基于扩散滤波的多尺度三维变分研究

将扩散方程引入三维变分分析,揭示了传统3D-VAR不能有效提取多尺度观测信息的根本原因,即观测导致的目标函数梯度在空间的不连续分布.将扩散滤波融入基于梯度的最优化算法,发展了基于扩散滤波的多尺度3D-VAR.海表面温度数据同化试验结果表明,新方法可从长波至短波有效地提取多尺度的观测信息.     

Impact of sea spray on upper ocean temperature during typhoon passage: simulation with a 1-D turbulent model

At the interface between the lower atmosphere and sea surface, sea spray might significantly influence air-sea heat fluxes and subsequently, modulate upper ocean temperature during a typhoon passage. The effects of sea spray were introduced into the parameterization of sea surface roughness in a 1-D turbulent model, to investigate the effects of sea spray on upper ocean temperature in the Kuroshio Extension area, for the cases of two real typhoons from 2006, Yagi and Soulik. Model output was compared with data from the Kuroshio Extension Observatory (KEO), and Reynolds and AMSRE satellite remote sensing sea surface temperatures. The results indicate drag coefficients that include the spray effect are closer to observations than those without, and that sea spray can enhance the heat fluxes (especially latent heat flux) considerably during a typhoon passage. Consequently, the model results with heat fluxes enhanced by sea spray simulate better the cooling process of the SST and upper-layer temperature profiles. Additionally, results from the simulation of the passage of typhoon Soulik (that passed KEO quickly), which included the sea spray effect, were better than for the simulated passage of typhoon Yagi (that crossed KEO slowly). These promising 1-D results could provide insight into the application of sea spray in general circulation models for typhoon studies.     

中国海及邻近海域卫星观测资料同化试验

利用1个基于POMgcs海洋模式和多重网格三维变分同化方法建立的中国海及邻近海域海面高与三维温盐流数值预报模型,通过一系列数值试验,研究了同化卫星测高和卫星遥感海面温度观测资料对该模型预报能力的影响。试验结果表明,同化卫星测高资料可明显改善海面高度与三维温度和盐度的分析预报效果,使1 200 m以上的温度预报误差减小0.16℃,并能有效提高对海洋中尺度现象的预报能力;同化卫星遥感海面温度对100 m以上的温度和盐度的预报效果有所改善,可使海面温度的预报误差减小10%。     

集合数据同化方法的发展与应用概述

集合数据同化方法具有简洁概念化的公式和应用起来相对容易等优点,因此,它们获得了普及性的应用;近10年来集合数据同化方法已经得到了快速的发展。综述了包括集合卡尔曼滤波(EnKF,Ensemble Kalman Filter)、集合卡尔曼平滑(EnKS,Ensemble Kalman Smoother)、集合方均根滤波(EnSRF,Ensemble Square-Root Filter)和减秩卡尔曼滤波(SEEK,Singular Evolutive Extended Kalman Filter)等集合数据同化方法的研究进展状况。通过与其它数据同化方法的对比,总结出了这些方法的特点,探讨了我国在集合数据同化方法研究中存在的问题并展望了该方法的研究和应用前景。     

国土资源数据分析及其整合与集成

本文详细分析了国土资源数据特点、综合数据来源、产生方式和使用方法等方面,对数据进行了分类,比较了不同的数据格式。在此基础上,阐述了国土资源数据的集成框架,讨论了数据整合和集成的方法和流程,提出了数据整合与集成的三种框架问题。     

胶州湾五河口互花米草群落扩展趋势及治理策略

近年来,胶州湾五河口区域互花米草群落扩展迅速。为分析互花米草群落的扩展趋势,利用2009年以来5个年度卫星历史影像,勾绘互花米草群落图斑并统计其扩展面积,分析其扩展趋势以及对生态环境的影响。结果表明:(1) GoogleEarth软件具有强大的历史影像数据库,可以快速查询1984年以来互花米草的历史影像资料,根据勾绘图斑计算面积,分析图斑消长变化;(2) 8年间,胶州湾五河口区域互花米草从无到有,群落面积现已扩展到215 hm~2;(3)预测在没有人为干预的情况下,2020年互花米草群落面积可扩展到500 hm~2;(4)以机械收割作为饲料或在萌芽期摘芽作为蔬菜等利用方式可以控制互花米草群落蔓延。     

