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Effect of opening the Drake Passage on the oceanic general circulation:A box model study

Science China Earth Sciences 2013年第2期56卷 1588-1598页

作者： SHAO QiuLi CHEN XianYao HUANG RuiXin Key Laboratory of Data Analysis and Applications State Oceanic Administration The First Institute of Oceanography State Oceanic Administration Woods Hole Oceanographic Institution

The impacts of opening the Drake Passage(DP) on the oceanic general circulation are *** the DP is open,wind stress at mid-and high latitudes gives rise to a wind-driven gyre,which induces a meridional heat exchange between mid-and high latitudes in the Southern *** the opening of the DP,the Antarctic Circumpolar Current(ACC) forms and its associated strong temperature front blocks the heat transport from mid-latitudes to high latitudes.A simple box model is formulated,in which the effects of the wind stress(for the case of DP closed) and the thermal front(for the case of DP open) on the variability of Antarctic Bottom Water(AABW) and North Atlantic Deep Water(NADW) are *** sensitivity experiments demonstrate that:(1) When the DP is closed,the enhancement of the wind-driven gyre leads to the decline of AABW formation in the Southern Ocean and the increase of NADW formation in the North *** a result,water in high latitudes of the Southern Ocean becomes warmer,so does the bottom water of global ocean.(2) When the DP is open,there is no formation of AABW until the intensity of thermal front along ACC exceeds a threshold value(it is 4.03℃ in our model).Before the formation of AABW,temperature in most of the oceans is higher than that after the formation of AABW,which usually leads to the cooling of high latitudes of the Southern Hemisphere and the bottom water in global *** the strength of the thermal front is lower than the critical value,there is no AABW formation,and temperature in most of the oceans is slightly *** results demonstrate that during the opening of the DP,changes in wind stress and the formation of the thermal front in the Southern Ocean can substantially affect the formation of AABW and NADW,thus changing the state of meridional overturning circulation in the global ocean.

关键词： Effect of opening the Drake Passage on the oceanic general circulation：A box model study

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Multifractal Detrended Fluctuation analysis of Interevent Time Series in a Modified OFC Model

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Communications in Theoretical Physics 2013年第1期59卷 1-6页

作者：林敏颜双喜赵钢王刚 Department of Mathematics Ocean University of China College of Civil Aviation Nanjing University of Aeronautics and Astronautics Faculty of Transportation Engineering of Huaiyin Institute of Technology Key Laboratory of Data Analysis and Applications(LDAA) First Institute of OceanographyState Oceanic Administration

We use multifractal detrended fluctuation analysis （MF-DFA） method to investigate the multifractal behavior of the interevent time series in a modified Olami-Feder-Christensen （OFC） earthquake model on assortative scale-free networks. We determine generalized Hurst exponent and singularity spectrum and find that these fluctuations have multifraetal nature. Comparing the MF-DFA results for the original interevent time series with those for shuffled and surrogate series, we conclude that the origin of multifractality is due to both the broadness of probability density function and long-range correlation.

关键词： multifractal detrended fluctuation analysis avalanche correlations

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Exploring the Ocean's Role in Climate Change

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Eos, Transactions American Geophysical Union 2013年第13期94卷 126-126页

作者： John M. Wallace Xianyao Chen Department of Atmospheric Sciences University of Washington Seattle Key Laboratory of Data Analysis and Applications First Institute of Oceanography Qingdao China

The instrumental record of global surface temperature since the 1850s shows multidecadal variability (MDV) superimposed on a secular global warming trend. The unprecedented rate of warming in the late 20th century coi... 详细信息

关键词： multidecadal climate variability interdecadal climate variability atmosphere-ocean interactions

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A review on the South China Sea western boundary current

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Acta Oceanologica Sinica 2012年第5期31卷 1-10页

作者： FANG Guohong WANG Gang FANG Yue FANG Wendong Key Laboratory of Marine Science and Numerical Modeling First Institute of OceanographyState Oceanic AdministrationQingdao 266061China Key Laboratory of Data Analysis and Applications First Institute of OceanographyState Oceanic AdministrationQingdao 266061China Center for Ocean and Climate Research First Institute of OceanographyState Oceanic AdministrationQingdao 266061China State Key Laboratory of Tropical Oceanography South China Sea Institute of OceanologyChinese Academy of SciencesGuangzhou 510301China

