The Ajaccio site is equipped with one tide gauge, which
is the property of SHOM (Service Hydrographique et
Oce´anographique de la Marine), as part of the RONIM
network (Re´seau d’Observation du Niveau de la Mer).
The quality-controlled data are provided by the REFMAR
(Re´seau de Re´fe´rence des observations Mare´graphiques)
distribution centre, at a 10-min sample rate. Because there
is only one instrument at the Ajaccio site, there is no mean
to recover the data if the tide gauge breaks down. In particular,
all the measurements dated from the 28/05/2008
to the 15/09/2009 were eliminated by the SHOM because
of jumps and periods of constant values in the SSH. That
was due to a technical problem with the instrument and
the tide gauge has been replaced since then. A deeper analysis
by NOVELTIS and the OCA, using the Senetosa data
for cross-comparisons, showed that there were still many
outliers and a large drift in the data from the 29/03/2008.
Many other spurious measurements were also identified
and removed from the time series, thanks to this second
careful cross-checking analysis. It must also be noticed that
the Ajaccio instrument had a recording resolution of 1 cm
before it was changed in September 2009. Consequently,
for each altimeter cycle, the bias estimate obtained at this
site during the first period of the tide gauge recording cannot
reach a precision better than 1 cm.