首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到10条相似文献,搜索用时 109 毫秒
1.
Mesoscale eddies, which are mainly caused by baroclinic effects in the ocean, are common oceanic phenomena in the Northwest Pacific Ocean and play very important roles in ocean circulation, ocean dynamics and material energy transport. The temperature structure of mesoscale eddies will lead to variations in oceanic baroclinity, which can be reflected in the sea level anomaly (SLA). Deep learning can automatically extract different features of data at multiple levels without human intervention, and find the hidden relations of data. Therefore, combining satellite SLA data with deep learning is a good way to invert the temperature structure inside eddies. This paper proposes a deep learning algorithm, eddy convolution neural network (ECN), which can train the relationship between mesoscale eddy temperature anomalies and sea level anomalies (SLAs), relying on the powerful feature extraction and learning abilities of convolutional neural networks. After obtaining the temperature structure model through ECN, according to climatic temperature data, the temperature structure of mesoscale eddies in the Northwest Pacific is retrieved with a spatial resolution of 0.25° at depths of 0–1 000 m. The overall accuracy of the ECN temperature structure is verified using Argo profiles at the locations of cyclonic and anticyclonic eddies during 2015–2016. Taking 10% error as the acceptable threshold of accuracy, 89.64% and 87.25% of the cyclonic and anticyclonic eddy temperature structures obtained by ECN met the threshold, respectively.  相似文献   

2.
两个西边界流延伸体区域中尺度涡统计特征分析   总被引:3,自引:2,他引:1  
黑潮和湾流是世界大洋中最典型的两支西边界流,黑潮延伸体(Kuroshio Extention,KE)和湾流延伸体(Gulf Stream Extention,GSE)区域中尺度涡活动十分活跃。本文综合利用卫星高度计资料和Argo浮标资料,对KE和GSE区域中尺度涡的表层特征及其对温盐影响进行了统计研究和对比分析。结果表明:黑潮和湾流主轴附近为涡旋频率的高值区,主轴南北两侧分别以气旋涡和反气旋涡数量占多,主轴附近的涡旋强度明显大于其他区域;两个区域的涡旋以西向移动为主,气旋涡和反气旋涡都具有向南(赤道)偏离的趋势;两个区域的涡旋数量都以夏、秋季较多,涡旋强度都在春、夏季较大,且GSE区域涡旋强度明显大于KE区域;气旋涡(反气旋涡)引起内部明显的温度负(正)异常,KE区域气旋涡(反气旋涡)内部呈"负-正"("正-负")上下层相反的盐度异常分布,GSE区域气旋涡(反气旋涡)在各层呈现较为一致的盐度负(正)异常;两个区域中尺度涡对温盐场的平均影响深度可达1 000×104 Pa以上。  相似文献   

3.
基于南海东北部1998~2019年的多源卫星遥感数据和风场再分析数据, 较系统地分析了南海东北部涡旋内部叶绿素a浓度的分布特征, 通过量化统计和涡心坐标系参数合成等方法探究了中尺度涡对叶绿素a浓度变化的影响规律及潜在机制。结果表明: (1)南海东北部约有60%的中尺度涡旋内部存在叶绿素a浓度增加和减少的现象。(2)南海东北部中尺度涡内部叶绿素a扰动受到涡旋抽吸和涡致Ekman抽吸机制的共同调控, 其中约有38% (39%)的暖(冷)涡内涡旋抽吸的贡献更大, 21% (24%)的暖(冷)涡内涡致Ekman抽吸的贡献更大。(3)南海东北部中尺度涡生命周期内的海表叶绿素a浓度变化存在显著的阶段性差异, 在冷暖涡的生成期, 涡旋抽吸的作用更为显著, 而在冷暖涡的顶峰和消亡期, 涡致Ekman抽吸的作用更为明显。上述研究结果有助于理解南海东北部初级生产力对中尺度涡的响应过程与机理, 对认识海洋物理-生物耦合过程具有一定的参考价值和研究意义。  相似文献   

4.
Repeated hydrographic casts, mooring time series and satellite sea surface temperature collected during the CANALES experiment (1996–98) are used to describe the thermohaline circulation in the Balearic Channels (western Mediterranean) and to analyze its variability. Mass transports are estimated by inverse calculations. The role played by each channel in the meridional water exchange is clarified: the Ibiza Channel funnels southward cool, saline, northern waters whereas the Mallorca Channel appears as the preferred route for the northward progression of warm, fresh, southern waters. A neat interannual trend is revealed by the continuous decrease of the amount of Western Mediterranean Intermediate Waters (WIW) brought by the Northern Current, reflecting the increase in temperature of the winter mixed layer in the northern Mediterranean that occurred each year between 1996 and 1998. A clear seasonal signal was also seen in the transport of the Northern Current which decreased from 1 to 1.4 Sv in winter to < 0.5 Sv in summer. The current intensified again in fall. A number of mesoscale eddies, from 20 to 70 km in size, most of them anticyclonic vortex eddies were brought by the unstable Northern Current, these eddies strongly perturbed the water exchange in the Ibiza Channel forcing retroflections of northern waters back to the north-east into the Balearic Current. These eddies either stayed stalled for several months in the Gulf of Valencia to the north of the channel, or were slowly funnelled southward through the channel narrows. A decreasing trend was observed in the mesoscale activity of the Northern Current between 1996 and 1998. Conversely, large, anticyclonic eddies, 150-km diameter, progressively invaded the Algerian Basin to the south of the channels in 1997–98 and forcing northward inflows (up to 0.75 Sv) of fresh and warm waters of Atlantic origin (AW) into the Mallorca Channel. The marked interannual differences observed in both northern and southern eddy activity may be linked to the interannual variability of the large scale thermohaline circulation.  相似文献   

