# Presentation: 701028

## National Hydrologic Program Managers ConferenceVertical Datum Initiative: NOAA’s Height Modernization ProgramJuly 12, 2007National Geodetic Survey

- Renee Shields
- National Geodetic Survey
- National Oceanic and Atmospheric Administration

## Overview

- What NGS does
- Why are heights important
- Datums
- Height Modernization

## Overview

## Slide 4

## Mission of NGS

- To define, maintain and provide access to the **National Spatial Reference System** to meet our nation’s economic, social, and environmental needs
- and
- To be a **world leader** in geospatial activities, including the development and promotion of **standards, specifications, and guidelines**.

**http://geodesy.noaa.gov/INFO/ngs_tenyearplan.pdf**

## Define the NSRS
“The NSRS must be more accurate than all activities which build upon it, while still being practicably achievable.”

Maintain the NSRS
“NGS must track all of the temporal changes to the defining points of the NSRS in such a way as to always maintain the accuracy in the NSRS definition.”

Provide Access to the NSRS
“NGS must develop and maintain guidelines for users to access the NSRS at a variety of accuracies.”
“NGS will publish all coordinates of defining points of the NSRS with an epoch tag and will furthermore publish velocities relative to that epoch-tagged set of coordinates”

- “The NSRS must be _*more accurate*_ than all activities which build upon it, while still being practicably achievable.”
**Maintain the NSRS**
- “NGS must _*track all of the temporal changes*_ to the defining points of the NSRS in such a way as to always maintain the accuracy in the NSRS definition.”
**Provide Access to the NSRS**
- “NGS must develop and maintain guidelines for users to access the NSRS at _*a variety of accuracies*_.”
- “NGS will publish _*all coordinates*_ of defining points of the NSRS _*with an epoch tag and*_ will furthermore publish _*velocities*_ relative to that epoch-tagged set of coordinates”

**Planning at NGS**

**http://geodesy.noaa.gov/INFO/ngs_tenyearplan.pdf**

**From the NGS 10-Year Plan**

## The official national coordinate system of the U.S. federal government which includes:
Geodetic latitude, longitude and height
Scale, gravity, and orientation
How these values change with time

Components include:
National and Cooperative CORS
Network of passive monuments
Official national shoreline 
Precise orbits of GNSS satellites used to define NSRS
Models and tools to describe how all of these quantities change over time.

- Geodetic latitude, longitude and height
- Scale, gravity, and orientation
**How these values change with time**
**Components include:**
- National and Cooperative CORS
- Network of passive monuments
- Official national shoreline
- Precise orbits of GNSS satellites used to define NSRS
- Models and tools to describe how all of these quantities change over time.

**Mission – The NSRS is...**

## Coastal hazards / flooding
Coastal uplands / ecosystem management
Hydrography
Shoreline mapping
Storm and tsunami modeling
Coastal erosion
Benthic habitats

- Coastal uplands / ecosystem management
- Hydrography
- Shoreline mapping
- Storm and tsunami modeling
- Coastal erosion
- Benthic habitats

- NOAA Applications of Elevation

## Local Issues

**Local Issues**

## What is a GEODETIC DATUM?

- A set of constants specifying the coordinate system used for geodetic control, i.e., for calculating coordinates of points on the Earth*
- [above] together with the coordinate system and the set of all points and lines whose coordinates, lengths, and directions have been determined by measurement or calculation.*
-                      *Definitions from the Geodetic Glossary, September 1986

**Notes:**
Understanding what a datum is will help in understanding where the heights come from and the differences between the heights.
At NGS we use the second definition – note that the 2nd definition does not include the actual computed coordinates.  If it did, then if the coordinates changed, the name of the datum would have to change.   For example, because of GPS technology and the ability to compute better and better positions, the original NAD83 (86) coordinates across the country have been superceded by coordinates recomputed using CORS and High Accuracy Reference Networks as control.  NGS devised a way to distinguish the original coordinates from the superceded coordinates with the use of a ‘datum tag,’ labeling the datum with the year the coordinates were computed.  But the datum remained NAD83.

## Not To Be Confused With:

- Ellipsoid
- A closed surface, whose planar sections are either ellipsoids or circles.*
- Mathematical figure which helps define a Reference Frame
- Clarke 1866, GRS80
- Reference Frame
- A coordinate system associated with a physical system.*
- NSRS, ITRF
-      *Definitions from the Geodetic Glossary, September 1986

**Notes:**
Ellipsoid isn’t the datum - it is part of the definition of a datum.
You need a mathematical figure on which to do computations.  The earth is not a uniform shape, so we need something to approximate the shape and size of the earth.  The ellipsoid helps define the scale needed in your definition of a datum.  
The reference frame gives you the means to define the orientation of the system.
Together, these can define the datum.  At NGS, we add the points and observations so they are included in the definition.

## Horizontal Control Datum?

- A Geodetic Datum specifying the coordinate system in which horizontal control points are located.*
- Defined by 8 Constants
- 3 define location of the origin of the coordinate system.
- 3 define orientation of the coordinate system.
- 2 define dimensions of the reference ellipsoid.
- WGS84, GUAM63, NAD 27, NAD 83
-                                                                                                     *Definition from the Geodetic Glossary, September 1986

**Notes:**
Horizontal datum is defined as a 3-dimensional datum because of earth centered ellipsoid.

This came about when NAD83 was done because Doppler and VLBI observations were used to orient the ellipsoid.  Also, gravity has an effect on some observations, so curvature of the earth has to be taken into account.

