scholarly journals Radiointerferometric polar motion determination using a very long north-south baseline

1988 ◽  
Vol 128 ◽  
pp. 193-198 ◽  
Author(s):  
A Nothnagel ◽  
G. D. Nicolson ◽  
H Schuh ◽  
J Campbell ◽  
H Cloppenburg ◽  
...  
Keyword(s):  
Polar Motion ◽  
Daily Basis ◽  
Geodetic Survey ◽  
High Accuracy ◽  
National Geodetic Survey ◽  
Astronomy Observatory ◽  
Tectonic Plate ◽  
The Us ◽  
Single Baseline ◽  
Pole Component

The first high accuracy VLBI measurements with the Hartebeesthoek Radio Astronomy Observatory (HartRAO) at the southern end of the African tectonic plate were made possible at the beginning of 1986 through the loan of a MARK III DAT to HartRAO by the US National Geodetic Survey. Six twenty-four hour experiments spread over thirty-three days were used to precisely determine the HartRAO station position and to measure baseline lengths to Europe and North America. Interleaved between these multi-station experiments, a single baseline from Wettzell to HartRAO was used for two hours on a daily basis in order to measure pole positions. The formal errors of the x and y pole component determinations for each day are about ±2 mas and ±1 mas respectively, but an offset of about 6 mas from the IRIS values remains to be investigated.

Colorado geoid modeling at the US National Geodetic Survey

2020 ◽  
Vol 94 (10) ◽  
Author(s):  
Yan Ming Wang ◽  
Xiaopeng Li ◽  
Kevin Ahlgren ◽  
Jordan Krcmaric
Keyword(s):  
Geodetic Survey ◽  
National Geodetic Survey ◽  
The Us

scholarly journals An Improved Polar Motion and Earth Rotation Monitoring Service Using Radio Interferometry

1979 ◽  
Vol 82 ◽  
pp. 191-197 ◽  
Author(s):  
William E. Carter ◽  
Douglas S. Robertson ◽  
Michael D. Abell
Keyword(s):  
Earth Rotation ◽  
Polar Motion ◽  
Processing System ◽  
Geodetic Survey ◽  
National Geodetic Survey ◽  
Radio Interferometry ◽  
Station Network ◽  
Data Acquisition And Processing ◽  
Monitoring Service ◽  
New Generation

The National Geodetic Survey (NGS) of the National Ocean Survey (NOS), a component of the National Oceanic and Atmospheric Administration has begun a project to establish and operate a 3-station network of permanent observatories to monitor polar-motion and Earth rotation (UT1) by radio interferometric observations of quasars. The project designation is POLARIS (POLar-motion Analysis by Radio Interferometric Surveying).The POLARIS observatories will be equipped with a new generation of instrumentation and software, the Mark III data acquisition and processing system currently under development by a multi-organizational team.

Multi-GNSS Single-Difference Baseline Processing at NGS with newly developed M-PAGES software

2021 ◽  
Author(s):  
Bryan Stressler ◽  
Andria Bilich ◽  
Clement Ogaja ◽  
Jacob Heck
Keyword(s):  
Geodetic Survey ◽  
Integer Ambiguity ◽  
National Geodetic Survey ◽  
Processing Strategy ◽  
Dual Frequency ◽  
Software Suite ◽  
Legacy Software ◽  
Double Differences ◽  
Single Difference ◽  
Gps Observations

<p>The U.S. National Geodetic Survey (NGS) has historically processed dual-frequency GPS observations in a double-differenced mode using the legacy software called the Program for the Adjustment of GPS Ephemerides (PAGES). As part of NGS’ modernization efforts, a new software suite named M-PAGES (i.e., Multi-GNSS PAGES) is being developed to replace PAGES. M-PAGES consists of a suite of C++ and Python libraries, programs, and scripts built to process observations from all GNSS constellations. The M-PAGES team has developed a single-difference baseline processing strategy that is suitable for multi-GNSS. This approach avoids the difficulty of forming double-differences across systems or frequencies, which may inhibit integer ambiguity resolution. The M-PAGES suite is expected to deploy to NGS’ Online Positioning User Service (OPUS) later this year. Here, we present the processing strategy being implemented along with a performance evaluation from sample baseline solutions obtained from data collected within the NOAA CORS Network.</p>

A Method for the Evaluation of Vertical Crustal Movement from Scattered Geodetic Relevellings

