热带东太平洋淡水池的季节变化 *

文章利用观测和模式数据, 并基于混合层盐度收支方法, 研究了热带东太平洋淡水池的季节变化。研究发现: 热带东太平洋淡水池具有显著的季节变化, 由海表强迫(蒸发与降水)、水平平流和次表层过程共同控制。淡水池的季节变化主要分为扩张与收缩两个阶段。4月至11月为扩张阶段, 淡水池向西扩张, 最大体积和面积比最小时扩大将近一倍, 分别达到2.83×10 ⁵km ³和8.94×10 ⁶km ²。热带辐合带向北移动带来的强降水是淡水池扩张的主要原因, 海表强迫决定了混合层盐度降低。12月至3月为淡水池收缩阶段, 海表淡水通量的减弱、水平平流和次表层过程的增强导致混合层盐度升高, 淡水池向东收缩。

Seasonal variability of the Eastern Tropical Pacific Fresh Pool *

Using the observations and a mixed layer salinity budget from an ocean general circulation model, we investigate the seasonal variability of the eastern tropical Pacific freshwater pool (EPFP). The EPFP has significant seasonal variation, which is controlled by the surface forcing (evaporation and precipitation), horizontal advection and subsurface processes. The seasonal changes in EPFP are mainly divided into two phases: expansion and contraction phases. From April to November, the freshwater pool expands to the west and the freshwater volume and area doubles to 2.83×10 ⁵ km ³ and 8.94×10 ⁶ km ², respectively. The strong precipitation brought by the northward movement of the intertropical convergence zone is the main reason for the expansion of the EPFP: the surface forcing determines the reduction of the mixed layer salinity. From December to March, when the EPFP shrinks, the increasing of the mixed layer salinity is attributed to the weakening of surface freshwater flux and the enhancement of horizontal advection and subsurface processes.