Study on short-range numerical forecasting of ocean current in the East China Sea-Ⅲ Three-dimensional baroclinic anomaly forecasting model and its application

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Observing spectral characteristics over a continental shelf and slope in the South China Sea

Using in situ measurement data from May-June, 1998, and data from the Asian seas international acoustics experiment （ASIAEX） from 2001 in the South China Sea （SCS）, the spectral density function and the dissipa- tion spectrum function are estimated. In the inffa-gravity wave （IGW） band, the power spectra of velocity （u, v, w） are universal functions with respect to characteristic frequencies, which correspond to the peak fre- quencies of the dissipation spectrum （PFDS）. This suggests that high-frequency internal waves in the IGW band have similar dynamical characteristics. In addition, the evolution of these characteristic frequencies is explored and its highest value is 8.8 cph （cycles per hour, 1 cph=2.778× 10-3 Hz）.     

基于EOF分析对南海西北海域水体光谱特性的研究

This study presents an analysis of the spectral characteristics of remote sensing reflectance(R_(rs)) in northwestern South China Sea based on the in situ optical and water quality data for August 2018.R_(rs)was initially divided into four classes,classes A to D,using the max-classification algorithm,and the spectral properties of whole R_(rs) were characterized using the empirical orthogonal function(EOF) analysis.Subsequently,the dominant factors in each EOF mode were determined.The results indicated that more than 95% of the variances of R_(rs) are partly driven by the back-scattering characteristics of the suspended matter.The initial two EOF modes were well correlated with the total suspended matter and back-scattering coefficient.Furthermore,the first EOF modes of the four classes of R_(rs)(A-D R_(rs)-EOF_1) significantly contributed to the total variances of each R_(rs) class.In addition,the correlation coefficients between the amplitude factors of class A-D R_(rs)-EOF_1 and the variances of the relevant water quality and optical parameters were better than those of the unclassified ones.The spectral shape of class AR_(rs)-EOF_1 was governed by the absorption characteristic of chlorophyll a and colored dissolved organic matter(CDOM).The spectral shape of class B R_(rs)-EOF_1 was governed by the absorption characteristic of CDOM since it exhibited a high correlation with the absorption coefficient of CDOM(a_g(λ)),whereas the spectral shape of class C R_(rs)-EOF_1 was governed by the back-scattering characteristics but not affected by the suspended matter.The spectral shape of class D R_(rs)-EOF_1 exhibited a relatively good correlation with all the water quality parameters,which played a significant role in deciding its spectral shape.     

Evaluation of a regional climate model using in situ temperature observations over the Balkan Peninsula

Climate model data provide large, dense coverage and long time-series, characteristics that are advantageous in the study of climate. However, it is not recommended that such data be used in any region without prior evaluation of their reliability based on comparisons with in situ observations. In this study, the accuracy of maximum and minimum temperature data from the ALADIN-Climate regional climate model (with a 25-km horizontal resolution driven at the lateral boundaries by the ERA-40 reanalysis) have been assessed for 53 stations across the Balkan Peninsula. The model temperatures corresponding to each station were extracted from their nearest land grids. The model data were first compared with observations and subsequently examined for their ability to identify extreme temperature events. In general, the model was found to be quite accurate in describing the seasonal cycle, as well as simulating the spatial distribution of temperature. Simulations were more realistic for stations along coastlines, highlighting the constraints of the topographic forcing in the simulations. Assessing the performance of the model to determine extremes (warm and cold spells), it was found to be better at detecting cold spells and has a tendency toward overestimating the frequency of occurrence of warm spells, particularly in summer.     

