NOTICE OF THE EDITORIAL DEPARTMENT

The "Special Issue of Seminar on the Wang Zhizhuo's Academic Thinking" (Chineseand English Editions) edited by the editorial department of "ACTA GEODETICA etCARTOGRAPHICA SINICA" of Chinese Society of Geodesy. Photogrammetry and Car-tography in collaboration with that of the Journal of Wuhan Technical University of Sur-veying and Mapping has been published and is put on sale.     

Pinpointing Source of Mekong and Measuring Its Length Through Analysis of Satellite Imagery and Field Investigations

For centuries, explorers and scientists from different countries had made their own conclusions on the source of the Mekong. However, the geographic source of the Mekong is still arguable because of the complexity of the Mekong source water system, inaccessible environment and the varied technologies used by those explorers and scientists. The satellite remote sensing technology has been used to pinpoint the source of the Mekong, associated with the on-the-spot investigations made by the authors in June 1999 and September 2002. The actual length of the Mekong has also been calculated.     

Self-calibration Applied in Converting Simulation Surveying

In the field of converting simulation surveying and traditional close range photogrammetry, it has been developed so far to survey objects by commercial digital camera and this technique is applied widely in every part of production. In order to get three-dimensional information of objects, commercial digital camera must be examined. For a long time, digital camera has been examined by DLT. Then there must be a high-precision control field. For realizing surveying without control points, a method for self-calibration is proposed.     

中国地图学的进一步发展

During the period of the seventh "Five—Year Plan" economic construction in China, the cartographic undertaking has been playing an increasing role in he economic and social development of the country, which in turn further promotes the advancement of this discipline.     

A Method for Generating Contour Tree Based on Voronoi Interior Adjacency

IntroductionTopographic contour lines play an i mportantrole in the process of humans analyzing land-form. Particularly ,the spatial relations of con-tours are usually analyzed andinterpreted by hu-mans to recognize topographic features .In orderto model and represent the relationships betweencontour lines ,in 1963 Boyell and Reston pro-posed a contour tree generated by mapping con-tour lines as edges and interstitial spaces asnodes[1 ,2].There has been a great deal of previous workrepresenti…     

Interrelations between socio-economic development and environmental quality: a simulation integrating system dynamics models with GIS

System dynamics （SD） theory has long been deployed in modeling complex non-linear interrelationships but, so far it has not been common to do the kind of modeling in support of bringing environmental sustainability policies to practice. This is largely because the challenge of including spatial data has not yet been well met. Potential for adoption of SD and GIS methods in combination is exemplified with the results of a decision-support exercise designed for simulation and prediction of the dynamic inter-relationships between socio-economic development and environmental quality for the “Wen, Pi, Du” county in Sichuan province, southwestern China.     

用气象卫星数据对冬小麦进行估产的试验

The NOAA is a special meteorological satellite. The first and second channels of the AVHRP (the sensor of NOAA) are much similar to the fifth and seventh channels of the resource satellite MSS, and their corresponding spectral response curves are much alike. The AVHRR'S first channel has a higher reflectivity from soil, and the second channel is highly reflected by vegetation. By virtue of its wide sensitivity range, multiple reception orbitals, economical and convenient, it has been used in the W.S.A. in the agricultural estimation.According to the characteristic spectra from the vegetation, and through the digital exchange of the measuraed values on the first and second channels of the NOAA/AVHRR, We established a servies of green models which can be need in making agricultural estimation satisfactorily.As expesimentally showed that these green models highly correlated to the yeild of crops. This has been presently becoming the main information sources for yield estiraatings. With the forecast of the     

APPLICATION OF SEPARABILITY CRITERION IN DESIGN OF DEFORMATION MONITORING NETWORKS

A monitoring scheme must be so designed that several possible mod-els can be efficiently separated in the stage of analysis of deformation measure-ments.Based on the concept of separability developed by Chen and Chrzanowski,a methodology for the design of monitoring schemes has been developed by the au-thors.In the method a computer simulation technique is employed,into whichsome rules have been elaborated allowing minimal human intervention.In this pa-per the criterion is first presented and the design technique using the step one up-dating procedure is discussed.Finally,design of a simulated monitoring networkis made as a demonstrating example.     

