The impact of the processes in the Southern Ocean on ENSO development

The paper presents the review of the model study of the role of the Southern Ocean in the processes of interaction of the ocean-atmosphere system at short time scales impacting the El Niño–Southern Oscillation (ENSO). It is shown that the variability of wind and atmospheric pressure over the Antarctic Circumpolar Current (ACC), together with the effects of the topography and coastline, significantly impact the development of ENSO events. A new paradigm for ENSO is proposed that allows explaining the current weakening of the interrelation between the variability in wind and water volume in the tropical warm pool in the western equatorial Pacific and the onset of ENSO. The weakness of the interrelationship between ENSO and variability in the equatorial warm water volume of the equatorial Pacific, together with wind variability in the western equatorial Pacific, can be explained by the fact that the process occurred in the Southern Ocean recently became a major contributor amplifying ENSO events. The reproduction in numerical models of ocean dynamics for the mechanism found can improve the accuracy of the forecast of El Niño events

Mechanisms for AMOC variability simulated by the NEMO model

We have investigated mechanisms for the Atlantic Meridional Overturning Circulation (AMOC) variability at 26.5° N (other than the Ekman component) that can be related to external forcings, in particular wind variability. Resolution dependence is studied using identical experiments with 1° and 1/4° NEMO model runs over 1960–2010. The analysis shows that much of the variability in the AMOC at 26° N can be related to the wind strength over the North Atlantic, through mechanisms lagged on different timescales. 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 timescales ~ 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 1/4° 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 26° N can be related to density changes in the top 1000 m in the Labrador and Irminger seas occurring ~ 4 years earlier

On maximal overdetermined Hardy's inequality of second order on a finite interval

summary:A characterization of the weighted Hardy inequality \left\| Fu \right\| _2 \le C \left\| F"v \right\| _2,\^^MF(0)=F'(0)=F(1)=F'(1)=0 is given