The advances in understanding the South China Sea （SCS） western boundary current （SCSwbc） have been reviewed since the works of Dale （1956） and Wyrtki （1961） in the middle of the 20th century. The features of the pattern of SCSwbc and the oceanic phenomena associated with it are focused on. The current is driven mainly by monsoon over the SCS and partially by winds over the tropical Pacific governed by the island rule. The SCSwbc exhibits strong seasonal variation in its direction and patterns. In winter, the current is strong and flows southwestward along the South China shelf and slope from the east of Dongsha Islands to the northern central Vietnamese coast, then turns to the south along the central and southern Vietnamese coast, and finally partially exits the SCS through the Karimata Strait. In summer and early fall, the SCSwbc can be divided into three segments based on their characteristics. The southern segment is stable, flowing northward from the Karimata Strait up to about 11 N, where it separates from the coast forming an eastward offshore current. The separation of the current from Vietnamese coast induces some striking features, such as upwelling and cold sea-surface temperature. The middle segment off the central Vietnamese coast may have a bimodal behavior： northward coastal current and meandering current in early summer （June–July）, and cyclonic gyre in later summer and early fall （August–September）. The northern segment is featured by the summer SCS Warm Current on the South China shelf and a southwestward subsurface current along the continental slope.

关键词： South China Sea western boundary current Vietnam offshore current upwelling subsurface current

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Measurement of the Irregular Geometric Shapes

Measurement of the Irregular Geometric Shapes

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2012 International Conference on Mechanical Engineering and Materials(ICMEM 2012)

作者： WANG Gang HUANG Norden E HSU Wei-Tai LO Men-Tzung QIAO Fangli LIN Min Research Center for Adaptive Data Analysis & Center for Dynamical Biomarkers and Translational Medicine “National Central University” Key Laboratory of Data Analysis and Applications First Institute of Oceanography SOA Department of Mathematics Ocean University of China

Image presents the basic physical features of an object. Geometry, on the other hand, provides us a powerful way to quantify the information reflected by images or their shapes. Traditional geometry however finds limitation in describing the differences between highly irregular objects,which requires us to find new approaches to measure an object and quantify its difference from another. In this paper, we define some scalars in two dimensions to meet this demand. These approaches, grounded on circularity, convexity and cavity, describe the geometry of shapes in statistic sense, and they can also be applied to qualify the differences of shapes.

关键词： image processing circularity convexity cavity

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A possible generation mechanism of the strong current over the northwestern shelf of the South China Sea

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Acta Oceanologica Sinica 2011年第3期30卷 27-32页

作者： WANG Gang QIAO Fangli DAI Dejun HOU Yijun Key laboratory of Data Analysis and Applications （LDAA） Key laboratory of Marine Science and Numerical Modeling （MASNUM） First Institute of Oceanography State Oceanic Administration Qingdao 266061 China Institute of Oceanology Chinese Academy of Sciences Qingdao 266071 China

Continuous observation in late April 2005 on the northwestern shelf of the South China Sea reveals vigorous strong currents, the maximum velocity of which exceeds 3.8 m/s. The strong currents occurred around spring tide period, when the internal tide waves were also expected to be vigorous. analysis shows that the major peaks of the current power spectrum are in low frequency band. Using a numerical method applied to the actual ocean stratification, we find that the amplitude profiles of the strong current are similar to that of the currents induced by some low-mode internal waves （at diurnal or semi-diurnal frequency）. It indicates that the temporal and spatial features of strong currents were possibly induced by low frequency internal waves.

关键词： strong current internal waves Brunt-Vaisala frequency

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OPTIMAL SELECTION FOR THE WEIGHTED COEFFICIENTS OF THE CONSTRAINED VARIATIONAL PROBLEMS

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Applied Mathematics and Mechanics(English Edition) 2003年第8期24卷 936-944页

作者：魏鸣刘国庆王成刚葛文忠许秦 Key Laboratory of Mesoscale Severe Weather Ministry of EducationNanjing University Nanjing 210093 P.R.China School of Science Nanjing University of TechnologyNanjing 210009 P. R. China National Severe Storms Laboratory NOAA 1313 Halley Circle Norman OK 73069 USAhe aim is to put forward the optimal selecting of weights in variational problemin which the linear advection equation is used as constraint. The selection of the functionalweight coefficients ( FWC) is one of the key problems for the relevant research. It wasarbitrary and subjective to some extent presently. To overcome this difficulty thereasonable assumptions were given for the observation field and analyzed field variationalproblems with " weak constraints" and " strong constraints" were considered separately. Bysolving Euler' s equation with the matrix theory and the finite difference method of partialdifferential equation the objective weight coefficients were obtained in the minimumvariance of the difference between the analyzed field and ideal field. Deduction results showthat theoretically the optimal selection indeed exists in the weighting factors of the costfunction in the means of the minimal variance between the analysis and ideal field in terms ofthe matrix theory and partial differential ( corresponding difference ) equation if thereasonable assumption from the actual problem is valid and the differnece equation is stable.It may realize the coordination among the weight factors numerical models and theobservational data. With its theoretical basis as well as its prospects of applications thisobjective selecting method is probably a way towards the finding of the optimal weightingfactors in the variational problem.

