Climate change impact on wave climate in coastal area, using dynamical downscaling : application to the Aquitanian coast, France.

• Main Author: Charles, Elodie
• Other Authors: Bureau de Recherches Géologiques et Minières (BRGM) (BRGM), Groupe d'étude de l'atmosphère météorologique (CNRM-GAME), Institut national des sciences de l'Univers (INSU - CNRS)-Météo France-Centre National de la Recherche Scientifique (CNRS), Bourse de doctorat du Fonds AXA pour la Recherche, Université Toulouse III - Paul Sabatier, Pascale Delecluse, CNRM/Météo-France, St-Mandé, Déborah Idier, BRGM, Orléans
• Format: Thesis
• Language: French
• Published: HAL CCSD 2012
• Subjects: waves; climate change; projection; modelling; dynamical downscaling; Aquitanian coast; Bay of Biscay; multi-decadal trends; interannual variability; teleconnection patterns; weather regimes; vague; changement climatique; modélisation; régionalisation dynamique; côte aquitaine; Golfe de Gascogne; tendances multi-décennales; variabilité interannuelle; modes de téléconnexion; régimes de temps; geo; envir; North Atlantic; North Atlantic oscillation
• Online Access: https://hal.archives-ouvertes.fr/tel-01280874/file/Charles_Memoire_These_2012.pdf; https://hal.archives-ouvertes.fr/tel-01280874

The Aquitanian coast, as well as most coastal regions, is influenced by several hydrodynamical factors. Those factors can be modified by climate change. This study aims at studying climate change impact mainly on wave conditions which affect the Aquitanian coast.Using dynamical downscaling, waves are modelled from the North Atlantic Ocean towards the Bay of Biscay at a 10 km spatial resolution exclusively from wind fields. Waves are simulated with WAVEWATCH III spectral wave model, for the present climate (wind fields issued from the ERA-40 reanalysis) and for a control scenario and three future greenhouse gas emission scenarios (A2, A1B, B1) (wind fields issued from the RETIC simulations of ARPEGE-Climat). The database calibration and validation are based on local buoy measurements. Wind fields issued from climate model present systematic biases, therefore, a quantile-quantile correction is applied to wave projections.Wave climate evolution analysis is done in two steps. Firstly, present wave climate (1958-2001) is investigated regarding multi-decadal trends and interannual variability. A significant increase of summer wave height is identified on the period 1970-2001 (0.54 cm/y at the Biscay buoy). Concerning largest wave heights, a significant shift of directions is noticed for autumn (up to −0.47°/y from 1974 to 2001 at the Biscay buoy) and spring (0.3°/y from 1958 to 2001 at the Biscay buoy). The strong interannual variability of wave conditions is correlated to several general atmospheric circulation preferential modes (teleconnexion patterns and weather regimes). This underlines a strong link between local wave conditions and climate. For instance, the winter wave height and direction anomalies within the Bay of Biscay are strongly correlated to the North Atlantic Oscillation and the East Atlantic teleconnection pattern indices. Secondly, wave condition changes between present climate (1961-2000) and future scenarios (2061-2100) are investigated and analysed. A general decrease of wave heights is noticed ...