URASHIMA URSM 00090 Submersible Conductivity-Temperature-Depth Profiler (CTD)

Last Modified: 2018-09-30
: URSM 00090
: Processed (DMO)-QCed
: Depth/Pressure, Temperature, Salinity

For Using Data

Data Management Office
See Terms and Conditions about constrain of use.
See Terms and Conditions about data citation.
  The CTD system mounted on the deep-sea cruising vehicle "URASHIMA" is consisted of SBE-49 FastCAT CTD Sensor of Sea-Bird Electronics, Inc. The primary detection element is installed vertically on the front center part of the vehicle. Its withstand depth is 7000m and its maximum depth of use is 3500m. Each parameter of conductivity, water temperature, and pressure can be measured in 1Hz and is transmitted to the CTD processing part. In the processing part, ASCII conversion is conducted.
  SBE-49 FastCAT, Sea-Bird Electronics, Inc.
Sensor Measurement range Accuracy Model
  Temperature    -5 to +35 deg-C    0.002 deg-C    SBE 49 
  Conductivity    0 to 9 S/m    0.0003 S/m 
  Pressure    0 to 10000 psia    0.1% of full scale range 
  The data collection in each dive starts from the moment of operation confirmation on deck and ends immediately after it comes up to the sea surface.
  The primary detecting element is installed on about the same height of the pressure gauge.
  The seawater intake mouth projects from a crust in a plastic tube to lower influence of the disorder of the seawater  with the vehicle.
  The internal clock of CTD is synchronized, in each dive, with "URASHIMA" NTP server.
  The data available on this web site is 1-sec mean CTD data integrated with "URASHIMA" (hereafter, the submersible vehicle) positioning data in latitude and longitude. The SSBL (Super Short Base Line) method is used to measure the submersible vehicle's position, which requires transponder mounted on the submersible vehicle and an array of transducers equipped on the bottom of the mother ship. The position is measured by both phase lag measured from angles of received sound waves and distance calculated from travelling period of them. Because the baseline length (i.e., a distance between transducers and the transponder) is short, a horizontal error is about 2.5% of slant range (i.e., a distance between the submersible vehicle and the mother ship). The SSBL method has a characteristic that it is a little less accurate but easier to operate than the LBL (Long Base Line) method because it doesn't need to deploy sea-bed mounted transponder(s). Vertical profile of sound velocity is needed to calculate accurate distance from the travelling period. Therefore, the temperature measurement using XBT etc. of each sea area is executed.
  The submersible vehicle positioning data was calculated by adding the relative distance to the mother ship's position. The simplified equation with the area-dependent coefficients every 30 degrees in latitude and longitude was applied to the distance (XY) to Lon/Lat conversion, which provided by Japan Coast Guard. Here, the original time interval of position data is more than 10 seconds. The noises remaining in the position data are manually eliminated and linearly interpolated when the speed calculated from adjacent two position data is greater than 4 knot which is the maximum operation speed of the submersible vehicle. Moreover, noises remained in the depth, temperature, and salinity data are visually checked and replaced to missing values only when the data seemed to be obviously abnormal.
  The CTD system was installed as one of the navigation equipment to monitor the ambient environmental conditions of the submersible vehicle, of which sensor calibration is normally executed about every two years.
  After considering the accuracy of the sensors, the significant digit of data was changed as in the following list.
Data Raw On this web site
Pressure 0.001 [dbar] 0.1 [dbar]
Temperature 0.0001 [deg-C] 0.01 [deg-C]
Salinity 0.0001 [PSU] 0.01 [PSU]

: URSM 00090
: Processed (DMO)-QCed
: Depth/Pressure, Temperature, Salinity

Observation Map

Imagery reproduced from ...


Data List

  File names
: URSM 00090
: Processed (DMO)-QCed

Submersible CTD Qced (URSM)

  1. Header part
No. Column Item Format Remarks
1 1 Header ID a1 fixed as '#'
2 3 - 37 Submersible vehicle a35 URASHIMA
3 39 - 48 Data ID a10 CTD
4 50 - 70 Cruise ID a21 YKYY-XX(_legx)
5 78 - 81 Dive number a4
  1. Data part
No. Column Item Unit Format Remarks
1 1 - 8 Date - i8 YYYYMMDD (LST)
2 10 - 15 Time - i6 hhmmss (LST)
3 17 - 26 Latitude degree f10.5 No sign for the northern hemisphere.
Negative for the southern hemisphere.
4 28 - 37 Longitude degree f10.5 No sign for the eastern hemisphere.
Negative for the western hemisphere.
5 39 - 48 Pressure dbar f10.1
6 50 - 59 Temperature deg-C f10.2 ITS-90
7 61 - 70 Salinity PSU f10.2 PSS-78
8 72 - 81 Dissolved oxygen ml/l f10.1
9 83 - 92 Altitude m f10.1
10 94 - 103 Roll degree f10.1
11 105 - 114 Pitch degree f10.1
12 116 - 125 Vehicle heading degree f10.1
  1. Missing value is presented by '-999'.

Related Information

Cruise Data Dive Data

Update History

An observation data was registerd.