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Influence of Coriolis Parameter Variation on Langmuir Turbulence in the Ocean Upper Mixed Layer with Large Eddy Simulation

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Advances in Atmospheric Sciences 2022年第9期39卷 1487-1500页

作者： Dongxiao WANG Guojing LI Lian SHEN yeqiang shu State Key Laboratory of Tropical Oceanography South China Sea Institute of OceanologyChinese Academy of SciencesGuangzhou 510301China Department of Mechanical Engineering and St.Anthony Falls Laboratory University of MinnesotaMinneapolisMinnesota 55455USA Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou) Guangzhou 510301China

Langmuir turbulence is a complex turbulent process in the ocean upper mixed *** Coriolis parameter has an important effect on Langmuir turbulence through the Coriolis-Stokes force and Ekman effect,however,this effect on Langmuir turbulence has not been systematically ***,the impact of the Coriolis parameter on Langmuir turbulence with a change of latitude(LAT)from 20°N to 80°N is studied using a non-hydrostatic large eddy simulation model under an ideal *** results show that the ratio of the upper mixed layer depth to Ekman depth scale(RME)RME=0.266(LAT=50°N)is a key value(latitude)for the modulation effect of the Coriolis parameter on the mean and turbulent statistics of Langmuir *** is found that the rate of change of the sea surface temperature,upper mixed layer depth,entrainment flux,crosswind velocity,downwind vertical momentum flux,and turbulent kinetic energy budget terms associated with Langmuir turbulence are more evident at RME≤0.266(LAT≤50°N)than at RME≥0.266(LAT≥50°N).However,the rate of change of the depth-averaged crosswind vertical momentum flux does not have a clear variation between RME≤0.266 and RME≥*** complex changes of both Langmuir turbulence characteristics and influence of Langmuir turbulence on the upper mixed layer with latitude presented here may provide more information for further improving Langmuir turbulence parameterization.

关键词： Langmuir turbulence Coriolis parameter the upper mixed layer large eddy simulation

Field-observation for an anticyclonic mesoscale eddy consisted of twelve gliders and sixty-two expendable probes in the northern South China Sea during summer 2017

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Science China Earth Sciences 2019年第2期62卷 451-458页

作者： yeqiang shu Ju CHEN shuo LI Qiang WANG Jiancheng YU Dongxiao WANG State Key Laboratory of Tropical Oceanography South China Sea Institute of Oceanology Chinese Academy of Sciences State Key Laboratory of Robotics Shenyang Institute of Automation Chinese Academy of Sciences

An intensive field observation experiment using 12 Chinese gliders equipped with conductivity-temperature-depth (CTD) sensors and 62 expendable CTD probes (XCTDs) was performed to investigate the 3-D structure and time evolution of an anticyclonic eddy in the northern South China Sea (NSCS). The observed results showed that the anticyclonic eddy had a horizontal radius of about 80 km at surface and a vertical depth of impact of more than 1000 m. The largest temperature and salinity anomalies compared with the averaged values of the temperature and salinity profiles were 3.5°C and 0.4 psu at 120 m depth, respectively. Combined analysis of altimeter sea level and water mass properties indicated that the anticyclonic eddy was shed from the Kuroshio loop current. The vertical axis of the anticyclonic eddy tilted from surface to the observed maximum depth (1000 m) along its translation direction against the 2000 m isobath. The center of the anticyclonic eddy remained in the region east of Dongsha Island for more than half a month. During this time, the long axis direction of the eddy changed from across the slope to along the slope. Then, the eddy moved southward along the 2000 m isobaths. Both the geostrophic current and temperature distribution revealed that the eddy intensity weakened during the observation period gradually. These observations indicated strong interaction between the anticyclonic eddy and the slope topography of Dongsha Island.

