WP2: Megacity Environments: Features, Processes and Effects

 
Coordinated by S. Grimmond (KCL) and I. Esau (NERSC)

 

MEGAPOLI Partners involved: DMI, AUTH, FMI, JRC, KCL, NERSC, NILU, UHam, UHel

Summary of progress toward objectives

Following O2.1 (To develop morphology/land-use/land-cover classifications and databases for megacities to be used in meteorological, air quality and population exposure modelling) - a prototype of an urban morphological database has been developed (Sievinen et al., 2009) and made available for the project participants. The database relies on digital maps and satellite observations including optical images, SAR interferometry, and digital maps. A fine resolution model was compiled regarding urban morphological features that cover a rectangular area of 6 x 3 km2 in central Paris. The model contains selected thematic layer types on water, parks, trees, streets, buildings, average height of blocks, digital elevation model of the terrain, coherence and the urban heat fluxes.
Following O2.2 (To develop sub-grid parameterisations of urban layer processes for megacity, regional and global scale models) - the work proceeds with different approaches to include urban canopy effects, dispersion, and large-scale turbulence self-organization and stability effects on air flow. Urban canopy effects are aggregated in simple parameters, primarily urban roughness. Aggregation and transport of dispersion is studied with CFD, LES, and Enviro-HIRLAM models. Different approaches are tried to account for the small-scale, unresolved fluxes.

Summary details for each relevant WP deliverables, milestones, and tasks 

Task 2.1: Surface morphology: classification and database (lead: FMI)
First version of a surface morphology database on Paris has been completed and released by Helsinki University of Technology and FMI. An area of 6 x 3 km2 around Place d’Italie has been surveyed in detail. The database contains selected thematic layers on water, parks, trees, streets, buildings, average height of blocks, digital elevation model of the terrain, coherence, and the surface heat flux. A larger area, covering the interior of the beltway around Paris, has been surveyed with lesser detail and lower resolution.

Task 2.2: Flow deformation by urban canopy in the urban sub-layer (lead: DMI, UHel),
We are working with 3 different approaches to include urban canopy effects on air flow (see: http://www.atmos-chem-phys.net/8/523/2008/acp-8-523-2008.pdf). Urban canopy effects are aggregated in simple parameters, primarily urban roughness. We obtained the maps of the urban roughness and displacement height over Paris aggregated using an objective least-square minimization of the 10 m resolution LES data from Task 2.4. More studies have been done with LESNIC code including experiments with an artificial neural network in a posteriori mode. We identified the urban canopy (buildings) as the surface feature which modifies the momentum flux in the turbulent log-layer flow. For the roughness (single-layer) approach the new parameterization with stability dependences was suggested and tested (Zilitinkevich et al., 2008). Other approach is based on the source/sink terms (Martilli et al., 2002) and realized in the BEP module. The CFD obstacle-resolved model M2UE is used for evaluation of the urban canopy parameterizations of drag, dispersive stress and dispersive fluxes. Multi-scale interaction aspects have been also analyzed. Enviro-HIRLAM was running for the Paris summer 2009 campaign. RSHU is also running the Enviro-HIRLAM with a simple urbanization module considering anthropogenic heat flux, roughness, and albedo influence for the St-Petersburg megacity effects study.

Task 2.3: Urban energy balance (lead: KCL, UHam)
Comparison of urban energy balance models off-line has been conducted with two datasets. Just under 30 different models are participating. Initial analysis has been conducted for the first data set and a paper submitted (Grimmond et al. 2009, JAMC submitted). For the second data set a conference presentation and preprint have been prepared (Grimmond et al. 2009, ICUC7, & 2 invited talks). This work has resulted in the development of a model classification scheme (Grimmond et al. 2009, JAMC submitted). This is now being used as a basis for evaluating the model performance (Grimmond et al. 2009, JAMC, ICUC7). The comparative study of the combined effects of urban features and air pollution (aerosols) from megacities on meteorology and environment at different scales using online coupled Enviro-HIRLAM model with 2-way feedbacks on the example of Paris was completed in DMI.

