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Home My WebLink AboutJeff Co 1991 GPS Project (3)National Geodetic Survey Survey Control Data Input File January 24, 1992 National Geodetic Survey Survey Control Data January 24, 1992 Index By Page Number TO: THE USERS OF THIS DOCUMENT FROM: DENNIS A WEGENAST GEODETIC ADVISOR STATE OF WASHINGTON SUBJECT: THE WASHINGTON STATE HIGH PRECISION GPS NETWORI< THE FOLLOWING DATA IS THE RESULT OF THE COOPERATIVE EFFORT OF OVER 50 PARTICIPANTS. IT IS DESIGNED FOR THE USE OF THE NEW SURVEY TECHNOLOGY OF GPS. THERE ARE A FEW THINGS YOU SHOULD BE AWARE OF WHEN USING THIS INFORMATION. 1. THIS INFORMATION IS THE RESULT OF ARE-ADJUSTMENT OF NAD 83 KNOWN AS NAD 83/91 AND NEEDS TO BE USED AS SUCH FOR SATISFACTORY CLOSURES. 2. THE STATE PLANE COORDINATES ARE LISTED IN METERS AND THE STATE OF WASHINGTON USES THE US SURVEY FOOT AS A STANDARD. 3. THE ELEVATIONS LISTED ON THE DATA SHEETS ARE A MIX OF NGVD 29 ~ND NAVD 88. THIS COULD CAUSE SOME PROBLEMS WHEN USING THE INFORMATION. THE REASON FOR THIS IS NGS HAS NOT BEEN ABLE TO COMPLETELY TRANSFORM IT'S HORIZONTAL DATA TO THE NEW VERTICAL DATUM AT THIS DATE. 4. FOR YOUR INCONVIENINCE THE INDEX IS IN THREE PARTS: A. THE STATION IN OREGON ARE LISTED SEPERATLY. B. FOUR STATIONS THAT WERE NOT LISTED IN THE WASHINGTON DATA ARE IN ADDENDUM 2. C. THE REST OF THE WASHINGTON DATA. IF AT ANY TIME YOU HAVE A PROBLEM WITH ANY OF THE STATIONS IN THIS NETWORK PLEASE CONTACT ME OR THE NATIONAL GEODETIC SURVEY IN ROCKVILLE MD 20852, MY PHONE NUMBER IS 206-586-5532 OR 206-355-9855, IN ROCKVILLE CALL 301-443-8218. ADDENDUM NUMBER 2 THE WASHINGTON STATE INDEX PUBLICATION DATE: APRIL 8 1992 DEPARTMENT OF COMMERCE NOAA - NOS - C~GS NATIONAL GEODETIC SURVEY National Geodetic Survey Survey Control Data January 24, 1992 Index DEPARTl\IENT OF COMMERCE NOAA - NOS - C&GS NATIONAL GEODETIC SURVEY PlTßLICATION DATE: APRIL 8, 1992 USGS QUAD SHEET: FORKS FORKS RESET P'D: SD0880 HORIZONTAL DATUM: NAD 83 (1991) VERTICAL DATUM: NGVD 29 STATE: WASHINGTON ÇOUNTY: CLALLAM LATITUDE: 47- 56' 12.18434" N :0.00070 SECONDS LONGITUDE: 124- 23' 44.17650w W ::0.00090 SECONDS ORTHOMETRlC HEIGHT- { 86.85 METERS · 284.9 FEET DEFLECTIONS: ~. -6.46 LAPLACE CORRECTION: GEOID HEIGHT: ELLIPSOIDAL HEIGHT: THE HORIZONTAL COORDINATES WERE ESTABLISHED BY GPS OBSERVATIONS AND ADJUSTED BY THE NATIONAL GEODETIC SURVEY IN MAY 1991 ~ THE ORTHOMETRIC HEIGHT WAS DETERMINED BY DIFFERENTIAL LEVELING, BUT THE HEIGHT HAS NOT BEEN ADJUSTED. HORIZONTAL DATUM NAD83 minus NAD27 LATITUDE -00.69966- LONGITUDE + 04 . 73250· (Based on Adlusted Positions) UNITS METERS METERS GRID ZONE - SPC WA N UTM 10 NORTHING 110,304.813 5,310,209.243 PLANE COORDINAT'ES POINT SCALE -GRID AZL\1lJTH TO FACTOR CONVERGENCE FORKS AZ MK 0.99994723 - 2- 39' 07.9" 05111 27' 26.5- 0.99973350 - t- 02' 10.3" 0490 50' 28.9" (eARC-TO-CHOAD CORAECT10N NOT APPLIED) EASTING 233.948.385 395.767.962 STATION MARKS AND REFERENCE OBJECTS REFERENCE OBJECT DIST~CE SD0178 S00178 FORKS AZ MK FORKS RM 1 FORKS RM 2 STATION MARK IS A HORIZONTAL CONTROL