热带太平洋盐度变化:2015-2017年盐度异常  

The robust salinity anomaly event during 2015-2017 in the tropical Pacific Ocean

作　　者：史荒原 杜凌 徐道欢 Shi Huangyuan;Du Ling;Xu Daohuan(College of Oceanic and Atmospheric Sciences,Ocean University of China,Qingdao 266100,China)

机构地区：[1]中国海洋大学海洋与大气学院,山东青岛266100

出　　处：《海洋学报》2020年第3期47-58,共12页

基　　金：国家自然科学基金(41376008,41576020);全球变化与海气相互作用专项(GASI-03-01-01-09);国家重点基础研究发展计划项目(2012CB417401)。

摘　　要：本文利用Argo海水盐度资料、海流同化数据和同期大气再分析数据,探讨热带太平洋盐度趋势变化和相关动力过程。Argo资料显示,2015-2017年热带太平洋出现显著的盐度异常(SAE),这是改变长期趋势的主要原因,表现为表层显著淡化和次表层咸化特征。这种盐度异常具有明显的区域性特征和垂直结构的差异,体现在热带太平洋北部海区(NTP)和南太平洋辐合区(SPCZ)表层淡化,盐度最大变幅为0.71~0.92,淡化可以达到混合层底;热带太平洋南部海区(STP)次表层咸化,最大变幅为0.46,主要发生在温跃层附近,期间盐度异常沿着等位密面从西向东扩展。平流和挟卷是与SAE密切相关的海洋动力过程,两者在NTP淡化海域有着持续而较为显著的影响,在SPCZ淡化、STP咸化海域后期贡献也较大,其中盐度平流对热带太平洋海区盐度变化起主要贡献。NTP淡化海区表层淡水通量和STP咸化海区密度补偿引起的混合也是SAE的重要影响因素。Salinity linear trends and their contributed dynamics processes in the tropical Pacific Ocean were investigated with the Argo salinity and temperature fields, current assimilations and atmospheric reanalysis datasets. The robust salinity anomaly event(SAE) occurred in the tropical Pacific Ocean during 2015-2017, which resulted possibly in the reversing of Argo salinity long-term trends. Such SAE was characterized as distinct regional discrepancies and vertical structures. Significant surface freshening occurred in the northern tropical Pacific(NTP) and Southern Ocean Convergence Zone(SPCZ), whose remarkable freshening maximum could reach 0.71-0.92 and covered the upper mixed layer. Another subsurface salinification in the southern tropical Pacific(STP) with the maximum of 0.46 was found around thermocline layer. Moreover, the salinity anomalies in SAE can expand from west to east along the isopycnal layers. Salinity advection and entrainment were exhibited as the fundamental dynamic processes to the SAE event in the tropical Pacific Ocean, while advection term acted as the major contribution to salinity variability. Both of the dynamic factors played important role on SAE features during the whole event in the NTP and later period in the SPCZ and STP. The surface freshwater flux and subsurface mixing induce by density compensation were also supplements to the SAE events in the NTP freshening and STP salinification respectively.

关 键 词：盐度异常 平流和挟卷 密度层结 热带太平洋 

分 类 号：P731.12[天文地球—海洋科学]