Task 2.4: Urban atmospheric boundary layer (UABL) (lead: NERSC, AUTH)
Using the surface morphology database from Task 2.1, turbulence-resolving simulations with the urbanized code PALM were conducted on a set of meshes with resolution from 1 m to 50 m. The primary experiment was run on the 50 m mesh for the entire central Paris area (12 km by 10 km). It was demonstrated that the buildings (urban canopy) considerably modify the vertical mixing properties in the turbulent flow even in the case of the large elevation differences of the unlaying terrain. We found, and it is now confirmed with 4 independent LES codes, that the turbulence is organized in the sheared flow with the maximum organization found for easterlies. The mere self-organization (and therefore wind direction) may change the mixing in the planetary boundary layer (PBL) by factor of 2 with increasing effect over more rough surfaces. The climatologic impact of the PBL is discussed in Zilitinkevich and Esau (2009). The obtained LES data were used to constrain the urban parameterizations in large scale meteorological models. We confirmed the empirical relationship on the dependence between the mean building height and the parameters of the surface layer parameterization. The maps of the aggregated parameters for the Paris were computed. We continue to improve urbanization of the LES codes. A more flexible and accurate method (the Breugem–Boersma immersed boundary stress method) is now under implementation.

Task 2.5: Megacity dispersion features (lead: JRC, AUTH, NILU)
NERSC is solving the problem of data assimilation on turbulence scales. This is the problem of the turbulent fields’ recovery using the mean (observed) values of the meteorological parameters. The assimilation nudging routine is ready. Results of the relevant MUST wind tunnel experiment for dispersion of air pollution from fixed releases in idealized urban roughness set ups are analyzed by DMI and AUTH. LHTEE’s RANS CFD code for urban dispersion problems, MIMO, were run for two small areas of 500 x 500 m in the city of Athens (the shore of Piraeus and Patision and Fokionos Negri streets in downtown Athens), within the frame of the joint project with the Toyhashi University in Japan, MEMICO, as MEsocale – MIcroscale - COupling.

Deliverable 2.1 - Morphology database for a target megacity
is ready and available from the MEGAPOLI public website. Pauli Sievinen, Antti Hellsten, Jaan Praks, Jarkko Koskinen, Jaakko Kukkonen (2010): Urban Morphological Database for Paris, France. Deliverable D2.1, MEGAPOLI Scientific Report 10-02, MEGAPOLI-05-REP-2010-03, 13p., http://megapoli.dmi.dk/publ/MEGAPOLI_sr10-02.pdf

Deliverable 2.2 - Hierarchy of urban canopy parameterisations for different scale
is ready and available from the MEGAPOLI public website. Mahura A., Baklanov A. (Eds.) (2010): Hierarchy of Urban Canopy Parameterisations for Different Scale Models. Deliverable D2.2, MEGAPOLI Scientific Report 10-04, MEGAPOLI-07-REP-2010-03, 50p., http://megapoli.dmi.dk/publ/MEGAPOLI_sr10-04.pdf
 
Deliverable 2.3 - Evaluation of surface flux balance modelling and urban features needed for climate and air quality models
is ready and available from the MEGAPOLI public website. Grimmond CSB., M. Blackett, M.J. Best, et al. (2010): Urban Energy Balance Models Comparison. Deliverable D2.3, MEGAPOLI Scientific Report 10-07, MEGAPOLI-10-REP-2010-03, 72p., http://megapoli.dmi.dk/publ/MEGAPOLI_sr10-07.pdf

Deliverable 2.4.1 - Urbanized turbulence-resolving model and evaluation against WP3 Paris plume data
is ready and available from the MEGAPOLI public website. Igor Esau (2010): Urbanized turbulence-resolving model and evaluation against WP3 Paris plume data. Deliverable D2.4.1, MEGAPOLI Scientific Report 10-06, MEGAPOLI-09-REP-2010-03, 20p., http://megapoli.dmi.dk/publ/MEGAPOLI_sr10-06.pdf