DISK WITH SETTING... . . . . . .. SET IN TOP OF CONCRETE MONUMENT (ROUND) THE MARK IS STAMPED... FORKS 1954 1990 STATION MARK HISTORY YEAR MONUMENTED OR RECOVERED 1990 CONDmON OF MARK RECOVERED OR DESCRJBED BY STATION MONUMENTED NATIONAL GEODETIC SURVEY (Continued on Next Page) DEPARTMENT OF COMMERCE NOAA - NOS -C&GS NATIONAL GEODETIC SURVEY PUBLICATION DATE: APRn., 8, 1992 USGS QUAD SHEET: FORKS FÐRKS~ ReSET PID:SD0880 STATION DESCRIPTION DEPARTMENT OF COMMERCE PUBLICATION DATE: JANUARY 24, 1992 NOAA - NOS - C&GS NATIONAL GEODETIC SURVEY 944 3090 A TIDAL PIC: 150340 HORIZONTAL DATUM: NAD 83 (1991) VERTICAL DATUM: NGVD 29 STATE: WASHINGTON COUNTY: CLALLAM LATITUDE: 48' 22' 00.74183" N ::0.00090 SECONDS LONGITUDE: 124' 37r 15.67186'" W ::0.00100 SECONDS ORTHOMETRIC HEIGHT: { 4.54 METERS 14.9 FEET DEFLECTIONS: ~= -8.86 f1= -8.46 SECONDS LAPLACE CORRECTION: 9.52 SECONDS GEOID HEIGHT: -19.78 METERS ELLIPSOIDAL HEIGHT: -14.957 ±o.222 METERS X: -2411951.636 METERS Y: -3493580.167 METERS z: 4744064.423 METERS HORIZONTAL NETWORK ORDER/CLASS: VERTICAL NETWORK ORDER/CLASS: THE HORIZONTAL COORDINATES WERE ESTABLISHED BY GPSOBSERVATIONS AND ADJUSTED BY THE NATIONAL GEODETIC SURVEY IN MAY 1991 THE ORTHOMETRIC HEIGHT WAS DETERMINED BY DIFFERENTIAL LEVELING. THE VERTICAL NETWORK TIE WAS PERFORMED BY A HORIZONTAL FIELD PARTY FOR HORIZONTAL OBSERVATION REDUCTIONS. RESET PROCEDURES WERE USED TO ESTABLISH THE ELEVATION. DEPARTMENT OF COMMERCE NOAA. - NOS - C&GS NATIONAL GEODETIC SURVEY 944 309-0 A TIDAL PID: T80340 PUBLICATION-DATE:JANUARY 24, 1992- STATION DESCRIPTION DEPARTMENT OF COMMERCE PUBLICATION DATE: JANUARY 24,1992 NOAA - NOS - C&GS NATIONAL GEODETIC SURVEY STATE: WASHINGTON COUNTY: CLALLAM LATITUDE: 480 07' 25.14370" N 1: o.OOOSO SECONDS LONGITUDE: 1230 27' 04.02353" W ± 0.00070 SECONDS ORTHOMETRIC HEIGHT: { 2.95 METERS 9.7 FEET HORIZONTAL NETWORK. ORDER/CLASS: VERTICAL NETWORK ORDER/CLASS: THE HORIZONTAL COORDINATES WERE ESTABLISHED BY GPS OBSERVATIONS AND ADJUSTED BY THE NATIONAL GEODETIC SURVEY IN MAY 1991 THE ORTHOMETRIC HEIGHT WAS DETERMINED BY DIFFERENTIAL LEVELING. THE VERTICAL NETWORK TIE WAS PERFORMED BY A HORIZONTAL FIELD PARTY FOR HORIZONTAL OBSERVATION REDUCTIONS. RESET PROCEDURES WERE USED TO ESTABLISH THE ELEVATION. POINT NORTHING EASTL1\lG SCALE CONVERGENCE GRID ZONE METERS METERS FACTOR DEG MIN SEC SPC WAN 128,244.280 305,163.031 0.99994226 - 1 56 56.4 UTM 10 5,330,142.076 466,429.182 0.99961385 - 0 20 09.2 STATION MARK IS A .... BENCH MARK DISK WITH SETTING....... . .. COPPER-CLAD ROD IN SLEEVE (10 FT.+) THE MARK IS STAMPED . .. 4090 A 1981 STATION MARK HISTORY YEAR MONUMENTED OR RECOVERED 1987 1989 CONDmON OF MARK STATION MONUMENTED GOOD GOOD RECOVERED OR DESCRIBED BY NATIONAL GEODETIC SURVEY (MAM) NATIONAL GEODETIC SURVEY (Continued on Next Page) NATIONAL GEODETIC SURVEY 944 409-0 A TIDAL PIC: TR2551 PUBLICATION DATE: JANUARY 24, 1992 STATION DESCRIPTION THE STATION IS LOCATED AT PORT Angeles DEPARTMENT OF NOAA · NOS - C&GS NATIONAL GEODETIC SURVEY PUBLICATION DATE: JANUARY 24, 1992 USGS QUAD SHEET: SEATTLE BREMERTON AIR PIC: SY5640 HORIZONTAL DATUM: NAD 83 (1991) VERTICAL DATUM: NGVD 29 STATE: WASHINGTON COUNTY: KITSAP LATITUDE: 4741 30' 00.33905" N :t 0.00050 SECONDS LONGITUDE: 1220 45' 26.58469" W 1: 0.00070 SECONDS ORTHOMETRIC HEIGHT: { 136.16 METERS 446.7 FEET DEFLECTIONS: ç= -1.46 LAPLACE CORRECTION: GEOID HEIGHT: ELLIPSOIDAL HEIGHT: SECONDS SECONDS METERS ±o.111 METERS METERS METERS METERS HORIZONTAL NETWORK ORDER/CLASS: VERTICAL NETWORK ORDER/CLASS: THE HORIZONTAL COORDINATES WERE ESTABLISHED BY GPS OBSERVATIONS AND ADJUSTED BY THE NATIONAL GEODETIC SURVEY IN MAY 1991 THE ORTHOMETRIC HEIGHT WAS DETERMINED BY DIFFERENTIAL LEVELING, BUT THE HEIGHT HAS NOT BEEN ADJUSTED. PLA1'Œ COORDINATES POINT - NORTHING EASTING SCALE CONVERGENCE GRID ZONE METERS METERS FACTOR DEG MIN SEC SPC WAN 57,413.706 355,050.475 0.99999998 - 1 25 57.0 UTM 10 5,260,768.722 518,272.158 0.99960410 + 0 10 44.0 STATION MARK IS A .... HORIZONTAL CONTROL DISK WITH SETTING. . . . . . . . .. SET IN TOP OF CONCRETE MONUMENT (ROUND) THE MARK IS STAMPED... BREMERTON AIR 1990 STATION MARK HISTORY YEAR MONUMENTED OR RECOVERED 1989 CONDmON OF MARK RECOVERED OR DESCRIBED BY STATION MONUMENTED NATIONAL GEODETIC SURVEY (Continued on Next Page) DEPARTMENT OF PUBLICATION DATE: JANUARY 24, 1992 NOAA ..NOS .. C&GS USGS QUAD SHEET: SEATTLE NATIONAL GEODETIC SURVEY BREMERTON AIR DEPARTMENT OF COMMERCE NOAA - NOS - C&GS NATIONAL GEODETIC SURVEY PUBLICATION DATE: JANUARY 24, 1992 USGS QUAD SHEET: SEQUIM CEDAR PID: TR2697 HORIZONTAL DATUM: NAD 83 (1991) VERTICAL DATUM: NGVD 29 STATE: WASHINGTON COUNTY: CLALLAM LATITUDE: 480 04' 50.32488" N :0.00070 SECONDS LONGITUDE: 1230 06' 14.70854" W to.00080 SECONDS ORTHOMETRIC HEIGHT: { 55.56 METERS 182.3 FEET DEFLECTIONS: ~= 6.50 f)= 7.36 SECONDS LAPLACE CORRECTION: -8.19 SECONDS GEOID HEIGHT: -19.93 METERS ELLIPSOIDAL HEIGHT: 35.887 ±o. 1 45 METERS HORIZONTAL NETWORK ORDER/CLASS: VERTICAL NETWORK ORDER/CLASS: THE HORIZONTAL COORDINATES WERE ESTABLISHED BY GPS OBSERVATIONS AND ADJUSTED BY THE NATIONAL GEODETIC SURVEY IN MAY 1991 THE ORTHOMETRIC HEIGHT WAS DETERMINED BY DIFFERENTIAL LEVELING, BUT THE HEIGHT HAS NOT BEEN ADJUSTED. NOAA - NQS - C&.GS NATIONAL GEODETIC SURVEY PUBLICATION DATE: JANUARY 24~ 1992 USGS QUAD SHEET: SEQUIM CEDAR PIC: TR2697 STATION DESCRIPTION NOAA NATIONAL GEODETIC SURVEY USGS QUAD SHEET: ELDON STATE: WASHINGTON CO : MASON NOAA - NOS- C&GS- NATIONAL GEODETIC SURVEY PUBLICATION DATE: FEBRUARY 21,1992 USGS QUAD SHEET: ELDON STATION DESCRIPTION NOAA - NOS - C&GS NATIONAL GEODETIC SURVEY DATE: JANUARY 24.1992 USGS QUAD SHEET: PORT TOWNSEND SOUTH NOAA -NOS- C&GS NATIONAL, GEODETIC SURVEY DATE: 1992 USGS QUAD SHEET: PORT TOWNSEND SOUTH STATION DESCRIPTION DESCRIBED ,1989 NOAA - NOS - C&GS NATIONAL GEODETIC SURVEY HORIZONTAL VERTICAL JANUARY 24,1992 USGS QUAD SHEET: SEATTLE KING OLAF PIC: SY5639 STATE: WASHINGTON COlTNTY: KITSAP LATITUDE: 47444' 05.09561" N :0.00030 SECONDS LONGITUDE: 1220 38' 53.00691" W : 0.00030 SECONDS NOAA ·-NOS.. C&GS : NATIONAL GEODETIC SURVEY PUBLICATION DATE: JANUARY 