共查询到19条相似文献，搜索用时 328 毫秒
1.
利用中国陕西地区三期国家一等水准网的平差成果、两期二等水准网成果、两期陕西省高程控制网成果、两期全球导航卫星系统（global navigation satellite system, GNSS）大地控制网成果、陆态网络等工程连续运行基准站及流动站成果、地理国情监测成果,分析陕西地区最新垂直运动趋势。结果表明:GNSS垂直运动与水准垂直运动趋势整体一致;20世纪70年代至2018年,关中平原垂直运动呈下降趋势,关中平原周边山区及高原垂直运动呈上升趋势;陕北地区地壳垂直运动总体上呈现上升趋势,平均上升速度约为4 mm/a;关中平原总体呈下降趋势,下降最大速度为6 mm/a;陕南地区也呈上升趋势,平均上升速度约为3 mm/a;陕北、西安局部区域的不均匀地面沉降灾害严重。 相似文献
2.
3.
4.
冰期后地壳回弹运动的空间大地测量检测 总被引：3，自引：0，他引：3
本文讨论了用空间大利测量地壳运动预测量（基线变化率、站速度）检测冰期后地壳加弹运动的方法和结果。通过最近获得的空间大地测量地壳运动观测结果与最新冰期后地壳回弹模型ＩＣＥ－４Ｇ的估计值的比较和相关分析，发现两者有较好的一致性，相关系数高达０．８０￣０．９０，说明目前的空间大地测量技术已能够检测出１￣１０ｍｍ／ａ量级的冰期后地壳回弹运动。但实测结果比ＩＣＥ－４Ｇ估计值在绝对值上总体偏大约１．５倍，有可 相似文献
5.
6.
根据1998～2009年的GPS基准站和重复观测资料,获得了1 041个点在2000中国大地坐标系下的速度,研究了利用多面函数建立速度场模型的关键问题:核函数的选择、平滑因子的确定以及结点的确定,并利用多面函数建立了覆盖中国大陆范围的分布均匀、有实用价值的中国地壳水平运动整体速度场。 相似文献
7.
利用2000~2012年的IGS电离层TEC数据,研究了南北半球电离层TEC的非对称性。首先对南北半球TEC日平均值的不对称指数(AI)进行了研究,结果表明,AI的极大值的绝对值集中在0.4左右,极小值的绝对值集中在0.3左右,表明南北半球电离层TEC存在数值上的非对称性;通过傅里叶变换,发现AI存在1 a和1/3 a周期;每年北半球电离层TEC高于南半球电离层TEC的时间比例均大于50%,平均值为58%,表明了南北半球电离层TEC存在时间上的非对称性。然后进一步分析了南北半球TEC年平均值的差异,发现了北半球TEC年平均值高于南半球的规律,2000~2012年的南北半球TEC年平均值的不对称指数在0.036左右。最后从全球大气分布及运动规律的南北非对称性和热层年度变化赤道非对称性两个角度,对南北半球电离层TEC的非对称性产生的原因做了初步分析。 相似文献
8.
长距离动态GPS数据处理方法与汶川地震引起的动态地壳形变特征分析 总被引：1，自引：0，他引：1
利用长距离GPS动态数据处理方法,根据四川GPS网地震前后的观测数据,计算出了四川GPS网各站点地震前后的位移量。以相对稳定的雅安站为参考站,计算出了绵阳站和郫县站的动态变形序列。汶川地震动态地壳变形分析结果表明,地震期间,绵阳站和郫县站的主运动朝向西北方向,同时伴随有小幅摆动。在高程方向,绵阳站出现先上升后下降的运动特征,郫县站出现上下波动特征。 相似文献
9.
搜集了全球约4 000个GNSS测站实测数据(站坐标和速度场信息),对固体地球体积及其变化率进行计算分析。采用板块运动模型插值方法对台站进行插值,使全球测站分布更加均匀。利用Delaunay数学模型计算固体地球体积及其变化率的结果发现:基于板块运动模型进行台站插值可以有效地提高计算结果的误差精度,不会对地球最终形态变化结论产生影响,台站数量及其分布均匀程度对计算最终结果影响较大。 相似文献
10.
采用中国地壳运动观测网络工程厦门基准站的GPS观测数据以及厦门验潮站的验潮数据,计算了厦门海域的海平面绝对变化速度,并就高程变化问题作了深入讨论,表明点位高程变化呈周期性,几期GPS连续观测受其影响不能得出实际的高程线性变化速率,指出了要监测验潮站的地壳垂直运动,最好采用多年连续的GPS观测数据。 相似文献
11.
利用IGS提供的重新处理的周解,采用一阶形变法反演了2000～2009年的地心运动。结果表明,X、Y、Z方向的周年项振幅分别为3.72mm,3.06mm和8.95mm;Z方向的相位表明,2月份左右北半球的表面负载最大,8月份左右南半球的表面负载最大,南北半球存在明显的季节性质量交换。 相似文献
12.
