scholarly journals Spatiotemporal functional modeling of postseismic deformations after the 2011 Tohoku-Oki earthquake

2022 ◽  
Vol 74 (1) ◽  
Author(s):  
Satoshi Fujiwara ◽  
Mikio Tobita ◽  
Shinzaburo Ozawa
Keyword(s):  
Standard Deviation ◽  
Statistical Data ◽  
Functional Model ◽  
Satellite System ◽  
Physical Processes ◽  
Linear Deformation ◽  
Practical Applications ◽  
Long Period ◽  
Global Navigation Satellite ◽  
Physical Phenomena

AbstractPostseismic deformations continue to occur for a long period after major earthquakes. Temporal changes in postseismic deformations can be approximated using simple functions. Since the 2011 Tohoku-Oki earthquake, operating global navigation satellite system stations have been continuously accumulating a remarkable amount of relevant data. To verify the functional model, we performed statistical data processing on postseismic deformations due to this earthquake and obtained their spatiotemporal distribution. Moreover, we approximated the postseismic deformations over a relatively wide area with a standard deviation of residuals of 1 cm for approximately 10 years using a combined functional model of two logarithmic and one exponential functions; however, the residuals from the functional model exhibited a marked deviation since 2015. Although the pattern of postseismic deformations remained unaltered after the earthquake, a change in the linear deformation occurred from 2015 to date. We reduced the overall standard deviation of the residuals of > 200 stations distributed over > 1000 km to < 0.4 cm in the horizontal component by enhancing the functional model to incorporate this linear deformation. Notably, time constants of the functions were similarly applicable for all stations and components. Furthermore, the spatial distribution of the coefficients of each time constant were nonrandom, and the distribution was spatially smooth, with minute changes in the short wavelengths in space. Thus, it is possible to obtain a gridded model in terms of a spatial function. The spatial distributions of short- and long-period components of the functional model and afterslip and viscoelastic relaxation calculated using the physical model were similar to each other, respectively. Each time function revealed a connotation regarding the physical processes, which provided an understanding of the physical phenomena involved in seismogenesis. The functional model can be used to practical applications, such as discerning small variations and modeling for precise positioning. Graphical Abstract

scholarly journals Spatiotemporal Functional Modeling of Postseismic Deformation After the 2011 Tohoku-Oki Earthquake

2021 ◽  
Author(s):  
Satoshi Fujiwara ◽  
Mikio Tobita ◽  
Shinzaburo Ozawa
Keyword(s):  
Steady State ◽  
Standard Deviation ◽  
Functional Model ◽  
Statistical Processing ◽  
Satellite System ◽  
Postseismic Deformation ◽  
Spatial Distributions ◽  
Long Duration ◽  
Global Navigation Satellite ◽  
Physical Phenomena

Abstract Postseismic deformation continues for a long duration after major earthquakes. A previous study has shown that temporal changes in postseismic deformation can be approximated through simple functions. Almost 10 years have passed since the 2011 M9 Tohoku-Oki earthquake, and data at continuously operating global navigation satellite system stations have accumulated. We performed statistical processing of the data on postseismic deformations of this earthquake and obtained and verified their spatiotemporal distribution. We were able to approximate the postseismic deformations over a wide area with a standard deviation of 1 cm for approximately 10 years using two logarithmic and one exponential functions. However, the residuals from the functional model showed a sharp deviation from 2015. Although the pattern of postseismic deformation did not change after the earthquake, a change in steady-state velocity occurred from 2015 and continues till date. By improving the functional model to incorporate this steady-state velocity, we can reduce the overall standard deviation of the residuals of more than 200 stations distributed over more than 1000 km to less than 0.4 cm in the horizontal component. Furthermore, the spatial distributions of the coefficients of each time constant are not random and have a natural spread, which makes it possible to grid model them in terms of a spatial function. The spatial distributions of the short- and long-period components of the functional model and the afterslip and viscoelastic relaxation calculated by a physical model are similar to each other, respectively. Each time function has a meaning related to the physical processes in the underground, which provides an understanding of the physical phenomena involved in seismogenesis.

