1. Funded by CRTI Project # 02-0093RD The current meteorological models can be run at high resolutions reaching a few hundreds of meters. Since the cities cover several grid points of the integration domain at such a scale, the impact of the urban radiative, energetic and dynamical processes must be taken into account in the computation of surface exchanges. Thus, the Meteorological Research Branch (MRB) of the Meteorological Service of Canada launched a large program in order to improve the representation of cities in the Canadian meteorological models including four main components: The implementation of a new urban parameterization requires to provide land-use classifications including specific urban covers in order to describe the spatial distribution and the diversity of urban areas. A methodology based on the joint analysis of satellite imagery (Landsat-7, Aster) and digital elevation models (SRTM-DEM, NED, CDED1) has been developed to produce 60-m resolution urban-cover classifications in a semi-automatic way for the main North American cities. The anthropogenic heat and humidity releases can be of major importance, more specifically during wintertime. The current version of TEB includes constant forcing of sensible and latent fluxes due to traffic and industrial activities. A methodology is under development to quantify in a more realistic way the anthropogenic sources asso- ciated to North American cities. Based on Sailor and Lu (2004), this method enables the estimation of the diurnal and seasonal cycles of releases due to metabolisms, traffic, and energy consumption. 60-m Montreal land-cover classification produced from the joint analysis of Landsat-7 and SRTM-DEM minus CDED1 High buildings Mid-high buildings Low buildings Very low buildings Sparse buildings Industrial areas Roads and parkings Road mix Dense residential Mid-density residential Low-density residential Mix of nature and built Deciduous broadleaf trees Short grass and forbs Long grass Crops Mixed wood forest Water Excluded Hourly fraction profiles for vehicular traffic in the United States (Sailor and Lu, 2004) D atabases The Montreal Urban Snow Experiment (MUSE) 2005 aimed to document the evolution of surface characteristics and energy budgets in a dense urban area during the winter-spring transition:  Evolution of snow cover from ~100% to 0% in an urban environment  Impact of snow on surface energy and water budgets  Quantification of anthropogenic fluxes in late winter and spring conditions  Evaluation of TEB in reproducing the surface characteristics and budgets in these conditions From March 17 th to April 14 th, continuous measurements were conducted to document: -Incoming and outgoing radiation -Turbulent fluxes by eddy-correlation -Radiative surface temperatures by thermal camera and infrared thermometers -Air temperature and humidity inside street and alley O bservations and Measurements Dense urban district of Montreal instrumented during MUSE During four intensive observational periods, manual measurements complemented the database: -Snow properties (depth, density albedo, surface temperature) -Radiative surface temperatures on various sites and urban elements -Photographs of street condition JD77JD79 JD81 JD83 JD85 Short-wave radiation budget and manual albedo measurements Thermal camera imagery – JD78 Roof with snow Roof without snow Street Sidewalk M odelling - Radiative trapping and shadow effect - Heat storage - Mean wind, temperature and humidity inside the street - Water and snow on roofs and roads - Mean urban canyon composed of 1 roof, 2 identical walls, 1 road - Isotropy of the street orientations - No crossing streets The Town Energy Balance (TEB) (Masson, 2000) has been recently implemented in the physics package of the Canadian meteorological models GEM and MC2.  Urban canopy model, dedicated to built-up covers, parameterizing water and energy exchanges between canopy and atmosphere  Three-dimensional geometry of the urban canopy for:  Idealized urban geometry i.e. Representation of the principal TEB scheme variables Q H top Q E top Q H traffic Q E traffic Q H industry Q E industry Q H roof Q E roof Water Snow T i bld T roof1 T roof2 T roof3 T wall1 T wall2 T wall3 T road1 T road2 T road3 SnowWater Q H road Q E road T canyon q canyon Q H wall Q E wall R roof R wall R roof Snow R road R road Snow R top Atmospheric level Input data Prognostic variables Diagnostic variables U a, T a, q a Meso-γ and offline Regional NWPMUSE II MUSE TEB urban scheme 3d-turbulence Surface fields Anthropogenic heat sources ModellingDatabasesTransferObservations A. Lemonsu 1, S. Bélair 1, J. Mailhot 1, N. Benbouta 2, M. Benjamin 3, F. Chagnon 2, M. Jean 2, A. Leroux 2, G. Morneau 3, C. Pelletier 1, L. Tong 4, S. Trudel 2 Environment Canada; 1 MSC, Meteorological Research Branch; 2 MSC, Environmental Emergency Response Division; 3 Quebec Region; 4 MSC, Development Branch RMetS Conference 2005 Poster 940 Environment Canada Environnement Canada For high resolution modelling application (less than 1 km), the Reynolds time-averaged form of the compressible Navier-Stokes equations and the generalized 3D budget TKE equation have been introduced in MC2. This implementation will also be done in GEM soon. Extensive evaluation of the “urbanized” version of the model against observations is currently performed within the framework of the Joint Urban 2003 experiment (Oklahoma City, OKC, US). The first results are encouraging giving the fact that TEB has never been tested over North American city centers. 2-m air temperature modelled by the 1-km offline version of GEM including TEB 299 300 301 302 303 304 0713190107 Time (Hour LST) Observations Model without TEB Model with TEB 20 25 30 35 40 45 Temperature ( o C) Air temperature inside the streets observed during Joint Urban 2003 and modelled by the 200-m offline version of GEM with and without TEB July 17 th 0000LST