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“CITES-2005” Novosibirsk, Russia, March 13-19, 2005

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1 “CITES-2005” Novosibirsk, Russia, March 13-19, 2005
Lectures course “Meteorology applied to Urban Air Pollution Problems” Alexander Baklanov, Danish Meteorological Institute Young Scientists School on Computational Information Technologies for Environmental Sciences: “CITES-2005” Novosibirsk, Russia, March 13-19, 2005

2 Meteorology applied to Urban Air Pollution Problems: Lecture schedule
Четверг. 17 марта 2005 года 11:00 – 13:00 Лекционные курсы (К/З ИВМиМГ) 2. Meteorology applied to Urban Air Pollution Problems. Alexander Baklanov (Danish Meteorological Institute, Denmark) 13:00 – 14:30 – Обед 14:30 – 15:30 - Лекционные курсы 3. Meteorology applied to Urban Air Pollution Problems. Alexander Baklanov (Danish Meteorological Institute, Denmark) 15:30 - Практические занятия (компьютерные классы ИВМиМГ, ИВТ СО РАН) Пятница. 18 марта 2005 года 9:00 – 13:15 Лекционные курсы (К/З ИВМиМГ) 1. Meteorology applied to Urban Air Pollution Problems. Alexander Baklanov (Danish Meteorological Institute, Denmark) 11:00 – 11:15 - Перерыв 2. Meteorology applied to Urban Air Pollution Problems. Alexander Baklanov (Danish Meteorological Institute, Denmark) 13:15 – 14:30 – Обед Посещение РЦ ПОД Отчеты групп о выполнении практических заданий

3 Structure of the Lectures
Introduction to European research (COST Actions 710, 715, 728, 732, SATURN/EUROTRAC, CLEAR cluster, ACCENT, etc.) Structure of the urban boundary layer Modification of flow and turbulence structure over urban areas The surface energy balance in urban areas The mixing height and inversions in urban areas Evaluation and analysis of European peak pollution episodes European urban experiments (Copenhagen, ESCOMPTE, BUBBLE, etc.) Preparation of meteorological input data for urban air pollution models Integrated modelling : Forecasting Urban Meteorology, Air Pollution and Population EXposure (FUMAPEX) and COST 728 Summary of achievements, gaps in knowledge, recommendations for further research

4 Why Urban Meteorology Now?
Erik Bødtker, Danmarks Meteorologiske Institut 11/04/2017 Why Urban Meteorology Now? Technological Advances Remote sensing and other platforms Computer models Homeland Security Atmospheric Transport and Diffusion (ATD) models Health and Safety High impact weather Air quality Technology Advances - computing power, data collections, communications capabilities, better understanding of the science, and support for these programs are now available H.S attacks pointed to our vulnerability and our urban areas are where people congregate and are a target for terrorist. This has brought back to our attention again the need for ATD models. These our building off our experience in the Cold War and for supporting activities in Dept. of Energy with our Nuclear Power Plants. Health and Safety - we are just now beginning to understand the health hazards of bad air. As people congregate in urban areas, this is also were a lot of the chemicals made by man collect – air pollution. There is a use for additional air quality information to help mitigate health impacts High Impact Weather – includes heat waves are major killers for urban areas, hurricanes, tornadoes, severe thunderstorms, winter weather with its ice storms, snow, wind and cold outbreaks.

5 Erik Bødtker, Danmarks Meteorologiske Institut
11/04/2017 Why do we have to consider the urban effects? What kind of effects?

6 Urban BL features: Local-scale inhomogeneties, sharp changes of roughness and heat fluxes, Wind velocity reduce effect due to buildings, Redistribution of eddies due to buildings, large => small, Trapping of radiation in street canyons, Effect of urban soil structure, diffusivities heat and water vapour, Anthropogenic heat fluxes, urban heat island, Internal urban boundary layers (IBL), urban Mixing Height, Effects of pollutants (aerosols) on urban meteorology and climate, Urban effects on clouds, precipitation and thunderstorms.

