Integrated and Collaborative Organizations Create Geospatial Solutions Geospatial Solutions by DBZ Achieving Great Heights: Toward a Better Vertical Reference

Integrated and Collaborative Organizations Create Geospatial Solutions

Geospatial Solutions by DBZ

Achieving Great Heights: Toward a Better Vertical Reference System in Alaska

Michael Dennis, National Geodetic SurveyDavid B. Zilkoski, Geospatial Solutions by DBZ

March 28, 2014

Old Lines/New Datums48th Annual Alaska Surveying and Mapping Conference

Westmark Fairbanks Hotel and Conference CenterFairbanks, Alaska



Determining Reliable Orthometric Heights is Often Challenging But That Is Especially The Case In Alaska

Some of the Things That Make Alaska Such a Challenge Include:

• Sparseness and Age of the Geodetic Leveling Network

• Vertical Tectonic Movement

• Large Areas With No Road Access

• Lack of Terrestrial Gravity Data

• Poor Digital Models of Topography (Used for Gravitation Calculations)




• This Presentation Will Describe Some New and Future Developments Related to Height Determination in Alaska

• Condition of the existing NAVD 88 leveling network in Alaska

• The latest NGS scientific and hybrid geoid models (USGG2012 and GEOID12A)

• Bench marks used to develop GEOID12A

• Status of the Gravity for the Redefinition of the American Vertical Datum (GRAV-D) Project

• The new vertical datum planned for completion in 2022

• What is needed to meet future surveying and mapping requirements in Alaska

• Discuss How Alaskans Can Help NGS Make a Better, More Accurate Geoid Model




Condition of the existing NAVD 88 leveling network in Alaska















The latest NGS scientific and hybrid geoid models (USGG2012 and GEOID12A)


USGG2012 minus

GEOID12A (feet)

USGG2012 minus

GEOID12A (feet)



Above a LMSL Datum

Above a LMSL Datum

Analysis of GEOID12A






Rejected




Rejected









Total Post-1964 Postseismic Uplift

1964 to presentUnits: cm

Cohen and Freymueller (2004)



Status of the Gravity for the Redefinition of the American Vertical Datum (GRAV-D) Project


GRAV-D statusGRAV-D status



The new vertical datum planned for completion in 2022


NAD 83(2011) to NAD 83(2011) to IGS08 at epoch 2022.0IGS08 at epoch 2022.0

New vertical datum ortho height minus NAVD 88 (m)



New Leveling Observations

Better Knowledge of the Vertical Tectonic Movement

More Gravity Data

Better Digital Models of Topography


What is needed to meet future surveying and mapping requirements in Alaska

Prevent Earthquakes and Crustal Motion from

Occurring



Challenging But That Is Especially The Case In AlaskaDetermining Reliable Orthometric Heights is Often

How Alaskans can help NGS make a better, more accurate geoid model



• Obtain New Leveling Observations

• Obtain Better Knowledge of the Vertical Tectonic Movement

• Obtain More Gravity Data

• Obtain Better Digital Models of Topography

Challenging But That Is Especially The Case In AlaskaDetermining Reliable Orthometric Heights is Often


Educate Leaders and Visionaries about the Issues and Problems Associated

with Alaska’s Vertical Control Network



Challenging But That Is Especially The Case In Alaska

Determining Reliable Orthometric Heights is Often

• Provide New Leveling Data to NGS Using NGS Locus Tool

• Provide GPS Data on New Leveling Stations Using NGS OPUS-Projects Tool


Leveling Observations Along Entire Line

GPS Observations

GPS Observations

GPS Observations

GPS Observations

GPS Observations



Documents

Integrated and Collaborative Organizations Create Geospatial Solutions Geospatial Solutions by DBZ Achieving Great Heights: Toward a Better Vertical Reference