Based on the analysis of temperature and salinity survey data in the central South China Sea (SCS) in March2014, we found that there existed a notable low temperature and high salinity water mass in the northern Zhongsha Islands. The core temperature of the water mass was only 25℃ in the surface layer (5 m), which was lower than that at the surrounding stations by at least 1℃, and its core salinity was 34.11 psu, which was higher than that at the surrounding stations by at least 0.74 psu. Furthermore, the water mass had influence on an area of about 1 longitude by 1.5 latitude, just 30 m from the sea surface, and it could last approximately for 13 days. Combining with the topography data, satellite altimeter data and wind data, we demonstrated the forming and decaying processes and dynamic mechanisms of the water mass. In early March, a strong mesoscale cold eddy shed from the Luzon cold eddy system and propagated to the west; it stagnated and deformed when encountering the continental shelf at about 115°E, 18°N. However, under the induction of topography and wind, the southern edge of the strong mesoscale cold eddy shed a small cyclonic eddy again, namely, the low temperature and high salinity water mass that was observed. The water mass propagated to the Zhongsha Islands area around the 3000m isobath. The water mass vanished owing to the wind direction change from the northeasterly on March 29to the southerly at the beginning of April. The southerly wind accelerated the mixing between the southern warm water and the low temperature and high salinity water mass, and then the low temperature and high salinity water mass disappeared at last.
TIAN Yongqing
,
HUANG Honghui
,
GONG Xiuyu
,
YU Shaomei
. The formation mechanism of the low temperature and high salinity water mass near the Zhongsha Islands in the South China Sea in March 2014[J]. Journal of Tropical Oceanography, 2016
, 35(2)
: 1
-9
.
DOI: 10.11978/2014113
[1] 黄企洲, 1983. 巴士海峡黑潮流速和流量的变化[J]. 热带海洋, 2(1): 37–41. HUANG QIZHOU, 1983. Variations of velocity and transport of the Kuroshio in the Bashi Channel[J]. Tropic Oceanology, 2(1): 37–41 (in Chinese).
[2] 姜良红, 胡建宇, 2010. 吕宋冷涡的季节变化特征及其与风应力的关系[J]. 台湾海峡, 29(1): 114–121. JIANG LIANGHONG, HU JIANYU, 2010. Seasonal variability of the Luzon cold eddy and its relation with wind stress[J]. Journal of Oceanography in Taiwan Strait, 29(1): 114–121 (in Chinese).
[3] 李凤岐, 苏育嵩, 1999. 海洋水团分析[M]. 青岛: 青岛海洋大学出版社: 377–378. LI FENGQI, SU YUSONG, 1999. Analyses of Water Masses in Oceans[M]. Qingdao: Qingdao Ocean University Press: 377–378 (in Chinese).
[4] 李立, 吴日升, 郭小钢, 2000. 南海的季节环流——TOPEX/ POSEITON卫星测高应用研究[J]. 海洋学报, 22(6): 13–25. LI LI, WU RISHENG, GUO XIAOGANG, 2000. Seasonal circulation in the South China Sea—A TOPEX/POSEIDON satellite altimetry study[J]. Acta Oceanologica Sinica, 22(6): 13–25 (in Chinese).
[5] 刘长建, 庄伟, 夏华永, 等, 2012. 2009—2010年冬季南海东北部中尺度过程观测[J]. 海洋学报, 34(1): 8–16. LIU CHANGJIAN, ZHUANG WEI, XIA HUAYONG, et al, 2012. Mesoscale observation in the northeast South China Sea during winter 2009-2010[J]. Acta Oceanologica Sinica, 34(1): 8–16 (in Chinese).
[6] 刘金芳, 毛可修, 闫明, 等, 2006. 吕宋冷涡时空特征概况[J]. 海洋预报, 23(2): 39–44. LIU JINFANG, MAO KEXIU, YAN MING, et al, 2006. The general distribution characteristics of thermocline of China Sea[J]. Marine Forecasts, 23(2): 39–44 (in Chinese).
[7] 刘先炳, 苏纪兰, 1992. 南海环流的一个约化模式[J]. 海洋与湖沼, 23(2): 167–174. LIU XIANBING, SU JILAN, 1992. A reduced gravity model of the circulation in the South China Sea[J]. Oceanologia et Limnologia Sinica, 23(2): 167–174 (in Chinese).
[8] 孙成学, 刘秦玉, 2011. 卫星高度计资料揭示的冬季南海吕宋冷涡的双涡结构[J]. 热带海洋学报, 30(3): 9–15. SUN CHENGXUE, LIU QINYU, 2011. Double eddy structure of the winter Luzon Cold Eddy based on satellite altimeter data[J]. Journal of Tropical Oceanography, 30(3): 9–15 (in Chinese).
[9] 王桂华, 苏纪兰, 齐义泉, 2005. 南海中尺度涡研究进展[J]. 地球科学进展, 20(8): 882–886. WANG GUIHUA, SU JILAN, QI YIQUAN, 2005. Advances in studying mesoscale eddies in South China Sea[J]. Advances in Earth Science, 20(8): 882–886 (in Chinese).
[10] 许建平, 苏纪兰, 仇德忠, 1996. 黑潮水入侵南海的水文分析[G]//南海东北部海区环流课题组.中国海洋学文集(6). 北京:海洋出版社: 1–12.
[11] HU JIANYU, KAWAMURA H, HONG HUASHENG, et al, 2000. A review on the currents in the South China Sea: Seasonal circulation, South China Sea Warm Current and Kuroshio intrusion[J]. Journal of Oceanography, 56(6): 607–624.
[12] LI LI, WORTH D N, SU JILAN, 1998. Anticyclonic rings from the Kuroshio in the South China Sea[J]. Deep-Sea Research Part I, 45(9): 1469–1482.
[13] LI LI, POHLMANN T, 2002. The South China Sea warm-core ring 94S and its influence on the distribution of chemical tracers[J]. Ocean Dynamics, 52(3): 116–122.
[14] LI LI, QU TANGDONG, 2006. Thermohaline circulation in the deep South China Sea basin inferred from oxygen distributions[J]. Journal of Geophysical Research, 111(C5): 1–10.
[15] NITANI H, 1972. Beginning of the Kuroshio[M]//STOMMEL H, YOSHIDA K. Kuroshio: Physical aspects of the Japan Current. Seattle: University of Washington Press: 129–163.
[16] NOF D, JIA YINGLAI, CHASSIGNET E, et al, 2011. Fast wind- induced migration of eddies in the South China Sea[J]. Journal of Physical Oceanography, 41: 1683–1693.
[17] QU TANGDONG, 2002. Evidence for water exchange between the South China Sea and the Pacific Ocean through the Luzon Strait[J]. Acta Oceanologica Sinica, 21(2): 175–185.
[18] WYRTKI K, 1961. NAGA Report: Scientific results of marine investigation of the South China Sea and Gulf of Thailand[R]. California: University of California, Scripps Institution of Oceanography: 195.
[19] YANG HAIJUN, LIU QINYU, 2003. Forced Rossby wave in the northern South China Sea[J]. Deep-Sea Research PartⅠ, 50(7): 917?926.
[20] YUAN DONGLIANG, 2002. A numerical study of the South China Sea deep circulation and its relation to the Luzon Strait transport[J]. Acta Oceanologica Sinica, 21(2): 187–202.