7 Erik Bødtker, Danmarks Meteorologiske Institut
11/04/2017 A city can be considered as a protect area for meso scale atmospheric events : Urban heat island has a positive influence in the winter outdoor thermal comfort and the energy consumption Urban roughness mitigates wind speed actions on tall buildings above the mean roof level But At small scale in the urban canopy, the built environment can induce negative effects: over speed area around buildings low diffusion of pollutants in street canyon Lack of ventilation for indoor and outdoor comfort

8 Erik Bødtker, Danmarks Meteorologiske Institut
11/04/2017 Example: effects of storm Lothar (1999) Buildings located downwind of small roughness (sea and open country) had more damages on structure Wind effects on structure % of damages sea Open country urban suburbs

9 The Urban System (EU 5FP City of Tomorrow)
Interactions between the city, human environment and biophysical environment INPUTS Energy Money Food Information Water Raw Materials Manufactured goods HUMAN THE CITY BIOPHYSICAL ENVIRONMENT ENVIRONMENT People Physical Structure Atmosphere & Energy Flows Ethnicity Building Type Hydrological Cycle Politics Layout Soils, Vegetation, Fauna Technology Geology & Landforms OUTPUTS Wastes Employment Liquids Wealth Solids Manufactured Goods Gases Degraded Energy LINKS TO Urban Systems OTHER Rural Systems Regions Transport Communication From Bridgman et al. (1996)

10 Introduction to European research
COST Actions 710, 715, 728, 732, SATURN/EUROTRAC/TRAPOS, CLEAR cluster, FUMAPEX project, ACCENT Network of Excellence, WMO GURME project US EPA/NOAA projects

11 Erik Bødtker, Danmarks Meteorologiske Institut
11/04/2017 COST - European Co-operation in the field of Scientific and Technical Research (http://cost.cordis.lu/src/domain_detail.cfm?domain=7) Domain: Meteorology Harmonisation in the pre-processing of meteorological data for dispersion models – COST710 In the framework of COST, there has been an international action, COST 710, aimed at Harmonisation in the pre-processing of meteorological data for dispersion models. COST 710 has been followed by a related action, COST 715, concerning Urban Meteorology applied to Air Pollution Problems. A somewhat related action, COST 732, will be carried out from 2005 onwards. COST 732 is entitled Quality Assurance and Improvement of Microscale Meteorological Models. Meteorology applied to Urban Air Pollution Problems  -  COST 715 In the framework of COST, an international action has been conducted aimed at increasing knowledge of, and the accessibility to, the main meteorological parameters which determine urban pollution levels. The action was designated initiated COST 715. COST 715 follows a previous action, COST 710.

12 Erik Bødtker, Danmarks Meteorologiske Institut
11/04/2017 Meteorology applied to Urban Air Pollution Problems  -  COST 715 (1998 – 2004)  Working Group 1: Urban wind field  Working Group 2: Energy Budget and the Mixing height in Urban Areas Working Group 3: Meteorology during peak pollution episodes Working Group 4:  Input Data for Urban Air Pollution Models

13 Working Group 1: Urban wind field
Erik Bødtker, Danmarks Meteorologiske Institut 11/04/2017 Working Group 1: Urban wind field Goals Review and evaluate methods to describe and parameterise the wind field over urban areas from routine meteorological observations: near-surface conditions (roughness sublayer) profile throughout the UBL possibly: distinction between different locations within a city recommendations on what /how Met. Services (and others) should measure in urban areas Methods Review existing methods (theories) for the specific goals above identify existing data sets for the specific goals above identify new data sets develop general semi-empirical relationships for the description of the UWF and related parameters Plans In the longer term, seeking new directions for developing a theory for the urban wind profile Evaluation of the role of alternative tools such as numerical models or remote sensing techniques

14 Erik Bødtker, Danmarks Meteorologiske Institut
11/04/2017 Working Group 2:   The Surface Energy Budget and the Mixing height in Urban Areas Background Urban pollution meteorology is characterised by a number of fundamental parameters and their evolution in time, which all have specific problems as to their monitoring, representativeness, parameterisation and modelling.  Within COST-715, WG2 addresses the specific problems in describing the surface energy balance and the mixing height. The surface energy balance and the surface temperature and heat fluxes determine the hydrostatic stability conditions in the lower atmosphere and regulate its strength for mixing pollutants, the mixing height parameter determines the available volume for pollutants mixing. The activities of WG2: To review theoretical concepts of the structure of the urban boundary layer. To review and assess pre-processors, schemes and models for determining the mixing height, the surface energy budget and the stability that are available to the participants. Cases of strong stability and/or windless conditions are of special interest. To review theoretical models together with available field measurements and LES for calculation of the minimum friction velocity and the heat transfer coefficient. Conditions of shear free convection over high roughness are of main importance To identify and review suitable data sets within and outside the group that could be used to test and validate the pre-processors and models. To carry out intercomparisons and to summarise comparisons of different schemes against each other and against data under specific conditions. To assess the influence of the model outputs of certain specific effects such as complex topography, strong heterogeneity, slope effects and canopy trapping on radiative fluxes. To assess the suitability of remote sensing tools to estimate canopy characteristics and surface fluxes. To provide recommendations for the improvement of existing pre-processors and models and for the development of new schemes. To provide recommendations for planning and conducting field campaigns in order to fill the important existing gaps for empirical data of key parameters for urban air pollution. To promote co-ordination of related activities in Europe of presently scattered works, objectives, and responsibilities.

