MIRAI MR17-05C Shipboard Three Component Magnetometer (STCM)

Last Modified: 2019-06-21
: MR17-05C
: 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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2017-08-24 00:19 – 2017-09-30 22:30

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.
Data quality is not correct because machine trouble.
Date (UTC)
2017/09/05  20:38 - 2017/09/06  01:21
2017/09/08  23:26 - 2017/09/09  02:05
2017/09/09  15:35 - 2017/09/09  16:05
2017/09/18  20:10 - 2017/09/19  00:45
2017/09/20  02:25 - 2017/09/20  04:00
2017/09/25  22:56 - 2017/09/26  02:04
2017/09/26  22:46 - 2017/09/27  00:09
2017/09/27  04:17 - 2017/09/27  05:29
2017/09/27  06:32 - 2017/09/27  08:08
2017/09/28  09:45 - 2017/09/28  10:42
2017/09/29  23:23 - 2017/09/29  23:34
2017/09/30  07:59 - 2017/09/30  10:57
  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

In MR17-05C cruise
Date (UTC)
2017/08/26 17:00:00 - 2017/08/26 17:24:00
2017/09/20 12:34:00 - 2017/09/20 12:55:00
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 12th 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
  | 0.9985 0.0217 0.0353 |   | 1992.9973 |
B = | -0.0287 1.0627 -0.0244 | Hbp = | 1033.1324 |
  | 0.0312 0.0042 0.8233 |   | 8814.2788 |
(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.
: MR17-05C
: 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
MR17-05C_corr.stcm
: MR17-05C
: 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.
2018-06-01
An observation data was registerd.
2018-05-29
An observation data was registerd.