• View
• Edit
• History
• Print

	Title      EAST GREENLAND OBS SURVEY 2011
	By O.M.	Date 15 September 2015	Version 0.1

SURVEY, PROJECT DESCRIPTION

OBS-2011 trackline. Click to see large version. Map by A. Breivik.

GEOPHYSICAL EQUIPMENT

HSE

• Mini-streamer oil: MOBILECT-44

DATA

Profiles

¹⁾ This file contains data from both line 2 and 3. See GEODE log files for SP START/STOP.

Line 1 Mini-streamer geometry data

There are some extra/missing recordings in the SEGY file. Here is the error report:

# SP = 0013: Missing this SP in Geode log file
# SP = 0014: Missing this SP in Geode log file
# SP = 0015: Missing this SP in Geode log file
# SP = 0016: Missing this SP in Geode log file
# SP = 0017: Missing this SP in Geode log file
# SP = 0018: Missing this SP in Geode log file
# SP = 0019: Missing this SP in Geode log file
# SP = 0020: Missing this SP in Geode log file
# SP = 0021: Missing this SP in Geode log file
# SP = 0022: Missing this SP in Geode log file
# SP = 0023: Missing this SP in Geode log file
# SP = 0024: Missing this SP in Geode log file
# SP = 0025: Missing this SP in Geode log file
# SP = 0026: Missing this SP in Geode log file
# SP = 0027: Missing this SP in Geode log file
# SP = 0028: Missing this SP in Geode log file
# SP = 0029: Missing this SP in Geode log file
# SP = 0030: Missing this SP in Geode log file
# SP = 0031: Missing this SP in Geode log file
# SP = 0047: FFID step error, current = 122, previous = 120
# SP = 0091: FFID step error, current = 167, previous = 165
# SP = 0142: FFID step error, current = 219, previous = 217
# SP = 0159: FFID step error, current = 237, previous = 235
# SP = 0311: FFID step error, current = 390, previous = 388
# SP = 0471: FFID step error, current = 551, previous = 549
# SP = 0501: FFID step error, current = 582, previous = 580
# SP = 0626: FFID step error, current = 708, previous = 706
# SP = 0673: FFID step error, current = 756, previous = 754
# SP = 0873: Missing this SP in Geode log file
# SP = 0896: FFID step error, current = 980, previous = 978
# SP = 1065: Missing this SP in Geode log file
# SP = 1252: Missing this SP in Geode log file
# SP = 1287: FFID step error, current = 1372, previous = 1370
# SP = 1315: FFID step error, current = 1401, previous = 1399
# SP = 1338: FFID step error, current = 1425, previous = 1423
# SP = 1455: FFID step error, current = 1543, previous = 1541
# SP = 1485: FFID step error, current = 1574, previous = 1572

In order to set geometry in mini-streamer SEGY file we must first extract SP, FFID pairs from GEODE log file (GEODE is the recording system that collects data from the Mini-streamer), and afterwards merge this information with source positions given in the UKOOA P1/90 "QC" file

Download Mini-streamer geometry info file for Line 1. Easting/Northing coordinate pairs refer to UTM Zone 29W. NOTE: Source positions are used!

If you want to extract / merge other type of information, here is the Python script Δ that can be modified to suit your needs. It uses information in these two files:

• Line 1 Mini-streamer GEODE recording log file
• Line 1 UKOOA P1/90 QC file

The GEODE Mini-streamer recording system receives a nav data serial telegram from the survey computer for each shot point. This serial string is included in the GEODE log file, in lines containing the phrase "Received at". At the end of this line the FFID (SEGY record number) assigned to this particular telegram is stated. In this way we can tie a specific SP to its associated FFID in the SEGY file.

Example from GEODE log file. Survey computer nav data telegram in red. The PC inserts its own time stamp which is not synchronized to UTC, and hence discarded as we already know the correct SP time from the survey computer telegram.