15 Erik Bødtker, Danmarks Meteorologiske Institut
11/04/2017 Working Group 3: Meteorology during peak pollution episodes During air pollution episodes pollutant concentrations are highest, and the related adverse health impact on the public should therefore be reliably evaluated. The meteorological conditions prevailing in the course of episodes are at the same time commonly the most difficult to model with the computing tools presently available. European Union nevertheless requires practical measures to be taken, if air quality limit values are exceeded.

16 CLEAR Cluster of European Air Quality Research
Coordinator: Prof. Ranjeet S Sokhi Atmospheric Science Research Group (ASRG) University of Hertfordshire, UK Scientific Officer: Viorel Vulturescu European Commission, DG Research Launched: December 2002

17 Aim of CLEAR Threefold aim:
To improve our scientific understanding of atmospheric processes, composition and pollution variabilities on local to regional scales To provide next generation tools for end users and stakeholders for managing air pollution and responding to its impact To help create a critical mass of expertise and ambition to address future research needs in the areas of air pollution, its impact and response strategies.

18 Eleven Participating Projects FP5, EESD, City of Tomorrow
ATREUS (Coordinator: Dr Agis Papadopoulos, University of Thessaloniki) – Human Potential Research network - Advanced Tools for Rational Energy Use towards Sustainability with emphasis on microclimatic issues in urban applications OSCAR (Coordinator: Professor Ranjeet S Sokhi, University of Hertfordshire) - Optimised Expert System for Conducting Environmental Assessment of Urban Road Traffic FUMAPEX (Coordinator: Dr Alexander Baklanov, DMI) Integrated Systems for Forecasting Urban Meteorology, Air Pollution and Population Exposure ISHTAR (Prof Emanuele Negrenti, ENEA) - Integrated Software for Health, Transport efficiency and Artistic heritage Recovery

19 Eleven Participating Projects FP5, EESD, City of Tomorrow
SAPPHIRE (Coordinator: Dr Stuart Harrad, University of Birmingham) - Source Apportionment of Airborne Particulate Matter and Polycyclic Aromatic Hydrocarbons in Urban Regions of Europe URBAN AEROSOL (Professor Mihalis Lazaridis, Technical University of Crete) Characterisation of Urban Air Quality Indoor/Outdoor Particulate Matter Chemical Characteristics and Source-to-Inhaled Dose Relationships URBAN EXPOSURE (Dr Trond Bohler, NILU) Integrated Exposure Management Tool Characterising Air Pollution Relevant Human Exposure in Urban Environment

20 Eleven Participating Projects FP5, EESD, City of Tomorrow
BOND (Coordinator: Professor John Bartzis, NCSRD) Biogenic Aerosols and Air Quality in the Mediterranean Area MERLIN (Coordinator: Professor Rainer Friedrich, University of Stuttgart) Multi-pollutant, Multi-Effect Assessment of European Air Pollution Control Strategies: an Integrated Approach AIR4EU (Coordinator: Professor Peter Biltjes, TNO) – FP6 Project Air Quality Assessment for Europe: Local to Continental Scales INTEGAIRE (Coordinator: Dr Eva Banos, EUROCITIES) - Integrated Urban Governance and Air Quality Management in Europe

21 CLEAR 20 Partner Countries

22 FUMAPEX: Integrated Systems for Forecasting Urban Meteorology, Air Pollution and Population Exposure Project objectives: the improvement of meteorological forecasts for urban areas, the connection of NWP models to urban air quality (UAQ) and population exposure (PE) models, the building of improved Urban Air Quality Information and Forecasting Systems (UAQIFS), and their application in cities in various European climates.