Vertical structure variability in a seasonal simulation of a medium-resolution regional model of the Eastern South Pacific

A seasonal simulation from a medium-resolution ocean general circulation mode (OGCM) is used to investigate the vertical structure variability of the Southeast Pacific (SEP). The focus is on the extra-tropical Rossby wave (ETRW) variability and associated forcing mechanism. Some aspects of the model mean state are validated from available observations, which justifies a vertical mode decomposition of the model variability. The analysis of the baroclinic mode contributions to sea level indicates that the gravest mode is dominant over most of the domain at all frequencies. Annual variability is on average twice as large as the semi-annual variability which is confined near the coast for all the modes. The first baroclinic mode contribution to the annual cycle exhibits a clear westward propagation north of the critical latitude. The higher-order modes only contribute near the coast where they are associated with vertically propagating energy. The residual variability, which is the energy at all timescales other than annual and semi-annual periods peaks offshore between 20°S and 30°S for all baroclinic modes. The third baroclinic mode also exhibits a relative maximum variability off the coast of Peru south of the critical latitude of the annual cycle (13°S), where the Peru–Chile Undercurrent is the most intense. Sensitivity experiments to the atmospheric and boundary forcing suggest that the residual variability results from the non-linear interaction between annual Rossby waves and the mean flow, while the annual ETRWs in the model result from the summed-contribution from both the local wind stress and remote equatorial forcing. Overall the study extends the classical analysis of sea level variability in the SEP based on linear theory, and suggests that the peculiarities of the baroclinic modes need to be taken into account for interpreting the sea level variability and understanding its connection with the equatorial variability.     

Study on short-range numerical forecasting of ocean current in the East China Sea Ⅱ. Three-dimensional diagnostic model and its application in the Bohai Sea

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南海及邻近海域大气-海浪-海洋耦合精细化数值预报系统研制

本文主要介绍了南海及邻近海域大气-海浪-海洋耦合精细化数值预报系统的研制概况。预报区域为99°E~135°E,15°S~45°N,包括渤海、黄海、东海和南海及其周边海域。为了给耦合预报模式提供较准确的预报初始场,在预报开始之前,分别进行了海浪模式和海洋模式的前24小时同化后报模拟。海浪模式和海洋模式都采用了集合调整Kalman滤波同化方法,海浪模式同化了Jason-2有效波高数据;海洋模式同化了SST数据、MADT数据和ARGO剖面数据。为了改进海洋温度和盐度的模拟,我们在海洋模式的垂向混合方案中引入波致混合和内波致混合的作用。预报系统的运行主要包括两个阶段,首先海浪模式和海洋模式进行了2014年1月至2015年10月底的同化后报模拟,强迫场源自欧洲气象中心的六小时的再分析数据产品。然后耦合预报系统将同化后报模拟的结果作为初始场进行了14个月的耦合预报。预报产品包括大气产品（气温、风速风向、气压等）、海浪产品（有效波高和波向等）、海流产品（温度、盐度和海流等）。一系列观测资料的检验比较表明该大气-海浪-海洋耦合精细化数值预报系统的预报结果较为可靠,可以为南海及周边海洋资源开发和安全保障提供数据和信息产品服务。     

一次粤西沿海地区强降水成因与GRAPES预报表现

利用NCEP 4次/d的1°×1°FNL再分析资料、自动站资料、多普勒天气雷达资料、GRAPES_36 km模式预报资料,从天气学的角度分析研究了2010年6月28日强降水的成因.分析结果表明,此次强降水系由于南海季风槽建立造成,实况形势分析和物理量场诊断都符合南海季风槽的特征.强降水的辐合上升运动十分之明显,水汽辐合高值区与暴雨落区一致,强降水伴随南海季风槽建立同时发生.GRAPES_36 km模式对此次季风槽形势预报、物理结构描述得相当清晰,暴雨落区对应的高能区、强烈辐合区,模式描述相当准确,模式的提前量能够保证对此次季风槽造成的强降水作出提前预报.     

Study on short-range numerical forecasting of ocean current in the East China Sea——Ⅰ Basic problems of ocean current forecasting and structure of the models

Ocean current forecasting is still in explorative stage of study. In the study, we face some problems that have not been met before. The solving of these problems has become fundamental premise for realizing the ocean current forecasting. In the present paper are discussed in depth the physical essence for such basic problems as the predictability of ocean current, the predictable currents, the dynamical basis for studying respectively the tidal current and circulation, the necessity of boundary model, the models on regions with different scales and their link. The foundations and plans to solve the problems are demonstrated. Finally a set of operational numerical forecasting system for ocean current is proposed.     