海洋数据同化与数据融合技术应用综述

简述了不同数据同化和数据融合方法在海洋环境监测与预测方面的应用、国内外相关业务单位的海洋分析和预报系统的现状,以及海洋数据同化将来的业务化应用的发展趋势。四维变分和集合卡尔曼滤波正在成为国际上海洋环境分析与预报的主要应用方向,海-气耦合数据同化以及海冰数据同化是目前数据同化方法研究的热点。     

A global ocean reanalysis product in the China Ocean Reanalysis (CORA) project

The first version of a global ocean reanalysis over multiple decades (1979–2008) has been completed by the National Marine Data and Information Service within the China Ocean Reanalysis (CORA) project. The global ocean model employed is based upon the ocean general circulation model of the Massachusetts Institute of Technology. A sequential data assimilation scheme within the framework of 3D variational (3DVar) analysis, called multi-grid 3DVar, is implemented in 3D space for retrieving multiple-scale observational information. Assimilated oceanic observations include sea level anomalies (SLAs) from multi-altimeters, sea surface temperatures (SSTs) from remote sensing satellites, and in-situ temperature/salinity profiles. Evaluation showed that compared to the model simulation, the annual mean heat content of the global reanalysis is significantly approaching that of World Ocean Atlas 2009 (WOA09) data. The quality of the global temperature climatology was found to be comparable with the product of Simple Ocean Data Assimilation (SODA), and the major ENSO events were reconstructed. The global and Atlantic meridional overturning circulations showed some similarity as SODA, although significant differences were found to exist. The analysis of temperature and salinity in the current version has relatively larger errors at high latitudes and improvements are ongoing in an updated version. CORA was found to provide a simulation of the subsurface current in the equatorial Pacific with a correlation coefficient beyond about 0.6 compared with the Tropical Atmosphere Ocean (TAO) mooring data. The mean difference of SLAs between altimetry data and CORA was less than 0.1 m in most years.     

寒区再生集料水泥稳定碎石路基的力学和温缩性能北大核心CSCD

为解决废旧沥青混合料(RAP)和铁尾矿砂(ITS)固废处理问题,将两者充当砂石料掺加到水泥稳定碎石中,通过无侧限抗压试验、弯拉试验和温缩试验对水泥稳定碎石进行路用性能研究,分析了RAP和ITS掺量对水泥稳定碎石的影响。结果表明:RAP掺量一定时(25%),ITS掺量增加有利于提高水泥稳定碎石的抗压强度和弯拉强度,但会增大材料的温缩应变和温缩系数,降低温缩性能,其中ITS45(ITS掺量为45%)有较好的温缩性能;ITS掺量一定时(60%),RAP掺量增加不利于水泥稳定碎石的抗压强度,但可以提高水泥稳定碎石的弯拉强度,降低温缩应变和温缩系数,其中RAP70(RAP掺量为70%)温缩性能达到最优;与ITS45相比,RAP70有更宽泛的施工温度区间。     

人工神经网络在南海近海面气温反演中的应用研究

基于人工神经网络方法,利用海面水温、海面风速以及海面气压反演南海近海面气温,采用的基础数据集是国际综合海洋-大气数据集(International Comprehensive Ocean-Atmosphere Data Set,2.4 Release,ICOADS2.4)1981—2008年的观测资料,其中1981—2000年的观测资料用来建立模型,2001—2008年的观测资料用来进行模型检验。采用的人工神经网络方法是引入动量因子并采用批处理梯度下降法的BP(Back propagation)算法。试验结果表明,基于人工神经网络建立的近海面气温反演方法明显优于多元线性回归方法,尤其是在春季和冬季,海面水温、海面风速以及海面气压与近海面气温之间存在较强的非线性关系,人工神经网络的优势更加明显。总体而言,人工神经网络在各月的反演效果较均衡,均方根误差介于1.5—1.8℃之间,平均绝对误差为1.1—1.3℃。