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Study on the propagation velocity of internal solitary waves in the Andaman Sea using Terra/Aqua-MODIS remote sensing images

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Journal of Oceanology and Limnology 2021年第6期39卷 2195-2208页

作者： Lina SUN Jie ZHANG junmin meng First Institute of Oceanography Ministry of Natural ResourcesQingdao 266061China Technology Innovation Center for Ocean Telemetry Ministry of Natural ResourcesQingdao 266061China

The Andaman Sea has been a classic study region for internal solitary waves(ISWs)for several decades,and extraordinarily large ISWs are characteristic of the Andaman Sea in the Indian *** paper presents results on the estimation of the propagation velocity of ISWs in the Andaman Sea that were tracked using 195 image pairs acquired by MODIS National Aeronautics and Space Administration(NASA)Terra/Aqua satellites between January 2014 and December 2018.A total of 562 ISWs were identified during the period,and the results of the propagation velocity distribution of ISWs in the Andaman Sea are *** estimated propagation velocity of ISWs agrees well with the theoretical results derived from the Korteweg-de Vries(KdV)equation using monthly climatology stratification data and local *** ISW propagation velocity decreases as they propagate from deep to shallow water;the maximum propagation velocity of 3.27 m/s was estimated on the western side of the Nicobar Islands and minimum speed of 0.54 m/s occurred in the shallow water region of the southeastern Andaman *** results show that the ISW propagation characteristics differ in the northern,central,and southern regions of the Andaman *** the northern Andaman Sea,the velocity of ISWs propagating westward was greater than that of ISWs propagating eastward at the same water *** the central Andaman Sea,the propagation velocity of the ISWs differed over a small area at a depth of 2500 m,and the velocity of ISWs in the deep mixing layer in winter was higher than that in the shallow mixing layer in *** variations in ISW propagation velocity were analyzed in the southern Andaman Sea,and the velocity of ISWs differed greatly in shallow water and was not significantly different in deep *** depth and monthly stratification play vital roles in controlling the phase speed of ISWs in the Andaman *** study will provide a basis for the propagation and prediction of ISWs in the Anda

关键词： internal solitary waves propagation velocity remote sensing Andaman Sea

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Underwater topography detection of Shuangzi Reefs with SAR images acquired in different time

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Acta Oceanologica Sinica 2007年第1期26卷 48-54页

作者： YANG Jungang ZHANG Jie meng junmin Institute of Oceanology Chinese Academy of Sciences Qingdao 266071 China Graduate School Chinese Academy of Sciences Beijing 100039 China First Institute of Oceanography State Oceanic Administration Qingdao 266061 China Key Laboratory of Marine Science and Numerical Modeling of State Oceanic Administration First Institute of Oceanography State Oceanic Administration Qingdao 266061 China

Imaging mechanism of underwater topography by SAR and a underwater topography SAR detection model built on the theory of underwater topography detection with SAR image presented by Yuan Yeli are used to detect the underwater topography of Shuangzi Reefs in the Nansha Islands with three scenes of SAR images acquired in different time. Detection results of three SAR images are compared with the chart topography and the detection errors are analyzed. Underwater topography detection experiments of Shuangzi Reefs show that the detection model is practicable. The detection results indicate that SAR images acquired in different time also can be used to detect the underwater topography, and the detection results are affected by the ocean conditions in the SAR acquiring time.

关键词： Shuangzi Reefs underwater topography SAR image topography detection

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A study of the spatial-temporal distribution and propagation characteristics of internal waves in the Andaman Sea using MODIS

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Acta Oceanologica Sinica 2019年第7期38卷 121-128页

作者： Lina Sun Jie Zhang junmin meng First Institute of Oceanography Ministry of Natural Resources

