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Validation of Chinese HY-2 satellite radar altimeter significant wave height

Acta Oceanologica Sinica 2015年第5期34卷 60-67页

作者： YE Xiaomin LIN Mingsen XU Ying college of Information Science and Engineering Ocean University of China State Key Laboratory of Satellite Ocean Environment Dynamics Second Institute of OceanographyState Oceanic Administration National Satellite Ocean Application Service State Oceanic Administration Key Laboratory of space Ocean Remote Sensing and Application State Oceanic Administration

Chinese Haiyang-2（HY-2） satellite is the first Chinese marine dynamic environment satellite. The dual-frequency （Ku and C band） radar altimeter onboard HY-2 has been working effective to provide operational significant wave height （SWH） for more than three years （October 1, 2011 to present）.We validated along-track Ku-band SWH data of HY-2 satellite against National Data Buoy Center （NDBC） in-situ measurements over a time period of three years from October 1, 2011 to September 30, 2014, the root mean square error （RMSE） and mean bias of HY-2 SWH is 0.38 m and （-0.13±0.35） m, respectively. We also did cross validation against Jason-2 altimeter SWH data, the RMSE and the mean bias is 0.36m and （-0.22±0.28） m, respectively. In order to compare the statistical results between HY-2 and Jason-2 satellite SWH data, we validated the Jason-2 satellite radar altimeter along-track Ku-band SWH data against NDBC measurements using the same method. The results demonstrate the validation method in this study is scientific and the RMSE and mean bias of Jason-2 SWH data is 0.26 m and （0.00±0.26） m, respectively. We also validated both HY-2 and Jason-2 SWH data every month, the mean bias of Jason-2 SWH data almost equaled to zero all the time, while the mean bias of HY-2 SWH data was no less than -0.31m before April 2013 and dropped to zero after that time. These results indicate that the statistical results for HY-2 altimeter SWH are reliable and HY-2 altimeter along-track SWH data were steady and of high quality in the last three years. The results also indicate that HY-2 SWH data have greatly been improved and have the same accuracy with Jason-2 SWH data after April, 2013. SWH data provided by HY-2 satellite radar altimeter are useful and acceptable for ocean operational applications.

关键词： significant wave height validation Chinese HY-2 satellite radar altimeter

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Dynamical analysis of mesoscale eddy-induced ocean internal waves using linear theories

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Acta Oceanologica Sinica 2008年第3期27卷 60-69页

作者： XU Qing ZHENG Quanan LIN Hui LIU Yuguang SONG Y Tony YUAN Yeli Institute of space and Earth Information Science The Chinese University of Hong Kong Hong Kong China Department of Atmospheric and Oceanic Science University of Maryland College Park Maryland USA Physical oceanography Laboratory Ocean University of China Qingdao 266100 China Jet Propulsion Laboratory California Institute of Technology Pasadena California USA Key Laboratory for Marine Science and Numerical Modeling of State Oceanic Administration First Institute of Oceanography State Oceanic Administration Qingdao 266061 China

This study aims to explore generation mechanisms of the ocean internal wave using the dynamical analysis methods based on linear theories. Historical cruise measurements and recent synthetic aperture radar （SAR） observations of mesoscale eddies with diameter of several tens of kilometers to hundreds of kilometers show that the internal wave packets with wavelength of hundreds of meters to kilometer exist inside the mesoscale eddies. This coexistence phenomenon and inherent links between the two different scale processes are revealed in the solutions of governing equations and boundary conditions for the internal wave disturbance with a horizontally slowly variable amplitude in a cylindrical coordinate system. The theoretical solutions indicate that the instability of eddy current field provides the dynamical mechanism to internal wave generation. The derived dispersion relation indicates that the internal wave propagation is modified by the eddy current field structure. The energy equation of the internal waves clearly shows the internal wave energy increment comes from the eddy. The theoretical models are used to explain the observation of the mesoscale eddy-induced internal waves off the Norwegian coast. The two-dimensional waveform solution of the anticyclonic eddy-induced internal wave packet appears as ring-shaped curves, which contains the typical features of eddy stream lines. The comparison of theoretical solutions to the structure of the internal wave packets on SAR image shows a good agreement on the major features.

