In general,a mesoscale cyclonic(anticyclonic)eddy has a colder(warmer)core,and it is considered as a cold(warm)eddy.However,recently research found that there are a number of"abnormal"mesoscale cyclonic(anti...In general,a mesoscale cyclonic(anticyclonic)eddy has a colder(warmer)core,and it is considered as a cold(warm)eddy.However,recently research found that there are a number of"abnormal"mesoscale cyclonic(anticyclonic)eddies associated with warm(cold)cores in the South China Sea(SCS).These"abnormal"eddies pose a challenge to previous works on eddy detection,characteristic analysis,eddy-induced heat and salt transports,and even on mesoscale eddy dynamics.Based on a 9-year(2000–2008)numerical modelling data,the cyclonic warm-core eddies(CWEs)and anticyclonic cold-core eddies(ACEs)in the SCS are analyzed.This study found that the highest incidence area of the"abnormal"eddies is the northwest of Luzon Strait.In terms of the eddy snapshot counting method,8620 CWEs and 9879 ACEs are detected,accounting for 14.6%and 15.8%of the total eddy number,respectively.The size of the"abnormal"eddies is usually smaller than that of the"normal"eddies,with the radius only around 50 km.In the generation time aspect,they usually appear within the 0.1–0.3 interval in the normalized eddy lifespan.The survival time of CWEs(ACEs)occupies 16.3%(17.1%)of the total eddy lifespan.Based on two case studies,the intrusion of Kuroshio warm water is considered as a key mechanism for the generation of these"abnormal"eddies near the northeastern SCS.展开更多
北极海冰变化与冬季欧亚大陆气温异常变化存在密切联系,而冬季冷高压系统的频繁活动对于西伯利亚以及东亚地区降温产生直接影响,在“北极放大”以及未来北极海冰退缩情景下,西伯利亚近地面反气旋活动如何变化值得深入探究。本研究利用...北极海冰变化与冬季欧亚大陆气温异常变化存在密切联系,而冬季冷高压系统的频繁活动对于西伯利亚以及东亚地区降温产生直接影响,在“北极放大”以及未来北极海冰退缩情景下,西伯利亚近地面反气旋活动如何变化值得深入探究。本研究利用基于深度学习的Mask R-CNN反气旋客观识别算法对欧亚大陆冬季天气尺度反气旋进行识别,使用欧洲中期天气预报中心(European Centre for Medium-Range Weather Forecasts,ECMWF)ERA5再分析资料、美国国家海洋和大气管理局(National Oceanic and Atmospheric Administration,NOAA)OISST V2.1每日海冰密集度数据集以及MIROC6模式输出资料,进一步研究了在未来北极海冰迅速退缩的背景下,前期秋季海冰异常变化可能对反气旋和冷空气活动产生的影响及其机制。结果表明,1981-2022年秋季巴伦支海-卡拉海区域(Barents-Kara Sea,BKS)海冰指数减下降,而欧亚大陆中高纬度特别是西伯利亚区域的气温显著下降,冷空气质量异常堆积,反气旋活动携带的冷空气质量增多。进一步利用北极放大计划(Polar Amplification Model Intercomparison Project,PAMIP)中的模式资料,统计欧亚大陆反气旋在未来北极海冰较少情景下的活动变化规律,发现海冰减少条件下,西伯利亚区是欧亚大陆反气旋的主要影响和生消地之一,该区域反气旋具有局地活动特征,对准定常的西伯利亚冷高压以及冷池区冷空气积聚起重要促进作用。气温在欧亚大陆北边缘增高但在欧亚大陆中纬度呈显著下降特征,伴随着欧亚大陆大部分地区极寒天数增多。进一步研究发现秋季BKS海冰状况可作为前兆因子对后期冬季反气旋活动以及气温异常产生影响,该地区海冰状况引起区域位涡经向梯度显著降低,从而使上游东欧平原阻塞发生频率增大,有利于反气旋活动增强和冷空气的输送,促使东亚冬季寒冷趋势加剧。展开更多
