In the winter of 1991-1992 a convection experiment was conducted in th
e western Mediterranean Gulf of Lions, combining a variety of observat
ional techniques. An essential component was an acoustic tomography ar
ray, consisting of six moorings, designed to observe the time evolutio
n of the large-scale processes believed to be relevant in a convection
regime. Here two-dimensional slice inversions in three directions fro
m the central mooring are used to estimate the volume of convected wat
er and the mean convection depth and to observe the preconditioning an
d restratification processes before and after the convection. The near
-surface layer is well sampled by the acoustics, which show cooling an
d subsequent entrainment of the warmer Levantine Intermediate Water (L
IW) from below, in agreement with mixed-layer calculations. During the
2 months prior to the main convection event the total heat loss of th
e large-scale field is in approximate agreement with the surface heat
fluxes, showing that little net warm-water advection takes place from
outside the convection region. The implied confinement of water by the
local circulation should be an important factor in setting the locati
on and extent of the deep convection patch. The volume of water modifi
ed by convection in this winter is estimated to correspond to an area
of order 60 km radius and 1500 m depth. It is argued that the homogeni
zed area implies an annual mean deep water replenishment of 0.3 Sv. Th
e restratification, by the return of less dense water in the surface a
nd LIW layers, occurs first by rapid capping in the near-surface regio
n. Thereafter, the southern and eastern parts of the region restratify
in the deeper layers on a 40-day timescale, while a dense core of 50-
60 km diameter remains in the northwest until the end of the experimen
t.