Multi-decadal to multi-secular hydroclimatic variability in the Arctic-subarctic since 2000 years

• Main Author: Nicolle, Marie
• Other Authors: Morphodynamique Continentale et Côtière (M2C), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS), Normandie Université, Nicolas Massei
• Format: Doctoral or Postdoctoral Thesis
• Language: French
• Published: HAL CCSD 2018
• Subjects: Arctic; Climate variability; Paleoclimate; Databases; Signal analysis; Arctique; Variabilité climatique; Paléoclimat; Bases de données; Analyse du signal; [SDU.STU]Sciences of the Universe [physics]/Earth Sciences; Pacific; Arctique*; North Atlantic; North Atlantic oscillation; Subarctic; subarctique*
• Online Access: https://theses.hal.science/tel-02076939; https://theses.hal.science/tel-02076939v2/document; https://theses.hal.science/tel-02076939v2/file/marienicolle2.pdf

The temperature increase during the 1850-2012 period is not uniform globally and the Arctic is warming twice as much as the average. However, the short time coverage of instrumental data makes it difficult to distinguish natural climate variability and anthropogenic forcing. The study of climatic variability "free" of human influence requires the use of proxies data measured in continental and marine palaeoclimatic archives. In the Arctic-subarctic region, high resolution records have been centralized in the Arctic 2k PAGES database. The objectives of this work are to improve the characterization and interpretation of climatic variability over the last 2000 years, going beyond the millennial trend and the major climatic periods, but also by focusing on the role and spatial expression of the internal variability of the climate system. This thesis is based on the Arctic 2k PAGES database, which allows the study of temperature variations in the Arctic-subarctic region, as well as a new database to reconstruct hydroclimatic variations (precipitation and humidity) in the region and created during this study. The use of climate signal analysis methods on regional records calculated from these two databases has highlighted climate variability in the Arctic-subarctic region from the multi-decadal to millennial scales.In particular, multi-decadal variability is related to the internal variability of the climate system. The hydroclimatic and temperature variations expressed at multi-decadal scales in the region are characterized by frequencies specific to regional climate oscillations (North Atlantic oscillation and decadal Pacific oscillation), particularly over the last 200 years. The work done on the temperature database and the reflection on the creation and exploitation of the hydroclimatic database have also led to the definition of a working methodology with a palaeoclimatic database, from its construction to the definition of its limits, in particular in terms of the spatial representability of the series ...