融合卫星测高和船测重力数据的非均匀密度点质量方法

融合多源海洋重力数据是提升极地、近岸和海底地形复杂区域卫星测高反演海洋重力场模型精度的重要途径.利用国际公开的船测重力数据与测高重力场模型,以琉球群岛附近海域为例,本文分析了点质量密度和船测重力数据分布对点质量模型融合精度的影响,结合船测重力数据分布,构建了基于迭代移去恢复的非均匀密度点质量模型.在相同船测重力约束下,非均匀密度点质量模型融合精度较均匀密度的点质量模型提升可达12％.     

联合多代测高数据建立中国海域重力异常模型

本文联合T/P数据、T/P新轨道数据、ERS数据、GFO数据、GeosatGM数据和ERS-1/168数据,用测高卫星记录点的位置信息直接计算沿轨大地水准面的方向导数,结合测线轨迹方向的方位角在交叉点处推求垂线偏差,然后利用逆Vening-Meinesz公式计算了中国近海(0o～41oN,105o～132oN)2′×2′格网分辨率的海域重力异常模型。将其与CLS_SHOW99重力异常模型比较,统计结果表示与该模型差异的RMS为8.15mgal,在剔除差值大于20mgal的点(剔除3.3%)以后,RMS为4.72mgal;与某海区船测重力异常比较的RMS为8.91mgal。     

海洋重力场特征统计模型计算与分析

海洋重力场特征参数在地球重力场逼近计算和海上测量优化设计中具有重要的应用价值。基于卫星测高重力在海域具有覆盖范围广且分布均匀的独特优势,提出了利用最新卫星测高重力数据集开展海洋重力场特征统计模型计算和分析的研究方案,给出了代表误差和协方差函数模型参数的计算公式,定义并研究了海洋广义布格重力异常的变化特征,提出了等精度和非等精度拟合经验协方差函数的计算模型。利用中国近海及西太平洋海区超过50万个5'×5'方块的1'×1'网格卫星测高重力异常数据,首次计算得到一组有代表性的中国周边海域重力场特征统计模型参数,较好地揭示了海洋重力场有别于陆地重力场的变化特征,利用海面船测重力数据对计算结果进行了可靠性检核,提出了相应的模型参数修正方案和使用建议。     

联合多种测高数据确定中国边缘海及全球海域的垂线偏差

联合多种测高资料,基于EIGEN_CG01C重力场模型,采用沿轨迹加权最小二乘方法确定了中国边缘海和全球海域格网垂线偏差（IGG2006_DOV）,中国海域整体精度优于1.2″,满足了反演高分辨率、高精度海洋重力场对测高垂线偏差的精度要求。在南海海域,基于测高垂线偏差解算的重力异常与船测重力进行了外部检核,精度达到7.75 mGal。     

卫星测高误差对海洋重力场反演的影响

本文研究了卫星测高误差对海洋重力场探测的影响,导出了卫星测高随机误差在海洋重力异常推估过程中的误差传播公式,实验分析了卫星测高随机误差在多种测量分辨率下对重力异常推估值影响的大小,可为我国未来的测高卫星系统论证设计提供技术参考。     

垂线偏差-大地水准面与逆范宁-梅尼兹公式的应用——联合多种卫星测高数据求解全球海平面与海洋重力异常

卫星测高开辟了地球科学研究的新纪元。平均海面高(MSSH)和海洋重力异常是卫星测高在大地测量和地球物理应用领域的重要成果。平均海面高对于建立全球潮汐模型、海平面变化研究以及海洋测深等方面有重要意义。关于海洋重力异常的应用,Sandweel与Smith(1997)已进行了说明。根据卫星测高数据计算垂线偏差(DOV)是恢复重力异常的一个新途径。对利用改进的卫星测高数据进一步提高全球平均海面高和重力异     

卫星重力梯度数据重力异常的精度分析

针对GOCE卫星确定的地球重力场模型精度的不确定性,对比分析GOCE位模型与多个不同重力场模型确定的重力异常,并将其分别与船测重力数据、南极航空重力数据、北极重力数据以及美国和中国台湾地面重力数据比较研究。结果表明:GOCE位模型的内符合精度最高,与地面重力观测数据符合最优;与船测以及航空重力测量符合相对较差、精度较低。研究表明,在一定精度前提下,GOCE卫星确定的重力数据可用于无人区,从而提高重力观测数据的覆盖率。     

