@article{fdi:010073663,
  title = {{C}haracterizing, modelling and understanding the climate variability of the deep water formation in the {N}orth-{W}estern {M}editerranean {S}ea},
  author = {{S}omot, {S}. and {H}oupert, {L}. and {S}evault, {F}. and {T}estor, {P}. and {B}osse, {A}. and {T}aupier-{L}etage, {I}. and {B}ouin, {M}. {N}. and {W}aldman, {R}. and {C}assou, {C}. and {S}anchez-{G}omez, {E}. and de {M}adron, {X}. {D}. and {A}dloff, {F}. and {N}abat, {P}. and {H}errmann, {M}arine},
  editor = {},
  language = {{ENG}},
  abstract = {{O}bserving, modelling and understanding the climate-scale variability of the deep water formation ({DWF}) in the {N}orth-{W}estern {M}editerranean {S}ea remains today very challenging. {I}n this study, we first characterize the interannual variability of this phenomenon by a thorough reanalysis of observations in order to establish reference time series. {T}hese quantitative indicators include 31 observed years for the yearly maximum mixed layer depth over the period 1980-2013 and a detailed multi-indicator description of the period 2007-2013. {T}hen a 1980-2013 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. {T}he simulation reproduces quantitatively well the mean behaviour and the large interannual variability of the {DWF} phenomenon. {T}he model shows convection deeper than 1000 m in 2/3 of the modelled winters, a mean {DWF} rate equal to 0.35 {S}v with maximum values of 1.7 (resp. 1.6) {S}v in 2013 (resp. 2005). {U}sing the model results, the winter-integrated buoyancy loss over the {G}ulf of {L}ions is identified as the primary driving factor of the {DWF} interannual variability and explains, alone, around 50 % of its variance. {I}t is itself explained by the occurrence of few stormy days during winter. {A}t daily scale, the {A}tlantic ridge weather regime is identified as favourable to strong buoyancy losses and therefore {DWF}, whereas the positive phase of the {N}orth {A}tlantic oscillation is unfavourable. {T}he driving role of the vertical stratification in autumn, a measure of the water column inhibition to mixing, has also been analyzed. {C}ombining 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). {T}he 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. {T}hese deep trends come from a heat and salt accumulation during the 1980s and the 1990s in the surface and intermediate layers of the {G}ulf of {L}ions before being transferred stepwise towards the deep layers when very convective years occur in 1999 and later. {T}he salinity increase in the near {A}tlantic {O}cean surface layers seems to be the external forcing that finally leads to these deep trends. {I}n the future, our results may allow to better understand the behaviour of the {DWF} phenomenon in {M}editerranean {S}ea simulations in hindcast, forecast, reanalysis or future climate change scenario modes. {T}he robustness of the obtained results must be however confirmed in multi-model studies.},
  keywords = {{D}eep water formation ; {O}pen-sea deep convection ; {I}nterannual variability ; {M}editerranean {S}ea ; {R}egional climate models ; {C}limate trends ; {MEDITERRANEE} {NORD} {OUEST}},
  booktitle = {},
  journal = {{C}limate {D}ynamics},
  volume = {51},
  numero = {3},
  pages = {1179--1210},
  ISSN = {0930-7575},
  year = {2018},
  DOI = {10.1007/s00382-016-3295-0},
  URL = {https://www.documentation.ird.fr/hor/fdi:010073663},
}