联合GPS和SARAL卫星测高数据构建南极Dome A区域DEM          下载免费PDF全文

杨全明杨元德  王泽民宋国云 刘艳霞 《极地研究》2017,29(2):204-209

南极冰盖数字高程模型(digital elevation model,DEM)对南极环境变化和地形研究具有重要作用,利用GPS实测数据和卫星测高数据建立DEM是构建南极冰盖表面DEM的重要方法。考虑到实测GPS数据的精度较高,而卫星测高的空间分辨率占优,本文探讨综合利用这两种数据构建南极Dome A区域DEM。法国国家空间研究中心和印度空间研究组织共同研制的SARAL卫星是Envisat的后续卫星,搭载的Alti Ka雷达高度计首次采用了Ka波段,可以极大减小电离层的影响,提高测距精度和卫星数据的空间分辨率。本文首先利用中国南极第29次科学考察在Dome A区域的实测GPS数据对SARAL数据进行精度评定,然后利用实测GPS数据对SARAL测高数据进行高程修正,联合GPS数据获取得到了Dome A区域300 m分辨率的DEM。结果表明SARAL的高程精度为0.615 m,而联合GPS数据能改善DEM精度,提高到0.261 m。  相似文献   

基于统一高度Cressman方法的地面2m气温客观分析          下载免费PDF全文

朱文刚  李昌义  车军辉 《山东气象》2021,41(2):138-148

针对离散站点资料格点化的业务需求及 Cressman 方法在地形复杂区域客观分析存在的问 题,利用山东及周边省自动气象站观测的 2 m气温和 ECMWF预报的海上 2 m气温,结合山东省中尺度数值预报位温递减率、90 m分辨率 SRTM高程数据,采用统一高度 Cressman 方法对山东省地面2 m气温进行客观分析,生成了逐 1 h、0.01°×0.01°高分辨率的地面 2 m气温格点产品。结果表明,统一高度 Cressman 方法的客观分析格点产品在地形复杂区域的分析更合理,月平均误差基本在±1 ℃以内,鲁中山区地形高度较高区域月平均误差略大于鲁西北、鲁西南、鲁东南和山东半岛等地的平原地区,气温偏低的10、11、12月温度准确率均略低于 5、6、7、8、9 月;2020 年 5—12 月平均误差为－0.0039 ℃,平均绝对误差为 0.1469 ℃,均方根误差为 0.3597 ℃,2 ℃以内准确率为 99.64%,1 ℃以内准确率为 98.24%,各项检验指标均较优。总体上统一高度 Cressman 客观分析格点产品质量接近中国气象局陆面数据同化系统（ HRCLDAS ）高分辨率格点实况产品。  相似文献   

狭长区域下基于正交法的GPS高程拟合研究     

郭英起  伊晓东  黄瑞金  李胜 《测绘工程》2007,16(6):19-21

将GPS点大地高直接转换成正常高,越来越广泛地应用于建立高程控制网的实践中。而要保证GPS点高程精度的关键是高程异常拟合模型选择的合理性。文中介绍了在狭长带状区域下利用正交函数法拟合GPS点高程的数学模型。并利用试验数据进行比对分析。结果表明,文中提出的方法计算具有算法稳定,成果合理的特点。  相似文献   

全站仪三角高程新方法及精度估算   总被引：2，自引：0，他引：2  

张勇  王波 《测绘工程》2007,16(6):46-48

利用传统三角高程原理和方法推导一种全站仪三角高程测量新方法计算公式。该方法的优点是在观测的过程中不需要量测仪器和棱镜高,从而达到提高精度的目的;并利用误差传播定律进行精度估算和分析,通过与《工程测量规范》中相应的水准闭合差比较,得出在一定条件下该方法可以代替三、四等水准测量。此方法用在施工测量中可以大大地提高工作效率和缩短工程工期。  相似文献   