西太平洋海域卫星测高重力垂直梯度分布

从地球重力场基本理论出发,推导了重力垂直梯度计算的数值积分公式,并利用由多颗测高卫星联合反演的2'×2'海洋重力异常资料,解算了西太平洋海域重力垂直梯度.将计算所得的重力异常垂直梯度与现有资料进行比较,其差值均方根为±10.08E,表明两者精度相当.此外,还对差值大小和空间分布进行了深入分析.     

CHAMP重力卫星结果在中国海及邻近海域的初步分析

利用世界上第一个采用高低卫_卫跟踪技术的CHAMP重力卫星计划导出的全新的高精度全球长波重力场模型EIGEN_1S结果 ,根据二维高斯滤波原理 ,基于相同空域尺度对卫星重力结果和由卫星测高解算的几种版本的海洋重力异常数据进行了长波部分的分析研究。结果表明 ,在中国海及其邻近海域卫星重力数据与卫星测高解算的海洋重力异常数据之间存在明显的偏差。     

渤海湾航空重力及其在海域大地水准面精化中的应用

近海航空重力数据在陆海大地水准面统一中起着重要作用。近3年来,利用我国首套航空重力测量系统(CHAGS)完成了渤海湾地区近20万平方千米的5′×5′格网平均重力异常数据的获取。本文首先介绍了渤海湾地区航空重力测量的概况,给出航空重力测量数据的处理要点;然后,详细讨论了航空重力测量的精度评估方法,其中针对该区域的测线布设特点,提出了"重叠格网比较法"以评估格网平均重力异常的内符合精度。结果表明,对于5′的波长分辨率,交叉点重力异常不符值在抗差后的中误差约为1.5 mGal,重叠格网法获得的5′×5′格网平均重力异常的中误差约为1.6 mGal;5′×5′格网重力异常与卫星测高和船测重力的比较精度优于3.0mGal;由航空重力测量获得的1°×1°格网平均重力异常与GOCE卫星重力位模型的计算值相比较,其系统性差异小于0.5 mGal、中误差约为2.7 mGal。利用航空重力数据后,渤海湾区域大地水准面与16个GPS水准点的比较精度由EGM2008模型的约23 cm提高到约12 cm。     

阿克苏河-塔里木河水系水质污染遥感监测与评价

 采用Landsat TM数据分析了阿克苏河—塔里木河断面水质污染状况,通过波段的DN值和常规监测数据建立能反映水质状况的 污染物监测模型。结果发现,将2000年常规监测数据代入模型后,与遥感数据的结果基本吻合| 重建阿克苏河—塔里木河的连续水体 污染变化曲线,得出污染物浓度随着远离上游而增加。     

Monitoring drought dynamics in the Aravalli region (India) using different indices based on ground and remote sensing data

The hard-rock hilly Aravalli terrain of Rajasthan province of India suffers with frequent drought due to poor and delayed monsoon, abnormally high summer-temperature and insufficient water resources. In the present study, detailed analysis of meteorological and hydrological data of the Aravalli region has been carried out for the years 1984–2003. Standardised Precipitation Index (SPI) has been used to quantify the precipitation deficit. Standardised Water-Level Index (SWI) has been developed to assess ground-water recharge-deficit. Vegetative drought indices like Vegetation Condition Index (VCI) and Temperature Condition Index (TCI) and Vegetation Health Index (VHI) have been computed using NDVI values obtained from Global Vegetation Index (GVI) and thermal channel data of NOAA AVHRR satellite. Detailed analyses of spatial and temporal drought dynamics during monsoon and non-monsoon seasons have been carried out through drought index maps generated in Geographic Information Systems (GIS) environment. Analysis and interpretation of these maps reveal that negative SPI anomalies not always correspond to drought. In the Aravalli region, aquifer-stress shifts its position time to time, and in certain pockets it is more frequent. In comparison to hydrological stress, vegetative stress in the Aravalli region is found to be slower to begin but quicker to withdraw.     