scholarly journals RTK GNSS-Assisted Terrestrial SfM Photogrammetry without GCP: Application to Coastal Morphodynamics Monitoring

2020 ◽  
Vol 12 (11) ◽  
pp. 1889 ◽  
Author(s):  
Marion Jaud ◽  
Stéphane Bertin ◽  
Mickaël Beauverger ◽  
Emmanuel Augereau ◽  
Christophe Delacourt
Keyword(s):  
Standard Deviation ◽  
Low Cost ◽  
Laser Scanner ◽  
Satellite System ◽  
Mean Error ◽  
Ground Control Points ◽  
Participatory Science ◽  
Gnss Network ◽  
Global Navigation Satellite

The present article describes a new and efficient method of Real Time Kinematic (RTK) Global Navigation Satellite System (GNSS) assisted terrestrial Structure-from-Motion (SfM) photogrammetry without the need for Ground Control Points (GCPs). The system only requires a simple frame that mechanically connects a RTK GNSS antenna to the camera. The system is low cost, easy to transport, and offers high autonomy. Furthermore, not requiring GCPs enables saving time during the in situ acquisition and during data processing. The method is tested for coastal cliff monitoring, using both a Reflex camera and a Smartphone camera. The quality of the reconstructions is assessed by comparison to a synchronous Terrestrial Laser Scanner (TLS) acquisition. The results are highly satisfying with a mean error of 0.3 cm and a standard deviation of 4.7 cm obtained with the Nikon D800 Reflex camera and, respectively, a mean error of 0.2 cm and a standard deviation of 3.8 cm obtained with the Huawei Y5 Smartphone camera. This method will be particularly interesting when simplicity, portability, and autonomy are desirable. In the future, it would be transposable to participatory science programs, while using an open RTK GNSS network.

scholarly journals Preliminary validation of refractivity from a new radio occultation sounder GNOS/FY-3C

2015 ◽  
Vol 8 (9) ◽  
pp. 9009-9044 ◽  
Author(s):  
M. Liao ◽  
P. Zhang ◽  
G. L. Yang ◽  
Y. M. Bi ◽  
Y. Liu ◽  
...  
Keyword(s):  
Standard Deviation ◽  
Radio Occultation ◽  
Weather Prediction ◽  
Satellite System ◽  
Navigation Satellite ◽  
Near Surface ◽  
Vertical Range ◽  
New Radio ◽  
Atmospheric Sounding ◽  
Global Navigation Satellite

Abstract. As a new member of space-based radio occultation sounder, the GNOS (Global Navigation Satellite System Occultation Sounder) mounted on FY-3C has been carrying out the atmospheric sounding since 23 September 2013. GNOS takes a daily measurement up to 800 times with GPS (Global Position System) and Chinese BDS (BeiDou navigation satellite) signals. The refractivity profiles from GNOS are compared with the co-located ECMWF (European Centre for Medium-Range Weather Forecasts) analyses in this paper. Bias and standard deviation have being calculated as the function of altitude. The mean bias is about 0.2 % from the near surface to 35 km. The average standard deviation is within 2 % while it is down to about 1 % in the range 5–30 km where best soundings are usually made. To evaluate the performance of GNOS, COSMIC (Constellation Observing System for Meteorology, Ionosphere and Climate) and GRAS/METOP-A (GNSS Receiver for Atmospheric Sounding) data are also compared to ECMWF analyses as the reference. The results show that GNOS/FY-3C meets the requirements of the design well. It possesses a sounding capability similar to COSMIC and GRAS in the vertical range of 0–30 km, though it needs improvement in higher altitude. Generally, it provides a new data source for global NWP (numerical weather prediction) community.