24, 1992 USGS QUAD SHEET: SEATTLE KING -- OLAF STATION DESCRIPTION NOAA - NOS - C&GS NATIONAL GEODETIC SURVEY PUBLICATION DATE: JANUARY 24,1992 N 469 PIC: TS0058 HORIZONTAL DATUM: NAD 83 (1991) VERTICAL DATUM: NAVD 88 CO: CLALLAM LATITUDE: 4841 11' 52.33991" N : 0.00050 SECONDS LONGITUDE: 1240 07' 08.36050" W :0.00080 SECONDS ORTHOMETRIC HEIGHT NOAA .. NOS - C&GS NATIONAL GEODETIC SURVEY Pl 1992 N 469 PtC: TS0058 STATION DESCRIPTION NOAA - NOS - C&GS NATIONAL GEODETIC SURVEY PUBLICATION DATE: JANUARY 24, 1992 USGS QUAD SHEET: SEATTLE PORT LUDLOW PIC: SY5659 HORIZONTAL DATUM: NAD 83 (1991) VERTICAL DATUM: NGVD 29 STATE: WASHINGTON COUNTY: JEFFERSON LATITUDE: 470 55' 17.92103" N =0.00070 SECONDS LONGITUDE: 1220 40' 57.07491" W = 0.00130 SECONDS ORTHOMETRIC HEIGHT: { 2.47 METERS 8.1 FEET DEFLECTIONS: ~= 0.93 11= 12.95 SECONDS LAPLACE CORRECTION: -14.35 SECONDS GEOID HEIGHT: -21 .06 METERS ELLIPSOIDAL HEIGHT: -18.247 ±o.136 METERS X: -2312304.753 METERS Y: -3604202.922 METERS z: 4711028.703 METERS HORIZONTAL NETWORK ORDER/CLASS: VERTICAL NETWORK ORDER/CLASS: B THIRD (Vertical Network Order Unconfirmed) .~ THE HORIZONTAL COORDINATES WERE ESTABLISHED BY GPS OBSERVATIONS AND ADJUSTED BY THE NATIONAL GEODETIC SURVEY IN MAY. 1991 THE ORTHOMETRIC HEIGHT WAS DETERMINED BY DIFFERENTIAL LEVELING. THE VERTICAL NETWORK TIE WAS PERFORMED BY A HORIZONTAL FIELD PARTY FOR HORIZONTAL OBSERVATION REDUCTIONS. RESET PROCEDURES WERE USED TO ESTABLISH THE ELEVATION. GRID SPC UTM NORTHING ZONE METERS POINT EASTING . SCALE CONVERGENCE ~ERS FACTOR DEG MIN SEC 361,815.371 0.99994810 - 1 22 36.3 523.718.347 0.99960691 + 0 14 08.3 STATION MARK IS A .... HORIZONTAL CONTROL DISK WITH SETT ING . . . . . . . . .. SET IN TOP OF CONCRETE MONUMENT (ROUND) THE MARK IS STAMPED... PORT LUDLOW 1990 ST AnON MARK mSTORY YEAR MONUMENTED OR RECOVERED 1990 CONDmON OF MARK . RECOVERED OR DESCRIBED BY STATION MONUMENTED NATIONAL GEODETIC SURVEY (Continued on Next Page) DEPARTMENT OF NOAA - NOS- C&GS-- NATIONAL GEODETIC SURVEY PUBLICATION.DATE: JANUARY 24,1992 USGS QUAD SHEET: SEATTLE PORT -LUDLOW STATION DESCRIPTION DEPARTlVlENT OF COMMERCE PUBLICATION DATE: JANUARY 24,1992 NOAA - NOS · C&GS USGS QUAD SHEET: QUILLAYUTE PRAIRIE NATIONAL GEODETIC SURVEY QUILLAYUTE RESET PID: SD0799 HORIZONTAL DATUM: NAD 83 (1991) VERTICAL DATUM: NGVD 29 STATE: Wi\SHINGTON COUNTY: CLALLAM LATITUDE: LONGITUDE: PUBLICATION DATE: JANUARY 24, 1992- ~NOAAH - NOS - C&GS USGS QUAD SHEET: QUILLAYUTE PRAIRIE NATIONAL GEODETIC SURVEY QUILLAYUTE RESET PIC:CSD0799 STATION DESCRIPTION NOAA - NOS - C&GS NATIONAL GEODETIC SURVEY DATE: JANUARY 24,1992 USGS QUAD SHEET: QUEETS QUIN PIC: 500881 HORIZONTAL DATUM: NAD 83 (1991) VERTICAL DATUM: NGVD 29 STATE: WASHINGTON COUNTY: JEFFERSON LATITUDE: 47° 32' 24.67640" N 1: 0.00060 SECONDS LONGITUDE: 1240 19' 55.03823" W ;: 0.00070 SECONDS ORmOMETRIC HEIGHT: { 11 .51 METERS 37.8 FEET ' DEFLECTIONS: ç:a -4.70 LAPLACE CORRECTION: GEOID HEIGHT: ELLIPSOIDAL HEIGHT: NORTHING METERS NOAA --NOS- C&GS NATIONAL GEODETIC SURVEY PUBLICATION DATE: JANUARY 24~ 1992 