一种改进的近红外波段悬浮物生物光学反演模型

在分析固有光学参数和表观光学参数之间关系的基础上,提出一种提高悬浮物浓度的反演精度的算法。本文算法细化单位散射系数曲线的斜率s’值,并将bbp（λ）×bρ（λ）视为一个一定数值范围内的变量,其中b’bp（λ）为波长A处的悬浮物后向散射概率,bρ（λ）为悬浮物的单位散射系数。以太湖为实验区,进行了水体野外实测,获得了遥感反射率、吸收散射系数、后向散射系数、悬浮物浓度等必要参数。利用本文改进算法反演悬浮物浓度的平均相对误差绝对值为22．58％,均方根误差为13．12mg／L,均小于已有研究中将涉及的相关参数看做单一定值时,取得的平均绝对误差（44．78％）和均方根误差（31．57mg／L）。     

Optical properties of estuarine dissolved organic matter isolated using cross-flow ultrafiltration

Dissolved organic matter(DOM) from freshwater, mid-salinity, and seawater endmember samples in the Jiulong River Estuary, China were fractionated using cross-flow ultrafiltration with a 10-kDa membrane. The colloidal organic matter(COM; 10 kDa–0.22 μm) retentate, low molecular weight(LMW) DOM(10 kDa) permeate, and bulk samples were analyzed using absorption spectroscopy and three-dimensional fluorescence excitation-emission-matrix spectroscopy. The UV-visible spectra of COM were very similar to those obtained for permeate and bulk samples, decreasing monotonically with increasing wavelength. Most of the chromophoric DOM(CDOM, expressed as the absorption coefficient a355) occurred in the LMW fraction, while the percentage of CDOM in the colloidal fraction was substantially higher in the freshwater endmember(13.4% of the total) than in the seawater endmember(6.8%). The bulk CDOM showed a conservative mixing behavior in the estuary, while there was removal of the COM fraction and a concurrent addition of the permeate fraction in the mid-salinity sample, implying that part of the colloidal CDOM was transformed into LMW CDOM. Two humic-like components(C1: 250, 325/402 nm; and C2: 265, 360/458 nm) and one protein-like component(C3: 275/334 nm) were identified using parallel factor analysis. The contributions of the C1, C2, and C3 components of the COM fraction to the bulk sample were 2.5%–8.7%, 4.8%–12.6%, and 7.4%–14.7%, respectively, revealing that fluorescent DOM occurred mainly in the LMW fraction in the Jiulong River Estuary. The C1 and C2 components in the retentate and permeate samples showed conservative mixing behavior, but the intensity ratio of C2/C1 was higher in the retentate than in the permeate fractions for all salinity samples, showing that the humic component was more enriched in the COM than the fulvic component. The intensity ratio of C3/(C1+C2) was much higher in the retentate than in the permeate fraction for mid-salinity and seawater samples, revealing that the protein-like component was relatively more enriched in COM than the humic-like component. The contribution of the protein-like component(C3) to the total fluorescence in the retentate increased from 14% in the freshwater endmember to 72% for the seawater endmember samples, clearly indicating the variation of dominance by the humic-like component compared to the protein-like component during the estuarine mixing process of COM.     

浅水FPSO限位作业系泊分析

以浅水单点系泊装置水下软钢臂维修解脱为背景,研究在拖轮限位状态下FPSO运动与限位缆绳张力。计算在不同水深及浪向条件下,FPSO的二阶传递函数(QTF);分别应用Newman近似方法、全QTF法以及使用部分QTF值的方法,计算FPSO时域低频波浪载荷,并对其限位响应进行对比;计算不同长度时的限位缆绳张力响应,分析限位缆绳长度及FPSO波频运动对缆绳张力的影响。分析表明:Newman近似的适用性,应根据FPSO的QTF与海浪谱能量集中范围综合判断;为减少QTF计算量,可根据FPSO低频运动固有频率,确定频率间隔△ω的计算上限,采用部分QTF值计算低频波浪载荷,其响应预报结果与全QTF法接近;若FPSO的RAO能够避开海浪谱能量集中的频率范围,则在限位分析中可忽略FPSO波频运动的影响。     

浅海新型FPSO-IQFP多点系泊系统设计研究

海上油气生产要求FPSO具有低幅运动的特性,因此系泊系统性能的优劣直接影响生产作业的效率和安全。针对新概念FPSO-IQFP(圆角倒棱台形FPSO)的浮体特点和边际油田经济性开发的需要,设计一套经济有效的多点系泊系统。首先,将钢制悬链线系泊系统和聚酯纤维张紧式系泊系统作为备选方案,根据定常力计算结果并参照工程经验,给出两种系泊系统的初始设计方案,并进行二者的静特性分析,探讨系泊参数对系泊系统受力和位移的影响规律;在此基础上,结合时域计算结果,确定系泊系统的优化设计方案;最后,给出系泊系统的回复力和浮体位移之间的关系曲线,并在静力范围内比较两种系泊系统的优劣性。静力分析结果初步验证,较之悬链线系泊系统,张紧式系泊系统用于浅水作业的IQFP上更具优越性。     

Spike in phytoplankton biomass in Greenland Sea during 2009 and the correlations among chlorophyll-a,aerosol optical depth and ice cover

