24 research outputs found
Characterizing, modelling and understanding the climate variability of the deep water formation in the North-Western Mediterranean Sea
Observing, modelling and understanding the climate-scale variability of the deep water formation (DWF) in the North-Western Mediterranean Sea remains today very challenging. In this study, we first characterize the interannual variability of this phenomenon by a thorough reanalysis of observations in order to establish reference time series. These quantitative indicators include 31 observed years for the yearly maximum mixed layer depth over the period 1980â2013 and a detailed multi-indicator description of the period 2007â2013. Then a 1980â2013 hindcast simulation is performed with a fully-coupled regional climate system model including the high-resolution representation of the regional atmosphere, ocean, land-surface and rivers. The simulation reproduces quantitatively well the mean behaviour and the large interannual variability of the DWF phenomenon. The model shows convection deeper than 1000 m in 2/3 of the modelled winters, a mean DWF rate equal to 0.35 Sv with maximum values of 1.7 (resp. 1.6) Sv in 2013 (resp. 2005). Using the model results, the winter-integrated buoyancy loss over the Gulf of Lions is identified as the primary driving factor of the DWF interannual variability and explains, alone, around 50 % of its variance. It is itself explained by the occurrence of few stormy days during winter. At daily scale, the Atlantic ridge weather regime is identified as favourable to strong buoyancy losses and therefore DWF, whereas the positive phase of the North Atlantic oscillation is unfavourable. The driving role of the vertical stratification in autumn, a measure of the water column inhibition to mixing, has also been analyzed. Combining both driving factors allows to explain more than 70 % of the interannual variance of the phenomenon and in particular the occurrence of the five strongest convective years of the model (1981, 1999, 2005, 2009, 2013). The model simulates qualitatively well the trends in the deep waters (warming, saltening, increase in the dense water volume, increase in the bottom water density) despite an underestimation of the salinity and density trends. These deep trends come from a heat and salt accumulation during the 1980s and the 1990s in the surface and intermediate layers of the Gulf of Lions before being transferred stepwise towards the deep layers when very convective years occur in 1999 and later. The salinity increase in the near Atlantic Ocean surface layers seems to be the external forcing that finally leads to these deep trends. In the future, our results may allow to better understand the behaviour of the DWF phenomenon in Mediterranean Sea simulations in hindcast, forecast, reanalysis or future climate change scenario modes. The robustness of the obtained results must be however confirmed in multi-model studies
The Social Conditions of Cultural Domination: Field, Sub-field and Local Spaces of Wind Music in France
Synthesis and Structural Study of [5.5](2,6)Pyridinophanes and -cyclophanes Containing Silylene Units
Short-term interactions between phytoplankton and intertidal seagrass vegetation in a coastal lagoon (Bassin dâArcachon, SW France)
The two "ages" of modernisation of allotments ::changing moral and aesthetic models
This chapter sheds light on the principle transformations to allotments taking place in Western Switzerland since the middle of the twentieth century. Based on a methodology combining an analysis of both written and spoken sources, it focuses on two periods (1950â1960 and 2000â2010) characterised by notable regulatory changes, demonstrating the extent to which the action taken by âreformersâ of these green spaces is grounded in different moral and aesthetic models, the nature of which mutates over time. Firstly, faced with the spectre of the rural wasteland in an urban setting, this chapter documents the transition, in the mid-twentieth century, of the traditional allotment into a clean, tidy familial pleasure garden. Secondly, we see how, throughout the 2000s, these reforms are undertaken with a view to rethinking the spectacle of the formal garden (in favour of a much more fluid style), and its use (âless privatisedâ) in a context where new forms of urban gardening (community gardens), âtaking up less spaceâ and âmore integrated into the urban fabricâ, continue to thrive. Finally, the chapter seeks to understand how the social history of these two âagesâ of modernisation of allotments can be interpreted as a long process of dual construction based, on the one hand, on a succession of off-putting images produced by the ideological and moral configuration dominant from one historic context to another and, on the other hand, on a process of social regulation and normalisation applied to communities perceived as marginal to or unaffected by mainstream concerns