Numerical modeling of turbulent melting dynamics:
application to sea-ice evolution in the Arctic
Location:
Laboratoire de Mecanique de Lille, University of Lille 1, France
Contacts:
Enrico Calzavarini (enrico.calzavarini@polytech-lille.fr)
Silvia Hirata (silvia.hirata@univ-lille1.fr)
Starting date: September 2014
Context, Objectives and Methodology
The extent of sea ice during summer in the Arctic Ocean is among the most sensitive indicators of the ongoing climate change.
During the last summers satellites have recorded an exceptional reduction of the Arctic sea-ice pack to an extent that none of the available large-scale numerical Global Climate models could predict. The observed ice loss has lead scietists to question their quantitative understanding of the dynamical and thermodynamical processes involved in the summer season melting and with it to reconsider several of the simplifying assumptions on which the current large-scale computer models are based.
Features related to water ponds forming over melted ice are too small to be directly accounted for in large-scale models. How does the heat transfer occur in the ponds and how does that affect the large-scale sea ice mass balance? How does the melt progress on the bottom and on the lateral walls of the ponds? How does the topography of the ponds, their surface and depth, evolve in the course of the summer season? All the above questions have been overlooked in the present models. Melt ponds and their surface topography are an important contributor to the surface albedo of the Arctic Ocean, which is a key factor for the global climate. Presently, the main challenge in sea ice climate science is to physically improve the models in order to refine their predictive power.
This research project addresses the problem of the growth process of ice melt ponds in the Arctic during the summer season by focusing on the small-scale (~ few meters) mechanisms controlling the evolution of the basin topography of a single melt pond. In particular we study the phenomenology of the thermal convective flow in the pond, which is known to be highly turbulent, and its interaction with the phase-change mechanisms at the pond boundaries.
The goal of the present project is to reach a sound understanding on how fluid dynamics and phase-change processes contribute in determing the pond growth in order to provide useful guidelines for parametrizations in large-scale models.
The proposed research is based on numerical simulations. A computational-fluid dynamics code is to be developed (using the Lattice-Boltzmann Method), in order to describe both the turbulent convective dynamics of melted water, with its inherent salt content, and the ice phase change under realistic conditions.
We shall then extend the small-scale simulation results to the medium and large scales. Our objective is to derive simplified parameterizations suitable for the implementation in large-scale ice-ocean models used for Earth System modelling.
Research group and funding
The project will be carried out in the Laboratoire de Mécanique de Lille (LML - Université Lille 1), with the supervision of Prof. Enrico Calzavarini (http://lmlm6-62.univ-lille1.fr/lml/perso/calzavarini/) and Prof. Silvia Hirata (http://lmlm6-62.univ-lille1.fr/lml/perso/hirata). The research group have a long and significant experience in computational fluid dynamics, turbulent mixing, convective flows, and transport phenomena through fluid and porous media.
The project will be carried out in close collaboration with Dr. Martin Vancoppenolle (CNRS), based at LOCEAN laboratory , Université Paris 6. Dr. Vancopenolle is a geophysicist specialized in the modelling and development of large-scale sea ice models (https://www.locean-ipsl.upmc.fr/~mvlod).
The PhD student will spend time in both labs to contribute to a shared development of a numerical tool capable of improving the understanding of melt ponds and sea-ice evolution during the Arctic summer.
The thesis falls within the framework of the SEAS project, funded by the ANR (Agence Nationale de la Recherche), the French National Research Agency.
Requirements
The candidate should have a background in fluid mechanics, as well as some experience in numerical methods and programming. A good knowledge of the English language will be appreciated.
How to apply
The applicant should send a motivation letter, a Curriculum Vitae, a transcript of his master grades, and a copy of his report of final master project.
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Silvia da Costa Hirata
Maître de Conférences à l'Université Lille 1
Laboratoire de Mécanique de Lille (LML)
Bâtiment M3, bureau 007
Boulevard Paul Langevin
59655 Villeneuve d'Ascq Cédex
Maître de Conférences à l'Université Lille 1
Laboratoire de Mécanique de Lille (LML)
Bâtiment M3, bureau 007
Boulevard Paul Langevin
59655 Villeneuve d'Ascq Cédex
France
Tél. : +33 (0)3 20 43 65 39
Fax : +33 (0)3 20 33 70 88