关键词： Anticyclonic mesoscale eddy Glider northern South China Sea

Progress on deep circulation and meridional overturning circulation in the South China Sea

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Science China Earth Sciences 2016年第9期59卷 1827-1833页

作者： WANG DongXiao XIAO JinGen shu yeqiang XIE Qiang CHEN Ju WANG Qiang State Key Laboratory of Tropical Oceanography South China Sea Institute of Oceanology Chinese Academy of Sciences College of Earth Sciences University of Chinese Academy of Sciences Institute of Deep Sea Science and Engineering Chinese Academy of Sciences

The deep overflow through the Luzon Strait drives the cyclonic deep circulation in the South China Sea(SCS). In the mean time, the intruding Pacific deep water transforms and upwells due to enhanced diapycnal mixing in the SCS. Both processes greatly contribute to the SCS meridional overturning circulation(SCSMOC). At the same time, both the deep circulation and meridional overturning circulation are modulated by rough topography in the SCS. Furthermore, the spatial structure of the SCSMOC infers a link between the upper-layer circulation and deep circulation in the SCS. This paper reviews recent advances in the SCS deep circulation and meridional overturning circulation, including the driving mechanism of the SCS deep circulation and its modulation by topography, as well as the spatial structure of the SCSMOC and its dynamical mechanism.

关键词： Luzon overflow SCS deep circulation SCSMOC Topography

The impact of ocean data assimilation on seasonal predictions based on the National Climate Center climate system model

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Acta Oceanologica Sinica 2021年第5期40卷 58-70页

作者： Wei Zhou Jinghui Li Fanghua Xu yeqiang shu Yang Feng Equipment Public Service Center South China Sea Institute of OceanologyChinese Academy of SciencesGuangzhou 510301China Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou) Guangzhou 511458China Ministry of Education Key Laboratory for Earth System Modeling Department of Earth System ScienceTsinghua UniversityBeijing 100084China State Key Laboratory of Tropical Oceanography South China Sea Institute of OceanologyChinese Academy of SciencesGuangzhou 510301China

An ensemble optimal interpolation(EnOI)data assimilation method is applied in the BCCCSM1.1 to investigate the impact of ocean data assimilations on seasonal forecasts in an idealized twin experiment *** of sea surface temperature(SST),sea surface height(SSH),sea surface salinity(SSS),temperature and salinity(T/S)profiles were first generated in a free model ***,a series of sensitivity tests initialized with predefined bias were conducted for a one-year period;this involved a free run(CTR)and seven assimilation *** tests allowed us to check the analysis field accuracy against the"truth".As expected,data assimilation improved all investigated quantities;the joint assimilation of all variables gave more improved results than assimilating them ***-year predictions initialized from the seven runs and CTR were then conducted and *** forecasts initialized from joint assimilation of surface data produced comparable SST root mean square errors to that from assimilation of T/S profiles,but the assimilation of T/S profiles is crucial to reduce subsurface *** ocean surface currents in the tropics were better predicted when initial conditions produced by assimilating T/S profiles,while surface data assimilation became more important at higher latitudes,particularly near the western boundary *** predictions of ocean heat content and mixed layer depth are significantly improved initialized from the joint assimilation of all the ***,a central Pacific El Ni?o was well predicted from the joint assimilation of surface data,indicating the importance of joint assimilation of SST,SSH,and SSS for ENSO predictions.

关键词： global ocean data assimilation EnOI twin experiments

Frontogenesis and Frontolysis of a Cold Filament Driven by the Cross-Filament Wind and Wave Fields Simulated by a Large Eddy Simulation

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Advances in Atmospheric Sciences 2024年第3期41卷 509-528页

作者： Guojing LI Dongxiao WANG Changming DONG Jiayi PAN yeqiang shu Zhenqiu ZHANG State Key Laboratory of Tropical Oceanography South China Sea Institute of OceanologyChinese Academy of SciencesGuangzhou 510301China Shool of Marine Sciences Nanjing University of Information Science and TechnologyNanjing 210044China School of Geography and Environment Jiangxi Normal UniversityNanchang 330022China Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai) Zhuhai 519080China

