Variability of the atmospheric hydrological cycle in polar regions through water stable isotopes measurements in vapor, precipitation and firn cores

• Main Author: Leroy-dos Santos, Christophe
• Other Authors: Laboratoire des Sciences du Climat et de l'Environnement Gif-sur-Yvette (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Université Paris-Saclay, Amaëlle Landais
• Format: Doctoral or Postdoctoral Thesis
• Language: French
• Published: HAL CCSD 2021
• Subjects: Antarctica; Arctic; Water stable isotopes; Atmospheric dynamic; Hydrological cycle; Antarctique; Arctique; Isotopes stables de l'eau; Dynamique atmosphérique; Cycle hydrologique; [SDU.OCEAN]Sciences of the Universe [physics]/Ocean; Atmosphere; [SDU.STU.HY]Sciences of the Universe [physics]/Earth Sciences/Hydrology; Antarctic; Antarc*; Antarctique*; Arctique*; Global warming
• Online Access: https://tel.archives-ouvertes.fr/tel-03214337; https://tel.archives-ouvertes.fr/tel-03214337/document; https://tel.archives-ouvertes.fr/tel-03214337/file/97990_LEROY_2021_archivage.pdf

In a global warming context, understanding the evolution of sea level rise is a major challenge. It is key to estimate the evolution of the atmospheric hydrological cycle in the polar regions, which directly influences the surface mass balance of the Arctic and Antarctic ice caps (the two largest freshwater reservoirs on the planet). Records are available from satellite data for the last 50 years and a few rare weather data since the 50's in Antarctica, but these records are too short to study the patterns of interannual variability and the difference between anthropogenic and natural signals. One of the best ways to access longer records is to use climate proxies in snow cores. The water isotopic composition in these cores is widely used to reconstruct past temperature variations. However, the link between temperature and isotopic composition is not very well constrained because many other parameters influence the isotopic composition of snow at the time of its formation (i.e. temperature, altitude, humidity, origin of the air mass) or after snow deposition on the surface (i.e. atmosphere-snow exchange, signal scattering, sublimation of surface snow).The objective of this thesis is to better understand the atmospheric hydrological cycle and its influence on the isotopic composition of vapour and precipitation in polar regions with the idea of improving the interpretation of snow core records in these regions. This work is divided into 3 parts.Firstly, we developed a technical solution to meet the challenge of measuring the vapor isotopic composition all year round in polar regions. Indeed, winter being very dry in these regions (down to 10 ppmv at Dome C in winter), the use of a Picarro laser analyzer is limited because it is very sensitive to humidity variations below 2000 ppmv. Winter is a key season in the polar regions as it is associated with significant climate variability due to numerous synoptic events. During this thesis, the fabrication of 2 prototypes of low humidity level generator (LHLG) allowed ...