scholarly journals Comparative Analysis of the Effect of the Loading Series from GFZ and EOST on Long-Term GPS Height Time Series

2020 ◽  
Vol 12 (17) ◽  
pp. 2822 ◽  
Author(s):  
Shuguang Wu ◽  
Guigen Nie ◽  
Xiaolin Meng ◽  
Jingnan Liu ◽  
Yuefan He ◽  
...  
Keyword(s):  
Time Series ◽  
Phase Difference ◽  
Global Positioning System ◽  
Reduction Rate ◽  
Environmental Loading ◽  
Change Characteristics ◽  
Global Positioning ◽  
Gps Time Series ◽  
Positive Effect

In order to investigate the effect of different loading models on the nonlinear variations in Global Positioning System (GPS) height time series, the characteristics of annual signals (amplitude and phase) of GPS time series, loading series from Deutsche GeoForschungsZentrum, Germany (GFZ) and School and Observatory of Earth Sciences, France (EOST) at 633 global GPS stations are processed and analyzed. The change characteristics of the root mean square (RMS) reduction rate, annual amplitude and phase of GPS time series after environmental loading corrections (ELCs) are then detected. Results show that ELCs have a positive effect on the reduction in the nonlinear deformation contained in most GPS stations around the world. RMS reduction rates are positive at 82.6% stations after GFZ correction and 87.4% after EOST correction, and the average reduction rates of all stations are 10.6% and 15.4%, respectively. As for the environmental loading series from GFZ and EOST, their average annual amplitudes are 2.7 and 3.1 mm, which explains ~40% annual amplitude of GPS height time series (7.2 mm). Further analysis of some specific stations indicates that the annual phase difference between GPS height time series and the environmental loading series is an important reason that affects the reduction rates of the RMS and annual amplitude. The linear relationship between the annual phase difference and the annual amplitude reduction rate is significant. The linear fitting results show that when there is no annual phase difference between GPS and loading series, the reduction rates of the RMS and annual amplitude will increase to the maximum of 15.6% and 41.6% for GFZ, and 22.0% and 46.6% for EOST.

Benchmarking GPS stations: an improved way to identify the GPS sensitivity

2021 ◽  
Author(s):  
Anna Klos ◽  
Jürgen Kusche ◽  
Artur Lenczuk ◽  
Grzegorz Leszczuk ◽  
Janusz Bogusz
Keyword(s):  
Time Series ◽  
Global Positioning System ◽  
Spatial Density ◽  
Earth System ◽  
Global Networks ◽  
The Earth ◽  
Mass Redistribution ◽  
Wide Range ◽  
Global Positioning ◽  
Temporal And Spatial

<p>Global Positioning System (GPS) stations are affected by a plethora of real and system-related signals and errors that occur at various temporal and spatial resolutions. Geophysical changes related to mass redistribution within the Earth system, common mode components, instability of GPS monuments or thermal expansion of ground, all contribute to the GPS-derived displacement time series. Different spatial resolutions that real and system-related errors occur within are covered thanks to the global networks of GPS stations, characterized presently by an unprecedented spatial density. Various temporal resolutions are covered by displacement time series which span even 25 years now, as estimated for the very first stations established. However, since the GPS sensitivity remains unrecognized, retrieving one signal from this wide range of processes may be very uncertain. Up to now, a comparison between GPS-observed displacement time series and displacements predicted by a set of models, as e.g. environmental loading models, was used to demonstrate the accuracy of the model to predict the observed phenomena. Such a comparison is, however, dependent on the accuracy of models and also on the sensitivity of individual GPS stations. We present a new way to identify the GPS sensitivity, which is based on benchmarking of individual GPS stations using statistical clustering approaches. We focus on regional sets of GPS stations located in Europe, where technique-related signals cover real geophysical changes for many GPS permanent stations and those located in South America and Asia, where hydrological and atmospheric loadings dominate other effects. We prove that combining GPS stations into smaller sets improves our understanding of real and system-related signals and errors.</p>

scholarly journals Analyzing Road Coverage of Public Vehicles According to Number and Time Period for Installation of Road Inspection Systems

2020 ◽  
Vol 9 (3) ◽  
pp. 161 ◽  
Author(s):  
Takehiro Kashiyama ◽  
Yoshihide Sekimoto ◽  
Toshikazu Seto ◽  
Ko Ko Lwin
Keyword(s):  
Global Positioning System ◽  
Local Governments ◽  
Inspection System ◽  
Positioning System ◽  
Efficient Operation ◽  
Time Period ◽  
Global Positioning ◽  
Inspection Systems ◽  
Road Inspection

Shortages of engineers and financial resources have made it difficult for municipalities to identify and address problems with aging road infrastructures. To resolve these problems, numerous studies have focused on automating road inspection, including a study in which we developed a smartphone-based road inspection system. For efficient operation of the system, it is necessary to understand the usage of vehicles in which the system will be installed. In this study, we analyzed the usage of public vehicles with long-term global positioning system (GPS) probe data collected from public vehicles operating in Kakogawa city and Fujisawa city in Japan. As a result, we discovered that local governments of the same size have similar tendencies in terms of road coverage. Moreover, we found that installing road inspection systems on only a few public vehicles can cover the entire road inspection area. We anticipate that these results will assist local governments in making informed decisions during the system introduction process and provide an indicator of the accuracy required for road inspection systems to future researchers.