The variations of the frontogenetic trend of a cold filament induced by the cross-filament wind and wave fields are studied by a non-hydrostatic large eddy simulation. Five cases with different strengths of wind and wave fields are *** results show that the intense wind and wave fields further break the symmetries of submesoscale flow fields and suppress the levels of filament frontogenesis. The changes of secondary circulation directions—that is, the conversion between the convergence and divergence of the surface cross-filament currents with the downwelling and upwelling jets in the filament center—are associated with the inertial oscillation. The filament frontogenesis and frontolysis caused by the changes of secondary circulation directions may periodically sharpen and smooth the gradient of submesoscale flow *** lifecycle of the cold filament may include multiple stages of filament frontogenesis and frontolysis.

关键词： cold filament frontogenesis frontolysis large eddy simulation

Variation in concentration of dissolved silicate in the Eastern Philippine deep sea

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Journal of Oceanology and Limnology 2023年第4期41卷 1454-1463页

作者： Ruixue XIA Qiang XIE Weiqiang WANG Hongzhou XU Xuekun SHANG yeqiang shu Institute of Deep-Sea Science and Engineering Chinese Academy of SciencesSanya 572000China State Key Laboratory of Tropical Oceanography South China Sea Institute of OceanologyChinese Academy of SciencesGuangzhou 510301China Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou) Guangzhou 511458China Laboratory for Regional Oceanography and Numerical Modeling Pilot National Laboratory for Marine Science and Technology(Qingdao)Qingdao 266237China Center for Ocean Mega-Science Chinese Academy of SciencesQingdao 266071China University of Chinese Academy of Sciences Beijing 100049China School of Marine Sciences Sun Yat-sen UniversityGuangzhou 510275China

Upper Circumpolar Deep Water(UCDW)and North Pacifi c Deep Water(NPDW)coexist in the upper deep layer(i.e.,with a 1.2-2.0-℃potential temperature range and a 2000-4100-dbar pressure range)of the Eastern Philippine *** have similar properties in potential temperature and salinity,while have a signifi cant diff erence in dissolved *** on the repeated observations along a 137°E transect from the World Ocean Database(WOD18),this study revealed the interannual variability of dissolved silicate in the upper deep layer of the Eastern Philippine *** silicate increased in 1995,1996,2005,2006,and 2007,and decreased in 1997,2000,2001,2002,and *** analysis showed that the large diff erence between positive and negative dissolved silicate anomalies occurred mainly at~15°N and north of 25°N,with the concentration reaching 4.25μmol/*** analysis indicated that the interannual dissolved silicate variability was related to the zonal current variation in the upper deep *** relatively strong(weak)westward current transport increased(decreased)NPDW to the Eastern Philippine Sea,thereby resulting in increased(decreased)dissolved silicate.

关键词： interannual variability North Pacific deep water upper deep layer dissolved silicate zonal velocity variability

Origin of the springtime South China Sea Warm Current in the southwestern Taiwan Strait: Evidence from seawater oxygen isotope

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Science China Earth Sciences 2020年第10期63卷 1564-1576页

作者： Dongyu CHEN Ergang LIAN yeqiang shu Shouye YANG Yalong LI Chao LI Pengfei LIU Ni SU State Key Laboratory of Marine Geology Tongji UniversityShanghai 200092China State Key Laboratory of Tropical Oceanography South China Sea Institute of OceanologyChinese Academy of SciencesGuangzhou 510301China

