. 1958. Some examples of stationary planetary flow patterns in bounded basins. Tellus, 10(2): 179–187. doi: 10.3402/tellusa.v10i2.9238 [25] Tian Jiwei, Qu Tangdong. 2012. Advances in research on the deep South China Sea circulation. Chinese Science Bulletin, 57(24): 3115–3120. doi: 10.1007/s11434-012-5269-x [26] Tian Jiwei, Yang Qiangxuan, Liang Xinfeng, et al. 2006. Observation of Luzon Strait transport. Geophysical Research Letters, 33(19): L19607. doi: 10.1029/2006GL026272 [27] Tian Jiwei, Yang Qingxuan, Zhao Wei. 2009. Enhanced Diapycnal Mixing in the South China Sea. Journal of Physical Oceanography, 39(12): 3191. doi: 10.1175/2009JPO3899.1 [28] Wang Aimei, Du Yan, Peng Shiqiu, et al. 2018. Deep water characteristics and circulation in the South China Sea. Deep Sea Research Part I: Oceanographic Research Papers, 134: 55–63. doi: 10.1016/j.dsr.2018.02.003 [29] Wang Dongxiao, Wang Qiang, Cai Shuqun, et al. 2019. Advances in research of the mid-deep South China Sea circulation. Science China Earth Sciences, 62(12): 1992–2004. doi: 10.1007/s11430-019-9546-3 [30] Wang Dongxiao, Xiao Jingen, Shu Yeqiang, et al. 2016. Progress on deep circulation and meridional overturning circulation in the South China Sea. Science China Earth Sciences, 59(9): 1827–1833. doi: 10.1007/s11430-016-5324-6 [31] Wang Guihua, Xie Shangping, Qu Tangdong, et al. 2011. Deep South China Sea circulation. Geophysical Research Letters, 38(5): L05601 [32] Wang J. 1986. Observation of abyssal flows in the northern South China Sea. Acta Oceanographica Taiwanica, 16: 36–45 [33] Wyrtki K. 1961. Physical oceanography of the Southeast Asian waters. In: NAGA Report Volume 2, Scientific Results of Marine Investigations of the South China Sea and the Gulf of Thailand. San Diego, California: Scripps Institution of Oceanography [34] Yang Jiayan. 2005. The arctic and subarctic ocean flux of potential vorticity and the arctic ocean circulation. Journal of Physical Oceanography, 35(12): 2387–2407. doi: 10.1175/JPO2819.1 [35] Yang Jiayan, Price J F. 2000. Water-mass formation and potential vorticity balance in an abyssal ocean circulation. Journal of Marine Research, 58(5): 789–808. doi: 10.1357/002224000321358918 [36] Yang Qingxuan, Zhao Wei, Liang Xinfeng, et al. 2016. Three-dimensional distribution of turbulent mixing in the South China Sea. Journal of Physical Oceanography, 46(3): 769–788. doi: 10.1175/JPO-D-14-0220.1 [37] Ye Ruijie, Zhou Chun, Zhao Wei, et al. 2019. Variability in the deep overflow through the Heng-Chun Ridge of the Luzon Strait. Journal of Physical Oceanography, 49(3): 811–825. doi: 10.1175/JPO-D-18-0113.1 [38] Zhang Yanwei, Liu Zhifei, Zhao Yulong, et al. 2014. Mesoscale eddies transport deep-sea sediments. Scientific Reports, 4(1): 5937 [39] Zhang Zhiwei, Zhao Wei, Tian Jiwei, et al. 2015. Spatial structure and temporal variability of the zonal flow in the Luzon Strait. Journal of Geophysical Research: Oceans, 120(2): 759–776. doi: 10.1002/2014JC010308 [40] Zhao Wei, Zhou Chun, Tian Jiwei, et al. 2014. Deep water circulation in the Luzon Strait. Journal of Geophysical Research: Oceans, 119(2): 790–804. doi: 10.1002/2013JC009587 [41] Zheng Hongbo, Yan Pin. 2012. Deep-water bottom current research in the Northern South China Sea. Marine Georesources and Geotechnology, 30(2): 122–129. doi: 10.1080/1064119X.2011.586015 [42] Zhou Chun, Zhao Wei, Tian Jiwei, et al. 2014. Variability of the deep-water overflow in the Luzon Strait. Journal of Physical Oceanography, 44(11): 2972–2986. doi: 10.1175/JPO-D-14-0113.1 [43] Zhou Chun, Zhao Wei, Tian Jiwei, et al. 2017. Deep western boundary current in the South China Sea. Scientific Reports, 7(1): 9303. doi: 10.1038/s41598-017-09436-2 -
点击查看大图
计量
- 文章访问数: 392
- HTML全文浏览量: 116
- PDF下载量: 9
- 被引次数: 0
