C:\excerc\GEOD98e.E12.wpd

Geofysisk Afdeling, Juliane Maries vej 30, 2100 København Ø.

Geodesy Course, Exercise 12.

The purpose of the exercise is to demonstrate how height measurements from a satellite can be used to make a map of the sea-surface topography. It is also demostrated how the subtraction of heights calculated from a spherical harmonic model can enhance the geological features, in this case a sea-mount (volcano) on the bottom of the ocean.

Select first data from a file named
/disk1/cct/geod/altimetry. For this purpose use the program /disk1/cct/dgravsoft/selectn.

input: inputfile and outputfile (two lines):
/disk1/cct/geod/altimetry
alt.e12
input: MODE (0:reformat, 1:select, 2:mean, 3:grid, 4:plot,
5:sel&rej, 6:sel&wndw, 7:sel&rej&wndw, 8:sel&noise)
IANG (1:deg, 2:dm, 3:dms, 4:alt, 5:bin, 6:80char, 7:grid,
8: alt1, 9: alt (NewEng.), neg:fmt, 0:dline)
NDATA
1 9 2
input: FI1,FI2,LA1,LA2,DFI,DLA (deg or m)
38.5 39.5 -64.5 -63.5 0.0 0.0 (Here may also be selected another area)

-- S E L E C T ---
total points: 4057
located within area: 38.0001 39.9996 -64.9998 -63.0002
no of output/selected points: 999, total poss. pixels: 0
selected data: mean std.dev. min max
no: 1 -32.22 0.98 -34.83 -29.55
no: 2 0.19 0.04 0.02 0.20

Output tells how many values are found inside
the given area, the mean value and standard deviation.

Then ise the program geocol12, as in exercise 5. When asked (in the interactive mode) whether a grid is to be computed answer no (f), and answer yes (t) when asked if observations are to be compared with the computed values.

geocol12

GEODETIC COLLOCATION, VERSION 1 SEP 1991, RELEASE 2 (UNIX)
Thu April 5 12:34:28 1992

NOTE THAT THE FUNCTIONALS ARE IN SPHERICAL APPROXIMATION
MEAN RADIUS = RE = 6371 KM AND MEAN GRAVITY 981 KGAL USED.
MAX NUMBER OF OBS= 3200, MAX NUMBER OF PARAMETERS=239
MAX NUMBER OF OBS IN GIVEN REF. FRAME = 200
SIZE OF NORMAL EQ. BLOCKS=19800, SIZE OF POT.COFF. BLOCK= 130322
INTERACTIVE INPUT (T/F) t
INPUT: LTRAN, TRUE IF NON-STANDARD REF. SYSTEM IS USED
LPOT, TRUE IF SPHERICAL HARMONIC EXPANSION IS USED
LTEST, TRUE IF TEST-OUTPUT IS NEEDED
LLEG, TRUE IF LEGEND IS TO BE OUTPUT
LPARAM,TRUE IF PARAMETERS ARE TO BE DETERMINED
LNCOL, TRUE IF COLLOCATION IS NOT USED
LIOSOL,TRUE IF SOLUTION IS STORED OR RECOVERED
f t f f f t f
ARE ALL PARAMETERS OK ? t
INPUT CODE FOR BASIC REFERENCE SYSTEM:
0: USER DEFINED, 1: ED50 NORTH SEA, 2: ED50/EDOC,
3: NAD1927 /NEW MEXICO, 4: GRS67, 5: GRS80, 6: NWL9D,
7: BEST CURRENT, 8: BEST CUR. FAROE ISL, 9: ED50 FOR SF,
10: IAG-75, 11: KRASSOWSKY, DDR, 12: GERMAN DHDN, BESS.
5
REFERENCE SYSEM: GRS1980.

A = 6378137.00 M
1/F = 298.2572221
GM= 0.3986005000E+15
REF.GRAVITY AT EQUATOR = 978032.6772 MGAL
POTENTIAL AT REF.ELL. = 62636860.8500 M**2/SEC**2

INPUT NAME OF POT.COEFF. SET OSU91A TO DEGREE 20

SOURCE OF THE POTENTIAL COEFFICIENTS USED:
OSU91A TO DEGREE 360
INPUT: GM, SEMI-MAJOR AXIS (M), C(2,0), MAX. DEGREE
LFM, TRUE IF COEFF. IN INPUT STREEM AND *1.0D6
LBIN, TRUE IF ON BINARY FORM
LFORM, TRUE IF FORMAT IS INPUT
LINT, TRUE IF STORED AS INTEGERS
3.986005D14 6378136.2 0.0 20 f f t f
GM A COFF(5) MAX.DEGREE
0.39860050E+15 6378136.2 0.0000 360
INPUT FORMAT (2I4,2D18.0) F.EX. (2I3,2D19.12)
INPUT NAME OF FILE HOLDING COEFF.
/disk1/cct/cctf/osu91a1f
NAME OF FILE HOLDING COEFFICIENTS: osu91a1f
COEFFICIENTS UP TO N=5
2 0 -0.484165533E-03 0.000000000E+00
2 1 0.857179552E-12 0.289607376E-11
2 2 0.243815798E-05 -0.139990175E-05
3 0 0.957139401E-06 0.000000000E+00
3 1 0.202968777E-05 0.249431310E-06
3 2 0.904648671E-06 -0.620437817E-06
3 3 0.720295507E-06 0.141470959E-05
4 0 0.540441630E-06 0.000000000E+00
4 1 -0.535373285E-06 -0.474065010E-06
4 2 0.350729847E-06 0.663967363E-06
4 3 0.991080200E-06 -0.202148896E-06
4 4 -0.190576532E-06 0.309704029E-06

