Combining the Argo QC data

Introduction

An intermediate step is to collect argo QC data from the files we have downloaded and put them all into one file for each Argo platform ID.

For the purpose of this project, the delayed mode argo data - data which is been thorougly quality control tested - is taken as the nearest thing we have to the truth. This is the data which is used to set the crucial dimensions, such as the number of profiles for the year and how many levels there are per profile. It is also assumed to give the definitive pressure, temperature and salinity.

Where we don't have delay mode data (when DATA_MODE is "R" or "A", for real-time or adjusted, instead of "D", for delayed mode), the argo data is still used to set the crucial dimensions for convenience - although arguably data from other sources may be just as good or better.

The combined data is written to files below /glusterfs/marine/users/resc/Argo_QC_work/insert_argo. The unlimited dimension in these files is nObs, which is the number of DACs (or Observation centres) in this file. The variable DAC(nObs) gives a code which indicates which DACs are contained in this file. DAC = 0 corresponds to the argo data. The combined files are created from /glusterfs/marine/users/resc/Argo_QC_work/code with the command

./insert_argo --argoid=⟨Argo Id⟩ --year=⟨year&rang --dac=d_mode

to create one file, or to create all the files for one year use:

./insert_argo --argoid=all --year=⟨year&rang --dac=d_mode

Having written the argo data, it is then possible to add data from one of the DACs, which will increase the nObs dimension by one, with the command

./insert_argo --argoid=⟨Argo Id⟩ --year=⟨year&rang --dac=⟨dac⟩

where ⟨dac⟩ will be something like bmrc or ukmo. Again use --argoid=all to add the data for all argo IDs, although if you want to write over existing data use --argoid=all-overwrite (otherwise, existing data will not be overwritten).

Depth

The depth in the argo data is given in pressure pascals, where as some of the DACS used depth in metres as the vertical scale. To convert the depth in pascals I've used the equation on http://www.seabird.com/application_notes/AN69.htm

Matching levels

Matching levels when the vertical levels are both given in pascals is more reliable than when the vertical levels are in different units, namely pascal and metres. However even then, the pressure level is still a measurement and so its value depends on quality control. Hence, levels often don't match precisely and sometimes it is difficult to match levels at all.

Matching of levels has been done with two tests

1. For each depth level in the argo data the nearest depth level in the DAC data has been found
2. We don't want multiple argo levels attached to the same DAC level. To ensure this doesn't happen, test that both the argo level above and below our selected argo level are further away from this DAC level than our selected argo level.