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Spatiotemporal features and vertical structures of four types of mesoscale eddies in the Kuroshio Extension region

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Acta Oceanologica Sinica 2024年第5期43卷 30-40页

作者： Bowen Sun Shuchang Xu Zhankun Wang Yujie Feng Baofu Li School of Geography and Tourism Qufu Normal UniversityRizhao 276800China Faculty of Information Science and Engineering Ocean University of ChinaQingdao 266100China

Except for conventional mesoscale eddies,there are also abundant warm cyclonic eddies(WCEs)and cold anticyclonic eddies(CAEs)in the global ocean.Based on the global mesoscale eddy trajectory atlas product,satellite altimetric and remote sensing datasets,and three-dimensional temperature/salinity dataset,spatiotemporal features of WCEs and CAEs are compared with traditional cold cyclonic eddies and warm anticyclonic eddies in the Kuroshio Extension(KE;28°−43°N,140°−170°E)region.Characteristics of abnormal eddies like radius,amplitude,eddy kinetic energy,and proportion in all eddies behave in significant asymmetry on the north and south sides of the KE jet.Unlike eddies in the general sense,temporal feature analysis reveals that it is more favorable to the formation and maintenance of WCEs and CAEs in summer and autumn,while winter is the opposite.The spatiotemporal variation of abnormal eddies is likely because the marine environment varying with time and space.Statistically,proportion of abnormal eddies increases rapidly in decaying stage during the whole eddy lifespan,resulting in smaller average radius,amplitude,sea surface temperature anomaly and sea surface height anomaly compared to normal ones.The three-dimensional composite structures for four types of eddies expose that the difference between abnormal and conventional eddies is not just limited to the sea surface,but also exists within the water below the sea surface.Vertical structures also indicate that the anomalous temperature signal is confined in the water from the sea surface to layers at about 30 m in the KE region.

关键词： mesoscale anomaly Kuroshio

An efficient approach for mesoscale fracture modeling of fully-graded hydraulic concrete

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Water Science and Engineering 2022年第4期15卷 337-347页

作者： Lei Xu Lei Jiang Ye-fei Huang Qing-wen Ren College of Water Conservancy and Hydropower Engineering Hohai UniversityNanjing 210098China

Large coarse aggregates used in fully-graded hydraulic concrete necessitate large specimens for numerical modeling.This leads to a high computational cost for mesoscale modeling and thus slows the development of multiscale modeling of hydraulic mass concrete structures.To overcome this obstacle,an efficient approach for mesoscale fracture modeling of fully-graded hydraulic concrete was developed based on the concept of the governing mesostructure.The mesostructure was characterized by a critical aggregate size.Coarse aggregates smaller than the critical size were homogenized into mortar matrices.Key issues in mesostructure generation of fully-graded hydraulic concrete are discussed,as is the development of mesoscale finite element modeling methodology.The basic concept and implementation procedures of the proposed approach are also described in detail.The numerical results indicated that the proposed approach not only significantly improves the compu-tational efficiency of mesoscale modeling but also captures the dominant fracturing mechanism at the mesoscale and reproduces reasonable fracture properties at the macroscale.Therefore,the proposed approach can serve as a basis for multiscale fracture modeling of hydraulic mass concrete structures.

关键词： Fully-graded hydraulic concrete mesoscale Fracture modeling Governing mesostructure Critical aggregate size

mesoscale SST perturbation-induced impacts on climatological precipitation in the Kuroshio-Oyashio extension region,as revealed by the WRF simulations

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Journal of Oceanology and Limnology 2019年第2期37卷 385-397页

作者： GAO Jiaxiang ZHANG Rong-Hua WANG Hongna CAS Key Laboratory of Ocean Circulation and Waves Institute of Oceanology Chinese Academy of Sciences Qingdao 266071China University of Chinese Academy of Sciences Beijing 100049 China Laboratory for Ocean Dynamics and Climate Qingdao National Laboratory for Marine Science and Technology Qingdao 266237 China

