HR: 1340h
AN: A23B-0793    [Abstracts]
TI: Study of the interannual Variability of the Thermohaline Circulation of the Mediterranean Sea With a Numerical Model
AU: * BOZEC, A
EM: alb@lodyc.jussieu.fr
AF: Laboratoire d'Oc\'eanographie DYnamique et de Climatologie (LODYC/IPSL), 4, Place Jussieu, PARIS, 75005 France
AU: Bouruet-Aubertot, P
EM: pba@lodyc.jussieu.fr
AF: LODYC/IPSL/UPMC, 4, Place Jussieu, PARIS, 75005 France
AU: Cr\'epon, M
EM: mc@lodyc.jussieu.fr
AF: LODYC/IPSL/CNRS, 4, Place Jussieu, PARIS, 75005 France
AU: Li, Z
EM: li@lmd.jussieu.fr
AF: Laboratoire de M\'et\'eorologie Dynamique (LMD/IPSL/CNRS), 4, Place Jussieu, PARIS, 75005 France
AB: The Mediterranean thermohaline circulation is mostly controlled by the density gradient between the Atlantic Ocean and the Mediterranean Sea, which is triggered by deep water formation. The purpose of this work is to investigate the mechanisms driving the variability of deep water formation, a major phenomenon that can modify the whole thermohaline circulation. We thus performed numerical simulations using a 1/8ø resolution model of the Mediterranean Sea, MED8. In a first stage, we characterize interannual variability under present climate conditions. Two simulations of 50 years are realized under different forcing conditions, either a climatogical or a random interannual forcing, that allow to isolate the intrinsic ocean variability from that induced by the atmospheric forcing. As expected a strong variability in the intermediate and deep water formation process was observed under random atmospheric forcing. Moreover some anomalous convective events arose in the Aegean basin after successive cold winters. There, intermediate water (250-1000m) became denser than the underlying deeper waters leading to new dense water formation. Nevertheless the impact of these intense events on the averaged thermohaline properties was weak. Indeed similar internal trend for the yearly averaged temperature and salinity, under both atmospheric conditions, was obtained showing the stability of the thermohaline circulation with respect to intense events. These results are eventually discussed in the light of the past 20 years in situ observations including the Big Transient event and its subsequent evolution.
DE: 3339 Ocean/atmosphere interactions (0312, 4504)
DE: 4215 Climate and interannual variability (3309)
SC: Atmospheric Sciences [A]
MN: 2004 AGU Fall Meeting