南海中部海域夏季水团温盐分布特征

TEMPERATURE AND SALINITY STRUCTURES OF THE CENTRAL-EASTERN SOUTH CHINA SEA

南海中部海域夏季水团的实测温盐深数据统计分析结果表明，研究区受南海暖池的影响，海域表层强度在28～31．5℃左右，呈北高南低、西高东低的特征；表层盐度在32～34．1psu左右，整体上呈南高北低、东高西低的分布特征。低盐区域主要分布在研究区西北部，与高温区域呈现重合的特点。综合研究表明，研究区受夏季风和海面净热通量的影响，海水层化作用较强，整体上混合层的厚度不大，温跃层比较发育，导致跃层的厚度比较大，最高可达170m，强度也较高，大部分区域温度梯度在0．09～0．12℃／m之间；盐跃层的上界深度和厚度整体上都低于温跃层。结合表层温度和盐度的分布特征推测研究区东部和南部表层海水存在着较厚的低温高盐水层。

The CTD data collected from 17 stations in the central and eastern part of the South China Sea on May 7, to 25, and July 1 to August 23 in 2012 indicate that under the influence of the South China Sea warm pool, the sea surface temperature at the study area was higher than 28℃. It decrea- ses from north to south, and from west to east, whereas the surface salinity was about 32psu/m or higher, and decreases from south to north and from east to west. The low salinity occurs in the north- west area, coincident with the high-temperature region. Water stratification is strong due to the im- pact of the summer monsoon and the net surface heat flux. The mixed layer is thin in thickness. The thermocline is well developed and may be up to 170m in thickness, and the gradient is higher than 0.0℃/m. The depth and thickness of the upper boundary of the halocline are lower than the thermo- cline. Combined with the distribution of surface temperature and salinity in the eastern and southern area, it suggests that there occurs a thick layer of water with low temperature and high salinity.