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theoretical frame of urban climatology. Synthesis from this period is included in the
topics by Landsberg [LAN 81] and Fezer [FEZ 95], in the chapter of Oke's topic on
the boundary layer climates [OKE 87], and in the papers by Oke [OKE 88] and
Lowry [LOW 77; LOW 98], among many others.
5.2.3.
Urban climate in beginning of the 21
st
century
During the first years of this century intense activity has been channeled into the
development of monitoring techniques and modeling, into the study of urban climate
in tropical and arid regions (or threatened by desertification) and in a wide
dissemination of the latest results. Urban climate knowledge and methodologies
have been broadly disseminated through the international conferences promoted by
the International Association on Urban Climatology (IAUC) created in 2000 and its
Newsletters (named
Urban Climate News
since March 2008) available at the IAUC
internet site (http://www.urban-climate.org/) and through the International Urban
Climate Homepage (http://www.stadtklima.de). Furthermore, some members of the
IAUC have acted as guest editors for two special issues on urban climate of peer-
reviewed international journals [
Theoretical and Applied Climatology
(vol. 83,
2006) and
International Journal of Climatology
(vol. 27, 2007)].
The present chapter is partly based on current methods, discussed in both
journals and in recent literature, related to the assessment of urban climate.
Modeling and the use of GIS are presented through examples involving Lisbon
where a group of scholars have focused their research in urban climatology for the
past two decades.
5.3. Spatial scales
The concept of scale is of paramount importance in urban climatology. Several
horizontal and vertical spatial scales have been proposed by different authors. Oke's
proposals [OKE 06a] will be followed in this Chapter, albeit in a simplified way.
Research on the urban environment may be carried out at different spatial scales,
from the microscale to the mesoscale (Figure 5.1). The study of street, road,
courtyard, and garden climate is carried out at the
microclimatic scale
, ranging
typically from less than 1 m to hundreds of meters [OKE 06b]. The
local scale
translates the climate of city districts with similar built-up density, percentage of
impervious surface, urban canyon geometry, activity, etc. One type of local climate
(such as city-center climate) includes a mosaic of microclimates, and its signal may
be captured in a meteorological station, integrating the microclimatic effects from
nearby areas. Typical scales range from 1 to several kilometers [OKE 06b]. The
mesoclimatic conditions of a town integrate several local climates. It can only be
inferred from data provided by several stations scattered within the urban
agglomeration. Typical scales are tens of kilometers [OKE 06b]. Examples of
mesoclimatic and microclimatic approaches in the city of Lisbon are presented in
5.7 and 5.8.
