Abstract 

In this talk, I will start by presenting some quick facts about Arctic and Antarctic sea ice floes followed by a quick overview of the major sea ice continuum and particle models. I will then present our main contribution to its multiscale modelling.

The recent Lagrangian particle model based on the discrete element method (DEM) has shown improved model performance and started to gain more attention from the research groups that are working on Global Climate Models (GCMs). We adopt the DEM model for sea ice dynamical simulation. The major challenges are 1) model coupling in different frames of reference (Lagrangian for sea ice while Eulerian for the ocean and atmosphere dynamics); 2) the heavy computational cost when the number of the floes is large; and 3) inaccurate floe parameterisation when the floe distribution has multiscale features. To overcome these challenges, I will present a superfloe parameterisation to reduce the computational cost and a superparameterisation method to capture the multiscale features. In particular, the superfloe parameterisation facilitates noise inflation in data assimilation that recovers the unobserved ocean field underneath the sea ice. To capture the multiscale features, we adopt the Boltzmann equation for particles and superparameterise the sea ice floes as continuity equations governing the statistical moments. This leads to a particle-continuum coupled multiscale model. I will present several numerical experiments to demonstrate the success of the proposed method. This is joint work with Sam Stechmann (UW-Madison) and Nan Chen (UW-Madison).

About the speaker 

Quanling Deng

Australian National University

Dr. Quanling Deng is a Lecturer at the ANU School of Computing. He was born in Hunan, China and moved to the USA to study mathematics in August 2011. He graduated with a Ph.D. in computational mathematics with a topic on finite element analysis at the University of Wyoming in May 2016. He then joined Curtin University in Australia as a research associate and mainly contributed to the development of isogeometric analysis. He was a short-term visiting scholar at INRIA Paris, AGH University of Science and Technology in Poland, École des Ponts ParisTech (ENPC), USTC, and others. In March 2020, he joined the Department of Mathematics at the University of Wisconsin-Madison as a Van Vleck visiting assistant professor and worked on modelling and prediction of Arctic sea-ice dynamics. Dr. Deng has authored 35+ peer-reviewed publications. Also, he has given 15+ invited presentations and 20+ contributed talks at conferences and seminars and organised five mini-symposia at international conferences.