CTD Manual

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CTD
Deployment

CTD casts are be made at each station. Casts are to within 5 meters of the bottom. Bottom depth will is determined by both CTD depth transducer and ship-board depth indicators. Depending on bottom depth, casts will vary from 10 to 20 minutes. Deployment is off the stern and requires assistance of at least one deck-hand. On the up-cast, the winch operator will be asked to stop at predetermined depth intervals to obtain a water sample. The ship’s seacable will need to have both a mechanical and electrical termination. Electrical termination should be a female, high-pressure, four-pin connector.

The CTD, once in the water, should be lowered to 10m and allowed to equilibrate (approx. 2 minutes). Once equilibrated the unit should be brought back to the surface and then the cast begun.

Data Processing

CTD data is processed following the routine outline in the Seabird Seasoft manual. The data processing procedure is outlined below.

Copy files from the CTD/PRR laptop to the PC MooMoo. Files should be copied to c:\pnb\ctd\con6\.

Delete the *.con files.

Edit each *.bl file so that the appropriate path appears in the header.

C:\pnb\ctd\con6\`file_name’

Start Seasave.exe

Select Display Archived Data

Make sure the correct calibration file and paths are set.

Current calibration file is: 217_6.CON

Path should be: C:\PNB\CTD\CON6

Select the first file in the list.

Under Number of Scans to Skip Over: Enter 0.

Display the file. Note the number of scans for the initial equilibration downcast. Exit the display.

Under Number of Scans to Skip Over: Enter the number of scans for the initial equilibration downcast. Redisplay the file. Repeat this procedure until the all scans from the initial equilibration downcast are removed. Be sure to note the number of scans to skip.

Repeat this procedure for all files.

Exit Seasave

Start Datcnv.exe

Make sure correct calibration file and paths are set.

Check all settings

DATCNV Format=Ascii

DATCNV Variables:

Coversion Units: Metric

Column #0=scan number

Column #1=time [julian days]

Column #2=pressure [db]

Column #3=descent rate [m/s]

Column #4=beam attenuation coefficient

Column #5=conductivity [S/m}

Column #6=light transmission

Column #7=fluorometer, sea tech

Column #8=irradiance (PAR)

Column #9=voltage, number 0 [V]

Column #10= voltage, number 1 [V]

Column #11= voltage, number 5 [V]

Column #12=temperature IPTS-68 [deg C]

Column #13=temperature IPTS-90 [deg C]

Columns #14-29=none

Output Cast Select = Both Down Cast and Up Cast

Output Water Bottle Data = Yes

Water Bottle Data Set Up:

Output File Select = Create Both .CNV and .ROS Files

Source of Scan Range:

Bottle Log File [.BL]

Input File [.BL]:

Enter Appropriate File

Offset (seconds) = 0

Duration (seconds) = 3

Press ESC until the DATCNV Set Up screen appears.

Enter the appropriate number of scans to skip.

Press F10. Select: Output to the File.

Check that all file names are consistent for both input and output files.

Repeat this procedure for all files.

Exit Datcnv.exe

Start process_911.bat

Filter Selection Form

Check values:

Low Pass Filter A, Time Constant [sec] = 0.15

Low Pass Filter B, Time Constant [sec] = 0

Variables to Filter:

Filter, pressure [db] = Low Pass Filter A

All others = none

Press ESC until the Filter Selection Form screen appears. Press F10

CELLTM Set Up

Check values:

Thermal Anomaly Amplitude (Alpha) = 0.03

Thermal Anomaly Time Constant (1/beta) = 7.0

Press F10

LOOPEDIT Set Up

Check values:

Minimum Velocity Selection = Fixed Minimum Velocity

Minimum CTD Velocity [m/s] = 0.25

Exclude Scans Marked Bad In LOOPEDIT = Yes

Press F10

BINAVG Set Up

Check Values

Bin Type = pressure bins

Bin Size = 1.0

Include Number of Scans Per Bin = No

Exclude Scans marked Bad in BINAVG = Yes

Number of Scans to Skip Over = 0

Surface Bin Set Up Parameters:

Include Surface Bin = No

Surface Bin Minimum Value = 0

Surface Bin maximum Value =0

Value For Surface Bin (Default=0) = 0

Press ESC until the BINAVG Set Up screen appears. Press F10.

DERIVE Set Up

Check Values:

Input Variables:

Variable #0=scan number

Variable #1=time [julian days]

Variable #2=pressure [db]

Variable #3=descent rate [m/s]

Variable #4=beam attenuation coefficient

Variable #5=conductivity [S/m}

Variable #6=light transmission

Variable #7=fluorometer, sea tech

Variable #8=irradiance (PAR)

Variable #9=voltage, number 0 [V]

Variable #10= voltage, number 1 [V]

Variable #11= voltage, number 5 [V]

Variable #12=temperature IPTS-68 [deg C]

Variable #13=temperature IPTS-90 [deg C]

Variables to be Derived:

Variable #0=density, sigma-theta [kg/m3]

Variable #1=density, sigma-t [kg/m3]

Variable #2=potential temperature IPTS-68 [deg C]

Variable #3= potential temperature IPTS-90 [deg C]

Variable #4=salinty, PSS-78 [PSU]

Variable Coefficients:

Time Window Size for doc/dt [s] = 2.0

Time Window Size for Descent Rate and Accel. [s] = 2.0

Press ESC. Press F10.

ASCIIOUT Set Up

Check Values:

Variables to be Included:

All Variables = Yes

Output Parameters:

Output ASCII Header = Yes

Output ASCII Data = Yes

Output Scans marked Bad = No

Label Data Columns = Don’t Label Columns

Number of Lines Per Page = 50

Column Separator = Spaces

Add First Column = No

First Column Name = BLANK

First Column Value = BLANK

Julian Days Conversion Format = julian days

Press F10

ROSSUM Set Up

Check Values:

Variables to be Output Automatically:

Variable #0 = bottle position

Variable #1 = date time

Variables to be Derived:

Variable #0=density, sigma-theta [kg/m3]

Variable #1=density, sigma-t [kg/m3]

Variable #2=potential temperature IPTS-68 [deg C]

Variable #3= potential temperature IPTS-90 [deg C]

Variable #4=salinty, PSS-78 [PSU]

Variables #5-#19 = none

Additional Variable to be Averaged:

All variables = Yes, except Include Descent Rate [m/s] and Includes Number of Bottles Fired

Output Min/Max values for variables to be Averaged = No

Press F10

Once all files have been converted, FTP the files to /home/data65/pnb/CTD/`cruise’

Place *.DAT files in bin folder.

Place *.CNV files in cnv folder.

Place *.BTL files in btl folder.

Place *.ASC files in asc folder.

Place *.BL and *.ROS files in bl folder.

Once files have been transferred to UNIX via FTP, delete files from the PC. Be sure that the current calibration file does not get deleted.