## 
                                                       		    NAD 27                      NAD 83

ELLIPSOID          CLARKE 1866	    	      GRS80
       a = 6,378,206.4 M                    a = 6,378,137.0 M
       1/f = 294.9786982                   1/f = 298.257222101

DATUM POINT    Triangulation Station                 NONE
       MEADES RANCH, Kansas           EARTH MASS CENTER

ADJUSTMENT      25k STATIONS                         250k STATIONS
    Several Hundred Base Lines         Approx. 30k EDMI Base Lines
    Several Hundred Astro Azimuths   5k Astro Azimuths
                                                      Doppler Point Positions
                                                      VLBI Vectors

BEST FITTING      North America                         World-Wide

-                                                        		    _**NAD 27**_**                      **_**NAD 83**_
**ELLIPSOID**          CLARKE 1866	    	      GRS80
-        a = 6,378,206.4 M                    a = 6,378,137.0 M
-        1/f = 294.9786982                   1/f = 298.257222101
**DATUM POINT**    Triangulation Station                 NONE
-        MEADES RANCH, Kansas           EARTH MASS CENTER
**ADJUSTMENT**      25k STATIONS                         250k STATIONS
-     Several Hundred Base Lines         Approx. 30k EDMI Base Lines
-     Several Hundred Astro Azimuths   5k Astro Azimuths
-                                                       Doppler Point Positions
-                                                       VLBI Vectors
**BEST FITTING**      North America                         World-Wide

**Compare Horizontal Datum Elements**

**Notes:**
This shows the components of the NAD 27 and NAD 83 datums.

## NAD 27 and NAD 83

**NAD 27 and NAD 83**

**Notes:**
Up to 100 meter shift – in Alaska

## Vertical Control Datum?

- “A Geodetic Datum specifying the system in which vertical control points are located.” *
- A set of fundamental elevations to which other elevations are referred
- NGVD 29, NAVD 88, IGLD85, PR2002
- Others – Cairo, Local
- Tidal – MLLW, MLW, MHW, MHHW
-           *Definitions from the Geodetic Glossary, September 1986

**Notes:**
NGVD29 was originally called the Mean Sea Level Datum of 1929 
Changed to National Geodetic Vertical Datum of 1929
	- NGVD 29, July 2, 1973 Federal Register notice

## NAVD 88

**North American Vertical Datum of 1988**

**Federal Register / Vol. 58, No. 120**
**SUMMARY: This Notice announces a decision by the Federal Geodetic Control Subcommittee (FGCS) to affirm the North American Vertical Datum of 1988 (**_**NAVD 88**_**) as the **_**official civilian vertical datum for surveying and mapping**_** activities in the United States performed or financed by the Federal Government, and to the extent practicable, legally allowable, and feasible, require that **_**all Federal agencies using or producing vertical height information undertake an orderly transition to NAVD 88**_**.**

***	***- NAVD 88, June 24, 1993

## 
                            NGVD 29                             NAVD 88

DATUM DEFINITION      26  Tide Gauges                    FATHER’S POINT/Rimouski 
                            in the U.S. & Canada                       Quebec,  Canada

GEOID FITTING      Distorted to Fit MSL Gauges                 Best Continental Model

CORRECTIONS	       Normal Gravity, Level, 	          Observed Gravity, Level, 
                                          Rod, Temp.		 Rod, Temp. Magnetic, Refraction 

BENCH MARKS       	 100,000                                          450,000 

LEVELING (Km)         106,724 (U.S. + Canada)                         1,001,500 

**                            **_**NGVD 29**_**                             **_**NAVD 88**_
**DATUM DEFINITION**      26  Tide Gauges                    FATHER’S POINT/Rimouski
-                             in the U.S. & Canada                       Quebec,  Canada
**GEOID FITTING**      Distorted to Fit MSL Gauges                 Best Continental Model
**CORRECTIONS**	       Normal Gravity, Level, 	          Observed Gravity, Level,
-                                           Rod, Temp.		 Rod, Temp. Magnetic, Refraction
**BENCH MARKS**       	 100,000                                          450,000
**LEVELING (Km)**         106,724 (U.S. + Canada)                         1,001,500

**Vertical Datum Elements: NGVD29 vs NAVD88**

**Notes:**
This shows the differences in the components of the vertical datums.

The datum is not just the values, but the way the computations are done.  For the 1929, normal gravity was used to correct the orthometric height, for 1988 actual gravity was used and geopotential nos were computed.  For 1929 only level, Rod and temp corrections were applied, for 1988 we also used astronomic, magnetic, and refraction corrections.
Only one point was constrained in the NAVD 88 adjustment because it had been demonstrated that there were variations in sea surface topography, that mean sea level at different tide gauges is not the same equipotential surface.

## Differential Leveling – NGVD29

**Differential Leveling – NGVD29**

## Differential Leveling – NAVD88

**Differential Leveling – NAVD88**

## Height Difference - NGVD29 to NAVD88

**0**

**0**

**Height Difference - NGVD29 to NAVD88**

- NOAA/NGS

## Slide 22

**Notes:**
National color map - differences between NGVD29 and NAVD88 datums

Portrays general east - west tilt; rugged areas indicate major changes whereas smooth are minor changes. 2 & 3 cm level differences over steep gradients.

## Summary - Datum Basics

- Geospatial positioning must be referenced to a common *datum*
- A geodetic horizontal or 3-dimensional datum is defined by 8 constants that define an ellipsoid (2), a coordinate system (3), and an orientation (3)
- A geodetic vertical datum is a set of fundamental elevations to which other elevations are referred

**Notes:**
Ellipsoid isn’t the datum - it is part of the definition of a datum.
You need a mathematical figure on which to do computations.  The earth is not a uniform shape, so we need something to approximate the shape and size of the earth.  The ellipsoid helps define the scale needed in your definition of a datum.  
The reference frame gives you the means to define the orientation of the system.
Together, these can define the datum.  At NGS, we add the points and observations so they are included in the definition.

