用19.35 GHz星载微波辐射计(SSM/I)亮温反演海面风速

我们发展了一种用19．35GHz星载微波辐射计(SSM／I)亮温反演海面风速的模式，并利用同步的卫星亮温和海面浮标数据反演出海面风速，并且和浮标风速进行比较。为了说明反演算法的可用性，我们分别与目前国际上的通用反演算法的反演结果进行了比较。文章提供了一种新的、用单一波段亮温反演海面风速的方法。     

台湾海峡海表面温度的遥感反演及精度检验

海表面温度(SST)是海洋-大气系统中一个十分关键的物理量。SST为海洋学课题的研究提供了一种直观的指示量[1],在海洋捕捞中SST是寻找中心渔场的指标之一,可为渔业部门提供鱼类的回游路线和渔场的位置信息[2]。SST制约着海面和大气的热量、动量和水汽交换,是研究大气环流和气候变化[3]甚至台风移动路径[4]等气象学课题的一个重要因子。因此,SST在海洋学和气象学研究中占有非常重要的地位,此外SST对海洋运输、海洋污染、海上油气资源开发、海滨核电站建设等方面的影响近年来也倍受关注。     

利用专题微波辐射成像仪(SSM/I)检测东南极陆面亮温变化

介绍了微波辐射测量面目标表面亮度温度的原理,分析了冰雪的微波辐射特性与亮温特征。利用专题微波成像仪 (SSM/I) 数据研究了 1988 年 1－8 月份东南极内陆冰雪表面亮温变化。首先根据 37 GHz 水平极化辐射亮温 175 oK 等温线推算南极大陆冰外缘线,然后利用 37 GHz 数据计算分析了东南极内陆 1988 年年内 1－8 月的地面亮温均变化。结果表明在东南极内陆的地面亮温年内月均变化不大;在东南极的边缘,其受大洋季候风变化影响发生很大的变化。     

基于Skyline的海洋地质三维可视化系统开发与实现

融合海洋地质专题信息与海洋基础数据、遥感数据等,采用B/S架构实现基于Skyline的海洋地质Web三维GIS系统的组织、发布和应用技术,为海洋地质三维地理信息系统的实现奠定了基础,并从三维场景建模、B/S架构Web可视化和系统功能设计等方面详细地介绍了Skyline软件在海洋地质GIS中的集成应用。     

基于雷达高度计增益自动控制数据的风速反演算法研究

基于Jason-1卫星雷达高度计与NDBC(National Data Buoy Center)浮标的时空匹配数据集,利用BP(Back Propagation)神经网络方法建立了基于后向散射系数σ₀与有效波高(Significant Wave Height,SWH,)的双参数(σ₀-H_sw)风速反演模型,并探讨利用AGC(Automatic Gain Control)来代替σ₀对风速反演的可行性进行研究。结果表明,所建立的σ₀-SWH风速反演均方根优于0.3 m/s(风速范围为0.5~20 m/s); AGC-SWH模型反演精度偏低(1.3 m/s),但在星星交叉定标的基础上,模型精度提高了0.9 m/s。这个研究工作尤其是交叉定标基础上的AGC-SWH模型反演流程对"HY-2"海面风速反演有一定的借鉴意义。     

基于D-S理论的卫星遥感海表面温度和同化数据融合方法

利用卫星遥感获取海表面温度实时性强,但其数据质量随大气环境而波动;利用同化技术求解的海表面温度局部精度高,但覆盖面与实时性差.鉴于两种技术适应不同情况,拟使用信息融合技术实现两者优势互补,即根据各自的优势和局限性对数据点进行一致性评价和加权融合计算,在提高精度的同时对结果的不确定性进行量化和评价.以我国东部海域海表温度为例的采样试验结果表明,融合法更适应复杂的环境.     