一种基于MAD改进的GNSS高程时间序列粗差探测方法     

鲁铁定  何锦亮  徐华卿  贺小星 《大地测量与地球动力学》2022,42(4):349-354

针对GNSS高程时间序列中不可避免地含有粗差,以及在非线性、不平稳性的高程时间序列中粗差难以探测的问题,在传统MAD方法基础上,构建一种引入小波分析的WT-MAD粗差探测方法.利用模拟数据和LHAZ、BJFS、TWTF三个IGS站的实测高程数据进行实验,将WT-MAD法与基于最小二乘的3σ法、IQR法和MAD法进行对比...  相似文献   

一种TIN生成算法及其三维显示   总被引：12，自引：1，他引：11  

栾晓岩 《海洋测绘》2004,24(5):39-41

基于三角网的数字高程模型可以逼真地表现地表形态。在Visual C 6.0集成开发环境中构建基于等高线数据的三角网,提高构网的速度和精度,利用0penGL完成基于TIN的三维地貌显示。  相似文献   

Application of Structure‐from‐Motion photogrammetry to river restoration          下载免费PDF全文

Baptiste Marteau  Damià Vericat  Chris Gibbins  Ramon J. Batalla  David R. Green 《地球表面变化过程与地形》2017,42(3):503-515

Structure‐from‐Motion (SfM) photogrammetry is now used widely to study a range of earth surface processes and landforms, and is fast becoming a core tool in fluvial geomorphology. SfM photogrammetry allows extraction of topographic information and orthophotos from aerial imagery. However, one field where it is not yet widely used is that of river restoration. The characterisation of physical habitat conditions pre‐ and post‐restoration is critical for assessing project success, and SfM can be used easily and effectively for this purpose. In this paper we outline a workflow model for the application of SfM photogrammetry to collect topographic data, develop surface models and assess geomorphic change resulting from river restoration actions. We illustrate the application of the model to a river restoration project in the NW of England, to show how SfM techniques have been used to assess whether the project is achieving its geomorphic objectives. We outline the details of each stage of the workflow, which extend from preliminary decision‐making related to the establishment of a ground control network, through fish‐eye lens camera testing and calibration, to final image analysis for the creation of facies maps, the extraction of point clouds, and the development of digital elevation models (DEMs) and channel roughness maps. The workflow enabled us to confidently identify geomorphic changes occurring in the river channel over time, as well as assess spatial variation in erosion and aggradation. Critical to the assessment of change was the high number of ground control points and the application of a minimum level of detection threshold used to assess uncertainties in the topographic models. We suggest that these two things are especially important for river restoration applications. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

结合ICESat-2和GEDI的中国东南丘陵地区ASTERGDEM高程精度评价与修正     

焦怀瑾  陈崇成  黄洪宇 《地球信息科学学报》2023,25(2):409-420

星载激光雷达ICESat-2和GEDI可以为数字高程模型产品的精度评价与修正提供全球覆盖的、可靠的高精度参考数据源。然而,现有的DEM修正方法主要是针对DEM误差中的植被高信号且多采用线性回归模型。为此,本文分析了ASTER GDEM v3精度与土地覆盖类型、高程、坡度、起伏度及植被覆盖率的关系。在此基础上,提出了一种考虑上述多种精度影响因素并结合XGBoost和空间插值的DEM误差修正方法。结果分析表明:原始ASTER GDEM的误差整体呈正态分布,平均误差为-3.463 m,存在较大负偏差,高程精度随着高程、坡度、起伏度及植被覆盖率VCF的增大呈降低趋势;经过修正后,ASTER GDEM平均误差降低到了-0.233 m,负偏差得到有效改善,整体平均绝对误差降低了26.04%,整体均方差降低了23.56%,耕地、林地、草地、湿地、水域及人造地表的DEM平均绝对误差和均方差都有不同程度的降低;本文提出的方法对多种特征要素与地形误差间的非线性关系进行拟合建模,在研究区取得了较好的修正效果。  相似文献   