## Datum Basics

- The legal National geodetic horizontal (3D) datum is NAD 83
- The legal National geodetic vertical datum is the NAVD 88
- Datums change if there are changes in circumstances, need, or technology
- It is important to identify and label the datum that positions are related to – *metadata*
_*Never mix datums*_*!*

## One Position, Different Datums

## What types of heights are involved?
Orthometric heights
Ellipsoid heights
Geoid heights

How are these heights defined and related?

How accurately can these heights be determined?

- Orthometric heights
- Ellipsoid heights
- Geoid heights
- How are these heights defined and related?
- How accurately can these heights be determined?

**How to achieve accurate heights**

**Notes:**
Need to understand the three different heights to fully understand GPS derived orthometric heights.

Heights & Datums  - traditionally orthometric heights meant above sea level.  

You need to be aware of the limitations of each height system to understand what you get when using GPS to determine heights.

**(NAVD88)**** H**

**H = Orthometric Height**  **(leveling)**

**H** ** = ****h**** - ****N**

- TOPOGRAPHIC SURFACE

**h = Ellipsoidal Height (GPS)**

**N = Geoid Height (model)**

**H ****(NAD83)**

- Ellipsoid

**N**

-   Geoid

- Geoid *Height*
-   **(GEOID03)**

**Ellipsoid, Geoid, ****and Orthometric Heights**

**Notes:**
Orthometric height is the height on the surface above the geoid.  But we can’t measure from the geoid so we use leveling. The NAVD88 is defined from the control point, B, in Quebec.  Because the ortho ht at A is computed from leveling observations, where error is modeled or estimated, it probably isn’t right at the geoid, right at “sea level”.

Our vertical datum is defined.  We need a geoid that we can use that is relative to the vertical datum. 

Note that in this picture the geoid is shown above the ellipsoid.  In the continental United States, the geoid is actually below the ellipsoid, so the value of the geoid height is negative.

## “H” - Conventional Leveling

**“****H” - Conventional Leveling**

## GEOIDS versus GEOID HEIGHTS

- “The *equipotential surface* of the Earth’s gravity field which best fits, in the least squares sense, (global) mean sea level.”*
- Can’t see the surface or measure it directly.
- Can be modeled from gravity data as they are mathematically related.
- Note that the geoid is a vertical *datum* surface.
- A geoid *height* is the height from an ellipsoidal datum to a geoid.
- Hence, geoid height models are directly tied to the geoid and ellipsoid that define them (i.e., geoid height models are _not_ interchangeable).
-    		*Definition from the Geodetic Glossary, September 1986

**Notes:**
-What does equipotential surface mean? 
-If we could see or measure the geoid, this could be our vertical datum.  
-It may be in the future, and we must plan for a transition.
-For now, we are dependant on leveling observations on the surface to create our datum. 
-The leveling datum may or may not be a true equipotential surface (i.e., NAVD 88 =/ true geoid).
-use the geoid height models to transform between the ellipsoidal and vertical datums.

## In Search of the Geoid...

**In Search of the Geoid...**

**Courtesy of Natural Resources Canada**  www.geod.nrcan.gc.ca/index_e/geodesy_e/geoid03_e.html

- Dr. Dan Roman

**Notes:**
-The geoid extends everywhere and provides a common datum for all.

## Earth Gravity Model of 1996 (EGM96)
2.6 million terrestrial, ship-borne, and altimetric gravity measurements
offshore altimetry from GSFC.001 instead of KMS98
30 arc second Digital Elevation Data
3 arc second DEM for the Northwest USA
Decimated from 1 arc second NGSDEM99
Computed on 1 x 1 arc minute grid spacing
GRS-80 ellipsoid centered at ITRF00 origin

**2.6 million terrestrial, ship-borne, and altimetric gravity measurements**
**offshore altimetry from GSFC.001 instead of KMS98**
**30 arc second Digital Elevation Data**
**3 arc second DEM for the Northwest USA**
**Decimated from 1 arc second NGSDEM99**
**Computed on 1 x 1 arc minute grid spacing**
**GRS-80 ellipsoid centered at ITRF00 origin**

**High Resolution Geoid Models****USGG2003 (Scientific Model)**

**Notes:**
- G99SSS (scientific model) - determined from 2.6 million gravity measurements taken over the last century and stored in NGS database.  Major improvements over previous models; more data.
- 30 arc second, 1 km x 1 km, grid of digital elevation data; with updated Canadian Rockies data from G96SSS.
- 3 arc second DEM - northwestern portion of U.S. which has history of poor geoid interpretation.
- EGM96 (Earth Gravity Model of 1996) developed by National Imaging and Mapping Agency (NIMA) - global model of gravity and geoid undulations; good in large areas but not as good for smaller areas.
- 1-D spherical Stokes’ FFT (Fast Fourier Transformation) - “remove-compute-restore” (fix and put back into model - iterative process).

Final outcome - 1 x 1 arc minute spacing interpolation of the geoid model; 2' x 2' in Alaska.  1 arc minute equals about 1.8 km on ground.
ITRF97 (1997.0) COM (Center Of Mass) based origin for model.

## Gravity Coverage for GEOID03

**Notes:**
This shows the extent of the gravity data that went info the USGG2003 geoid model.
Terrestrial data onshore; shipborne and altimetric data offshore.

## Slide 33

**Notes:**
-although GSFC00.1 created significant changes (50 cm or more in some regions when looking at the difference between G99SSS and USGG2003, the magnitude of those differences is dwarfed by the total signal

This model is tied to a GRS-80 ellipsoid centered at ITRF00 and the Wo value of EGM96 ... but that isn’t what we need to use it with level data.

