Accessing Argo data by float#

  

The Argo Online School 321 - Using Argo Data. Accesing Argo data by float.

Real-Time and Calibrated data

Since the target of the Argo program is to have the Argo data available within 12 hours of its transmission from the float, this data is called the Real-Time (RT) data. One year after the data were observed, it is adjusted if necessary, and made public. This calibrated data is called Delayed Mode (DM) data.

In section Real-Time and Delayed mode data we will describe in detail the differences between both kinds of data, and what are the quality control flags. However, to keep it simple, we will begin by focusing on the Real-Time (RT) data.

Data files organized by float

When accessing the dac folder, via the FTP or HTTP protocols, of any of the two GDACs you will find several (11) folders, one for each of the DACs. Within each one of these, folders there is one folder for each of the floats processed by this particular DAC.

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In the example here, we will use data from float with WMO number 6901254, which is processed by Coriolis (later we will see how to find the DAC for each float), therefore within the folder ./6901254, we find the following files and folder:

  • 6901254_Rtraj.nc

  • 6901254_meta.nc

  • 6901254_prof.nc

  • 6901254_tech.nc

  • profiles/

We will describe the content of each of these files later, but let’s focus on the folder profiles/ since it contains one file for each one of the hydrographic cycles carried out by the float. R6901254_001.nc is the file that contains the data from the first cycle. It begins with a R since it is the Real-Time data and if it begins with an D it would be adjusted data, or Delayed Mode data; we will see an example in section Real-Time and Delayed mode data¶.

Additionally, some Argo floats as 6901254, also made observations in the first descent from the surface to the parking depth. In this case, the name of the files with this data would be R6901254_001D.nc.

In general, the format of the file names for individual profiles are <R/D><FloatWmoID>_<XXX><D>.nc where :

  • The initial R indicates Real-Time data, the initial D indicates Delayed-Mode data

  • XXX is the cycle number

  • The second D indicates a descending profile, if exists, while profiles without this D are collected during ascent.

Note that it may happen that, in the future, you try to download the files from float 6901254 and there is no R6901254_001.nc and R6901254_001D.nc files, but you find only D6901254_001.nc and D6901254_001D.nc since the R-files are substituted by the D-files once the data is adjusted. We will describe that in detail in section Real-Time and Delayed mode data¶

The data from the float is pre-downloaded in the ./Data folder, but you can download it from the Coriolis GDAC. See the Data section for instructions on how to download the data.