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Relationship between sea surface salinity and ocean circulation and climate change

Science China Earth Sciences 2019年第5期62卷 771-782页

作者： Yan DU yuhong zhang Jiancheng SHI State Key Laboratory of Tropical Oceanography South China Sea Institute of Oceanology Chinese Academy of Sciences University of Chinese Academy of Sciences State Key Laboratory of Remote Sensing Science Institute of Remote Sensing and Digital Earth Chinese Academy of Sciences

Based on Argo sea surface salinity(SSS) and the related precipitation(P), evaporation(E), and sea surface height data sets, the climatological annual mean and low-frequency variability in SSS in the global ocean and their relationship with ocean circulation and climate change were analyzed. Meanwhile, together with previous studies, a brief retrospect and prospect of seawater salinity were given in this work. Freshwater flux(E-P) dominated the mean pattern of SSS, while the dynamics of ocean circulation modulated the spatial structure and low-frequency variability in SSS in most regions. Under global warming, the trend in SSS indicated the intensification of the global hydrological cycle, and featured a decreasing trend at low and high latitudes and an increasing trend in subtropical regions. In the most recent two decades, global warming has slowed down, which is called the"global warming hiatus". The trend in SSS during this phase, which was different to that under global warming, mainly indicated the response of the ocean surface to the decadal and multi-decadal variability in the climate system, referring to the intensification of the Walker Circulation. The significant contrast of SSS trends between the western Pacific and the southeastern Indian Ocean suggested the importance of oceanic dynamics in the cross-basin interaction in recent decades. Ocean Rossby waves and the Indonesian Throughflow contributed to the freshening trend in SSS in the southeastern Indian Ocean, while the increasing trend in the southeastern Pacific and the decreasing trend in the northern Atlantic implied a long-term linear trend under global warming. In the future, higher resolution SSS data observed by satellites, together with Argo observations, will help to extend our knowledge on the dynamics of mesoscale eddies, regional oceanography, and climate change.

关键词： Sea surface salinity Ocean circulation Climate change Multi-scale interaction

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Numerical partitioning of components for four-modal sedimentary grain-size distribution based on gradient descent method

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Science China Earth Sciences 2014年第12期57卷 3097-3106页

作者： CHEN HaiBo zhang yuhong LIU Qiang Laboratory of Physical Oceanography Ocean University of China Guangzhou Institute of Geochemistry Chinese Academy of Sciences College of Engineering Ocean University of China

The gradient descent(GD)method is used to fit the measured data(i.e.,the laser grain-size distribution of the sediments)with a sum of four weighted lognormal *** method is calibrated by a series of ideal numerical *** numerical results indicate that the GD method not only is easy to operate but also could effectively optimize the parameters of the fitting function with the error decreasing *** method is applied to numerical partitioning of laser grain-size components of a series of Garzêloess samples and three bottom sedimentary samples of submarine turbidity currents modeled in an open channel laboratory *** overall fitting results are *** a new approach of data fitting,the GD method could also be adapted to solve other optimization problems.

关键词： nonlinear least squares data fitting gradient descent method mixture distribution of four lognormal components sediment grain-size

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Asymmetry of upper ocean salinity response to the Indian Ocean dipole events as seen from ECCO simulation

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Acta Oceanologica Sinica 2016年第7期35卷 42-49页

作者： zhang Ying DU Yan zhang yuhong GAO Shan State Key Laboratory of Tropical Oceanography South China Sea Institute of Oceanology Chinese Academy of Sciences Guangzhou 510301 China University of Chinese Academy of Sciences Beijing 100049 China Key Laboratory of Ocean Circulation and Waves Institute of Oceanology Chinese Academy of Sciences Qingdao 266071 China

The interannual variability of salinity and associated ocean dynamics in the equatorial Indian Ocean is analyzed using observations and numerical simulations by the Estimating the Circulation and Climate of the Ocean （ECCO） model. The results show that salinity anomalies in the upper ocean are asymmetrically associated with the Indian Ocean dipole （IOD） events, with stronger response during their positive phases. Further investigations reveal that zonal currents along the equator, the Wyrtki jets, dominate the salinity transport. During the positive IOD events, the Wyrtld jets have stronger westward anomalies. The positive skewness of the IOD explains that the amplitude of the anomalous Wyrtld jets is stronger in the positive IOD events than that in the negative events.

