CSIRO Division of Marine Research/RV Franklin CTD format guide

ctd_head.pdf

Station data format

Notes for FORTRAN users

Sample Station Data

SSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSS

S f90021001 60

SHIP : R.V. Franklin

STATION NUMBER : 1

DATE : 26-FEB-1990 (DAY NUMBER 57)

START TIME : 0636 UTC = Z

BOTTOM TIME : 0639 UTC = Z

FINISH TIME : 0652 UTC = Z

CRUISE : FR02/90

START POSITION : 43:12.58S 148:03.86E

BOTTOM POSITION : 43:12.54S 148:03.87E

FINISH POSITION : 43:12.56S 148:03.90E

MAXIMUM PRESSURE : 90 DECIBARS

BOTTOM DEPTH : 95 METRES

SSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSS

Station data format

For each station there are a total of 15 header records. These are followed by as many data records as are needed. Some header fields may be blank. Positions are determined from (in order of preference) 1. Gps, 2. back-calculated SATNAV data, 3. any other source. Note also that the maximum cast pressure is in decibars, and that the bottom depth is in metres, so for some deep stations the maximum cast pressure may be numerically greater than the bottom depth.

The header records are always in the same order, and all headers are always present, even if the information for some of the header records is not available.

The temperature scale for the temperature data is recorded in the 15th header record. This is always t68 (IPTS-68) for data up to the end of 1989, and t90 (ITS-90) from 01-JAN-1990 onwards. The conversion between the two temperature scales in the 'Oceanographic' range is :

    t68 = 1.00024 X t90 or

    t90 = 0.99976 X t68

Care should be used when using temperature to calculate any derived quantities such as theta or sigma-theta, as most existing equation of state routines expect temperatures in t68! For equation information have a look at the code in sal78.f

Where the 16 channel digitiser was used, the digitiser channel labels are in columns 81-92, 94-105, etc of header record number 14.

Each data record consists of the averages for 2 decibar bins centred on even integers. Missing data is indicated by blanks. The data records contain the fields :

and, if the 16 channel digitiser was in use,

Extended Data CTD Data Format description for FORTRAN users

The output format for our CTD data has changed in some ways. The basic format of the data files has remained unchanged, but now many files are concatenated into one. Normally, all stations for one cruise will be in one file, but, if data has been extracted for a specified area and range of dates, regardless of specific cruises, stations from many cruises will be in the same file.

The format of each file is such that it is easy to unpack the data into separate files for each station at the destination site.

There may or may not be some cruise header records. These header records will not be present when data from a number of cruises has been put into one file (such as when all stations within a time or lat/long range have been extracted from the archive). They can only be present when data has been extracted into one file per cruise, and may not be present then if they have not been requested.

Overall file structure

If the header records are present, the first record includes the count of the total number of header records. To skip the header records, either read this number and skip as appropriate, or read through the file until the first record consisting of 80 x 'S' characters is found.

The data for each station is preceded by a record consisting of 80 x 'S', then a record with an 'S', one blank space, the 9 character name that we used for the file on our system, then the total number of header and data records for the station.

Header format

If the header is present, the first record consists of the character 'H', the cruise id, the number of stations in the cruise, the cruise start and end dates, the number of 'quantity descriptor records', the number of comment records, the number of records in the station list and the total number of header records (including this record). They are written using the FORTRAN format (see example) :

      ('H ',a7,i5,2(x,a11),4i6)

A set of 'quantity descriptor records'. These records list all quantities present for this cruise and their units. (see example). Note that some quantities may not be present for all stations. These records all begin with a 'Q', and are preceded and followed by records consisting of 80 x 'Q' (these two records are included in the count in the first record).

A number of comment records. These records all begin with a 'C', and are preceded and followed by records consisting of 80 x 'C' (these two records are included in the count in the first record).

A station list. For each station number within the cruise, the station id, latitude, longitude, date (UTC), start time (UTC), bottom depth, maximum sample pressure and number of samples. If a station doesn't exist, the record is left blank. The information is written using the FORTRAN format

      ('L ',a9,2x,a9,2x,a10,2x,a11,2x,i4,'Z',4i6)

The station list is preceded and followed by records containing 80 x 'L' (these two records are included in the count in the first record).

A typical sequence of FORTRAN staements to skip over the header records (if present) would be:

    read(inunit,'(a80)')charbuf

    if(cbuf(1:1).eq.'S')then

        rewind(inunit)

    else

        read(charbuf(57:62),'(i6)')nhead

    do i=1,nhead-1

    read(inunit,'(a80)')charbuf

    end do

    end if

(the next record in either case will be the 'SSSSSSS....' record preceding the first station).

