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| 1 | Application of altimetry data assimilation on mesoscale eddies simulation显示文摘Mesoscale eddy plays an important role in the ocean circulation. In order to improve the simulation accuracy of the mesoscale eddies, a three-dimensional variation (3DVAR) data assimilation system called Ocean Variational Analysis System (OVALS) is coupled with a POM model to simulate the mesoscale eddies in the Northwest Pacific Ocean. In this system, the sea surface height anomaly (SSHA) data by satellite altimeters are assimilated and translated into pseudo temperature and salinity (T-S) profile data. Then, these profile data are taken as observation data to be assimilated again and produce the three-dimensional analysis T-S field. According to the characteristics of mesoscale eddy, the most appropriate assimilation parameters are set up and testified in this system. A ten years mesoscale eddies simulation and comparison experiment is made, which includes two schemes: assimilation and non-assimilation. The results of comparison between two schemes and the observation show that the simulation accuracy of the assimilation scheme is much better than that of non-assimilation, which verified that the altimetry data assimilation method can improve the simulation accuracy of the mesoscale dramatically and indicates that it is possible to use this system on the forecast of mesoscale eddies in the future. | GAO Shan WANG Fan LI MingKui CHEN YongLi YAN ChangXiang ZHU Jiang | 2008 | Science China Earth Sciences2008,51,1: | 10 |
| 2 | PROPAGATION OF LONG-LIVED ANTICYCLONIC ROSSBY EDDIES OVER AN ISOLATED TOPOGRAPHY AND THEIR MERGING显示文摘In this paper, in a barotropic model the propagation of long lived anticylonic Gaussian eddies larger than the radius of deformation over a Gaussian shaped topography and the merging of the two anticyclonic eddies are investigated by solving the generalized Flierl Yamagata equation. It is shown that whether or not the basic flow is present, the isoated topography seems to encourage the amplification of an anticyclonic eddy and its southwest movement around the hill. In the absence of both the westward flow and the topography, two anticyclonic eddies of indentical sizes and amplitudes can merge. However, either the including of the topography or the westward basic flow can make them not merge. In the presence of both, the eddies can merge, but this merging depends on whether the parameter condition is appropriate or not. Therefore, it can be concluded that the topographic forcing might be a possible mechanism for the merging of two anticyclonic eddies. | Luo, De-Hai Lu, Yan | 2001 | Journal of Hydrodynamics2001,13,3: | 2 |
| 3 | Response of the Kuroshio Current to Eddies in the Luzon Strait显示文摘The impact of eddies on the Kuroshio Current in the Luzon Strait (LS) area is investigated by using the sea surface height anomaly (SSHA) satellite observation data and the sea surface height (SSH) assimilation data. The influence of the eddies on the mean current depends upon the type of eddies and their relative position. The mean current is enhanced (weakened) as the cyclonic (anticyclonic) eddy becomes slightly far from it, whereas it is weakened (enhanced) as the cyclonic (anticyclonic) eddy moves near or within the position of the mean current; this is explained as the eddy-induced meridional velocity and geostrophic flow relationship. The anticyclonic (cyclonic) eddy can increase (decrease) the mean meridional flow due to superimposition of the eddy-induced meridional flow when the eddy is within the region of the mean current. However, when the eddy is slightly far from the mean current region, the anticyclonic (cyclonic) eddy tends to decrease (increase) the zonal gradient of the SSH, which thus results in weakening (strengthening) of the mean current in the LS region. | Zhao Jie Luo De-Hai | 2010 | Atmospheric and Oceanic Science Letters2010,3,3: | 2 |
| 4 | Characteristics and temporal variations of near-bottom currents near the Dongsha Island in the northern South China Sea显示文摘Near-bottom currents play important roles in the formation and dynamics of deep-water sedimentary systems.This study examined the characteristics and temporal variations of near-bottom currents, especially the tidal components, based on two campaigns(2014 and 2016) of in situ observations conducted southeast of the Dongsha Island in the South China Sea. Results demonstrated near-bottom currents are dominated by tidal currents, the variance of which could account for ~70% of the total current variance. Diurnal tidal currents were found stronger than semidiurnal currents for both barotropic and baroclinic components. The diurnal tidal currents were found polarized with predominantly clockwise-rotating constituents, whereas the clockwise and counterclockwise constituents were found comparable for semidiurnal tidal currents. It was established that diurnal tidal currents could induce strong current shear. Baroclinic tidal currents showed pronounced seasonal variation with large magnitude in winter and summer and weak magnitude in spring and autumn in 2014. The coherent components accounted for ~65% and ~50% of the diurnal and semidiurnal tidal current variances,respectively. The proportions of the coherent and incoherent components changed little in different seasons. In addition to tidal currents, it was determined that the passing of mesoscale eddies could induce strong nearbottom currents that have considerable influence on the deep circulation. | Dawei Li Zexun Wei Yonggang Wang Shujiang Li Tengfei Xu Guanlin Wang Fei Teng | 2019 | Acta Oceanologica Sinica2019,38,4: | 1 |
