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An evaluation of potential solar radio emission power threat on GPS and GLONASS performance 总被引：1，自引：1，他引：0
The L-band solar radio emission has recently been regarded as a potential threat to stable GPS and GLONASS performance. However, the threat has not been completely investigated or assessed so far. We evaluate in detail the occurrence of GPS/GLONASS signal tracking failures under the direct exposure of wideband solar radio emission. By means of theoretical analysis, we found that the solar radio emission power level of 1,000?sfu (solar flux units) or higher can cause GPS/GLONASS signal tracking failures especially at L2 frequency. In order to prove this evaluation, we investigated GPS/GLONASS signal tracking failures at L1 and L2 frequencies during power solar flares X6.5 (December 6, 2006) and X3.4 (December 13, 2006). Comparing these events with weaker solar flare X17.2 on October 28, 2003, we found that L2 signal tracking failures appeared when the solar radio emission power exceeds 1,000?sfu. Therefore, our theoretical and experimental results confirm the earlier results by other authors. 相似文献
2.
The state of the ionosphere affects the operational stability of satellite radio navigation systems. The dense network of
GEONET GPS sites on the territory of Japan allows to conduct a thorough investigation of the stability of system operation
at mid-latitudes in different heliogeophysical conditions. This paper considers deterioration in the accuracy of GPS system
positioning due to the effect of a large-scale ionospheric disturbance (an ionospheric bubble) over Japan on February 12,
2000. 相似文献
3.
Ionospheric super-bubble effects on the GPS positioning relative to the orientation of signal path and geomagnetic field direction 总被引：2，自引：2，他引：0
Using GPS data of the Japanese network GEONET, we analyze occurrence of GPS-phase slips and positioning errors during the
geomagnetic storm of February 12, 2000. Although the storm was not intensive, registering a minimum Dst excursion of −133 nT
and a maximum Kp = 6.7 value, it attracted the attention of researchers because of the appearance of a super-bubble at mid-latitudes.
We identified numerous GPS-phase slips in the area of the super-bubble. By the time of the bubble’s appearance, a total of
33% of GPS receivers experienced positioning errors of more than 500 m. Around 13:00 UT, the positioning quality was worse
than 100 m almost all of Japan. We also found that the occurrence of phase slips of the satellite signals depends on the angle
γ between the receiver-satellite line of sight and geomagnetic field lines. The maximum value of GPS-phase slips corresponds
to γ = 0° and 90°. For the satellites positioned close to the magnetic zenith region, the density of phase slips reached 32%.
In addition to carrier-phase slips, the super-bubble caused sharp increases in positioning errors of several hundred meters
at receiver locations below 38°N latitude. As a result, precise positioning was not possible for about 2 h. 相似文献
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A Special Issue on Data Science for Geosciences 总被引：1，自引：0，他引：1
Mathematical Geosciences - 相似文献
6.
V. Demyanov S. Soltani M. Kanevski S. Canu M. Maignan E. Savelieva V. Timonin V. Pisarenko 《Stochastic Environmental Research and Risk Assessment (SERRA)》2001,15(1):18-32
This paper deals with the problem of spatial data mapping. A new method based on wavelet interpolation and geostatistical
prediction (kriging) is proposed. The method – wavelet analysis residual kriging (WARK) – is developed in order to assess
the problems rising for highly variable data in presence of spatial trends. In these cases stationary prediction models have
very limited application. Wavelet analysis is used to model large-scale structures and kriging of the remaining residuals
focuses on small-scale peculiarities. WARK is able to model spatial pattern which features multiscale structure. In the present
work WARK is applied to the rainfall data and the results of validation are compared with the ones obtained from neural network
residual kriging (NNRK). NNRK is also a residual-based method, which uses artificial neural network to model large-scale non-linear
trends. The comparison of the results demonstrates the high quality performance of WARK in predicting hot spots, reproducing
global statistical characteristics of the distribution and spatial correlation structure. 相似文献
7.
Subcrustal density inhomogeneities of Northern Eurasia as derived from the gravity data and isostatic models of the lithosphere 总被引：1，自引：0，他引：1
M. E. Artemjev M. K. Kaban V. A. Kucherinenko G. V. Demyanov V. A. Taranov 《Tectonophysics》1994,240(1-4):249-253
For the territory of Northern Eurasia (6°E–165°W; 30–75°N) the distribution of anomalous masses in the lithosphere has been estimated in accordance with the lithosphere isostatic model. The method of model construction is based on the admittance technique. The experimental admittance presents a relation between the part of the outer load uncompensated by the Moho undulations and the residual gravity field and is used to select the best model. The 1 × 1° averaged values of topography elevations, basement and Moho depths, sedimentary cover density and gravity anomalies have been used as initial data. According to the correlation equation relating the outer load and Moho depths, the mean density contrast between the lower crust and the subcrustal lithosphere is 0.43 g/cm3, but the Moho undulation can not provide complete isostatic equilibrium. In some areas, the part of the outer load uncompensated by Moho undulations may be as large as 107 kg/m2 and the residual gravity field is as intensive as + 260 mGal. Assuming that for loads of wavelength > 200 km, local isostatic compensation is valid, in accordance with the admittance analysis, the anomalous masses compensating for the part of the outer load, which is not compensated by Moho undulations, have to be located partly in the lower crust and in the subcrustal layer. The regional trend of anomalous compensating masses is negative under Western Europe, the Mediterranean, Eastern Asia and adjacent marginal seas, and positive under the East European Platform and Western and Central Asia. The local compensating masses correspond to particular tectonic units. The isostatic gravity anomalies of Northern Eurasia have been determined and the long-wave component of the field reflecting anomalous masses under the isostatic compensation level has been evaluated. 相似文献
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Mathematical Geosciences - The aim of this work is to demonstrate how geologically interpretative features can improve machine learning facies classification with uncertainty assessment. Manual... 相似文献
9.
During geomagnetically disturbed conditions, the accuracy and quality of GPS performance is impaired. Unlike geomagnetically
quiet conditions, magnetic storm conditions are accompanied by an increase in the spherical standard deviation of the position
determination for all types of GPS receivers. In magnetic storm conditions there is an increase in the number of slips of
the one-frequency mode of coordinate determination. We have identified an unambiguous tendency of the slip density of the
one-frequency mode to increase for the ASHTECH and TRIMBLE GPS receivers. For the AOA receivers this tendency was not observed
in any of the cases considered. The slip density in the two-frequency mode of coordinate determination in magnetic storm conditions
increases most dramatically for the ASHTECH receivers. Regarding the TRIMBLE receivers, there is a similar, but less clearly
pronounced, picture. No slips of the two-frequency mode were detected for the AOA receivers in the cases under consideration. 相似文献
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