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ASCII Format Description

The ASCII (character) format used for the delivery of the data is moderately complex since it provides information in addition to the actual observations. The data format was originated by Canadian Marine Environment Data Service. It makes use of a number of international codes to describe the data and how they were collected. International vessel call sign tables and ship platform names are also provided.

ASCII Format Description

The data are organized in the following manner. A 'Station' record always appears first followed by one or more 'Profile' records. All records are of variable length, with the exact number of fields to be found being provided in the record.

The complete description of the fields of the format is provided below.

The 'Station' Record

The 'Station' record is built of a number of components. The first component always has a fixed number of fields and is always present. This component provides information about the location and time of the station, information about how the data were received and the number of repeats of other components found in the 'Station' record.

The second component provides information about the number of profiles measured at the station, whether or not a profile is a duplicate of another, higher resolution copy, and some information about the accuracy and precision of the variables measured. The deepest depth of each profile is recorded here. Because of limitations of records lengths on some computers, profiles are broken into a number of segments. Each segment has up to 1500 depth-variable pairs. There are as many repeats of this component as required to describe all profiles present. The actual number of profile records associated with a station is the sum of the number of segments of each profile.

The third component carries information about other variables measured at the station, such as winds, air temperature, and so on. The measurements are expressed as numeric values. A code table is used to indicate the variable measured. There are as many repeats of this component as required to describe all numeric variables present.

The fourth component carries information about other variables measured at the station but which are recorded as alphanumerics. Such measurements as Beaufort winds, QC tests executed, etc. are to be found here. There are as many repeats of this component as required to describe all alphanumeric variables present.

The last component records the processing history of the station. It provides information about who carried out which actions against what variable and when. If values have been changed, the original value is stored in this component. There are as many repeats of this component as required to describe all the processing that has taken place on the station.

Suppose that a temperature and a salinity profile were collected at a station. Suppose also that there were observations every meter to 3500 m depth. Suppose also that wind speed and direction were measured, that the Beaufort wind speed was recorded and that the station had 5 different actions taken against it. The layout of the station record is then as follows.

Component Contents
1 Station location, time and other information.
2 Two repeats of profile information, one for temperature and one for salinity.
3 Two repeats, one for each of wind speed and direction.
4 One repeat for the Beaufort code.
5 Five repeats of the history information, one to describe each action taken against the record.


The 'Profile' Record

There may be one or more 'Profile' records associated with each station record. The associated 'Profile' records always follow immediately after the station record to which they are linked.

There are two components to a 'Profile' record. The first always has a fixed number of fields and is always present. This component provides a repeat of the station location and time. It identifies the profile type and segment of that profile. It indicates if depths or pressures are recorded and how many depth-variable pairs are to be found.

The second component records the depth and measured variable as well as quality control flags that have been applied at each depth. There are as many repeats of this component as required to describe all depths (pressures) measured in the profile.

For the example data collection described above, the layout of the profile records is as follows.

Component Contents
1 Station location, time, profile and segment identifiers.
2 Up to 1500 repeats of depth-variable information and associated quality control flags.


File Organization

For the above example, the organization of a data file would be as follows.

