dmqc-4 agenda item 2.2 the apex truncated negative pressure drifts (tnpds) ● can independent...

DMQC-4 agenda item 2.2

The APEX Truncated Negative Pressure Drifts (TNPDs)

● Can independent analyses be done on a regular basis? How to distribute their results to delayed-mode operators?

● How to qc APEX TNPDs? T-S analysis cannot detect pressure errors < ~|20| dbar. All APEX groups need to qc TNPD floats in delayed-mode in a consistent way.

● How to inform users? Is the CSIRO webpage updated/sufficient? See http://www.marine.csiro.au /~cow074/quota/argo_offsets.htm.


The APEX correctables

Any problems with the agreed delayed-mode procedures?

(See Argo QC Manual Version 2.4, p.17-19.)


Delayed-mode progress from each APEX group on pressure correction

APEX group

(in alphabetical order)

Implemented DM PRES CORR for new D-files?

Re-processed old D-files with DM PRES CORR?

Expected date of completion

AOML/PMEL - US YES YES N/A

AOML/UW - US YES YES N/A

BODC - UK

CHINA

CORIOLIS - FRANCE, GERMANY, etc …

CSIRO - AUSTRALIA

INCOIS - INDIA

JAMSTEC - JAPAN

KOREA

MEDS - CANADA

DMQC-4 agenda item 2.4 (cont.)

Thoughts on pressure accuracy after adjustment

The current model of pressure correction:

PRES_ADJUSTED = PRES − SP

improves the pressure data, but does not account for all pressure errors.

Lab tests have shown that the pressure sensor drift rate has a slope and an offset. The offset also is temperature-dependent. However, these parameters cannot be determined unless the floats are retrieved for laboratory re-calibration. So the current adjustment method is still the best we can do.

After correcting for gross pressure drift, data are accurate to a few decibars … implications for ocean heat budget estimates.


Do SOLO, PROVOR, NEMO, NINJA floats need additional pressure qc to detect Druck microleaks?

Editting real-time qc flags in delayed-mode

Change definitions of PARAM and PARAM_QC in User’s Manual and QC Manual:-

▪ PARAM contains the raw values telemetered from the floats. PARAM = PRES, TEMP, CNDC, PSAL.

(DOXY should have its own definition.)

▪ PARAM_QC contains qc flags that pertain to the values in PARAM. Values in PARAM_QC are set initially in ‘R’ and ‘A’ modes by the automatic real-time tests. They are later modified in ‘D’ mode at levels where the qc flags are set incorrectly by the real-time procedures, and where erroneous data are not detected by the real-time procedures.

DMQC-4 agenda item 4

DMQC-4 agenda item 4 (cont.)

Raw flags

Raw flag comments After DMQC

1 Good data.

No adjustment needed.

1

2 Good data that may contain small sensor drift.

1 or 2 or 3

3 Bad data that may be usable after adjustment.

1 or 2 or 3

4 Bad data. Do not use. 4


DM flags Delayed-mode flag comments

1 Good data.

2 Probably good data.

3 An adjustment has been applied, but the value may still be bad.

4 Bad data. Not adjustable. Data replaced by ‘FillValue’.

Editting real-time qc flags in delayed-mode

(cont.)

The need to keep copies of original R files.


Miscellaneous issues

6.1. D files format errors. Can these be checked regularly, e.g. every 3 months with the Argo reference database update? Made output available on the same Coriolis ftp site?

6.2. A dedicated DMQC website?

(show Regional_Summary_table2.html)

6.3. Time delay in re-processing D files; e.g. after feedback from altimetry qc.

DMQC-4 agenda items 6.1, 6.2, 6.3

“Argo Data Management”

Pouliquen et al, Community White Paper to OceanObs09

The main actors in Argo data management are:

DACs, GDACs, ARCs, AIC, delayed-mode operators.


dmqc-4 agenda item 2.2 the apex truncated negative pressure drifts (tnpds) ● can independent...

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