Migrating from ATS77 to NAD83(CSRS) in Nova Scotia

GEOMATICA ◽  
2017 ◽  
Vol 71 (2) ◽  
pp. 75-87
Author(s):  
Jason Bond
Keyword(s):  
Nova Scotia ◽  
Global Navigation Satellite Systems ◽  
Transformation Model ◽  
Mapping Data ◽  
Satellite Systems ◽  
Spatial Reference ◽  
The North ◽  
Coordinate Control ◽  
Original Size ◽  
Global Navigation Satellite

Since the late 1970s, the foundation for all survey work in Nova Scotia has been the Nova Scotia Coordinate Control System (NSCCS), which is based upon the Average Terrestrial System of 1977 (ATS77). In the early 2000s, some provincial mapping layers were migrated to the North American Datum of 1983 (based upon the Canadian Spatial Reference System (NAD83(CSRS)), but many still utilize ATS77. In 2012, the province began modernizing its Coordinate Referencing program using Global Navigation Satellite Systems (GNSS) and imple menting Active Control Stations (ACSs). The installation of 40 ACSs across the province between 2012 and 2015 enables the surveying community in Nova Scotia to migrate to NAD83(CSRS) by addressing ongoing accuracy and accessibility needs. The tech nology has allowed the passive, NAD83(CSRS)-based, Nova Scotia High Precision Network to expand to more than five times its original size. This densification effort has also allowed the transformation model between the two datums to be enhanced. With the geodetic infrastructure in place, the current primary need is for knowledge and methodologies to facilitate the transition. Two options are presented to aid surveyors and mappers in migrating data from ATS77 to NAD83(CSRS). The first approach utilizes a newly developed grid shift file intended for transforming mapping data and aiding surveyors in relocating boundary evidence, so that it can then be remeasured in NAD83(CSRS). A detailed discussion is provided on the development of grid shift file. The second approach is based upon the derivation of a set of local transformation parameters using a one-to-one sampling of the control monuments used in the historic survey.

scholarly journals Assessment of Empirical Troposphere Model GPT3 Based on NGL’s Global Troposphere Products

Sensors ◽  
2020 ◽  
Vol 20 (13) ◽  
pp. 3631
Author(s):  
Junsheng Ding ◽  
Junping Chen
Keyword(s):  
Global Navigation Satellite Systems ◽  
Tropospheric Delay ◽  
Strongly Correlated ◽  
International Gnss Service ◽  
Total Delay ◽  
Average Deviation ◽  
Satellite Systems ◽  
Global Average ◽  
The North ◽  
Global Navigation Satellite

Tropospheric delay is one of the major error sources in GNSS (Global Navigation Satellite Systems) positioning. Over the years, many approaches have been devised which aim at accurately modeling tropospheric delays, so-called troposphere models. Using the troposphere data of over 16,000 global stations in the last 10 years, as calculated by the Nevada Geodetic Laboratory (NGL), this paper evaluates the performance of the empirical troposphere model GPT3, which is the latest version of the GPT (Global Pressure and Temperature) series model. Owing to the large station number, long time-span and diverse station distribution, the spatiotemporal properties of the empirical model were analyzed using the average deviation (BIAS) and root mean square (RMS) error as indicators. The experimental results demonstrate that: (1) the troposphere products of NGL have the same accuracy as the IGS (International GNSS Service) products and can be used as a reference for evaluating general troposphere models. (2) The global average BIAS of the ZTD (zenith total delay) estimated by GPT3 is −0.99 cm and the global average RMS is 4.41 cm. The accuracy of the model is strongly correlated with latitude and ellipsoidal height, showing obviously seasonal variations. (3) The global average RMS of the north gradient and east gradient estimated by GPT3 is 0.77 mm and 0.73 mm, respectively, which are strongly correlated with each other, with values increasing from the equator to lower latitudes and decreasing from lower to higher latitudes.

scholarly journals The contribution of engineering surveys by means of GPS to the determination of crustal movements in Istanbul

2011 ◽  
Vol 11 (6) ◽  
pp. 1705-1713 ◽  
Author(s):  
M. Özyaşar ◽  
M. T. Özlüdemir
Keyword(s):  
Positional Information ◽  
Global Navigation Satellite Systems ◽  
Marmara Region ◽  
Satellite Systems ◽  
Geodetic Networks ◽  
The North ◽  
Richter Scale ◽  
Tectonically Active ◽  
Vertical Displacements ◽  
Global Navigation Satellite