A comparison of summer precipitation structures over the South China Sea and the East China Sea based on tropical rainfall measurementmission

The three-dimensional structures of summer precipitation over the South China Sea （SCS） and the East China Sea （ECS） are investigated based on tropical rainfall measurement mission （TRMM）. The primary results are as follows. First, both the convective and stratiform precipitation rates in the SCS are much higher than those of the ECS. The contribution of the convective cloud precipitation to the surface precipitation is primarily over the SCS and the ECS with a proportion of about 70%, but the contribution of convective cloud precipitation is slightly larger in the SCS than the ECS. The contribution of stratus precipitation is slightly larger in the ECS than that in the SCS. Second, the content of cloud particles and precipitation particles in the ECS in June was greater than that in the SCS, while in July and August, the content of cloud and precipitation particles in the ECS was less than that in the SCS. Third, the latent heat profile of the ECS is quite different from that of the SCS. In June, the peak values of evaporation and condensation latent heating rates in the ECS are greater than those in the SCS. In July and August, however, the peak values of evaporation and condensation latent heating rates in the ECS are about 0.05°/h less than those in the SCS.     

The impact of mean dynamic topography on a sea-level anomaly assimilation in the South China Sea based on an eddy-resolving model

The sea-level anomaly (SLA) from a satellite altimeter has a high accuracy and can be used to improve ocean state estimation by assimilation techniques. However, the lack of an accurate mean dynamic topography (MDT) is still a bothersome issue in an ocean data assimilation. The previous studies showed that the errors in MDT have significant impacts on assimilation results, especially on the time-mean components of ocean states and on the time variant parts of states via nonlinear ocean dynamics. The temporal-spatial differences of three MDTs and their impacts on the SLA analysis are focused on in the South China Sea (SCS). The theoretical analysis shows that even for linear models, the errors in MDT have impacts on the SLA analysis using a sequential data assimilation scheme. Assimilation experiments, based on EnOI scheme and HYCOM, with three MDTs from July 2003 to June 2004 also show that the SLA assimilation is very sensitive to the choice of different MDTs in the SCS with obvious differences between the experimental results and observations in the centre of the SCS and in the vicinity of the Philippine Islands. A new MDT for assimilation of SLA data in the SCS was proposed. The results from the assimilation experiment with this new MDT show a marked reduction (increase) in the RMSEs (correlation coefficient) between the experimental and observed SLA. Furthermore, the subsurface temperature field is also improved with this new MDT in the SCS.     

Maritime issues in North-East Asia: Their impact on regional politics

The author provides an introduction to the politics of the North-east Asia region, a survey of local maritime issues and disputes, and examines the impact of the new ocean regime on this region. He concludes that, although there are many substantial maritime disputes in North-east Asia, these are in general subordinated to larger determinants of political relations, and do not themselves have a major impact on regional politics. Soviet—Japanese relations, however, constitute an exception to this rule. Dr Buzan argues that the disputes over fishing and the northern islands played a key role in impeding better Soviet-Japanese relations, and thereby facilitated the current Sino — Japanese rapprochement with its potentially global implications.     

Assessing the impact of pollution on aquatic systems at a global and regional level

In developing a methodology for the ongoing Global International Waters Assessment, major gaps have become apparent in our ability to make comparative assessments of pollution. A pragmatic impacts scoping methodology has been developed and tested. A more effective assessment protocol however, requires a better knowledge of the relationship between pollution sources and biological effects with less reliance on chemical monitoring.     

南海区高分辨率非线性耦合作用台风风暴潮数值预报试验与研究

本文对适用于南海区多因素影响的二级粗细嵌套网格风暴潮模型进行开发研究,考虑目前计算条件限制和预报实际时效的需要,采用天文潮与风暴潮的非线性相互作用二级模型进行风暴潮潮位实验研究.本文的研究改进现有风暴潮模式中仅考虑风与气压影响增减水的缺陷,考虑了天文潮的非线性影响风暴潮潮位等因素,预报出实时风暴潮潮位,与目前多因素海洋动力耦合模型有相似之处.更好地提高了风暴潮增减水及实时潮位的预报精度,给出直观的近岸海域风暴潮潮位时空分布.     