Station format

A typical sequence of FORTRAN statements to unpack a station would be:

    read(inunit,1000)file,nrecs

    1000 format(/,2x,a9,i8)

    if(nrecs.eq.-1)goto (finished)

    open(outunit,name=file//'.ave',form='formatted',status='unknown')

    do i=1,nrecs

        read(inunit,'(a)')charbuf

        write(outunit,'(a)')charbuf

    end do

close(outunit)

(finished) close(inunit)

The last station in a file is followed by a record of 'E's, then, in the next record, an 'E', a blank where the file name would have been, and -1 for the number of records.

Note that charbuf must be at least 79 characters long for cruises where the 16-channel digitiser was not in use, and at least (79 + ndig X 13) characters long for cruises where the 16-channel digitiser was in use. 'ndig' here is the number of digitiser channels in use. Any digitiser channels which were used can, of course, be ignored at this stage.

See example.

Station data format

For each station there are a total of 15 header records. These are followed by as many data records as are needed. Some header fields may be blank. Positions are determined from (in order of preference) 1. Gps, 2. back-calculated SATNAV data, 3. any other source. Note also that the maximum cast pressure is in decibars, and that the bottom depth is in metres, so for some deep stations the maximum cast pressure may be numerically greater than the bottom depth.

The header records are always in the same order, and all headers are always present, even if the information for some of the header records is not available.

The temperature scale for the temperature data is recorded in the 15th header record. This is always t68 (IPTS-68) for data up to the end of 1989, and t90 (ITS-90) from 01-JAN-1990 onwards. The conversion between the two temperature scales in the 'Oceanographic' range is :

    t68 = 1.00024 X t90 or

    t90 = 0.99976 X t68

Care should be used when using temperature to calculate any derived quantities such as theta or sigma-theta, as most existing equation of state routines expect temperatures in t68!

Where the 16 channel digitiser was used, the digitiser channel labels are in columns 81-92, 94-105, etc of header record number 14.

Each data record consists of the averages for 2 decibar bins centred on even integers. Missing data is indicated by blanks. The data records contain the fields :

and, if the 16 channel digitiser was in use,

A typical FORTRAN statement to read a data record is :

    read(inunit,1000)pres,temp,sal,sig,sva,geopan,dissox,nsam,tstd,cstd

    1000 format(f6.1,3f7.3,f7.2,f7.32x,f6.1,12x,i6,2f6.3)

or, if there are digitiser channels present,

    read(inunit,1000)pres,temp,sal,sig,sva,geopan,dissox,nsam,tstd,cstd,

$     (rdig(ii),ii=1,ndig)

    1000 format(f6.1,3f7.3,f7.2,f7.3,2x,f6.1,12x,i6,2f6.3,<ndig>(x,e12.5))

Example:

H fr02/90 143 26-FEB-1990 06-APR-1990 6 2 145 154

QQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQ

Q    Pressure     dB

Q    Temperature     T-90

Q    Salinity     psu

Q    Dissolved oxygen     mmol/dm**3

QQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQ

CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC

CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC

LLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLL

LLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLL

SSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSS

S f90021001 60

SHIP : R.V. Franklin

STATION NUMBER : 1

DATE : 26-FEB-1990 (DAY NUMBER 57)

START TIME : 0636 UTC = Z

BOTTOM TIME : 0639 UTC = Z

FINISH TIME : 0652 UTC = Z

CRUISE : FR02/90

START POSITION : 43:12.58S 148:03.86E

BOTTOM POSITION : 43:12.54S 148:03.87E

FINISH POSITION : 43:12.56S 148:03.90E

MAXIMUM PRESSURE : 90 DECIBARS

BOTTOM DEPTH : 95 METRES

SSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSS

S f90021002 70

SHIP : R.V. Franklin

STATION NUMBER : 2

DATE : 26-FEB-1990 (DAY NUMBER 57)

START TIME : 0730 UTC = Z

BOTTOM TIME : 0733 UTC = Z

FINISH TIME : 0745 UTC = Z

CRUISE : FR02/90

START POSITION : 43:12.87S 148:04.67E

BOTTOM POSITION : 43:12.87S 148:04.73E

FINISH POSITION : 43:12.95S 148:04.83E

MAXIMUM PRESSURE : 110 DECIBARS

BOTTOM DEPTH : 125 METRES

(remainder of station 2)

(intermediate stations)

(start of station 142)

SSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSS

S f90021143 70

SHIP : R.V. Franklin

STATION NUMBER : 143

DATE : 06-APR-1990 (DAY NUMBER 96)

START TIME : 2142 UTC = Z

BOTTOM TIME : 2144 UTC = Z

FINISH TIME : 2154 UTC = Z

CRUISE : FR02/90

START POSITION : 33:00.12S 151:57.71E

BOTTOM POSITION : 33:00.17S 151:57.70E

FINISH POSITION : 33:00.07S 151:57.84E

MAXIMUM PRESSURE : 110 DECIBARS

BOTTOM DEPTH : 117 METRES

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This page last updated: 17 November 1997