Abstract. Global Navigation Satellite Systems (GNSS) are space based positioning techniques and widely used in geodetic applications. Geodetic networking accomplished by engineering surveys constitutes one of these tasks. Geodetic networks are used as the base of all kinds of geodetic implementations, Co from the cadastral plans to the relevant surveying processes during the realization of engineering applications. Geodetic networks consist of control points positioned in a defined reference frame. In fact, such positional information could be useful for other studies as well. One of such fields is geodynamic studies that use the changes of positions of control stations within a network in a certain time period to understand the characteristics of tectonic movements. In Turkey, which is located in tectonically active zones and struck by major earthquakes quite frequently, the positional information obtained in engineering surveys could be very useful for earthquake related studies. For this purpose, a GPS (Global Positioning System) network of 650 stations distributed over Istanbul (Istanbul GPS Triangulation Network; abbreviated IGNA) covering the northern part of the North Anatolian Fault Zone (NAFZ) was established in 1997 and measured in 1999. From 1998 to 2004, the IGNA network was extended to 1888 stations covering an area of about 6000 km2, the whole administration area of Istanbul. All 1888 stations within the IGNA network were remeasured in 2005. In these two campaigns there existed 452 common points, and between these two campaigns two major earthquakes took place, on 17 August and 12 November 1999 with a Richter scale magnitude of 7.4 and 7.2, respectively. Several studies conducted for estimating the horizontal and vertical displacements as a result of these earthquakes on NAFZ are discussed in this paper. In geodynamic projects carried out before the earthquakes in 1999, an annual average velocity of 2–2.5 cm for the stations along the NAFZ were estimated. Studies carried out using GPS observations in the same area after these earthquakes indicated that point displacements vary depending on their distance to the epicentres of the earthquakes. But the directions of point displacements are similar. The results obtained through the analysis of the IGNA network also show that there is a common trend in the directions of point displacements in the study area. In this paper, the past studies about the tectonics of Marmara region are summarised and the results of the displacement analysis on the IGNA network are discussed.

scholarly journals Estimating Wave Direction by Using Terrestrial GNSS Reflectometry

2019 ◽  
Author(s):  
Jörg Reinking ◽  
Ole Roggenbuck ◽  
Gilad Even-Tzur
Keyword(s):  
Correlation Length ◽  
Signal To Noise Ratio ◽  
Simulated Data ◽  
Global Navigation Satellite Systems ◽  
Wave Direction ◽  
Satellite Systems ◽  
The North ◽  
Scattered Power ◽  
Length Changes ◽  
Global Navigation Satellite

The signal-to-noise ratio (SNR) data is part of the global navigation satellite systems (GNSS) observables. In a marine environment, the oscillation of the SNR data can be used to derive reflector heights. Since the attenuation of the SNR oscillation is related to the roughness of the sea surface, the significant wave height (SWH) of the water surface can be calculated from the analysis of the attenuation. The attenuation depends additionally on the relation between the coherent and the incoherent part of the scattered power. The latter is a function of the correlation length of the surface waves. Because the correlation length changes with respect to the direction of the line of sight relative to the wave direction, the attenuation must show an anisotropic characteristic. In this work, we present a method to derive the wave direction from the anisotropy of the attenuation of the SNR data. The method is investigated based on simulated data as well by the analysis of experimental data from a GNSS station in the North Sea.

Modernization of the Nova Scotia Coordinate Referencing System through Active Control Technology

GEOMATICA ◽  
2015 ◽  
Vol 69 (4) ◽  
pp. 419-431 ◽  
Author(s):  
Jason Bond
Keyword(s):  
Nova Scotia ◽  
Active Control ◽  
Business Case ◽  
Global Navigation Satellite Systems ◽  
Land Registration ◽  
Satellite Systems ◽  
Land Administration ◽  
Short Period ◽  
Global Navigation Satellite ◽  
The Cost

