Institute forAtmospheric and EarthSystem Research
URBAN METEOROLOGYAND THE IMPACT OFURBAN PLANNING
5.11.2019Urban meteorology 1
Leena JärviUniversity of Helsinki
4 November 20192nd Conference of Nordic Network for
Diversity in Physics
Institute forAtmospheric and EarthSystem Research
CONTENT• What is urban meteorology?• How the interaction between
urban surface and atmospherecan be measured?
• Computational fluid dynamics tobe used in urban meteorologyresearch
• Examples on how urbanmeteorology research can supporturban planning
5.11.2019Urban meteorology 2
Oke et al. (2017)
Institute forAtmospheric and EarthSystem Research
WHAT IS URBANMETEOROLOGY?
• Urban area is in constant interaction with the atmosphere• This interaction depends on urban form and function
which is directly connected to urban metabolism (i.e. flowsand transformation of materials and energy in a city)
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Oke et al. (2017)
Urban metabolism
Institute forAtmospheric and EarthSystem Research
EXAMPLES ON THE EFFECTOF URBAN SURFACE ONATMOSPHERE
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Urban form Urban functionFriction to the air flow Emissions of greenhouse gas emissions
(CO2 the most important)Decreased evaporation Air pollutant emissions (gases, aerosol
particles)Increased heat emissions Increased heat emissions
Institute forAtmospheric and EarthSystem Research 5.11.2019 5
DIRECT MEASUREMENTS OFINTERACTIONS IN HELSINKI
Kumpula since 2005
AJ Kieloaho
P. Karsisto
Karsisto et al. (2015)
City centre since 2010
Sens
ible
heat
flux
(Wm
-2)
Jan – Feb 2017
CO
2flu
x(u
mol
m-2
s-1)
Time
City centreKumpula
Urban meteorology
• Micrometeorological measurement of energy,mass and momentum carried out byturbulence (i.e. flux per area per time unit)
Institute forAtmospheric and EarthSystem Research
DIRECT INFORMATION ONPEOPLE’S ACTIVITY
Time
Car
bon
diox
ide
flux
(um
olm
-2s-1
) Cars and people gatherin Helsinki city centre
Celebrations ofFinland winning theice hockey worldchampionship in citycentre in 15.-16.5.2011
5.11.2019Urban meteorology 6
Institute forAtmospheric and EarthSystem Research
SPATIAL LOCAL-SCALE CO2EMISSIONS IN HELSINKI IN 2012
- Emissions: Traffic, human metabolism, domestic energyuse, soil & vegetation respiration
- Sinks: vegetation uptake- Data from open databases- For population, mobility from/to each 250 m x 250 m
grid (Digital Geography Lab, UHEL)
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Nordbo et al. 2015)
Traffic
Land use Traffic
Night-time population Daytime population
Järvi et al. 2019
Institute forAtmospheric and EarthSystem Research
RADIATION, HEAT EMISSIONSAND URBAN FORM DETERMINEFORMATION OF URBAN HEATISLAND
5.11.2019Urban meteorology 8
2 m air temperature in 2012
Surface temperature on June 2017 (2 h)
By Jani Strömberg
Institute forAtmospheric and EarthSystem Research
COMPUTATIONAL FLUIDDYNAMICS USED INURBAN MET RESEARCH
• Large eddy simulation (LES) can solve 3D flow above urbanlandscapes
• LES model PALM model (Maronga et al. 2019) particularlydesigned for urban areasØ < 1 m spatial resolutionØ ParallelizedØ Nesting capabilityØ Permeable vegetationØ Aerosol dynamics
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By Mikko Auvinen
Institute forAtmospheric and EarthSystem Research
TURBULENT KINETICENERGY IN CENTRALHELSINKI
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By Mikko Auvinen
Meteorology (i.e flow) + emissions + aerosol processesdetermine the local air pollutant concentrations!
Institute forAtmospheric and EarthSystem Research
HOW DIFFERENT BUILDINGBLOCK LAYOUTS MODIFYLOCAL POLLUTANTCONCENTRATIONS?
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WindPollutantconcentration
Improvement up to 10%
Kurppa et al. 2018
Institute forAtmospheric and EarthSystem Research
GOOD – BAD URBANVEGETATION
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S0 S1
S2A S2B
S2C S3
Parallel wind Perpendicular wind
By Sasu Karttunen
Institute forAtmospheric and EarthSystem Research
AERODYNAMIC EFFECTGREATER THAN DRYDEPOSITION
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S2A
S0
By Sasu Karttunen
Institute forAtmospheric and EarthSystem Research
CONCLUSIONS• Urban meteorology results from the interaction between
urban surface and the atmosphere• Increased pollutant and GHG emissions• Interaction can be measured using micrometeorological
techniques• We get information on people’s movements• CFD modelling can resolve many of the urban specific
atmospheric features• Can be used in urban planning
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Institute forAtmospheric and EarthSystem Research
THANK YOU!HTTPS://WWW.HELSINKI.FI/EN/RESEARCHGROUPS/URBAN-METEOROLOGY
Järvi L. et al. (2019). Spatial modelling of local-scale biogenic and anthropogenic carbon dioxide emissionsin Helsinki. Journal of Geophysical Research – Atmospheres 124, doi: 10.1029/2018JD029576.Kurppa M. et al. (2018). Ventilation and Air Quality in City Blocks Using Large Eddy Simulation - UrbanPlanning Perspective Atmosphere 9 (2), 65.Lindberg F., et al. (2017). Urban Multi-scale Environmental Predictor (UMEP): An integrated tool for city-based climate services. Environment Modelling and Software 99, 70-87.Nordbo A. et al. (2015). Urban surface cover determined with airborne lidar at 2 m resolution - implicationsfor surface energy balance modelling. Urban Climate 13, 52-72, doi: 10.1016/j.uclim.2015.05.004.Oke T.R et al. (2017). Urban Climates, Cambridge University Press
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