In 2014, Argo data management team decided to split core-Argo profiles and non-core-Argo profiles into two distinct profile files (C-File and B-File).

Both files have the same N_PROF dimension and, for each N_PROF, pressure values of the C-file are duplicated into the B-File.

A core-Argo profile file (C-File) contains the Core parameters provided by a float: pressure, temperature, salinity and conductivity.

The additional parameters are managed in a BGC-Argo data file (B-File). Two types of additional parameters are concerned: ‘intermediate’ parameters (provided by the float sensors) and BGC parameters (directly sampled by the float sensors or computed, at the DAC level, from Core and ‘intermediate’ parameters).

For a given float cycle and direction, the merged profile combines into one merged file (M-File) the Core and the BGC parameters. The M-File is generated by the GDAC, from the C-File and B-File provided by the DACs.

M-profile version 1

In version 1, the M-Profile is created from a concatenation of Core and BGC parameters (i.e. ‘intermediate’ parameters are ignored) along the common PRES axis of each N_PROF. Thus M-profile file has the same number of N_PROF arrays as the original C-File and B-File.

M-profile version 2

In version 2, the M-Profile is the merging of all N_PROF arrays of M-Profile version 1 into a single one.

Thus, in such M-Profile file:

• N_PROF = 1
• N_PARAM is equal to the number of Core and BGC parameters

The standard Argo profile structure is still used in M-Profile file: measurements are stored in a(N_PROF, N_LEVELS) array. However, as N_PROF = 1, we can consider that measurements are reported in a simple “matrix” of N_PARAM * N_LEVELS dimension: one column for each Core and BGC parameter, one level for each valid distinct pressure. The PRES vertical synthetic axis contains the sorted set of all valid distinct pressures. A valid pressure has a QC flag of ‘1’, ‘2’, ‘5’ or ‘8’ (‘good’, ‘probably good’, ‘changed’ or ‘estimated’ value). The number of valid distinct pressures is equal to N_LEVELS.

Each parameter value having a non-valid pressure is ignored.

A pressure value may have more than one value for a parameter (for example, BGC sensors may report specific Core parameter values that has been used to compute reported BGC parameter values). If the parameter is a Core-parameter, the value of the Core profile is selected. Otherwise, the first value of an ordered set (see “N_PROF priority” below) of the original N_PROF arrays is selected.

This document details the processing steps used to generate version 2 of merged profile data from Argo profile data. It also describes the format of the NetCDF files produced by the Coriolis GDAC to store these merged profile data.