The Nova Scotia Coordinate Referencing System (NSCRS) is Nova Scotia's current framework for pro viding location-based information. The NSCRS is the foundation for the province's geographic data hold ings including the land administration system. It also enables various legislation, including the Land Registration Act, the Crown Lands Act and the Land Surveyors Act. Over the past several decades, there has been a steady decline in the state of the province's coordinate referencing infrastructure as the program's human and budgetary resources have been reduced. As a result, risks and inefficiencies associated with decaying infrastructure have increased. By 2010, it was becoming clear that action would be required to address these concerns as well as accuracy and accessibility challenges. In 2012, the province began developing a strategy to better execute its coordinate referencing program. At the core of the strategy were Global Navigation Satellite Systems (GNSS) and Active Control Stations (ACSs). By placing ACSs across the rovince, the surveying industry would gain access to real-time, cen time ter-level positioning. Additionally, significant economic opportunities would emerge with respect to machine automation in agriculture, construction and navigation industries. A test phase was conducted over 2013–2014 that provided the necessary business case information to pursue province-wide implementation. It was determined that 40 ACSs would be needed to provide Nova Scotia with access to high-accuracy GNSS positioning services. The efficiencies introduced by the tech nol o gy would easily pay for the cost of the system in a short period. Most importantly, the technology provided a viable method of maintaining NSCRS infrastructure going forward.

Slip Complementarity and Triggering between the Foreshock, Mainshock, and Afterslip of the 2019 Ridgecrest Rupture Sequence

2020 ◽  
Vol 110 (4) ◽  
pp. 1701-1715 ◽  
Author(s):  
Qiang Qiu ◽  
Sylvain Barbot ◽  
Teng Wang ◽  
Shengji Wei
Keyword(s):  
Joint Inversion ◽  
Stress Transfer ◽  
Strong Motion ◽  
Global Navigation Satellite Systems ◽  
Fault System ◽  
Coseismic Slip ◽  
Satellite Systems ◽  
The North ◽  
Global Navigation Satellite ◽  
Lower Crustal

ABSTRACT We investigate the deformation processes during the 2019 Ridgecrest earthquake sequence by combining Global Navigation Satellite Systems, strong-motion, and Interferometric Synthetic Aperture Radar datasets in a joint inversion. The spatial complementarity of slip between the Mw 6.4 foreshock, Mw 7.1 mainshock, and afterslip suggests the importance of static stress transfer as a triggering mechanism during the rupture sequence. The coseismic slip of the foreshock concentrates mainly on the east-northeast–west-southwest fault above the hypocenter at depths of 2–8 km. The slip distribution of the mainshock straddles the region above the hypocenter with two isolated patches located to the north-northwest and south-southeast, respectively. The geodetically determined moment magnitudes of the foreshock and mainshock are equivalent to moment magnitudes Mw 6.4 and 7.0, assuming a rigidity of 30 GPa. We find a significant shallow slip deficit (>60%) in the Ridgecrest ruptures, likely resulting from the immature fault system in which the sequence occurred. Rapid afterslip concentrates at depths of 2–6 km, surrounding the rupture areas of the foreshock and mainshock. The ruptures also accelerated viscoelastic flow at lower-crustal depths. The Garlock fault was loaded at several locations, begging the question of possible delayed triggering.

scholarly journals Estimating Wave Direction Using Terrestrial GNSS Reflectometry

2019 ◽  
Vol 11 (9) ◽  
pp. 1027 ◽  
Author(s):  
Reinking ◽  
Roggenbuck ◽  
Even-Tzur
Keyword(s):  
Correlation Length ◽  
Signal To Noise Ratio ◽  
Simulated Data ◽  
Global Navigation Satellite Systems ◽  
Wave Direction ◽  
Satellite Systems ◽  
The North ◽  
Scattered Power ◽  
Length Changes ◽  
Global Navigation Satellite

The signal-to-noise ratio (SNR) data are part of the global navigation satellite systems (GNSS) observables. In a marine environment, the oscillation of the SNR data can be used to derive reflector heights. Since the attenuation of the SNR oscillation is related to the roughness of the sea surface, the significant wave height (SWH) of the water surface can be calculated from the analysis of the attenuation. The attenuation depends additionally on the relation between the coherent and the incoherent part of the scattered power. The latter is a function of the correlation length of the surface waves. Since the correlation length changes with respect to the direction of the line of sight relative to the wave direction, the attenuation must show an anisotropic characteristic. In this work, we present a method to derive the wave direction from the anisotropy of the attenuation of the SNR data. The method is investigated based on simulated data, as well by the analysis of experimental data from a GNSS station in the North Sea.

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