The aim is to put forward the optimal selecting of weights in variational problemin which the linear advection equation is used as constraint. The selection of the functionalweight coefficients ( FWC) is one of the key problems for the relevant research. It wasarbitrary and subjective to some extent presently. To overcome this difficulty, thereasonable assumptions were given for the observation field and analyzed field, variationalproblems with " weak constraints" and " strong constraints" were considered separately. Bysolving Euler' s equation with the matrix theory and the finite difference method of partialdifferential equation, the objective weight coefficients were obtained in the minimumvariance of the difference between the analyzed field and ideal field. Deduction results showthat theoretically the optimal selection indeed exists in the weighting factors of the costfunction in the means of the minimal variance between the analysis and ideal field in terms ofthe matrix theory and partial differential ( corresponding difference ) equation, if thereasonable assumption from the actual problem is valid and the differnece equation is *** may realize the coordination among the weight factors, numerical models and theobservational data. With its theoretical basis as well as its prospects of applications, thisobjective selecting method is probably a way towards the finding of the optimal weightingfactors in the variational problem.

关键词： constraint variation weight minimum variance

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EFFECT OF BROADCAST AND PRECISE EPHEMERIDES ON ESTIMATES OF THE FREQUENCY STABILITY OF GPS NAVSTAR CLOCKS

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INTERNATIONAL JOURNAL OF SATELLITE COMMUNICATIONS 1994年第5期12卷 435-441页

作者： MCCASKILL, TB REID, WG BUISSON, JA WARREN, HE U.S. Naval Research Laboratory Naval Centre for Space Technology Space Applications Branch Washington DC 20375–5320 USA. A physicist who has worked with the Space Applications Branch of the Naval Research Laboratory (NRL) since 1960. He works in the areas of precise time and frequency and satellite navigation. His satellite navigation work began in 1966 with the TIM-ATION program. He developed navigation algorithms that were used in the design of the NRL-proposed constellation for GPS. He has been a member of the GPS team for more than 20 years. His current work involves the frequency stability analysis of all GPS Navstar and monitor station clocks. An Electronics Engineer who has worked at the Naval Research Laboratory since 1971 and with the Space Applications Branch since 1983. He has been a member of the GPS team for more than a decade. His current work involves software development for the clock analysis program and analysis of the Navstar clock behaviour in the areas of anomaly detection correction of breaks in the data frequency stability and spectral analysis. SFA Inc. 1401 McCormick Drive Landover MD 20785 USA. A physicist who has been associated with the Naval Research Laboratory since 1960 and currently is an independent contractor. He has worked on the GPS project for more than 20 years. He was involved with the first experiment in the TIMATION program in 1964 and with the design of the NRL-proposed constellation for GPS. He was the Director of the Control Center for the Navigation Technology Segment (NTS) of GPS which verified key concepts that included precise time transfer navigation and the relativistic clock effect for GPS. An engineer who has been associated with the Space Applications Branch of the Naval Research Laboratory since 1959–first with Bendix Field Engineering until 1990 and currently with SFA Inc. His work includes GPS precise time and frequency measurements for NTS and GPS data communications and analysis of the Navstar clocks.

Frequency stability analysis of on-orbit Navstar clocks is performed by the Naval Research laboratory using both the broadcast and the precise post-processed ephemerides. The phase offset between the Navstar clock and the reference clock is computed from pseudorange measurements obtained by dual-frequency GPS receivers at the five GPS monitor sites and at the U.S. Naval Observatory precise-time site. The broadcast ephemerides are generated at the GPS master control station by a Kalman filter using data collected from the five GPS monitor stations. The precise post-processed ephemerides are generated by the Defense Mapping Agency (DMA) using data collected from the GPS monitor sites and from five additional DMA monitor sites. In this paper the frequency stability is estimated for two Navstar caesium clocks-a Block I caesium clock (Navstar 9) and a Block II caesium clock (Navstar 23)-using both the broadcast and the precise ephemerides. A significant improvement in the estimate of the frequency stability of the Block II clocks has been achieved using the precise ephemeris.

关键词： GPS NAVSTAR CLOCKS FREQUENCY STABILITY BROADCAST AND PRECISE EPHEMERIDES EPHEMERIS PREDICTION UNCERTAINTY

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