印度尼西亚海及周边海域层结的时空变化特征分析

本文利用World Ocean Atlas 2013 (WOA13)和Simple Ocean Data Assimilation version 3.1.1 (SODA v3.3.1)温盐资料，分析印尼贯穿流(ITF)路径及所经印度尼西亚海及周边西太平洋、南海和东印度洋海域的层结强度(N2)和跃层特征的三维时空变化特征。结果表明，气候态下ITF 3条路径上跃层平均N2差异较小，其中中部路径平均值最大，为10?3.68 s?2，东部路径平均值最小，为10?3.71 s?2；各路径跃层深度和厚度存在明显差异，东部路径跃层深度和厚度最大，分别为124 m和192 m，中部次之，西部最小为99 m和143 m，并且印尼海的跃层深度和厚度平均值均小于其他海域。印尼海N2存在显著的季节变化和4～7 a的多年周期变化，其中年际变化可能主要受厄尔尼诺?南方涛动事件影响。季节上，在印尼海域内，ITF 3条路径夏季层结强度均小于冬季(北半球夏冬季)，夏、冬两季N2差值最大可达到两个量级。1993?2015年的长期变化趋势显示，印尼海及周边大部分海域的层结强度呈现增强趋势，其中印度洋中部和哈马黑拉海23 a内最大层结增强近0.1个量级。

Analysis of the spatiotemporal characteristics of stratification in the Indonesian seas and surrounding waters

Using climatological and monthly temperature and salinity data from the World Ocean Atlas 2013 (WOA13) and the Simple Ocean Data Assimilation Version 3.3.1 (SODA v3.3.1), this study analyzes the 3D spatiotemporal characteristics of stratification (N2) and pycnocline along the pathways of Indonesia Throughflow (ITF) in the Indonesian seas and surrounding waters in the western Pacific, the South China Sea and the eastern Indian Ocean. The results show that the climatologically mean N2 in pycnocline has little difference in all the pathways of the ITF, and the largest value is 10?3.68 s?2 in the central pathway and the smallest is 10?3.71 s?2 in the eastern pathway. The differences are significant for the depth (D_pyc) and thickness (H_pyc) of the pycnocline along three pathways. The largest values of D_pyc and H_pyc are 124 m and 192 m in the eastern pathway, respectively, followed by values of 99 m and 143 m in the central pathway. Compared to the surrounding oceans, the mean pycnocline depth and thickness of the three pathways in the Indonesian seas are smaller than those in other seas. N2 and D_pyc have remarkably seasonal variation with period of one year and inter-annual variability with periods of 4?7 year cycles. The interannual variability may be mainly affected by the ENSO event. Seasonally, the summer N2 in the Indonesia seas is less than that in winter (northern hemisphere winter and summer), and the maximum difference between winter and summer can reach two orders of magnitude. The long-term variation trend of N2 from 1993 to 2015 shows that the stratification intensifies in most areas of Indonesian seas and surrounding waters, where N2 strengthened by nearly 0.1 order of magnitude in 23 years in the middle of the India Ocean and Halmahera Sea.