On the role of the ice phase on the life cycle of clouds and their microphysical and optical properties : contribution of in situ observations

• Main Author: Jourdan, Olivier
• Other Authors: Laboratoire de Météorologie Physique (LaMP), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA), Université Clermont Auvergne, Frédéric Szczap
• Format: Doctoral or Postdoctoral Thesis
• Language: French
• Published: HAL CCSD 2022
• Subjects: Cloud microphysics; airborne measurements; light scattering properties; Microphysique de nuages; mesures aéroportées; propriétés de diffusion simple; [PHYS.PHYS.PHYS-AO-PH]Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph]; [SDU.STU.ME]Sciences of the Universe [physics]/Earth Sciences/Meteorology; Arctic; Svalbard
• Online Access: https://theses.hal.science/tel-04122883; https://theses.hal.science/tel-04122883/document; https://theses.hal.science/tel-04122883/file/HDR_OJourdan_LaMP_2022.pdf

Clouds play a crucial role to regulate the surface energy budget with competing warming and cooling effects. The life cycle of stratiform clouds results from a complex web of interactions between local microphysical, radiative, dynamical processes and larger scale environmental conditions. Ice containing clouds are challenging to model from small to global scales and strong assumptions in the representation of the microphysical processes are required. This habilitation thesis summarizes part of the main findings on mid latitude cirrus and arctic mixed phase clouds microphysical and optical properties achieved using in situ and active remote sensing observations. The first part of this manuscript deals with cloud chamber experiments we carried out to study the microphysical processes involved in the life cycle of ice crystals. The impact of the morphological structure of hydrometeors on their optical properties is also addressed using an approach combining observations and light scattering modelling. The second part focuses on the in situ characterization of upper tropospheric ice clouds (cirrus clouds and aircraft contrails) during mid-latitudes airborne campaigns. This section also discusses the contribution of these observations to the study of cirrus clouds-radiation interactions. The third part of this document is dedicated to mixed-phase clouds, particularly present in the lower layers of the Arctic atmosphere. Active remote sensing satellite observations (radar/lidar) are used to document and analyze the geographical and seasonal distributions of these clouds. The influence of environmental conditions on the vertical variability of mixed-phase cloud microphysical properties and hydrometeor growth processes is then studied using airborne measurements carried out in the Svalbard region. These observations are used to establish microphysical and optical parameterizations for models, and to evaluate satellite inversion algorithms. Finally, the last section describes the main scientific directions I intend to ...