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Inclusion of the TEB urban canopy model in GEM and MC2 for atmospheric modeling at city scale

Inclusion of the TEB urban canopy model in GEM and MC2 for atmospheric modeling at city scale Aude Lemonsu. Remerciements : St é phane B é lair, Jocelyn Mailhot, Richard Hogue, Michel Jean

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Inclusion of the TEB urban canopy model in GEM and MC2 for atmospheric modeling at city scale

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  1. 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

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

  3. QH Industry QE Industry QH Traffic QE Traffic Town Energy Balance (TEB) (Masson 2000) • 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 Masson V, 2000: A physically-based scheme for the urban energy balance in atmospheric models. Bound.-Layer Meteor., 94, 357-397

  4. 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 z0m • 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

  5. Water Sea ice Urban Soil Vegetation Glaciers New type in the surface mosaic • Initial version of the Physics describes the surface like a mosaic of 4 different types of covers: • Soils and vegetation • Glaciers • Water • 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

  6. 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 Urban cover characterization (1) New 60-m land-use land-cover classification including 12 urban classes (Lemonsu et al. 2007) 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

  7. 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

  8. 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

  9. Ground truthing

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

  11. 1-km LULC global classification + Urban LULC classification 1-km LULC global classification UF07 UF09 VF26 VF26 UF10

  12. 1-km LULC global classification + Urban LULC classification 1-km LULC global classification UF07 UF09 VF26 UF10

  13. 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.ftncalled in inisurf1.ftn • The urban mask (UR, urban) is computed as the sum of the built-up fractions of the 12 urban classes

  14. Inclusion of TEB in the Physics (1) • 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.ftn90called in inisurf1.ftn • Physics: town.ftn90called 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

  15. Inclusion of TEB in the Physics (2) • 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: • Troof, Troad, Twall Roof, road and wall temperatures • Tcanyon, Qcanyon Canyon air temperature and humidity • WSroof, WSroad Roof and road water reservoir • Tibld Internal building temperature • Tiroad 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)

  16. Gulf of Mexico 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

  17. ANL CBD PNNL 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 Urban PWIDS network Soundings, sodars and radars upwind and downwind the CBD

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

  19. Numerical set-up (1) • 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 Lenderink, G. and Holtslag A.A.M., 2004: An updated lengthscale formulation for turbulent mixing in clear and cloudy boundary layers. QJRMS, 130, 3405-3427

  20. Numerical set-up (2) • 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 16 2003 • IOP9: nighttime period on July 26-27 2003

  21. Norman radiosounding (South of OKC) IOP6 July 16 1800 LST IOP9 July 27 0600 LST

  22. MESONET operation network IOP6 IOP9

  23. IOP6 IOP9 12 rural Stations (MESONET) IOP6 IOP9 13 urban Stations (PWIDS) IOP6 IOP9 Canopy level UHI Positive at night Negative at day

  24. Obs Model Urban effects at night 2100-2200 LST 0100-0400 LST PNNL upwind ANL downwind • Near-neutral layer observed at night in the first 300 m • ABL warmer downwind than upwind the CBD

  25. 21 22 23 00 01 02 03 04 05 06 Urban effects at night θ(50m) Vertical and horizontal structure of the UHI Δθ=θ(Urban)–θ(NoUrban) 50m acl - 0600 LST Δθ (oC) Δθ (oC) • Vertical extension of the UHI in the first 200 m • Decrease of the vertical extension during the night

  26. Urban No Urban 21 21 22 22 23 23 00 00 01 01 02 02 03 03 04 04 05 05 06 06 Urban effects at night θ(50m) Potential temperature anomaly Δθa=θ(City)–θ(Upwind) Δθa (oC) • Large-scale horizontal temperature gradient induced by the nocturnal Low Level Jet • Effect reinforced by the UHI near the surface

  27. Urban No Urban 21 21 22 22 23 23 00 00 01 01 02 02 03 03 04 04 05 05 06 06 Urban effects at night θ(50m) Potential temperature anomaly Δθa=θ(City)–θ(Upwind) Δθa (oC) • Large-scale horizontal temperature gradient induced by the nocturnal Low Level Jet • Effect reinforced by the UHI near the surface

  28. Next… 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

  29. 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

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

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

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