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Accueil du site → Doctorat → Portugal → Stochastic space-time models for the characterization of precipitation extreme values. A contribution to the study of the desertification phenomenon

Universidade Técnica de Lisboa (2009)

Stochastic space-time models for the characterization of precipitation extreme values. A contribution to the study of the desertification phenomenon

Costa, Ana Cristina M

Titre : Stochastic space-time models for the characterization of precipitation extreme values. A contribution to the study of the desertification phenomenon.

Auteur : Costa, Ana Cristina M

Université de soutenance : Universidade Técnica de Lisboa

Grade : Doctor of Engineering Science 2009

Résumé
This research provides a qualitative classification of 107 daily rainfall series and evaluates spatiotemporal patterns in extreme precipitation by calculating climate indices at stations with records within the 1940–1999 period in the south of Portugal, where large areas have high susceptibility to desertification. Two procedures are proposed for the homogenization of climate time series. The direct sequential simulation and cosimulation algorithms, and the developed stochastic space-time models in particular, proved to be valuable procedures to deepen the knowledge on the space-time dynamics of precipitation extremes and to provide uncertainty assessments of the produced scenarios. The spatial patterns of precipitation extremes have become more homogenous during the last decades of the twentieth century, which is consistent with their decreasing relationship with elevation. On the other hand, climate variability is becoming greater in the time dimension. The most intense and more frequent rainfall events occur at areas of the Algarve region. The proposed simple aridity intensity index (AII) reflects increases in the magnitude of dryness. The southeast region is the most threatened by droughts and extreme dryness. Moreover, there is a tendency towards drier climatic conditions in coastal areas of the south and in the centre of the study region.

Mots clés : desertification ; homogenization ; precipitation extremes ; space-time dynamics ; climatic trends ; uncertainty

Présentation (DISCCRS)

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Page publiée le 13 janvier 2015, mise à jour le 12 juin 2017