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Subthermocline eddies carrying the Indonesian Throughflow water observed in the southeastern tropical Indian Ocean

Acta Oceanologica Sinica 2023年第5期42卷 1-13页

作者： Guangbing Yang Quanan Zheng Xuejun Xiong First Institute of Oceanography and Key Laboratory of Marine Science and Numerical ModelingMinistry of Natural ResourcesQingdao 266061China laboratory for Regional Oceanography and numerical modeling Pilot National Laboratory for Marine Science and Technology(Qingdao)Qingdao 266237China shandong key laboratory of marine science and numerical modeling Qingdao 266061China Department of Atmospheric and Oceanic science University of MarylandCollege Park 20742USA

We observed a subthermocline eddy(STE)with a cold and fresh core during an observation cruise along a transect of 10°S in the southeastern tropical Indian Ocean(SETIO)in December 2017.The vertical scale,speed radius,and maximum swirl velocity of the STE were about 200 m,55 km,and 0.5 m/s,respectively.The mean Rossby number and Burger number of the STE were then estimated to be about−0.7 and 2.4,indicating the STE was a submesoscale coherent vortex.The STE core water had characteristics of the Indonesian Throughflow(ITF)water and was distinct from that of surrounding areas.By examining Argo float data,another STE was well captured by five successive profiles of the same Argo float.Both STEs showed significant temperature and salinity anomalies at theσ0=26.0-26.5 kg/m3 surfaces.With the assumption that the low-salinity ITF water parcels could be carried only by surface eddies and the STEs,the Argo profiles,which detected low-salinity ITF water and were located outside a surface eddy,were believed to be inside an STE and were used to analyze the distribution,origin,and generation mechanism of the STE.The results suggested that the STEs carrying ITF water may be generated under topography-current interaction at the eastern coastal waters or under front-induced subduction in the area away from coastal waters.Those STEs may be widely distributed in the SETIO and may play a role in ITF water parcel transport.

关键词： subthermocline eddy southeastern tropical Indian Ocean Indonesian Throughflow submesoscale coherent vortex

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Variable projection algorithms with sparse constraint for separable nonlinear models

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Control Theory and Technology 2024年第1期22卷 135-146页

作者： Hui-Lang Xu Guang-Yong Chen Si-Qing Cheng Min Gan Jing Chen College of Computer and Data science Fuzhou UniversityFuzhou350116FujianChina Fujian key laboratory of Network Computing and Intelligent Information Processing Fuzhou UniversityFuzhou350116FujianChina key laboratory of Intelligent Metro of Universities in Fujian Fuzhou UniversityFuzhou350116FujianChina Engineering Research Center of Big Data Intelligence Ministry of EducationFuzhou UniversityFuzhou350116FujianChina School of science Jiangnan UniversityWuxi214122JiangsuChina

Separable nonlinear models are widely used in various fields such as time series analysis, system modeling, and machine learning, due to their flexible structures and ability to capture nonlinear behavior of data. However, identifying the parameters of these models is challenging, especially when sparse models with better interpretability are desired by practitioners. Previous theoretical and practical studies have shown that variable projection (VP) is an efficient method for identifying separable nonlinear models, but these are based on \(L_2\) penalty of model parameters, which cannot be directly extended to deal with sparse constraint. Based on the exploration of the structural characteristics of separable models, this paper proposes gradient-based and trust-region-based variable projection algorithms, which mainly solve two key problems: how to eliminate linear parameters under sparse constraint;and how to deal with the coupling relationship between linear and nonlinear parameters in the model. Finally, numerical experiments on synthetic data and real time series data are conducted to verify the effectiveness of the proposed algorithms.

