A numerical study on seasonal variations of the thermocline in the South China Sea based on the ROMS

• Published in: Acta oceanologica Sinica Vol. 33; no. 7; pp. 56 - 64
• Main Authors: Fan, Wei, Song, Jinbao, Li, Shuang
• Format: Journal Article
• Language: English
• Published: Heidelberg The Chinese Society of Oceanography 01.07.2014; Springer Nature B.V; Key Laboratory of 0cean Circulation and Waves, Institute of 0ceanology, Chinese Academy of Sciences, Qingdao 266071, China%Department of 0cean Science and Engineering, Zhejiang University, Hangzhou 310058, China
• Subjects: Bathymetry; Climatology; Cyclones; Earth and Environmental Science; Earth Sciences; Ecology; Engineering Fluid Dynamics; Environmental Chemistry; Fluid mechanics; Hurricanes; Hydrodynamics; Marine & Freshwater Sciences; Monsoons; Ocean circulation; Ocean models; Oceanography; Seasonal variation; Seasonal variations; Shelf seas; Shelving; Summer; Temperature profile; Temperature profiles; Thermocline; Tropical cyclones; Typhoons; Upper bounds; Wind; Winds; Winter; 中国南海; 垂直温度分布; 季节变化; 季节性; 数值研究; 海洋地形; 混合动力; 温跃层; South China Sea; China; ISEW, South China Sea; South China Sea; typhoon; ROMS; thermocline
• ISSN: 0253-505X; 1869-1099
• DOI: 10.1007/s13131-014-0504-8

On the basis of the regional ocean modeling system （ROMS）, the seasonal variations of the thermocline in the South China Sea （SCS） were numerically investigated. The simulated hydrodynamics are in accordance with previous studies： the circulation pattern in the SCS is cyclonic in winter and anticyclonic in summer, and such a change is mostly driven by the monsoon winds. The errors between the modeled temperature profiles and the observations obtained by cruises are quite small in the upper layers of the ocean, indicating that the ocean status is reasonably simulated. On the basis of the shapes of the vertical temperature profiles, five thermocline types （shallow thermocline, deep thermocline, hybrid thermocline, double thermocline, and multiple thermocline） are defined herein. In winter, when the northeasterly monsoon prevails, most shallow shelf seas in the northwest of the SCS are well mixed, and there is no obvious thermocline. The deep region generally has a deep thermocline, and the hybrid or double thermocline often occurs in the areas near the cold eddy in the south of the SCS. In summer, when the southwesterly monsoon prevails, the shelf sea area with a shallow thermocline greatly expands. The distribution of different thermocline types shows a relationship with ocean bathymetry： from shallow to deep waters, the thermocline types generally change from shallow or hybrid to deep thermocline, and the double or multiple thermocline usually occurs in the steep regions. The seasonal variations of the three major thermocline characteristics （the upper bound depth, thickness, and intensity） are also discussed. Since the SCS is also an area where tropical cyclones frequently occur, the response of thermocline to a typhoon process in a short time scale is also analyzed.