GIS空间数据不确定性与质量控制的研究现状   总被引：28，自引：1，他引：28  

刘大杰  刘春 《测绘工程》2001,10(1):6-10

GIS空间数据不确定性和质量控制的研究是GIS基础理论问题研究中的一个重要内容。文中具体介绍了对该问题研究的几个阶段，对目前这一理论问题的研究现状作了简要介绍，并对GIS数据质量控制的策略提出一些看法。  相似文献   

绝对重力与相对重力混合平差的基准及质量控制   总被引：5，自引：0，他引：5  

杨元喜  郭春喜  刘念  丘其宪 《测绘工程》2001,10(2):11-14,19

绝对重力与相对重力测量混合平差是综合利用各种重力测量资料确定重力网基准，提高重力网综合质量的有效途径，文中首先从重力观测的系统误差入手，讨论重力网平差的函数模型；进而根据两类重力观测信息对重力基准的贡献，分析了不同平差方法所对应的各类基准及基统计意义与可靠性；最后对重力网平差的质量控制方法进行了讨论。  相似文献   

Self‐purification in Upland and Lowland Streams     

Ines Heidenwag  Uta Langheinrich  Volker Lüderitz 《洁净——土壤、空气、水》2001,29(1):22-33

Ecological investigations at four streams in Saxony‐Anhalt have shown that there are considerable differences between the self‐purification power of upland and lowland streams. This result is reflected in chemistry and in microbiology. The structure of the bottom substrate mainly influences the degree of self‐purification in connection with rate of flow and flow velocity. The results and differences are demonstrated using the example of Katzsohlbach in the landscape unit “Mittel‐ and Unterharz” and the stream Olbe in the landscape unit “Magdeburger Börde”.  相似文献   

陆地水水质全球变化研究进展   总被引：1，自引：0，他引：1  

陈静生 《地球科学进展》1992,7(4):71-76

对陆地水水质全球变化研究中的几个问题进行了讨论，包括:陆地淡水水质的全球参比值问题;水质监测的发展及全球淡水水质监测计划;全球淡水水质变化趋势分析。
    相似文献   

浅议如何提高地震前兆观测数据的质量     

张正霞 《山西地震》2006,(4):38-39

文中论述了地震前兆观测数据的采集、处理、入库、报送和共享等具体工作,指出了当前数据报送工作中存在的问题,提出了改进措施,以保障前兆观测数据的连续、完整。为地震监测预报提供可信度较高的资料。  相似文献   

Processing and quality control of flux data during LITFASS-2003   总被引：1，自引：0，他引：1  

Matthias Mauder  Claudia Liebethal  Mathias Göckede  Jens-Peter Leps  Frank Beyrich  Thomas Foken 《Boundary-Layer Meteorology》2006,121(1):67-88

Different aspects of the quality assurance and quality control (QA/QC) of micrometeorological measurements were combined to create a comprehensive algorithm which was then applied to experimental data from LITFASS-2003 (Lindenberg Inhomogeneous Terrain—Fluxes between Atmosphere and Surface: a long term Study). Eddy-covariance measurements of the latent heat flux were the main focus of the QA/QC efforts. The results of a turbulence sensor intercomparison experiment showed deviations between the different eddy-covariance systems on the order of 15%, or less than 30 W m⁻², for the latent heat flux and 5%, or less than 10 W m⁻², for the sensible heat flux. In order to avoid uncertainties due to the post-processing of turbulence data, a comprehensive software package was used for the analysis of experimental data from LITFASS-2003, including all necessary procedures for corrections and quality control. An overview of the quality test results shows that for most of the days more than 80% of the available latent heat flux data are of high quality so long as there are no instrumental problems. The representativeness of a flux value for the target land-use type was analysed using a stochastic footprint model. Different methods to calculate soil heat fluxes at the surface are discussed and a sensitivity analysis is conducted to select the most robust method for LITFASS-2003. The lack of energy balance closure, which was found for LITFASS-2003, can probably be attributed to the presence of low-frequency flux contributions that cannot be resolved with an averaging time of 30 min. Though the QA/QC system has been developed for the requirements of LITFASS-2003, it can also be applied to other experiments dealing with similar objectives.  相似文献   