关键词： Variable projection(VP) Non-smooth constraint Separable nonlinear models

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Vertical velocity and transport in the South China Sea

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Acta Oceanologica Sinica 2022年第7期41卷 13-25页

作者： Yaohua Zhu Dingqi Wang Yonggang Wang Shujiang Li Tengfei Xu Zexun Wei First Institute of Oceanography and Key Laboratory of Marine Science and Numerical ModelingMinistry of Natural ResourcesQingdao266061China laboratory for Regional Oceanography and numerical modeling Pilot National Laboratory for Marine Science and Technology(Qingdao)Qingdao266237China shandong key laboratory of marine science and numerical modeling Qingdao266061China College of Oceanic and Atmospheric sciences Ocean University of ChinaQingdao266100China

Deep water in the South China Sea is renewed by the cold and dense Luzon Strait overflow.However,from where and how the deep water upwells is poorly understood yet.Based on the Hybrid Coordinate Ocean Model reanalysis data,vertical velocity is derived to answer these questions.Domain-integrated vertical velocity is of two maxima,one in the shallow water and the other at depth,and separated by a layer of minimum at the bottom of the thermocline.Further analysis shows that this two-segmented vertical transport is attributed to the vertical compensation of subsurface water to the excessive outflow of shallow water and upward push of the dense Luzon Strait overflow,respectively.In the abyssal basin,the vertical transport increases upward from zero at the depth of 3500–4000 m and reaches a maximum of 1.5×10^(6) m^(3)/s at about 1500 m.Deep water upwells mainly from the northeastern and southwestern ends of the abyssal basin and off the continental slopes.To explain the upward velocity arising from slope breaks,a possible mechanism is proposed that an onshore velocity component can be derived from the deep western boundary current above steep slopes under bottom friction.

关键词： vertical velocity vertical transport Luzon Strait overflow South China Sea

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Estimating the evolution of sea state non-Gaussianity based on a phase-resolving model

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Journal of Oceanology and Limnology 2022年第5期40卷 1909-1923页

作者： Xingjie JIANG Tingting ZHANG Dalu GAO Daolong WANG Yongzeng YANG First Institute of Oceanography and Key Laboratory of Marine Science and Numerical ModelingMinistry of Natural ResourcesQingdao 266061China laboratory for Regional Oceanography and numerical modeling Pilot National Laboratory for Marine Science and Technology(Qingdao)Qingdao 266237China shandong key laboratory of marine science and numerical modeling Qingdao 266061China Ocean University of China College of Oceanic and Atmospheric SciencesQingdao 266071China

The occurrence of rogue waves is closely related to the non-Gaussianity of sea states,and this non-Gaussianity can be estimated using corresponding two-dimensional wave spectra.This paper presents an approach to non-Gaussianity estimation based on a phase-resolving model called the high-order spectral method(HOSM).Based on numerous HOSM simulations,a set of precalculated non-Gaussianity indicators was established that could be applied to real sea states without any calibration of spectral shapes.With a newly developed extraction approach,the indicators for given two-dimensional wave spectra could then be conveniently extracted from the precalculated dataset.The feasibility of the newly developed approach in a real wave environment is verified.Using the estimation approach,phase-resolved non-Gaussianity can now be illustrated throughout the evolution of sea states of interest,not just at a few specific times;and the level of non-Gaussianity at any time in a duration can be identified according to the statistics(e.g.,quantities)of the phase-resolved indicators,that are obtained throughout the duration concerned.

关键词： rogue wave sea state non-Gaussianity high-order spectral method spectral geometry wave-wave nonlinearity

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A hybrid physics-informed data-driven neural network for CO_(2) storage in depleted shale reservoirs

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Petroleum science 2024年第1期21卷 286-301页

作者： Yan-Wei Wang Zhen-Xue Dai Gui-Sheng Wang Li Chen Yu-Zhou Xia Yu-Hao Zhou College of Construction Engineering Jilin UniversityChangchun130026JilinChina Institute of Intelligent Simulation and Early Warning for Subsurface Environment Jilin UniversityChangchun130026JilinChina School of Energy Resources China University of GeosciencesBeijing100083China Department of Safety Environmental Protection and Quality ManagementShengli OilfieldSinopecDongying257000ShandongChina key laboratory of Thermo-Fluid science and Engineering of MOE School of Energy and Power EngineeringXi'an Jiaotong UniversityXi'an710049ShaanxiChina College of Computer science and Technology China University of Petroleum(East China)Qingdao266580ShandongChina Department of Physics University of FribourgFribourg1700Switzerland