Deliverable 2.4.2 - Urbanized turbulence-resolving model and evaluation against WP3 Paris plume data
is ready and available from the MEGAPOLI public website. Esau I. (2011): Urbanized turbulence-resolving model and evaluation against WP3 Paris plume data. Deliverable D2.4.2. MEGAPOLI Scientific Report 11-15, MEGAPOLI-41-REP-2011-09, 49p., http://megapoli.dmi.dk/publ/MEGAPOLI_sr11-15.pdf

Deliverable 2.5 - mproved Urban Parameterizations Based on Prognostic Equations, Utilizing LES Results
is ready and available from the MEGAPOLI public website. Esau I., Baklanov A., Zilitinkevich S. (2011): Improved Urban Parameterizations Based on Prognostic Equations, Utilizing LES Results. Deliverable D2.5 MEGAPOLI Scientific Report 11-14, MEGAPOLI-40-REP-2011-09, 61p, http://megapoli.dmi.dk/publ/MEGAPOLI_sr11-14.pdf

Deliverable 2.6 - Evaluation of Sub-Grid Models with Interactions between Turbulence and Urban Chemistry. Recommendations for Emission Inventories Improvement
is ready and available from the MEGAPOLI public website. Galmarini S., Vinuesa J.F., Cassiani M., Denby B., Martilli A., (2011): Evaluation of Sub-Grid Models with Interactions between Turbulence and Urban Chemistry. Recommendations for Emission Inventories Improvement. Deliverable D2.6, MEGAPOLI Scientific Report 11-01, MEGAPOLI-27-REP-2011-01, 41p., http://megapoli.dmi.dk/publ/MEGAPOLI_sr11-01.pdf

Deliverable 2.7 - Improved Parameterization of Dispersion due to Subgrid Heterogeneities in Emission for Different Scale Models
is ready and available from the MEGAPOLI public website. Galmarini S., J.F. Vinuesa, M. Cassiani (2011): Improved Parameterization of Dispersion due to Subgrid Heterogeneities in Emission for Different Scale Models. Deliverable D2.7, MEGAPOLI Scientific Report 11-19, MEGAPOLI-45-REP-2011-09, 16p, http://megapoli.dmi.dk/publ/MEGAPOLI_sr11-19.pdf

Significant results: Methodologies and scientific achievements related to WP including partners' contributions

FMI contributed the morphology database for central Paris. NERSC contributed with urbanization of PALM and LESNIC LES models. This database has been used to run turbulence-resolving LES experiments and to obtain the urban boundary layer properties on 10 m to 50 m resolution. The LES data have been aggregated on coarser, meteorological mesh of O(1 km) resolution to map the parameters for UBL closures specific for the Paris area. UHel and FMI formulated the total turbulence energy theory as the foundation for the improved roughness and urban effects parameterizations. LHTEE completed studies with CFD code for segments of Athens. NERSC demonstrated feasibility of the data assimilation in the LES models over partially unresolved urban canopy. To further quantify the effect of resolution, a set of LES runs with resolutions from 1 m to 100 m have been computed. KCL organized intercomparison study for the urban canopy schemes. DMI tried the new development nesting in the micro- to meso-scale model Enviro-HIRLAM+M2UE.

 

Discussion and conclusion
The 1st version of the morphology database has been released. It makes possible to go from idealized case studies to the realistic simulations for the top megacity in the project – Paris. The main focus is now on feasibility studies, aggregation methods and calibration of the proposed parameterizations and approaches to deal with (i) urban canopy, (ii) urban effects and (iii) micro-climate impact of the urban boundary layer modification. The completed intercomparison of the urban schemes will provide frameworks to judge the development. The simpler (delta) and more complicated (pdf) approaches to the dispersion problem are to be tried and validated against LES. 

 

List of WP2 reports, publications, presentations

Publications:

Baklanov A, J Ching, CSB Grimmond, A Martilli, (2009),  Summaries of Discussions, Recommendations and Requirements Urbanization of Meteorological and Air Quality Models,  (eds) Baklanov A, S Grimmond, A Mahura M Athanassiadou Springer-Verlag, ISBN: 978-3-642-00297-7, 151-162

Baklanov A., P. Mestayer, A. Clappier, S. Zilitinkevich, S. Joffre, A. Mahura, N.W. Nielsen, (2008), Towards improving the simulation of meteorological fields in urban areas through updated/advanced surface fluxes description, Atmospheric Chemistry and Physics, vol. 8, pp. 523-543

Baklanov A. A. and R. B. Nuterman (2009): Multi-scale atmospheric environment modelling for urban areas. Adv. Sci. Res., 3, 53-57.