基于BP人工神经网络的水体遥感测深方法研究

利用Landsat7 ETM 遥感图像反射率和实测水深值之间的相关性,建立了动量BP人工神经网络水深反演模型,并对长江口南港河段水深进行了反演。结果表明:具有较强非线性映射能力的动量BP神经网络模型能较好地反演出长江口南港河段的水深分布情况;由于受长江口水体高含沙量的影响,模型对小于5m的水深值反演精度较高,而对大于10m的水深值反演精度较低。     

基于OpenSceneGraph 的海洋环境三维可视化系统研究

为了研究虚拟现实技术在海洋环境三维可视化中的应用,对大气、海底地形、风浪流等数据产品进行了分析整理,运用场景裁剪、level of details(LOD)细节层次、场景动态调度等关键技术方法,结合Visual Planet Builder(VPB)、ARCGIS多种数据处理工具,在VC++和OSG2.8.7的可视化开发环境上,构建了一个三维、动态、实时、可交互的海洋环境可视化模拟仿真系统。这个系统可以为海洋科学研究和工程建设提供一个更加便捷、直观的可视化平台。     

支持海洋遥感信息提取技术的可视化建模系统流程设计

根据海洋遥感信息提取可视化建模应用需求,以用户可视化模型建立及流程设计实现为目标,采用统一建模语言UML面向对象分析方法,设计海洋遥感信息提取可视化建模系统软件结构、用户需求用例(use case)结构、类(class)结构及流程图表示法,同时完成流程定义器、流程调度的设计和实现.结果表明,可视化用户建模系统可以使广大海洋用户在使用遥感数据时无须在数据预处理及转换工作上花费较多的时间,也不要学习很多遥感信息处理专业知识即可适应和使用组件式海洋遥感数据处理和信息提取通用软件,并且在该软件平台上进行他们的研究和应用开发工作.     

基于水深分段选择因子的多光谱影像反演水深

岛礁周边海底地形精密测量是海洋测绘的难点问题之一,利用多光谱卫星能精确测定岛礁周边水深地形,是传统岛礁水深测量有效的补充方式之一。本文以蜈支洲岛周围水域为研究区域,提出了基于BP神经网络水深分段选取反演因子的方法,利用WorldView-2数据和多波束实测数据建立多模型,整合预测的各段水深获得海底地形。实验表明,本文方法能充分利用水体的光谱特性,与单一BP神经网络模型结果相比,MRE降低了6.4%,RMSE降低了1.2 m,是一种可行的多光谱水深反演的方法     

星载SSM/Ⅰ微波遥感渤海海冰的辐射特征分析

根据我国渤海区域星载微波遥感DMSPSSM/I1994～1996年的观察数据的研究,指出现有的星载微波遥感海冰的数据标定和验证TBI和OSI算法是不适用的.用22和85GHz的散射指数SI和19GHz的极化指数PI,讨论了渤海区域海冰的主要辐射特征,用矢量辐射传输理论数值模拟了SI、PI与海冰覆盖及其厚度变化的定量关系,用SI-PI图规划了渤海区域性海冰的识别方法,给出了渤海海冰的空间分布及其辐射特征的时间序列变化.     

Monitoring regional sea ice of the Bohai Sea by SSM/I scattering index

SSM/I data on the Bohai Sea of China from 1994 to 1996 have been studied.The sea ice algorithms of calibration/validation such as the brightness temperature index [AES/YORK TBI (Hollinger et al.,1992)] and ocean scattering index [OSI (Ferraro et al.,1996, The Bulletin of the American Meteorological Society, 77(5), 891-905)] are not applicable to the detection of regional sea ice of mid-latitude Bohai area.This paper presents a method of the scatfeting index SI and polarization index PI to identify regional Bohai Sea ice.Numerical results of vector radiative transfer for a model of a layer of sea ice over ocean simulate the relationship between SI/PI and sea ice depth, and others.It is employed to categorize the SI/PI indexes for the detection of sea ice.     

Monitoring regional sea ice of the Bohai Sea by SSM/I scattering index

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A GPS and Cold Ocean Brightness Temperature Calibration of the ERS-2 and TOPEX/Poseidon Microwave Radiometers

Sea-level change studies from altimetric satellites are reliant on range stability of the sea surface heights computed from orbital positioning and geophysically corrected data. One such correction, namely the wet tropospheric delay induced by the highly variable atmospheric water vapor content, is provided by radiometers onboard ERS-2 and TOPEX/Poseidon (T/P). In this study the long-term stability of the ERS-2 microwave radiometer (E2MR) and the T/P microwave radiometer (TMR) are investigated with the observed drift in the brightness temperatures approximated by reference to the coldest temperatures over the oceans. The E2MR stability is characterized by a gain anomaly fall in 1996 and a drift in the 23.8 GHz channel. For the TMR, investigations show that the dominant drift is about 0.2 K/year in the 18 GHz channel over the first 7-8 years but stabilizing and even decreasing slightly thereafter. In contrast, the 21 GHz and 37 GHz channels are comparatively stable. Utilizing correction formulae a modified wet tropospheric range is inferred from “small-change” analysis of the radiometric correction given on the altimetric Geophysical Data Records. The accuracy of this formulism is validated by independent comparison against GPS derived wet tropospheric delays inferred at 14 coastal IGS stations with near continuous data from September 1992 through to the present day. Comparisons between GPS results for ERS-2 and T/P show that the E2MR path delay is 14 mm short. For T/P, the spatial distribution of the wet tropospheric enhancement is further investigated to show that the nonuniformity can equate to a deviation in sea-level height change of about 0.1 mm/year compared with global average sea-level change. Finally, the altimetric range stability of T/P is revisited by comparison against time series from the global network of tide gauges. Analysis shows that the validated TMR drift correction results in a residual trend of -0.27 ± 0.11 mm/yr which is not significant at the 3σ level.     

