Winter long dry spells in the Mediterranean basin and associated atmospheric conditions : contemporary and future variability (1957-2100)

• Main Author: Raymond, Florian
• Other Authors: Biogéosciences UMR 6282 (BGS), Université de Bourgogne (UB)-Centre National de la Recherche Scientifique (CNRS), Université Bourgogne Franche-Comté, Pierre Camberlin, Albin Ullmann
• Format: Doctoral or Postdoctoral Thesis
• Language: French
• Published: HAL CCSD 2017
• Subjects: Mediterranaen Basin; Climatic variability; Winter droughts; Atmospheric conditions; Socio-Economic and environmental impacts; Climate change scenarios; Bassin Méditerranéen; Variabilité climatique; Sécheresses hivernales; Conditions atmosphériques; Impacts socio-Économiques et environnementaux; Scénarios du changement climatique; [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology; [SHS.GEO]Humanities and Social Sciences/Geography; North Atlantic; North Atlantic oscillation
• Online Access: https://theses.hal.science/tel-01780797; https://theses.hal.science/tel-01780797/document; https://theses.hal.science/tel-01780797/file/78901_RAYMOND_2017_archivage.pdf

In the context of climate change, as reflected by a dryer Mediterraneanbasin, this thesis focused on the study of the contemporary and future variability(1957-2100) of the wintertime (September to April) very long dryspells events (called VLDSe) in the Mediterranean basin. An original methodologywas developed in this thesis in order to define VLDSe as singularclimatic events, characterized by location, duration and spatial extent criteria.76 VLDSe were detected in the Mediterranean basin on the contemporaryperiod (1957-2013). These events are divided into 4 main geographicalpatterns: North-East, West, Scattered Localized and South-East. North-East and West configurations are associated with anticyclonic conditionslocated approximately 1 000 km northwestern to the areas affected by theVLDSe, favoring a clear sky and no precipitations. The Scattered Localizedand South-East configurations are special: the first one is characterized asa residual class grouping VLDSe with small spatial extent and distributedthroughout the entire basin, and the second one is characterized by seasonalVLDSe which are the continuation of the dry summer observed in the eastof the Mediterranean basin.Euro-Atlantic weather regimes have some control on the VLDSe. Thepositive phase of the north-atlantic oscillation regime (NAO+) is the onlyone that is clearly favorable to the development of VLDSe on almost the entirebasin. The east-atlantic regime (EA) does not show any control on theVLDSe, and the atlantic ridge (AR) and the negative phase of the northatlanticoscillation (NAO-) regimes are generally detrimental to VLDSe. However,some VLDSe can sometimes be associated with AR, EA and NAOregimes.This requires these three weather regimes to be associated withslightly higher atmospheric pressure northwest of the areas impacted bythe VLDSe, compared to their respective climatology. Long duration of theAR, EA and NAO+ regimes, which are coupled with sustained atmosphericstability, are preferentially associated with VLDSe, in contrast to the ...