This paper describes investigations of the internal waves in the Andaman Sea using Moderate Resolution Imaging Spectroradiometer(MODIS)imagery over the period of June 2010 to May *** of the spatial and temporal distribution,generation sources and propagation characteristics of internal waves are *** statistical analysis shows that internal waves can be observed in almost the entire area of the Andaman *** internal waves are observed in the northern,central and southern regions of the Andaman Sea.A significant number of internal waves between 7°N and 9°N in the East Indian Ocean are also *** waves can be observed year-round in the Andaman Sea,while most of internal waves are observed between February and April,with a maximum frequency of 15.03%in *** seasonal distribution of the internal waves shows that the internal waves have mostly been observed in the dry season(February to April),and fewer internal waves are observed in the rainy season(May to October).The double peak distribution for the occurrence frequency of internal waves is *** respect to the lunar influence,more internal waves are observed after the spring tide,which implies the spring tide may play an important role in internal wave generation in the Andaman *** sources of internal waves are explored based on the propagation characteristics of internal *** results indicate that six sources are located between the Andaman Islands and the Nicobar Islands,and one is located in the northern Andaman *** regions with active internal wave phenomenon in the Andaman Sea were presented during the MODIS survey,and the propagation speed of internal waves calculated based on the semidiurnal generation period is smaller than the results acquired from pairs of the images with short time intervals.

关键词： internal waves remote sensing Andaman Sea MODIS

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Study of the ability of SWOT to detect sea surface height changes caused by internal solitary waves

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Acta Oceanologica Sinica 2024年第5期43卷 54-64页

作者： Hao Zhang Chenqing Fan Lina Sun junmin meng First Institute of Oceanography Ministry of Natural ResourcesQingdao 266061China Technology Innovation Center for Ocean Telemetry Ministry of Natural ResourcesQingdao 266061China College of Oceanography and Space Informatics China University of Petroleum(Huadong)Qingdao 266580China

Surface Water and Ocean Topography(SWOT)is a next-generation radar altimeter that offers high resolution,wide swath,imaging *** has provided free public data worldwide since December *** paper aims to preliminarily analyze the detection capabilities of the Ka-band radar interferometer(KaRIn)and Nadir altimeter(NALT),which are carried out by SWOT for internal solitary waves(ISWs),and to gather other remote sensing images to validate SWOT *** effectively detects ISW surface features and generates surface height variation maps reflecting the modulations induced by ***,its swath width does not completely cover the entire wave packet,and the resolution of L2/L3 level products(about 2 km)cannot be used to identify ISWs with smaller ***,significant wave height(SWH)images exhibit blocky structures that are not suitable for ISW studies;sea surface height anomaly(SSHA)images display systematic leftright *** optimize this imbalance using detrending methods;however,more precise treatment should commence with L1-level *** analysis based on L3-level SSHA data indicates that the average SSHA variation induced by ISWs ranges from 10 cm to 20 *** disturbed by ISWs record unusually elevated SWH and SSHA values,rendering the data unsuitable for analysis and necessitating targeted corrections in future retracking *** the normalized radar cross section,Ku-band and four-parameter maximum likelihood estimation retracking demonstrated greater sensitivity to minor changes in the sea surface,making them more suitable for ISW *** conclusion,SWOT demonstrates outstanding capabilities in ISW detection,significantly advancing research on the modulation of the sea surface by ISWs and remote sensing imaging mechanisms.

关键词： internal solitary waves Surface Water and Ocean Topography(SWOT) Ka-band radar interferometer(KaRIn) Nadir altimeter(NALT) sea surface height anomaly(SSHA) normalized radar cross section(NRCS)

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Detection of ocean internal waves based on Faster R-CNN in SAR images

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Journal of Oceanology and Limnology 2020年第1期38卷 55-63页

作者： BAO Sude meng junmin SUN Lina LIU Yongxin Inner Mongolia University Hohhot 010021China First Institute of Oceanography Ministry of Natural ResourcesQingdao 266061China

Ocean internal waves appear as irregular bright and dark stripes on synthetic aperture radar(SAR)remote sensing *** internal waves detection in SAR images consequently constituted a difficult and popular research *** this paper,ocean internal waves are detected in SAR images by employing the faster regions with convolutional neural network features(Faster R-CNN)framework;for this purpose,888 internal wave samples are utilized to train the convolutional network and identify internal *** experimental results demonstrate a 94.78%recognition rate for internal waves,and the average detection speed is 0.22 s/*** addition,the detection results of internal wave samples under different conditions are *** paper lays a foundation for detecting ocean internal waves using convolutional neural networks.

