| 摘要: |
| 为研究赤道太平洋海表二氧化碳分压(pCO2sw)年际变化的机制, 基于中科院海洋所宋金明研究团队于2021年发布的中国首套全球海表二氧化碳分压数据产品, 使用相关性分析、经验正交函数(empirical orthogonal function, EOF)分析和奇异值分解(singular value decomposition, SVD)等方法, 研究了2005~2019年赤道太平洋pCO2sw气候态分布及其去趋势后的年际异常的时空演变特征; 结合pCO2sw与多种参数的相关性和厄尔尼诺-南方涛动(El Niño-Southern Oscillation, ENSO)过程探讨了赤道中西太平洋pCO2sw年际异常中心形成的原因。研究结果显示, 热带太平洋pCO2sw季节变化、年际异常及其EOF第一模态特征向量沿赤道均出现两个中心, 其中一个在赤道中西太平洋日界线附近, 另一个在赤道中东太平洋120°W附近; 且不同季节、不同ENSO相位时期前者的位置会沿赤道有东西向移动。赤道太平洋pCO2sw年际异常的EOF第一模态时间系数与Niño 3.4海表温度指数呈极强的负相关性(二者间的相关系数为-0.853); 赤道中西太平洋pCO2sw年际异常与海表温度、纬向风速、虚拟盐通量和降水等异常均呈负相关, 而与叶绿素浓度、盐度、位势密度和混合层深度等异常呈正相关, 同时也与经向流速异常有关。据此, 提出一种关于ENSO调制赤道中西太平洋pCO2sw年际变率的物理机制:当El Niño发生时, 热带太平洋信风减弱, 赤道西太平洋出现西风异常, 主要降水带和沃克环流的上升支沿赤道东移, 使得赤道中西太平洋降水增多(虚拟盐通量、进入海洋表层的淡水通量增加等), 导致盐度降低、上层海洋层结增强和垂向混合减弱, 使得次表层富含二氧化碳的冷水上涌减少, 导致pCO2sw变小。 |
| 关键词: 海表二氧化碳分压 厄尔尼诺-南方涛动(ENSO) 赤道中西太平洋 淡水通量 海洋动力过程 |
| DOI：10.11693/hyhz20221100294 |
| 分类号: |
| 基金项目:国家自然科学基金项目,42030410号；崂山实验室科技创新项目,LSKJ202202402号；中国科学院战略性先导科技专项,XDB40000000号,XDB42000000号；南京信息工程大学人才启动经费项目 |
|
| SPATIO-TEMPORAL VARIABILITY OF SEA SURFACE PARTIAL PRESSURE OF CARBON DIOXIDE AND ITS RELATIONSHIP WITH PHYSICAL FIELDS IN THE TROPICAL PACIFIC OCEAN |
|
JIANG Zheng1,2,3, ZHANG Rong-Hua4,5,6,3, GONG Xun2
|
|
1.CAS Key Laboratory of Ocean Circulation and Waves, Institute of Oceanology, Qingdao 266071, China;2.Hubei Key Laboratory of Marine Geological Resources, China University of Geosciences, Wuhan 430074, China;3.University of Chinese Academy of Sciences, Beijing 100049, China;4.School of Marine Sciences, Nanjing University of Information Science &5.Technology, Nanjing 210044, China;6.Laoshan Laboratory, Qingdao 266237, China
|
| Abstract: |
| To investigate the mechanism of interannual variability of sea surface partial pressure of carbon dioxide (pCO2sw) in the Equatorial Pacific Ocean, we used correlation analysis, empirical orthogonal function analysis (EOF), and singular value decomposition (SVD) methods to investigate the multi-temporal and multi-spatial characteristics of climatological distribution and interannual anomalies of pCO2sw over the western-central equatorial Pacific Ocean from 2005 to 2019, based on China's first dataset of global pCO2sw data products (2021) produced by Song Jin-Ming's team, Institute of Oceanology, Chinese Academy of Sciences. Correlations between pCO2swand various variables are related with El Niño-Southern Oscillation (ENSO), providing a way to explain the causes of pCO2sw anomaly center over the western-central equatorial Pacific Ocean. The results show that there are two pCO2swanomaly centers over the western-central equatorial Pacific Ocean on seasonal and interannual scales:one near the dateline of the western-central equatorial Pacific Ocean, and another near 120°W in the eastern equatorial Pacific. Meanwhile, two pCO2sw anomaly centers' locations changed along the equator in different seasons and different ENSO phases. We performed an EOF analysis for the pCO2sw anomalies in the tropical Pacific Ocean to improve the understanding of these phenomena, which are also obvious in the leading mode (EOF1). In terms of the relationship between pCO2sw and other variables, the correlation coefficient between the EOF1's first PC (PC1) of pCO2sw anomalies and the Niño 3.4 index is -0.853, which indicates that interannual anomalies of pCO2sw has a significant negative correlation with ENSO. The SVD analyses show that pCO2sw has a negative correlation with anomalies of sea surface temperature, zonal wind speed, virtual salt flux, and precipitation, whereas it has a positive correlation with anomalies of chlorophyll concentration, salinity, geopotential density, and mixed layer depth. Based on these analyses, we proposed a physical mechanism for modulation of pCO2swby ENSO in the western-central equatorial Pacific Ocean:when El Niño occurs, the westerly wind anomalies appear in the western equatorial Pacific. As the trade wind weakens, a main precipitation zone and the ascending branch of the Walker circulation simultaneously move eastward along the equator, which increases the precipitation over the western-central equatorial Pacific Ocean (an increase in virtual salt flux, freshwater flux, etc.), and leads to an increase in the ocean stratification and a weakened vertical mixing. Finally, All of those processes result in the suppression of the upwelling (CO2-rich subsurface water) from the subsurface layer, thus causing a decrease in pCO2sw. |
| Key words: sea surface partial pressure of carbon dioxide El Niño-Southern Oscillation (ENSO) the western-central equatorial Pacific Ocean freshwater flux oceanic dynamical process |