## High Resolution Geoid ModelsGEOID03 (vs. Geoid99)

**Begin with USGG2003 model **
**14,185**** NAD83 GPS heights on NAVD88 leveled benchmarks (vs. 6169)**
**Determine national bias and trend relative to GPS/BMs**
**Create grid to model local (state-wide) remaining differences**
**ITRF00****/NAD83 transformation (vs. ITRF97)**

**Notes:**
GEOID03 - best model for North America; not a true interpretation of the geoid but includes bias to establish best orthometric heights relative to NAVD88.

14,185 GPS/levels bench marks (NAD83/NAVD88); more to be included to further improve future models.  GPS/BM constrained to help model reflect NAVD88 orthometric heights then unconstrained for final model.

## High Resolution Geoid ModelsGEOID03 (vs. Geoid99)

**Compute and remove conversion surface from USGG2003 **
**Relative to non-geocentric GRS-80 ellipsoid **
**2.7**** cm RMS nationally when compared to BM data (vs. 4.6 cm)**
**RMS ******** ****50%**** improvement over GEOID99 (Geoid96 to 99 was 16%)**

**Notes:**
-NAD83 non-COM - model warped to reflect NAD83 (86) non-COM origin.
-2.7 cm RMS when comparing to bench mark data – includes 2 cm random error in GPS observations.
-The improvement largely resulted from the improved technique (multi-matrix), which is why we created it. 
-Future models will adopt a similar modeling approach.

## Composite Geoids

**Composite Geoids**

- Gravity Geoid  systematic misfit with benchmarks
- Composite Geoid biased to fit local benchmarks
- e = h – H – N       “mis-fit”

**Earth’s Surface**

**Ellipsoid**

**Hybrid or Composite Geoid =~ NAVD 88**

**Gravity**** Geoid**

**e = 0.064 M in **
**Independance, MO – **
**1999 model**

**e = 0.021 M in **
**Independence, MO  – **
**2003 model**

**Notes:**
- Gravity geoid is from gravity measurements
- NAVD 88 bench marks are adjusted using a sea level height at Point au Pere
- There is going to be a slight difference between the 2.   If we want to use geoid to compute NAVD 88 heights, it must be consistent with the NAVD 88
Therefore we “bias” the geoid to be consistent with the NAVD 88 using high accuracy GPS on NAVD 88 bench marks.
Use Least Squares Collocation to determine the systematic components while allowing for random GPS observation errors (2-5 cm standard).
-Use the control points (GPSBM’s) to define a surface that can be interpolated to make internally consistent predictions (precision versus accuracy).
As you can easily see, the quality and distribution of the control, data will directly impact the quality of the predictions.

## Slide 37

**Notes:**
-These are the control data used to make GEOID03 (GPS on bench marks: GPSBM’s).
-Note the inequitable distribution.
-You could practically grid the GPSBM’s in South Carolina and get a good result.
-Other places are not so fortunate...
-Also note that this shows distribution but not quality of the points. 
-Some regions (e.g., Texas) have systematic problems that impact the GPSBM’s and the derived hybrid geoids.
-Current techniques rely on creating models of the systematic effects at multiple wavelengths. If the spatial density doesn’t support the shorter wavelength models, then the quality of predictions will commensurately be reduced.

## Geoid99 – GPS on Bench Marks

**-2.0**

**4.0**

**1.4**

**1.7**

**-6.7**

**2.9**

**6.9**

**2.6**

**6.4**

**10.7**

**6.9**

**-8.2**

**-4.4**

**7.0**

**Misfit (cm)**
**NAVD88+GH-EH=**

**3.0**

## Geoid03 – GPS on Bench Marks

**4.0****/****2.0**

**1.4****/****3.0**

**1.7****/****-2.0**

**-6.7****/****-0.3**

**2.9****/****0.4**

**6.9****/****4.0**

**2.6****/****3.0**

**6.4****/****2.0**

**10.7****/****2.0**

**6.9****/****8.0**

**-8.2****/****-3.0**

**-4.4****/****1.0**

**7.0****/****2.0**

**Disagreement (cm)**
** ****NAVD88+GH-EH=**
-    Geoid99/Geoid03

**3.0****/****-0.3**

## Sample Datasheet

-        **KE1114  FBN         -  This is a Federal Base Network Control Station.**
** ****KE1114  DESIGNATION -  W 328**
** ****KE1114  PID         -  KE1114**
** ****KE1114  STATE/COUNTY-  MO/JACKSON**
** ****KE1114  USGS QUAD   -  INDEPENDENCE (1990)**
** ****KE1114**
** ****KE1114                         *CURRENT SURVEY CONTROL**
** ****KE1114  ___________________________________________________________________**
** ****KE1114* NAD 83(1997)-  39 06 04.81201(N)    094 24 42.31977(W)     ADJUSTED  **
** ****KE1114* NAVD 88     -       311.238  (meters)    1021.12   (feet)  ADJUSTED  **
** ****KE1114  ___________________________________________________________________**
** ****KE1114  X           -    -381,268.407 (meters)                     COMP**
** ****KE1114  Y           -  -4,941,769.954 (meters)                     COMP**
** ****KE1114  Z           -   4,001,229.425 (meters)                     COMP**
** ****KE1114  LAPLACE CORR-          -1.12  (seconds)                    DEFLEC99**
** ****KE1114  ELLIP HEIGHT-         278.657 (meters)          (02/11/04) GPS OBS**
** ****KE1114  GEOID HEIGHT-         -32.56  (meters)                     GEOID03**
** ****KE1114  DYNAMIC HT  -         311.035 (meters)    1020.45  (feet)  COMP**
** ****KE1114  MODELED GRAV-     979,965.6   (mgal)                       NAVD 88**
** ****KE1114**
** ****KE1114  HORZ ORDER  -  B**
** ****KE1114  VERT ORDER  -  FIRST     CLASS II**
** ****KE1114  ELLP ORDER  -  FOURTH    CLASS I**
** **

