XX century windstorms typology

• Main Author: Martins Varino, Filipa Catarina
• Other Authors: Centre national de recherches météorologiques (CNRM), Institut national des sciences de l'Univers (INSU - CNRS)-Météo France-Centre National de la Recherche Scientifique (CNRS), Université Paul Sabatier - Toulouse III, Philippe Arbogast, Gwendal Rivière, Bruno Joly
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: HAL CCSD 2017
• Subjects: Storm track; Cyclone tracking; 20th century; ERA-20C; Arctic warming; Climate change; Hazards jet stream; Reassurance; Suivi de tempêtes; 20ème siècle; Réchauffement arctique; Changement climatique; Dégâts; Courant de jet; Réassurance; [SDU.STU.ME]Sciences of the Universe [physics]/Earth Sciences/Meteorology; Arctic; Pacific; Tempêtes; Arctique*
• Online Access: https://tel.archives-ouvertes.fr/tel-02316144; https://tel.archives-ouvertes.fr/tel-02316144/document; https://tel.archives-ouvertes.fr/tel-02316144/file/2017TOU30389a.pdf

Extratropical cyclones (ETCs) variability is not only a subject that raises interest among the scientific community, but also extremely important in terms of social-economical impacts. Nevertheless, the study of both the extratropical cyclones variability and windstorms impacts is still scarce, particularly at time-scales that cover the twentieth century. This thesis aims to study, both storms track variability and associated losses from the beginning of the 20th century until 2010. In order to do so, the work was separated in two main parts, one witch focus on ETCs climatology during the last century using reanalysis data and another focused on loss indexes calculations and risk assessment of windstorms. The first part of this PhD concerns the study of ETCs variability after applying a tracking algorithm on the long-term ECMWF reanalysis ERA-20C. The number of ETCs per year shows three distinct periods for the moderate and deep cyclones. Two periods, one at the beginning and another at end of the century (1900-1935 and 1980-2010) for which no significant e trends are observed and a middle-century period between 1935-1980 which presents a significant positive trend. This last trend, however, a deeper analysis on this period should be done due to time-inhomogeneity of long-term reanalysis datasets. For this reason, a set of physical parameters are analysed and a physical interpretation made for each one of the periods. During the middle period, a general cooling of the atmosphere is observed, particularly at high-latitudes, which increases the meridional gradients of temperature and consequently baroclinicity and baroclinic conversion. Besides that, this increase is also observed more specifically in the Pacific (Atlantic) in the first (second) half of this period and linked with a Pacific Decadal Oscillation (Atlantic Multidecadal Oscillation) change in signs. On the opposite, the first and third periods are related with warmer polar temperatures that are more intense in the third period but never reach the ...