Luca Rozália Száraz: The Impact of Urban Green Spaces on Climate and Air Quality in Cities

LUCA ROZÁLIA SZÁRAZ
BSc, Expert in Applied Environmental Studies
Human ecology masters student at Eötvös Loránd Universty
Environmental researcher at the Metropolitan Research Institute, Budapest
szaraz.luca@gmail.com
<strong>The</strong> <strong>Impact</strong> <strong>of</strong> <strong>Urban</strong> <strong>Green</strong> <strong>Spaces</strong> on Climate
and Air Quality in Cities
Abstract
Every urban landscape is significantly different from any other environment.
<strong>The</strong>se urban landscapes having green spaces decreased are mainly made <strong>of</strong>
artificial surfaces which have unique physical attributes unlike any other landscape
surface. <strong>The</strong> combination <strong>of</strong> dominant artificial surfaces and decreased
vegetation creates an urban climate which influences the air quality, outdoor
thermal and human comfort. Although, half <strong>of</strong> the Earth’s population live in
cities, the importance <strong>of</strong> urban air quality and climate issues do not have a high
impact on urban planning processes despite the fact that urban weather and
climate is essential for human well-being.
<strong>The</strong> main objective with the present study is to investigate how urban green
spaces impact on the air quality and the microclimate in cities. Each section
examines an urban climatic process and how this process differs in an urban
environment which includes vegetation. <strong>The</strong> final section discusses how urban
green spaces can help ease the local consequences <strong>of</strong> climate change..
Key words
<strong>Urban</strong> climate; <strong>Urban</strong> air quality; <strong>Urban</strong> green space; <strong>Urban</strong> landscapes; Environmental
planning

1. Introduction
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“<strong>Urban</strong> green spaces are public and
private open spaces in urban areas, primarily covered by vegetation
which are directly (e.g. active or passive recreation) or indirectly (e.g.
positive influence on the urban environment) available for the users.”
2. Aims <strong>of</strong> the study
European Commission Seventh

Framework ProgrammeProject <strong>Green</strong> Surge 1
3. Research methods
Google 2 Google Scholar 3
ScienceDirect 4 SpringerLink 5

4. Discussion
4.1. <strong>The</strong> planetary boundary layer above cities
Figure 1

Figure 1 – Structure <strong>of</strong> the urban boundary layer. SVF is the sky view factor
Source: COLLIER, C. G. (2006)

4.2. Energy exchanges and flows in urban environments
Earth’s
Sun

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Table 1
Table 1 – Some typical albedo values <strong>of</strong> urban surfaces
Source: NAGY, I. (2008)
Surface type
Albedo

Table 2
Table 2 – Mean monthly albedo values <strong>of</strong> different types <strong>of</strong> urban and rural
land coverage.
Category names: CDWN – city downtown, HDR – high density residential, COUT – outlying
city, MDR – medium density residential, LDR – low density residential, PFOR – forested
park, FDEC – deciduous forest, FEVG – evergreen forest, WFOR – forested wetland, WNF –
non-forested wetland, AG – agriculture, RANG – range, PNF – non-forested park, L – lake
Source: BREST, C. L. (1987)
<strong>Urban</strong> area
Suburban
area
Tree vegetated
area
Non-tree vegetation
Water
surface
CDWN
HDR
COUT
MDR
LDR
PFOR
FDEC
FEVG
WFOR
WNF
AG
RANG
PNF
L

Sky View Factor (SVF)
a
HW
Figure 2
Figure 2 – Three 180° fisheye photographs <strong>of</strong> particular sites <strong>of</strong> Göteborg
and their SVF.
(a) Open square, SVF=0.93; (b) street intersection, SVF=0.47; (c) street canyon, SVF=0.29
Source: ELIASSON, I. (2000)

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4.2.1 Energy exchanges and flows in urban environments with vegetated
areas
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(Figure 3)

Figure 3 – Some typical urban green spaces with their rate <strong>of</strong> tree-coverage
and sky view factor in Tel Aviv
Source: COHEN, P. – POTCHTER, O. – MATZARAKIS, A. (2012)
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4.3. Advection characteristics in the urban atmosphere
Figure 4
Figure 4 – <strong>Urban</strong> heat island circulation (UHIC) or country breeze and park
circulation (PC) or park breeze
Source: ELIASSON, I. – UPMANIS, H. (1999)

(Chapter
2.1)
(Figure 4)

4.4. Humidity <strong>of</strong> urban air and how urban green areas affect it
4.5. Precipitation and run<strong>of</strong>f in urban environments
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4.6. <strong>The</strong> urban heat island
urban heat island(UHI)phenomenon
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Table 3
Table 3 – Suggested causes <strong>of</strong> the urban heat island
Source: OKE, T. R. (1982)
Layer
Altered energy balance terms
leading to positive thermal
anomaly
Features <strong>of</strong> urbanisation
underlying energy balance
changes

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Chapter 8
4.7. Air pollution in cities

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Section 1

isoprene
4.8. <strong>Impact</strong>s <strong>of</strong> climate change in cities and how urban green spaces can
help
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(Sections 1–6)

Figure 5 – Maximum surface temperature in high-density residential areas,
with current form and when 10 per cent green cover is added or removed.
Dashed line shows the temperature for the 1961–1990 current form case.
Source: GILL, S. E. et al. (2007)
Figure 6 – Maximum surface temperature in town centres, with current
form and when 10 per cent green cover is added or removed. Dashed line
shows the temperature for the 1961–1990 current form case.
Source: GILL, S. E. et al. (2007)

Figure 5 and 6
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5. Conclusion
Acknowledgements
András Takács-SántaEötvös Loránd University

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