南海及周边海域风浪流耦合同化精细化数值预报与信息服务系统简介

面向社会需求,建立覆盖南海及周边海域的高分辨率风-浪-流耦合同化数值预报与信息服务系统。系统包含耦合同化数值预报模式、海洋动力环境数据库与可视化平台两部分。其中,耦合同化数值预报模式由中尺度大气数值预报模式、海浪数值预报模式和区域海洋环流数值模式,在C-Coupler耦合器中进行耦合,引入集合调整Kalman滤波同化模块,在耦合预报前进行大气、海浪和海流的同化后报模拟,为耦合预报模式提供更为精确的初始场。预报结果经海洋动力环境数据库和可视化平台处理后,通过二维和三维可视化展示,向用户提供直观的南海及周边海域海洋环境预报产品。     

Why does the IOD-ENSO teleconnection disappear in some decades?

Lag correlations between sea surface temperature anomalies(SSTA) in the southeastern tropical Indian Ocean(STIO) in fall and Nio 3.4 SSTA in the eastern equatorial Pacific in the following fall are subjected to decadal variation,with positive correlations during some decades and negative correlations during others. Negative correlations are smaller and of shorter duration than positive correlations. Variations in lag correlations suggest that the use of the Indian Ocean Dipole(IOD) as a predictor of the El Nio Southern Oscillation(ENSO) at a lead time of one year is not effective during some decades. In this study,lag correlations between IOD and ENSO anomalies were analyzed to investigate why the IOD-ENSO teleconnection disappears during decades with negative correlations. Anomalies induced by the IOD in the equatorial Pacific Ocean during decades with negative correlations are still present,but at a greater depth than in decades with positive correlations,resulting in a lack of response to oceanic channel dynamics in the cold tongue SSTA. Lag correlations between oceanic anomalies in the west Pacific warm pool in fall and the equatorial Pacific cold tongue with a one-year time lag are significantly positive during decades with negative correlations. These results suggest that oceanic channel dynamics are overwhelmed by oceanatmosphere coupling over the equatorial Pacific Ocean during decades with negative correlations. Therefore,the Indonesian throughflow is not effective as a link between IOD signals and the equatorial Pacific ENSO.     

东海区域海洋学调查研究回顾

由于近几十年来日益增强的人类活动影响,近海海洋环境较过去发生了巨大变化;科学认知近海海洋环境特征、变化和控制因素对于应对全球变化具有重要意义,是当前海洋学关注的重要议题。东海作为中国重要的海洋区域之一,存在独特的环流系统,孕育了大河口、上升流和黑潮三个代表性的生态系统,其海洋科学研究对于我国的海洋资源开发、环境保护和国家安全具有重要意义。本文通过对东海区域海洋学研究的现状进行综述,围绕海洋生物地球化学这一主线,重点总结了物理海洋学、海洋化学、海洋地质学和生物海洋学的相关研究进展,分析了目前存在的问题,并展望了未来的发展方向。研究表明,东海区域海洋环境受到人类活动和气候变化的深刻影响,呈现新的变化格局;长江径流输入、黑潮北上及其入侵陆架是东海三大生态系统格局形成的主要驱动力。除主要的环流结构外,穿刺锋面和跨陆架海流是连接东海内陆架和外陆架水体的主要动力过程,并促进了碳等重要生源物质的跨陆架输送。相关研究在海洋生态环境、应对气候变化、海洋灾害等方面取得了一定的成果,但仍面临着数据不足、研究领域不够广泛等挑战。东海海洋环境在时间和空间上变化均较大,且存在近岸富营养化、大河口低氧现象等主要环境...     

An assessment of Indo-Pacific oceanic channel dynamics in the FGOALS-g2 coupled climate system model