| 5 | Influence of warm eddies on sound propagation in the Gulf of Mexico显示文摘An automatic detection method is employed to identify and track eddies in the Gulf of Mexico. The physical parameters of the eddies, such as lifespan, radius, and distribution position are first examined and used to determine the spatio–temporal evolution of a strong warm eddy separated from the Mexico current. Then, the influence of this strong warm eddy on sound propagation during its lifespan are comprehensively analyzed with the parabolic equation and explained by using the normal mode and ray theories. Additionally, the influence of mesoscale eddies on the redistribution of total depth-integrated energy among the normal modes in the deep water is also discussed. The variation of arrival angle is investigated to explain the spreading acoustic energy caused by eddies. Overall, the results show that warm eddies can change the propagation paths and cause the convergence zone to broaden and approach the sound source. Moreover,the warm eddy can disperse sound energy and cause the total depth-integrated energy to incline to a lower normal mode.Throughout the whole of these three periods(eddy generating, eddy maturing, and eddy terminating), the fluctuation in the transmission loss is up to 30 dB(depending on the relative location of eddy center to the source). | 肖瑶 李整林 李鋆 刘佳琪 Karim G Sabra | 2019 | Chinese Physics B2019,28,5: | 1 |
| 6 | Impacts of model resolution on simulation of mesoscale eddies in the Northeast Pacific Ocean显示文摘The model simulated meso-scale eddies in the Northeast Pacific Ocean, using two models with nominal horizontal resolutions of 1/12° and 1/36° in latitude/longitude (grid spacing of 7.5 km and 2.5 km), respectively, are presented. Compared with the 1/12° model, the 1/36° model obtains (1) similar variance and wave number spectra of the sea level anomaly and water temperature anomaly, and (2) increases in the level of the domain-averaged total kinetic energy, eddy kinetic energy (EKE), and variance of horizontal gradient of water temperature. In the interior basin of the southern region, both models show stronger eddy frontal activities, represented by EKE, temperature and its horizontal gradient, in summer and fall than in winter and spring. The challenge of evaluating the realism of highresolution ocean models with conventional satellite remote sensing observations is discussed. | Youyu Lu Jiaxing Li Ji Lei Charles Hannah | 2017 | Satellite Oceanography and Meteorology2017,2,2: | 0 |
| 7 | The energy conversion rates from eddies and mean fl ow into internal lee waves in the global ocean显示文摘Internal lee waves play an important role in transferring energy from eddies to small scale mixing.However,the energy conversion from eddies into lee waves in the global ocean remains poorly understood.Conversion rates from eddies and from mean fl ow in the global ocean were diff erentiated using single beam sounding data,stratifi cation from climatology,eddy velocity,and mean fl ow from a global ocean model.The global integral energy conversion from eddies is estimated to be 0.083 TW and is almost twice as that from the mean fl ow.A new method was developed to study the uncertainties of energy conversion caused by dealing with the topographic data.Results show that diff erent data processing procedures,and the resolution and accuracy of topographic data have a signifi cant impact on the estimated global energy conversion. | Bing HAN | 2022 | Journal of Oceanology and Limnology2022,40,4: | 0 |
| 8 | Net-phytoplankton communities in the Western Boundary Currents and their environmental correlations显示文摘This study investigated net-phytoplankton biomass, species composition, the phytoplankton abundance horizontal distribution, and the correlations between net-phytoplankton communities and mesoscale structure that were derived from the net samples taken from the Western Boundary Currents during summer, 2014. A total of 199 phytoplankton species belonging to 61 genera in four phyla were identified. The dominant species included C limacodium frauenfeldianum, Thalassiothrix longissima, Rhizosolenia styliformis var. styliformis, Pyrocystis noctiluca, Ceratium trichoceros, and Trichodesmium thiebautii. Four phytoplankton communities were divided by cluster analysis and the clusters were mainly associated with the North Equatorial Counter Current(NECC), the North Equatorial Current(NEC), the Subtropical Counter Current(STCC), and the Luzon Current(LC), respectively. The lowest phytoplankton cell abundance and the highest T richodesmium filament abundance were recorded in the STCC region. The principal component analysis showed that T. thiebautii preferred warm and nutrient poor water. There was also an increase in phytoplankton abundance and biomass near 5°N in the NECC region, where they benefit from upwellings and eddies. | 陈芸燕 孙晓霞 朱明亮 | 2018 | Journal of Oceanology and Limnology2018,36,2: | 0 |
| 9 | A NOTE ON A NEW THEORY OF TURBULENCE显示文摘In this paper,the creation and annihilaton of turbulent eddies are described aselementary particles in the quantum field theory.An elementary particle may be consideredas a solid entity as it exists in quantum theory,but a turbulent eddy is often changed in sizeand shape with time due to its energy dissipation in a turbulent field.Therefore,in order toapply the method of the quantum field theory to the turbulent field by analogy,the entity ofthe same eddy should be defined firstly.According to the linearized theory,the turbulenteddies with the similarity character in lime duration may be considered as the entity of thesame eddy,and the creation and annihilation of turbulent eddies without the similarcharacters are related to the interaction term φ2 in equation(2.6).Then,the creationoperator and annihilation operator similar to those in the quantum field theory are used todescribe the state of turbulent eddy field.Finally,a“Schrǒdinger”equation of turbulenteddies is formulated based upon the | 蔡树棠 林多敏 | 1991 | Applied Mathematics and Mechanics(English Edition)1991,12,1: | 0 |