The response of the Mediterranean mean sea level to atmospheric pressu
re forcing is analyzed using 3 years of TOPEX/POSEIDON data. Coherence
analysis between mean sea level and atmospheric pressure shows a sign
ificant departure from a standard inverse barometer effect at frequenc
ies higher than 30 days(-1). At high frequencies the phase difference
between sea level and pressure is about 100 degrees, while it should b
e 180 degrees for a perfect inverse barometer response. This result is
in agreement with previous findings and confirms the role of the Stra
its of Gibraltar and Sicily in limiting the water exchange (and thus t
he response to atmospheric pressure forcing) at high frequencies. The
response of the Mediterranean mean sea level is then investigated usin
g the Candela [1991] analytical model which takes account of friction
in the Straits of Gibraltar and Sicily. The model explains a large par
t of the variance in TOPEX/POSEIDON mean sea level variations (50% for
the western basin and 38% for the eastern basin). Compared to an inve
rse barometer correction, it gives a smoother response with a phase de
lay at high frequencies. It also explains more variance in TOPEX/POSEI
DON mean sea level variations (5 cm(2) and 7 cm(2) for the western and
eastern basins, respectively). This demonstrates that this simple mod
el provides an improved correction of atmospheric pressure effects in
TOPEX/POSEIDON data. As the two corrections have an rms difference of
2-3 cm with maximum differences of up to 10 cm, the impact on the mapp
ing of oceanic circulation is not negligible. This is exemplified thro
ugh the comparison of sea level anomaly derived from the two correctio
ns.