海冰微波辐射传输模式和实验研究

海冰是影响地球热循环的重要因素。以海冰和海水的微波热辐射为源,并通过位于海面遥感海冰的３层分层介质系统的分析,取得中间介质厚度与所接收到的辐射亮温有如下模式：ＴＢ＝Ａ＋Ｂｅ－ＣＤ。其中Ａ,Ｂ,Ｃ与遥感系统的极化,使用角度和角频率有关,可以通过实际地面的海冰测试试验获得。该模式符合电磁场在有损介质中的传播特性,反映出被动微波遥感所接收到的能量与传播距离的关系。近几年来,根据该模式,使用４个频段微波辐射计在地面进行实测（入射角为０°）,在飞行中使用３个频段,结果空中和地面基本符合。实践证明其模式是正确的可行的。文中给出在辽东湾测得航线上的冰厚度分布和亮度温度与冰厚度的统计曲线。最后指出影响测量并限制对厚度识别的几种因素。     

海冰微波辐射的数值模式和遥感实验测量

本文用多频段微波辐射计(1.4,3.09,5.4,36 GHz)对辽东湾和渤海湾的海冰热辐射进行了遥感测量。海冰模拟为一层介电强起伏的各向异性的随机介质。求解随机介质的辐射传输方程,得到海冰的辐射亮度温度。数值计算的结果与实验数据进行了比较,并对辐射亮度温度和海冰各种参数之间的函数关系进行了讨论。     

NASA MODIS海冰产品评价分析——以辽东湾海冰监测为例

NASA开发的MODIS海冰产品可提供全球范围的海冰分布和冰表温度信息,但将其直接用于局地和区域海冰监测时,其精度还有待进一步验证.以辽东湾冬季海冰监测为例,对MODIS海冰产品进行了分析,发现该产品将区域内绝大部分海冰标识为云.根据NASA的海冰算法,利用反射率和冰表温度(Ice Surface Temperatur...     

Observation of Sea-Ice Thickness Using ENVISAT Data From LÜtzow-Holm Bay, East Antarctica

To investigate the suitability of synthetic aperture radar (SAR) polarization data to estimate the sea-ice thickness in early summer in Lutzow-Holm Bay, Antarctica, we compared in situ ice thicknesses with the corresponding backscattering co-efficient for each polarization and the VV-to-HH backscattering ratio. The VV-to-HH backscattering ratio was derived from data acquired by ENVISAT Advanced SAR (ASAR). This ratio is related to the near-surface dielectric constant of the sea ice, which is, in turn, related to the developing process of ice and, thus, its thickness via changes in the near-surface sea-ice salinity. The sea ice encountered in the study area is close first-year pack ice and fast ice. For these old and relatively rough sea-ice types, the VV-to-HH backscattering ratio can be expected to depend on salinity-driven changes in the near-surface dielectric constant rather than changes of the surface roughness. We applied the empirical relationships between the ice thickness and the VV-to-HH backscattering ratio with the linear and logarithm fits to ASAR data. The linear fit gave the reliable result, with an rms error being 0.08 m and a correlation coefficient being 0.91, when compared to in situ fast-ice thickness.     

基于卫星测高后向散射系数的极区海冰分布特性研究

海冰对气候变化非常敏感,了解极地海冰分布范围和表面属性不仅对于极地环境非常重要,对全球温度趋势估计和建立全球气候模型非常关键。ENVISAT卫星可覆盖至南北纬81.4°,其携带的RA2雷达高度计为极地海冰研究提供了周期性的主动微波海冰探测途径。本文用ENVISAT雷达高度计探测的Ku波段后向散射系数对2011年南极和北极各月份的海冰覆盖特征（范围和海冰表面属性）进行了详细研究,利用海水和海冰的不同散射特征,设置后向散射系数阈值为13db可成功分离海冰和海水。除夏季外,雷达高度计和美国冰雪数据中心基于辐射计获取的极区海冰覆盖边界高度符合。因北极中央区域（81.4°N以北）没有轨迹覆盖,本文只估计了南极海冰的覆盖面积,夏季海冰的覆盖范围面积比辐射计探测结果偏大,这和雷达高度计对离散薄冰较强的观测能力关,在海冰密集分布的其他季节结果则有很好的符合,其中冬季面积平均差异为0.17 Mkm2。分析了南极和北极海冰的分布特征差异,和南极相比北极冬季海冰表面较粗糙干燥,而夏季海冰表面湿度较大。本文研究结果表明ENVISAT雷达高度计可准确的探测包括海冰覆盖和海冰表面属性变化在内的海冰季节性演变过程,可在海冰监测、极地科考等领域中发挥重要作用。     

GNSS-R信噪比信号在海面测高技术的研究综述

自全球卫星导航反射信号(GNSS-R)概念提出以来,GNSS-R被广泛应用于遥感方面. 如海面测高,海面风场反演,海冰检测等多个方面. 文中主要介绍了GNSS-R遥感技术在海面测高的应用和研究进展,着重介绍了基于信噪比(SNR)数据测量方法的研究进展,简述了SNR数据测量方法所涉及的理论和信号处理的办法,并根据现有的研究进展,对未来海面测高的发展方向进行展望.      

