南海北部冬季混合层深度的年际变化特征  

Interannual Variation in Winter Mixed Layer Depth in the North of the South China Sea

作　　者：王一格 王玉 Wang Yige;Wang Yu(College of Oceanic and Atmospheric Sciences,Ocean University of China,Qingdao 266100,China;National Marine Environmental Monitoring Center,Dalian 116023,China)

机构地区：[1]中国海洋大学海洋与大气学院,山东青岛266100 [2]国家海洋环境监测中心,辽宁大连116023

出　　处：《中国海洋大学学报（自然科学版）》2024年第11期25-33,共9页Periodical of Ocean University of China

基　　金：国家自然科学基金项目(42076003)资助。

摘　　要：基于简单海洋资料同化(Simple ocean data assimilation,SODA)再分析数据集v2.2.4中的温盐数据,本文使用小波能量谱分析了冬季南海北部混合层深度(Mixed layer depth,MLD)的年际变化,发现其存在2~4 a与7~8 a的准周期年际振荡。不同年际信号的主导因素具有显著差异,其中短周期(2~4 a)年际变化的主要影响因子为海表净热通量和风应力旋度,但海表净热通量等局地因素与长周期(7~8 a)年际变化之间并无明显相关。吕宋海峡水交换的纬向流速垂向变化显著,能够调整南海北部的垂向密度分布,因此MLD与吕宋海峡水通量差(Luzon Strait transport,LST,ΔLST)之间存在密切联系。ΔLST的正(负)异常表示通过海峡断面0~70 m(70~140 m)进入的高盐水相对增加,强化了其对南海北部混合层内(混合层之下)水体的增密作用,使层结强度降低(增强),进而导致MLD加深(变浅)。Based on SODA v2.2.4 reanalysis data,this paper investigates the interannual variation of winter mixed layer depth(MLD)in the northern South China Sea through wavelet power spectrum,which exhibits significant interannual variations of two predominant periods(2~4 a and 7~8 a).It is indicated that sea surface net heat flux and wind stress curl are generally responsible for control on short-period variation(2~4 a),nevertheless,there was unobvious correlation between local factors and long-period variation(7~8 a).The zonal velocity of Luzon Strait transport(LST)with large vertical gradient,can affect the vertical mixing by adjusting the upper seawater density,thus influencing the MLD in the northern South China Sea on a time scale of 7~8 a.The positive(negative)anomalies of the transport difference between 0~70 m and 70~140 m(ΔLST),representing a relative increase in high saline intrusion entering at depths between surface and 70 m(70 and 140 m),comparatively densify the water inside(below)mixed layer,resulting in stronger(weaker)stratification and deeper(shallower)MLD.

关 键 词：南海 混合层 年际变化 吕宋海峡水交换 

分 类 号：P722.7[天文地球—海洋科学]