mesoscale coupling between perturbations of mesoscale sea surface temperature (SST) and lowlevel winds has been extensively studied using available high-resolution satellite observations. However, the climatological impacts of mesoscale SST perturbations (SST meso ) on the free atmosphere have not been fully understood. In this study, the rectified eff ect of SSTmeso on local climatological precipitation in the Kuroshio- Oyashio Extension (KOE) region is investigated using the Weather Research and Forecasting (WRF) Model;two runs are performed, one forced by low-resolution SST fields (almost no mesoscale signals) and another by additional high-resolution SSTmeso fields extracted from satellite observations. Climatological precipitation response to SST meso is characterized mainly by enhanced precipitation on the warmer flank of three oceanic SST fronts in this region. The results show that the positive correlation between the 10-m wind speed perturbations and SSTmeso is well captured by the WRF model with a reasonable spatial pattern but relatively weak strength. The addition of SSTmeso improves the climatological precipitation simulated by WRF with a better representation of fine-scale structures compared with satellite observations. A closer examination on the underlying mechanism suggests that while the pressure adjustment mechanism can explain the climatological precipitation enhancement along the fronts and the relatively high contribution of the convective precipitation, other factors such as synoptic events should also be taken into consideration to account for the seasonality of the precipitation response.

关键词： mesoscale SST perturbations and eff ects WRF model Kuroshio-Oyashio Extension climatological precipitation

mesoscale Predictability of Moist Baroclinic Waves: Variable and Scale-dependent Error Growth

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Advances in Atmospheric Sciences 2014年第5期31卷 995-1008页

作者： BEI Naifang Fuqing ZHANG School of Human Settlements and Civil Engineering Xi'an Jiaotong University Department of Meteorology the Pennsylvanian State University University ParkPennsylvania 16802 USA

This study seeks to quantify the predictability of different forecast variables at various scales through spectral analysis of the difference between perturbed and unperturbed cloud-permitting simulations of idealized moist baroclinic waves amplify- ing in a conditionally unstable atmosphere. The error growth of a forecast variable is found to be strongly associated with its reference-state （unperturbed） power spectrum and slope, which differ significantly from variable to variable. The shallower the reference state spectrum, the more spectral energy resides at smaller scales, and thus the less predictable the variable since the error grows faster at smaller scales before it saturates. In general, the variables with more small-scale components （such as vertical velocity） are less predictable, and vice versa （such as pressure）. In higher-resolution simulations in which more rigorous small-scale instabilities become better resolved, the error grows faster at smaller scales and spreads to larger scales more quickly before the error saturates at those small scales during the first few hours of the forecast. Based on the reference power spectrum, an index on the degree of lack （or loss） of predictability （LPI） is further defined to quantify the predictive time scale of each forecast variable. Future studies are needed to investigate the scale- and variable-dependent predictability under different background reference flows, including real case studies through ensemble experiments.

关键词： predictability baroclinic waves error growth mesoscale

mesoscale Moist Adjoint Sensitivity Study of a Mei-yu Heavy Rainfall Event

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Advances in Atmospheric Sciences 2010年第6期27卷 1415-1424页

作者：储可宽谈哲敏 Key Lab of mesoscale Severe Weather/MOE and School of Atmospheric SciencesNanjing University

The mesoscale moist adjoint sensitivities related to the initiation of mesoscale convective systems （MCSs） are evaluated for a mei-yu heavy rainfall event. The sensitivities were calculated on a realistic background gained from a four-dimensional variational data assimilation of precipitation experiment to make the sensitivity computation possible and reasonable within a strong moist convective event at the mesoscale. The results show that the computed sensitivities at the mesoscale were capable of capturing the factors affecting MCS initiation. The sensitivities to the initial temperature and moisture are enhanced greatly by diabatic processes, especially at lower levels, and these sensitivities are much larger than those stemming from the horizontal winds, which implies that initiation of MCSs is more sensitive to low-level temperature and moisture perturbations rather than the horizontal winds. Moreover, concentration of sensitivities at low levels reflects the characteristics of the mei-yu front. The results provide some hints about how to improve quantitative precipitation forecasts of mei-yu heavy rainfall, such as by conducting mesoscale targetted observations via the adjoint-based method to reduce the low-level errors in the initial temperature and moisture.

