Inclusion of the TEB urban canopy model in GEM and MC2 for atmospheric modeling at city scale Aude Lemonsu Remerciements : Stéphane Bélair, Jocelyn Mailhot, Richard Hogue, Michel Jean Gianpaolo Balsamo, Najat Benbouta, Bernard Bilodeau, Mario Benjamin, Frédéric Chagnon, Stéphane Chamberland, Michel Desgagné, Jean-Philippe Gauthier, Bruno Harvey, Vivian Lee, Alexandre Leroux, Gilles Morneau, Radenko Pavlovic, Pierre Pellerin, Sarah Roberts, Lubos Spacek, Linying Tong, Serge Trudel, Michel Valin, James Voogt, Yufei Zhu

Overview 1.Town Energy Balance (TEB) 2.Inclusion of TEB in GEM and MC2 3.Evaluation of the urban modeling system 4.Next …

 Urban canopy model for parameterization of water and energy exchanges between canopy and atmosphere  Model specifically designed for built-up covers  3D but idealized geometry - Mean urban canyon - Isotropy of street orientations - No crossing streets  Specific processes inside canopy - Radiation trapping + shadow effect - Heat storage - Urban microclimate inside the street  Independent treatment of urban facets - Independent surface energy balance - Water and snow on roofs and roads Town Energy Balance (TEB) Q H Traffic Q E Traffic Q H Industry Q E Industry Masson V, 2000: A physically-based scheme for the urban energy balance in atmospheric models. Bound.-Layer Meteor., 94, (Masson 2000)

How to include cities in GEM & MC2? Current versions of GEM and MC2 do not include specific parameterization for built-up covers GEM and MC2 use a 1-km global LULC classification which includes 1 “URBAN” cover type (defined from the Digital Chart of the World, Danko 1992) Cities can be represented by sand + large z 0m  Urban covers must be taken into account as an independent type associated with its own surface scheme  Higher accurate urban LULC classifications are required to document spatial variability and diversity of urban landscapes Danko D M, 1992: The digital chart of the world. GeoInfo Systems, 2, 29-36

 Initial version of the Physics describes the surface like a mosaic of 4 different types of covers: (1)Soils and vegetation (2)Glaciers (3)Water (4)Continental ice + (5)Aggregation  Each type is associated with a specific surface scheme  The fluxes are aggregated according to the fractions of each type  The inclusion of TEB in the Physics requires an additional type corresponding to built-up covers New type in the surface mosaic Sea ice Soil Vegetation Glaciers Water Urban

Urban cover characterization (1) New 60-m land-use land-cover classification including 12 urban classes (Lemonsu et al. 2007) High buildings Mid-high buildings Low buildings Very low buildings Sparse buildings Industrial areas Roads and parking lots Road mix Dense residential Mid-density residential Low-density residential Mix of nature and built Montreal 60m LULC classification Lemonsu A, Leroux A, Bélair S, Trudel S, and Mailhot J, 2007: A general methodology of urban cover classification for atmospheric modelling, JAMC, in revision

Urban cover characterization (1) New 60-m land-use land-cover classification including 12 urban classes Each urban class is an arrangement of built-up covers and vegetation The vegetated part can be decomposed in three different types: (1) trees, (2) grass, and (3) bare soil A look-up table defines a set of parameters for each urban class: -fractions of built-up and natural covers -fractions of trees, grass and bare soil -building fraction -building height -roughness length for momentum -canyon aspect ratio -ratio wall/plane built surfaces -albedo and emissivity of roofs, roads, and walls -thermal properties of roofs, roads, and walls

Urban cover characterization (2) The urban LULC classification is only produced for limited urban areas. It has to be coupled with the 1-km global LULC database The new geophysical fields include: VF (vegf)- fractions of the 26 classes of water, natural soils and vegetation - normalized UF (urbf)- fractions of the 12 urban classes - not normalized - including fractions of vegetated covers

Ground truthing

UF09 UF10 UF07 VF26 1-km LULC global classification Urban LULC classification

UF09 UF10 UF07 VF26 1-km LULC global classification VF26 1-km LULC global classification + Urban LULC classification

UF09 UF10 UF07 VF26 1-km LULC global classification + Urban LULC classification

Urban cover characterization (2) The urban LULC classification is only produced for limited urban areas. It has to be coupled with the 1-km global LULC database The new geophysical fields include: VF (vegf)- fractions of the 26 classes of water, natural soils and vegetation - normalized UF (urbf)- fractions of the 12 urban classes - not normalized - including fractions of vegetated covers 38 new cover fractions (6F, covf) are computed in the new routine calccovf.ftn called in inisurf1.ftn The urban mask (UR, urban) is computed as the sum of the built-up fractions of the 12 urban classes

Inclusion of TEB in the RPN physics package is done by avoiding modifying the original version of the TEB’s code as much as possible TEB is “plugged” to the Physics using two interface routines: - Initialization: initown.ftn90 called in inisurf1.ftn - Physics: town.ftn90 called in surface.ftn These interface routines allow the transfer of the variables from the physics’ buses to the TEB’s code and inversely A new key is included in the namelist &gement of gem_settings.nml P_pbl_schmurb_s = ‘TEB’ (or ‘NIL’ ) TEB’s code is already part of Physics v4.4 and is compatible with GEM v3.2.2 and MC2 v4.9.8 Inclusion of TEB in the Physics (1)

