本文利用2015年3月—2021年5月热带印度洋观测网(tropical Indian Ocean observation net,TIOON)在赤道80°E、85°E和93°E布设的观测潜标所获取的环流时间序列,结合BRAN2020(Bluelink Re ANalysis)环流流速数据以及JRA-55...本文利用2015年3月—2021年5月热带印度洋观测网(tropical Indian Ocean observation net,TIOON)在赤道80°E、85°E和93°E布设的观测潜标所获取的环流时间序列,结合BRAN2020(Bluelink Re ANalysis)环流流速数据以及JRA-55(Japanese 55-year Reanalysis)气象数据,研究了印度洋赤道深层环流(1200m以下)的季节内变化特征及其驱动机制。观测结果显示,深层环流流速平均值接近0,纬向流速标准偏差范围为2.5~3.1cm·s^(-1),经向流速标准偏差范围为2.6~3.1cm·s^(-1)。纬向流和经向流的季节内周期信号强度分别占各自总流动强度的88%~91%和74%~84%,揭示了深层环流中的显著季节内周期变率特征。小波分析表明,深层纬向流季节内信号主要周期为10~100d,其中80°E处的周期较长(50~90d),而93°E处的主要为50d及更高频信号,表现为蓝移现象,即环流变化的主导频率随位置靠东而变高的现象。经向流季节内信号以60d周期最显著。赤道风应力异常是深层环流季节内变率的重要驱动因素。中海盆(80°E和85°E)深层环流季节内变率主要受纬向风应力异常驱动,通过反射波动过程调制;基于低阶斜压模态,能量通过Kelvin波在东边界反射后形成的Rossby波向深层传递。东海盆(93°E)深层环流季节内变率主要受纬向和经向风应力异常驱动,通过直接波动过程调制;基于多阶斜压模态,能量通过在环流西侧由风直接驱动产生的Yanai波向深层传递。根据线性波动理论,本研究刻画了上述赤道波的能量传播射线,结果显示地形对赤道波调制深海环流的动力过程有重要影响:中海盆的平坦地形有利于向下向西传播能量的反射波动过程,而90°E海脊可能会阻碍向下向东传播能量的直接波动过程。在平坦地形区域,正压不稳定过程在经向上无显著差异且强度弱,区域平均结果显示能量主要由平均流向环流季节内变率释放;90°E海脊附近,环流季节内变率与平均流之间存在更强的非线性动力作用,表现为环流季节内变率向平均流转移能量。本研究加深了对深层环流动力学的理解,为改进深海环流模拟提供了观测依据。展开更多
Marginal seas,as transitional zones,are closely connected to the open ocean and adjacent coastal systems.Their circulations often exhibit strong oscillatory behavior that shapes heat and salt transport,nutrient cyclin...Marginal seas,as transitional zones,are closely connected to the open ocean and adjacent coastal systems.Their circulations often exhibit strong oscillatory behavior that shapes heat and salt transport,nutrient cycling,and regional ocean-atmosphere interactions.However,the characteristics and underlying dynamics of these oscillations remain insufficiently understood.Using the unique three-layer alternating circulation in the South China Sea as an example,we show that the system undergoes a pronounced regime transition from 1993-2008 to 2009-2018.This transition is closely linked to the phase change of the Pacific Decadal Oscillation.Specifically,upper-layer cyclonic circulation intensifies during the pre-2009 but weakens during the post-2009 period,while the middle-layer anticyclonic circulation exhibits the opposite pattern.In contrast,the deep-layer circulation strengthens substantially during the post-20o9 period.These regime transitions arise from the interplay of surface wind forcing,the external exchanging current with the Pacific,and topographically modulated internal vertical coupling.The decadal trend of the upper-layer circulation is primarily wind-driven.The weakening of middle-layer circulation during pre-2oo9 is governed by pressure torque influenced by the upperlayer,whereas its post-2009 strengthening is attributed to vortex stretching associated with enhanced deep intrusion from the Pacific and a stronger deep-layer circulation.The findings clarify the oscillatory nature of South China Sea layered circulation under climate variability and highlight its role in regulating regional mass transport and ocean-atmosphere interaction.展开更多
利用高分辨率卫星海表信息和海洋历史温盐剖面数据,基于变分法重构了西北太平洋海域的三维动态温度场。与Argo(array for real-time geostrophic oceanography)温度观测剖面相比,重构温度场能够较为合理地再现海水温度的垂向变化特征,...利用高分辨率卫星海表信息和海洋历史温盐剖面数据,基于变分法重构了西北太平洋海域的三维动态温度场。与Argo(array for real-time geostrophic oceanography)温度观测剖面相比,重构温度场能够较为合理地再现海水温度的垂向变化特征,尤其是在温跃层区域,重构结果与实际观测温度廓线能够较好地吻合。文章选取了两个典型的中尺度涡旋个例,利用重构温度场分析了其从生成到衰退的整个演变过程,展示了涡旋引起的温度异常在垂直和水平分布上的动态变化。尤其是在涡旋成熟阶段,温度异常的强度和深度扩展达到最大值,表现出涡旋对海洋温跃层的显著影响。通过分析不同阶段的温度异常分布,研究揭示了冷暖核心与异常区的空间结构的演化特征。结果表明,该方法能够有效利用卫星观测海表数据重构中尺度涡旋的水下温度结构和动态演变特征,将为理解中尺度涡旋在海洋物质和热量输运提供数据支撑。展开更多