关键词： adjoint sensitivity analysis mei-yu heavy rainfall mesoscale

mesoscale Characteristics Analysis of a Fog Case with Complete Weather Information Derived from FengYun-4A Data

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Meteorological and Environmental Research 2022年第2期13卷 10-27页

作者： Wei WANG Ping QU Zhijie LIU Tianjin Key Laboratory for Oceanic Meteorology Tianjin 30074China Tianjin Institute of Meteorological Sciences Tianjin 300074China Meteorology Administration of Xiqing District Tianjin 300380China

Currently,there is a lack of sufficient ocean meteorological data required for mesoscale weather predictions and fog characteristics analysis in the North China Sea.This study presents a methodology to supplement deficiencies in wind information in retrieval data from the Geostationary Interferometric Infrared Sounder(GIIRS)onboard the FengYun-4A(FY4A)satellite and analyze mesoscale weather characteristics.Atmospheric semi-geostrophic wind data were derived from semi-geostrophic theory to complete the weather elements in FY4AGIIRS retrieval data.First,the retrieval data accuracy was analyzed between L-band radiosonde data from seven stations and retrieval data from FY4AGIIRS.The errors in the temperature,humidity,and geopotential height from 850 to 400 hPa were smaller than those of other atmospheric layers.Subsequently,the mesoscale weather characteristics of a fog event were analyzed by creating a mesoscale weather map with derived weather information between 875 and 500 hPa.The analyses showed that the derived weather information might provide a new means for fog mesoscale characteristics analysis,which can help forecasters understand the spatial inhomogeneity in the visibility of fog events.

关键词： Satellite Fog mesoscale Semi-geostrophic wind Weather map

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

Game-theoretical explorations of the mesoscale flow structure and regime transitions in bubble columns

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Particuology 2020年第1期18卷 100-108页

作者： Shuo Yuan Yifen Mu Xiaoping Guan Zhixin Liu Jianhua Chen Ning Yang Lin Zhang Key Lab of Systems and Control Institute of Systems SciencesAcademy of Mathematics and Systems ScienceChinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China State Key Laboratory of Multiphase Complex Systems Institute of Process EngineeringChinese Academy of SciencesBeijing 100190China

Understanding the mesoscale structure and regime transition in bubble columns is of great significance for reactor design and scaleup.Based on the energy-minimization multiscale(EMMS)model,a noncooperative game model with constraints is proposed to investigate the structural properties of gas-liquid systems in which small and large bubbles are chosen as players and the energy consumption form the objective function.The conservation equations of the system can be regarded as the constraints of the game.For the formulated noncooperative game model,the concept of the generalized Nash equilibrium(GNE)is used to characterize the solution.An algorithm is developed to numerically compute the GNE and some important structural parameters in the system.The numerical results show the existence of the GNE for all values of the superficial gas velocity Ug.As Ug varies,the trends in the state variables can be observed and the critical point of Ug identified.The overall trend of the flow regime transition agrees with the original EMMS model and experimental results,although the GNE calculation also reveals different single-bubble dominant mechanisms with increasing Ug.

关键词： Bubble column mesoscale Regime transition Game theory Generalized Nash equilibrium EMMS model

Role of ultrasonic oscillation in chemical processes in microreactors:A mesoscale issue

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Particuology 2020年第1期18卷 88-99页

作者： Shuainan Zhao Chaoqun Yao Zhengya Dong Guangwen Chen Quan Yuan Dalian National Laboratory for Clean Energy Dalian Institute of Chemical PhysicsChinese Academy of SciencesDalian 116023China University of Chinese Academy of Sciences Beijing 100049China

The integration of microreactor and ultrasound represents an emerging area for process intensification and has attracted considerable attention in recent years.One of the most important meso-scientific issues in ultrasound techniques is acoustic cavitation,which plays a vital role in the macroscopic performance of an ultrasonic microreactor.In this review,we first briefly summarize the latest research on acoustic cavitation phenomena in microreactors.The effects of channel configuration,solvent properties,and ultrasound parameters are systematically reviewed.In addition,the role of acoustic cavitation in various chemical processes(e.g.,mixing,absorption,emulsification,and particle synthesis)is presented from a mesoscale perspective,which in turn provides guidance for ultrasound applications.A thorough under-standing of the ultrasound intensification mechanism will contribute to the future development of this promising technology.

关键词： Ultrasound Microreactor Acoustic cavitation mesoscale Process intensification