USGS QUAD SHEET: QUEETS QUIN STATION DESCRIPTION DESCRIBED 1990 NOAA - NOS - C&GS NATIONAL GEODETIC SURVEY PUBLICATION DATE: JANUARY 24, 1992 USGS QUAD SHEET: SEATTLE SCHOOL : SY5641 HORIZONTAL DATUM: NAD 83 (1991) VERTICAL DATUM: NGVD 29 STATE: WASHINGTON COUNTY: JEFFERSON NOAA - NOS - C&GS - NATIONAL GEODETIC SURVEY PUBLICATION DATE: JANUARY 24, 1992 USGS QUAD SHEET.: SEATTLE SCHOOL PID: SY5641 STATIÐNDESCRIPTION DESCRIBED ,1990 NOAA - NOS - C&GS NATIONAL GEODETIC SURVEY PUBLICATION DATE: JANUARY 24, 1992 USGS QUAD SHEET: SEATTLE SITAR RM 1 PIC: SY0902 . HORIZONTAL DATUM: NAD 83 (1991) VERTICAL DATUM: NGVD 29 STATE: WASHINGTON COUNTY: KITSAP LATITUDE: 47° 34' 15.48735" N : 0.00020 SECONDS LONGITUDE: 1220 33' 09.23914H W :0.00030 SECONDS ORTHOMETRIC HEIGHT: { ~633 METERS 1 5.20 FEET DEFLECTIONS: ~= 9.57 .,= 11.30 SECONDS LAPLACE CORRECTION: -12.37 SECONDS GEOID HEIGHT: -21 .87 METERS ELLIPSOIDAL HEIGHT: -17.138 !a.OSS METERS X: -2319652.835 METERS Y: -3633764.360 METERS z: 4684812.163 METERS HORIZONTAL NETWORK ORDER/CLASS: VERTICAL NETWORK ORDER/CLASS: B SECOND THE HORIZONTAL COORDINATES WERE ESTABLISHED BY GPS OBSERVATIONS AND ADJUSTED BY THE NATIONAL GEODETIC SURVEY IN MAY 1991 THE ORTHOMETRIC HEIGHT WAS DETERMINED BY DIFFERENTIAL LEVELING AND ADJUSTED BY THE NATIONAL GEODETIC SURVEY. GRID SPC UTM ZONE WAN 10 NORTHING METERS 64,926.360 5,268,713.957 EASTING METERS 370,653.878 533,652.290 PLANE COORDINATES POINT ·GRID AZIMUTH TO SCALE CONVERGENCE ALKI ALKI SW BASE FACTOR DEG MIN SEC DEG MI.N SEC 0.99998752 - 1 16 48.0 087 57 52.2 0.99961392 + 0 19 48.9 086 2115.3 (*ARc-rO-CHORD CORRECTION NOT APPUED) STATION MARKS AND REFERENCE OBJECTS SY 4632 SY0903 SY0900 ALKI ALKI SW BASE SITAR R 255 APPROX.10.0 KM 117.73Ö·METERS 58.697 METERS GEODETIC AZIMUTH 086 41 04.2 258 50 309 22 pm REFERENCE OBJECT DISTANCE STATION MARK IS A .... REFERENCE MARK DISK WITH SETTING. . . . . . . . .. SET IN A MAT FOUNDATION OR CONCRETE SLAB OTHER THAN PAVEMENT THE MARK IS STAMPED . .. SITAR NO 1 1974 YEAR MONUMENTED OR RECOVERED 1974 1987 1989 CONDITION OF MARK RECOVERED OR DESCRIBED BY STATION MONUMENTED GOOD GOOD NATIONAL GEODETIC SURVEY NATIONAL GEODETIC SURVEY (DAW) NATIONAL GEODETIC SURVEY (Continued on Next Page) NOAA-NOS - C&GS NATIONAL GEODETIC SURVEY PUBLICATION DATE: JANUARY 24, 1992 USGS QUAD SHEET: SEATTLE SITAR RM 1 - PID:SY0902 STATION DESCRIPTION STATION RECOVERY (1987) MEMORANDUM FOR: Distribution FROM: William E.Strange Chief Geodesist SUBJECT: provision of Ellipsoid Height:s Information General Consideration In the past, ellipsoid heights were determined indirectly combining estimates of orthometric height and geoid height Great accuracy was not required since the primary use for ellipsoid he-ights was to reduce conventional geodetic data to· ellipsoid to allow adjustments to be performed. For this . purpose, l-meter accuracy would allow 1:6,000,000 accuracy and was certainly adequate considering that 1: 100,000 was the stated accuracy goal. with the advent of GPS, the situation is entirely different. GPS isa