IAIN STEWART & TIM OKE
Department of Geography
University of British Columbia
Vancouver CANADA
LOCAL CLIMATE ZONES
Application to heat island studies in tropical regions
Stewart I, Oke T. 2011. Submitted for publication.
LOCAL CLIMATE ZONES
Purpose
• To improve method and consistency in urban heat island studies
• To standardize the description of city and country landscapes for
urban climatologists
Approach
• Divide landscapes into local-scale ‘zones’ based on surface
thermal and structural properties
• Test the ‘zones’ for thermal climate differences using observational
and numerical modeling data
Application
• Site classification, instrument siting, heat island assessment,
urban terrain and climate mapping, settlement planning, climate
modeling, weather forecasting, historical temperature analysis…
LOCAL CLIMATE ZONES (LCZ)
Observational support for LCZs
Evening traverses in Vancouver, 2010
Summary
• UHI datasets from
Sweden (1948, 1976),
Japan (2000-06), and
Canada (1992-2010).
• Observations support the
divisional structure of the
LCZ system.
• Each LCZ class has a
unique thermal climate.
• Temperature patterns are
sensitive to surface relief,
surface wetness, tree
geometry, and weather.
Departure from traverse mean (K)
Stewart I, Oke T. 2010. Preprints, 9th Symposium on Urban Environment.
Summary S. Krayenhoff
University of British Columbia
• Highly simplified approach
(trees excluded).
• Urban-surface (TEB) and
plant-soil (CAPS) schemes
coupled with atmospheric
boundary layer model.
• Daily temperature range
(DTR) varies with building
height & packing, land
cover, and surface wetness.
• Natural zones more
thermally responsive than
built-up zones.
Numerical modeling support for LCZs
See Krayenhoff et al., 2009. Preprints, 8th Symposium on the Urban Environment.
-6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10
Departure from the group mean DTR (K)
Compact highrise
Open lowrise
Sparsely built
Large lowrise
Lightweight lowrise
Compact midrise
Open midrise
Heavy industry
Bare so il or sand
Low plants
Departure from group mean DTR (K)
1. Source areas (wind, surface geometry, boundary layer stability)
2. Zone combinations (mixed landscapes, ephemeral landscapes)
Sao Paulo, BRAZIL
HONG KONG
Tainan, TAIWAN
LCZs and the tropical environment
DEFINITION
Form: Dense and irregular mix of tall buildings to 10s of stories. Buildings close-set, free-standing. Sky
view from street level significantly reduced. Streets paved. Buildings of steel, concrete, and glass
construction. Little or no pervious ground. High space heating/cooling demand. Heavy traffic flow.
Function: Commercial (office buildings, highrise hotels); residential (apartment towers). Location: City
core (“downtown,” central business district). Periphery (highrise subcentre, highrise sprawl).
Correspondence: UCZ1 (Oke, 2004); Dc1 and Dc8 (Ellefsen, 1990/1).
ILLUSTRATION
Sky view factor 0.2 – 0.4 0 .2 .4 .6 .8 1
Canyon aspect ratio > 2 .20 .4 .6 .8 1 2 3 Mean building height > 35 m 0 10 20 30 40 50
Terrain roughness class 8 87654321
Building surface fraction 40 – 60 % 0 20 40 60 80 100
Impervious surface fraction 40 – 60 % 0 20 40 60 80 100 Pervious surface fraction < 10 % 0 20 40 60 80 100
Surface thermal admittance 1,100 – 1,800 J m-2 s1/2 K-1 0 500 1,000 1,500 2,000 2,500
Surface albedo 0.10 – 0.20 0 0.1 0.2 0.3 0.4 0.5
Anthropogenic heat flux 50 – 300 W m-2 0 100 200 300 400
LCZ COMPACT HIGHRISE 1
High angle
Eye level
PROPERTIES
LCZ 1 in Kuala Lumpur: bird’s eye view
LCZ 1 in Hong Kong: street view
LCZs and the tropical environment
3. Zone communication (datasheets)
Examples of LCZ application
Santiago, CHILE
Assessing social
inequalities
Nagpur, INDIA
Mapping urban
terrain
Barranquilla,
COLOMBIA
Classifying
built form
Onitsha, NIGERIA
Quantifying UHI
magnitude Mid-latitude city
Low latitude city
Investigators
• R. Kotharkar, M. Surawar, VNIT
(Nagpur)
Nagpur INDIA 21°N Mapping Urban Terrain
Purpose
• To produce an LCZ map for the
city of Nagpur, and to monitor LCZ
temperatures using stationary and
mobile measurements.
• To develop a spatial database of
urban form, function, and
temperature distribution, and to
propose a suitable use for that
database in local urban planning.
Kotharkar R. 2011. Pers. comm.
1
5
3
2 4
LCZ 2: Compact midrise LCZ 5: Open midrise
LCZ 9: Sparsely built LCZ 7: Lightweight lowrise
Purpose
• To acquire standardized
information on built form in
Barranquilla, using the LCZ
framework.
Investigator
• K. Villadiego, Universidad de
Paul Cézanne (Marseille)
Preliminary findings
• Eight different LCZs are
represented in Barranquilla.
• Land use and land cover are
highly mixed in Barranquilla;
classification into LCZs requires
use of zone combinations.
Barranquilla COLOMBIA 10°N Classifying Built Form
Sud Occidente LCZ 3 Compact lowrise
Miramar LCZ 5 Open midrise
San Roque LCZ 2 Compact midrise
Alto Prado LCZ 1 Compact highrise
Villadiego K. 2011. Pers. comm.
Onitsha NIGERIA 6°N Quantifying UHI Magnitude
Investigator
• I.C. Nduka, Ahmadu Bello University
(Onitsha)
Findings
• Largest UHI magnitudes observed in
old core (LCZ 2); smallest magnitudes
in shantytown (LCZ 7).
• Impervious surface fractions of LCZs
in Onitsha are lower than midlatitude
cities; LCZ classes must be adaptable
to developing cities.
Purpose
• To quantify UHI magnitude through
inter-zone temperature differences
(DTLCZ).
LCZ 2: Compact midrise
Nduka IC. 2011. Research Journal of Environmental and Earth Sciences.
LCZ 7: Lightweight lowrise
Santiago CHILE 33°S Assessing Social Inequalities
Purpose
• To map LCZs in Santiago, observe
thermal differences among LCZs, and
relate these differences to socio-
economic status of district populations.
Investigators
• H. Romero et al., Universidad de Chile
(Santiago)
Findings
• LCZ morphology reflects thermal and
social inequalities in Santiago.
• High-density districts: high temperatures,
high heat stress, low-income populations.
• Low-density districts: low temperatures,
low heat stress, affluent populations.
Romero H. et al. 2010. Revista INVI .
• A simple user-friendly classification that does not require
significant resources or sophisticated technology
• A flexible classification that adapts easily to hot, humid,
and dry environments
• A standardized definition of UHI magnitude (DTLCZ ) that
enables valid comparisons with midlatitude cities
• An educational tool for disseminating basic urban climate
information
• A practical tool for linking urban design elements with
thermal climate
FINAL REMARKS
What does the LCZ system offer to tropical urban climatology?