23 UAQIFS: Scheme of the suggested improvements of meteorological forecasts (NWP) in urban areas, interfaces to and integration with UAP and PE models

24 FUMAPEX target cities for improved UAQIFS implementation
#1 – Oslo, Norway #2 – Turin, Italy #3 – Helsinki, Finland #4 – Valencia/Castellon, Spain #5 – Bologna, Italy #6 – Copenhagen, Denmark Different ways of the UAQIFS implementation: urban air quality forecasting mode, urban management and planning mode, public health assessment and exposure prediction mode, urban emergency preparedness system.

25 FUMAPEX: Forecast procedure in Oslo
Met.no

26 Erik Bødtker, Danmarks Meteorologiske Institut
11/04/2017 COST 728: Enhancing meso-scale meteorological modelling capabilities for air pollution and dispersion applications ( ) The Action will encourage the advance of the science in terms of parametrisation schemes, integration methodologies/strategies, air pollution and other dispersion applications as well as developing model evaluation methods. In terms of air pollution applications it is recognised that chemical mechanisms and emissions pre-processing are vital components. Four working groups (WG): WG1 Meteorological parameterisation/applications WG2 Integrated systems of MetM and CTM: strategy, interfaces and module unification WG3 Mesoscale models for air pollution and dispersion applications WG4 Development of evaluation tools and methodologies

27 WG2: Integrated systems of MetM and CTM/ADM: strategy, interfaces and module unification
The overall aim of WG2 will be to identify the requirements for the unification of MetM and CTM/ADM modules and to propose recommendations for a European strategy for integrated mesoscale modelling capability. WG2 activities will include: Forecasting models Assessment models

28 Meteorology and Air Pollution: as a joint problem
Meteorology is a main source of uncertainty in APMs => needs for NWP model improvements Complex & combined effects of meteo- and pollution components (e.g., Paris, Summer 2003) Effects of pollutants/aerosols on meteo&climate (precipitation, thunderstorms, etc) Three main stones for Atmospheric Environment modelling: Meteorology / ABL, Chemistry, => Integrated Approach Aerosol/pollutant dynamics (“chemical weather forecasting”) Effects and Feedbacks

29 Why we need to build the European integration strategy?
NWP models are not primarily developed for CTM/ADMs and there is no tradition for strong co-operation between the groups for meso/local-scale the conventional concepts of meso- and urban-scale AQ forecasting need revision along the lines of integration of MetM and CTM US example (The models 3, WRF-Chem) A number of European models … A universal modelling system (like ECMWF in EU or WRF-Chem in US) ??? an open integrated system with fixed architecture (module interface structure) European mesoscale MetM/NWP communities: ECMWF HIRLAM COSMO ALADIN/AROME UM WRF MM5 RAMS European CTM/ADMs: a big number problem oriented not harmonised (??) …..

30 Erik Bødtker, Danmarks Meteorologiske Institut
11/04/2017 ACCENT's goals are to promote a common European strategy for research on atmospheric composition change, to develop and maintain durable means of communication and collaboration within the European scientific community, to facilitate this research and to optimise two-way interaction with policy-makers and the general public. Changes in atmospheric composition directly affect many aspects of life, determining climate, air quality and atmospheric inputs to ecosystems. In turn, these changes affect the fundamental necessities for human existence: human health, food production, ecosystem health and water. Atmospheric composition change research is therefore fundamental for the future orientation of Europe's Sustainable Development strategy.

31

32 Part II: Structure of the urban boundary layer
Vertical structure Horizontal non-homogeneity Temporal variability

33 The atmospheric boundary layer
Lowest layer of the atmosphere Interactions with the earth’s surface are important Diurnal evolution is complicated Turbulence generation by shear and buoyancy is important Fluxes of energy, momentum, and moisture to/from the surface

34 Problems in defining the boundary layer
Complicated vertical structure Sub-layers grow and decay over the diurnal cycle Turbulence is often intermittent, complicating the classification of stability Boundary layer top is not necessarily at inversion

