Argo is a global array of 3 800 free-drifting profiling floats that measures primarily the temperature and salinity of the upper 200m of the ocean.
In recent years, Argo floats have started to perform increasingly complex missions and a new data format was rolled out in order to accommodate multiple profiles from a single cycle.
Examples of additional profiles in a single cycle are available below:
- Bouncing profiles, which are a series of shallow profiles that do not reach the surface
- Near-surface observations that are sampled in a different way than the primary profile
- Biogeochemical observations that are sampled at different vertical levels than the primary profile (physical parameters)
Many Argo floats now measure biogeochemical data in addition to CTD data. For these floats, data are separated into three profile files:
- A core profile file that stores all the CTD measurements
- A B-profile that stores all the biogeochemical measurements
- A merged file called M-profile, produced by the GDACs (Global Data Assembly Center) which contains the CTD parameters and the associated biogeochemical parameters.
This new data format with the integration of multiple profiles from a single cycle, and the separation of measurements collected by a single Argo float into separate profile files, had a major impact on the data availability on the AODN Portal.
For example, the CSV output file contained duplicates of the CTD measurements from the various profile files for many of the Argo floats.
A few weeks ago, the dataset collection presenting the Argo data on the AODN Portal was updated in order to simplify the data access.
The dataset collection enables the user to visualise, filter and download all the core profiles collected since the beginning of the Argo program in an extended region around Australia.
This region covers the Indian Ocean and the Western Pacific Ocean up until the Equator, and the entire Southern Ocean (See screenshot of the AODN Portal).
The core profiles only provide the CTD measurements (Pressure, temperature and salinity) in CSV and netCDF data format.
Biogeochemical parameters, and in particular dissolved oxygen, are not currently available anymore from the AODN Portal.
Future developments of the AODN Portal will be required in order to visualise and download all the different new data streams collected by Argo floats.