关键词： Wyrtld jets salinity transport Indian Ocean dipole asymmetry

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Dark spatial solitons sequence in the biased centrosymmetric photorefractive crystal

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Optoelectronics Letters 2022年第10期18卷 601-605页

作者： zhang yuhong JIA Xinjuan College of Opto-Electronic Engineering Xi’an Technological UniversityXi’an710021China College of Freshmen Xi’an Technological UniversityXi’an710021China

We theoretically investigate the evolution of dark screening spatial solitons originating from the quadratic electro-optic effect in biased centrosymmetric photorefractive(CP) crystal by using beam propagation method(BPM). The results indicate that the multiple dark solitons sequence can be obtained in the CP crystal with the odd or even initial conditions. If the initial width of the dark notch is smaller, only a fundamental soliton or a Y-junction soliton pair is generated. When the initial width of the dark notch and the bias electric field are increased, the multiple dark spatial solitons sequence is formed, which realized a progressive transition from a low-order soliton to a higher-order solitons sequence in both odd and even conditions. The solitons characteristic is similar to that of screening solitons in the non-centrosymmetric photorefractive(NCP) crystals.

关键词： conditions solitons soliton

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Effects of multiple dynamic processes on chlorophyll variation in the Luzon Strait in summer 2019 based on glider observation

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Journal of Oceanology and Limnology 2023年第2期41卷 469-481页

作者： Xiangpeng WANG Yan DU yuhong zhang Tianyu WANG State Key Laboratory of Tropical Oceanography South China Sea Institute of OceanologyChinese Academy of SciencesGuangzhou 510301China College of Marine Science University of Chinese Academy of SciencesBeijing 100049China Guangdong Key Laboratory of Ocean Remote Sensing South China Sea Institute of OceanologyChinese Academy of SciencesGuangzhou 510301China

Luzon Strait is the main channel connecting the South China Sea(SCS)and the western Pacific,with complex atmospheric and oceanic dynamic *** on 44 days of glider measurements and satellite observations,we investigated the temporal and vertical variations of chlorophyll-a(Chl-a)concentration in the Luzon Strait from July 25 to September 6,*** Chl a was mainly distributed above 200 m and concentrated in the subsurface chlorophyll maximum(SCM)*** depth of SCM ranged between 50 m and 110 m,and the magnitude of SCM varied from 0.42 mg/m3 to 1.12 mg/*** variation of Chl a was identified with three stages responding to different dynamic *** the influence of Kuroshio intrusion,the SCM depth sharply deepened,and its magnitude decreased in Stage ***,a prominent Chl-a bloom was observed in the SCM layer from August 6 to August *** Chl-a bloom in Stage 2 was related to the influence of a cyclonic eddy,which uplifted of the thermocline and thus the deep *** Stage 3,prolonged heavy rainfall in the northeastern SCS resulted in a significant salinity decrease in the upper *** convergence of upper water deepened the thermocline and the mixed ***,the Chl a decreased in the SCM layer but increased in the surface *** particular,a typhoon passed through the Luzon Strait on August 24,which induced the Chl a increase in the upper 50 ***,there was little change in the depth-integrated Chl a(0-200 m),indicating that the Chl a increase in the surface layer was likely associated with physical entrainment of SCM caused by strong mixing,rather than the phytoplankton bloom in the upper water *** gliders provide frequent autonomous observations that help us understand the regional ocean’s complex dynamic processes and biological responses.