35 The structure of the urban boundary layer - meteorological view
after T. Oke (1988)

36

37 Scales in an Urban Environment

38 Diurnal evolution of the PBL

39 Diurnal evolution of urban BL
day night

40 Boundary layer characteristics
Daytime: Deep mixed layer from surface heating Turbulent eddies on the scale of BL depth Thermally driven flows can develop from spatial variations in surface heating Nighttime: Surface inversion develops from radiational cooling Mixed layer can persist above inversion Turbulence can be intermittent and mix down faster and warmer air

41 Part III: Ways to resolve the UBL structure
1. Obstacles-resolved numerical models - CFD => turbulent closure, bc, geometry, etc. - LES, …, DNS - simple box models 2. Parameterization of sub-grid processes - theoretical - experimental - numerical 3. Downscaling of models / Nesting techniques - NWP-local-scale meteorological models - Mesoscale models – CFD tools - Mesoscale models – Parameterized models

42 Key parameters for urban models of different scales (COST715)

43 One example of the first way (CFD)
Scheme of the building complex and 6 m height horizontal wind field (after Mastryukov et al.)

44 High-resolution mapping of urban areas
CORINE and PELCOM data up to 250 m resolution Land-use database with the resolution 25 x 25 meters (DMU) GIS databases of urban structure (BlomInfo A/S)

45

46 Momentum equations for urban canopy model

47 Two approaches to parameterise the urban canopy effect:
Modifying the existing non-urban (e.g. MOST) approaches for urban areas by finding proper values for the effective roughness lengths, displacement height, and heat fluxes (adding the anthropogenic heat flux, heat storage capacity and albedo change). In this case, the lowest model level is close to the top of the urban canopy (displacement height), and a new analytical model is suggested for the Urban Roughness Sublayer which is a critical region where pollutants are emitted and where people live. Alternatively, source and sink terms are added in the momentum, energy and turbulent kinetic energy equation to take into account the buildings. Different parameterizations (Masson, 2000; Kusaka et al., 2001; Martilli et al., 2002) had been developed to estimate the radiation balance (shading and trapping effect of the buildings), the heat, the momentum and the turbulent fluxes inside the urban canopy, taking into account a simple geometry of buildings and streets (3 surface types: roof, wall and road).

48

49 Wind tunnel data for urban canopy

50 Erik Bødtker, Danmarks Meteorologiske Institut
11/04/2017 Review: theories relating to urban wind profiles (WG1 COS715) Theories will be required for various aspects of the UWF: Roughness sublayer (RS): profile of Reynolds stress & local scaling within RS è wind profile no theory, but good results; parameterisation exists for Reynolds stress profile (to be extended to more data sets) Required: friction velocity of inertial sublayer (IS),    ; z* and d Stability effects? (profile of sensible heat flux? à WG2) Urban canopy (part of RS) Little variation within canopy [height and position] Sharp transition from canopy to above roof region Similar to plant canopies:                           Theory? (Raupach et al., 1996) Possible approach: match the canopy and the RS profiles for 0<z<z* Alternative: sinh formulation (instead of exp): Gayev (??) UBL Urban mixed layer: ‘normal‘ BL scaling regimes and approaches? (e.g. Sorbjan, 1986). Any evidence for this? [à data from Barcelona, LIDAR and RaSo may be used: CS]; effects of sea/topography? Urban stable boundary Layer: see above: UML; data? rural - urban transition: (e.g. information (data) from an airport sampling station, but required knowledge in the city centre) required parameters: scaling velocity / temperature ‘urban‘ and rural. Which level? (see above: RS) theory? (e.g.                         ; Bottema, 1995) Model for ‘surface‘ heat flux: based on Oke’s data, empirical Alternative:       approach for heat flux (based on the notion that this quantity is very much like over rural surfaces even for urban surfaces, see Rotach, 1994) spatial inhomogeneity: city ‘regions‘ internal BL growth [thermal – mechanical]: growth rate ‘as usual‘? à test on Barcelona data city regions (down town, city, residential....): back to IBL?

51 1: Analytical urban parameterisations
Displacement height, Effective roughness and flux aggregation, Effects of stratification on the roughness, Different roughness for momentum, heat, and moisture; Calculation of anthropogenic and storage urban heat fluxes for NWP models; Prognostic MH parameterisations for SBL; Parameterisation of wind and eddy profiles in canopy layer.