Spatio‐temporal tracer variability in the glacier melt end‐member — How does it affect hydrograph separation results?          下载免费PDF全文

Jan Schmieder  Jakob Garvelmann  Thomas Marke  Ulrich Strasser 《水文研究》2018,32(12):1828-1843

Geochemical and isotopic tracers were often used in mixing models to estimate glacier melt contributions to streamflow, whereas the spatio‐temporal variability in the glacier melt tracer signature and its influence on tracer‐based hydrograph separation results received less attention. We present novel tracer data from a high‐elevation catchment (17 km², glacierized area: 34%) in the Oetztal Alps (Austria) and investigated the spatial, as well as the subdaily to monthly tracer variability of supraglacial meltwater and the temporal tracer variability of winter baseflow to infer groundwater dynamics. The streamflow tracer variability during winter baseflow conditions was small, and the glacier melt tracer variation was higher, especially at the end of the ablation period. We applied a three‐component mixing model with electrical conductivity and oxygen‐18. Hydrograph separation (groundwater, glacier melt, and rain) was performed for 6 single glacier melt‐induced days (i.e., 6 events) during the ablation period 2016 (July to September). Median fractions (±uncertainty) of groundwater, glacier melt, and rain for the events were estimated at 49±2%, 35±11%, and 16±11%, respectively. Minimum and maximum glacier melt fractions at the subdaily scale ranged between 2±5% and 76±11%, respectively. A sensitivity analysis showed that the intraseasonal glacier melt tracer variability had a marked effect on the estimated glacier melt contribution during events with large glacier melt fractions of streamflow. Intra‐daily and spatial variation of the glacier melt tracer signature played a negligible role in applying the mixing model. The results of this study (a) show the necessity to apply a multiple sampling approach in order to characterize the glacier melt end‐member and (b) reveal the importance of groundwater and rainfall–runoff dynamics in catchments with a glacial flow regime.  相似文献   

Development and application of a spatially‐distributed Arctic hydrological and thermal process model (ARHYTHM)     

Ziya Zhang  Douglas L. Kane  Larry D. Hinzman 《水文研究》2000,14(6):1017-1044

A process‐based, spatially distributed hydrological model was developed to quantitatively simulate the energy and mass transfer processes and their interactions within arctic regions (arctic hydrological and thermal model, ARHYTHM). The model first determines the flow direction in each element, the channel drainage network and the drainage area based upon the digital elevation data. Then it simulates various physical processes: including snow ablation, subsurface flow, overland flow and channel flow routing, soil thawing and evapotranspiration. The kinematic wave method is used for conducting overland flow and channel flow routing. The subsurface flow is simulated using the Darcian approach. The energy balance scheme was the primary approach used in energy‐related process simulations (snowmelt and evapotranspiration), although there are options to model snowmelt by the degree‐day method and evapotranspiration by the Priestley–Taylor equation. This hydrological model simulates the dynamic interactions of each of these processes and can predict spatially distributed snowmelt, soil moisture and evapotranspiration over a watershed at each time step as well as discharge in any specified channel(s). The model was applied to Imnavait watershed (about 2·2 km²) and the Upper Kuparuk River basin (about 146 km²) in northern Alaska. Simulated results of spatially distributed soil moisture content, discharge at gauging stations, snowpack ablations curves and other results yield reasonable agreement, both spatially and temporally, with available data sets such as SAR imagery‐generated soil moisture data and field measurements of snowpack ablation, and discharge data at selected points. The initial timing of simulated discharge does not compare well with the measured data during snowmelt periods mainly because the effect of snow damming on runoff was not considered in the model. Results from the application of this model demonstrate that spatially distributed models have the potential for improving our understanding of hydrology for certain settings. Finally, a critical component that led to the performance of this modelling is the coupling of the mass and energy processes. Copyright © 2000 John Wiley & Sons, Ltd.  相似文献