The Stranger file format

This archive contains records from moored instruments - principally current meters but also other types instrument, such as temperature recorders, Seacat CTDs, pressure recorders, etc. All of the data here have the Buoy Group's Stranger format. The name is a reference to our use of this format when supplying data to outside ("stranger") organizations; internally, our data are stored in a compact binary format. The Stranger format utilizes the ASCII code and can be read and maniplulated with any text editor. It is easily readable by both humans and computers. The Stranger format is self-documenting, in the sense that each file contains its own metadata and formatting information.

We considered making these data available in netCDF format, which is gaining in popularity. We are aware, however, that users who are unfamiliar with netCDF or who lack software to deal with it may find the netCDF format more a deterrant than an aid to effective use of the data. We also realize that netCDF has shortcomings as an archival tool, since in time it may evolve or disappear. The ASCII code, on the other hand, is both stable and universally understood. Hence our decision to employ an ASCII format in the archive.

The records are presented as files that contain one or more time series. Each file corresponds to one instrument. Consider, for example, an experiment in which 30 instruments produced data. The experiment will be represented here by 30 files, one for each instrument. If a particular instrument recorded, say, speed, direction, temperature, and pressure, the file from that instrument will contain 6 time series: speed, direction, eastward component, northward component, temperature, and pressure. Note that we have redundantly included the two current components as well as speed and direction.

We show below a portion of a Stranger format current meter record:


    22 header lines
 11831 data lines
(i4,3i3,f8.2,f7.1,2f8.2,f8.3,f8.1,i6)                                   
Experiment name:  BEST (ACM4)             
Mooring name:     BEST 4                  
Mooring position:  30.003 deg S,   5.996 deg E
Instrument depth:   210 meters
Seafloor depth:    5180 meters
Instrument type:   Aanderaa RCM8
CMDB accession number:   1000
Parameters:  
      hour 
      day  
      month
      year 
      speed (cm/sec)    
      dir (deg true)    
      u (cm/sec)        
      v (cm/sec)        
      temp (deg C)      
      pressure (db)     
      line count
1800 23  6 92   16.61  283.0  -16.19    3.74  14.352   232.0     1
1900 23  6 92   15.75  289.0  -14.89    5.13  14.477   231.2     2
2000 23  6 92   17.19  286.0  -16.52    4.74  14.139   231.2     3
2100 23  6 92   20.35  282.0  -19.91    4.23  14.050   230.5     4
2200 23  6 92   18.34  275.0  -18.27    1.60  14.103   230.5     5
2300 23  6 92   18.91  276.0  -18.81    1.98  13.935   230.5     6
   0 24  6 92   19.20  276.0  -19.10    2.01  14.094   230.5     7
 100 24  6 92   19.20  275.0  -19.13    1.67  13.855   230.5     8
 200 24  6 92   20.06  272.0  -20.05    0.70  13.563   230.5     9
 300 24  6 92   15.46  261.0  -15.27   -2.42  13.837   230.5    10
      .
      .
      .

The file begins with metadata. Following the metadata, each line represents one sampling cycle and contains hour, day, month, year, speed, direction, eastward component, northward component, temperature, pressure and a line count. Note that if you read this file with a computer program, the first line of the file tells the program where the data begins, the second line tells it how many lines of data there are, and the third line describes the format of the data. The list following "Parameters:" describes the time series. In the example above, the file has 11831 data lines, though only the first 10 lines are shown here.

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