全球GPS测站垂向周年变化统计改正模型的建立 总被引：1，自引：1，他引：0
对GPS测站坐标进行非线性变化的研究和建模,是削弱测站非线性运动的有效途径。由于导致测站坐标非线性变化的机制具有多样性和复杂性,目前还未能建立一个包含多种机制影响的理论改正模型来削弱测站的非线性运动。本文基于全球近500个实测的GPS测站垂向坐标残差时间序列,研究发现了测站垂向坐标周年项的全球分布规律,并分别针对南北半球构建了两个基于实测数据的周年变化统计改正模型。试验表明,本文提出的统计改正模型能削弱全球大部分GPS测站30%~50%的垂向坐标残差。 相似文献
13.
天顶对流层延迟(zenith tropospheric delay,ZTD)是影响GPS定位精度的关键因素,为了提高ZTD的预测精度,提出一种基于相空间重构的高斯过程回归预测模型。针对ZTD时间序列的混沌特性,利用国际GNSS服务(International GNSS Service,IGS)站提供的ZTD数据,采用Cao方法确定嵌入维数,对ZTD数据进行相空间重构,探究高斯过程(Gaussian process,GP)模型对12个位于南、北半球不同纬度等级IGS站的ZTD预测精度和准确性。为了验证GP模型的有效性,将预测结果分别与原始数据和反向传播(back propagation,BP)神经网络模型预测结果作对比分析,进一步探究不同时间对ZTD预测精度的影响,并分析了经度和海拔对ZTD预测精度的影响。结果表明,GP模型预测结果的均方根误差(root mean square error,RMSE)达到mm级,GP模型与理论值的相关性达到0.997,预测精度指标明显优于BP神经网络模型;GP模型在南半球的预测精度高于北半球,且在高纬地区的RMSE小于3.6 mm,更适用于高纬地区的对流层延迟预测;在研究时域内,GP模型在大部分站点对晚上的预测精度高于白天,经度对ZTD预测精度的影响不明显,海拔与ZTD预测精度呈正比。 相似文献
14.
电离层误差是影响单频用户机定位精度的主要误差源。卫星导航系统播发电离层模型改正参数供用户使用,模型改正精度会对定位结果产生直接影响。北斗卫星导航系统根据连续监测站实测数据,计算并发播地理坐标系下8参数Klobuchar电离层模型参数,且每2 h更新一次。为了科学评估北斗电离层模型改正效果,文中基于北斗最新观测数据,首先,以CODE提供的GIM模型作为比对基准,详细分析了不同纬度地区、不同时间段内的电离层模型改正精度;其次,分别按照以下定位模式进行计算:1)北斗单频不加电离层改正,2)北斗单频+北斗K8模型,3)北斗单频+GPS K8模型,并分析了电离层改正残差对定位结果影响大小。结果表明,北斗电离层模型改正精度在北半球优于南半球,中纬度地区改正效果最好,其改正残差RMS均值在0.6 m左右,往低纬和高纬度地区呈递减趋势;北京地区北斗单频+北斗K8模型定位精度优于GPS K8模型。 相似文献
15.
组合GPS和VLBI数据建立板块运动模型 总被引：6，自引：0，他引：6
利用GPS和VLBI的组合数据,解算了北美、欧亚、太平洋等12板块之间的相对运动欧拉矢量,得到了实测的板块运动模型GVM1。与地学模型(NUVEL1A)的比较指出,GVM1大体上与地学模型一致;EURANOAM的极位置与NUVEL1A的相应极比较接近,旋转速率略微偏大;澳大利亚板块在最近几年内是稳定的;太平洋板块与其他板块对的极位置与地学模型较为接近,这表明多种技术的组合数据提高了板块运动模型建立的精确性和可靠性。 相似文献
16.
M. Krishnapriya A. Bhuvana Chandra Rabindra K. Nayak N. R. Patel P. V. N. Rao V. K. Dadhwal 《Journal of the Indian Society of Remote Sensing》2018,46(2):309-320
A study on seasonal and inter-annual variability of the atmospheric CO2 is carried out based on National Oceanic and Atmospheric Administration Carbon Tracker (NOAACT) re-analysis and satellite measurements of mid-troposphere CO2 by Atmosphere Infrared Sounder on board NASA’s Aqua and lower troposphere CO2 by Greenhouse-gas Observing Satellite. Seasonal and non-seasonal components of each time series were extracted by means of least square based harmonic analysis procedure. The data of surface CO2 fluxes used in the NOAACT are also analyzed to examine its relationship with the atmosphere CO2 variability at different time scales. There exists good consistency between NOAACT analysis and satellite observations in their respective seasonal harmonics and climatology. Surface layer CO2 exhibits large climatological mean over the regions of major anthropogenic sources together with strong seasonal cycle over the humid and cold climatic terrestrial regions especially over the northern hemisphere. Existence of high coherency with the different components of the surface fluxes shows that surface layer atmosphere CO2 seasonality is primarily contributed from the terrestrial ecosystem exchanges and secondarily by anthropogenic and oceanic exchanges. The mid-troposphere CO2 exhibits large values associated with climatology and amplitudes of semi-annual and annual cycles over the northern extra tropics and Polar Regions along with a gradual decreasing trend from northern to southern hemisphere. Inter-annual variability of atmospheric CO2 in the NOAACT in some extent is consistent with the satellite observations. Large scale circulation patterns, its fluctuations associated with ENSO events and large scale ecosystem disturbances have significant influence on the inter-annual variability. 相似文献
17.