Atlantic Meridional Overturning Circulation(AMOC)plays a central role in long-term climate variations through its heat and freshwater transports,which can collapse under a rapid increase of greenhouse gas forcing in c...Atlantic Meridional Overturning Circulation(AMOC)plays a central role in long-term climate variations through its heat and freshwater transports,which can collapse under a rapid increase of greenhouse gas forcing in climate models.Previous studies have suggested that the deviation of model parameters is one of the major factors in inducing inaccurate AMOC simulations.In this work,with a low-resolution earth system model,the authors try to explore whether a reasonable adjustment of the key model parameter can help to re-establish the AMOC after its collapse.Through a new optimization strategy,the extra freshwater flux(FWF)parameter is determined to be the dominant one affecting the AMOC’s variability.The traditional ensemble optimal interpolation(EnOI)data assimilation and new machine learning methods are adopted to optimize the FWF parameter in an abrupt 4×CO_(2) forcing experiment to improve the adaptability of model parameters and accelerate the recovery of AMOC.The results show that,under an abrupt 4×CO_(2) forcing in millennial simulations,the AMOC will first collapse and then re-establish by the default FWF parameter slowly.However,during the parameter adjustment process,the saltier and colder sea water over the North Atlantic region are the dominant factors in usefully improving the adaptability of the FWF parameter and accelerating the recovery of AMOC,according to their physical relationship with FWF on the interdecadal timescale.展开更多
文摘本文利用2015年3月—2021年5月热带印度洋观测网(tropical Indian Ocean observation net,TIOON)在赤道80°E、85°E和93°E布设的观测潜标所获取的环流时间序列,结合BRAN2020(Bluelink Re ANalysis)环流流速数据以及JRA-55(Japanese 55-year Reanalysis)气象数据,研究了印度洋赤道深层环流(1200m以下)的季节内变化特征及其驱动机制。观测结果显示,深层环流流速平均值接近0,纬向流速标准偏差范围为2.5~3.1cm·s^(-1),经向流速标准偏差范围为2.6~3.1cm·s^(-1)。纬向流和经向流的季节内周期信号强度分别占各自总流动强度的88%~91%和74%~84%,揭示了深层环流中的显著季节内周期变率特征。小波分析表明,深层纬向流季节内信号主要周期为10~100d,其中80°E处的周期较长(50~90d),而93°E处的主要为50d及更高频信号,表现为蓝移现象,即环流变化的主导频率随位置靠东而变高的现象。经向流季节内信号以60d周期最显著。赤道风应力异常是深层环流季节内变率的重要驱动因素。中海盆(80°E和85°E)深层环流季节内变率主要受纬向风应力异常驱动,通过反射波动过程调制;基于低阶斜压模态,能量通过Kelvin波在东边界反射后形成的Rossby波向深层传递。东海盆(93°E)深层环流季节内变率主要受纬向和经向风应力异常驱动,通过直接波动过程调制;基于多阶斜压模态,能量通过在环流西侧由风直接驱动产生的Yanai波向深层传递。根据线性波动理论,本研究刻画了上述赤道波的能量传播射线,结果显示地形对赤道波调制深海环流的动力过程有重要影响:中海盆的平坦地形有利于向下向西传播能量的反射波动过程,而90°E海脊可能会阻碍向下向东传播能量的直接波动过程。在平坦地形区域,正压不稳定过程在经向上无显著差异且强度弱,区域平均结果显示能量主要由平均流向环流季节内变率释放;90°E海脊附近,环流季节内变率与平均流之间存在更强的非线性动力作用,表现为环流季节内变率向平均流转移能量。本研究加深了对深层环流动力学的理解,为改进深海环流模拟提供了观测依据。
基金supported by the National Natural Science Foundation of China(42376024and 42450181)the Science and Technology Development Fund,Macao SAR(File/Project no.001/2024/SKL)+2 种基金supported by the Centre for Regional Oceans in the University of Macao(SP2025-00005-CRO)CORE,which is a joint research center for ocean research between Laoshan Laboratory and HKUSTsubstantially supported by a grant from the Research Grants Council of the Hong Kong Special Administrative Region,China(AoE/P-601/23-N and GRF 16310724).
