Variable Names

Last updated Fri Nov 19 15:23:52 1999

Convention for specifying CODAS variables

1. DESCRIPTION

This manual page describes the syntax for specifying CODAS database variable names within control files. These are required by some utilities that access data regardless of the database content.

Variables must be specified by the name they have in the database. They must also be present in it. The name is case sensitive. The list of available names for a database can be displayed with showdb. Additional variable names which are not listed in the database are:

TIME: To access the profile time.
POSITION: To access profile position. The returned value will be a two element array with both longitude and latitude values.
LONGITUDE: To access profile longitude, only.
LATITUDE: To access profile latitude, only.

Note that the names that can be used depend firstly on the producer definition file used to create the CODAS database.

It is not possible to access a whole structure, however each of its element can be specified. The syntax is similar to the C programming language:

STRUCTURE_NAME.element_name

Access is limited to one structure level, i.e. if a structure element is a structure itself, you cannot access its values.

2. EXAMPLE

The following examples assume that the CODAS database to access has been created together with a producer definition file containing the following lines:

  ...

  PROFILE_VAR    8  SHORT     U                    0       1.E-3   m/s
  PROFILE_VAR    9  SHORT     V                    0       1.E-3   m/s
  PROFILE_VAR   54  SHORT     W                    0       1.E-3   m/s
  PROFILE_VAR   68  STRUCT    NAVIGATION           0       1       none
  PROFILE_VAR   69  STRUCT    BOTTOM_TRACK         0       1       none
  ...

  DEFINE_STRUCT  BOTTOM_TRACK  3
    ELEM         1  FLOAT     u                                    m/s
    ELEM         1  FLOAT     v                                    m/s
    ELEM         1  FLOAT     depth                                m

  ...

  DEFINE_STRUCT  NAVIGATION 4
    ELEM         1  DOUBLE   latitude                             deg
    ELEM         1  DOUBLE   longitude                            deg
    ELEM         1  DOUBLE   speed                                knots
    ELEM         1  DOUBLE   course                               deg

  ..

To access the velocities of an ADCP database, use U, V and W.

To access the percent good and spectral width of an ADCP database, use PERCENT_GOOD and SPECTRAL_WIDTH.

To access the ship's speed from the navigation, use NAVIGATION.speed.

To access the bottom tracking velocities, use BOTTOM_TRACK.u and BOTTOM_TRACK.v.

3. AUTHOR

Manual page written by Pierre Jaccard, Geophysical Institute, University of Bergen, 1999.

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