1974 ◽  
Vol 11 (5) ◽  
pp. 605-610 ◽  
Author(s):  
P. Vaníček ◽  
D. Christodulidis
Keyword(s):  
Chesapeake Bay ◽  
Statistical Significance ◽  
Geodetic Survey ◽  
National Geodetic Survey ◽  
Specific Level ◽  
Vertical Crustal Movement ◽  
Crustal Movements ◽  
Velocity Surface ◽  
Vertical Crustal Movements ◽  
The U.S

The existing techniques for the quantitative evaluation of vertical crustal movements from geodetic spirit levelling have one common feature. They can deal only with a complete network of systematically relevelled connected lines. This paper presents a method, based on the least-squares fitting of a velocity surface, capable of using scattered as well as connected relevelled segments. A facility to choose a specific level of statistical significance of the results is built in. The performance of the method is tested on data for the vicinity of Chesapeake Bay. The results compare well with those of the U.S. National Geodetic Survey.

The experimental geoid 2020 – the first joint geoid model for the North American and Pacific Geopotential Datum 

2021 ◽  
Author(s):  
Yan Ming Wang ◽  
Xiaopeng Li ◽  
Kevin Ahlgren ◽  
Jordan Krcmaric ◽  
Ryan Hardy ◽  
...  
Keyword(s):  
North American ◽  
Gravity Data ◽  
The United States ◽  
Geodetic Survey ◽  
Airborne Gravity ◽  
Data Sets ◽  
National Geodetic Survey ◽  
Geoid Model ◽  
Satellite Gravity ◽  
The North

<p>For the upcoming North American-Pacific Geopotential Datum of 2022, the National Geodetic Survey (NGS), the Canadian Geodetic Survey (CGS) and the National Institute of Statistics and Geography of Mexico (INEGI) computed the first joint experimental gravimetric geoid model (xGEOID) on 1’x1’ grids that covers a region bordered by latitude 0 to 85 degree, longitude 180 to 350 degree east. xGEOID20 models are computed using terrestrial gravity data, the latest satellite gravity model GOCO06S, altimetric gravity data DTU15, and an additional nine airborne gravity blocks of the GRAV-D project, for a total of 63 blocks. In addition, a digital elevation model in a 3” grid was produced by combining MERIT, TanDEM-X, and USGS-NED and used for the topographic/gravimetric reductions. The geoid models computed from the height anomalies (NGS) and from the Helmert-Stokes scheme (CGS) were combined using two different weighting schemes, then evaluated against the independent GPS/leveling data sets. The models perform in a very similar way, and the geoid comparisons with the most accurate Geoid Slope Validation Surveys (GSVS) from 2011, 2014 and 2017 indicate that the relative geoid accuracy could be around 1-2 cm baseline lengths up to 300 km for these GSVS lines in the United States. The xGEOID20 A/B models were selected from the combined models based on the validation results. The geoid accuracies were also estimated using the forward modeling.</p>

scholarly journals VLBI Measurements of Radio Source Positions at Three U.S. Stations

1981 ◽  
Vol 63 ◽  
pp. 329-336
Author(s):  
Shu-Hua Ye
Keyword(s):  
Radio Source ◽  
Radio Astronomy ◽  
Data Reduction ◽  
Geodetic Survey ◽  
Time Span ◽  
National Geodetic Survey ◽  
Owens Valley ◽  
Radio Observatory ◽  
The U.S

AbstractResults of VLBI measurement of 14 radio source positions at three U.S. stations during the MERIT short campaign is presented. Comparisons with other solutions are given, together with the comparisons between several radio source catalogues.During the MERIT short campaign, several observatories cooperated in VLBI measurements organized jointly by the U.S. National Geodetic Survey (NGS) and the National Aeronautics and Space Administration (NASA). There were two 7-day observations arranged from Sept. 26 to Oct. 2 and from Oct. 16 to Oct. 22, with time span nearly 23 hours per day. Details of the observation and data reduction have been published elsewhere (1). This paper deals with radio source positions determined by three U.S. stations, the Haystack Observatory, the Harvard Radio Astronomy Station (HRAS) and the Owens Valley Radio Observatory (OVRO).

scholarly journals Some Considerations in the Use of Very-Long-Baseline-Interferometry to Establish Reference Coordinate Systems for Geodynamics

