南海暖水的季节变化特征及数值模拟

SEASONAL CHARACTERISTICS OF THE SOUTH CHINA SEA WARM POOL AND NUMERICAL MODELING

根据Levitus资料 ,对具有立体结构的南海暖水给出了定义 ,分析发现 :南海暖水的季节变化过程可分为发展、维持、退缩和消失 4个阶段 ;就气候平均而言 ,南海暖水在季节变化中始终保持西北部浅、东南部深的特点 ;南海暖水的深度与同期温跃层上界的深度在空间分布特征与季节变化趋势上都基本类似。采用“intermediate”模式模拟了南海暖水的范围和厚度 ,结果表明发展阶段的南海暖水范围和厚度的增长主要是因为南海地区受到的局地加热。维持阶段南海暖水的厚度主要由湍流混合作用和Ekman效应来维持 ;退缩阶段南海混合层顶部的降温和冷水从底部的卷入都是南海暖水消失的主要原因。

Based on the Levitus (1982) climatological data, the South China Sea Warm Pool (SCSWP) is defined. The seasonal variation of the SCSWP can be divided into four stages. In the climatological sense, the spatial structure and seasonal variation of the SCSWP thickness is similar to that of the upper boundary of thermocline from April to October. From April to November, the SCSWP is always shallow in Northwest and deep in Southeast. An intermediate model (Wang et al, 1995) is used to simulate the extent and the thickness of the SCSWP. The model can reproduce the main characteristics of the SCSWP, which indicate that: (1) at the developing stage, the expanding of the SCSWP is controlled mainly by the local heating; (2) at the stable stage, the thickness of the SCSWP is maintained by the enhanced mixing and the Ekman transport; and (3) at the flinching stage, the SCSWP is reduced by the surface cooling and the cold water entrained into the mixed layer.