Formation of condensation trails.
An experimental and theoretical investigation on the heterogeneous nucleation of atmospheric ice induced by soot emitted from jet airplane engines.

PhD student: Junteng WU

Context
Among other pollutants, jet aircraft engines release in the high troposphere soot aerosols that may act as ice/condensation nuclei for the heterogeneous nucleation of ice/supercooled water. The resulting condensation trails (contrails) may persist and even evolve to cirrus‑like clouds when the thermodynamic conditions are favorable, especially in high density air traffic regions. The formation of a cloud coverage induced by the air traffic has a potential impact on the energy balance of the atmosphere since it affects the local albedo, and therefore it should be considered in the energy balance of the atmosphere whenever estimating the human impact on climate.

Research goals
In this project we aim to provide information on the heterogeneous nucleation of ice particles and supercooled water droplets in jet aircraft condensation trails. This topic is critical to understand the impact of soot on the formation of atmospheric ice and therefore on the formation of contrails.

Research program
Most experiments will be run in the Lille Ice Nucleation Chamber (LINC), an experimental facility recently developed at PC2A to reproduce at the laboratory scale the heterogeneous nucleation of ice/water in conditions that mimic those of the high troposphere. In a typical experiment, soot aerosols simulating real airplane soot are injected into a low‑temperature environment at controlled ice/water supersaturations. The nucleation rates are then investigated as a function of physical and chemical properties of the seeding soot aerosol (size distribution, surface chemical composition and so on). Structure and morphology of the ice nuclei are investigated in parallel. The experimental data are expected to provide useful information on the heterogeneous processes involved in the ice/water nucleation and to validate theoretical models representative of the heterogeneous nucleation dynamic in the high troposphere.

This subject is part of a research network including at national level project MERMOSE of the Conseil Stratégique pour la Recherche Aéronautique Civile Française (CORAC), and at regional level projects LABEX CaPPA (http://labex-cappa.fr) and CPER CLIMIBIO.

Requirements
This project addresses to students already possessing a Master 2 or equivalent degree in Physics or Chemistry and especially motivated for experimental work. French and/or English are mostly spoken during daily activities.

Keywords
Aeronautics, climate, heterogeneous kinetics, thermodynamics.

Director: Pascale Desgroux (PC2A)
Co-director: Alessandro Faccinetto (PC2A)

Laboratory: PC2A

Financing: Région Nord-Pas-de-Calais / Labex CaPPA