scholarly journals Improved Multi-GNSS PPP Software for Upgrading the DEMETRA Project Time Monitoring Service

Sensors ◽  
2019 ◽  
Vol 19 (20) ◽  
pp. 4389 ◽  
Author(s):  
Wei Huang ◽  
Pascale Defraigne ◽  
Giovanna Signorile ◽  
Ilaria Sesia
Keyword(s):  
Global Positioning System ◽  
Integer Ambiguity ◽  
Noisy Environments ◽  
Long Term Stability ◽  
Royal Observatory ◽  
Global Positioning ◽  
Receiver Clock ◽  
Frequency Transfer ◽  
Monitoring Service

The H2020 DEMETRA project provides short latency clock monitoring services to the time users using the Atomium precise point positioning (PPP) software developed by the Royal Observatory of Belgium. In this paper, three recent updates of the current Atomium software are introduced: adding Galileo signals in the PPP computation; the option to constrain the receiver clock; PPP with integer ambiguity resolution. The advantages of these updates are demonstrated: Combining the Galileo and global positioning system (GPS) signals for PPP time transfer will further improve the frequency stability inside the computation batch; PPP with receiver clock constraint is not only used to reduce the short-term noise of the clock measurements but can also be used for some specific applications to a keep continuous clock solution in the computation batch or retrieve correct clock measurements from extremely noisy environments; the integer PPP allows a continuous clock solution, and improves the mid-term and long-term stability of the frequency transfer compared to the current PPP frequency transfer techniques.

scholarly journals Harmonic Analysis of Multipath Index Time Series in GPS Stations

2015 ◽  
Vol 16 (1) ◽  
pp. 71
Author(s):  
Eniuce Menezes de Souza ◽  
Daniele Barroca Marra Alves ◽  
Fernanda Lang Schumacher
Keyword(s):  
Time Series ◽  
Harmonic Analysis ◽  
Global Positioning System ◽  
Seasonal Variations ◽  
Gps Data ◽  
Positioning System ◽  
Fisher Test ◽  
Multipath Effect ◽  
Global Positioning ◽  
Index Time Series

The identification of the cyclical and seasonal variations can be veryimportant in time series. In this paper, the aim is to identify the presence ofcyclical or seasonal variations in the indices of the multipath effect on continuousGPS (Global Positioning System) stations. Due to the model used to obtain theseindices, there should not have cyclical variations in these series, at least due to themultipath effect. In order to identify the presence of cyclical variations in theseseries, correlograms and Fourier periodograms were analyzed. The Fisher test forseasonality was applied to confirm the presence of statistical significant seasonality.In addition, harmonic models were adjusted to check in which months of the yearthe cyclical effects are occurring in the multipath indices. The possible causes ofthese effects are pointed out, which will direct the upcoming investigations, as wellas the analysis and correlations of other series. The importance of this analysisis mainly due to the fact that errors in the collected signals of these stations willdirectly influence the accuracy of the results of the whole community that directlyor indirectly uses GPS data.

scholarly journals Characterization of the Long-term Radiosonde Temperature Biases in the Lower Stratosphere using COSMIC and Metop-A/GRAS Data from 2006 to 2014

2016 ◽  
Author(s):  
Shu-Peng Ho ◽  
Liang Peng ◽  
Holger Vömel
Keyword(s):  
Global Positioning System ◽  
Lower Stratosphere ◽  
Temperature Measurements ◽  
Global Trend ◽  
Global Positioning ◽  
The Mean ◽  
Geographical Locations

Abstract. Radiosonde observations (RAOBs) have provided the only long-term global in situ temperature measurements in the troposphere and lower stratosphere since 1958. In this study, we use consistently reprocessed Global Positioning System (GPS) radio occultation (RO) temperature data derived from COSMIC and Metop-A/GRAS missions from 2006 to 2014 to characterize the inter-seasonal and inter-annual variability of temperature biases in the lower stratosphere for different sensor types. The results show that the RAOB temperature biases for different RAOB sensor types are mainly owing to i) uncorrected solar zenith angle dependent errors, and ii) change of radiation correction. The mean daytime temperature difference (ΔT) for Vaisala RS92 is equal to 0.18 K in Australia, 0.20 K in Germany, 0.10 K in Canada, 0.13 K in England, and 0.33 K in Brazil. The mean daytime ΔT is equal to −0.06 K for Sippican, 0.71 K for VIZ-B2, 0.66 K for AVK-MRZ, and 0.18 K for Shanghai. The daytime trend of anomalies for Vaisala RS92 and RO temperature at 50 hPa is equal to 0.00 K/5 yrs over United States, −0.02 K/5 yrs over Germany, 0.17 K/5 yrs over Australia, 0.23 K/5 yrs over Canada, 0.26 K/5 yrs over England, and 0.12 K/5 yrs over Brazil, respectively. Although there still exist uncertainties for Vaisala RS92 temperature measurements over different geographical locations, the global trend of temperature anomaly between Vaisala RS92 and RO from June 2006 to April 2014 is within +/−0.09 K/5 yrs globally. Comparing with Vaisala RS80, Vaisala RS90 and sondes from other manufacturers, the Vaisala RS92 seems to provide the best RAOB temperature measurements, which can potentially be used to construct long term temperature CDRs. Results from this study also demonstrate the feasibility to use RO data to correct RAOB temperature biases for different sensor types.