基金The National Natural Science Foundation of China under contract Nos 41906008,41806039,41806030,42076021,41676010 and 41706205the State Key Laboratory of Tropical Oceanography,South China Sea Institute of Oceanology,Chinese Academy of Sciences under contract Nos LTO1902 and LTO1807+9 种基金the Strategic Priority Research Program of Chinese Academy of Sciences under contract No.XDB42000000the Youth Innovation Promotion Association CAS under contract No.2017397the Pearl River S&T Nova Program of Guangzhou under contract No.201806010105the Open Fund of State Key Laboratory of Satellite Ocean Environment Dynamics,Second Institute of OceanographyMNR under contract No.QNHX2022the Startup Foundation for Introducing Talent of Nanjing University of Information Science&Technology under contract No.2019r049the Startup Foundation for Introducing Talent of Zhejiang Ocean Universitythe National Key Research Programs of China under contract Nos2016YFC1401407 and 2017YFA0604100the National Programme on Global Change and Air-Sea Interaction under contract Nos GASIIPOVAI-03 and GASI-IPOVAI-05the Innovation Group Project of Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)under contract No.311020004。
文摘In general,a mesoscale cyclonic(anticyclonic)eddy has a colder(warmer)core,and it is considered as a cold(warm)eddy.However,recently research found that there are a number of"abnormal"mesoscale cyclonic(anticyclonic)eddies associated with warm(cold)cores in the South China Sea(SCS).These"abnormal"eddies pose a challenge to previous works on eddy detection,characteristic analysis,eddy-induced heat and salt transports,and even on mesoscale eddy dynamics.Based on a 9-year(2000–2008)numerical modelling data,the cyclonic warm-core eddies(CWEs)and anticyclonic cold-core eddies(ACEs)in the SCS are analyzed.This study found that the highest incidence area of the"abnormal"eddies is the northwest of Luzon Strait.In terms of the eddy snapshot counting method,8620 CWEs and 9879 ACEs are detected,accounting for 14.6%and 15.8%of the total eddy number,respectively.The size of the"abnormal"eddies is usually smaller than that of the"normal"eddies,with the radius only around 50 km.In the generation time aspect,they usually appear within the 0.1–0.3 interval in the normalized eddy lifespan.The survival time of CWEs(ACEs)occupies 16.3%(17.1%)of the total eddy lifespan.Based on two case studies,the intrusion of Kuroshio warm water is considered as a key mechanism for the generation of these"abnormal"eddies near the northeastern SCS.
文摘北极海冰变化与冬季欧亚大陆气温异常变化存在密切联系,而冬季冷高压系统的频繁活动对于西伯利亚以及东亚地区降温产生直接影响,在“北极放大”以及未来北极海冰退缩情景下,西伯利亚近地面反气旋活动如何变化值得深入探究。本研究利用基于深度学习的Mask R-CNN反气旋客观识别算法对欧亚大陆冬季天气尺度反气旋进行识别,使用欧洲中期天气预报中心(European Centre for Medium-Range Weather Forecasts,ECMWF)ERA5再分析资料、美国国家海洋和大气管理局(National Oceanic and Atmospheric Administration,NOAA)OISST V2.1每日海冰密集度数据集以及MIROC6模式输出资料,进一步研究了在未来北极海冰迅速退缩的背景下,前期秋季海冰异常变化可能对反气旋和冷空气活动产生的影响及其机制。结果表明,1981-2022年秋季巴伦支海-卡拉海区域(Barents-Kara Sea,BKS)海冰指数减下降,而欧亚大陆中高纬度特别是西伯利亚区域的气温显著下降,冷空气质量异常堆积,反气旋活动携带的冷空气质量增多。进一步利用北极放大计划(Polar Amplification Model Intercomparison Project,PAMIP)中的模式资料,统计欧亚大陆反气旋在未来北极海冰较少情景下的活动变化规律,发现海冰减少条件下,西伯利亚区是欧亚大陆反气旋的主要影响和生消地之一,该区域反气旋具有局地活动特征,对准定常的西伯利亚冷高压以及冷池区冷空气积聚起重要促进作用。气温在欧亚大陆北边缘增高但在欧亚大陆中纬度呈显著下降特征,伴随着欧亚大陆大部分地区极寒天数增多。进一步研究发现秋季BKS海冰状况可作为前兆因子对后期冬季反气旋活动以及气温异常产生影响,该地区海冰状况引起区域位涡经向梯度显著降低,从而使上游东欧平原阻塞发生频率增大,有利于反气旋活动增强和冷空气的输送,促使东亚冬季寒冷趋势加剧。