The distributions and correlations of chlorophyll-a(Chl-a),aerosol optical depth(AOD)and ice cover in the southeast Arctic Ocean-Greenland Sea(10°W–10°E,70°–80°N)between 2003 and 2009 were studied using satellite data and statistical analyses.Regression analysis showed correlations between Chl-a and AOD,Chl-a and ice cover,and AOD and ice cover with different time lags.The time lag of Chl-a and AOD indicated their long-term equilibrium relationship.Peaks in AOD and Chl-a and generally occurred in May and July,respectively.Despite the time lag,the correlation between Chl-a and AOD in the study region was as high as 0.7.The peak gap between Chl-a and AOD shifted for about 6 weeks during 2003–2009.In the summer and autumn of 2009,Chl-a and AOD levels were much higher than during the other years,especially in the northern band of the study region(75°–80°N).The driving forces for this localized increase in phytoplankton biomass could be mainly attributed to the very high rate of ice melting in spring and early summer and the high wind speed in autumn,together with the increased deposition of aerosol throughout the year.The unusually high AOD in the spring of 2003 was mainly due to a massive fi re in Russia,which occurred in the fi rst half of the year.Over the 7 years of the study,the sea surface temperature generally decreased.This may have been due to the release of dimethylsulfi de into the air,excreted in large amounts from abundant phytoplankton biomass,and its subsequent reaction,form large amounts of aerosol,and resulting in regional cooling.     

Characterization of Stratospheric Aerosol Distributions during the Volcanically Quiescent Period of 1998–2004

The Stratospheric Aerosol and Gas Experiment （SAGE） II aerosol extinction profiles at 1020 nm were used to study the distribution characteristics of stratospheric aerosols during the volcanically quiescent period of 1998-2004. The stratospheric aerosol distributions exhibited hemispheric asymmetry between the Northern Hemisphere （NH） and the Southern Hemisphere （SH）. In the lower stratosphere below 20 km, the zonal averaged aerosol optical depths in the NH were higher than those of the corresponding SH; whereas at higher altitudes above 20 km, the optical depths in the SH-- except the equatorial region--were higher than those of the NH. At 0-10°N and 10-20°N, the stratospheric aerosol optical depth （SAOD） exhibited larger values in boreal winter and lower values in the spring and summer; at 0-10°S and 10-20°S, the SAOD presented small seasonal variations. At 30-40°N, the SAOD presented larger values in the boreal fall and winter and lower values in the spring and summer; while at 30-40°S, the SAOD exhibited larger values in the austral winter and early spring and lower values in the summer and fall. These characteristics can mainly be attributed to the seasonal cycle of the dynamic transport, and the effects of the buildup and breakdown of the polar vortex. At 50-60°S, the SAOD exhibited extremely high values during austral winter associated with the Antarctic polar vortex boundary; at 50-60°N, the SAOD also exhibited larger values during the boreal winter, but it was much less obvious than that of its southern counterpart.     

第19届中国遥感大会征文通知

正经研究决定"第十九届中国遥感大会"将于2014年9月20-23日在西安市召开。本届大会由中国遥感委员会主办,北京空间机电研究所、中国宇航学会空间遥感专业委员会、中国遥感应用协会光学遥感专业委员会共同承办。会议旨在交流近年来国内遥感领域在理论、技术与应用等方面的最新进展,展示遥感技术最新成果。大会同期将举行第八届中国青年遥感辩论会、遥感科技创新展、中国遥感影像艺术展、遥感科普文化周等活动。     

基于TerraSAR-X影像的光学遥感影像地理定位研究综述

目前,我国遥感技术应用中最普遍采用的是通过光学遥感获取影像,这种方法一般需要控制点才能获得高分辨率遥感影像,不可避免地限制了其应用范围。然而TerraSAR-X具有精确的传感器校正、高精度的卫星位置及对卫星姿态的低依赖性等特性,在无地面信息的情况下,仍然可以获得高精度的遥感影像。因此,研究利用TerraSAR-X数据作为地面控制信息对光学遥感影像进行地理定位具有突破性的意义和价值。本文介绍了近几年TerraSAR-X影像对光学遥感影像进行定位的现状和方法,阐述了其理论基础和优缺点,并试着分析了现阶段争论的焦点。     

水体悬沙浓度连续测量技术研究综述

水体悬沙浓度是水利、环境、河口海岸与海洋相关研究领域最为基础的数据需求之一。随着传感器技术的发展, 悬沙浓度连续测量技术在悬沙浓度测量领域表现出高时空分辨率、长期数据采集的成本和风险均较低的突出优点。本文综述了光学、声学、音叉谐振、压差和放射性射线衰减等原理用于悬沙浓度连续测量技术的相关研究进展, 探讨了各技术方法的优、缺点, 并提出了今后的研发重点和发展方向主要在以下几个方面: 1) 光后向散射原理是低成本、小型化和高时频测量悬沙浓度的最优技术路线, 需着力于开展量程扩增和粒径敏感度削弱研究; 2) 低不确定度悬沙浓度垂向剖面观测的实现依赖于超声后向散射原理技术路线的发展; 3) 音叉谐振原理技术路线尤为契合高含沙水流和浮泥工况下的超高量程应用场景; 4) 多技术路线传感器融合以及使用人工智能算法模型替代正向反演模型。     

利用光学跟踪与结构光扫描相结合的高精度测量方法

结构光扫描测量是广泛应用于精密生产制造的方法之一,相对于常见测量方法具有较高的点密度、点位精度,以及非接触测量的优势。针对常规的结构光扫描测量存在的测量范围小、路点示教耗时烦琐等不足,本文提出了一种光学跟踪器与结构光扫描仪相结合的测量方法。利用光学跟踪器实时测量结构光扫描仪的空间姿态,将扫描点云实时转换至同一坐标系中,实现了大尺寸、高点密度、高精度实时测量。通过反射面型面的非接触测量试验对该方法的测量精度进行评价。试验结果表明,对于直径为3.1 m的大型反射面,扫描结果与数模的最佳拟合RMSE最小为0.067 mm,优于型面制造要求的0.15 mm精度,可满足高精度的工业生产制造精度要求。