关键词： Luzon Strait glider observations chlorophyll a Kuroshio cyclonic eddy typhoon

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Range-angle-dependent beamforming for FDA-MIMO radar using oblique projection

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Science China(Information Sciences) 2022年第5期65卷 223-241页

作者： Lan LAN Guisheng LIAO Jingwei XU Shengqi ZHU yuhong zhang National Key Laboratory of Radar Signal Processing Xidian University School of Electronic Engineering Xidian University

Frequency diverse array(FDA)-multiple-input and multiple-output(MIMO) radar is characterized with a range-angle-dependent transceive beampattern by introducing incremental frequencies among the transmit array elements and separating the transmitted waveforms with matched filtering in the receiver. In this respect, the paper aims to control the range-angle-dependent transceive beampattern for FDA-MIMO radar by designing the weight vector according to the desired response. At the design stage, the weight vectors to control the beampattern responses of different regions are devised by performing the orthogonal decomposition technique. Then, a filtering matrix using the oblique projection operator is constructed to filter the weight vectors for different regions, where two iterative algorithms are developed either considering concurrent or successive control of multiple regions. In such a way, a desired range-angle-dependent transceive beampattern is formed with simultaneously broadened nulls and a flat-top mainlobe. At the analysis stage,the method has been applied to interference mitigation in FDA-MIMO radar, where the mismatch exists both in the sidelobes and mainlobe. Simulated and measured results are provided to corroborate the effectiveness of the proposed methods.

关键词： FDA-MIMO radar range-angle-dependent beamforming weight vector orthogonal decomposition oblique projection interference mitigation

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Effects of tide-surge interactions on storm surges along the coast of the Bohai Sea, Yellow Sea, and East China Sea

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Science China Earth Sciences 2016年第6期59卷 1308-1316页

作者： XU JunLi zhang yuhong CAO AnZhou LIU Qiang LV XianQing Key Laboratory of Physical Oceanography (Ocean University of China) Ministry of Education Ocean University of China College of Engineering Ocean University of China

A two-dimensional coupled tide-surge model was used to investigate the effects of tide-surge interactions on storm surges along the coast of the Bohai Sea, Yellow Sea, and East China Sea. In order to estimate the impacts of tide-surge interactions on storm surge elevations, Typhoon 7203 was assumed to arrive at 12 different times, with all other conditions remaining constant. This allowed simulation of tide and total water levels for 12 separate cases. Numerical simulation results for Yingkou, Huludao, Shijiusuo, and Lianyungang tidal stations were analyzed. Model results showed wide variations in storm surge elevations across the 12 cases. The largest difference between 12 extreme storm surge elevation values was of up to 58 cm and occurred at Yingkou tidal station. The results indicate that the effects of tide-surge interactions on storm surge elevations are very significant. It is therefore essential that these are taken into account when predicting storm surge elevations.

关键词： Storm surges Astronomical tides Tide-surge interactions Typhoon 7203 Coupled tide-surge model

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Multi-view Feature Learning for the Over-penalty in Adversarial Domain Adaptation

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Data Intelligence 2024年第1期6卷 183-200页

作者： yuhong zhang Jianqing Wu Qi zhang Xuegang Hu School of Computer and Information Engineering Hefei University of TechnologyHefei 230601China Key Laboratory of Knowledge Engineering with Big Data(Hefei University of Technology) The Ministry of Education of ChinaHefei 230009China

Domain adaptation aims to transfer knowledge from the labeled source domain to an unlabeled target domain that follows a similar but different ***,adversarial-based methods have achieved remarkable success due to the excellent performance of domain-invariant feature presentation ***,the adversarial methods learn the transferability at the expense of the discriminability in feature representation,leading to low generalization to the target *** this end,we propose a Multi-view Feature Learning method for the Over-penalty in Adversarial Domain ***,multi-view representation learning is proposed to enrich the discriminative information contained in domain-invariant feature representation,which will counter the over-penalty for discriminability in adversarial ***,the class distribution in the intra-domain is proposed to replace that in the inter-domain to capture more discriminative information in the learning of transferrable *** experiments show that our method can improve the discriminability while maintaining transferability and exceeds the most advanced methods in the domain adaptation benchmark datasets.