three-dimensional system and provides directly, not only estimates of differences in horizontal position (, ) but also estimates of differences in vertical position and, therefore, in ellipsoidal height. In fact, as a practical matter, GPS computations are performed in cartesian coordinates (X, Y, Z) and are only after the fact converted to ellipsoidal coordinates ( , ,h). There are two impacts of GPS on how ellipsoid heights must be viewed. First, because GPS is a three-dimensional system, the coordinates of a reference network station must be known in all three dimensipns with, as near as possible, equal accuracy to allow three-dimensional adjustments to be performed without distortions. Second, an ultimate aim is to use GPS- A number of points must be considered. An important point is the lack of commonality between the reference systems to which ellipsoid heights, orthometric heights, and geoid heights, as we commonly obtain them, are referred. Geoid heights are computed gravimetrically and are, therefore, nominally geoéentric. Geoid computations make use of gravity anomalies, the difference between observed gravity and a reference gravity formula. The reference gravity formula defines a reference figure. In essence, leveling measures orthometric heights, i.e., heights above a reference equipotential surface, and is, therefore, geocentric in nature. The exact reference equipotential surface being used is defined by use of tide gauges to specify an equipotential surface which in some sense corresponds to mean sea level. GPS-derived ellipsoid heights in the NAD 83 coordinate system are not geocentric quantities since the NAD 83 coordinate system is not-exactly a geocentric system. It is common to write a relation between orthometric height, ellipsoid height, and geoid height in the form: where: h = H = N = ellipsoid height orthometric height geoid height However, as we currently compute these quantities we cannot expect them to satisfy this formula, even leaving aside measurement error. We do not know that zero orthometric height lies on the geoid; in fact, there is every reason to believe that it does not. Also, since orthometric height and geoid height are nominally referred to 'a geocentric coordinate system while ellipsoid height is not, one cannot expect to add Hand N and get h. Given that formula (1) does not hold we should consider how the user would be expected to use the various types of height information. 1. Many users use leveled orthometric heights to provide starting values for leveling. These users will not be interested in geoid or ellipsoid heights. 2. Some users will perform local horizontal surveys by conventional means. These users would be interested, at most, in an ellipsoid height for reduction to the ellipsoid in adjusting the horizontal observations. For this user the differences between ellipsoid height as determined from GPS and ellipsoid height computed, using orthometric and geoid height is unlikely to be of importance. The only exception to this would be' two stations very close together with ellipsoid height 3 determined one way at one and the other way at the other. 