- Data format difference between
high-resolution and marine mode
- May 20, 2003: Base reading Dokken, Bergen
- June 2, 2003: Base reading Bodoe
- June 30, 2003: Base reading Marineholmen, Bergen
- Land gravitymeter calibration table
Referring to the UltraSys format description dated June 14, 1999: http://www2.geo.uib.no/gravitymeter/ultrasys-data-formats.html
Gravity data on this survey was logged in high-resolution mode - normally, marine mode should be used. Be aware of
the gravity data format difference between high-resolution and marine mode.
The hard disk data has the same structure in both these cases:
EXAMPLE:
IIIIIIIIIIYYYYDDDHHMMSSGGGGG.GGSSSSS.SSCCCC.CCBBBBBB.BVVVVVVV.
LLLLLLL.XXXXXXX.#######.-------------etc---------#######.HHHHHHHH
PPPPP.AAA.AAA---etc----AAA.AAA.
The important detail is the gravity value (GGGGG.GG) which in marine mode is given in mGal or counter units, as
selected by the operator. In high-resolution mode, the gravity value is always given in counter units, updated at 10 sec
intervals. But the "Video Gravity Display" will give gravity in mGal units - independant of mode setting.
- Scans of log book: 1. page, 2. page
- Time: 20:20 UTC
- Still reading marine gravitymeter, from video display:
| Day of year : HH :MM |
Gravity, from video display
[mGal] |
Spring tension
[Counter units] |
Cross coupling
[Counter units] |
Raw beam
[mV] |
Total correction
[Counter units] |
| 140:20:06 |
11968.4 |
11968.5 |
0.0 |
4.0 |
0.1 |
| 140:20:15 |
11967.5 |
11967.0 |
0.0 |
4.0 |
0.6 |
| 140:20:34 |
11967.2 |
11967.0 |
0.0 |
-1.0 |
0.0 |
Sketch of area:
Fig 1. May 20, 2003, base reading Dokken, Bergen: Location
Tying Dokken to Gravity station in Realfagsbygget, Bergen
| Location |
Land gravitymeter reading
(Refer to handbook for conversion to mGal) |
Time
(Local time) |
Date |
| Realfagbygget, Bergen |
5392,125 |
13:22 |
Oct. 20, 2004 |
| -- :: -- |
5392,215 |
13:34 |
-- :: -- |
| -- :: -- |
5392,180 |
13:40 |
-- :: -- |
Dokkeskjaerskaien, bollard no. 167
(labelled no. 10 on side that faces the sea) |
5395,941 |
14:16 |
-- :: -- |
| -- :: -- |
5395,912 |
14:20 |
-- :: -- |
| -- :: -- |
5395,979 |
14:23 |
-- :: -- |
| -- :: -- |
5395,950 |
14:25 |
-- :: -- |
| Check, Realfagbygget, Bergen |
5392,108 |
14:54 |
-- :: -- |
| -- :: -- |
5392,205 |
14:57 |
-- :: -- |
| -- :: -- |
5392,190 |
14:59 |
-- :: -- |
Sketch of location:
Fig 2. June 2, 2003, base reading Bodoe: Location
Unfortunately, there are no land gravitymeter ties to the nearest gravity station,
in the harbour area approx. 300 m from where the ship was moored.
A decision must be made re. the possibility of tying the still reading directly to the gravity station, based on the short distance between
the ship and the nearest gravity station.
- Scans of log book: page
- Day of year: 181
- Time: 08:45 UTC
- Still reading marine gravitymeter, from video display:
| Day of year : HH :MM |
Gravity, from video display
[mGal] |
Spring tension
[Counter units] |
Cross coupling
[Counter units] |
Raw beam
[mV] |
Total correction
[Counter units] |
| 181:08:41 |
11956.6 |
11956.3 |
0.0 |
6.0 |
0.4 |
| 181:09:05 |
11956.6 |
11956.3 |
0.0 |
2.0 |
0.3 |
| 181:09:25 |
11956.5 |
11956.3 |
0.0 |
-2.0 |
0.1 |
Sketch of location:
Fig 3. June 30, 2003, base reading Marineholmen, Bergen: Location
Tying Marineholmen to Gravity station in Realfagsbygget, Bergen
| Location |
Land gravitymeter reading
(Refer to handbook for conversion to mGal) |
Time
(Local time) |
Date |
| Realfagbygget, Bergen |
5392,360 |
11:01 |
Nov. 3, 2004 |
| -- :: -- |
5392,310 |
|
-- :: -- |
| -- :: -- |
5392,323 |
|
-- :: -- |
Marineholmen, close to bolland
shown in fig. 3 |
5394,380 |
11:24 |
-- :: -- |
| -- :: -- |
5394,380 |
|
-- :: -- |
| -- :: -- |
5394,395 |
|
-- :: -- |
| Check, Realfagbygget, Bergen |
5392,320 |
11:55 |
-- :: -- |
| -- :: -- |
5392,275 |
|
-- :: -- |
| -- :: -- |
5392,338 |
|
-- :: -- |
Converting dial readings to mGal values, from land gravitymeter manual (click image to enlarge):
|
