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January 13, 1992
CTD data are distributed in a format specified by the international WOCE Hydrographic Programme Office (WHPO). This document describes that format.
Each station/cast is stored in a separate file. A file's name can be determined by the concatenation of 'h', 2 digit cruise number, 'a', a 2 digit station number, a 2 digit cast number and a file extension of ctd. For example, HOT-1, station 2, cast 3, would be found in h01a0203.ctd.
The cruise and position information for each cast is in the cruise summary file (*.sum). The EXPOCODE, station number and cast number can be used to cross-reference the CTD data files with the cruise summary file. This code allows for the identification of the cruise. It consists of a 4 character NODC country-ship code, a maximum of 8 character cruise number followed by a "/" and leg number. For example, the EXPOCODE for HOT-13 on the R/V Moana Wave would be 31MW013/1.
The CTD data file has a fixed record length of 65 characters / record. The first six records of a CTD file contain header information:
Record 1:
Column Format Item
9-22 a14 EXPOCODE (KA=Kaimalino,WE=Wecoma,MW=Moana Wave)
31-34 a4 WHP station identification
41-42 i2 Month
43-44 i2 Day
45-46 i2 Year
FORTRAN FORMAT (8x,a14,8x,a4,6x,3i2)
C "%*s %s %*s %s %*s %2d%2d%2d"
Record 2:
7-12 a6 Station number
20-22 i3 Cast number
36-40 i5 Number of data records in the file
FORTRAN FORMAT (6x,a6,7x,i3,13x,i5)
C "%*s %d %*s %d %*s %d"
Record 3:
16-21 i6 Instrument number
37-41 f5.2 Sampling rate (hz)
FORTRAN FORMAT (15x,i6,15x,f5.2)
C "%*s %d %*s %f"
Record 4:
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Headers for data columns (variable labels).
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Unit header for data columns.
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Quality byte designators. All columns requiring a quality
byte are underscored by seven asterisks.
Data Record Format:
Column Format Item
1-8 f8.1 Pressure (Decibars)
9-16 f8.4 Temperature (Degrees Celsius, ITS90)
17-25 f9.4 Salinity (1978 International Practical Salinity Scale)
26-33 f8.1 Oxygen (micromoles per kilogram)
34-41 f8.3 Transmission (% transmission)
42-49 f8.3 Fluorescense (wt/(cm**2))
50-57 i8 Number of observations averaged at this pressure level
58-65 i8 Quality (defined by investigator) **
FORTRAN FORMAT (f8.1, f8.4, f9.4, f8.1, 2f8.3, i8, i8)
C "%f %f %f %f %f %f %d %d"
** The quality word is the left-to-right concatenation of required quality bytes
for the variables measured. They are defined as follows:
byte value DefinitionSample File: (First and last few records)
1 Not calibrated with water samples. 2 Acceptable measurement. 3 Questionable measurement. 4 Bad measurement. 5 Not reported. 6 Interpolated value. 7 Not assigned for CTD data 8 Not assigned for CTD data 9 Not sampled
EXPOCODE 31MW013/1 WHP-ID PRS2 DATE 010790 1
STNNBR 1 CASTNO 2 NO. RECORDS= 512 2
INSTRUMENT NO. 91361 SAMPLING RATE 24.00 HZ 3
CTDPRS CTDTMP CTDSAL CTDOXY XMISS FLUOR NUMBER QUALT1
DBAR DEG C PSS-78 UMOL/KG %TRANS WT/CM2 OBS. *
******* ******* ******* ******* ******* ******* *
0.0 25.0409 34.9405 -99.0 -99.000 0.008 36 222992
2.0 25.0391 34.9409 -99.0 -99.000 0.008 204 222992
4.0 25.0381 34.9411 -99.0 -99.000 0.008 84 222992
6.0 25.0379 34.9412 -99.0 -99.000 0.008 36 222992
1004.0 3.8761 34.5064 -99.0 -99.000 0.009 60 222992
1006.0 3.8740 34.5063 -99.0 -99.000 0.009 60 222992
1008.0 3.8729 34.5065 -99.0 -99.000 0.009 48 222992
1010.0 3.8719 34.5064 -99.0 -99.000 0.009 96 222992
1012.0 3.8726 34.5064 -99.0 -99.000 0.010 60 222992
1014.0 3.8721 34.5064 -99.0 -99.000 0.009 60 222992
1016.0 3.8715 34.5065 -99.0 -99.000 0.009 84 222992
1018.0 3.8700 34.5066 -99.0 -99.000 0.009 60 222992
1020.0 3.8700 34.5066 -99.0 -99.000 0.009 180 222992
1022.0 3.8705 34.5066 -99.0 -99.000 0.009 477 222992
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