Baklanov, A., S. Grimmond, A. Mahura, M. Athanassiadou, 2009: Meteorological and Air Quality Models for Urban Areas. Springer, 2009, 140 p.

Cassiani, M., J. F. Vinuesa, S. Galmarini, and B. Denby, (2009), Stochastic fields method for sub-grid scale emission heterogeneity in mesoscale atmospheric dispersion models, Atmos. Chem. Phys. Discuss., 9, 15215-15245

Esau, I. (2009): Numerical experiments with assimilation of the mean and unresolved meteorological conditions into large-eddy simulation model, submitted to Advances in Meteorology

Esau, I. (2009): Large-eddy simulations of geophysical turbulent flows with applications to planetary boundary layer research, arXiv:0907.0103v1

Esau, I., (2009): Large-eddy simulation experiments with nudging to observed mean meteorological profiles, MEGAPOLI Newsletters, n3, p.9, MEGAPOLI-NL03-09-06.

Esau, I., (2009): The question of scale: Large Eddy Simulation in urban research, MEGAPOLI Newsletters, n3, p.7, MEGAPOLI-NL03-09-06.

Gavrilova Yu., A. Mahura, S. Smyshlayev, A. Baklanov (2009): Thermal and Dynamical Urban Effects of Saint-Petersburg Metropolitan Area – Winter Case Study. Abstracts of the International Conference on Computational Information Technologies for Environmental Sciences: CITES-2009, 11-15 Jul 2009, Krasnoyarsk, Russia, pp. 63-64.

Gavrilova Yu., A. Mahura, S. Smyshlayev, A. Baklanov (2009): Thermal and Dynamical Urban Effects of Saint-Petersburg Metropolitan Area. MEGAPOLI Newsletters, n4, p.5, MEGAPOLI-NL04-09-09.

Grimmond CSB, M Best, J Barlow and AJ Arnfield J-J Baik, S Belcher, M Bruse, I Calmet, F Chen, P Clark, A Dandou, E Erell, K Fortuniak, R Hamdi, M Kanda, T Kawai, H Kondo, S Krayenhoff, SH Lee, S-B Limor, A Martilli, V Masson, S Miao, G Mills, R Moriwaki, K Oleson, A Porson, U Sievers, M Tombrou, J Voogt, T Williamson, (2009), Urban surface energy balance models: model characteristics and methodology for a comparison study Urbanization of Meteorological and Air Quality Models, (eds) Baklanov A, CSB Grimmond, A Mahura, M Athanassiadou Springer-Verlag, ISBN: 978-3-642-00297-7, 97-123.

Grimmond CSB, M Blackett, M Best, J Barlow, JJ Baik, S Belcher, SI Bohnenstengel, I Calmet, F Chen, A Dandou, K Fortuniak, ML Gouvea, R Hamdi, M Hendry, H Kondo, S Krayenhoff, SH Lee, T Loridan, A Martilli, V Masson, S Miao, K Oleson, G Pigeon, A Porson, F Salamanca, L Shashua-Bar, GJ Steeneveld, M Tombrou, J Voogt, N Zhang (2009) The International Urban Energy Balance Models Comparison Project: First results from Phase 1 Journal of Applied Meteorology and Climatology (submitted)

Hidalgo, J., V. Masson, A. Baklanov, G. Pigeon, and L. Gimeno. Advances in Urban Climate Modeling. Trends and Directions in Climate Research: Ann. N.Y. Acad. Sci. 1146: 354?374 (2008). doi: 10.1196/annals.1446.015

Mahura A., C. Petersen, A. Baklanov, B. Amstrup, U. S. Korsholm, K. Sattler, (2008), Verification of longterm DMI-HIRLAM NWP model runs using urbanisation and builing effect parameterization modules, HIRLAM Newsletter, vol. no.53, no. 11pp,

Mahura A., Leroyer S., Baklanov A., Mestayer P., Korsholm U.S., Calmet I., (2009): Temporal and Spatial Variability of Fluxes in Urbanized Areas, pp-219-232; In “Urban Climate and Bioclimate”, (Eds. Klysik K., Wibig J., Fortuniak K.), ISBN: 978-83-7525-243-9.