Aircraft positioning using SPP method in GPS system

2018 ◽  
Vol 90 (8) ◽  
pp. 1213-1220 ◽  
Author(s):  
Kamil Krasuski
Keyword(s):  
Standard Deviation ◽  
Satellite System ◽  
Least Square ◽  
Civil Aviation ◽  
Navigation Satellite ◽  
Least Square Estimation ◽  
Protection Level ◽  
Content Type ◽  
Average Value ◽  
Global Navigation Satellite

PurposeThe purpose of this paper is based on implementation of Global Navigation Satellite System (GNSS) technique in civil aviation for recovery of aircraft position using Single Point Positioning (SPP) method in kinematic mode.Design/methodology/approachThe aircraft coordinates in ellipsoidal frame were obtained based on Global Positioning System (GPS) code observations for SPP method. The numerical computations were executed in post-processing mode in the Aircraft Positioning Software (APS) package. The mathematical scheme of equation observation of SPP method was solved using least square estimation in stochastic processing. In the experiment, airborne test using Cessna 172 aircraft on September 07, 2011 in the civil aerodrome in Mielec was realized. The aircraft position was recovery using observations data from Topcon HiperPro dual-frequency receiver with interval of 1 second.FindingsIn this paper, the average value of standard deviation of aircraft position is about 0.8 m for Latitude, 0.7 m for Longitude and 1.5 m for ellipsoidal height, respectively. In case of the Mean Radial Spherical Error (MRSE) parameter, the average value equals to 1.8 m. The standard deviation of receiver clock bias was presented in this paper and the average value amounts to 34.4 ns. In this paper, the safety protection levels of Horizontal Protection Level (HPL) and Vertical Protection Level (VPL) were also showed and described.Research limitations/implicationsIn this paper, the analysis of aircraft positioning is focused on application the least square estimation in SPP method. The Kalman filtering operation can be also applied in SPP method for designation the position of the aircraft.Practical implicationsThe SPP method can be applied in civil aviation for designation the position of the aircraft in Non-Precision Approach (NPA) GNSS procedure at the landing phase. The typical accuracy of aircraft position is better than 220 m for lateral navigation in NPA GNSS procedure. The limit of accuracy of aircraft position in vertical plane in NPA GNSS procedure is not available.Social implicationsThis paper is destined for people who works in the area of aviation and air transport.Originality/valueThe work presents that SPP method as a universal technique for recovery of aircraft position in civil aviation, and this method can be also used in positioning of aircraft based on Global Navigation Satellite System (GLONASS) code observations.

scholarly journals ASSESSMENT OF VELOCITY ACCURACY OF AIRCRAFT IN THE DYNAMIC TESTS USING GNSS SENSORS

2020 ◽  
Vol 18 (2) ◽  
pp. 301 ◽  
Author(s):  
Kamil Krasuski ◽  
Adam Ciećko ◽  
Grzegorz Grunwald ◽  
Damian Wierzbicki
Keyword(s):  
Standard Deviation ◽  
Research Method ◽  
Satellite System ◽  
Flight Speed ◽  
Motion Model ◽  
Dynamic Tests ◽  
Navigation Data ◽  
Gnss Receivers ◽  
Speed Parameter ◽  
Global Navigation Satellite

The paper presents a new model for determining the accurate and reliable flight speed of an aircraft based on navigation data from the three independent Global Navigation Satellite System (GNSS) receivers. The GNSS devices were mounted on-board of a Cessna 172 aircraft during a training flight in south-eastern Poland. The speed parameter was determined as the resultant value based on individual components from 3 independent solutions of the motion model. In addition, the standard deviation of the determined flight speed values for the Cessna 172 aircraft was determined in the paper. The resultant on-ground and flight speed of the Cessna 172 aircraft ranged from 0.23 m/s to 74.81 m/s, while the standard deviation of the determined speed values varied from 0.01 m/s to 1.07 m/s. In addition, the accuracy of research method equals to -0.46 m/s to +0.61 m/s, in respect to the RTK-OTF solution. The RMS parameter as an accuracy term amounts to 0.07 m/s for the presented research method.

