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| 南太平洋和南印度洋亚南极模态水潜沉率的长期变化趋势 |
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刘凯1,2,3, 高山1,2,3,4, 侯颖琳1,2,3, 赵军1,2,3, 王凡1,2,3,4
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1.中国科学院海洋研究所 山东青岛 266071;2.中国科学院海洋环流与波动重点实验室 山东青岛 266071;3.中国科学院大学 北京 100049;4.青岛海洋科学与技术试点国家实验室 海洋动力过程与气候功能实验室 山东青岛 266237
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| 摘要: |
| 亚南极模态水(sub-Antarctic mode water,SAMW)的潜沉过程与全球变暖减缓现象密切相关。为了增进对亚南极模态水长期变化特征的认识,使用一个高分辨率长时间序列的海洋模式数据对SAMW的潜沉率变化趋势的空间分布进行了系统地分析。结果显示,在1958~2016年间,SAMW的潜沉量在南太平洋和南印度洋在长时间段上存在着相反的趋势变化,即在南太平洋增大,在南印度洋减少,这与已有研究结果相符。但进一步的分析发现,SAMW潜沉量的空间分布存在着明显的差异。在南印度洋,其北部潜沉区的潜沉率仅有很微弱的上升趋势,而位于南部潜沉区的潜沉率则有明显的下降趋势。与此同时,在南太平洋中,其西部潜沉区的潜沉率趋势非常小,而东部潜沉区的水的潜沉有明显上升的长期趋势。总体而言,密度较大的SAMW潜沉水团比密度较小的潜沉水团表现出更显著的长期变化的趋势。南部变化趋势明显的潜沉水量大概占总潜沉水量的60%,由此可知SAMW的总体趋势更多地来自其南部密度更大的潜沉区的贡献。进一步的分析表明,SAMW潜沉区的混合层的长期变化趋势与潜沉率的长期变化趋势之间存在较为一致的空间分布。其中,在南太平洋,东侧潜沉区的混合层的长期增大趋势,主要由于风应力增大的作用,而西侧潜沉区的混合层的长期减小趋势,则主要因为海表浮力强迫的控制;在南印度洋,南侧潜沉区的潜沉率长期减小趋势更多的是受到浮力强迫的影响,而西北部的潜沉率长期增加趋势则主要由风应力增强导致的。 |
| 关键词: 潜沉率 长期变化趋势 混合层 水团 |
| DOI：10.11693/hyhz20220300054 |
| 分类号:P731.27 |
| 基金项目:国家重点研发计划,2016YFC0301203号;国家自然科学基金项目,41676009号。 |
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| LONG-TERM TRENDS IN SUBANTARCTIC MODE WATER SUBDUCTION RATES IN THE SOUTH PACIFIC AND SOUTH INDIAN OCEAN |
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LIU Kai1,2,3, GAO Shan1,2,3,4, HOU Ying-Lin1,2,3, ZHAO Jun1,2,3, WANG Fan1,2,3,4
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1.Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China;2.Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao 266071, China;3.University of Chinese Academy of Sciences, Beijing 100049, China;4.Laboratory for Ocean Dynamics and Climate, Pilot National Laboratory for Marine Science and Technology(Qingdao), Qingdao 266237, China
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| Abstract: |
| The subduction process of subantarctic modal water (SAMW) is closely related to the global warming hiatus. We systematically analyzed and calculated the spatial distribution of SAMW subduction rate trends using the high-resolution and long time series of ocean model data. Results show that the subduction rate of SAMW tends to increase in the South Pacific but to decrease in the Southern Indian Ocean between 1958~2016, which is consistent with the results of previous studies. However, further analysis revealed a clear spatial variation of the trend in the subduction of SAMW. In the Southern Indian Ocean, the subduction rate in the northern subduction zone (sea surface density (SSD) at 26.5~26.8 kg/m3) shows a very weak increasing trend, while in the southern subduction zone (water with SSD at 26.8~27.1 kg/m3) it presents an obvious long-term decreasing trend. Meanwhile, the South Pacific Ocean shows a weak trend of water subduction rate in the western subduction zone (SSD at 26.5~26.9 kg/m3), but an obvious increasing long-term trend of water subduction in the eastern subduction zone (SSD at 26.9~27.1 kg/m3). In general, the SAMW with higher density on the sea surface show more significant long-term trends than the less surface dense subducted water masses, accounting for about 60% of the total SAMW. In other words, the SAMW contributes more in overall from the southern part where surface density is higher. Additional studies uncovered a considerably consistent spatial distribution between the long-term variation trends of the mixed layer in the SAMW subduction zone and the long-term trends of the subduction rate. Among them, in the main subduction zone of the South Pacific, the long-term increasing trend of the mixing layer in the east subduction zone is mainly due to the increase of wind stress curl, while the long-term decreasing trend of the mixed layer in the western subduction zone is mainly due to the control of sea surface buoyancy forcing. In the main subduction zone of the southern Indian Ocean, the long-term decreasing trend of the subduction rate in the southern subduction zone is more influenced by buoyancy forcing, while the long-term increasing trend of the subduction rate in the northwestern region is mainly due to the contribution of increased wind stress curl. |
| Key words: subduction rate long-term trends mixed layer water mass |
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