关键词： ocean internal waves mesoscale eddy current field instability SAR image

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A Corresponding Lie Algebra of a Reductive homogeneous Group and Its Applications

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Communications in Theoretical Physics 2015年第5期63卷 535-548页

作者：张玉峰吴立新芮文娟 college of Sciences China University of Mining and Technology School of Environment Science and Spatial informatics China University of Mining and Technology

With the help of a Lie algebra of a reductive homogeneous space G/K, where G is a Lie group and K is a resulting isotropy group, we introduce a Lax pair for which an expanding （2＋1）-dimensional integrable hierarchy is obtained by applying the binormial-residue representation （BRR） method, whose ttamiltonian structure is derived from the trace identity for deducing （2＋1）-dimensional integrable hierarchies, which was proposed by Tu, et al. We further consider some reductions of the expanding integrable hierarchy obtained in the paper. The first reduction is just right the （2＋1 ）-dimensionai AKNS hierarchy, the second-type reduction reveals an integrable coupling of the （2＋1）-dimensional AKNS equation （also called the Davey-Stewartson hierarchy）, a kind of （2＋1）-dimensionai Sehr6dinger equation, which was once reobtained by Tu, Feng and Zhang. It is interesting that a new （2＋1）-dimensional integrable nonlinear coupled equation is generated from the reduction of the part of the （2＋1）-dimensional integrable coupling, which is further reduced to the standard （2＋1）-dimensionaJ diffusion equation along with a parameter. In addition, the well-known （1＋1）-dimensional AKNS hierarchy, the （1＋1）-dimensional nonlinear Schr6dinger equation are all special cases of the （2＋1）-dimensional expanding integrable hierarchy. Finally, we discuss a few discrete difference equations of the diffusion equation whose stabilities are analyzed by making use of the yon Neumann condition and the Fourier method. Some numerical solutions of a special stationary initial value problem of the （2＋1）-dimensional diffusion equation are obtained and the resulting convergence and estimation formula are investigated.

关键词： (2+1)-dimensional hierarchy Lie algebra Hamiltonian structure

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Study of the propagation direction of the internal waves in the South China Sea using satellite images

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Acta Oceanologica Sinica 2013年第5期32卷 42-50页

作者： WANG Juan HUANG Weigen YANG Jingsong ZHANG Huaguo ZHENG Gang college of Information Science and Engineering Ocean University of China State Key Laboratory of Satellite Ocean Environment Dynamics Second Institute of OceanographyState Oceanic Administration

Internal wave propagation carries considerable vertical shear which can lead to turbulence and mixing. Based on the analysis of more than 2 500 synthetic aperture radar （SAR） and optical satellite images, the in- ternal wave propagation in the whole South China Sea was investigated systematically. The results show that （1） in the northeastern South China Sea, most internal waves propagate westward from the Luzon Strait and are diffracted by coral reefs near the Dongsha Islands. Some impinge onto the shelf and a few are reflected; （2） in the northwestern South China Sea, most internal waves are generated at the shelf and propagate northwestward or westward to the coast; （3） in the western South China Sea, most internal waves propagate westward to the Vietnamese coast, except a few propagate southward to the deep sea; and （4） in the southern South China Sea, most internal waves propagate southwestward to the coast. Some prop- agate southeastward to the coast of Kalimantan Island, and a few propagate southeastward because of the influence of the Mekon~ River.

关键词： remote sensing internal wave propagation South China Sea satellite images

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A VGGNet-based correction for satellite altimetry-derived gravity anomalies to improve the accuracy of bathymetry to depths of 6500 m

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Acta Oceanologica Sinica 2024年第1期43卷 112-122页

作者： Xiaolun Chen Xiaowen Luo Ziyin Wu Xiaoming Qin Jihong Shang Huajun Xu Bin Li Mingwei Wang Hongyang Wan Key Laboratory of Submarine Geosciences Second Institute of OceanographyMinistry of Natural ResourcesHangzhou 310012China Ocean college Zhejiang UniversityZhoushan 316021China Key Laboratory of Ocean space Resources Management Technology Marine Academy of ZhejiangHangzhou 310012China School of oceanography Shanghai Jiao Tong UniversityShanghai 200240China School of Civil Engineering and Architectures Zhejiang University of Science and TechnologyHangzhou 310023China National Center for Archaeology Beijing 100013China

Understanding the topographic patterns of the seafloor is a very important part of understanding our *** the science involved in bathymetric surveying has advanced much over the decades,less than 20%of the seafloor has been precisely modeled to date,and there is an urgent need to improve the accuracy and reduce the uncertainty of underwater survey *** this study,we introduce a pretrained visual geometry group network(VGGNet)method based on deep *** apply this method,we input gravity anomaly data derived from ship measurements and satellite altimetry into the model and correct the latter,which has a larger spatial coverage,based on the former,which is considered the true value and is more *** obtaining the corrected high-precision gravity model,it is inverted to the corresponding bathymetric model by applying the gravity-depth *** choose four data pairs collected from different environments,i.e.,the Southern Ocean,Pacific Ocean,Atlantic Ocean and Caribbean Sea,to evaluate the topographic correction results of the *** experiments show that the coefficient of determination(R~2)reaches 0.834 among the results of the four experimental groups,signifying a high *** standard deviation and normalized root mean square error are also evaluated,and the accuracy of their performance improved by up to 24.2%compared with similar research done in recent *** evaluation of the R^(2) values at different water depths shows that our model can achieve performance results above 0.90 at certain water depths and can also significantly improve results from mid-water depths when compared to previous ***,the bathymetry corrected by our model is able to show an accuracy improvement level of more than 21%within 1%of the total water depths,which is sufficient to prove that the VGGNet-based method has the ability to perform a gravity-bathymetry correction and achieve outstanding results.