scholarly journals Ionospheric Remote Sensing with GNSS

Encyclopedia ◽  
2021 ◽  
Vol 1 (4) ◽  
pp. 1246-1256
Author(s):  
YuXiang Peng ◽  
Wayne A. Scales
Keyword(s):  
Remote Sensing ◽  
Global Navigation Satellite System ◽  
Charged Particles ◽  
Satellite System ◽  
Upper Atmosphere ◽  
Pivotal Role ◽  
Navigation Satellite ◽  
Plasma Medium ◽  
Physical Processes ◽  
Global Navigation Satellite

The Global Navigation Satellite System (GNSS) plays a pivotal role in our modern positioning, navigation and timing (PNT) technologies. GNSS satellites fly at altitudes of approximately 20,000 km or higher. This altitude is above an ionized layer of the Earth’s upper atmosphere, the so called “ionosphere”. Before reaching a typical GNSS receiver on the ground, GNSS satellite signals penetrate through the Earth’s ionosphere. The ionosphere is a plasma medium consisting of free charged particles that can slow down, attenuate, refract, or scatter the GNSS signals. Ionospheric density structures (also known as irregularities) can cause GNSS signal scintillations (phase and intensity fluctuations). These ionospheric impacts on GNSS signals can be utilized to observe and study physical processes in the ionosphere and is referred to ionospheric remote sensing. This entry introduces some fundamentals of ionospheric remote sensing using GNSS.

scholarly journals A Noise Robust Automatic Radiolocation Animal Tracking System

2021 ◽  
Author(s):  
Liang Wang ◽  
Foivos Diakogiannis ◽  
Scott Mills ◽  
Nigel Bajema ◽  
Ian Atkinson ◽  
...  
Keyword(s):  
Standard Deviation ◽  
Learning Algorithm ◽  
Tracking System ◽  
Sensor Arrays ◽  
Semantic Segmentation ◽  
Satellite System ◽  
Deep Learning Algorithm ◽  
Small Primary ◽  
Noise Robust ◽  
Global Navigation Satellite

Abstract Agriculture is becoming increasingly reliant upon accurate data from sensor arrays, with localization an emerging application in the livestock industry. Ground-based Time Difference of Arrival (TDoA) radiolocation methods have the advantage of being lightweight and exhibit higher energy effciency than methods reliant upon Global Navigation Satellite System (GNSS). Such methods can employ small primary cell batteries, rather than rechargeable cells, and still deliver a multi-year deployment. In this paper, we present a novel deep learning algorithm adapted from a one dimensional U-Net like a convolutional neural network (CNN) model, originally developed for the task of semantic segmentation. This model both converts TDoA sequences directly to positions and reduces positional errors introduced by sources such as multipathing. We have evaluated the model by using simulated animal movements in the form of TDoA position sequences in combination with known distributions of TDoA error. When errors with a standard deviation of 50 m and 100 m are added to simulated TDoA transmissions the model is able to reduce this error to 22 m and 27 m (RMSE) respectively. Without correction, the standard deviation of these errors is on the order of 90 and 200 m. Accordingly, the model can reduce the error by greater than 80 m (> 80%), demonstrating the effectiveness of this novel 1D CNN U-Net like encoder/decoder for error correction of TDoA position estimates.

Performance Evaluation of Single-frequency Precise Point Positioning with GPS, GLONASS, BeiDou and Galileo

2017 ◽  
Vol 70 (3) ◽  
pp. 465-482 ◽  
Author(s):  
Lin Pan ◽  
Xiaohong Zhang ◽  
Jingnan Liu ◽  
Xingxing Li ◽  
Xin Li
Keyword(s):  
Global Positioning System ◽  
Precise Point Positioning ◽  
Satellite System ◽  
Single Frequency ◽  
Long Period ◽  
Global Positioning ◽  
Low Costs ◽  
Point Positioning ◽  
Global Navigation Satellite ◽  
Globally Distributed