Record Contents

Format Description

Field
Name
Field Size
Starting Position
Justify
(L / R)
Field Description
---------------------- -----------
--------------
---------
-----------------------------------------------------------------------
MKey char*08
01
L
Sort Key
One_Deg_sq char*08
09
R
MEDS geographic 1 degree square
Cruise_ID char*10
17
L
Radio callisgn + year for real time data, or NODC reference number for delayed mode data.
Obs_Year char*04
27
L
Century and year of Observation
Obs_Month char*02
31
L
Month of Observation
Obs_Day char*02
33
L
Day of Observation 01-31
Obs_Time char*04
35
L
Time of Observation
Data_Type char*02
39
L
Instrument type or type of IGOSS radio message
Iumsgno char*12
41
R
A unique identifier used by MEDS in their processing
Stream_Source char*01
53
L
A field used by MEDS to track if the data are new or have been retrieved from its archives.
Uflag char*01
54
L
Record update action
Stn_Number char*08
55
R
MEDS Station Number for real-time data, or cruise consec number for delayed mode data.
Latitude char*08
63
R
Decimal degrees (+ = north, - = south)
Logitude char*09
71
R
Decimal degrees (+ = west, - = east)
Q_Pos char*01
80
L
Station Position Quality
Q_Date_Time char*01
81
L
Date-Time Quality
Q_Record char*01
82
L
Worst Quality flag in the station
Up_Date char*08
83
L
Date of last action on record
Bul_Time char*12
91
L
Time bulletin was placed on GTS
Bul_Header char*06
103
L
GTS bulletin header
Source_ID char*04
109
L
GTS node which placed message on the GTS.
Stream_Ident char*04
113
L
Source and type of data
QC_Version char*04
117
L
Version of the QC program used.
Data_Avail char*01
121
L
Data Availability
No_Prof char*02
122
R
Number of Parameter profiles in station
Nparms char*02
124
R
Number of Surface Parameter groups
Nsurfc char*02
126
R
Number of Surface Codes groups
Num_Hists char*03
128
R
Number of History groups
 
Profile Information; repeats No_prof (1-30) times
 
No_Seg char*02
01
R
Number of Profile Records in the profile
Prof_Type char*04
03
L
Type of data in profile
Dup_flag char*01
07
L
'Y' indicates this station duplicates another higher quality.
Digit_Code char*01
08
L
Data Digitization method
Standard char*01
09
L
Standards to which the observations were made
Deep_Depth char*05
10
R
Depth (m) of the deepest observation in the profile.
 
Surface Parameter Group; repeats Nparms (0-30) times
 
Pcode char*04
01
L
Parameter - GF3 or User code.
Parm char*10
05
R
Measured surface parameter value.
Q_Parm char*01
15
L
Parameter Quality
 
Surface Codes Group; repeats Nsurfc (0-30) times
 
SRFC_Code char*04
01
L
Parameter - GF3 or User code.
SRFC_Parm char*10
05
L
Surface code
SRC_Q_Parm char*01
15
L
Parameter Quality
 
History Group; repeats Num_Hists (0-100) times
 
Ident_Code char*02
01
L
Organization which created the record
PRC_Code char*04
03
L
Computer program which modified the station and created a history group
Version char*04
07
L
Version of the above program
PRC_Date cahr*08
11
R
Date of action (YYYYMM)
Act_Code cahr*02
19
L
Action performed on parameter
Act_Parm char*04
21
L
Parameter code of changed parameter
Aux_ID char*08
25
R
Locator (e.g. depth) of changed parameter
Previous_Val char*10
33
R
Value of parameter before change
 
Profile Record
 
MKey char*08
01
L
Sort Key
One_Deg_sq char*08
09
R
MEDS geographic 1 degree square
Cruise_ID char*10
17
L
Radio callisgn + year for real time data or NODC reference number for delayed mode data.
Obs_Year char*04
27
L
Century and year of Observation
Obs_Month char*02
31
L
Month of Observation
Obs_Day char*02
33
L
Day of Observation 01-31
Obs_Time char*04
35
L
Time of Observation
Data_Type char*02
39
L
Instrument type or type of IGOSS radio message
Iumsgno char*12
41
R
MEDS field - not used
Profile_Type char*04
53
L
Type of data in the profile
Profile_Seg char*02
57
L
Profile segment number of this record
No_Depths cahr*04
59
R
Number of Depth/Pressure values in this record
D_P_Code char*01
63
L
Depth/Pressure code
 
Paramter Group; occurs No_Depth (1-1500) times
 
Depth_Press char*06
01
R
Depth or Pressure value
Depres_Q char*01
07
L
Depth/Pressure quality
Prof_Parm char*09
08
R
Measured parameter value
Prof_Q_Parm char*01
17
L
Data Quality