Mahura A., Petersen C., Baklanov A., Amstrup B., (2009): Evaluation of Building Effect Parameterization Module for Urbanized Numerical Weather Prediction Modelling, pp-371-380; In “Urban Climate and Bioclimate”, (Eds. Klysik K., Wibig J., Fortuniak K.), ISBN: 978-83-7525-243-9.

Mahura A., Baklanov A., Petersen C., N. W. Nielsen, B. Amstrup (2009): Verification and Case Studies for Urban effects in HIRLAM Numerical Weather Prediction, pp. 143-150. In “Urbanization of Meteorological and Air Quality Models”, (Eds. Baklanov A., S. Grimmond, A. Mahura, M. Athanassiadou), ISBN: 978-3-642-00297-7.

Mahura A., Baklanov A., Hoe S., J.H. Sorensen, C. Petersen (2009): Changes in Meteorological and Atmospheric Transport and Deposition Patterns due to Influence of Metropolitan Areas. Ukrainian Hydrometeorological Journal, Vol. 4, pp. 187-194.

Mahura A., S. Leroyer, P. Mestayer, A. Baklanov, C. Petersen (2009): Urbanization in Atmospheric Modelling with High Spatial and Temporal Resolution. Abstracts of the International Conference on Computational Information Technologies for Environmental Sciences: CITES-2009, 11-15 Jul 2009, Krasnoyarsk, Russia, pp. 64-65.

Nuterman R.B., Starchenko A.V., Baklanov A.A., (2007), Development and analysis of microscale meteorological model for airflow investigation in urban canopy. J. of Computational Technologies, Vol. 13, Special issue 3, P. 37-43.

Nuterman R., Starchenko A., Baklanov A., (2010), Numerical model of urban aerodynamics and pollution dispersion. Accepted for publication in Int. J. of Environment and Pollution, 8 p.

Nuterman, A.A. Baklanov, A.V. Starchenko, (2009). Application of Microscale model for development of urban canopy parametrization scheme for mesoscale models. Ukrainian Hydro-meteorological Journal, No.4, P. 6 (In Press).

Nuterman R. (2008) Modelling of turbulent flows and pollution transport in urban canopy. PhD thesis, 156 p.

Zilitinkevich, S.S., I. Mammarella, A.A. Baklanov, S.M. Joffre (2008): The Effect of Stratification on the Aerodynamic Roughness Length and Displacement Height. Boundary-Layer Meteor, 129: 179-190. DOI:10.1007/s10546-008-9307-9.

Zilitinkevich, S.S., T. Elperin, N. Kleeorin, I. Rogachevskii and I. Esau, (2009): An energetically balanced turbulence closure for stably and very stably stratified flows Symposium on Multiphase Flow in Atmospheric Boundary Layer: Wind Erosion, Dust Storms, Sand Saltation, Snow Drift, Lanzhou, China, October 16-18

Zilitinkevich, S.S., and Esau, I., (2009): Planetary boundary layer feedbacks in climate system and triggering global warming in the night, in winter and at high latitudes, submitted in Geography, Environment and Sustainability

 

Presentations:

Blackett M, ML Gouvea, T Loridan, S Grimmond, (2009), Modelling Urban Surface-Atmosphere Interactions Sustainable Urban Planning in London Meeting of the Bridge researchers and London experts, Community of Practice (CoP), London, August 24, 2009 (poster)

Esau, I., (2009): Large-eddy simulation experiments with nudging to observed mean meteorological profiles, EGU General Assembly, 19-24 April, Vienna, Geophysical Research Abstracts,11, EGU2009-1501

Esau, I., (2009): Physical mechanism and quantitative assessment of the planetary boundary layer feedback in the climate system, The IARU International Scientific Congress on Climate Change, March 10-12, Copenhagen, DK

