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NON-LINEAR DYNAMIC MODEL RETRIEVAL OF SUBTROPICAL HIGH BASED ON empirical orthogonal function AND GENETIC ALGORITHM

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Applied Mathematics and Mechanics(English Edition) 2006年第12期27卷 1645-1653页

作者：张韧洪梅孙照渤牛生杰朱伟军闵锦忠万齐林 Institute of Meteorology PLA University of Science and TechnologyNanjing 211101P. R. China Nanjing University of Information Science & Technology KLMENanjing 210044P. R. China Institute of Tropical and Marine Meteorology CMAGuangzhou 510080P. R. China

Aiming at the difficulty of accurately constructing the dynamic model of subtropical high, based on the potential height field time series over 500 hPa layer of T106 numerical forecast products, by using EOF（empirical orthogonal function） temporal-spatial separation technique, the disassembled EOF time coefficients series were regarded as dynamical model variables, and dynamic system retrieval idea as well as genetic algorithm were introduced to make dynamical model parameters optimization search, then, a reasonable non-linear dynamic model of EOF time-coefficients was established. By dynamic model integral and EOF temporal-spatial components assembly, a mid-/long-term forecast of subtropical high was carried out. The experimental results show that the forecast results of dynamic model are superior to that of general numerical model forecast results. A new modeling idea and forecast technique is presented for diagnosing and forecasting such complicated weathers as subtropical high.

关键词： genetic algorithm empirical orthogonal function non-linear model retrieval subtropical high

The low-frequency variance of the ocean surface wave field in the area of the Antarctic Circumpolar Current

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Acta Oceanologica Sinica 2013年第5期32卷 15-21页

作者： ZHANG Xiaoshuang WU Kejian WANG Bin WANG Zhifeng Ocean University of China Key Laboratory of Marine Environmental Information Technology National Marine Data and Information ServiceState Oceanic Administration Physical Oceanography Laboratory Ocean University of China

The low-frequency variance of the surface wave in the area of the Antarctic Circumpolar Current （ACC） and its correlation with the antarctic circumpolar wave （ACW） are focused on. The analysis of the series of 44 a significant wave height （SWH） interannual anomalies reveals that the SWH anomalies have a strong periodicity of about 4-5 a and this signal propagates eastward obviously from 1985 to 1995, which needs about 8 a to complete a mimacircle around the earth. The method of empirical orthogonal function （EOF） is used to analyze the filtered monthly SWH anomalies to study the spatio-temporal distributions and the propagation characteristics of the low-frequency signals in the wave field. Both the dominant wavenumber- 2 pattern in space and the propagation feature in the south Pacific, the south Atlantic and the south Indian ocean show strong consistency with the ACW. So it is reasonable to conclude that the ACW signal also exists in the wave field. The ACW is important for the climate in the Southern Ocean, so it is worth to pay more attention to the large- scale effect of the surface wave, which may also be important for climate studies.

关键词： significant wave height antarctic circumpolar wave empirical orthogonal function low-frequ-ency variance

Impact of Urbanization on Low-Temperature Precipitation in Beijing during 1960–2008

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Advances in Atmospheric Sciences 2014年第1期31卷 48-56页

作者： HAN Zuoqiang YAN Zhongwei LI Zhen LIU Weidong WANG Yingchun Key Laboratory of Regional Climate–Environment for Temperate East Asia Institute of Atmospheric Physics Chinese Academy of Sciences Graduate University of Chinese Academy of Science Institute of Urban Meteorology China Meteorological Administration

Daily precipitation and temperature records at 13 stations for the period 1960-2008 were analyzed to identify climatic change and possible effects of urbanization on low-temperature precipitation [LTP, precipitation of ≥ 0.1 mm d^-1 occurring under a daily minimum temperature （Tmin） of ≤ 0℃] in the greater Beijing region （B JR）, where a rapid process of urbaniza tion has taken place over the last few decades. The paper provides a climatological overview of LTP in B JR. LTP contributes 61.7% to the total amount of precipitation in B JR in the cold season （November-March）. There is a slight increasing trend [1.22 mm （10 yr）^-1] in the amount of total precipitation for the cold season during 1960-2008. In contrast, the amount of LTP decreases by 0.6 mm （10 yr）^-1. The warming rate of Train in B JR is 0.66℃ （10 yr）^-1. Correspondingly, the frequency of LTP decreases with increasing Tmin by -0.67 times per ℃. The seasonal frequency and amount of LTP in southeast B JR （mostly urban sites） are 17%-20% less than those in the northwestern （rural and montane sites）. The intensity of LTP for the urban sites and northeastern B JR exhibited significant enhancing trends [0.18 and 0.15 mm d^- 1 （10 yr）^- 1, respectively]. The frequency of slight LTP （〈0.2 mm d^-1） significantly decreased throughout B JR [by about -15.74% （10 yr）^-1 in the urban area and northeast B JR], while the contribution of the two heaviest LTP events to total LTP amount significantly increased by 3.2% （10 yr） ^-1.