 TEB’s input parameters (geometric parameters + material properties) are defined using the look-up table associated with the urban LULC classification  TEB’s prognostic variables: T roof, T road, T wall Roof, road and wall temperatures T canyon, Q canyon Canyon air temperature and humidity WS roof, WS road Roof and road water reservoir Ti bld Internal building temperature Ti road Deep road temperature Snow variables for roofs and roads -Initialized using other analyses (e.g. TT, TS, HU, …), if not available in the forcings -Read in the analysis field if available (e.g. Cascade run) Inclusion of TEB in the Physics (2)

Evaluation of the urban modeling system Joint Urban 2003 (Allwine et al. 2004) is an atmospheric dispersion study held in Oklahoma City in July 2003 Gulf of Mexico

Urban PWIDS network Evaluation of the urban modeling system Joint Urban 2003 (Allwine et al. 2004) is an atmospheric dispersion study held in Oklahoma City in July 2003 CBD ANL PNNL Soundings, sodars and radars upwind and downwind the CBD

GEM-LAM 2.5km, 200x200 GEM-LAM 1km, 200x200 GEM-LAM 250m (IOP6), 200x400 GEM-LAM 250m (IOP9)

 Boundary and initial condition of 2.5km GEM-LAM provided by GEM-regional model  2.5km GEM-LAM’s configuration = quasi-operational version  Mixing length calculated using: - Lenderink and Holtslag (2004) formulation for 2.5km and 1km GEM-LAM - Formulation derived from Blackadar and based on the grid size for 250m GEM-LAM  Vertical grid: - 58 levels (first level at 40 m above canopy level) for 2.5km GEM-LAM - More detailed inside the atmospheric boundary layer for 1km and 250m GEM-LAM Numerical set-up (1) Lenderink, G. and Holtslag A.A.M., 2004: An updated lengthscale formulation for turbulent mixing in clear and cloudy boundary layers. QJRMS, 130,

 Surface schemes: - ISBA for vegetation and natural soils - TEB for built-up covers  Sensitivity tests: - Urban simulation:with TEB - No Urban simulation:city replaced by vegetation  Numerical integrations - IOP6: daytime period on July IOP9: nighttime period on July Numerical set-up (2) Model Starting dateIntegration Timestep IOP6IOP9IOP6IOP9 GEM-regional hr36hr450s 2.5km GEM-LAM hr30hr60s 1km GEM-LAM hr 30s 250m GEM-LAM hr 10s

IOP6 July LST Norman radiosounding (South of OKC) IOP9 July LST

IOP6 IOP9 MESONET operation network

12 rural Stations (MESONET) 13 urban Stations (PWIDS) Canopy level UHI Positive at night Negative at day IOP6IOP9 IOP6IOP9 IOP6IOP9

LST LST PNNL upwind ANL downwind Urban effects at night  Near-neutral layer observed at night in the first 300 m  ABL warmer downwind than upwind the CBD Obs Model

Urban effects at night Vertical and horizontal structure of the UHI Δθ = θ(Urban) – θ(No Urban) Δθ ( o C) 50m acl LST  Vertical extension of the UHI in the first 200 m  Decrease of the vertical extension during the night θ (50m)

Urban effects at night Potential temperature anomaly  Large-scale horizontal temperature gradient induced by the nocturnal Low Level Jet  Effect reinforced by the UHI near the surface Δθa = θ(City) – θ(Upwind) UrbanNo Urban Δθa ( o C) θ (50m)

Urban effects at night Potential temperature anomaly  Large-scale horizontal temperature gradient induced by the nocturnal Low Level Jet  Effect reinforced by the UHI near the surface Δθa = θ(City) – θ(Upwind) Δθa ( o C) θ (50m) No UrbanUrban

CRTI Project: Weekly GEM-LAM simulations using the prototype configuration for the cities of Montreal and Vancouver Collaborative research network on Environmental Prediction in Canadian Cities (EPiCC) funded by the CFCAS:  Canadian optimized version of TEB-ISBA taking into account the specifics of Canadian cities -Building materials -Vegetation -Snow and cold winter conditions  Modeling studies of the urban boundary layer over Montreal Next…

TEB offline evaluation for MUSE 2005 MUSE 2005 documents the evolution of surface characteristics and energy budgets in a dense urban area during the winter- spring transition (17 March - 14 April 2005) Lemonsu A, Bélair S, Mailhot J, Benjamin M, Chagnon F, Morneau G, Harvey B, Voogt J, Jean M, 2007: Overview and first results of the Montreal Urban Snow Experiment (MUSE) 2005, JAMC, in revision

TEB offline evaluation for MUSE 2005 Air canyon temperature Radiative surface temperatures (Walls)

Net all-wave radiation Sensible heat flux Latent heat flux Residue Obs Model