  09:01:21 07.08.2011 497439.68 8042195.55    39 Data 703.0 N.A. - Received at 11:01:12.71 for File 113
    FFID     113 (Stack  1, Shot Loc: 0 Meters) 11:01:12.54 08/07/2011   33 KBytes SAVED IN 100.SGY
  09:02:39 07.08.2011 497365.81 8042009.79    40 Data 703.0 N.A. - Received at 11:02:30.71 for File 114
    FFID     114 (Stack  1, Shot Loc: 0 Meters) 11:02:30.57 08/07/2011   33 KBytes SAVED IN 100.SGY 

Transit data

The ship's survey computer software (Eiva NaviPac) merges data from the following four sources, and generates log files with 10 second sampling interval:

• Navigation system that provides time and position information
• Gravity meter
• Magnetometer ¹⁾
• Echo sounder (depth readings)

¹⁾ Magnetometer data is present ONLY while surveying ordinary profiles. So in transit data log files this parameter is set to zero.

Link to all transit files of this type.

GRAVITYMETER BASE READINGS

Summary

• Base readings in Bergen, 31 July 2011
• Gravitymeter: L & R, S/N: S-99
• S₉₉ = 0.xxxx

 Delta gabs = 
 Delta hw = 
 Delta av = 

 Drift rate = ( hw*0.3086 - S99delta av ) / delta tv

Base reading, 31 July 2011, Bergen

Still readings, gravitymeter S-99:

  -------------------------------------------------
   Day, time     DG       ST       CC   RAW     TC
  -------------------------------------------------
  212:11:52:00  13627.3  13627.3   0.0   -6    0.4

Measurements Nykirkekaien, Bergen:

Distance to sea surface: 1.80 m

Measurements Realfagbygget, reference point Seismo-lab:

Measurements Nykirkekaien, Bergen:

Distance to sea surface: 2.10 m

Still readings, gravitymeter S-99:

  -------------------------------------------------
   Day, time     DG       ST       CC   RAW     TC
  -------------------------------------------------
  212:13:33:30  13627.2  13627.3   0.0   -21   -0.2
  212:13:34:30  13627.3  13627.3   0.0   -19    0.0

Base reading, 21 August 2011, Longyearbyen

Ship's position: Nor-Cargo kaien ("Gamlekaia")

Still readings, gravitymeter S-99:

  -------------------------------------------------
   Day, time     DG       ST       CC   RAW     TC
  -------------------------------------------------
  233:06:39:20  14651.3  14651.2   0.0   14    -0.1
  233:06:40:50  14651.2  14651.2   0.0   20     0.3

Measurements Nor-Cargo kaien, Longyearbyen:

Distance to sea surface: 3.33 m

Measurements Nor-Cargo building, "reference point":

Measurements Nor-Cargo kaien, Longyearbyen:

Distance to sea surface: 3.40 m

Still readings, gravitymeter S-99:

  -------------------------------------------------
   Day, time     DG       ST       CC   RAW     TC
  -------------------------------------------------
  233:07:27:50  14651.3  14650.6   0.0    4     0.5
  233:07:29:00  14651.3  14650.6   0.0   14     0.6

Base reading, 30 August 2011, Longyearbyen

Ship's position: Nor-Cargo kaien ("Gamlekaia")

Still readings, gravitymeter S-99:

  -------------------------------------------------
   Day, time     DG       ST       CC   RAW     TC
  -------------------------------------------------
  242:13:41:00  14648.8  14648.7   0.0   -3    -0.1

Measurements Nor-Cargo kaien, Longyearbyen:

Distance to sea surface: 2.85 m

Measurements Nor-Cargo building, "reference point":

Measurements Nor-Cargo kaien, Longyearbyen:

Distance to sea surface: 3.40 m

Still readings, gravitymeter S-99:

  -------------------------------------------------
   Day, time     DG       ST       CC   RAW     TC
  -------------------------------------------------
  242:14:19:30  14648.9  14648.7   0.0   -6     0.1

K-check, 31 July 2011

 ST OFF
  Slew ST +30.0, wait > 5 min. -> TC = -30.3
 ST ON

 MARINE OPERATING SYSTEM: 1.12
 FOR METER S-99 (w/ FOG pack)

UKOOA P1-90 NAV DATA FILES

UTM Zone, reference point on vessel

All UTM data are relative to UTM Zone 27.

All coordinates are also relative to the position of the gravitymeter onboard the ship.

Gravitymeter is placed at frame 40.

Frame distance is 0.6 m. Thus, gravitymeter is 40 x 0.6 m = 24.0 m from the stern.

Airgun offset distance

Airguns are positioned 48 meter behind the stern.

We have to add offset between gravitymeter and stern, to obtain the total offset between source and positions given in navdata files.

