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?