scholarly journals The effect of correlation on uncertainty estimates – with GPS examples

2013 ◽  
Vol 3 (2) ◽  
pp. 111-120 ◽  
Author(s):  
P. Jansson ◽  
C.-G. Persson
Keyword(s):  
Time Series ◽  
Observation Time ◽  
Gps Time Series Analysis ◽  
Uncertainty Estimates ◽  
Stationary Stochastic Processes ◽  
Global Positioning ◽  
Gps Observation ◽  
Measurement Strategies ◽  
Gps Time Series ◽  
Testing Design

Abstract This article deals with the effect of correlation on the estimates of measurement uncertainty, with some focus on Global Positioning Satellite (GPS) time series analysis. Analytical derivations and Monte Carlo simulations form the theoretical basis, which shows that uncompensated correlation produces unrealistic uncertainty estimates. Tools for handling correlation in connection with estimation of uncertainty, construction of confidence intervals, hypothesis testing, design of measurement strategies, and development of tolerances are outlined and demonstrated. The GPS observation time series used in the article has a short to medium range correlation, and can therefore be handled with the presented tools - based on a simple Location-model and stationary stochastic processes.

scholarly journals 1996–2017 GPS position time series, velocities and quality measures for the CORS Network

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Jarir Saleh ◽  
Sungpil Yoon ◽  
Kevin Choi ◽  
Lijuan Sun ◽  
Richard Snay ◽  
...  
Keyword(s):  
Global Positioning System ◽  
Term Stability ◽  
Long Term Stability ◽  
Velocity Models ◽  
Daily Data ◽  
The Us ◽  
Global Positioning ◽  
Position Time Series ◽  
Better Than

Abstract The CORS network is a volunteer-based network of Global Positioning System reference stations located mainly in the US and its territories. We discuss the most recent comprehensive reprocessing of all GPS data collected via this network since 1996. Daily data for GPS weeks 834 through 1933 were reprocessed leading to epoch 2010.0 coordinates and velocities of 3049 stations aligned to IGS14. The updated realization of the US National Spatial Reference System derived in this work has been in use since late 2019. As a validation of the results, the derived velocity field is compared to several other solutions and to three regional geophysical and geodetic velocity models. These comparisons uncovered unstable stations which move differently than the regional kinematics around them. Once these are ignored, we estimate the horizontal and vertical stability of this updated realization to be better than ∼0.3 and ∼0.6 mm/year, respectively. We use the position residuals and estimated uncertainties from this reprocessing to derive long-term stability measures for all active stations serving longer than 3 years. These measures exposed ∼60 CORS with the poorest long-term stability, which have been consequently excluded from serving as mapping control.

scholarly journals SEISMIC STRAIN MAP IN MALAYSIA DERIVED FROM LONG-TERM GLOBAL POSITIONING SYSTEM DATA

2019 ◽  
Vol XLII-4/W16 ◽  
pp. 399-408
Author(s):  
M. S. Mohamad ◽  
W. A. W. Aris ◽  
N. J. Jaffar ◽  
R. Othman
Keyword(s):  
Strain Rate ◽  
Global Positioning System ◽  
Crustal Deformation ◽  
Peninsular Malaysia ◽  
Positioning System ◽  
North Borneo ◽  
Global Positioning ◽  
The Status ◽  
Seismic Strain

Abstract. Series of major earthquakes struck the Sundaland plate as a result of convergence with neighboring plates such as Indian, Australian and Philippine plates. Since then, the Sundaland is experiencing significant crustal deformation that implicate reactivation of local fault and embark question on the status of geohazard and seismic risk. In Malaysia, crustal deformation study by using Global Positioning System (GPS) has been conducted for many years. However, the information of crustal deformation was reported separately and difficult to be archived. In addition, continuous estimation of crustal deformation derived from GPS has to be carried out in order to provide present day seismic status. This study aims at generating a seismic catalog map in Malaysia derived from approximately nine (9) years of GPS data. In this study, derived long-term crustal deformation in the form of coordinate time series (CTS) were converted into yearly strain map. The changes of strain with respect to location of old and active fault line in Malaysia were properly analysed. From the result, the highest changes of strain rate for Peninsular Malaysia happened in 2004 until 2005 and 2012 until 2013 prior to 2004 Acheh earthquake event with the moment magnitude (Mw) and 2012 two strike-slip events in Northern Sumatera with the magnitude of 8.2Mw and 8.6Mw. In North Borneo region, the most significant changes of strain rate happened from 2007 to 2009 and 2011 to 2013. It can be expected that the results will be beneficial in augmenting geohazard mitigation in Malaysia.

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