52 The effect of stratification of the surface resistance over very rough surfaces S. Zilitinkevich and A. Baklanov (2003) The roughness length depends on the atmospheric temperature stratification. New parameterisations for the effect of stratification on the surface resistance over very rough surfaces are suggested: Stable stratification: Unstable stratification:

53 A simple model of turbulent mixing and wind profile within urban canopy S. Zilitinkevich and A. Baklanov (2004) = the vertical profiles of the velocity: where . the horizontal diffusivity: the vertical eddy diffusivity: = =

54 Erik Bødtker, Danmarks Meteorologiske Institut
11/04/2017 2 (BEP model): Urban effects in the Martilli et al. (2002) parameterization: Roof Wall Street Momentum Turbulence Heat Drag Wake diffusion Radiation

55 BEP Model: parameterization of Martilli et al. (2002)
Horizontal surfaces Street and Roof MOST (Louis formulation) Vertical surfaces Wall Momentum Heat Improvement of the BEP model by Hamdi and Schayes (2004)

56

57 Schematic representation of the numerical grid in the urban module

58 Verification of the BEP model versus the BUBBLE experiment
Vertical profiles of wind velocity (left), friction velocity (middle), and potential temperature (right) measured (points), simulated with MOST (dashed line) and with the urban parameterization of Martilli et al. (2002) (solid line).

59 Characteristics of urban surfaces
Altered albedo – can be higher or lower Higher heat capacity Lower moisture flux to atmosphere Larger roughness elements Increased surface area Source of anthropogenic heat and emissions Impermeable to water Decreased net longwave raditaion loss

60 Part IV: Energy budget in urban areas
The radiation budget does not differ significantly for urban and rural surfaces, as the increased loss of net thermal longwave radiation is partly compensated by a gain in net shortwave radiation due to a lower albedo. The turbulent fluxes of sensible and latent heat, as well as their ratio (β=H/LvE, the Bowen ratio) are variable, depending in particular on the amount of rainfall that fell during the preceding period. However, the impermeability of urban surfaces generally reduces the availability of soil moisture for evaporation after a few rainless days, generally leading to high values of the Bowen ratio. The storage heat flux usually is significantly higher in urban areas compared to densely vegetated surfaces. This cannot be explained entirely by a higher thermal inertia, as this quantity is only slightly higher for urban as compared to rural environments. Other factors of importance are the low moisture availability and the extremely low roughness length for heat fluxes. OHM model (Grimmond et al., 1991). The anthropogenic heat flux is a most typical urban energy component as it is absent over rural or natural surfaces.

61 Energy budget and additional sources of energy need to be considered for cities
Q* = K - K + L - L = QH + LvE + QG + QF the fluxes of heat due to combustion of fuels (QF) by: the traffic, at ground level, the domestic heating, through wall heat transfers and direct release from chimneys, the similar heat releases by small dispersed industries, elevated point sources of warm discharges (high stacks).

62 Variability in Morphology
Implications, across & between cities, for: Wind flow Dispersion Flux partitioning BL height Air quality Surface runoff Solar access Radiative cooling Grimmond & Oke, 1999; JAM

63 Urban Fabric Classification – Method
Database: BD Topo (IGN): Building altitudes Building surfaces Road surfaces Vegetation surfaces Hydrographic surfaces DFMap software Morphology parameters: Average height Volume Perimeter Compactness Space between buildings Cover Modes: Surface density (SD) of buildings SD of vegetation SD of hydrography SD of roads Number of buildings Aerodynamic parameters: Roughness length Displacement height Frontal & lateral SD GIS

64 Erik Bødtker, Danmarks Meteorologiske Institut
Belle Vue S29 Tower Somgande Variability Across a City Erik Bødtker, Danmarks Meteorologiske Institut 11/04/2017 DOWNTOWN .210 (.020) SECTOR 29 .249 (.024) RURAL .276 (.023) 313 (.8) 309 (1.6) 312 (.6) Albedo Surface Temperature (K) Offerle et al. 2004

65 (after Grimmond and Oke, in COST-715, 2001)
Ranges of average daily maximum values of net radiation and fluxes in North American cities (after Grimmond and Oke, in COST-715, 2001) Parameter Range (W m-2) Net all-wave radiation Q* < Latent heat flux LE Sensible heat flux H Storage heat flux G Average daytime Bowen ratios H/LE: Residential sites During irrigation ban Vancouver Light industrial site Downtown (Dimensionless) ~ 2.8 ~ 4.4 ~ 9.8

66 Roughness for momentum, heat, and moisture
The roughnesses are different for urban areas, but they are considered as equal in NWP models. Several possible parameterisations for the scalar roughness length for urban areas can be recommended to improve urban-scale NWP models: 1) Brutsaert (1982) and Brutsaert and Sugita (1996): 2) Hasager et al. (2002): They need to be verified and improved.