Oxygen isotope(δ^18O)of seawater is an excellent proxy for tracing the origins of water masses and their mixing *** with hydrographic observation,hybrid coordinate ocean model(HYCOM)analysis data,and seawater oxygen isotope,we investigated the source of the South China Sea Warm Current(SCSWC)in the southwestern Taiwan Strait and its underlying *** show that the Kuroshio subsurface water(KSSW)can intrude the continental slope in the southwestern Taiwan Strait,and thereby climb up the continental slope coupled with ***δ^18O-salinity relationship further indicates that in spring,the SCSWC in the southwestern Taiwan Strait originates from the upslope deflection of the slope current formed by the KSSW intrusion into the South China Sea,rather than from the west segment of the SCSWC formed to the east of Hainan *** addition,the southward flowing Zhe-Min Coastal Current(ZMCC)can reach as far as the Taiwan Bank(TB)and deflects offshore over the western TB at approximately 23.5°N,to some extent affecting the ***,this study reveals that seawaterδ^18O is exquisitely sensitive to the determination of the origin and transport of water masses as compared with traditional potential temperature-salinity plot(θ-S)and HYCOM analysis *** addition,their coupling can more reliably interpret the mixing processes of shelf water masses.

关键词： Oxygen isotope South China Sea Warm Current Zhe-Min Coastal Current Kuroshio Southwestern Taiwan Strait

Assimilating temperature and salinity profiles using Ensemble Kalman Filter with an adaptive observation error and T-S constraint

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Acta Oceanologica Sinica 2016年第1期35卷 30-37页

作者： LIU Danian SHI Ping shu yeqiang YAO Jinglong WANG Dongxiao SUN Lu State Key Laboratory of Tropical Oceanography South China Sea Institute of Oceanology Chinese Academy of Sciences Guangzhou 510301 China South China Sea Monitoring Center South China Sea Branch State Oceanic Administration Guangzhou 510301 China

Temperature （T） and salinity （S） profiles from conductivity-temperature-depth data collected during the Northern South China Sea Open Cruise from August 16 to September 13, 2008 are assimilated using Ensemble Kalman Filter （EnKF）. An adaptive observational error strategy is used to prevent filter from diverging. In the meantime, aiming at the limited improvement in some sites caused by the T and S biases in the model, a T-S constraint scheme is adopted to improve the assimilation performance, where T and S are separately updated at these locations. Validation is performed by comparing assimilated outputs with independent in situ data （satellite remote sensing sea level anomaly （SLA）, the OSCAR velocity product and shipboard ADCP）. The results show that the new EnKF assimilation scheme can significantly reduce the root mean square error （RMSE） of oceanic T and S compared with the control run and traditional EnKF. The system can also improve the simulation of circulations and SLA.

关键词： Ensemble Kalman Filter adaptive observation error T-S constraint

Contrasting dynamic characteristics of shear turbulence and Langmuir circulation in the surface mixed layer

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Acta Oceanologica Sinica 2015年第5期34卷 1-11页

作者： LI Guojing WANG Dongxiao CHEN Ju YAO Jinglong ZENG Lili shu yeqiang SUI Dandan State Key Laboratory of Tropical Oceanography South China Sea Institute of OceanologyChinese Academy of Sciences

Large eddy simulation （LES） is used to investigate contrasting dynamic characteristics of shear turbulence （ST） and Langmuir circulation （LC） in the surface mixed layer （SML）. ST is usually induced by wind forcing in SML. LC can be driven by wave-current interaction that includes the roles of wind, wave and vortex forcing. The LES results show that LC suppresses the horizontal velocity and greatly modifies the downwind velocity profile, but increases the vertical velocity. The strong downweUing jets of LC accelerate and increase the downward transport of energy as compared to ST. The vertical eddy viscosity Km of LC is much larger than that of ST. Strong mixing induced by LC has two locations. They are located in the 26s-36s （Stokes depth scale） and the lower layer of the SML, respectively. Its value and position change periodically with time. In contrast, maximum Km induced by ST is located in the middle depth of the SML. The turbulent kinetic energy （TKE） generated by LC is larger than that by ST. The differences in vertical distributions of TKE and Krn are evident. Therefore, the parameterization of LC cannot be solely based on TKE. For deep SML, the convection of large-scale eddies in LC plays a main role in downward transport of energy and LC can induce stronger velocity shear （S2） near the SML base. In addition, the large-scale eddies and Sz induced by LC is changing all the time, which needs to be fully considered in the parameterization of LC.

关键词： surface mixed layer Langmuir circulation shear turbulence large eddy simulation