Lag correlations of sea surface temperature anomalies (SSTAs), sea surface height anomalies (SSHAs), subsurface temperature anomalies, and surface zonal wind anomalies (SZWAs) produced by the Flexible Global Ocean-Atmosphere-Land System model: Grid-point Version 2 (FGOALS-g2) are analyzed and compared with observations. The insignificant, albeit positive, lag correlations between the SSTAs in the southeastern tropical Indian Ocean (STIO) in fall and the SSTAs in the central-eastern Pacific cold tongue in the following summer through fall are found to be not in agreement with the observational analysis. The model, however, does reproduce the significant lag correlations between the SSHAs in the STIO in fall and those in the cold tongue at the one-year time lag in the observations. These, along with the significant lag correlations between the SSTAs in the STIO in fall and the subsurface temperature anomalies in the equatorial Pacific vertical section in the following year, suggest that the Indonesian Throughflow plays an important role in propagating the Indian Ocean anomalies into the equatorial Pacific Ocean. Analyses of the interannual anomalies of the Indonesian Throughflow transport suggest that the FGOALS-g2 climate system simulates, but underestimates, the oceanic channel dynamics between the Indian and Pacific Oceans. FGOALS-g2 is shown to produce lag correlations between the SZWAs over the western equatorial Pacific in fall and the cold tongue SSTAs at the one-year time lag that are too strong to be realistic in comparison with observations. The analyses suggest that the atmospheric bridge over the Indo-Pacific Ocean is overestimated in the FGOALS-g2 coupled climate model.     

南海北部东沙岛附近海洋底层流场特征及时间变化规律

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.     

北赤道流分岔点与印尼贯穿流的相关分析

Based on monthly mean Simple Ocean Data Assimilation(SODA) products from 1958 to 2007,this study analyzes the seasonal and interannual variability of the North Equatorial Current(NEC) bifurcation latitude and the Indonesian Throughflow(ITF) volume transport. Further,Empirical Mode Decomposition(EMD) method and lag-correlation analysis are employed to reveal the relationships between the NEC bifurcation location,NEC and ITF volume transport and ENSO events. The analysis results of the seasonal variability show that the annual mean location of NEC bifurcation in upper layer occurs at 14.33°N and ITF volume transport has a maximum value in summer,a minimum value in winter and an annual mean transport of 7.75×106 m3/s. The interannual variability analysis indicates that the variability of NEC bifurcation location can be treated as a precursor of El Ni?o. The correlation coefficient between the two reaches the maximum of 0.53 with a time lag of 2 months. The ITF volume transport is positively related with El Ni?o events with a maximum coefficient of 0.60 by 3 months. The NEC bifurcation location is positively correlated with the ITF volume transport with a correlation coefficient of 0.43.     

南海等密度面环流季节变化的数值模拟研究

In this study, we develop a variable-grid global ocean general circulation model(OGCM) with a fine grid(1/6)°covering the area from 20°S–50°N and from 99°–150°E, and use the model to investigate the isopycnal surface circulation in the South China Sea(SCS). The simulated results show four layer structures in vertical: the surface and subsurface circulation of the SCS are characterized by the monsoon driven circulation, with basin-scaled cyclonic gyre in winter and anti-cyclonic gyre in summer. The intermediate layer circulation is opposite to the upper layer, showing anti-cyclonic gyre in winter but cyclonic gyre in summer. The circulation in the deep layer is much weaker in spring and summer, with the maximum velocity speed below 0.6 cm/s. In fall and winter, the SCS deep layer circulation shows strong east boundary current along the west coast of Philippine with the velocity speed at 1.5 m/s, which flows southward in fall and northward in winter. The results have also revealed a fourlayer vertical structure of water exchange through the Luzon Strait. The dynamics of the intermediate and deep circulation are attributed to the monsoon driving and the Luzon Strait transport forcing.     

海洋模式中潮致混合调和分析参数化方案的建立

潮致混合对海洋环流的调整起着重要作用。陆架环流的数值模拟中如果不考虑潮汐作用,往往不能得到与观测相符的垂向温盐结构。本文基于调和分析方法,建立了一套潮致混合参数化方案。该方案通过对垂向混合系数进行调和分析,从而得到随时间变化的潮致混合系数。将该方案用于黄海冷水团数值模拟的结果显示,其能够得到与在数值模式开边界直接加入潮汐强迫相当的冷水团温盐结构。和直接引入潮汐强迫相比,这一潮致混合参数化方案的优势在于,它能够大大节省数值模拟计算机时,因此有望显著提高大规模高分辨率的海洋环流及气候模式的模拟能力和计算效率。     

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。     

进入中国南海的黑潮脱落中尺度涡的特征——基于OFES模式数据

自黑潮脱落并由吕宋海峡进入中国南海的中尺度涡(简称脱落涡旋)对黑潮与南海的水体交换、热量及物质输送等过程均有十分重要的作用.基于1993—2013年OFES(OGCM for the Earth Simulator)模式数据产品,分析研究了脱落涡旋的统计特征及其温盐流三维结构,并与卫星观测结果进行对比分析.OFES模式...