灌浆自动记录仪在云鹏水电站坝基工程中的应用     

刘开明 《云南地质》2007,26(2):253-256

灌浆自动记录仪可以准确记录灌浆全过程灌浆参数,保证灌浆原始记录资料的稳定、可靠和真实,为合理控制施工过程和正确分析判断注浆效果提供可靠的依据,使灌浆质量得以提高。  相似文献   

基于数据库的大比例尺基础地理数据缩编需要注意的一些问题     

陈四平 《现代测绘》2007,30(5):36-37

提出了基于数据库的大比例尺基础地理数据缩编需要注意的一些问题，并从加强数据设计的完整性、作好数据准备工作，提高自动化处理功能，人机交互辅助缩编，满足地图回放的要求，加强数据质量控制等方面阐述了实现基于数据库缩编的实用方法。  相似文献   

The energy balance experiment EBEX-2000. Part II: Intercomparison of eddy-covariance sensors and post-field data processing methods     

Matthias Mauder  Steven P. Oncley  Roland Vogt  Tamas Weidinger  Luis Ribeiro  Christian Bernhofer  Thomas Foken  Wim Kohsiek  Henk A. R. De Bruin  Heping Liu 《Boundary-Layer Meteorology》2007,123(1):29-54

The eddy-covariance method is the primary way of measuring turbulent fluxes directly. Many investigators have found that these flux measurements often do not satisfy a fundamental criterion—closure of the surface energy balance. This study investigates to what extent the eddy-covariance measurement technology can be made responsible for this deficiency, in particular the effects of instrumentation or of the post-field data processing. Therefore, current eddy-covariance sensors and several post-field data processing methods were compared. The differences in methodology resulted in deviations of 10% for the sensible heat flux and of 15% for the latent heat flux for an averaging time of 30 min. These disparities were mostly due to different sensor separation corrections and a linear detrending of the data. The impact of different instrumentation on the resulting heat flux estimates was significantly higher. Large deviations from the reference system of up to 50% were found for some sensor combinations. However, very good measurement quality was found for a CSAT3 sonic together with a KH20 krypton hygrometer and also for a UW sonic together with a KH20. If these systems are well calibrated and maintained, an accuracy of better than 5% can be achieved for 30-min values of sensible and latent heat flux measurements. The results from the sonic anemometers Gill Solent-HS, ATI-K, Metek USA-1, and R.M. Young 81000 showed more or less larger deviations from the reference system. The LI-COR LI-7500 open-path H₂O/CO₂ gas analyser in the test was one of the first serial numbers of this sensor type and had technical problems regarding direct solar radiation sensitivity and signal delay. These problems are known by the manufacturer and improvements of the sensor have since been made. The National Center for Atmospheric Research is supported by the National Science Foundation.  相似文献   

风廓线雷达资料质量控制及其同化应用   总被引：6，自引：0，他引：6  

张旭斌  万齐林  薛纪善  丁伟钰  李昊睿 《气象学报》2015,73(1):159-176

为更好地同化风廓线雷达观测资料开展了相应的质量控制与同化应用研究。针对2013年5月广东地区13部风廓线雷达的观测数据,采用经验正交函数(EOF) 分析方法对其进行质量控制。相比原始观测,经过质量控制的风场提高(降低)了来自时空大(小)尺度的贡献,较好地滤除了小尺度高频脉动,也较好地保留了大尺度平均状态与局地中小尺度系统的共同影响,并且更加接近ECMWF再分析场。此外,还对质量控制后的数据进行了垂直稀疏化。分别计算了质量控制前、后风廓线雷达观测与NCEP 6 h预报场的差值,对比差值的特征发现,经过质量控制的数据的观测增量更好地满足了高斯分布与无偏假设。针对一个实际天气个例,基于GRAPES 3D-Var同化系统,分析了质量控制后的风廓线雷达资料对模式分析与预报的影响。试验表明,在循环同化过程中加入风廓线雷达资料可以更好地描述模式初始场低层风场的特征,从而对强降水的位置与强度做出更好的预报。针对2013年5月的批量试验表明,同化风廓线雷达资料使短期降水预报有明显的改善。  相似文献