关键词： urbanization low-temperature precipitation empirical orthogonal function climate change

Performance of a data-driven technique applied to changes in wave height and its effect on beach response

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Water Science and Engineering 2016年第1期9卷 42-51页

作者： José M.Horrillo-Caraballo Harshinie Karunarathna Shun-qi Pan Dominic Reeve Energy&Environment Research Group Zienkiewicz Centre for Computational EngineeringSwansea UniversityBay CampusSwansea SA1 8ENUK Hydro-environmental Research Centre School of EngineeringCardiff UniversityCardiff CF24 3AAUK

In this study the medium-term response of beach profiles was investigated at two sites： a gently sloping sandy beach and a steeper mixed sand and gravel beach. The former is the Duck site in North Carolina, on the east coast of the USA, which is exposed to Atlantic Ocean swells and storm waves, and the latter is the Milford-on-Sea site at Christchurch Bay, on the south coast of England, which is partially sheltered from Atlantic swells but has a directionally bimodal wave exposure. The data sets comprise detailed bathymetric surveys of beach profiles covering a period of more than 25 years for the Duck site and over 18 years for the Milford-on-Sea site. The structure of the data sets and the data-driven methods are described. Canonical correlation analysis （CCA） was used to find linkages between the wave characteristics and beach profiles. The sensitivity of the linkages was investigated by deploying a wave height threshold to filter out the smaller waves incrementally. The results of the analysis indicate that, for the gently sloping sandy beach, waves of all heights are important to the morphological response. For the mixed sand and gravel beach, filtering the smaller waves improves the statistical fit and it suggests that low-height waves do not play a primary role in the medium-term morohological resoonse, which is primarily driven by the intermittent larger storm waves.

关键词： Beach profile Canonical correlation analysis Data-driven technique empirical orthogonal function Forecast Statistical model Wave height threshold

Numerical modeling on the interaction of internal solitary wave with slope-shelf and modal analysis

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Acta Oceanologica Sinica 2007年第6期26卷 139-149页

作者： LI Qun XU Zhaoting CHEN Xu YU Jia Physical Oceanography Laboratory and Institute of Physical Oceanography Ocean University of China Qingdao 266100 China

On the basis of a nonhydrostatic numerical model, the interaction of internal solitary wave with slope - shelf was studied. The breaking and polarity transformation were analyzed. A ＂kink＂ structure, due to shoaling topography and higher nonlinear effect, was found to be generated by the leading wave before breaking. Coherent vortex shedding behind the leading wave was presented. The evolution characteristics of the modal structure were analyzed based on the empirical orthogonal function method. The modal structure was complicated due to the effect of the variable topography, especially when breaking occurred. In the performed experiments, the contributions to the total variance from higher mode jumped from no more than 20% to over 40%.

关键词： internal solitary wave modal structure empirical orthogonal function

Global features and trends of the tropopause derived from GPS/CHAMP RO data

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Science China(Physics,Mechanics & Astronomy) 2011年第2期54卷 365-374页

作者： HAN TingTing PING JinSong ZHANG SuJun Shanghai Astronomical Observatory Chinese Academy of Sciences. Shanghai 200030. China Graduate Unviersity of Chinese Academy of Science s Beijing 100039 China

The global characteristics and trends of the tropopause physical parameters,height and temperature,obtained from the GPS/CHAMP radio occultation(RO) data in the period from Jul.2001 to Oct.2008,were modeled and analyzed in this *** global distribution and variation of these parameters with latitude were estimated and analyzed using the empirical orthogonal function(EOF),which was introduced to reveal the possible relationship between the tropopause variations and global climate *** tropopause height and temperature varied with *** results obtained by using the empirical orthogonal function analysis suggested a recent rise in tropopause height and decrease in tropopause temperature;and also partly supported the argument that the global rise in the tropopause is consistent with global climate *** results also revealed that the tropopause height increased mainly in the Polar regions,particularly in the South Polar region,as well as the regions where human activity is relatively significant,and decreased in the areas that are sparsely populated or have less human activity,such as the tropic region and south *** paper also confirms that the GPS/LEO RO data are more reliable and can be effectively used to analyze the tropopause physical parameters.

