Explanation of new Version 3 profile file system

The new Version 3.0 and 3.1 single-cycle profile files are now available on the Argo GDACs to accommodate the increasing vertical complexity of the global Argo array. The main feature of the new Version 3 profile files is the ability to accommodate multiple profiles in a single-cycle. A V3 profile file contains all the profiles from a single cycle. The minimum number of profiles per cycle is one. There is no maximum number of profiles per cycle. This means that some single-cycle profile files will contain multiple profiles with different vertical sampling schemes indicated by N_PROF > 1. The new V3 variable VERTICAL_SAMPLING_SCHEME variable refers to Table 16 in the User's manual available in the Documents section of the ADMT website which details the various vertical sampling schemes that currently exist in the global Argo array. Please note that a new profile may be needed due to either a parameter being measured on different pressure levels from the CTD profile OR a parameter being measured using a different method - ie pumped vs. unpumped CTD measurements.

Here are some examples of additional profiles in a single-cycle:

  • 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 (with the CTD pump turned off, for example)
  • Biogeochemical observations that are sampled at different vertical levels than the primary profile

The main Argo CTD profile is stored in N_PROF=1. All other parameters (including biogeochemical parameters) that are measured with the same vertical sampling scheme and at the same location and time as the main Argo CTD profile are also stored in N_PROF=1.

Storing biogeochemical data: core-, B-, M-profile files

Many floats in the global Argo array now measure biogeochemical data in addition to CTD data. For these floats, data are separated into two profile files: a core profile file that stores all the CTD measurements, and a B-profile file that stores all the biogeochemical measurements, including both the raw measurements and the derived parameters. The two files are linked by the parameter PRES.

Note that these single-cycle core and B-profile files can have multiple vertical sampling schemes (N_PROF > 1), as described above. In these cases, the two files are linked by PRES and N_PROF.

Here is an example. Suppose a hypothetical float carries a CTD sensor, a nitrate sensor and an oxygen sensor. In each single-cycle, this hypothetical float is configured to return two profiles: (1) a 2-dbar interval CTD profile to 1000 dbar with corresponding oxygen measurements but with no corresponding nitrate measurements, and (2) a 45-dbar interval nitrate profile to 900 dbar with corresponding CTD measurements but with no corresponding oxygen measurements. The parameters in the resulting core and B-profile files are formatted as follows:

In the core profile file, N_PROF = 2, N_LEVELS = 500.

PRES = [2,4,6, ...........................................,1000];
= [45,90,135,...,900,FillValue,.................];
N_PROF = 1
N_PROF = 2
TEMP = [T2,T4,T6,...................................,T1000];
= [T45,T90,T135,...,T900,FillValue,........];
N_PROF = 1
N_PROF = 2
PSAL = [S2,S4,S6,.................................,S1000];
= [S45,S90,S135,...,S900,FillValue,......];
N_PROF = 1
N_PROF = 2

In the B-profile file, N_PROF = 2, N_LEVELS = 500.

PRES = [2,4,6, ...........................................,1000];
= [45,90,135,...,900,FillValue,.................];
N_PROF = 1
N_PROF = 2
DOXY = [DO2,DO4,DO6,.....................DO1000];
= [FillValue,................................................];
N_PROF = 1
N_PROF = 2
NITRATE = [FillValue,................................................];
= [N45,N90,N135,...,N900,FillValue,......];
N_PROF = 1
N_PROF = 2

(Other intermediate oxygen and nitrate variables in the B-file are omitted in this example.)

To facilitate users who want to access both the CTD and the biogeochemical data in one file, the GDACs will produce a merged file, called the M- profile file, which contains the CTD parameters and the derived ocean state biogeochemical parameters. The same N_PROF > 1 structure applies to the M- profile file.

Users should refer to Table 3 in the Argo User’s Manual for a complete list of all Argo biogeochemical parameters. Please note that some biogeochemical variables can be multi-dimensional. Users are urged to check the attributes of the biogeochemical variables carefully when reading them in the Argo netcdf files.