Using Argo Data

Argo data is distributed by Global Data Access Centres (GDACs) in netCDF files - usually one file per profile. Their format is described in the Argo Users Manual found at International Data Management site. See also the Argo data beginners guide.

It is essential that attention is paid to the quality of the data, both using in-file quality indicators and the processing mode of the files themselves.

Processing mode

Argo filenames start with R or D, for Realtime or Delayed-mode. R files are generated within 24 hours of message transmission and the data has only automated corrections and quality flagging. D files result from reprocessing the data no less than 6 months after collection, using more rigourous tests and calibrations and involving data inspection by analysts under the direction of a Principal Investigator. So, D files cannot be used for near-realtime work, and R files should not be used for studies involving quality-assured data.

Profile data

Raw data and data after adjustments are stored for each property. For example, PRES contains pressure readings as sent by the float, and PRES_ADJUSTED data has had any known corrections applied. Unless you have a very specific reason do not use the raw data, even if no values are present in the _ADJUSTED variable.

Quality indicators

Each property profile variable also has a quality flag variable for the profile as a whole, eg PROFILE_PRES_QC, and a variable with flags for each individual measurement, eg PRES_QC. (See QC flag values). It is essential that these variables are consulted or you could use data known to be bad.

However, if the QC flag is '4' or greater ("known bad data"), then the corresponding _ADJUSTED value should have already been blanked.

Each adjusted property profile also has an uncertainty variable, eg PRES_ADJUSTED_ERROR. This is often, but not always, a default value for TEMP and PSAL, but for PRES commonly contains values (eg 20 dbar) which imply that the data should NOT be used for some purposes.