To reduce CO_(2) emissions in response to global climate change,shale reservoirs could be ideal candidates for long-term carbon geo-sequestration involving multi-scale transport processes.However,most current CO_(2) sequestration models do not adequately consider multiple transport mechanisms.Moreover,the evaluation of CO_(2) storage processes usually involves laborious and time-consuming numerical simulations unsuitable for practical prediction and decision-making.In this paper,an integrated model involving gas diffusion,adsorption,dissolution,slip flow,and Darcy flow is proposed to accurately characterize CO_(2) storage in depleted shale reservoirs,supporting the establishment of a training database.On this basis,a hybrid physics-informed data-driven neural network(HPDNN)is developed as a deep learning surrogate for prediction and inversion.By incorporating multiple sources of scientific knowledge,the HPDNN can be configured with limited simulation resources,significantly accelerating the forward and inversion processes.Furthermore,the HPDNN can more intelligently predict injection performance,precisely perform reservoir parameter inversion,and reasonably evaluate the CO_(2) storage capacity under complicated scenarios.The validation and test results demonstrate that the HPDNN can ensure high accuracy and strong robustness across an extensive applicability range when dealing with field data with multiple noise sources.This study has tremendous potential to replace traditional modeling tools for predicting and making decisions about CO_(2) storage projects in depleted shale reservoirs.

关键词： Deep learning Physics-informed data-driven neural network Depleted shale reservoirs CO_(2)storage Transport mechanisms

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Spatial-temporal shifting patterns and in situ conservation of spotted seal(Phoca largha)populations in the Yellow Sea ecoregion

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Integrative Zoology 2024年第2期19卷 307-318页

作者： Hongfei ZHUANG Fei SHAO Chao ZHANG Wancai XIA Shouqiang WANG Fangyuan QU Zongling WANG Zhichuang LU Linlin ZHAO Zhaohui ZHANG First Institute of Oceanography Ministry of Natural ResourcesQingdaoChina Department of Natural Resources of shandong Province Shandong Forestry Protection and Development Service CenterJinanChina National Park(Protected Areas)Development Center National Forestry and Grassland AdministrationBeijingChina College of Life science China West Normal UniversityNanchongChina Liaoning Ocean and Fisheries science Research Institute DalianChina

Understanding the habitat shifting pattern is a prerequisite for implementing in situ conservation of migratory species.Spotted seals(Phoca largha)inhabiting the Yellow Sea ecoregion(YSE)comprise a small population with independent genes and represent a charismatic flagship species in this region.However,this population has declined by 80%since the 1940s,and increased support from the countries around the YSE is urgently needed to address the potential local extinction risk.A time-series niche model and life-history weighted systematic conservation planning were designed on the basis of a satellite beacon tracking survey(2010–2020)of the YSE population.The results showed clustering and spreading shifting patterns during the breeding and migratory seasons,respectively.The closed-loop migration route formed in the YSE indicated that this population might be geographically isolated from populations in other breeding areas around the world.The conservation priority area(CPA),with an area of 19632 km^(2)(3.58%of the total YSE area),was the most effective response to the potential in situ risk.However,nearly 80%of the CPA was exposed outside the existing marine protected areas(MPAs).Future establishment of MPAs in China should strategically consider the conservation gap identified herein,and it is recommended for Korea’s closed fishing season to be spatially set in the western Korean Peninsula from May to August.This study also exemplified that the lack of temporal information would lead to the dislocation of niche modeling for migratory species represented by spotted seals.Attention should be paid to protecting small and migratory populations in marine biodiversity conservation planning.