5.
南印度洋中尺度涡统计特征及三维合成结构研究   总被引:2,自引:2,他引:0  
南印度洋是海洋中尺度涡的多发区域。本文利用卫星高度计资料及Argo浮标资料,对南印度洋(10°~35°S, 50°~120°E)区域中尺度涡的分布、表观特征等进行了统计分析,采用合成方法,构建了该区域中尺度涡的三维温盐结构。结果表明,涡旋频率呈明显的纬向带状分布,在18°~30°S存在一个明显的涡旋频率带状高值区;涡旋半径具有由南至北逐渐增大的趋势;长周期涡旋在其生命周期内,半径、涡动能、涡能量密度、涡度等性质均经历了先增大而后减小的过程;涡旋以西向运动为主,在经向上移动距离较小,长周期气旋(反气旋)涡具有明显的偏向极地(赤道)移动的倾向;涡旋平均移动速度为5.9 cm/s,速度大小大致沿纬向呈带状分布。在混合层以下,气旋涡(反气旋涡)内部分别呈现明显的温度负(正)异常,且分别存在两个位温负(正)异常的冷(暖)核结构;气旋涡(反气旋涡)整体上呈现"正-负"("负-正")上下层相反的盐度异常结构。中尺度涡对温盐的平均影响深度可达1 000×104 Pa以上。  相似文献   

6.
We use a 9-km pan-Arctic ice–ocean model to better understand the circulation and exchanges in the Bering Sea, particularly near the shelf break. This region has, historically, been undersampled for physical, chemical, and biological properties. Very little is known about how water from the deep basin reaches the large, shallow Bering Sea shelf. To address this, we examine here the relationship between the Bering Slope Current and exchange across the shelf break and resulting mass and property fluxes onto the shelf. This understanding is critical to gain insight into the effects that the Bering Sea has on the Arctic Ocean, especially in regard to recent indications of a warming climate in this region. The Bering Sea shelf break region is characterized by the northwestward-flowing Bering Slope Current. Previously, it was thought that once this current neared the Siberian coast, a portion of it made a sharp turn northward and encircled the Gulf of Anadyr in an anticyclonic fashion. Our model results indicate a significantly different circulation scheme whereby water from the deep basin is periodically moved northward onto the shelf by mesoscale processes along the shelf break. Canyons along the shelf break appear to be more prone to eddy activity and, therefore, are associated with higher rates of on-shelf transport. The horizontal resolution configured in this model now allows for the representation of eddies with diameters greater than 36 km; however, we are unable to resolve the smaller eddies.  相似文献   

7.
Using the mesoscale eddy trajectory atlas product derived from satellite altimeter data from 1993 to 2016, this study analyzes statistical characteristics and seasonal variability of mesoscale eddies in the Banda Sea of the Indonesian seas. The results show that there were 147 mesoscale eddies that occurred in the Banda Sea, of which 137 eddies were locally generated and 10 originated from outside. The total numbers of cyclonic eddies (CEs, clockwise) and anticyclonic eddies (AEs, anticlockwise) are 76 and 71, respectively. Seasonally, the number of CEs (AEs) is twice larger than the number of AEs (CEs) in winter (summer). In winter, CEs are distributed in the southern and AEs in the northern basins, respectively, but the opposite thing occurs in summer, i.e., the polarities of mesoscale eddies observed at the same location reverse seasonally. The mechanisms of polarity distribution reversal (PDR) of mesoscale eddies are examined with reanalysis data of ocean currents and winds. The results indicate that the basin-scale vorticity, wind stress curl, and the meridional shear of zonal current reverse seasonally, which are favorable to the PDR of mesoscale eddies. The possible generation mechanisms of mesoscale eddies include direct wind forcing, barotropic and baroclinic instabilities, of which the direct wind forcing should play the dominant role.  相似文献   

8.
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, 8 620 CWEs and 9 879 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.  相似文献   

9.
建立了一个描述中尺度涡的新的非线性方程,然后利用变分原理研究了孤立涡旋的Liapunov稳定性,指出反气旋和气旋涡都是稳定的。数值计算结果发现在β效应的作用下这些涡旋都向西移动而不存在向南的移动,然而在反气旋涡的上游存在一个孤立地形(例如海山)的话,孤立地形会使反气旋涡向南移动,而且移动的轨迹取决于孤立地形的位置。当两个反气旋涡同时存在并发生相互作用时,上游孤立地形使这两个反气旋涡产生弱合并并出现弱分离。而且孤立地形的位置对这两个涡的移动和旋转有重要影响。  相似文献   

10.
针对海洋中尺度涡的检测与参数提取问题,本文使用中尺度涡SAR图像数据集,提出基于深度学习的EddyYolo目标检测模型进行中尺度涡的涡旋中心和涡旋水平尺度的多目标检测,并且提取涡心位置和涡旋水平半径等参数.实验结果表明:本文提出的EddyYolo模型实现了涡旋中心和涡旋水平尺度的多目标检测,检测准确率达到94%.在此基础上,结合二维高斯涡模型和三维中尺度涡模型,本文提出了基于卫星遥感与声学对中尺度涡的联合建模方法.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号