AbstractThe order of the constellations in the following catalogue is that of the list in Ptolemy's “Almagest, except that the modern groups in the northern hemisphere are inserted after Ptolemy's northern and before his zodiacal constellations, while the modern groups in the southern hemisphere follow the last of his list. The constellation-name in italic capitals is the Latin form in general use. It is followed by the English translation where necessary and by the French and German versions. The Greek and Arabic names, with their authorities, are then given and translated where they differ in meaning from the Latin. 相似文献
18.
Phenology is a sensitive and critical feature of vegetation and is a good indicator for climate change studies. The global inventory modelling and mapping studies (GIMMS) normalized difference vegetation index (NDVI) has been the most widely used data source for monitoring of the vegetation dynamics over large geographical areas in the past two decades. With the release of the third version of the NDVI (GIMMS NDVI3g) recently, it is important to compare the NDVI3g data with those of the previous version (NDVIg) to link existing studies with future applications of the NDVI3g in monitoring vegetation phenology. In this study, the three most popular satellite start of vegetation growing season (SOS) extraction methods were used, and the differences between SOSg and SOS3g arising from the methods were explored. The amplitude and the peak values of the NDVI3g are higher than those of the NDVIg curve, which indicated that the SOS derived from the NDVIg (SOSg) was significantly later than that derived from the NDVI3g (SOS3g) based on all the methods, for the whole northern hemisphere. In addition, SOSg and SOS3g both showed an advancing trend during 1982–2006, but that trend was more significant with SOSg than with SOS3g in the results from all three methods. In summary, the difference between SOSg and SOS3g (in the multi-year mean SOS, SOS change slope and the turning point in the time series) varied among the methods and was partly related to latitude. For the multi-year mean SOS, the difference increased with latitude intervals in the low latitudes (0–30°N) and decreased in the mid- and high-latitude intervals. The GIMMS NDVI3g data-sets seemed more sensitive than the GIMMS NDVIg in detecting information about the ground, and the SOS3g data were better correlated both with the in situ observations and the SOS derived from the Moderate Resolution Imaging Spectroradiometer NDVI. For the northern hemisphere, previous satellite measures (SOS derived from GIMMS NDVIg) may have overestimated the advancing trend of the SOS by an average of 0.032 d yr–1. 相似文献
19.
Dudy D. Wijaya Haris Haralambous Christina Oikonomou Wedyanto Kuntjoro 《Journal of Geodesy》2017,91(9):1117-1133
The critical frequency of ionospheric F2 layer (foF2) is a measure of the highest frequency of radio signal that may be reflected back by the F2 layer, and it is associated with ionospheric peak electron density in the F2 layer. Accurate long-term foF2 variations are usually derived from ionosonde observations. In this paper, we propose a new method to observe foF2 using a stand-alone global positioning system (GPS) receiver. The proposed method relies on the mathematical equation that relates foF2 to GPS observations. The equation is then implemented in the Kalman filter algorithm to estimate foF2 at every epoch of the observation (30-s rate). Unlike existing methods, the proposed method does not require any additional information from ionosonde observations and does not require any network of GPS receivers. It only requires as inputs the ionospheric scale height and the modeled plasmaspheric electron content, which practically can be derived from any existing ionospheric/plasmaspheric model. We applied the proposed method to estimate long-term variations of foF2 at three GPS stations located at the northern hemisphere (NICO, Cyprus), the southern hemisphere (STR1, Australia) and the south pole (SYOG, Antarctic). To assess the performance of the proposed method, we then compared the results against those derived by ionosonde observations and the International Reference Ionosphere (IRI) 2012 model. We found that, during the period of high solar activity (2011–2012), the values of absolute mean bias between foF2 derived by the proposed method and ionosonde observations are in the range of 0.2–0.5 MHz, while those during the period of low solar activity (2009–2010) are in the range of 0.05–0.15 MHz. Furthermore, the root-mean-square-error (RMSE) values during high and low solar activities are in the range of 0.8–0.9 MHz and of 0.6–0.7 MHz, respectively. We also noticed that the values of absolute mean bias and RMSE between foF2 derived by the proposed method and the IRI-2012 model are slightly larger than those between the proposed method and ionosonde observations. These results demonstrate that the proposed method can estimate foF2 with a comparable accuracy. Since the proposed method can estimate foF2 at every epoch of the observation, it therefore has promising applications for investigating various scales (from small to large) of foF2 irregularities. 相似文献