**Sample Datasheet**

**N**

**H**

**h**

**Notes:**
NGS datasheets show all heights where we have them.

## 
 KE1114.The horizontal coordinates were established by GPS observations
 KE1114.and adjusted by the National Geodetic Survey in December 1997.
 KE1114
 KE1114.The orthometric height was determined by differential leveling
 KE1114.and adjusted by the NATIONAL GEODETIC SURVEY in June 1991.
 KE1114
 KE1114.The X, Y, and Z were computed from the position and the ellipsoidal ht.
 KE1114
 KE1114.The Laplace correction was computed from DEFLEC99 derived deflections.
 KE1114
 KE1114.The ellipsoidal height was determined by GPS observations
 KE1114.and is referenced to NAD 83.
 KE1114
 KE1114.The geoid height was determined by GEOID03.
 KE1114
 KE1114.The dynamic height is computed by dividing the NAVD 88
 KE1114.geopotential number by the normal gravity value computed on the
 KE1114.Geodetic Reference System of 1980 (GRS 80) ellipsoid at 45
 KE1114.degrees latitude (g = 980.6199 gals.).
 KE1114
 KE1114.The modeled gravity was interpolated from observed gravity values.
 KE1114

** ****KE1114.The horizontal coordinates were established by GPS observations**
** ****KE1114.and adjusted by the National Geodetic Survey in December 1997.**
** ****KE1114**
** ****KE1114.The **_**orthometric height was determined by differential leveling**_
** ****KE1114.and **_**adjusted by the NATIONAL GEODETIC SURVEY in June 1991**_**.**
** ****KE1114**
** ****KE1114.The X, Y, and Z were computed from the position and the ellipsoidal ht.**
** ****KE1114**
** ****KE1114.The Laplace correction was computed from DEFLEC99 derived deflections.**
** ****KE1114**
** ****KE1114.The **_**ellipsoidal height was determined by GPS observations**_
** ****KE1114.and is referenced to NAD 83.**
** ****KE1114**
** ****KE1114.The **_**geoid height was determined by GEOID03**_**.**
** ****KE1114**
** ****KE1114.The dynamic height is computed by dividing the NAVD 88**
** ****KE1114.geopotential number by the normal gravity value computed on the**
** ****KE1114.Geodetic Reference System of 1980 (GRS 80) ellipsoid at 45**
** ****KE1114.degrees latitude (g = 980.6199 gals.).**
** ****KE1114**
** ****KE1114.The modeled gravity was interpolated from observed gravity values.**
** ****KE1114**

**Sample Datasheet**

**Notes:**
NGS datasheets show all heights where we have them.

## 
 KE1114;                    North         East     Units Scale Factor Converg.
 KE1114;SPC MO W     -   325,702.474   857,632.940   MT  0.99994189   +0 03 20.4
 KE1114;UTM  15      - 4,328,970.754   377,925.629   MT  0.99978349   -0 53 25.8
 KE1114
 KE1114!             -  Elev Factor  x  Scale Factor =   Combined Factor
 KE1114!SPC MO W     -   0.99995628  x   0.99994189  =   0.99989817
 KE1114!UTM  15      -   0.99995628  x   0.99978349  =   0.99973978
 KE1114
 KE1114                          SUPERSEDED SURVEY CONTROL
 KE1114
 KE1114  ELLIP H (12/22/97)  278.673  (m)                       GP(       ) 4 1
 KE1114  NAVD 88 (12/22/97)  311.24   (m)         1021.1    (f) LEVELING    3  
 KE1114
 KE1114.Superseded values are not recommended for survey control.
 KE1114.NGS no longer adjusts projects to the NAD 27 or NGVD 29 datums.
 KE1114.See file dsdata.txt  <http://www.ngs.noaa.gov/cgi-
       bin/ds_lookup.prl?Item=HOW_SUP_DET>to determine how the superseded data
       were derived.

** ****KE1114;                    North         East     Units Scale Factor Converg.**
** ****KE1114;SPC MO W     -   325,702.474   857,632.940   MT  0.99994189   +0 03 20.4**
** ****KE1114;UTM  15      - 4,328,970.754   377,925.629   MT  0.99978349   -0 53 25.8**
** ****KE1114**
** ****KE1114!             -  Elev Factor  x  Scale Factor =   Combined Factor**
** ****KE1114!SPC MO W     -   0.99995628  x   0.99994189  =   0.99989817**
** ****KE1114!UTM  15      -   0.99995628  x   0.99978349  =   0.99973978**
** ****KE1114**
** ****KE1114                          SUPERSEDED SURVEY CONTROL**
** ****KE1114**
** ****KE1114  ELLIP H (12/22/97)  278.673  (m)                       GP(       ) 4 1**
** ****KE1114  NAVD 88 (12/22/97)  311.24   (m)         1021.1    (f) LEVELING    3  **
** ****KE1114**
** ****KE1114.Superseded values are not recommended for survey control.**
** ****KE1114.NGS no longer adjusts projects to the NAD 27 or NGVD 29 datums.**
** ****KE1114.See file dsdata.txt  <http://www.ngs.noaa.gov/cgi-**
**       ****bin/ds_lookup.prl?Item=HOW_SUP_DET>to determine how the superseded data**
**       ****were derived.**

