MIRAI MR12-05 Leg3 Shipboard Three Component Magnetometer (STCM)

Last Modified: 2019-06-21
: MR12-05 Leg3
: Processed (DMO)-Corrected
: JAMSTEC
: X, Y and Z component of geomagnetic field anomaly, Absolute value of geomagnetic field anomaly
:
OCEANS > MARINE GEOPHYSICS > MARINE MAGNETICS
SOLID EARTH > GEOMAGNETISM

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2013-01-07 02:06 – 2013-02-13 11:59

Instrument:
Three component magnetometer
The data provided is for corrected three component geomagnetic field anomalies. Three-axes flux-gate sensors with ring-cored coils were fixed on the roof of the bridge.
They measure the following items :
h-component : along track line component, positive for the bow direction pitch.
s-component : across track line component, positive for the starboard side roll.
v-component : vertical component, positive for the downward direction.
The effect of ship motion was eliminated by roll and pitch data which was provided by a tilt sensor. The apparent magnetic influence can be detected through a "Figure of 8 turn"(a pair of clockwise and anti-clockwise turns) on each cruise. If no Figure of 8 turn on the cruise was completed, the latest Figure of 8 turn from the previous cruise was applied. As a quality control, data of low reliability was removed (see Data processing for quality control criteria). Synthetic geomagnetic field values were calculated from IGRF models.
  1. (1) Magnetometer
  2. Manufacturer : Tierra Technica Ltd.
    Type : SFG1214
    Measurement range : ±100,000 nT
    Accuracy : less than 100 nT
    Resolution : 1 nT
    Location : Dry Laboratory

  3. (2) Magnetic Sensor
  4. Manufacturer : Tierra Technica Ltd.
    Form : flux-gate sensors with ring-cored coils
    Location : Foremast

  5. (3) Attitude sensor and Gyro compass
  6. Manufacturer : IXBLUE
    Type : PHINS
    Accuracy(Roll, Pitch) : 0.01 degree
    Accuracy(Gyro) : 0.01 degree *Secant(Lat.)
    Location : In the doppler radar dome

On this cruise
Date (UTC)
2013/01/24 11:12:00  - 2013/01/24 11:37:00
2013/02/02 15:24:00  - 2013/02/02 15:54:00
2013/02/09 00:03:00  - 2013/02/09 00:28:00
2013/02/13 07:02:00  - 2013/02/13 07:29:00
The following corrections and calculations were performed.

(1) Ship magnetization correction
   Hob = ARPYF + Hp ---(i)
  Hob: Observed magnetic field vector (Ship coordinates)
  A: Effect of induced magnetization of the ship
  R: Matrix of rotation due to the roll
  P: Matrix of rotation due to the pitch
  Y: Matrix of rotation due to the heading
  F: Geomagnetic field vector
  Hp: Ship's permanent magnetic moment

Following the equation(i), we calculate the geomagnetic field F.
    RPYF = BHob + Hbp ---(ii)
  B: coefficient of Figure of 8 turn
  Hbp: Permanent magnetic field vector of the ship

Reference: Isezaki,N., A new shipboard three-component magnetometer, GEOPHYSICS. VOL.51,NO10(1986);P1992-1998

(2) International Geomagnetic Reference Field (IGRF)
  Synthetic geomagnetic field values are calculated from IGRF 11th Generation models by using navigation data ; latitude, longitude and date.
  Reference:IAGA Division V-MOD Geomagnetic Field Modeling[http://www.ngdc.noaa.gov/IAGA/vmod/igrf.html]

(3) Calculation of the geomagnetic field anomaly
    An = F - Figrf
  An: Geomagnetic field anomaly vector
  F: Geomagnetic field vector
  Figrf: Synthetic geomagnetic field vector from IGRF

(4) Quality control of data
  Following criteria were used for removal of data of low reliability:

      ・Time error (inversion of time, continuation of same timestamps)

      ・Summation of the difference of heading by one second exceeding 20 degree per 5 minutes

      ・Ground speed of the ship below 3knot or exceeding 20knot

      ・X, Y, or Z component of geomagnetic field anomaly exceeding ±4000nT

(5) Filtering of the geomagnetic field anomaly
  Due to the residual undulation of the ship, a 120 second length Gaussian filter was applied for each component of the geomagnetic field anomaly data.

(6) Output of the data
  Time (UTC)
  Latitude (degree)
  Longitude (degree)
  X: Northward (positive on the north) component of geomagnetic field anomaly (nT)
  Y: Eastward (positive on the east) component of geomagnetic field anomaly (nT)
  Z: Vertical (positive for downward) component of geomagnetic field anomaly (nT)
  T: Absolute value of geomagnetic field anomaly (nT)
This coefficient was calculated from the above-mentioned Figure of 8 turn
  | 0.9905
0.0594
0.0331
|   | 2154.1352
|
B = | -0.0634
1.0549
-0.0022
| Hbp = | 49.0126
|
  | 0.0375
0.0053
0.9712
|   | 2612.2355
|
(1) File naming rule: Cruise ID_corr.stcm
(2) Sampling rate: 10 seconds
(3) Geodetic system: WGS84
(4) If you would like the raw data set, please contact us from "Contact Us" above.
: MR12-05 Leg3
: Processed (DMO)-Corrected
: JAMSTEC
: X, Y and Z component of geomagnetic field anomaly, Absolute value of geomagnetic field anomaly
:
OCEANS > MARINE GEOPHYSICS > MARINE MAGNETICS
SOLID EARTH > GEOMAGNETISM

Observation Map

Imagery reproduced from ...

Figures

Data List

  File names
MR12-05_leg3_corr.stcm
: MR12-05 Leg3
: Processed (DMO)-Corrected
: JAMSTEC

STCM Corrected

No. Column Content Format Unit Remarks
1 1 - 8 Date i4,i2,i2 YYYYMMDD (UTC)
2 10 -15 Time i2,i2,i2 hhmmss (UTC)
3 17 -25 Latitude f9.5 degree No sign for the northern hemisphere.
Negative for the southern hemisphere.
4 27 -36 Longitude f10.5 degree No sign for eastern hemisphere.
Negative for the western hemisphere.
5 38 -43 X component of geomagnetic field anomaly f6.0 nT Positive on the north
6 45 -50 Y component of geomagnetic field anomaly f6.0 nT Positive on the east
7 52 -57 Z component of geomagnetic field anomaly f6.0 nT Positive for downward
8 59 -64 Absolute value of geomagnetic field anomaly f6.0 nT

Related Information

Update History

2019-06-21
An observation data was registerd.
2018-04-18
An observation data was registerd.
2014-08-12
An observation data was registerd.
2013-08-30
An observation data was registerd.