关键词： conservation priority area marine protected area migration seasonal management spotted seal

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Variability of the deep South China Sea circulation derived from HYCOM reanalysis data

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Acta Oceanologica Sinica 2022年第7期41卷 54-64页

作者： Yaohua Zhu Guojiao Cao Yonggang Wang Shujiang Li Tengfei Xu Dingqi Wang Fei Teng Zexun Wei First Institute of Oceanography and Key Laboratory of Marine Science and Numerical ModelingMinistry of Natural ResourcesQingdao266061China laboratory for Regional Oceanography and numerical modeling Pilot National Laboratory for Marine Science and Technology(Qingdao)Qingdao266237China shandong key laboratory of marine science and numerical modeling Qingdao266061China Navigation College Jiangsu Maritime InstituteNanjing211100China College of Oceanic and Atmospheric sciences Ocean University of ChinaQingdao266100China

This study aims to investigate variability of the deep South China Sea(SCS)circulation using the Hybrid Coordinate Ocean Model(HYCOM)global reanalysis product.The results reveal that annual cycle is a dominant component in the deep SCS circulation.Meanwhile,the boundary circulation strength is the weakest in January and peaks between June and September.The eastern and southern boundary currents strengthen/weaken one to three months earlier than that in the western and northern boundaries.Vector Empirical Orthogonal Functions(VEOF)analysis results reveal that semiannual and intraseasonal fluctuations are significant components,of which the spatial patterns are mainly confined in the northern and western boundary areas as well as the southwestern sub-basin.Wavelet analysis results show the strength of significant fluctuation varies year to year.Trend analysis results indicate a decadal weakening in the deep SCS circulation.An anomalous anticyclonic circulation,50–70 km apart from the slope break,tends to weaken the cyclonic boundary circulation in the western and northern boundaries as well as the southwestern sub-basin.This trend is similar to the observed decadal weakening in the North Atlantic deep circulation.Thus,the findings of this study reveal that the variation of the deep SCS circulation has a remarkable response to the climate change.The mechanisms responsible for the variation are worth pursuing if more observations are available.

关键词： South China Sea variability of deep circulation HYCOM data VEOF analysis wavelet analysis

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Observation and analysis of the influence of wind waves on air-sea momentum fluxes

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science China Earth sciences 2023年第7期66卷 1547-1555页

作者： Sheng CHEN Yuhuan XUE Baoshan YANG Yongqing YU Fangli QIAO First Institute of Oceanography Ministry of Natural ResourcesQingdao 266061China key laboratory of marine sciences and numerical modeling Ministry of Natural ResourcesQingdao 266061China key laboratory of marine sciences and numerical modeling Shandong ProvinceQingdao 266061China Shengli Oilfield Branch SinopecDongying 257000China

Due to the long-standing lack of understanding the role of wind waves on wind stress at moderate to high wind speeds,a high-frequency turbulence observation system is used in this study to obtain air-sea momentum flux data under pure wind wave conditions based on the tower-based marine meteorological observation platform in the southern Bohai Sea.Moreover,the modulation of wind waves on wind stress under wind speeds greater than 10 m s^(–1)is analyzed.The results indicated that the wind wave states caused by winds from the northwest and northeast are different under the influence of cold air,resulting in different wind stresses and drag coefficients.The wind stress increases with an increasing wind speed,reaching its maximum value when the northwest wind is nearly 20 m s^(–1),while the extreme value of the drag coefficient is basically the same when the northwest wind speed is the maximum and the northeast wind wave significant wave height is the maximum.The drag coefficient increases with an increasing wind speed within the range of 10–15 m s^(–1),reaching saturation at 15 m s^(–1).The critical wind speed is smaller than other observed results.Further analysis showed that wind-induced turbulent stress deviates from the observed values,and the degree of deviation depends on the wind speed and wave state,with a greater deviation caused by strong winds and waves.The wave-induced stress can correct the negative deviation between wind-induced turbulent stress and the observed value,and the drag coefficient calculated based on the modified wind stress tends to be close to the observed value overall.

