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11.
在利用GNSS进行像素基电离层层析时,多尺度层析方法利用权重因子将反演区域不同像素层析模型结合在一起,最终得到电离层电子密度反演结果,可以有效地解决电离层层析过程中不适应问题和最终的电离层电子密度失真现象。在多尺度电离层层析中,不同像素尺度层析模型之间权重是影响最终的电离层电子密度精度的重要因素。为了获得高精度电离层层析模型,考虑到权重因子存在着等式和不等式限制条件,采用解决最优化问题的罚函数法确定不同像素尺度电离层层析模型之间的权重。通过采用实测GNSS观测数据进行电离层多尺度电离层层析,对比了多尺度层析模型的各个子模型建模精度并进行分析,同时将罚函数法获得的模型精度与其他确权方法进行了对比,该方法可以有效地应用于多尺电离层度层析,且最终的层析模型精度优于其他确权方法,更优于单尺度电离层层析模型精度。 相似文献
12.
BDS三频观测条件下可以组合得到具有优良特性的虚拟载波观测量,有利于改善非差观测数据的周跳实时探测与修复。文中提出一种基于BDS三频非差数据的周跳实时探测与修复模型:首先,采用消电离层无几何HMW组合观测量探测和修复EWL周跳;然后,将经过修复的EWL观测量与WL组合消除几何相关项,忽略电离层延迟残差进而确定WL周跳;最后采用经过修复的WL观测量与NL组合形成无几何观测量,并通过优化载波相位组合确定电离层延迟的变化量以探测和计算NL周跳,并通过简单变换得到原始载波观测量的周跳值。通过实测BDS三频数据对模型可行性进行验证分析,结果表明,即使在30s的采样率以及电离层活动活跃条件下,该模型都可有效实时探测和修复各类周跳。 相似文献
13.
针对BDS常规实时动态定位(RTK)中,随着流动站与参考站间的距离增加,大气延迟误差的空间相关性大大降低,影响了整周模糊度的快速解算和流动站位置信息的解算精度问题。该文研究了一种基于非差观测误差的BDS中长距离常规RTK定位算法,采用非差误差改正方法为流动站提供误差改正,利用参考站的非差误差改正数以单颗卫星为对象进行误差改正。对电离层延迟误差和相对天顶对流层延迟误差进行参数估计,处理电离层延迟误差和对流层延迟误差的影响。最后通过BDS实测数据对该算法进行了算法验证和结果分析。实验结果表明,该算法可以实现BDS中长距离常规RTK的快速定位,并获得厘米级定位精度。 相似文献
14.
Wen-Yao Xu 《Pure and Applied Geophysics》1989,131(3):371-393
Geomagnetically quiet day variations in the polar region are reviewed with respect to geomagnetic field variation, ionospheric plasma convection, electric field and current. Persistently existing field-aligned currents are the main source of the polar regionSq. Consequently, the morphology and variability of the polar regionSq largely depend upon both field-aligned currents and ionospheric conductivity. Since field-aligned currents are the major linkage between the ionosphere and the magnetosphere, the latter is controlled by solar wind state, in particular, the interplanetary magnetic field, the polar regionSq exhibits remarkable IMF dependence. 相似文献
15.
W. Swider 《Pure and Applied Geophysics》1988,127(2-3):403-414
The most meaningful way to compare observations of the daytimeD-region under all ionization conditions, for the purpose of improving our understanding of this region, would appear to be through use of the effective electron recombination coefficient, =q/[e]2, whereq is the ionization production rate, and where [e] is the electron concentration. This ratio apparently increases monotonically with decreasing altitude, and is much less variable than its componentsq and [e]. This parameter appears eminently suitable as a best first order solution to [e] after determiningq. For nighttime conditions, is more sensitive toq. However, an accurate but simple formula exists for the calculation of electron concentrations. 相似文献
16.
Ionospheric scintillation observations of VHF radio signals from FLEETSAT satellite (73°E longitude) at Bhopal from January
1990 to December 1990 have been used to study the characteristic variations of scintillation activity. It is found that scintillation
occurrence is essentially a night-time phenomenon and day-time scintillations are very rare. Annual average nocturnal variation
of percentage occurrence of scintillations shows maximum at around 2100–2200 hours LT. Seasonally, scintillations are most
prominent during equinoxes and least during summer. Geomagnetic disturbances tend to decrease the occurrence of scintillations
in the pre-midnight period. 相似文献
17.
18.
19.
G. A. Mansilla 《Studia Geophysica et Geodaetica》2007,51(4):563-574
An investigation of the response of the mid-high, mid and low latitude critical frequency foF2 to the geomagnetic storm of
15 July 2000 is made. Ground-based hourly foF2 values (proportional to square root of peak electron density of F2-layer) from
four chains of ionospheric stations located in the geographic longitude ranges 10°W–35°E, 60°E–120°E, 130°E–170°E, 250°E–295°E
are used. Relative deviations of foF2 are considered. The main ionospheric effects for the considered storm are: long-duration
negative disturbances at mid-high latitudes in summer hemisphere in sectors where the storm onset occurred in the afternoon/night-time
hours; short-duration positive disturbances in the summer hemisphere at mid-high latitudes in the pre-sunset hours during
the end of main phase-first stage of the recovery; small and irregular negative disturbances in the low latitude winter hemisphere
which predominate during the main phase and first part of the recovery, and positive disturbances in both hemispheres at mid-high
and mid latitudes prior to the storm onset irrespective of the local time. In addition, the validity of some physical mechanisms
proposed to explain the F2 region behaviour during disturbed conditions is considered.
gus-mansilla@hotmail.com 相似文献
20.
The structure of the mid- and high-latitude ionosphere during the November 2004 storm event obtained from GPS observations 总被引:1,自引:1,他引:1
Andrzej Krankowski Irk I. Shagimuratov Lubomir W. Baran Galina Yakimova 《Acta Geophysica》2007,55(4):490-508
GPS data from the International GNSS Service (IGS) network were used to study the development of the severe geomagnetic storm
of November 7–12, 2004, in the total electron content (TEC) on a global scale. The TEC maps were produced for analyzing the
storm. For producing the maps over European and North American sectors, GPS measurements from more than 100 stations were
used. The dense network of GPS stations provided TEC measurements with a high temporal and spatial resolution. To present
the temporal and spatial variation of TEC during the storm, differential TEC maps relative to a quiet day (November 6, 2004)
were created.
The features of geomagnetic storm attributed to the complex development of ionospheric storm depend on latitude, longitude
and local time. The positive, as well as negative effects were detected in TEC variations as a consequence of the evolution
of the geomagnetic storm. The maximal effect was registered in the subauroral/auroral ionosphere during substorm activity
in the evening and night period. The latitudinal profiles obtained from TEC maps for Europe gave rise to the storm-time dynamic
of the ionospheric trough, which was detected on November 7 and 9 at latitudes below 50°N. In the report, features of the
response of TEC to the storm for European and North American sectors are analyzed. 相似文献