利用选权拟合法进行GPS水汽层析解算

附加约束条件的层析解算方法是克服GPS水汽层析观测方程不适定性的主要方法,为了避免该方法中水平约束方程权阵的选取不当对水汽层析结果产生的不良影响,将选权拟合法应用到对流层水汽参数反演中。首先利用水汽参数在空间的分布规律构建参数权矩阵,并利用L曲线法确定正则化参数,然后利用模拟实验对该方法在水汽层析解算中的应用进行了验证。结果表明,该方法可以有效地克服观测方程的不适定性,反演得到符合客观实际的结果。     

降水云中液水含量的空基遥感

在建立不同降水云垂直结构模式的基础上，利用矢量微波辐射传扬模式进行空基云雨遥感的数值试验。结果表明：星载微波辐射计6．9GHz通道对降水云的冰层很不敏感，而对降水云校总液水含量(LWC)非常敏感；辐射亮温(Tb)随LWC呈单调变化关系；进一步考查这个频率下b的两个极化分量差△Tb(＝Tbv—Tbh)和LWC的关系发现，不同云结构(对流云和层状云)对△Tb-LWC关系影响较小。研究分析表明，6．9GHz的v,h两个通道有可能用于遥感降水云的液水总量。     

基于Silverlight的水行政移动执法系统设计与实现

针对当前水行政执法管理的需求及系统现状,以面向对象的设计方法,恪守＂高内聚、紧耦合＂的设计原则,采用组件化、参数化、模式化、集成化等先进构造思想,充分利用Silverlight、WebGIS、工作流、数据库、规则库、物联网、GPS等技术,采用成熟的组件和模块,构建灵活、健壮、高效、稳定的水行政移动执法系统,为提升水行政执法效率和质量提供了有力的技术和平台支撑。     

基于GIS技术的我国大气可降水量分布研究

利用分布于全国范围内的125个气象探空测站点(每日8:00和20:00)的探空数据,应用数据库编程与GIS技术,对大气可降水量在全国的分布情况进行了分析,得到了2002年全年以及春夏秋冬4个季节(2001年12月和2002年1,2月作为冬季)的平均大气可降水量在全国的分布状况。对数据进行分析可知:在空间上,我国的大气可降水量总体呈东南多,西北及青藏高原地区少的分布状况。同时,由于地形组合状况的特殊性,导致四川盆地、天山北麓等地区的大气可降水量略高于其周围地区;在时间上,夏季的大气可降水量值较高,可达到62mm左右,冬季较少,而春秋季除局部地区外大气可降水量基本持平。     

浅谈哈尔滨市群力新区地理信息系统建设

基于我院承担的"哈尔滨市群力新区地理信息系统"建设项目,从"创新"的角度简要介绍了系统建设框架、数据组织以及系统建设重点等内容。     

Water resource applications with RADARSAT-2 – a preview

Abstract

Fresh water is arguably the most vital resource for many aspects of a healthy and stable environment. Monitoring the extent of surface water enables resource managers to detect perturbations and long term trends in water availability, and set consumption guidelines accordingly. Potential end-users of water-related observations are numerous and reflect society as a whole. They encompass scientists and managers at all levels of government, aboriginal groups, water/power utility managers, farmers, planners, engineers, hydrologists, medical researchers, climate scientists, recreation enthusiasts, public school to post-graduate students, many special interest groups and the general public. Water data and analyses generate information products that benefit water resources planning and management, engineering design, plant operations, navigation activities, health research, water quality assessments and ecosystem management. As well, they serve as inputs for flood and drought warnings and weather and climate prediction models. Radar data in general, and RADARSAT in particular, are very good for detecting open surface water and have been used operationally for flood monitoring in many countries. Significant radar data archives now exist to analyse seasonal, annual and decadal trends, in order to attain a better understanding of the freshwater cycle. Radar data are also useful for wetland classification and soil moisture estimation. With the increasing pressure on water resources, both from a quality as well as a quantity perspective, the need will continue to increase for reliable information.

RADARSAT-2 has several innovations that will enhance the ability to provide useful information about water resources. This paper provides an overview of the use of radar in general, and RADARSAT-2 in particular, for the generation of information products useful to water resource managers.     

Using a simulation analysis to evaluate the impact of crop mapping error on crop area estimation from stratified sampling

ABSTRACT

To analyze the efficiency of area estimations (i.e. estimation accuracy and variation of estimation) impacted by crop mapping error, we simulated error at eight levels for thematic maps using a stratified sampling estimation methodology. The results show that the estimation efficiency is influenced by the combination of the sample size and the error level. Evaluating the trade-offs between sample size and error level showed that reducing the crop mapping error level provides the most benefit (i.e. higher estimation efficiency). Further, sampling performance differed based on the heterogeneity of the crop area. The results demonstrated that the influence of increasing the error level on estimation efficiency is more detrimental in heterogeneous areas than in homogeneous ones. Therefore, to obtain higher estimation efficiency, a larger sample size and lower error level or both are needed, especially in heterogeneous areas. We suggest that existing land-cover maps should first be used to determine the heterogeneity of the area. The appropriate sample size for these areas then can be determined according to all three factors: heterogeneity, expected estimation efficiency, and sampling budget. Overall, extending our understanding of the impacts of crop mapping error is necessary for decision making to improve our ability to effectively estimate crop area.     

一种改进的快速最小高差DEM匹配方法

利用最小高差(LZD)法进行DEM匹配时,当待匹配DEM的分辨率比参考DEM高时,确定的同名点中存在冗余,将导致计算冗余和效率降低。为解决上述问题,对LZD法确定同名点的模型进行改化,提出一种改进的基于最小高差原理的快速DEM匹配方法。该方法根据参考DEM的格网点确定同名点以避免冗余,并通过近似确定同名点及其高差,有效简化了计算过程。实验结果表明,该方法在保证较高的收敛速度和匹配精度的基础上,可有效提高计算效率,且计算效率不随待匹配DEM分辨率提高而降低,DEM间分辨率差异越大,方法的优势越明显。     

双差精密定轨中地面站的选取方法

针对目前全球的地面测站数量多、测站观测数据质量参差不齐及测站地理分布不均的问题,总结了一种测站选取方法。利用该方法编制的测站选取软件对IGS站进行了选择,并根据选得的测站设计了几种定轨试验。结果显示,利用由本文的测站选取方法得到的70个基准站进行定轨时,得到的卫星位置与IGS精密星历在径向、切向、法向偏差均方根分别为1.11、2.19、1.72cm。验证了本文选站软件的可靠性,避免了选站过程中过多的人为因素,并且在保障精度的前提下提高了定轨效率。     

丹江口水库面积季节变化遥感监测

基于2014年2月19日、2014年6月7日和2014年10月8日的三景资源三号卫星影像分别作为春季、夏季和秋季的代表,以河南省内的丹江口水库为研究区域,采用面向对象的遥感影像监督分类方法进行影像的分割和分类,提取出遥感影像中的水体,并结合南水北调中线工程对水域面积和周围地物的影响对这3个时期的影像进行比较和分析,得出这3个时期水域面积的变化数据。