Thus, total offset between source and positions given in nav data files is: 48 m + 24.0 m = 72.0 m.

UKOOA P1/90 navdata format

Output from nav data processing should be in UKOOA P1/90 format, slightly modified to accomodate three decimals in time value.

The UKOOA P1/90 format specification can be downloaded from SEG. It's a fixed-position format without any <SPACE> or <TAB> delimiters between fields, so it can be hard to read. However, by inserting appropriate comment field in the header, it can be made much more legible, as this example shows. The first part is the header; the individual shotpoints are at the end (six lines) :

   H0100 SURVEY AREA ISFJORDEN, SVALBARD
   H0101 SURVEY DETAILS SVALEX-2005
   H0102 VESSEL DETAILS R.V. HAAKON MOSBY
   H0104 STREAMER DETAILS 240 CH GECO NESSIE-3
   H0200 SURVEY DATE AUGUST - SEPTEMBER 2005
   H0201 FILE CREATED 16-Jan-2006
   H0202 FILE VERSION UKOOA P1/1990
   H0300 CLIENT SVALEX-2005
   H0400 GEOPHYSICAL CONTRACTOR UNIVERSITY OF BERGEN, NORWAY
   H0500 POSITIONING CONTRACTOR N/A
   H0600 POSITIONING PROCESSING O.M. UNIVERSITY OF BERGEN, DEPT OF EARTH SCIENCE
   H0700 POSITIONING SYSTEM
   H0700 SURVEY COMPUTER SOFTWARE NAVIPAC, EIVA, DENMARK
   H0700
   H0800 SHOTPOINT POSITION CENTRE OF SOURCE
   H1000 CLOCK TIME UTC
   H0900 OFFSET SHIP SYSTEM TO SP 70.0 M BEHIND
   H1200 SPHEROID AS SURVEYED A,1/F WGS-84 Spheroid 6378137.000 298.2572236
   H1300 SPHEROID AS PLOTTED A,1/F WGS-84 Spheroid 6378137.000 298.2572236
   H1400 GEODETIC DATUM AS SURVEYED WGS-84
   H1500 GEODETIC DATUM AS PLOTTED WGS-84
   H1700 VERTICAL DATUM SL : ECHO SOUNDER
   H1800 PROJECTION 001 UTM NORTHERN HEMISPHERE
   H1900 ZONE 33X NORTHERN HEMISPHERE
   H2000 GRID UNIT 1 METRE
   H2001 HEIGHT UNIT 1 METRE
   H2002 ANGULAR UNITS 1 DEGREES
   H2200 CENTRAL MERIDIAN 15 DEG E
   H2600
   H2600 00011111111112222222222333333333344444444445555555555666666666677777777778
   H2600 78901234567890123456789012345678901234567890123456789012345678901234567890
   H2600 -NAME-><->---<-SP-><---LAT--><--LONG---><--EAST-><-NORTH-><-DEP><D><TIME>-
   SLine34-05             18781022.23N 141348.31E 482384.58677774.7 215.8242180734
   SLine34-05             19781023.47N 141353.32E 482416.98677812.8 214.7242180755
   SLine34-05             20781024.73N 141358.24E 482448.78677851.4 212.3242180816
   SLine34-05             21781026.00N 1414 3.08E 482480.08677890.4 209.6242180837
   SLine34-05             22781027.28N 1414 7.88E 482510.98677929.7 207.6242180858
   SLine34-05             23781028.53N 141412.83E 482543.08677968.1 206.2242180919

UKOOA P1-90 navdata format structure.

The shotpoint (SP) parameter, for instance, is located from column 20 to 25, as shown below. The two colomn numbering lines, together with the parameter name line, is an aid in determining the colomn position of the different parameters. These three "assist" lines are not common - they are only inserted by the software we use to generate UKOOA P1/90 files.

  +--------> Column 20
  |
  |    +---> Colomn 25
  |    |
  222222
  012345
  <-SP->
      18
      19
      20
      21
      22
      23

"OBS" modification of UKOOA P1/90 navdata format

OBS refraction surveys means that source (airguns on ship) and receivers (OBS placed on the bottom, or on land, as an extension of the profile) must maintain a common, accurate - to the nearest millisecond - time base. This is accomplished by special oven-controlled oscillators in the OBS instruments, and GPS locked clocks in land based instruments. On board the ship, the exact time of the shotpoint is recorded by two time-tagging systems operating in paralell (details provided in table of geophysical equipment above).