关键词： Tower-based platform in the Bohai Sea Moderate to high wind speed Pure wind waves Wind stress Wave-induced stress

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Identification of Antarctic minke and killer whales with passive acoustic monitoring in Prydz Bay, Antarctica

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Journal of Oceanology and Limnology 2022年第2期40卷 485-495页

作者： Ying JIANG Lian-Gang LÜ Zongwei LIU Chunmei YANG Jingsong GUO First Institute of Oceanography Ministry of Natural ResourcesQingdao 266061China laboratory for Regional Oceanography and numerical modeling Pilot National Laboratory for Marine Science and Technology(Qingdao)Qingdao 266237China key laboratory of marine science and numerical modeling Ministry of Natural ResourcesQingdao 266061China

Although four species of odontocete and four species of baleen whale have been recorded in Prydz Bay,their vocalizations have been rarely investigated.Underwater vocalizations were recorded during March 2017 in Prydz Bay,Antarctica.Bio-duck sounds,downsweeps,inverted“u”shape signals,whistles,pulsed sounds,and broadband clicks were recorded.Bio-duck sounds and downsweeps were associated with Antarctic minke whales(Balaenoptera bonaerensis)based on visual observations.Similarities between inverted“u”shape signals,biphonic calls,and clicks with vocalizations previously described for killer whales(Orcinus orca)lead us believe the presence of Antarctic killer whales.According to sound structures,signal characteristics,and recording location,Antarctic type C killer whales were the most probable candidates to produce these detected calls.These represent the fi rst detection of inverted“u”shape signals in Antarctic waters,and the fi rst report of Antarctic killer whale in Prydz Bay based on passive acoustic monitoring.The co-existence of Antarctic minke and killer whales may imply that minke whales can detect diff erences between the sounds of mammal-eating and fi sh-eating killer whales.Our descriptions of these underwater vocalizations contribute to the limited body of information regarding the distribution and acoustic behavior of cetaceans in Prydz Bay.

关键词： passive acoustic monitoring inverted“u”shaped signal killer whale Antarctic minke whales Prydz Bay type C

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Spatiotemporal characteristics of water exchange between the Andaman Sea and the Bay of Bengal

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Acta Oceanologica Sinica 2024年第5期43卷 1-15页

作者： Yihao Wang Feng Zhou Xueming Zhu Ruijie Ye Yingyu Peng Zhentao Hu Haoran Tian Na Li Ocean College Zhejiang UniversityZhoushan 316021China State key laboratory of Satellite Ocean Environment Dynamics Second Institute of OceanographyMinistry of Natural ResourcesHangzhou 310012China Observation and Research Station of Yangtze River Delta marine Ecosystems Ministry of Natural ResourcesZhoushan 316022China Southern marine science and Engineering Guangdong laboratory(Zhuhai) Zhuhai 519080China School of Oceanography Shanghai Jiao Tong UniversityShanghai 200240China School of marine sciences Sun Yat-sen UniversityZhuhai 519080China

A high-resolution customized numerical model is used to analyze the water transport in the three major water passages between the Andaman Sea(AS)and the Bay of Bengal,i.e.,the Preparis Channel(PC),the Ten Degree Channel(TDC),and the Great Channel(GC),based on the daily averaged simulation results ranging from 2010 to 2019.Spectral analysis and Empirical Orthogonal Function(EOF)methods are employed to investigate the spatiotemporal variability of the water exchange and controlling mechanisms.The results of model simulation indicate that the net average transports of the PC and GC,as well as their linear trend,are opposite to that of the TDC.This indicates that the PC and the GC are the main inflow channels of the AS,while the TDC is the main outflow channel of the AS.The transport variability is most pronounced at surface levels and between 100 m and 200 m depth,likely affected by monsoons and circulation.A 182.4-d semiannual variability is consistently seen in all three channels,which is also evident in their second principal components.Based on sea level anomalies and EOF analysis results,this is primarily due to equatorial winds during the monsoon transition period,causing eastward movement of Kelvin waves along the AS coast,thereby affecting the spatiotemporal characteristics of the flow in the AS.The first EOF of the PC flow field section shows a split at 100 m deep,likely due to topography.The first EOF of the TDC flow field section is steady but has potent seasonal oscillations in its time series.Meanwhile,the first EOF of the GC flow field section indicates a stable surface inflow,probably influenced by the equatorial Indian Ocean’s eastward current.

关键词： Andaman Sea water exchange Regional Ocean modeling Systems(ROMS) Kelvin waves spatiotemporal characteristics

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