BEGIN:VCALENDAR VERSION:2.0 PRODID:-//132.216.98.100//NONSGML kigkonsult.se iCalcreator 2.20.4// BEGIN:VEVENT UID:20250927T203243EDT-081157sL3G@132.216.98.100 DTSTAMP:20250928T003243Z DESCRIPTION:Numerical Instability in a Viscous Plastic Sea-Ice Model Arisin g from Unresolved Plastic Deformation\n\nThe plastic deformation wave in a viscous plastic sea-ice model travels at speeds greater than 25 m/s\, as shown by Gray. It is this wave which dictates\, in a CFL sense\, the maxim um allowable time step for a given model grid spacing. We find that typica l configurations of high resolution (dx=5km) sea-ice models require a time step of less than ~100 second to resolve the plastic deformation wave. Th e constraint on the timestep will become more strict as models continue to wards higher spatial resolution. We show that failure to correctly resolve this wave introduces first order noise into the model deformation fields and that the resulting error is exacerbated by use of the elastic-viscous- plastic integration technique. It is important that the model deformation fields be correctly resolved as they are increasingly being analyzed as a means to validate and compare different sea-ice rheologies. The underlying issue is the splitting in time of the sea-ice momentum and continuity equ ations\, resulting in a discrepancy between the sea-ice mass and momentum at a given model time step. We propose the IMplicit-EXplicit (IMEX) method for coupling the momentum and continuity equations as a way of correctly resolving the propagation of the plastic wave while maintaining a longer t ime step.\n DTSTART:20160217T200000Z DTEND:20160217T203000Z LOCATION:Room 934\, Burnside Hall\, CA\, QC\, Montreal\, H3A 0B9\, 805 rue Sherbrooke Ouest SUMMARY:Student Seminar: James Williams URL:/meteo/channels/event/student-seminar-james-willia ms-255075 END:VEVENT END:VCALENDAR