关键词： gravity anomaly bathymetry inversion VGGNet multibeam sonar satellite altimetry

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High-resolution simulation of upper-ocean submesoscale variability in the South China Sea:Spatial and seasonal dynamical regimes

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Acta Oceanologica Sinica 2022年第7期41卷 26-41页

作者： Haijin Cao Xin Meng Zhiyou Jing Xiaoxiao Yang Key Laboratory of Marine Hazards Forecasting of Ministry of Natural Resources Hohai UniversityNanjing210024China college of oceanography Hohai UniversityNanjing210024China State Key Laboratory of Tropical oceanography South China Sea Institute of OceanologyChinese Academy of SciencesGuangzhou510301China

Submesoscale processes in marginal seas usually have complex generating mechanisms,highly dependent on the local background flow and *** numerical study investigates the spatial and seasonal differences of submesoscale activities in the upper ocean of the South China Sea(SCS)and the different dynamical regimes for *** spatial and seasonal variations of vertical vorticity,horizontal convergence,lateral buoyancy gradient,and strain rate are analyzed to compare the submesoscale phenomenon within four sub-regions,the northern region near the Luzon Strait(R1),the middle ocean basin(R2),the western SCS(R3),and the southern SCS(R4).The results suggest that the SCS submesoscale processes are highly heterogeneous in space,with different seasonalities in each *** submesoscale activities in the northern sub-regions(R1,R2)are active in winter but weak in summer,while there appears an almost seasonal anti-phase in the western region(R3)compared to R1 and ***,no clear seasonality of submesoscale features is shown in the southern region(R4).Further analysis of Ertel potential vorticity reveals different generating mechanisms of submesoscale processes in different *** analyses also show the vertical extent of vertical velocity and the role of monsoon in generating submesoscale activities in the upper ocean of *** these results suggest that the sub-regions have different regimes for submesoscale processes,e.g.,Kuroshio intrusion(R1),monsoon modulation(R2),frontal effects(R3),topography wakes(R4).

关键词： submesoscale South China Sea high-resolution simulation spatial difference seasonal difference

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Time correction of the ocean bottom seismometers deployed at the southwest Indian ridge using ambient noise cross-correlation

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Acta Oceanologica Sinica 2018年第5期37卷 39-46页

作者： LIU Yunlong LIU Cai TAO Chunhui YAO Huajian QIU Lei WANG Ao RUAN Aiguo WANG Hanchuang ZHOU Jianping LI Huaiming DONG Chuanwan college of Geoexploration Science and Technology Jilin University Key Laboratory of Submarine Geosciences Second Institute of OceanographyState Oceanic Administration Laboratory of Seismology and Physics of Earth's Interior School of Earth and Space Sciences University of Science and Technology of China Institute of Geophysics and Geomatics China University of Geosciences School of Earth Sciences Zhejiang University

Seismic monitoring using ocean bottom seismometers（OBS） is an efficient method for investigating earthquakes in mid-ocean ridge far away from land. Clock synchronization among the OBSs is difficult without direct communication because electromagnetic signals cannot propagate efficiently in water. Time correction can be estimated through global positioning system（GPS） synchronization if clock drift is linear before and after the deployment. However, some OBSs in the experiments at the southwest Indian ridge（SWIR） on the Chinese DY125-34 cruise had not been re-synchronized from GPS after recovery. So we attempted to estimate clock drift between each station pairs using time symmetry analysis（TSA） based on ambient noise cross-correlation. We tested the feasibility of the TSA method by analyzing daily noise cross-correlation functions（NCFs） that extract from the data of another OBS experiment on the Chinese DY125-40 cruise with known clock drift and the same deployment site. The results suggest that the NCFs＇ travel time of surface wave between any two stations are symmetrical and have an opposite growing direction with the date. The influence of different band-pass filters,different components and different normalized methods was discussed. The TSA method appeared to be optimal for the hydrophone data within the period band of 2–5 s in dozens of km-scale interstation distances. A significant clock drift of ~2 s was estimated between OBSs sets through linear regression during a 108-d deployment on the Chinese cruise DY125-34. Time correction of the OBS by the ambient noise cross-correlation was demonstrated as a practical approach with the appropriate parameters in case of no GPS re-synchronization.