关键词： tropopause height and temperature latitude features trend empirical orthogonal function

Objective array design for three-dimensional temperature and salinity observation:Application to the South China Sea

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Acta Oceanologica Sinica 2022年第7期41卷 65-77页

作者： Mengxue Qu Zexun Wei Yanfeng Wang Yonggang Wang Tengfei Xu 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

In this study,a moored array optimization tool(MAOT)was developed and applied to the South China Sea(SCS)with a focus on three-dimensional temperature and salinity *** of the MAOT involves two steps:(1)deriving a set of optimal arrays that are independent of each other for different variables at different depths based on an empirical orthogonal function method,and(2)consolidating these arrays using a K-center clustering *** with the assumed initial array consisting of 17 mooring sites located on a 3°×3°horizontal grid,the consolidated array improved the observing ability for three-dimensional temperature and salinity in the SCS with optimization efficiencies of 19.03%and 21.38%,*** with an increased number of moored sites showed that the most cost-effective option is a total of 20 moorings,improving the observing ability with optimization efficiencies up to 26.54%for temperature and 27.25%for *** design of an objective array relies on the ocean phenomenon of interest and its spatial and temporal *** this study,we focus on basin-scale variations in temperature and salinity in the SCS,and thus our consolidated array may not well resolve mesoscale *** MAOT can be extended to include other variables and multi-scale variability and can be applied to other regions.

关键词： optimal array design observation system simulation experiment South China Sea empirical orthogonal function K-center clustering

Interpretation of sea surface wind interannual vector EOFs over the China seas

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Chinese Journal of Oceanology and Limnology 2010年第2期28卷 340-343页

作者：赵喜喜侯一筠齐鹏 Ocean University of China Institute of Oceanology Chinese Academy of Sciences

Using interpolation and averaging methods, we analyzed the sea surface wind data obtained from December 1992 to November 2008 by the scatterometers ERS-1, ERS-2, and QuikSCAT in the area of 2°N-39 °N, 105°E-130°E, and we reported the monthly mean distributions of the sea surface wind field. A vector empirical orthogonal function （VEOF） method was employed to study the data and three temporal and spatial patterns were obtained. The first interannual VEOF accounts for 26% of the interannual variance and displays the interannual variability of the East Asian monsoon. The second interannual VEOF accounts for 21% of the variance and reflects the response of China sea winds to E1 Nifio events. The temporal mode of VEOF-2 is in good agreement with the curve of the Nifio 3.4 index with a four-month lag. The spatial mode of VEOF-2 indicates that four months after an E1 Nifio event, the southwesterly anomalous winds over the northern South China Sea, the East China Sea, the Yellow Sea, and the Bohai Sea can weaken the prevailing winds in winter, and can strengthen the prevailing winds in summer. The third interannual VEOF accounts for 10% of the variance and also reflects the influence of the ENSO events to China Sea winds. The temporal mode of VEOF-3 is similar to the curve of the Southern Oscillation Index. The spatial mode of VEOF-3 shows that the northeasterly anomalous winds over the South China Sea and the southern part of the East China Sea can weaken the prevailing winds, and southwesterly anomalous winds over the northern part of the East China Sea, the Yellow Sea, and the Bohai Sea can strengthen the prevailing winds when E1 Nifio occurs in winter. If E1 Nifio happens in summer, the reverse is true.

关键词： scatterometer, wind empirical orthogonal function

A dipole mode at thermocline layer in the tropical Indian Ocean

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Acta Oceanologica Sinica 2003年第1期22卷 15-24页

作者：田纪伟刘慧卿钱维宏 Physical Oceanography Laboratory Ocean University of China (Ocean University of Qingdao)Qingdao 266003China Department of Atmospheric Sciences Peking UniversityBeijing 100871China

Temperature data at different layers of the past 45 years were studied and we found adiploe mode in the thermocline layer (DMT): anomalously cold sea temperature off the coast of Sumatra and warm sea temperature in the western Indian Ocean. First, we analyzed the temperature and the temperature anomaly (TA) along the equatorial Indian Ocean in different layers. This shows that stronger cold and warm TA signals appeared at subsurface than at the surface in the tropical Indian O-cean. This result shows that there may be a strong dipole mode pattern in the subsurface tropical Indian Ocean. Secondly we used empirical orthogonal functions (EOF) to analyze the TA at thermocline layer. The first EOF pattern was a dipole mode pattern. Finally we analyzed the correlations between DMT and surface tropical dipole mode (SDM), DMT and Nino 3 SSTA, etc. and these correlations are strong.

关键词： Temperature anomaly dipole mode in thermocline layer tropical Indian Ocean empirical orthogonal function