Interannual-to-decadal variability in North Altlantic and Nordic Seas. Study of observations, hindcasts and reanalyses.

• Main Author: Lecointre, Albanne
• Other Authors: Laboratoire des Écoulements Géophysiques et Industriels Grenoble (LEGI), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS), Université Joseph-Fourier - Grenoble I, Bernard Barnier([e-mail])
• Format: Doctoral or Postdoctoral Thesis
• Language: French
• Published: HAL CCSD 2009
• Subjects: Physical oceanography; Numerical modelling; Data assimilation; Spatial resolution; North Atlantic; Meridional Overturning Circulation; Meridional Heat Transport; Océanographie physique; Modélisation numérique; Assimilation de données; Résolution spatiale; Atlantique Nord; Circulation d'overturning méridienne; Transport méridien de chaleur; [SDU.OCEAN]Sciences of the Universe [physics]/Ocean; Atmosphere; Nordic Seas
• Online Access: https://theses.hal.science/tel-00470520; https://theses.hal.science/tel-00470520/document; https://theses.hal.science/tel-00470520/file/these.pdf

This work aims to characterise and quantify the differences between large-scale oceanic climatic indices simulated by a 9-member set of realistic numerical ocean models (five hindcasts and four reanalyses). The focus is on the North Atlantic region. The following climatic indices : meridional overturning circulation and meridional heat transport, are diagnosed in the various models. The models are run over a common period of nine years. The focus of this study is climatic variability at interannual scales. The influence of numerical parameters, such as spatial configuration and resolution, and the influence of various sequential data assimilation schemes, are evaluated. We evaluate them through comparison with observed large-scale climatic indices. The model solutions exhibit a strong diversity concerning the averaged values and the temporal variations of the meridional volume and heat transports. The ocean reanalyses considered in this study, although constrained towards an observed ocean, do not converge towards the coherent large-scale climatic indices. These reanalyses are not coherent, neither between each other, nor compared to available observational estimations, underlying the difficulty to simulate coherent large-scale climatic indices with local data assimilation. Ce travail de thèse a pour objectif de caractériser et quantifier les différences entre indices climatiques océaniques grande échelle simulés par une hiérarchie de neuf modèles numériques océaniques réalistes (cinq simulations libres et quatre réanalyses). Cette étude se focalise sur la région Atlantique Nord. Les indices climatiques suivants : transport méridien de volume (circulation méridienne d'overturning) et transport méridien de chaleur sont diagnostiqués dans les différents modèles. La période commune à huit des simulations s'étend sur neuf ans, l'étude de la variabilité de ces indices climatiques se focalise sur l'echelle interannuelle. L'influence de différents paramètres numériques : configuration et la résolution spatiales des ...