| 摘要: |
| 亚南极模态水（SAMW）的潜沉过程与全球变暖减缓现象密切相关。通过对一个高分辨率长时间序列的海洋模式数据进行分析后显示，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的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的总体趋势更多的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: |
| 基金项目:国家重点研发计划; 国家自然科学基金项目 |
附件 |
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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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liukai, gaoshan, houyinglin, zhaojun, wangfan
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Institute of Oceanology, Chinese Academy of Sciences
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| Abstract: |
| The subduction process of subantarctic modal water (SAMW) is closely related to the global warming hiatus phenomenon. An analysis of ocean model data of a high-resolution and long time series shows that the subduction rate of SAMW indeed has an opposite trend in the South Pacific and the Southern Indian Ocean over a longer period, i.e., it increases in the South Pacific and decreases in the Southern Indian Ocean, which is consistent with the results of previous studies. However, further analysis shows that there is a clear spatial variation of the trends in the subduction of SAMW. In the Southern Indian Ocean, the subduction rate in the northern subduction zone (water with sea surface density (SSD) at 26.5〖~26.8kg/m〗^3) has a very weak increasing trend, while the subduction rate in the southern subduction zone (water with SSD at 26.8〖~27.1kg/m〗^3) has a significant decreasing long-term trend. Meanwhile, in the South Pacific Ocean, there is a weak trend of water subduction rate in the western subduction zone (SSD at 26.5〖~26.9kg/m〗^3), while there is a significant increasing long-term trend of water subduction in the eastern subduction zone (SSD at 26.9〖~27.1kg/m〗^3). In conclusion, the SAMW with higher density on the sea surface show more significant long-term trends than the less surface dense subducted water masses, and the trend is calculated to account for about 60% of the total SAMW. This shows that the overall contribution of SAMW is more from the southern part with higher surface density. Further studies show that there is a more consistent spatial distribution between the long-term 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 region where the long-term trend of the mixed layer in the subduction zone located on the eastern side of the basin is increasing is mainly due to the effect of the increasing contribution of wind stress curl, while the region where the long-term decreasing trend of the mixed layer in the subduction zone located on the western side of the basin is mainly due to the control of the buoyancy forcing of the sea surface;. 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 |