Modernizing the Datums of the National Spatial Reference System

2015 ◽  
Vol 49 (2) ◽  
pp. 151-158
Author(s):  
Dru A. Smith ◽  
Daniel R. Roman ◽  
Vicki A. Childers
Keyword(s):  
North American ◽  
Reference System ◽  
Passive Control ◽  
The United States ◽  
Geodetic Survey ◽  
Federal Agencies ◽  
National Geodetic Survey ◽  
Spatial Reference ◽  
The North ◽  
Vertical Datum

AbstractThe National Spatial Reference System (NSRS) is the official coordinate system for all geospatial activities performed by civilian federal agencies of the United States, including National Oceanic and Atmospheric Administration's navigational charts. Two of the datums that make up the bulk of the NSRS, the North American Datum of 1983 (NAD 83) and the North American Vertical Datum of 1988 (NAVD 88), were created with the most accurate surveying technology available in the 1970s and 1980s. However, analysis over the last decade has proven that both datums contain systematic errors at the few meters level. While there have been improvements to these datums over the years, they have all been restricted to adjusting subsets of coordinates within the datum, rather than replacing the datum itself. However, the rise of near-real-time positioning technologies at the few centimeter level has made it no longer viable to maintain the two datums.The National Geodetic Survey is engaged in a decade-long effort to prepare the NSRS user community and collect the necessary data to define two new datums that will not only replace NAD 83 and NAVD 88 but also reduce the overall reliance of those two datums on passive control. The two new datums are expected to be completed and jointly released in 2022.

The north american vertical datum of 1988 (navd ‘88) internal status report prepared for cism ‘88 winnipeg, manitoba may 24-27, 1988

CISM journal ◽  
1989 ◽  
Vol 43 (4) ◽  
pp. 387-393
Author(s):  
Fred W. Young ◽  
John Murakami
Keyword(s):  
North American ◽  
The United States ◽  
Geodetic Survey ◽  
Background Information ◽  
Status Report ◽  
National Geodetic Survey ◽  
The North ◽  
Vertical Datum ◽  
History Of ◽  
Expected Benefits

Canada and the United States through their respective national geodetic survey organizations have been cooperating in a project to redefine the heights for bench marks in North America. This report will deal with a history of the levelling network in Canada, provide background information about the North American Vertical Datum of 1988 (NAVD ‘88) Project itself, give an update concerning key Canadian activities and tasks related to the project, and finally state the expected benefits of such an undertaking.

scholarly journals REPLACING NAVD88: THE EFFECTS OF VERTICAL DATUM MODERNIZATION ON COASTAL ENGINEERING

2018 ◽  
pp. 58
Author(s):  
Nicole Kinsman ◽  
Monica Youngman
Keyword(s):  
Mississippi River ◽  
North American ◽  
Vertical Motion ◽  
The United States ◽  
Satellite System ◽  
Geodetic Survey ◽  
National Geodetic Survey ◽  
Geoid Model ◽  
The North ◽  
Vertical Datum

The United States (US) National Geodetic Survey (NGS) will be replacing the North American Vertical Datum of 1988 (NAVD88) with the North American-Pacific Geopotential Datum of 2022 (NAPGD2022). NAVD88 is still the official vertical datum of the NSRS at this time, but it is in need of improvement; it is both biased (by about one-half meter) and tilted (about 1 meter coast to coast) relative to the best global geoid models available today. This issue stems from the fact that NAVD88 was defined primarily using terrestrial surveying techniques at passive geodetic survey marks. For access, users must often collect hours of Global Navigation Satellite System (GNSS) data, or rely on our nation’s network of passive survey marks, which is not fully stable (consider areas of subsidence such as the Mississippi River delta) and is deteriorating over time. Maintenance of these marks requires significant resources and vertical motion of marks is not tracked in a systematic way. A modernized vertical reference frame will primarily rely on GNSS such as the Global Positioning System (GPS) in combination with an updated and time-tracked geoid model. This paradigm shift will result in improvements to the National Spatial Reference System (NSRS) that will provide users with enhanced access, easier maintenance, and more consistent coordinates for precise positioning activities nationwide.

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>

The Impact of the Implementation of The North American Datum of 1983 (NAD 83) on Aeronautical Navigation in the United States

1993 ◽  
pp. 3-8
Author(s):  
Ronald M. Bolton
Keyword(s):  
United States ◽  
North American ◽  
Traffic Control ◽  
Reference System ◽  
New Technology ◽  
The United States ◽  
Geodetic Reference System ◽  
The North ◽  
Almost All ◽  
The Impact

On October 15, 1992, the horizontal geodetic reference system used for all aeronautical charts and chart-related products published by National Oceanic and Atmospheric Administration (NOAA)/National Ocean Service (NOS) changed from the North American Datum of 1927 (NAO 27) to the North American Datum of 1983 (NAO 83). The Global Positioning System (GPS) now allows satellites to define much more accurately geographic locations in terms of latitude and longitude, utilizing an earth centered reference system; the NAO 83 is based on this new technology. As a result, the latitude and longitude of almost all points in the National Airspace System (NAS) were revised. The greatest coordinate s hifts were in Hawaii and Alaska where latitude moved by as much as 1200 feet and longitude by up to 950 feet. In the conterminous U.S., the largest changes were approximately 165 feet in latitude and 345 feet in longitude. The impact to aeronautical navigation in the C.S. of the datum shift from NAO 27 to NAO 83 was not limited to aeronautical charts and related publications. All Flight Management Systems (FMSs) and Air Traffic Control Systems (ATCs) had to be modified to accept and utilize the NAO 83 coordinates. The impact of the implementation of NAO 83 on aeronautical navigation in the United States was s gnificant.