The time field in the UKOOA P1/90 format only accomodates seconds without decimals. The format has been modified to permit storage of shot times with six decimal places, of which only the three most significant decimals are used.

An example of modified file:

   H2600 FILE FORMAT MODIFIED TO INCLUDE SHOTPOINT TIME IN COLUMNS [7..19]
   H2600
   H2600 00011111111112222222222333333333344444444445555555555666666666677777777778
   H2600 78901234567890123456789012345678901234567890123456789012345678901234567890
   H2600 <--SP TIME--><-SP-><---LAT--><--LONG---><--EAST-><-NORTH-><-DEP><D><TIME>-
   SSM-1 101921.956000     1632728.92N  74033.97E 732982.37045135.6 171.3297101921 
   SSM-1 102109.690000     2632728.28N  74019.50E 732783.87045101.1 172.4297102109 
   SSM-1 102251.455000     3632728.66N  740 5.07E 732583.57045098.3 176.4297102251 

"EIVA" Survey Computer shot event log files

The format of these shotpoint logfiles is as follows:

 Event       Date         Time    Easting    Northing St.d.  Gyro      Dal    Dol      Kp    Object    Data
 -----------------------------------------------------------------------------------------------------------
 000057 2010.06.02 02:51:41.914 0334654.77 07118140.71 00.90 038.1 00000.15 005.14 000.000 "H Mosby f " 3002.22 9449.08 52045.27 "" 01
 000058 2010.06.02 02:52:59.662 0334792.73 07118285.63 00.80 037.7 00200.24 005.27 000.200 "H Mosby f " 3010.88 9448.82 52040.90 "" 01
 000059 2010.06.02 02:54:19.285 0334928.16 07118432.47 00.80 037.6 00399.98 002.25 000.400 "H Mosby f " 3019.18 9449.93 52035.06 "" 01
 000060 2010.06.02 02:55:36.205 0335067.61 07118575.91 00.70 037.9 00600.02 004.48 000.600 "H Mosby f " 3027.67 9451.44 52025.12 "" 01

Parameters are given in first line. Most are self-explanatory, except these:

Gyro

Heading of ship (which could be different from the course the ship is following, due to current or wind direction).

Dal

Distance Along Line. NOTE: This is distance along current line SEGMENT, where new segment start at position of each OBS.

Dol

Distance Off Line (deviation from course line - we have manual steering of vessel).

Kp

Kilometer Post - total distance covered along the line.

Object

Description of Survey Computer navigation data handling. Complete text is not included in log file; it should read "H Mosby filtered", meaning that GPS positions (incl. differential corrections) are subjected to a filtering algorithm (Kalman).

Data

Data values, delineated by "", selected by Eiva Survey Computer operator; in this case Depth (from Simrad EK60 Echo Sounder onboard), Gravity and Magnetometer.

The last item in ech line ("" 01) can be ignored.

Shot timestamp files

Time values in files generated by University of Bergen timestamp unit is given in UTC.

 $PUIBR,TTT,,02:51:42.7163,5595,7812*00
 $PUIBR,TTT,,02:53:00.4707,3677,7812*00
 $PUIBR,TTT,,02:54:20.0914,714,7812*00
 $PUIBR,TTT,,02:55:37.0041,32,7812*00

Parameters are comma delimited. Record structure mimics NMEA GPS telegram format. Using first line as example, parameters are:

Field #1 - $PUIBR

Telegram header. By convention, "P" stands for "proprietary" (meaning not covered by the standard). "UIB" = University of Bergen.

Field #2 - TTT

Time tag identifier

Field #3 -'''

Empty

Field #4 - 02:51:42.7163

Event time stamp, in UTC. Four fractional digits.

Field #5 - 5595

Internal housekeeping data: Event occured at this Timer0 interrupt value. Interpolated event time is then the ratio between this number, and the number in field 6.

Field #6 - 7812

Internal housekeeping data: Number of CPU Timer0 interrupts last second. This number should be constant. It indicates the smallest time resolution interval: 1/7811Hz = 128.0 µseconds

SOME IMAGES FROM LONGYEARBYEN

• Link to album