**Sample Datasheet**

**Notes:**
NGS datasheets show all heights where we have them.

## 
 KE1114
 KE1114_U.S. NATIONAL GRID SPATIAL ADDRESS: 15SUD7792628971(NAD 83)
 KE1114_MARKER: I = METAL ROD
 KE1114_SETTING: 49 = STAINLESS STEEL ROD W/O SLEEVE (10 FT.+)
 KE1114_SP_SET: STAINLESS STEEL ROD
 KE1114_STAMPING: W 328 1986
 KE1114_MARK LOGO: NGS   
 KE1114_PROJECTION: FLUSH
 KE1114_MAGNETIC: N = NO MAGNETIC MATERIAL
 KE1114_STABILITY: B = PROBABLY HOLD POSITION/ELEVATION WELL
 KE1114_SATELLITE: THE SITE LOCATION WAS REPORTED AS SUITABLE FOR
 KE1114+SATELLITE: SATELLITE OBSERVATIONS - July 23, 2005
 KE1114_ROD/PIPE-DEPTH: 5.80 meters
 KE1114
 KE1114  HISTORY     - Date     Condition        Report By
 KE1114  HISTORY     - 1986     MONUMENTED       NGS
 KE1114  HISTORY     - 19970211 GOOD             NGS
 KE1114  HISTORY     - 19970528 GOOD             NGS
 KE1114  HISTORY     - 19990728 GOOD             NGS
 KE1114  HISTORY     - 20010322 GOOD             SKW
 KE1114  HISTORY     - 20030724 GOOD             MODNR
 KE1114  HISTORY     - 20030804 GOOD             MODNR
 KE1114  HISTORY     - 20050723 GOOD             GEOCAC
 KE1114
 KE1114                          STATION DESCRIPTION
 KE1114
 KE1114'DESCRIBED BY NATIONAL GEODETIC SURVEY 1986
 KE1114'IN INDEPENDENCE.
 KE1114'IN INDEPENDENCE, AT THE INTERSECTION OF U.S. HIGHWAY 24 AND NOLAND
 KE1114'ROAD, 90.5 M (296.9 FT) EAST OF THE ROAD CENTER, 9.7 M (31.8 FT) NORTH

** ****KE1114**
** ****KE1114_U.S. NATIONAL GRID SPATIAL ADDRESS: 15SUD7792628971(NAD 83)**
** ****KE1114_MARKER: I = METAL ROD**
** ****KE1114_SETTING: 49 = STAINLESS STEEL ROD W/O SLEEVE (10 FT.+)**
** ****KE1114_SP_SET: STAINLESS STEEL ROD**
** ****KE1114_STAMPING: W 328 1986**
** ****KE1114_MARK LOGO: NGS   **
** ****KE1114_PROJECTION: FLUSH**
** ****KE1114_MAGNETIC: N = NO MAGNETIC MATERIAL**
** ****KE1114_STABILITY: B = PROBABLY HOLD POSITION/ELEVATION WELL**
** ****KE1114_SATELLITE: THE SITE LOCATION WAS REPORTED AS SUITABLE FOR**
** ****KE1114+SATELLITE: SATELLITE OBSERVATIONS - July 23, 2005**
** ****KE1114_ROD/PIPE-DEPTH: 5.80 meters**
** ****KE1114**
** ****KE1114  HISTORY     - Date     Condition        Report By**
** ****KE1114  HISTORY     - 1986     MONUMENTED       NGS**
** ****KE1114  HISTORY     - 19970211 GOOD             NGS**
** ****KE1114  HISTORY     - 19970528 GOOD             NGS**
** ****KE1114  HISTORY     - 19990728 GOOD             NGS**
** ****KE1114  HISTORY     - 20010322 GOOD             SKW**
** ****KE1114  HISTORY     - 20030724 GOOD             MODNR**
** ****KE1114  HISTORY     - 20030804 GOOD             MODNR**
** ****KE1114  HISTORY     - 20050723 GOOD             GEOCAC**
** ****KE1114**
** ****KE1114                          STATION DESCRIPTION**
** ****KE1114**
** ****KE1114'DESCRIBED BY NATIONAL GEODETIC SURVEY 1986**
** ****KE1114'IN INDEPENDENCE.**
** ****KE1114'IN INDEPENDENCE, AT THE INTERSECTION OF U.S. HIGHWAY 24 AND NOLAND**
** ****KE1114'ROAD, 90.5 M (296.9 FT) EAST OF THE ROAD CENTER, 9.7 M (31.8 FT) NORTH**
** **

**Sample Datasheet**

**Notes:**
NGS datasheets show all heights where we have them.

## Sample Datasheet

-        **KE1114  FBN         -  This is a Federal Base Network Control Station.**
** ****KE1114  DESIGNATION -  W 328**
** ****KE1114  PID         -  KE1114**
** ****KE1114  STATE/COUNTY-  MO/JACKSON**
** ****KE1114  USGS QUAD   -  INDEPENDENCE (1990)**
** ****KE1114**
** ****KE1114                         *CURRENT SURVEY CONTROL**
** ****KE1114  ___________________________________________________________________**
** ****KE1114* NAD 83(1997)-  39 06 04.81201(N)    094 24 42.31977(W)     ADJUSTED  **
** ****KE1114* NAVD 88     -       311.238  (meters)    1021.12   (feet)  ADJUSTED  **
** ****KE1114  ___________________________________________________________________**
** ****KE1114  X           -    -381,268.407 (meters)                     COMP**
** ****KE1114  Y           -  -4,941,769.954 (meters)                     COMP**
** ****KE1114  Z           -   4,001,229.425 (meters)                     COMP**
** ****KE1114  LAPLACE CORR-          -1.12  (seconds)                    DEFLEC99**
** ****KE1114  ELLIP HEIGHT-         278.657 (meters)          (02/11/04) GPS OBS**
** ****KE1114  GEOID HEIGHT-         -32.56  (meters)                     GEOID03**
** ****KE1114  DYNAMIC HT  -         311.035 (meters)    1020.45  (feet)  COMP**
** ****KE1114  MODELED GRAV-     979,965.6   (mgal)                       NAVD 88**
** ****KE1114**
** ****KE1114  HORZ ORDER  -  B**
** ****KE1114  VERT ORDER  -  FIRST     CLASS II**
** ****KE1114  ELLP ORDER  -  FOURTH    CLASS I**
** **

**Sample Datasheet**

**N**

**H**

**h**

- NAVD88 – Ellipsoid Ht + Geoid Ht = ...
- 311.238 – 278.657 – 16.93 =  -0.551   USGG2003
- 311.238 – 278.657 – 16.65 =  +0.021   GEOID03

**Notes:**
NGS datasheets show all heights where we have them.

## The Missing Link

- Leveling-Derived Orthometric Heights
- Modeled Geoid Heights
_**What’s left?**_

**Notes:**
We know how to get 
  - Accurate orthometric heights at benchmarks by leveling – this is expensive and time consuming!  But these are still the best heights you can get.

