Volume 40 Issue 1
Feb.  2021
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Wei Duan, Xuhua Cheng, Xiuhua Zhu, Tian Ma. Variability in upper-ocean salinity stratification in the tropical Pacific Ocean[J]. Acta Oceanologica Sinica, 2021, 40(1): 113-125. doi: 10.1007/s13131-020-1597-x
 Citation: Wei Duan, Xuhua Cheng, Xiuhua Zhu, Tian Ma. Variability in upper-ocean salinity stratification in the tropical Pacific Ocean[J]. Acta Oceanologica Sinica, 2021, 40(1): 113-125.

# Variability in upper-ocean salinity stratification in the tropical Pacific Ocean

##### doi: 10.1007/s13131-020-1597-x
Funds:  The National Key R&D Program of China under contract No. 2018YFA0605702; the National Natural Science Foundation of China under contract Nos 41876002 and 41776002; the Fundamental Research Funds for the Central Universities under contract Nos 2017B04714 and 2017B4114.
• Corresponding author: E-mail: xuhuacheng@hhu.edu.cn
• Accepted Date: 2020-04-05
• Available Online: 2021-04-21
• Publish Date: 2021-01-25
• Using a gridded array for real-time geostrophic oceanography (Argo) program float dataset, the features of upper-ocean salinity stratification in the tropical Pacific Ocean are studied. The salinity component of the squared Brunt-Väisälä frequency ${N}^{2}$ (${N}_{S}^{2}$) is used to represent salinity stratification. Layer-max ${N}_{S}^{2}$ (LMN), defined as the ${N}_{S}^{2}$ maximum over the upper 300 m depth, and halocline depth (HD), defined as the depth where the ${N}_{S}^{2}$ maximum is located, are used to specifically describe the intensity of salinity stratification. Salinity stratification in the Topical Pacific Ocean has both spatial and temporal variability. Over the western and eastern equatorial Pacific, the LMN has a large magnitude with a shallow HD, and both have completely opposite distributions outside of the equatorial region. An obvious seasonal cycle in the LMN occurs in the north side of eastern equatorial Pacific and freshwater flux forcing dominates the seasonal variations, followed by subsurface forcing. At the eastern edge of the western Pacific warm pool around the dateline, significant interannual variation of salinity stratification occurs and is closely related to the El Niño Southern Oscillation event. When an El Niño event occurs, the precipitation anomaly freshens sea surface and the thermocline shoaling induced by the westerly wind anomaly lifts salty water upward, together contribute to the positive salinity stratification anomaly over the eastern edge of the warm pool. The interannual variations in ocean stratification can slightly affect the propagation of first baroclinic gravity waves.

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###### 通讯作者: 陈斌, bchen63@163.com
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沈阳化工大学材料科学与工程学院 沈阳 110142

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