Le informazioni su questo evento sono disponibili solo in lingua inglese.
We have investigated mechanisms for the Atlantic Meridional Overturning Circulation (AMOC) variability at 26.5oN (other than the Ekman component) that can be related to external forcings, in particular wind variability. Resolution dependence is studied using identical experiments with 1o and ¼o NEMO model runs over 1960-2010.
The analysis shows that much of the variability in the AMOC at 26N can be related to the wind strength over the North Atlantic, through mechanisms lagged on different time scales. At ~1 year lag the January-June difference of mean sea level pressure between high and mid-latitudes in the North Atlantic explains 35-50% of the interannual AMOC variability (with negative correlation between wind strength and AMOC). At longer lead time scales ~4 years, strong (weak) winds over the northern North Atlantic (specifically linked to the NAO-index) are followed by higher (lower) AMOC transport, but this mechanism only works in the ¼° model. Analysis of the density correlations suggests an increase (decrease) in deep water formation in the North Atlantic subpolar gyre to be the cause. Therefore another 30% of the AMOC variability at 26N can be related to density changes in the top 1000 m in the Labrador and Irminger seas occurring ~4 years earlier.
Lecturer
Vladimir N. Stepanov
CMCC, Bologna
Bologna, Italy, Viale Aldo Moro, 42 - Viale Aldo Moro, 42, Bologna, Italy -
23 Oct 2014
Organized by
- CMCC - Centro Euro-Mediterraneo sui Cambiamenti Climatici