We now are able to develop a hybrid geoid model from a gravimetric geoid model with
 - Accurate ellipsoid heights
 - More benchmarks with GPS measurements – the better the NAVD88, the better the geoid model

How do we get improved ellipsoid heights?
Better field procedures
Accurate ellipsoid heights at control stations

**H**

**H = Orthometric Height**  **(NAVD 88)**

**H** ** = ****h**** - ****N**

- TOPOGRAPHIC SURFACE

**h = Ellipsoidal Height (NAD 83)**

**N = Geoid Height (GEOID 03)**

**Ellipsoid, Geoid, ****and Orthometric Heights**

- A

- B

**Notes:**
Orthometric height is the height on the surface above the geoid.  But we can’t measure from the geoid so we use leveling. The NAVD88 is defined from the control point, B, in Quebec.  Because the ortho ht at A is computed from leveling observations, where error is modeled or estimated, it probably isn’t right at the geoid, right at “sea level”.

Our vertical datum is defined.  We need a geoid that we can use that is relative to the vertical datum. 

Note that in this picture the geoid is shown above the ellipsoid.  In the continental United States, the geoid is actually below the ellipsoid, so the value of the geoid height is negative.

## enter GPS...

***enter GPS...***

***(******GNSS******)***

## Height Modernization is ...

- ...the establishment of accurate, reliable heights using GNSS technology in conjunction with traditional leveling, gravity, and modern remote sensing information....

## Height Modernization Objective

** **** **

**NSRS**

**NAVD 88**

**GEODETIC CONTROL**

**Reliable**

**Cost-effective**

**Accurate**

**Standardized**

**Legally Established**

** ****D E F I N I T I O N**

**Notes:**
Information about where an object or feature is or where an event takes place is known as spatial data.  We use spatial data all the time. 
National Spatial Reference System – a consistent coordinate system that defines latitude, longitude, height, scale, gravity, and orientation throughout the United States and how these values change with time.  Comprised of an accurate, up-to-date national shoreline, a network of CORS (Continuously Operating Reference Stations), a network of ground monuments, and a set of accurate models that describe processes affecting spatial measurements.
Spatial data is crucial to economy, resource management, the environment and emergency response.
Transportation - Surface waters - Boundaries - Geodetic control - Elevation - Aerial imagery 
National Spatial Data Infrastructure – Formalized effort of the federal, state and local government, private groups to develop and use a consistent, reliable means to share spatial data.
Geodetic control is NGS’ responsibility.

## The Roots of Height Modernization

**In 1994** - First meeting held in Sacramento, CA
**In 1998**, $1.0 M was added to NGS budget to perform Height Modernization Study
**2000** - $500K added to NGS’ budget for Height Modernization planning
**2001** - $2.25M added to NGS budget to implement Height                      Modernization
**2001 -** NOAA directed to                       work with LA and WI to                        assess their requirements                          for Height Modernization

** ****B A C K G R O U N D**

**Notes:**
History 
California first state to draw attention to deficit in NAVD 88.  Hard to pin down movement in CA.  A lot of the state did not get adjusted in NAVD 88.  Especially southern California because the leveling was so old.  Grassroots effort to begin Height Modernization.
Earthquakes shown as red are > or = to 4.0 and occurred between 1852-2001
Earthquakes shown in yellow are > or = 6.5 and occurred between 1852-2003
In 1997, Height Modernization was mentioned in our appropriation language for the first time. No money allocated, but NGS encouraged to investigate the concept of height modernization.
In 1998, $1.0 M was added to NGS budget to perform Height Modernization Study.
In 1999,  Height Modernization not mentioned.
In 2000, $500K added to NGS budget to perform Height Modernization planning.
In 2001, $2.25 M added to NGS budget to perform Height Modernization in North Carolina, to support the California Spatial Reference Center (CSRC), and to support NGS related Height Modernization activities.
Also In June 2001, NGS was directed to report to Congress about the Height Mod needs of LA and WI. LA had similar issues with data not being adjusted into NAVD 88.  (Due to subsidence). WI had a very active Height Mod program by the WisDOT. Very active in GIS. Problems with obsolete geodetic control & rapid land loss thru subsidence and erosion.

