A Shared Atmosphere-Ocean Dynamical Core: First Validation (Semi-Implicit Semi-Lagrangian) Pierre Pellerin(2), François Roy(1,3), Claude Girard(2), François J. Saucier(3), and Hal Ritchie(2) (1)Ocean Science Branch, Maurice Lamontagne Institute, Department of Fisheries and Oceans, Mont-Joli, Québec, Canada (1)Ocean Science Branch, Maurice Lamontagne Institute, Department of Fisheries and Oceans, Mont-Joli, Québec, Canada (2)Recherche en Prévision Numérique, Service Météorologique du Canada, Dorval, Québec, Canada (3)Institut des Sciences de la Mer, Université du Québec à Rimouski, Rimouski, Québec, Canada

Introduction The idea of a common kernel for the atmosphere and the ocean using the semi-implicit semi-Lagrangian method implemented at CMC/RPN: Advantages and Motivations for Recherche en Prévision Numérique (RPN) and Environment Canada: -Complete a pilot study initiated by the late André Robert -The method is already implemented at the Canadian Meteorological Centre (CMC) and optimized for operational runs on super-computers -Something to offer to oceanographers in favor of technical and scientific collaborations -Possible access to numerical and scientific developments from oceanographers - Identify approach for GEM or other future models

Quasi-unified semi-discrete equations AIR buoyancy generalized buoyancy generalized pressure Water Ref: Girard et Al. 2005: MWR

Lobjet Solide (advection semi-lagrangienne) U U V V P U V V P U U V P U V P Grille Arakawa Type C Objet solide 2)Interpolations Actions: 1) 1)Calcul des trajectoires Conditions Miroirs

Lobjet Solide (advection semi-lagrangienne) U U V V P U V V P U U V P U V P Grille Arakawa Type C Objet solide 2) 2)Interpolations 3) 3)Solveur Équation Elliptique Actions: 1) 1)Calcul des trajectoires Pour UU selon un mur en x: Pour VV selon un mur en x: Free slip

Lobjet solide (les masques): U U V V P U V V P U U V P U V P Le masque pour UU Le Masque VV Le masque pour P, WZ,BB …

Lobjet solide (Comparaisons IML – RPN):

RPN EAU IML EAU UU VV

Solid Objects: Von Karman Vortex Streets Evaluation of 3 physical parameters.

Solid object (RPN/IML cf laboratory): Reynolds = 104 Stagnation points Separation points ~ 80 ° Kundu: Fluid Mechanics Von Karman vortex streets Kundu: Fluid Mec.

Flow around a cylinder (RPN model: RE=140)

Laboratory Re=140 Cylinder RPN Re=140 Cylinder Few Numerical noise => Allow to produce realistic vortex Few Numerical diffusion => Allow to maintain the vortex Laboratory Re=140 Cylinder RPN Re=140 Cylinder

Demonstration experiment: Oklahoma city (300 x 200 x 50), DX=DY=1.5 meters, dt=0.12 sec, 4000 timesteps