nouveau Mod ele Canadien de Climat Rà egional (MCCR). La formulation du MCCR re- IntroductionThe last quarter of the century has witnessed important progress in the performance and achievements of global forecast and climate models. This progress is based on more accurate and efþcient numerical methods, more comprehensive parametrization of the ensemble effects of unresolved physical processes upon the resolved part of the ow, more sophisticated programming techniques to speed-up execution of computer programs and þnally { but not least { increased resolution afforded by faster computers. Together with improved model initialization and data assimilation methods, this evolution has led to better weather analyses and short-term forecasts. The increasing ability of global models to reproduce complex phenomena that operate on longer timescales, such as the ENSO (El Niño { Southern Oscillation), lends conþdence to the possibility of achieving seasonal dynamical extended-range forecasts. General Circulation Models (GCMs) have evolved from the initial purely atmospheric models into Global Climate Models which include oceans, sea-ice and land-surface processes as well as detailed physical parametrizations of subgrid-scale phenomena. Serving as computerized experimentation laboratories, such models constitute useful tools to further our understanding of climate as a physical system with multiple interacting processes.Numerical Weather Prediction (NWP) and climate models differ in a number of ways, resolution being one of the most obvious. Nowadays NWP centres operate global models with computational meshes of the order of one hundred kilometres, whereas the resolution of GCMs typically used for climate simulations is coarser by about a factor of three or þve or even more. This coarser resolution is imposed by computational constraints associated with the very long simulations (on timescales of decades to centuries) required for climate studies, as opposed to days for forecasts. The computing cost of a global model increases by more than two orders of magnitude for a factor of 5 increase in resolution. Lesser resolution is hence a

ABSTRA~ A description of the numerical formulation of the dynamics module of the Mesoscale Compressible Commun@ (MC') mode1 is presented. This mode1 is based on the fülly elastic, semi-implicit semi-Lagrangian mode1 developed by Tanguay et al. (1990). This version was extended to incorporate topography by Denis (1990), and later variable vertical resolution was added as an option. This article is a condensed version of an extensive report by Bergeron et al. (1994) that documents a11 the numerical aspects of the tUC2 model. The performance of the mode1 is illustrated through a sample of results obtained on a wide range of physical problems.RÉSUMÉ Cet article présente une description de la formulation numérique du module de la dynamique du modèle de mésoéchelle compressible communautaire (Mê). Ce modèle est basé sur les équations pleinement élastiques qui sont solutionnées par les schémas semiimplicite et semi-lagrangien comme dans Tanguay et al. (1990). La présente version incorpore la topographie comme dans Denis (1990), et elle permet l'utilisation d'un étirement de la maille verticale. Cet article constitue un condensé du volumineux rapport de Bergeron et al. (1994) qui décrit tous les divers aspects numériques du modèle MC'. La performance du modèle est illustrée avec un échantillon de résultats obtenus sur une grande variété de problemes physiques.

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The Canadian Regional Climate Model (CRCM)

Although not very common, forensic investigation related to projectile ricochet on water can be required when undesirable collateral damage occurs. Predicting the ricochet behavior of a projectile is challenging owing to numerous parameters involved: impact velocity, incident angle, projectile stability, angular velocity, etc. Ricochet characteristics of different projectiles (K50 BMG, 0.5-cal Ball M2, 0.5-cal AP-T C44, 7.62-mm Ball C21, and 5.56-mm Ball C77) were studied in a pool. The results are presented to assess projectile velocity after ricochet, ricochet angle, and projectile azimuth angle based on impact velocity or incident angle for each projectile type. The azimuth ranges show the highest variability at low postricochet velocity. The critical ricochet angles were ranging from 15 to 30°. The average ricochet angles for all projectiles were pretty close for all projectiles at 2.5 and 10° incident angles for the range of velocities studied.