1980 ◽  
Vol 56 ◽  
pp. 205-216
Author(s):  
Douglas S. Robertson
Keyword(s):  
Reference Frames ◽  
Geodetic Survey ◽  
Limiting Factors ◽  
Radio Sources ◽  
National Geodetic Survey ◽  
Terrestrial Reference Frames ◽  
Long Baseline ◽  
Lithospheric Plates ◽  
Long Time ◽  
The Stability

AbstractPresent knowledge of the number, distribution, proper motion and structures of extragalactic radio sources indicates that there should be no problem in defining a celestial reference frame with stabilities of a few milliseconds of arc over time spans of the order of a decade. One of the limiting factors appears to be the structure of the sources. By measuring and monitoring these structures, the stability could probably be improved by as much as one or two orders of magnitude. Even without this improvement, a network of properly distributed fixed observatories making regular interferometric observations of these radio sources could be used to define a terrestrial coordinate system that could be maintained at the few centimeter level over indefinitely long time periods. Such a stable terrestrial reference system would be useful for a host of modern geodetic and geodynamic applications, including, in particular, studies of the time varying deformations and relative motions of lithospheric plates. The National Geodetic Survey has already begun work on a three station base network of permanent observatories under project POLARIS as a first step toward implementing the new celestial and terrestrial reference frames. It is hoped that others will join in the effort and make the new reference frames a reality by the middle of this decade.

scholarly journals Variability and Performance of Short to Long-Range Single Baseline RTK GNSS Positioning in Indonesia

2019 ◽  
Vol 94 ◽  
pp. 01012 ◽  
Author(s):  
Irwan Gumilar ◽  
Brian Bramanto ◽  
Fuad F. Rahman ◽  
I Made D. A. Hermawan
Keyword(s):  
Long Range ◽  
High Frequency ◽  
Carrier Phase ◽  
Satellite System ◽  
High Accuracy ◽  
Gnss Positioning ◽  
And Performance ◽  
Gnss Network ◽  
Single Baseline ◽  
Global Navigation Satellite

As the modernized Global Navigation Satellite System (GNSS) method, Real Time Kinematic (RTK) ensures high accuracy of position (within several centimeters). This method uses Ultra High Frequency (UHF) radio to transmit the correction data, however, due to gain and power issues, Networked Transport of RTCM via Internet Protocol (RTCM) is used to transmit the correction data for a longer baseline. This Research aims to investigate the performance of short to long-range single baseline RTK GNSS (Up to 80 KM) by applying modified LAMBDA method to resolve the ambiguity in carrier phase. The RTK solution then compared with the differential GNSS network solution. The results indicate that the differences are within RTK accuracy up to 80 km are several centimeter for horizontal solution and three times higher for vertical solution.

scholarly journals Tidal Datums with Spatially Varying Uncertainty in North-East Gulf of Mexico for VDatum Application

2018 ◽  
Vol 6 (4) ◽  
pp. 114 ◽  
Author(s):  
Liujuan Tang ◽  
Edward Myers ◽  
Lei Shi ◽  
Kurt Hess ◽  
Alison Carisio ◽  
...  
Keyword(s):  
Gulf Of Mexico ◽  
Measurement Errors ◽  
Deep Ocean ◽  
Geodetic Survey ◽  
National Geodetic Survey ◽  
Model Errors ◽  
Large Uncertainty ◽  
North East ◽  
The North ◽  
Spatially Varying

We conducted a VDatum-spatially varying uncertainty study for the North-East Gulf of Mexico. The newly developed tide model incorporated the latest available National Ocean Service (NOS) bathymetry survey data and National Geodetic Survey (NGS) shoreline data, and the datum products reflected the updated tidal datum data from the Center for Operational Oceanographic Products and Services (CO-OPS). A gridding technique based on the wavelength of long waves in the deep ocean was applied to improve model efficiency. In this study, we highlight the creation of the tidal datum products and associated spatially varying uncertainty, which was developed by blending the model results, observations, and measurement errors together using a spatially varying uncertainty method based on a variational approach. The study found that model errors, measurement errors, and lack of observations can contribute to large uncertainty in the tidal datum products. The need for high quality bathymetry data in coastal areas is essential for reducing model error. As for the large uncertainty due to lack of observations or large measurement error, this can be improved by placement of new observations with high precision. Compared to a single uncertainty value, the spatially varying uncertainty provides more accurate representation of the uncertainty for the tidal datum products in VDatum. The uncertainty results will be used to help with decision-making on placement of new tide gauges to further reduce the uncertainty in the VDatum products.

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