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geometry, street orientation, and land cover, so that the causes of microclimatic
differences could be inferred (Figure 5.4c and 5.12) [AND 08].
5.5.3.
Remote sensing
In this topic, Chapter 3, written by V. Dubreuil, is dedicated to remote sensing.
Additionally, there are a large number of publications on urban remote sensing
[PAR 98; GRI 06b]. Satellite images have the ability of depicting several parameters
of the urban areas with great detail (land cover, surface UHI, surface-atmosphere
exchanges, radiation and energy balances, evaporation, carbon fluxes, among many
others) and may be used combined with other techniques. Surface UHI and energy
balance studies have been carried out in Lisbon [LOP 01; LOP 03] using remote
sensing.
5.5.4.
Intensive measuring campaigns
Large campaigns to monitor the urban climate are cited by Grimmond, who
writes “increasingly, urban-based observational programs are collaborative, multi-
institutional, multinational, interdisciplinary initiatives” [GRI 06b, p. 3]. These
initiatives have the advantages of i) encouraging the research on processes and
effects at different time and space scales; ii) being able to afford technically
advanced instrumentation; iii) facilitating the common use of expensive instruments
by several institutions; iv) conveying a greater awareness of the importance of
appropriate placement of instrumentation; v) enabling faster and more sophisticated
data analysis [GRI 06b].
Let us present data acquisition within the Escompte Project as an example. “The
principal aim of the ESCOMPTE program was (..) to provide a comprehensive data
base for the purpose of developing and validating models referring to air pollution in
the region of Marseille, France, both at the mesoscale and the local scale”.
(http://www.cnrs.fr/cw/en/pres/compress/escompte.htm). However, in order to
understand pollutants concentration, it is necessary to be acquainted with the UBL
and suburban boundary layer dynamics. This has been carried out through an
intensive measurement program using a)
ground-based instruments
, such as i) radars
and sodars (Doppler acoustic sounders), ii) wind-profiling radars, iii) lidars in order
to measure the quantity of transported ozone, iv) radiosounding, v) permanent
chemical measuring stations, vi) many temporary stations (to measure climate,
surface energy or chemical compounds), vi) a site equipped for the measurement of
the principal meteorological parameters and chemical compounds (reference station
at Le Planier); b)
air-borne instruments
such as equipped airplanes and constant
altitude balloons launched in daytime, under coastal breeze conditions, to provide
in-depth information on the extent of wind penetration into the mainland and into
the areas affected by the pollutant combinations emanating from Marseille and
the Fos-Berre industrial basin; c)
sea-borne instruments
aboard two ships
equipped with chemical and atmospheric measurement tools (adapted from
http://escompte.mediasfrance.org/projet/projets/CLU/).