关键词： ocean internal waves faster regions with convolutional neural network features (Faster R-CNN) convolutional neural network synthetic aperture radar (SAR) image region proposal network (RPN)

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An improved frequency shift method for ATI-SAR flat earth phase removal

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Acta Oceanologica Sinica 2019年第8期38卷 94-100页

作者： Yubin Zhang Jie Zhang junmin meng Chenqing Fan First Institute of Oceanography Ministry of Natural Resources Qingdao 266061 China College of Information Science and Engineering Ocean University of China Qingdao 266100 China

An improved frequency shift method is proposed to remove the flat earth phase in ATI-SAR ocean surface motion detection in this study. First, two conventional flat earth effect removal methods(i.e., the frequency shift method and the orbital parameter method) are introduced and compared. Then, two improvements to frequency shift method are suggested. In the first improvement, the phase diagram is divided into several sub-blocks to calculate the phase fringe frequency. In the second improvement, a function between the phase of land regions and position is fitted to correct the residual flat earth phase based on the phase of the land regions that tend toward zero in an along-track interferogram. It is found that the improved frequency shift method is greatly improved;and it agrees well with the orbital parameter method, and achieves similar accuracy.

关键词： flat earth phase ATI-SAR frequency shift orbital parameter

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A wave energy resource assessment in the China's seas based on multi-satellite merged radar altimeter data

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Acta Oceanologica Sinica 2015年第3期34卷 115-124页

作者： WAN Yong ZHANG Jie meng junmin WANG Jing College of Information Science and Engineering Ocean University of China First Institute of Oceanography State Oceanic Administration College of Information and Control Engineering China University of Petroleum

Wave energy resources are abundant in both offshore and nearshore areas of the China＇s seas. A reliable assessment of the wave energy resources must be performed before they can be exploited. First, for a water depth in offshore waters of China, a parameterized wave power density model that considers the effects of the water depth is introduced to improve the calculating accuracy of the wave power density. Second, wave heights and wind speeds on the surface of the China＇s seas are retrieved from an AVISO multi-satellite altim-eter data set for the period from 2009 to 2013. Three mean wave period inversion models are developed and used to calculate the wave energy period. Third, a practical application value for developing the wave energy is analyzed based on buoy data. Finally, the wave power density is then calculated using the wave field data. Using the distribution of wave power density, the energy level frequency, the time variability indexes, the to-tal wave energy and the distribution of total wave energy density according to a wave state, the offshore wave energy in the China＇s seas is assessed. The results show that the areas of abundant and stable wave energy are primarily located in the north-central part of the South China Sea, the Luzon Strait, southeast of Taiwan in the China＇s seas; the wave power density values in these areas are approximately 14.0–18.5 kW/m. The wave energy in the China’s seas presents obvious seasonal variations and optimal seasons for a wave energy utilization are in winter and autumn. Except for very coastal waters, in other sea areas in the China＇s seas, the energy is primarily from the wave state with 0.5 m≤Hs≤4 m, 4 s≤Te≤10 s whereHs is a significant wave height andTe is an energy period; within this wave state, the wave energy accounts for 80% above of the total wave energy. This characteristic is advantageous to designing wave energy convertors （WECs）. The practical application value of the wave energy is higher which can be

关键词： China's seasmulti-satellite merged altimeter data wave energy resources assessment wave power density

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Shenzhou-4 spaceborne altimeter waveform processing and significant wave height retrieval

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Acta Oceanologica Sinica 2006年第3期25卷 40-47页

作者： JI Yonggang ZHANG Jie ZHANG Youguang meng junmin Institute of Oceanology Chinese Academy of Sciences Qingdao 266071 China Graduate School of Chinese Academy of Sciences Beijing 100039 China First Institute of Oceanography State Oceanic Administration Qingdao 266061 China National Satellite Ocean Application Service Beijing 100081 China