基于CryoSat-2数据的海冰厚度估算算法比较

以北极为研究区,使用CryoSat-2数据,利用现有海冰厚度卫星测高研究中4种主流算法(Laxon03算法、Kurtz09算法、Yi11算法和Laxon13算法)分别对北冰洋海冰厚度进行估算,并将估算结果与研究区IceBridge机载激光测高冰厚数据进行了比较,探索各算法海冰厚度估算的差异,寻找最优的估算算法,为估算长时序海冰厚度提供基础和参考。结果表明,4种算法估算的海冰厚度空间分布较为一致,但不同算法估算的结果差异较大,可达0.476 m;4种算法估算结果大小依次为Laxon03算法、Yi11算法、Laxon13算法、Kurtz09算法;4种算法估算的平均海冰厚度差异,在北极波弗特海海域最大,其次是北极中心海域、格陵兰和挪威海;Laxon13算法估算结果相对于IceBridge观测结果与其他算法相比,具有最小的平均偏差和均方根误差,是卫星测高估算海冰厚度的最优算法。     

2002年——2011年北极海冰时空变化分析

基于2002年-2011年AMSR-E海冰密集度数据, 分析了北极海冰的时空变化特征及其原因。结果表明海冰外缘线面积每年减小8.28×10⁴ km², 下降趋势最快的季节为夏季, 下降速度是1979年-2006年的两倍多, 而且海冰密集度也在降低。2003年、2004年的冰情相对较重, 2007年海冰面积最小。长期冰在2002年-2010年间减少了近30%, 减少的区域主要在波弗特海、楚科奇海、东西伯利亚海、拉普贴夫海、喀拉海以及由这些边缘海向北极方向延伸的北冰洋的广大区域, 长期冰减少的地方大部分为季节性海冰增加的地方。海冰面积与年平均气温之间有显著的负相关关系, 随着全球气候变暖的加剧, 这种减小趋势将会持续。     

北极一年海冰表面积雪深度遥感反演与时序分析

北极海冰表面的积雪深度是重要的地球物理变量, 是研究物质与能量平衡、计算海冰厚度的重要参数。为减小不同被动微波传感器观测数据的系统误差, 对国防气象卫星计划(Defense Meteorological Satellite Program, DMSP)F17-SSMIS与F13-SSM/I重叠期亮度温度数据进行交叉定标, 建立4个频段48个月尺度定标模型, 并与传统年尺度定标模型进行比较和优选, 在此基础上估算并分析2003-2014年北极一年海冰表面积雪深度变化。结果表明:19H、19V、22V、37V频段1~5月的月尺度模型决定系数高于传统年尺度拟合模型; 2003-2014年, 北极一年海冰表面积雪深度总体呈现下降趋势, 同时积雪深度存在明显的周期性变化, 每年7月积雪深度最小, 9月最大; 东西伯利亚海、拉普捷夫海和巴伦支海海冰表面积雪深度呈现减少的趋势。     

利用CryoSat-2测高数据研究南极威德尔海海冰出水高度时空变化

为了提高南极海冰出水高度的估算精度,以威德尔海为例,基于CryoSat-2卫星测高数据,联合冰桥计划(IceBridge)机载测高数据和科考船走航观测数据,获取应用最低点高程法反演海冰出水高度的最佳估计参数,进而估算并分析了2011—2017年,每年5月—10月威德尔海海冰出水高度的时空变化。结果表明,最佳的出水高度估算方案为采用0.8倍标准差剔除高度计观测值粗差后,选择沿轨10 km数据段并取最小5%的样本点平均值作为局地海面高估算海冰出水高度;近7年来南极威德尔海月均海冰出水高度总体呈现略微变薄的趋势,变化范围在17.9~27.4 cm之间;威德尔海海冰出水高度的分布呈现东薄西厚的特征,较大值主要分布在西威德尔海以及南极半岛东部海域。上述结论可为进一步研究南极海冰厚度变化对气候变化的响应提供参考。