3. If a user is employing GPS to determine horizontal positions at new stations, he would want to use reference stations where GPS-derived ellipsoid heights are available. To try to mix reference stations with GPS-derived ellipsoid heights and ellipsoid heights computed using orthometric heights and geoid heights could lead to distortions during ,adjustments. 40 If a user is employing GPS to determine orthometric height information in addition to, or instead of, horizontal information he would, at present, generally proceed in the following manner. The GPS survey would occupy bench marks where leveled orthometric heights are available that bound the GPS survey area. The difference between geoid heights obtained from GEOID 90 (or some other geoid estimate) and geoid heights obtained from differencing leveling-derived orthometric heights and GPS-required ellipsoid heights would be computed at the bounding bench marks. These differences would be used to derive a transformation to be applied to GEOID 90 geoid heights at other stations of the GPS survey. These transformed geoid heights would then be subtracted from the GPS ellipsoid heights to obtain orthometric heights. ~ Conclusions The above considerations indicate that GPS-derived ellipsoid heights, gravity-derived geoid heights and leveling, etc., derived orthometric heights should be carried in any data base or on any data sheet as independent entities which are not expected to satisfy equation (1). All are needed for various purposes but, as currently computed, are not compatible and cannot be expected to satisfy equation (1). They cannot be compatible until the cartesian reference system used is changed from NAD 83 to a geocentric-system and the vertical reference equipotential is made totally compatible with the geoid, as defined, using gravity anomalies. with respect to GPS-derived ellipsoid heights, these can only be consistent nationwide for GPS surveys which can be related to Order A or Order B network stations, either directly or secondarily. Thus, only these types of surveys should have ellipsoid height information provided. Such an internally consistent set of ellipsoia heights is essential, if GPS is ever to replace leveling in providing a height reference system. 4 Recommendations GPS- (or VLBI)derived ellipsoid heights should be published for all Order A and Order B stations and for all stations whose positions. are determined by GPS surveys connected directly or indirectly to the Order A and Order B stations. o All three height quantities should be published to the same number of significant places, probably to the millimeter. o Accuracy estimates should be given for geoid height and ellipsoid height in centimeters. o Ellipsoid height accuracy should come out of the GPS adjustment. o Where there is no GPS-derived ellipsoid height, the value would be left blank. o The statement to be made would be either "GPS-derived ellipsoid height relative to GRS 80 ellipsoid