The Shenzhou -4 spaceborne （SZ -4） altimeter waveforms were processed, and then the significant wave heights （SWH） was retrieved on the basis of waveform fitting and waveform retracking. Waveforms processing includes the waveform ls averaging, the elimination of thermal noise and the waveforms normalization. Double peaks were found on each SZ - 4 waveform, and it was pointed out that the region of waveforms with the second peak is abnormal and its effects on the whole waveform in the waveform fit should be taken into consideration. To obtain the width of the waveform leading-edge, a method was proposed to find the starting point of waveform, and the half-power point of waveform was found by retracking the waveform. The normalized wavefornis were fitted with the Haynes model by using the weighting least square fit method. Then the selections of the weighting coefficients and their effects on significant wave hight retrieving were discussed, and the optimal five-region weighting method was proposed. At last, the SWH data of SZ -4 altimeter retrieved by using the proposed method were compared with those of ERS -2 and Jason - 1 altimeter, and it was concluded that the SZ -4 altimeter can detect significant wave height.

关键词： SZ-4 spaeeborne altimeter significant wave height double peaks waveform retraeking waveform fit

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Assessment of C-band compact polarimetry SAR for sea ice classification

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Acta Oceanologica Sinica 2016年第5期35卷 79-88页

作者： ZHANG Xi ZHANG Jie LIU Meijie meng junmin First Institute of Oceanography State Oceanic Administration College of Physics Qingdao University

The C-band synthetic aperture radar（SAR） data from the Bohai Sea of China, the Labrador Sea in the Arctic and the Weddell Sea in the Antarctic are used to analyze and discuss the sea ice full polarimetric information reconstruction ability under compact polarimetric modes. The type of compact polarimetric mode which has the highest reconstructed accuracy is analyzed, along with the performance impact of the reconstructed pseudo quad-pol SAR data on the sea ice detection and sea ice classification. According to the assessment and analysis, it is recommended to adopt the CTLR mode for reconstructing the polarimetric parameters σ_（HH）~0,σ_（VV）~0, H and α,while for reconstructing the polarimetric parameters σ_（HV）~0, ρ_（H-V）, λ_1 and λ_2, it is recommended to use the π/4 ***, it is recommended to use the π/4 mode in studying the action effects between the electromagnetic waves and sea ice, but it is recommended to use the CTLR mode for studying the sea ice classification.

关键词： sea ice SAR compact polarimetry sea ice classification assessment and analysis

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Study on the amplitude inversion of internal waves at Wenchang area of the South China Sea

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Acta Oceanologica Sinica 2016年第7期35卷 14-19页

作者： ZHANG Xudong WANG Jing SUN Lina meng junmin College of Information and Engineering Ocean University of China First Institute of Oceanography State Oceanic Administration

The field experiment is conducted from April 16, 2005 to July 20, 2005 at Wenchang area east of Hainan Island （19~35＇N, l12~E） of China. Internal wave packets are observed frequently with thermistor chains during the experiment. Meanwhile, internal waves are also detected from a synthetic aperture radar （SAR） image on June 19, 2005 and several other moderate-resolution imaging spectroradiometer （MODIS） images near a mooring position. The distance between the positive and negative peaks induced by the internal wave can be obtained from satellite images. Combined with remote sensing images and in situ data, a new method to inverse the amplitude of the internal wave is proposed based on a corrected nonlinear Schr6dinger （NLS） equation. Two relationships are given between the peak-to-peak distance and the characteristic wavelength of the internal wave for different nonlinear and dispersion coefficients. Based on the satellite images, the amplitude inversion of the internal waves are carried out with the NLS equation as well as the KdV equation. The calculated amplitudes of the NLS equation are close to the observation amplitude which promise the NLS equation a reliable method.

关键词： internal wave amplitude inversion nonlinear SchrSdinger equation remote sensing image Wenchang area

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