Grimmond CSB, M Blackett, M Best, JJ Baik, S Belcher, SI Bohnenstengel, I Calmet, F Chen, A Dandou, K Fortuniak, M Gouvea, R Hamdi, M Hendry, H Kondo, S Krayenhoff, SH Lee, T Loridan, A Martilli, V Masson, S Miao, K Oleson, G Pigeon, A Porson, F Salamanca, GJ Steeneveld, M Tombrou, J Voogt, N Zhang (2009), The International Urban Energy Balance Comparison Project: Initial Results from Phase 2, ICUC7 Yokohama, Japan, June 29- July 3, 2009 (A11-6, preprint)

Grimmond CSB, (2009) Urban surface atmosphere exchanges: Measurements and modelling, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Japan, 21 July 2009 (invited)

Grimmond CSB (2009) Urban surface-atmosphere exchanges: results from modelling and measurements, Institute of Industrial Science, The U Tokyo, Japan, 17 July 2009 (invited)

Grimmond S, Blackett M, M Best,  and the IUEBC team, (2009), First results from the International Urban Energy Balance Model Comparison: Model Complexity, EGU Vienna, Austria 19-24 April 2009 (poster)

Grimmond S, M Blackett, M Best, with Baik J, Bohnenstengel S, Calmet I, Chemel C, Chen F, Dandou A, Fortuniak K, Gouvea M, Hamdi R, Kondo H, Krayenhoff S, Lee S, Loridan T, Martilli A, Masson V, Miao S, Oleson K, Pigeon G, Porson A, Salamanca F, Shashua-Bar L, Steeveveld G, Sugar L, Trombou M, Voogt J, Zhang N, (2009), Model Complexity: First results from the international urban surface energy balance model comparison study AMS 89th Annual Meeting/ Eighth Symposium on the Urban Environment, 11–15 January 2009, Phoenix, USA

Grimmond S, M Blackett, M Best, with Baik J, Bohnenstengel S, Calmet I, Chemel C, Chen F, Dandou A, Fortuniak K, Gouvea M, Hamdi R, Kondo H, Krayenhoff S, Lee S, Loridan T, Martilli A, Masson V, Miao S, Oleson K, Pigeon G, Porson A, Salamanca F, Shashua-Bar L, Steeveveld G, Sugar L, Trombou M, Voogt J, Zhang N, (2009), An international urban surface energy balance model comparison study: first results, AMS 89th Annual Meeting/ Eighth Symposium on the Urban Environment, 11–15 January 2009, Phoenix, USA

Lawrence M, A Baklanov, S. Pandis , and the MEGAPOLI team, (2009), Megacity Pollution Effects from Urban to Global Scales: Overview of the new EC 7FP Project “MEGAPOLI, EGU Vienna, Austria 19-24 April 2009. (invited)

Sievinen P., Praks J., Hallikainen M., Koskinen J., Hellsten A., Kukkonen J. (2009), Urban morphology retrieval by means of remote sensing for the modelling of atmospheric dispersion and micro-meteorology, proceedings of the 2009 IEEE International Geoscience & Remote Sensing Symposium (IGARSS 2009), Cape Town, South Africa, July 12th - 17th.

Zilitinkevich, S.S., and I. Esau, (2009): Atmospheric planetary boundary layer feedback in climate system and triggering of climate change at high latitudes EGU General Assembly, 19-24 April, Vienna, Geophysical Research Abstracts,11, EGU2009-1496

Zilitinkevich, S.S., T. Elperin, N. Kleeorin, I. Rogachevskii, I. Esau, T. Mauritsen, M. W. Miles, (2008): Turbulence energetics in stably stratified geophysical flows: strong and weak mixing regimes, preprint available from arXiv

Zilitinkevich, S., Esau, I., (2008): Atmospheric planetary boundary layer feedback in climate system and triggering of climate change at high latitudes, 8th EMS Annual Meeting and 7th European Conference on Applied Climatology (ECAC), 29 September – 03 October, Amsterdam, The Netherlands


FP7 EC MEGAPOLI, 2008-2011