in NAD 83 coordinate system" or, if no values given, "No GPS- derived ellipsoid height available." For those stations where GPS-derivedthree-dimensional data are available X, Y, Z values should be provided as well as h. Distribution N/CGl - A. Bodnar N/CGl - M. Grunthal N/CGll - D. Milbert N/CG12 - E. Wade N/CG122 - s. Frakes N/CG13 - E. McKay N/CG13 - D. zilkoski N/CG14 - C. Challstrom N/CG14 - J. Love N/CG14 - P. Spofford UNITED STATES DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administratlan NATIONAL OCEAN SERVICE ROCKVILLE FROM: Dennis wegenast washington state Geodetic Advisor to· MEMORANDUM FOR: Washington HPGN Final Coordinates As you requested, attached are the final NAD83 (1991) order A and B coordinates for the washington state HPGN survey. Included also are the ellipsoidal heights. We have not yet completed the vertical adjustment to get the orthometric heights (although we are very close thanks to the help of Dennis Hilbert with the analysis and the extra hours put in by Kathy.Milbert). The report. and final listings with orthometric heights should be available next week. National Geodetic Survey Survey Control Data January 24, 1992 Explanation of Data National Geodetic Survey Survey Control Data January 24, 1992 Final Coordinate Listing National Geodetic Survey Survey Control Data January 24, 1992 Fianl Coordinate Listing National Geodetic Survey Survey Control Data January 24, 1992 Final Coordinate Listing National Geodetic Survey Survey Control Data January 24, 1992 Fianl Coordinate Listing National Geodetic Survey Survey Control Data January 24, 1992 Final Coordinate Listing National Geodetic Survey Survey Control Data January 24, 1992 Final Coordinate Listing National Geodetic Survey Survey Control Data January 24, 1992 Final Coordinate Listing National Geodetic Survey Survey Control Data January 24, 1992 Final Coordinate Listing EAGLE GPS Survey Corporation May 3, 1991 Mr. Bruce Laurie Construction Engineer Jefferson County Dept. of Public Works P.o. Box 1220 Port Townsend, WA 98368 RE: GPS Photo Control Survey Job No. 90-004 Bruce: It was a pleasure working with you and your staff on the photo control project in Jefferson County. Tom Morello and Bruce Brodahl made the job proceed very smoothly. They are an asset to their profession. The adjustment and final report have been completed, except for the Network Diagram. Enclosed are the following: 1. Three ring binder containing the following: Geodetic, state plane and elevation values for all stations occupied. Print out of loop closures 200 series only. Constrained adjustment. 2. (5) 3 1/2", 1.4 mg. disks containing the following: Minimally constrained adjustment. Constrained adjustment. All loop closures. 13545 N.W. Science Park Drive Portland, Oregon 97229 (503) 643-1073 Geodetic, state plane and elevation list. We are preparing a Network Diagram for the project. When it is finished, you will be provided a mylar and a 3 1/2" 1.4 mg. disk in Auto Cadd. If you have any questions, please call. Very truly yours, Walter L. Caswell WLC:km