Recent Changes - Search:

Top

Marine gravitymeter, S-99

Land gravitymeter, G-936

Data format, conversion

Air/Sea operation

Base readings

Data processing

Projects

Other information

edit SideBar

September 22, 2022, at 07:44 AM
Version: pmwiki-2.3.22

RV "G.O. SARS 2008: LINE SELECTION


This is a continuation of previous processing of data from this survey.

Survey details Vessel: RV "G.O. SARS"
Start: 29 June 2008, Tromsø
Finish: 19 July 2008, Tromsø
P.I. Prof. Dr. Rolf Birger Pedersen
Dept. of Earth Science
University of Bergen, Norway
Data pre-processing, part B O. Meyer
Depth of Earth Science
University of Bergen, Norway
Date: 15 Feb. 2010

INTRODUCTION


We want to select some lines for further gravity processing. This report details the identification of possible candidates.

T. Svendsen plotted candidate lines, and extracted relevant sample data to file. White lines on map below shows these possible lines.

SARS-2008 survey lines
RV "G.O.SARS" 2008 survey lines - white ones candidates for further gravity processing" (map: T.S)

INPUT FILE


This file contains list of 10 second gravity values, including time- and position stamping.

All candidate lines are included in one file.

Excerpt:


LINE1

1214942640,01.07.2008,200400,73.380018506,8.887070837,2415.2,10032.91
1214942650,01.07.2008,200410,73.379587858,8.887253941,2415.2,10032.93
1214942660,01.07.2008,200420,73.379156183,8.887189275,2415.2,10032.95
...
1214965300,02.07.2008,022140,73.808221948,6.792030334,2974.4,10089.14
1214965310,02.07.2008,022150,73.808439438,6.791287059,2973.1,10089.19
1214965320,02.07.2008,022200,73.808676574,6.790616242,2972.2,10089.24


LINE2

1214966220,02.07.2008,023700,73.828875631,6.834000062,2985.2,10072.08
1214966230,02.07.2008,023710,73.828712652,6.834995784,2985.8,10072.12
1214966240,02.07.2008,023720,73.828551297,6.836000340,2986.5,10072.15
1214966250,02.07.2008,023730,73.828387949,6.837011705,2987.1,10072.17
...

Parameter description:

  1. Standard Unix time stamp [seconds since 01.01.1970, 00:00:00]
  2. Date [dd.mm.yyyy]
  3. Time [hhmmss]
  4. Latitude [decimal degrees]
  5. Longitude [decimal degrees]
  6. Depth [m]
  7. Gravity value

PROCESSING


As first stage in line selection, we want to plot ship speed for all lines. After that we will decide which line (or part of each) that is suitable for further processing.

This is achieved by:

  • Converting LAT/LONG coordinates to UTM and calculating distance between each sample point, and using this value to obtain ship's speed.
  • Generate output files, one for each line. Parameter description in top of file.
  • For each line, plot ship speed as function of time.

An external library is used for LAT/LONG to UTM conversion.

Processing software (first part consists of LAT/LONG conversion library):

RESULTS


Click image below to see all plots:

Edit - History - Print - Search
Page last modified on November 28, 2012, at 12:55 PM
Electronics workshop
Department of Earth Science - University of Bergen
N O R W A Y