A significant amount of hydrographic data has been collected in the Mediter
ranean during this century, providing the basic ingredients needed to const
ruct a climatological picture of the general circulation. A pooled hydrogra
phic data set has been prepared, which currently contains over 100,000 stat
ion profiles (CTD, Nansen bottle, XBT and MET) taken in the Eastern and Wes
tern Mediterranean Sea between 1900 and 1993. Climatological analyses of te
mperature and salinity data are performed at seasonal and monthly scales, u
sing a variational method and a finite element numerical technique. The var
iational formulation had been demonstrated to be equivalent to objective an
alysis, and a hybridation of the statistical and variational methods allows
to compute error fields associated to the climatology. The free parameters
of the scheme are determined using a cross-validation algorithm to extract
the best seasonal statistics from the observed data sets. Compared to earl
ier climatologies, the recent analyses show significant improvements with r
espect to the regional scales of the general circulation gyres. In addition
, several features of the general circulation are described with a better a
ccuracy. Finally, the barotropic equations (external mode) of a free-surfac
e, primitive equation model are integrated in time to diagnostically adjust
the sea-surface elevation to the thermohaline structures. Geostrophic velo
cities are then computed, integrating the thermal-wind equations with the s
ea-surface pressure as a reference. Results of fully prognostic, three-dime
nsional, primitive equation models are compared with these diagnostic compu
tations in order to identify which features of the general circulation can
be captured by observations. (C) 1998 Elsevier Science B.V. All rights rese
rved.