67 Urban anthropogenic heat flux

68 Urban anthropogenic heat flux calculation
based on an assumption of dependency/proportionality to other urban characteristics, e.g.: Population density maps with a high resolution in urban areas. Satellite images of the night lightness over urban areas. Difficulties to use for industrial and developing countries (should be corrected). Land-use classification as a percentage of urban classes (central part, urban, sub-urban, industrial, etc.) Emission inventory for specific pollutants, which are typical for urban areas (e.g., due to traffic emission: NOx, …). Monitoring or simulation fields of air pollution concentration for the specific pollutants, which are typical for urban areas (see above #4). Reference values W/m2

69 Module 3: SM2-U model (Mestayer et al., 2003)
Within each cell SM2-U computes the energy budget of each of the 5 cover modes according to their coverage percentage, balancing the net radiation with the heat fluxes, accounting for the transfers to soil layers. The buildings/roofs cover mode receives a special modeling for canopy. The model output is the cell-averaged temperature (plus the heat fluxes). SMU2-U Energy Budget

70 SM2-U WATER BUDGET Within each cell SM2-U computes the water budget of each of the 5 cover modes according to their coverage percentage, balancing precipitation with surface evaporation and vegetation transpiration, accounting for the water transfers between the surfaces and the soil. The model output is the cell-averaged specific humidity (plus vapour and drainage fluxes)

71 From Masson (2000)

72 From Masson (2000)

73 Urban classes presentation in SM2-U for DMI-HIRLAM for the Copenhagen region
SM2-U classes: 1: veg on nat soil, 2: veg on art soil, 3: nat soil veg, 4: art soil veg, 5: bare soil, 6: buildings, 7: water FUMAPEX - SM2 U :106: bat - buildings -1 Magenta 14.60% 0 Yellow 75.86% FUMAPEX - SM2 U : DOMINATING CLASS 1-7 -1 Magenta 14.60%; 1 Green 2.74%; 2 White 0.08%; 3 Black 1.83%; 4 White 0.12%; 5 Yellow 21.79%; 6 Red 2.25%; 7 Blue 56.58%

74 Improved urban surface parameters based on the morphologic methods
Residential District (RD) Industrial Commercial District (ICD) City Center (CC) / High Building District (HBD)

75 Energy budgets over four urban districts (CC: city centre; RD: residential district; ICD: industrial-commercial district; HBD: high building district) simulated by SM2-U for an average diurnal cycle in July (FUMAPEX D4.1, 2004) (—–): net radiation flux; (----): latent heat flux; (–·–·–): sensible heat flux; (–··–··–): storage heat flux

76 SUBMESO CLIMA RUNS FOR COPENHAGEN TEMPERATURE OF THE SURFACE

77 Sensitivity Study on City Representation
SA : Detailed city SB : Homogeneous mean city SC : Mineral city (used in LSM, no buildings, dry bare soil) Mean fluxes (whole urban area) Temperature profiles (above districts) ALL : Different behavior SC vs SA : stores & releases less energy (no radiative trapping) ; Rn is weaker (higher albedo) SA : at 00h neutral stratification above CC & HBD, stable - others. Urban Heat Island is seen (Surface air temperature above the city higher than on the rural area). SC : Stable stratification & temperature homogeneity for all. Importance of urban surface characteristics description

78 Urban heat island

79 Urban effects on air pollution in Mediterranean region

80 Urban BL features for MH estimation
(i) internal urban boundary layer (IBL), (ii) elevated nocturnal inversion layer, (iii) strong horizontal inhomogeneity and temporal non-stationarity, (iv) so-called ‘urban roughness island’, zero-level of urban canopy, and z0u  z0T  z0q, (v) anthropogenic heat fluxes from street to city scale, (vi) downwind ‘urban plume’ and scale of urban effects in space and time, (vii) calm weather situation simulation, (viii) non-local character of urban MH formation, (ix) urban soil, albedo, effect of the water vapour fluxes.


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