Important
notice to Argo users (pressure offset errors, 2nd notice):
This is to provide an update to the earlier notice (see http://www-argo.ucsd.edu/Acpres_offset.html, with regard
to progress in correcting pressure offset errors.
- Pressure offset errors in WHOI/FSI Argo float profiles include a
subset (a) that can be corrected exactly using automated procedures and a
subset (b) that requires expert examination to produce an approximate
correction.
- Profiles in subset (a) have now been corrected, and replacement of
GDAC files for these profiles will be completed by 20 October.
Procedures for real-time correction of these profiles are in place as of
10 October. These floats have been removed from the greylist as of 10
October, meaning the profiles will be available on the GTS.
- Profiles in subset (b) are undergoing expert examination and the
files are being replaced on the GDAC as they are completed. Errors are
noted in the files corresponding to the uncertainty in the pressure
correction. Since these profiles cannot be corrected automatically, the
corresponding instruments continue to be greylisted (i.e. profiles are
not on the GTS).
- While studying the pressure offset errors, a related problem was
discovered in a group of WHOI/SBE profiles. Reported pressures from these
instruments corresponded to the bottom pressure of bins rather than to the
mid-bin pressure. This ½ bin pressure offset error is generally less than
for the profiles noted in (1) above. For the affected WHOI/SBE
instruments, all profiles have now been corrected and are available on the
GDACS. The real-time data stream for these instruments has been corrected
(as of 14 September). These instruments are not greylisted.
WMO
ID numbers for the affected instruments in each of the groups discussed
above are posted below.
The Argo project will continue to improve procedures for detection and
correction of data quality problems, and Argo endeavors to provide data of
highest possible quality. Users should note that near real-time data are
subject only to automated quality checking, and the best quality data for
climate research applications are available only in delayed-mode (“D”
files). Users can assist by reporting any data quality problems to http://www-argo.ucsd.edu/supoort@argo.net
and to the AST co-chairs if the problems persist.
Dean Roemmich and Howard Freeland, on behalf of the international Argo
Steering Team