关键词： clock drift cross-correlation ambient noise OBS

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Enhanced Full-Resolution Residual Network for Image Super-Resolution

Enhanced Full-Resolution Residual Network for Image Super-Re...

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第40届中国控制会议

作者： Jiaoyue Li Lifei Zhao Qianqian Shao Weifeng Liu Kai Zhang Bao-Di Liu college of oceanography and space informatics China University of Petroleum (East China) college of Control Science and Engineering China University of Petroleum (East China) college of Petroleum Engineering China University of Petroleum (East China)

Convolutional neural network（CNN） has played a critical role in promoting image super-resolution（SR） performance,and researchers have proposed various models in recent years. Although these models can improve the resolution of the image,the sharpness is not ideal. In this paper, We modify a semantic segmentation network: Full-Resolution Residual Network（FRRN）and propose an Enhanced Full-Resolution Residual Network for Image Super-Resolution（EFRN） model to improve the image clarity. Our network mainly applies a long skip connection to the direct fusion of low-level and high-level features. Besides, we also introduce the attention mechanism into the model to enhance the network’s repair capability. Moreover, experimental results confirm that EFRN has achieved better accuracy and visual effects than state-of-the-art methods.

关键词： Enhanced Full-Resolution Residual Block Spatial Attention Channel Attention Image Super-Resolution

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An experimental study on fire characteristics of urban complex underground space based on BIM

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CAAI Transactions on Intelligence Technology 2023年第4期8卷 1403-1414页

作者： Jinrong Cui Hao Mei Haosen Sun Ye Jingqi Wei Hu Yong Xu college of Mathematics and informatics(college of Software Engineering) South China Agricultural UniversityGuangzhouChina The University of Manchester ManchesterUK Harbin Institute of Technology(Shenzhen) ShenzhenChina

Compared with the space on the ground,if there is a fire in the urban complex underground space,the loss will be greatly *** addition,the complex underground space is usually connected with other large space areas and densely *** a fire occurs in the complex underground space,it will cause huge property losses and *** order to reduce the risk of fire,it is necessary to deeply understand the development rules and characteristics of fire in the complex underground space of the *** article has mainly carried on the following work:(I)A particularly complex model of the multi‐storey subway station was *** this basis,three groups of comparative experiments were conducted to study the effects of fire power,fire location and smoke control system on fire development,and the conclusion that fire location is the most important factor for fire development was obtained;(II)In order to explore the entire space fire and the local space fire,CFD(Computational Fluid Dynamics)is used to build a large‐size fire model and a small‐size fire model respectively;(III)Multiple detector data as temperature slices were built,and it is expected to make full use of the simulation data to deduce the important index of fire location in the early stage of *** of the works in this paper will provide reference experimental data for the prevention and firefighting of a sudden fire in the complex underground space.

关键词： fire simulation underground multi‐storey subway station urban complex underground space

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A study of internal solitary waves observed on the continental shelf in the northwestern South China Sea

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Acta Oceanologica Sinica 2010年第3期29卷 18-25页

作者： XU Zhenhua YIN Baoshu HOU Yijun FAN Zhisong Antony K LIU Institute of Oceanology Chinese Academy of Sciences Qingdao 266071 China Key Laboratory of Ocean Circulation and Waves （KLOCAW） Chinese Academy of Sciences Qingdao 266071 China college of Physical and Environmental oceanography Ocean University of China Qingdao 266100 China Ocean Sciences Branch NASA Goddard Space Flight Center Greenbelt Maryland USA

Based on in-situ time series data from the acoustic Doppler current profiler （ADCP） and thermistor chain in Wenchang area, a sequence of internal solitary wave （ISW） packets was observed in September 2005, propagating northwest on the continental shelf of the northwestern South China Sea （SCS）. Corresponding to different stratification of the water column and tidal condition, both elevation and depression ISWs were observed at the same mooring location with amplitude of 35 m and 25 m respectively in different days. Regular arrival of the remarkable ISW packets at approximately the diurnal tidal period and the dominance of diurnal internal waves in the study area, strongly suggest that the main energy source of the waves is the diurnal tide. Notice that the wave packets were all riding on the troughs and shoulders of the internal tides, they were probably generated locally from the shelf break by the evolution of the internal tides due to nonlinear and dispersive effects.

关键词： elevation internal solitary waves diurnal internal tide northwestern South China Sea

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