Climatological variations of total alkalinity and total dissolved inorganic carbon in the Mediterranean Sea surface waters

Abstract. A compilation of data from several cruises between 1998 and 2013 was used to derive polynomial fits that estimate total alkalinity (AT) and total dissolved inorganic carbon (CT) from measurements of salinity and temperature in the Mediterranean Sea surface waters. The optimal equations were chosen based on the 10-fold cross-validation results and revealed that second- and third-order polynomials fit the AT and CT data respectively. The AT surface fit yielded a root mean square error (RMSE) of ± 10.6 μmol kg−1, and salinity and temperature contribute to 96 % of the variability. Furthermore, we present the first annual mean CT parameterization for the Mediterranean Sea surface waters with a RMSE of ± 14.3 μmol kg−1. Excluding the marginal seas of the Adriatic and the Aegean, these equations can be used to estimate AT and CT in case of the lack of measurements. The identified empirical equations were applied on the 0.25° climatologies of temperature and salinity, available from the World Ocean Atlas 2013. The 7-year averages (2005–2012) showed that AT and CT have similar patterns with an increasing eastward gradient. The variability is influenced by the inflow of cold Atlantic waters through the Strait of Gibraltar and by the oligotrophic and thermohaline gradient that characterize the Mediterranean Sea. The summer–winter seasonality was also mapped and showed different patterns for AT and CT. During the winter, the AT and CT concentrations were higher in the western than in the eastern basin. The opposite was observed in the summer where the eastern basin was marked by higher AT and CT concentrations than in winter. The strong evaporation that takes place in this season along with the ultra-oligotrophy of the eastern basin determines the increase of both AT and CT concentrations

Phenomenology and physical origin of shear-localization and shear-banding in complex fluids

We review and compare the phenomenological aspects and physical origin of shear-localization and shear-banding in various material types, namely emulsions, suspensions, colloids, granular materials and micellar systems. It appears that shear-banding, which must be distinguished from the simple effect of coexisting static-flowing regions in yield stress fluids, occurs in the form of a progressive evolution of the local viscosity towards two significantly different values in two adjoining regions of the fluids in which the stress takes slightly different values. This suggests that from a global point of view shear-banding in these systems has a common physical origin: two physical phenomena (for example, in colloids, destructuration due to flow and restructuration due to aging) are in competition and, depending on the flow conditions, one of them becomes dominant and makes the system evolve in a specific direction.Comment: The original publication is available at http://www.springerlink.co

An assessment of the role of the third stress invariant in the Gurson approach for ductile fracture

International audienc

Continuum damage mechanics and local approach to fracture: Numerical procedures

International audienc

Conditions de bifurcation à l’intérieur et aux frontière pour une classe de matériaux non-standards. (Bifurcation conditions inside and at the boundary for a class of non-standard materials)

International audienc

Phénomènes de localisation à la frontière d’un solide. (Localization phenomena at the boundary of solids)

International audienc

A Gradient-Enhanced Damage Approach to Fracture

A gradient-enhanced damage is formulated in which the Laplacian of the internal variable which memorises the damage enters the damage loading function in addition to the conventional dependence on this internal variable itself. The computational setting for this higher-order continuum model is fully elaborated. Its embedment in thermodynamics is discussed and some remarks are made on the additional boundary conditions that arise. Finally, the special case is discussed for which there is a linear relation between the damage variable and the internal variable that memorises the damage evolution