scholarly journals Getting the Height Right: The North American Vertical Datum of 1988

2020 ◽  
Vol 90 (9) ◽  
pp. 36-39
Author(s):  
T.R. Witcher
Keyword(s):  
North American ◽  
The North ◽  
Vertical Datum

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.

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.

1588: The Bicalutamide Early Prostate Cancer Program: Findings of the North American Trial at 7.7 Years' Median Follow-Up

2006 ◽  
Vol 175 (4S) ◽  
pp. 511-512
Author(s):  
David G. McLeod ◽  
Ira Klimberg ◽  
Donald Gleason ◽  
Gerald Chodak ◽  
Thomas Morris ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
North American ◽  
Early Prostate Cancer ◽  
The North ◽  
Cancer Program
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