热带太平洋温跃层深度的年代际变化特征及原因

Characteristics and Mechanism of the Decadal Variability of Thermocline in Tropical Pacific Ocean

利用SODA数据分析了20世纪70年代气候跃迁前后热带太平洋温跃层变化的季节特征,研究了NCEP/NCAR再分析资料中的风场变化与温跃层变化之间的关系。研究结果表明:1)在1976—1977年气候跃迁之后,温跃层深度存在显著的年代际变化。在热带太平洋东部的秘鲁沿岸海域温跃层变深,而在10°S^10°N的热带太平洋其他海域温跃层均呈现变浅趋势;2)温跃层深度的年代际变化存在显著的季节差异。总体表现为,温跃层变浅的最显著区域随着季节的推移由东太平洋逐渐移至西太平洋并且变浅的幅度增大;3)热带太平洋海表面风场的年代际变化导致的赤道西风异常及风场异常的散度场是温跃层变化的主要原因。

Characteristics and mechanism of the decadal variability of thermocline in tropical Pacific Ocean are investigated using the SODA and NCEP/NCAR reanalysis data.The results show that the change in thermocline depth in tropical Pacific after the ＂ 1976-1977 climate shift＂ is obvious.The thermocline in eastern tropical Pacific,close to Peru coast,becomes deeper after the climate shift but shallower in equatorial Pacific between 10°S-10°N.The change in thermocline shows remarkable seasonal characteristics：the location of the maximum change in thermocline depth moves from eastern tropical Pacific to the west and its magnitude increases with season.Analysis further shows that the change in sea surface winds in tropical Pacific and associated wind divergence play a key role in the change in thermocline.