In view that most Global Navigation Satellite System (GNSS) users are still using single-frequency receivers due to the low costs, single-frequency Precise Point Positioning (PPP) has been attracting increasing attention in the GNSS community. For a long period, single-frequency PPP technology has mainly relied on the Global Positioning System (GPS). With the recent revitalisation of the Russian GLONASS constellation and two newly emerging constellations, BeiDou and Galileo, it is now feasible to investigate the performance of Four-Constellation integrated Single-Frequency PPP (FCSF-PPP) with GPS, GLONASS, BeiDou and Galileo measurements. In this study, a FCSF-PPP model is presented to simultaneously process observations from all four GNSS constellations. Datasets collected at 47 globally distributed four-system Multi-GNSS Experiment (MGEX) stations on seven consecutive days and a kinematic experimental dataset are employed to fully assess the performance of FCSF-PPP. The FCSF-PPP solutions are compared to GPS-only and combined GPS/GLONASS single-frequency PPP solutions. The results indicate that the positioning performance is significantly improved by integrating multi-constellation signals.

Maximum Ratio Principle-Based Estimation of Difference Inter-System Bias

2020 ◽  
Vol 73 (6) ◽  
pp. 1372-1386
Author(s):  
Zihan Peng ◽  
Chengfa Gao ◽  
Rui Shang
Keyword(s):  
Standard Deviation ◽  
Satellite System ◽  
Poor Quality ◽  
Combination Method ◽  
Quality Data ◽  
Complex Environments ◽  
Poor Quality Data ◽  
System Bias ◽  
Global Navigation Satellite ◽  
Principle Of Maximum

The tight combination model improves the positioning accuracy of the Global Navigation Satellite System (GNSS) in complex environments by increasing the redundancy of observation. However, the ambiguity cannot be calculated directly because of the correlation between it and the phase difference inter-system bias (DISB) in the model. This paper proposes a method of DISB estimation based on the principle of maximum ratio. From the data analysis, for the standard deviation of code DISB, the improvement of the method can up to 0·179 m with the poor quality data. In addition, compared to the parameter combination method, the standard deviation of all the phase DISB was deceased with the method in the paper. About the phase DISB of GPS L1/Galileo E1, the standard deviation decreased from 0·014/0·022/0·009/0·051 cycles to 0·006/0·015/0·004/0·029 cycles of four baselines, which represents the improvement of 57·14/31·82/55·56/43·14%. About the phase DISB of GPS L1/BDS B1, the standard deviation decreased from 0·014/0·061/0·010/0·052 cycles to 0·002/0·005/0·009/0·004 cycles of four baselines, which represents the improvement of 85·71/91·80/10·00/92·31%.

The characteristics of transforming coordinates from the geocentric system WGS-84 for the Mercator projection under low latitudes conditions

2018 ◽  
Vol 940 (10) ◽  
pp. 2-6
Author(s):  
J.A. Younes ◽  
M.G. Mustafin
Keyword(s):  
Coordinate System ◽  
Satellite System ◽  
Programming Algorithm ◽  
Low Latitude ◽  
Model Calculations ◽  
Mercator Projection ◽  
Low Latitudes ◽  
Rectangular Coordinates ◽  
Global Navigation Satellite ◽  
Coordination Methods

The issue of calculating the plane rectangular coordinates using the data obtained by the satellite observations during the creation of the geodetic networks is discussed in the article. The peculiarity of these works is in conversion of the coordinates into the Mercator projection, while the plane coordinate system on the base of Gauss-Kruger projection is used in Russia. When using the technology of global navigation satellite system, this task is relevant for any point (area) of the Earth due to a fundamentally different approach in determining the coordinates. The fact is that satellite determinations are much more precise than the ground coordination methods (triangulation and others). In addition, the conversion to the zonal coordinate system is associated with errors; the value at present can prove to be completely critical. The expediency of using the Mercator projection in the topographic and geodetic works production at low latitudes is shown numerically on the basis of model calculations. To convert the coordinates from the geocentric system with the Mercator projection, a programming algorithm which is widely used in Russia was chosen. For its application under low-latitude conditions, the modification of known formulas to be used in Saudi Arabia is implemented.

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