Landslide risk analysis between Giri and Tons Rivers in Himachal Himalaya (India)

The area around Sataun in the Sirmur district of Himachal Pradesh, India (falling between the rivers Giri and Tons; both tributaries of the Yamuna River) was studied for landslide vulnerability on behalf of the inhabitants. The study was made using extensive remote sensing data (satellite and airborne). It is well supported by field evidence, demographic and infrastructural details and aided by Geographic Information System (GIS) based techniques. Field observations testify that slope, aspect, geology, tectonic planes, drainage, and land use all influence landslides in the region. These parameters were taken into consideration using the statistical approach of landslide hazard zonation. Using the census data of 1991, vulnerability of the populace to the landslide hazard was accessed. As most of the infrastructure in the region is concentrated around population centres, population data alone was used for vulnerability studies.     

Gravity Changes Before Large Earthquakes in China: 1998-2005

Although it is well known that coseismic gravity changes take place during an earthquake, previous research has not yielded convincing evidence demonstrating that significant gravity changes occur before large earthquakes. Furthermore, even if we suspect that gravity changes occur before large earthquakes, we have yet to demonstrate how to consistently observe these changes for useful earthquake forecast that would bring benefits to society. We analyzed ground gravity survey data obtained in 1998, 2000, 200...     

GNSS系统及其技术的发展研究

阐述了国际上卫星导航系统的总体发展,对美、俄、欧、中的四大全球系统,以及相关的区域系统和增强系统进行了简单的介绍,研究分析了GNSS系统及其技术的发展趋势,同时分析了我国Compass全球系统面临的机遇和挑战,并提出了我国未来工作的建议.     

“4D”技术及其应用

介绍“４Ｄ”（即数字地面模型、数字正射影像、数字栅格地图和数字线划地图）系列产品的生产流程、关键技术、及其在耕地保护、防灾减灾救灾和城市规划等方面的应用方法。     

Virtual Australia: its key elements – know,think, communicate

Abstract

Virtual Australia is not a well-defined or agreed concept. This discussion paper conceptualises Virtual Australia as a ‘virtual [digital] model containing and representing all non-trivial objects and their contextual environment – from blue sky to bedrock – in real world Australia’. It describes a scenario for Virtual Australia, one or two decades from now, in which the locations and conditions of non-trivial objects and their environment are updated automatically through a combination of remote sensing and wireless communication technologies in support of a ‘Supranet’. It then examines the concept of the ‘Supranet’ – a pervasive information network based largely on wireless technology linking the physical world to a virtual model in real time – and develops and discusses three principal characteristics of the Supranet: the ability to have or collect specific information (know); the ability to process information (think); and the ability to communicate that information. If, in the near future, any or all non-trivial devices are to some extent able to know, think and communicate, the potential for object autonomy will be realised.     

Toward seamless indoor-outdoor applications: Developing stakeholder-oriented location-based services

Location-Based Services (LBS),an emerging new business based on smartphone and mobile networks,are becoming more and more popular.Most of these LBSs,however,only offer non-seamless indoor/outdoor applications and simple applications without giving stakeholders the chance to play an active role.Our specific aim is to solve these issues.This paper presents concepts to solve these issues by expanding the Open Location Services Interface Standard (OpenLS) to allow seamless indoor/outdoor positioning and to extend the content of the services to include information recommended by stakeholders.     

GIS空间数据的采集误差及其分析

本文详细阐述了GIS数据采集过程中的误差来源，重点分析了通过地图、遥感和摄影测量等方式采集数据所产生的误差及其特性，分析了其对GIS数据的影响与消减方法。     

地理数据库的关系模型及其实现

本文从以图论观点分析地理实体入手,系统阐述了地理数据库关系模型的设计法和过程。作者于1984年4～9月间在微型机上设计建立了关系型地理数据库的实方验系统(RGDB)。该系统采用了本文提出的关系模型,采用了可动态扩库的子库组合结构,这种结构具有灵活性和提高空间利用率的优点。RGDB含有多种功能的数据操作命令,除了具有一般检索功能外,还能进行“开窗”选取和十分“自由”的映象选取。本文对RGDB系统的主要性能和实现途径作了扼要介绍。