On the Development of Models for Height Profiles of the Wind Speed in the Atmospheric Surface Layer

The reliability of the known models of a height profile of the wind speed V(h) in the atmospheric boundary layer (ABL) and near-surface layer (NSL) is analyzed using the data of long-term ABL measurements accumulated in Russia in the state network of meteorological and aerological stations and the data of multilevel measurements at mast wind-measuring complexes. A new multilayer semiempirical model of V(h) is proposed which is based on aerodynamic and physical representations of the ABL vertical structure and relies on the hypothesis that wind-speed profiles providing the minimum wind friction on the ground and satisfying the conditions of profile smoothness are feasible in the ABL. This model ensures the best agreement with the data of meteorological, aerological, and mast wind measurements.     

埕岛油田潮流、风海流预报系统的研制与应用

在埕岛油田潮流、风海流预报系统中应用了整体潮流预报法,结合对本海域潮流实测资料,研究编制成操作简便、功能强大的潮流预报应用软件,实现了对埕岛海域潮流和风海流的即时预报,用于指导油田生产管理,并取得了较好的效果。     

海底可视技术在大洋科考中的应用和发展趋势

海底可视技术是一种直观地进行海底调查的手段,在大洋科考调查中发挥着重要的作用。文中介绍了海底摄像、电视抓斗和无人缆控潜水器(ROV)等海底可视设备在大洋科考中的应用情况,并提出了自治水下机器人(AUV)在大洋科考中的应用趋势。     

Assessment of the Jason Microwave Radiometer's Measurement of Wet Tropospheric Path Delay Using Comparisons to SSM/I and TMI

The Jason microwave radiometer (JMR) provides a crucial correction due to water vapor in the troposphere, and a much smaller correction due to liquid water, to the travel time of the Jason-1 altimeter radar pulse. An error of any size in the radiometer's measurement of wet path delay translates as an error of equal size in the measurement of sea surface height, the ultimate quantity that the altimetric system should yield. The estimate of globally-averaged sea surface height change associated with climate change, requires that uncertainties in the trends in such a global average be accurate to much better than the signal of 1–2 mm/yr. We first compare the JMR observations to those from the TOPEX/Poseidon radiometer (TMR) over approximately six months, since the intent of Jason is to continue the 10-year time series of precision ocean surface topography initiated by T/P. We then assess the stability of the JMR measurement by comparing its wet path delay to those of other orbiting radiometers over 22 months, specifically the Special Sensor Microwave Imager aboard the Defense Meteorological Satellite Program (DMSP-SSM/I) series of satellites, and the Tropical Rainfall Mapping Mission's Microwave Imager (TMI), as well as the European Center for Medium Range Weather Forecasting's (ECMWF) atmospheric numerical model estimate of water vapor. From the combined set, we obtain a robust assessment of the stability of JMR measurements. We find, that JMR is in remarkable agreement with TMR, only 2.5 mm longer, and 6–7 mm standard deviation on their difference in 0.5 degree averages; that JMR has experienced a globally-averaged step-function change, yielding an apparent shortening in wet path delay estimates of 4–5 mm around October 2002 (Jason cycles 28–32); that this step-function is visible only in the 23.8 GHz channel; and that the 34 GHz channel appears to drift at a rate of ?0.4K/year. In addition, we find that, while in 2002 there was no evidence of sensitivity to the Jason satellite's attitude (a correlation of the wet path delay with yaw state), in 2003 there are strong (2–3 mm, up to 7 mm globally averaged) changes associated with such yaw state. These JMR issues were all found in the first 22 months of Jason's geophysical data records (GDR) data, and thus they apply to any investigations that use such data without further corrections.