关键词： domain adaptation adversarial learning multi-view learning

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Sentiment Classification Based on Piecewise Pooling Convolutional Neural Network

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Computers, Materials & Continua 2018年第8期56卷 285-297页

作者： yuhong zhang Qinqin Wang Yuling Li Xindong Wu School of Computer Science and Information Engineering Hefei University of Technology485 Danxia RoadShushan DistrictHefei230009China School of Computing and Informatics University of Louisiana at Lafayette222 James R.Oliver HallLafayetteLouisiana 70504USA

Recently,the effectiveness of neural networks,especially convolutional neural networks,has been validated in the field of natural language processing,in which,sentiment classification for online reviews is an important and challenging *** convolutional neural networks extract important features of sentences without local features or the feature ***,these models do not perform well,especially for transition *** this end,we propose a Piecewise Pooling Convolutional Neural Network(PPCNN)for sentiment ***,with a sentence presented by word vectors,convolution operation is introduced to obtain the convolution feature map ***,these vectors are segmented according to the positions of transition words in ***,the most significant feature of each local segment is extracted using max pooling mechanism,and then the different aspects of features can be ***,the relative sequence of these features is ***,after processed by the dropout algorithm,the softmax classifier is trained for sentiment *** results show that the proposed method PPCNN is effective and superior to other baseline methods,especially for datasets with transition sentences.

关键词： Sentiment classification convolutional neural network piecewise pooling feature extract

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Mobility of rhenium and selenium during chemical weathering and their implication for petrogenic organic carbon oxidation

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Science China Earth Sciences 2024年第3期67卷 740-750页

作者： yuhong zhang Jin WANG Yuanxin QU Chao ZHU zhangdong JIN State Key Laboratory of Loess and Quaternary Geology Institute of Earth EnvironmentChinese Academy of SciencesXi'an 710061China University of Chinese Academy of Sciences Beijing 100049China Xi'an Institute for Innovative Earth Environment Research Xi'an 710061China Institute of Global Environmental Change Xi'an Jiaotong UniversityXi'an 710049China

The oxidative weathering of petrogenic organic carbon(OC_(petro)) is an important source of carbon dioxide(CO_(2)) into the atmosphere on geological timescales and significantly influences the carbon cycle and global climate change. However, at present, a robust proxy to assess OC_(petro)oxidation is lacking. Riverine rhenium(Re) has emerged as a potential proxy to trace OC_(petro)oxidation, but little is known about Re sources and its relationship with OC_(petro)oxidation. To better understand the robustness of this proxy, we analyzed a shale weathering profile from the early Cambrian Shuijingtuo Formation in Chengkou County, Chongqing City, to address the mobility of Re and selenium(Se) and their relationship with the oxidation of OC_(petro)by analyses of the elemental variation and sequential extraction. The results showed that the chemical index of alteration(CIA)increases from the fresh bedrock to the weathered sections, indicating enhanced weathering intensity. Based on the sequential extraction and mass transfer coefficients(τ), Re and Se mainly exist in the organic phase of shale and are paired lost with OC_(petro) during weathering, with no obvious correlation with sulfide minerals. Furthermore, the different proportions of Re and Se loss with OC_(petro) loss can be attributed to their different geochemical behaviors during weathering. Our study supports Re as a robust proxy to trace OC_(petro) oxidation, whereas Se is the potential one. In the future, combined studies on various sedimentary rock profiles with catchment basins are needed to determine the sources of riverine Re and Se and their relationships with OC_(petro) oxidation.

关键词： Rhenium and selenium Shale Mobility OC_(petro) Chemical weathering

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