BEGIN:VCALENDAR VERSION:2.0 PRODID:researchseminars.org CALSCALE:GREGORIAN X-WR-CALNAME:researchseminars.org BEGIN:VEVENT SUMMARY:Quanling Deng (ANU) DTSTART:20220802T060000Z DTEND:20220802T070000Z DTSTAMP:20260423T005844Z UID:anumacs/4 DESCRIPTION:Title: Superparameterisation of Arctic sea ice floes\nby Quanling Deng (ANU) as part of ANU Mathematics and Computational Sciences Seminar\n\nLecture h eld in Room 1.33\, Hanna Neumann Building #145.\n\nAbstract\nIn this talk\ , I will start with some quick facts about Arctic sea ice floes and then g ive a quick review of the evolution of sea ice models. The first models ar e Eulerian continuum models that describe the sea ice floes as viscous-pla stics (Hilber 1979). Lagrangian particle models have been developed recent ly\, showing improved model performance\, especially in ice-marginal zones where sea ice is fragmented. The most successful one is the discrete elem ent method (DEM). It characterises the physical quantities of each sea ice floe along its trajectory under the Lagrangian coordinates. The major cha llenges are 1) model coupling in different frames of reference (Lagrangian for sea ice while Eulerian for the ocean and atmosphere dynamics)\; 2) th e heavy computational cost when the number of the floes is large\; and 3) inaccurate floe parameterisation when the floe distribution has multiscale features. In this talk\, I will present a superfloe parameterisation to r educe the computational cost and a superparameterisation to capture the mu ltiscale features. The superfloe parameterisation algorithm generates a sm all number of superfloes that effectively approximate a considerable numbe r of the floes. The parameterisation scheme satisfies several important ph ysics constraints that guarantee similar short-term dynamical behaviour wh ile maintaining long-range uncertainties\, especially the non-Gaussian sta tistical features\, of the full system. In addition\, the superfloe parame terisation facilitates noise inflation in data assimilation that recovers the unobserved ocean field underneath the sea ice. To capture the multisca le features\, we follow the derivation of the Boltzmann equation for parti cles and superparameterise the sea ice floes as continuity equations gover ning the statistical moments of mass density and linear and angular veloci ties. This leads to a particle-continuum coupled model. The continuum part captures the large scales and the particle part captures the small scales . The particle model is localised and fully parallelised for computation e fficiency. I will present several numerical experiments to demonstrate the success of the proposed schemes. This is joint work with Nan Chen (UW-Mad ison) and Sam Stechmann (UW-Madison).\n LOCATION:https://researchseminars.org/talk/anumacs/4/ END:VEVENT END:VCALENDAR