Development and evaluation of the xGEOID20 Digital Elevation Model at NGS

2020 ◽  
Author(s):  
Jordan Krcmaric
Keyword(s):  
Digital Elevation Model ◽  
Geoid Undulation ◽  
Geodetic Survey ◽  
National Geodetic Survey ◽  
Geoid Model ◽  
The North ◽  
Digital Elevation ◽  
Vertical Datum ◽  
Elevation Model ◽  
Ellipsoid Heights

<p>The U.S. National Geodetic Survey (NGS), an office of the National Oceanic and Atmospheric Administration (NOAA), will release a new vertical datum in 2022, the North American-Pacific Geopotential Datum of 2022 (NAPGD2022). This new datum will be based on a high degree spherical harmonic model of the Earth’s gravitational potential, and will yield a geoid undulation model (GEOID2022) to calculate orthometric heights from GNSS-derived ellipsoid heights.</p><p>In preparation for the new vertical datum, NGS has computed annual experimental geoid models (xGEOID) since 2014. This year’s xGEOID model (xGEOID20) will use an updated digital elevation model (DEM) composed of TanDEM-X, 3DEP, MERIT, and other DEMs. The DEMs are merged together to create a seamless elevation model across the extent of the xGEOID20 model. The accuracy of the merged DEM is tested using independent datasets such as GPS on benchmarks and Icesat-2. The effect of the updated DEM on the geoid model is also determined by comparing geoid models computed with previous DEMs to the new xGEOID20 model, and with comparisons to the NGS Geoid Slope Validation Survey lines.</p>

scholarly journals Progress in Diagnosing Primary Ciliary Dyskinesia: The North American Perspective

Diagnostics ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1278
Author(s):  
Michael Glenn O’Connor ◽  
Amjad Horani ◽  
Adam J. Shapiro
Keyword(s):  
Genetic Testing ◽  
North America ◽  
North American ◽  
Primary Ciliary Dyskinesia ◽  
Clinical Phenotype ◽  
The United States ◽  
Diagnostic Process ◽  
The North ◽  
Diagnostic Guideline ◽  
Ciliary Dyskinesia

Primary Ciliary Dyskinesia (PCD) is a rare, under-recognized disease that affects respiratory ciliary function, resulting in chronic oto-sino-pulmonary disease. The PCD clinical phenotype overlaps with other common respiratory conditions and no single diagnostic test detects all forms of PCD. In 2018, PCD experts collaborated with the American Thoracic Society (ATS) to create a clinical diagnostic guideline for patients across North America, specifically considering the local resources and limitations for PCD diagnosis in the United States and Canada. Nasal nitric oxide (nNO) testing is recommended for first-line testing in patients ≥5 years old with a compatible clinical phenotype; however, all low nNO values require confirmation with genetic testing or ciliary electron micrograph (EM) analysis. Furthermore, these guidelines recognize that not all North American patients have access to nNO testing and isolated genetic testing is appropriate in cases with strong clinical PCD phenotypes. For unresolved diagnostic cases, referral to a PCD Foundation accredited center is recommended. The purpose of this narrative review is to provide insight on the North American PCD diagnostic process, to enhance the understanding of and adherence to current guidelines, and to promote collaboration with diagnostic pathways used outside of North America.

scholarly journals “The Future of Archaeology Is Antiracist”: Archaeology in the Time of Black Lives Matter

2021 ◽  
pp. 1-20
Author(s):  
Ayana Omilade Flewellen ◽  
Justin P. Dunnavant ◽  
Alicia Odewale ◽  
Alexandra Jones ◽  
Tsione Wolde-Michael ◽  
...  
Keyword(s):  
United States ◽  
North American ◽  
The United States ◽  
Heritage Preservation ◽  
Social Unrest ◽  
Black Lives Matter ◽  
The North ◽  
Road Map ◽  
The Social ◽  
The Future

This forum builds on the discussion stimulated during an online salon in which the authors participated on June 25, 2020, entitled “Archaeology in the Time of Black Lives Matter,” and which was cosponsored by the Society of Black Archaeologists (SBA), the North American Theoretical Archaeology Group (TAG), and the Columbia Center for Archaeology. The online salon reflected on the social unrest that gripped the United States in the spring of 2020, gauged the history and conditions leading up to it, and considered its rippling throughout the disciplines of archaeology and heritage preservation. Within the forum, the authors go beyond reporting the generative conversation that took place in June by presenting a road map for an antiracist archaeology in which antiblackness is dismantled.

A SYNOPSIS OF THE NORTH AMERICAN SPECIES OF SYNDIPNUS (HYMEN., ICHNEUMONIDAE)

1940 ◽  
Vol 72 (7) ◽  
pp. 135-145 ◽  
Author(s):  
G. Stuart Walley
Keyword(s):  
United States ◽  
North American ◽  
The United States ◽  
North American Species ◽  
National Museum ◽  
United States National Museum ◽  
The North

As noted below the two North American species described in Syndipnus by workers appear to belong in other genrra. In Europe the gunus is represented by nearly a score of species and has been reviewed in recent years by two writers (1, 2). North American collections contain very few representatives of the genus; after combining the material in the National Collection with that from the United States National Museum, the latter kindly loaned to me by Mr. R. A. Cushman, only thirty-seven specimens are available for study.

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