[CF-metadata] Ocean CTD data following CF Conventions v1.6

From: andrew walsh <awalsh>
Date: Mon, 2 Apr 2012 16:51:37 +1000

Hi CF list,

We are working on coding up some 1000's netCDF files off CTD
instruments and want to make usre we are following the
latest netCDF conventions (v1.6) OK. As background the CTD records
a profile pressure, temperature and salinity.

Here is a summarised CDL version (not all attributes+variables+qc flags there,
just majors for now)
of what we propose:

dimensions:
TIME=1
PRESSURE=729
LATITUDE=1
LONGITUDE=1

variables:
 double TIME(TIME) ;
  TIME:standard_name = "time" ;
  TIME:units = "days since 1950-01-01 00:00:00Z" ;
  TIME:axis = "T" ;
  TIME:valid_min = 0. ;
  TIME:valid_max = 999999. ;

 double LATITUDE(LATITUDE) ;
  LATITUDE:standard_name = "latitude" ;
  LATITUDE:units = "degrees_north" ;
  LATITUDE:axis = "Y" ;
  LATITUDE:valid_min = -90. ;
  LATITUDE:valid_max = 90. ;

   double LONGITUDE(LONGITUDE) ;
  LONGITUDE:standard_name = "longitude" ;
  LONGITUDE:units = "degrees_east" ;
  LONGITUDE:axis = "X" ;
  LONGITUDE:valid_min = -180. ;
  LONGITUDE:valid_max = 180. ;

   double PRESSURE(PRESSURE) ;
  PRESSURE:standard_name = "sea_water_pressure" ;
  PRESSURE:units = "decibars" ;
  PRESSURE:axis = "Z" ;
  PRESSURE:valid_min = 0. ;
 PRESSURE:valid_max = 12000. ;
  PRESSURE:positive = "down" ;

 double TEMPERATURE(PRESSURE) ;
  TEMPERATURE:standard_name = "sea_water_temperature" ;
  TEMPERATURE:units = "degrees_C" ;
  TEMPERATURE:_FillValue = -99.99 ;
  TEMPERATURE:valid_min = -2. ;
  TEMPERATURE:valid_max = 40. ;
TEMPERATURE:coordinates="TIME LATITUDE LONGITUDE PRESSURE"

  double SALINITY(PRESSURE) ;
  SALINITY:standard_name = "sea_water_salinity" ;
  SALINITY:units = "psu" ;
  SALINITY:_FillValue = -99.99 ;
  SALINITY:valid_min = 0. ;
  SALINITY:valid_max = 40. ;
SALINITY:coordinates="TIME LATITUDE LONGITUDE PRESSURE"

// global attributes:
   :conventions = "CF-1.6" ;
  :featureType = "profile"
  :cdm_data_type = "profile"
+ several other attributes later for ISO19115 metadata generation

I am not sure if I should have TEMPERATURE and SALINITY arrays with 4
dimensions
like TEMPERATURE(TIME,LATITUDE,LONGITUDE,PRESSURE) or just 1 dimension
like I have above i.e. TEMPERATURE(PRESSURE). ?

Any feedback on the above is greatly appreciated.

Andrew Walsh
Received on Mon Apr 02 2012 - 00:51:37 BST