INPUT: LGRID - TRUE IF COMPUTATIONS IN A GRID
LERR - TRUE IF ERROR ESTIMATES ARE TO BE COMPUTED
OR REPRODUCED IN OUTPUT
LCOMP- TRUE IF COMPUTED VALUES ARE SUBTRACTED FROM OBSERVED
f f t
INPUT DATA LINE AND OUTPUT SPECIFICATIONS
POSITION OF STATION NUMBER (0: NO NUMBER, -1: NO OUTPUT U6)
POSITION OF LATITUDE AND LONGITUDE (E.G. 2 , 3)
TYPE OF ANGULAR UNITS USED (1: DD MM SS.S, 2: DD MM.M 3: DD.D)
POSITION OF HEIGHT (0: NO HEIGHT)
POSITION OF OBSERVATION 1 AND 2 (0 IF NO OBS. 1 OR 2)
DATA OR COMPUTATION QUANTITY TYPE CODE (11: GEOID,
13: GRAVITY, 15: TZZ, 26: (KSI,ETA), NEGATIVE: REF.SUBTR.)
COORD.SYST. CODE, -1 INDICATE GLOBAL SYSTEM, +100 REVERSE TR.
HEIGHT (IN M OR KM), ONLY USED IF NO INPUT HEIGHT
LPUNCH - TRUE IF OUTPUT OF RESULT TO FILE
LWLONG - TRUE IF LONGITUDE POSITIVE EAST
LMEAN - OBS. OR COMPUTED QUANTITY IS A MEAN VALUE
LSA - TRUE IF ALL ERROR ESTIMATES ARE IDENTICAL
LKM - TRUE IF HEIGHT IN KM
LADMU - TRUE IF UNREDUCED OR CONSTANTS * OR +
STAT - TRUE IF STATISTICS OF RESULT WANTED
LAREA - TRUE IF DATA ONLY INSIDE SPECIFIC AREA ARE USED
LFORM - TRUE IF FORMAT OF DATA IS INPUT
LIN4 - TRUE IF DATA NOT IN INPUT STREAM (FROM FILE)
LFORM - TRUE IF FORMAT OF DATA IS INPUT
LIN4 - TRUE IF DATA NOT IN INPUT STREAM (FROM FILE)
1 2 3 3 4 5 0 11 -1 0.0 t f f f f f t f f t
INPUT NAME OF FILE HOLDING DATA alt.e12
INPUT FORTRAN UNIT NUMBER 30

DATA INPUT FROM UNIT 30, FILE=alt.e12
INPUT NAME OF FILE TO HOLD RESULT alt.r20

SIMULTANEOUS OUTPUT TO FILE: alt.r20
INPUT SAMPLING INTERVAL SIZE 0.25
ALL SPECIFICATIONS OK ?

SELECTED GEOCENTRIC SYSTEM USED.
NO LATITUDE LONGITUDE H ZETA (M) POT
DEGREES DEGREES M OBS DIF
1970864 39.483500 -64.193100 0.0 -33.38 -2.65 -30.73

------ output from other observations not shown -----
-1
COMPARISON OF PREDICTIONS AND OBSERVATIONS
DATA TYPE = 11
NUMBER: 999
OBSERVATIONS PREDICTIONS DIFFERENCE
MEAN -32.22 -31.51 -0.70
ST.DEV. 0.98 0.80 1.11
DISTRIBUTION OF DIFFERENCES, UNITS: 0.25
23 58 69 73 78 76 82 71 68 76 61 69 42 33 51 20 20 9 4 1 0 15
-10 -9 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 OUTSIDE

STOP ? t

Type head alt.r20 to see the first lines of the output. Note the identification number, which tells the revolution number.

Data can then be contoured using geoplot21, as in other exercises. Answer t to the question on Contour plot. (Input example
in file /disk1/cct/geod/geoplot.ex12. This can be used after copying to your own directory.

/disk1/cct/dgeoplot/geoplot21 <geoplot.ex12 ).

When contouring try to use different interpolation methods.
Select one from the UNIRAS manual AGL/INTERPOLATIONS for a detailled description. Use contour interval 0.25 m.

The resolution used in the contour plot must also be given, measured in pixels. Start with a small number (e.g. 50 40) and later 150 x 120.

It is also possible to draw contours in a sub-area, called a REGION. This is not used her, so answer f when asked if a region is to be used.

For COLOR SCALE INDEX use 3 (blach/white), but other are possible see UNIRAS manual. As output-driver use MPOST or lx11 for screen output.
Last update 1999-05-11 by cct.