基于浙江海堤安全的海洋环境因子变化研究

海堤工程是防御风暴潮侵袭、减轻海洋灾害的重要工程措施。海洋环境科学与工程技术研究不断发展,特别是海洋环境、海岸动力学和海岸地貌学等多学科交叉研究,海洋水文等资料不断积累和工程实践经验的日益丰富,为我国推进海堤抵御风暴潮灾害等安全研究和工程实践提供了有利条件。通过分析历史监测数据研究了浙江海岸滩地高程、年最高潮位、风浪、台风暴潮、海平面上升等海洋环境因子的变化趋势,与浙江省技术规范比较表明,近几十年来这些因子变化幅度不断加大,这种变化趋势说明受海洋环境影响,海堤安全面临挑成。     

不规则波对浪溅区结构物冲击作用的试验研究——频域分析

对不规则波对浪溅区结构物的冲击作用实验结果进行了谱分析研究。给出了不同试验组次的结构物底面所受波浪冲击压力的谱分析结果，得到了结构物底面所受波浪冲击压力的谱矩m0沿结构物底面的分布规律，讨论了入射波波要素和结构物底面距静水面的相对高度s/H1/3对作用于结构物底面的冲击压力谱矩m0,avg的影响，给出了平均冲击压力谱矩m0,svg.与统计分析的压力特征值Pc的关系。     

一个区域海洋——海冰——大气耦合模式中的北极气候偏差：年结果检验

The Coupling of three model components, WRF/PCE （polar climate extension version of weather research and forecasting model （WRF））, ROMS （regional ocean modeling system）, and CICE （community ice code）, has been implemented, and the regional atmosphere-ocean-sea ice coupled model named WRF/PCE- ROMS-CICE has been validated against ERA-interim reanalysis data sets for 1989. To better understand the reasons that generate model biases, the WRF/PCE-ROMS-CICE results were compared with those of its components, the WRF/PCE and the ROMS-CICE. There are cold biases in surface air temperature （SAT） over the Arctic Ocean, which contribute to the sea ice concentration （SIC） and sea surface temperature （SST） biases in the results of the WRF/PCE-ROMS-CICE. The cold SAT biases also appear in results of the atmo- spheric component with a mild temperature in winter and similar temperature in summer. Compared to results from the WRF/PCE, due to influences of different distributions of the SIC and the SST and inclusion of interactions of air-sea-sea ice in the WRF/PCE-ROMS-CICE, the simulated SAT has new features. These influences also lead to apparent differences at higher levels of the atmosphere, which can be thought as responses to biases in the SST and sea ice extent. There are similar atmospheric responses in feature of distribution to sea ice biases at 700 and 500 hPa, and the strength of responses weakens when the pressure decreases in January. The atmospheric responses in July reach up to 200 hPa. There are surplus sea ice ex- tents in the Greenland Sea, the Barents Sea, the Davis Strait and the Chukchi Sea in winter and in the Beau- fort Sea, the Chukchi Sea, the East Siberian Sea and the Laptev Sea in summer in the ROMS-CICE. These differences in the SIC distribution can all be explained by those in the SST distributions. These features in the simulated SST and SIC from ROMS-CICE also appear in the WRF/PCE-ROMS-CICE. It is shown that the performance of the WRF/PCE-ROMS-CICE is determined to a l     

耦合模式中海浪参数对台风浪预报的影响研究

以西北太平洋一次"双台风"共同影响下的台风浪为例,针对模式中风摄入和白帽耗散、底摩擦、波破碎、波-波非线性相互作用等海浪物理过程对台风浪预报的影响进行了敏感性试验分析。在此基础上,基于各物理过程最优参数化方案探讨了耦合模式和单独海浪模式的海浪预报性能,分析了耦合模式的海浪预报场分布特征。结果表明:不同海浪物理过程参数化对于波高预报的准确性是有所差异的。在相对最优的海浪各参数化方案组合下,无论耦合模式还是单独海浪模式都能较好地反映波高的变化和分布趋势。相比而言,耦合模式对于台风浪大值区的浪高预报要比单独海浪模式的更接近观测,且可以很好地刻画出双台风影响下浪的分布演变特征,对于西太平洋台风浪的预报具有很好的适用性。