## Height Modernization Appropriations

- (FY01-FY06)

| Fiscal Year | Appropriations  | States |
| --- | --- | --- |
| FY 2001 | 2.25 M | CA, NC |
| FY 2002 | 3.75 M |   CA, NC, LA, WI |
| FY 2003 | 3.75 M | CA, NC, LA, WI, MS |
| FY 2004 | 9.0 M | CA, NC, LA, WI, MS, 
AL, WA, SC |
| FY 2005 | 9.6 M | CA, NC, LA, WI, MS, 
AL, WA, TX, KY |
| FY 2006 | 9.9 M | CA, NC, WI, MS, 
AL, SC, TX, KY, AZ |
| FY 2007 | 9.0 M | “... without direction” |

** ****B A C K G R O U N D**

**Notes:**
FY 2001: CA 1.0M, NC 1.0M, NGS 0.25M
FY 2002: CA 1.0M, NC 1.0M, LA 1.0M, WI 0.5M
FY 2003: CA 1.0M, NC 1.0M, LA 0.5M, WI 0.5M, MS 0.5M
FY 2004: CA 1.0M, NC 1.0M, LA 0.5M, WI 3.0M, MS 0.5M, AL 2.0M, SC 0.5M, WA 0.5M 
FY 2005: CA 0.5M, NC 1.0M, LA 0.5M, WI 3.0M, MS 0.6M, AL 2.0M, WA 0.5M, KY 0.5M, TX 0.75, NGS 0.25M
FY 2006: CA 0.93M, NC 0.93M, WI 3.0M, MS 0.6M, AL 1.97M, SC 0.467M, KY 0.5M, TX 1.6M, AZ 0.5M, NGS 0.233M

## FY06 Height Modernization - Recipients

| CA |  | California Spatial Reference Center at Scripps Institution of Oceanography  |
| --- | --- | --- |
| NC |  | North Carolina Department of Environmental and Natural Resources (and North Carolina A&T State University) |
| WI |  | Wisconsin Department of Transportation  |
| AL |  | Alabama Department of Revenue |
| MS |  | University of Southern Mississippi  |
| TX |  | Texas A&M University, Corpus Christi  |
| KY |  | Morehead State University |
| SC |  | South Carolina Geodetic Survey |
| AZ |  | Arizona State Land Development |
| NGS |  | Height Modernization Regional Expansion - NGS Implementation |

** ****B A C K G R O U N D**

## Height Modernization Program

## NGS’ Role and Responsibilities

**NGS’ Role and Responsibilities**

** ****O U T R E A C H  &  E D U C A T  I O N  **

## NGS’ Role and Responsibilities

- Michigan

- Leveling – Spokane, 2006

** ****O U T R E A C H  &  E D U C A T  I O N  **

**Education, Outreach, Technology Transfer** -- advisors, forums, workshops, conferences, publications, training, capacity building

**NGS’ Role and Responsibilities**

- Corbin Training Center, Fredericksburg, VA

**Notes:**
Further densify Control network – provide additional ellipsoid height control.  Include bench marks with published NAVD88 heights to get “GPS on bench marks” for the geoid model.

## NGS’ Role and Responsibilities

**NGS’ Role and Responsibilities**

** ****O U T R E A C H  &  E D U C A T  I O N  **

## Vertical Datum Transformation “Roadmap”

**NAD 83 (86)**

** ****NAVD 88**

**LMSL**

**MHHW**

**MHW**

**MTL**

**DTL**

**MLW**

**MLLW**

**WGS 84 (G873)**

**WGS 84 (G730)**

**WGS 84 (orig.)**

**ITRF97**

**ITRF94**

**ITRF96**

**ITRF93**

**ITRF92**

**ITRF91**

**ITRF90**

**ITRF89**

**ITRF88**

**SIO/MIT 92**

**NEOS 90**

**PNEOS 90**

**NGVD**** ****29**

**GEOID99**
**(USHG2003**
**USGG2003)**

**TSS**

**ITRF2000  **
**WGS 84 (G1150)**

**   ****Ellipsoids                      Datums                ****Datums**** **

**   ****3-D Datum                   Orthometric           ****Tidal **

##  AI6151  ___________________________________________________________________
 AI6151* NAD 83(1997)-  43 25 39.39446(N)    088 18 24.15369(W)     ADJUSTED  
 AI6151* NAVD 88     -       343.002  (meters)    1125.33   (feet)  ADJUSTED  
 AI6151  ___________________________________________________________________

** ****AI6151* NAD 83(1997)-  43 25 39.39446(N)    088 18 24.15369(W)     ADJUSTED  **
** ****AI6151* NAVD 88     -       343.002  (meters)    1125.33   (feet)  ADJUSTED  **
** ****AI6151  ___________________________________________________________________**

**... ****differential leveling and adjusted by the National Geodetic Survey in October 2000.**

**NGS’ Role and Responsibilities**

**Quality Control** -- training, assess techniques, survey control, load projects into NGS database

## High Accuracy Reference Network

**Notes:**
Further densify Control network – provide additional ellipsoid height control.  Include bench marks with published NAVD88 heights to get “GPS on bench marks” for the geoid model.

## NGS’ Role and Responsibilities

**NGS’ Role and Responsibilities**

** ****O U T R E A C H  &  E D U C A T  I O N  **

## Projects/Partnerships

- FEMA – Map Modernization, Post-Katrina recovery project

## Projects/Partnerships

- USACE – update levees nationally to NAVD88
-  Design process to survey levees
-  Provide 2 weeks of training for USGS District Datum experts Training
- NWS – update dunes and levees to NAVD88 – improve SLOSH models

## Projects/Partnerships

- NWS/USGS – update stream gages to NAVD88 to improve inundation models
-  Develop strategy to triage steam gage inventory
-  Identify accuracy requirements
-  Identify dynamic areas
-  Coordinate with existing projects
-  Design pilot project for ‘special’ areas  (subsiding, old datums)

## Hurricane Prediction Center
Tsunami warning system
 Virgin Islands leveling/GPS surveys
Gravity surveys – OR, NC, WA, PR

- Tsunami warning system
-  Virgin Islands leveling/GPS surveys
- Gravity surveys – OR, NC, WA, PR

**Projects/Partnerships**

## Questions?

**Renee Shields**
**Height Modernization Manager**
- N/NGS1, SSMC3, Room 9357
- 1315 East-West Highway
- Silver Spring, MD  20910
- 301-713-3231, x116
- Renee.Shields@noaa.gov

**Contact information**