文摘Marginal seas,as transitional zones,are closely connected to the open ocean and adjacent coastal systems.Their circulations often exhibit strong oscillatory behavior that shapes heat and salt transport,nutrient cycling,and regional ocean-atmosphere interactions.However,the characteristics and underlying dynamics of these oscillations remain insufficiently understood.Using the unique three-layer alternating circulation in the South China Sea as an example,we show that the system undergoes a pronounced regime transition from 1993-2008 to 2009-2018.This transition is closely linked to the phase change of the Pacific Decadal Oscillation.Specifically,upper-layer cyclonic circulation intensifies during the pre-2009 but weakens during the post-2009 period,while the middle-layer anticyclonic circulation exhibits the opposite pattern.In contrast,the deep-layer circulation strengthens substantially during the post-20o9 period.These regime transitions arise from the interplay of surface wind forcing,the external exchanging current with the Pacific,and topographically modulated internal vertical coupling.The decadal trend of the upper-layer circulation is primarily wind-driven.The weakening of middle-layer circulation during pre-2oo9 is governed by pressure torque influenced by the upperlayer,whereas its post-2009 strengthening is attributed to vortex stretching associated with enhanced deep intrusion from the Pacific and a stronger deep-layer circulation.The findings clarify the oscillatory nature of South China Sea layered circulation under climate variability and highlight its role in regulating regional mass transport and ocean-atmosphere interaction.
文摘利用高分辨率卫星海表信息和海洋历史温盐剖面数据,基于变分法重构了西北太平洋海域的三维动态温度场。与Argo(array for real-time geostrophic oceanography)温度观测剖面相比,重构温度场能够较为合理地再现海水温度的垂向变化特征,尤其是在温跃层区域,重构结果与实际观测温度廓线能够较好地吻合。文章选取了两个典型的中尺度涡旋个例,利用重构温度场分析了其从生成到衰退的整个演变过程,展示了涡旋引起的温度异常在垂直和水平分布上的动态变化。尤其是在涡旋成熟阶段,温度异常的强度和深度扩展达到最大值,表现出涡旋对海洋温跃层的显著影响。通过分析不同阶段的温度异常分布,研究揭示了冷暖核心与异常区的空间结构的演化特征。结果表明,该方法能够有效利用卫星观测海表数据重构中尺度涡旋的水下温度结构和动态演变特征,将为理解中尺度涡旋在海洋物质和热量输运提供数据支撑。
基金supported by the National Key R&D Program of China [grant number 2023YFF0805202]the National Natural Science Foun-dation of China [grant number 42175045]the Strategic Priority Research Program of the Chinese Academy of Sciences [grant number XDB42000000]。
文摘Atlantic Meridional Overturning Circulation(AMOC)plays a central role in long-term climate variations through its heat and freshwater transports,which can collapse under a rapid increase of greenhouse gas forcing in climate models.Previous studies have suggested that the deviation of model parameters is one of the major factors in inducing inaccurate AMOC simulations.In this work,with a low-resolution earth system model,the authors try to explore whether a reasonable adjustment of the key model parameter can help to re-establish the AMOC after its collapse.Through a new optimization strategy,the extra freshwater flux(FWF)parameter is determined to be the dominant one affecting the AMOC’s variability.The traditional ensemble optimal interpolation(EnOI)data assimilation and new machine learning methods are adopted to optimize the FWF parameter in an abrupt 4×CO_(2) forcing experiment to improve the adaptability of model parameters and accelerate the recovery of AMOC.The results show that,under an abrupt 4×CO_(2) forcing in millennial simulations,the AMOC will first collapse and then re-establish by the default FWF parameter slowly.However,during the parameter adjustment process,the saltier and colder sea water over the North Atlantic region are the dominant factors in usefully improving the adaptability of the FWF parameter and accelerating the recovery of AMOC,according to their physical relationship with FWF on the interdecadal timescale.
