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ABSTRACT
Dissertação de Mestrado
Programa de Pós-Graduação em Geografia e Geociências
Universidade Federal de Santa Maria
THERMAL FIELD AND URBAN HEAT ISLANDS ESTUDY IN SANTA MARIA-RS
Autor: Alexandre Pistoia Saydelles
Orientadora: Prof.ª Dr.ª Maria da Graça Barros Sartori
Data e Local da Defesa: Santa Maria, 29 de Março de 2005.
The objective of this work was to analyze the thermal field and the urban heat islands in Santa
Maria and its surroundings, relating their thermal and spatial behaviors throughout both urban
and natural interaction, facing the imposition of types of weather originated from Prefrontal
Phase and Polar Domain atmospheric conditions, during the winter. The Thermal Dynamic
Urban Weather System climatic perception channel, indicated by Monteiro (1976), was used
as preliminary theoretical-methodological foundation. The study was developed in three
phases. The first one was centered in elaborating the research goals. The second one was
divided into two parts that consisted in the spatial analysis by elaborating thematic mapper,
with the objective of making it possible to characterize geo-ecological and geo-urban variants
inside the area in study, also in the analysis of the thermal field, in the MESO and TOPO
weather scales, using image from the Landsat 7 ETM Satellite, on 06/19/2002. Field
experiments inside the city were made in order to study the urban heat islands, in which 19
mini meteorological shelters were distributed with the objective of measuring the air
temperature at 09h, 12h, 15h, 18h and 21h, on 08/04/2004 e 08/10/2004. Information on the
air temperature was spatialized in isothermal cartograms over the Surfer6 program.
Rhythmical analysis charts with daily meteorological data taken from the Santa Maria
Meteorological Station, plus images from the GOES-E Satellite were elaborated to defined the
types of weather traced in the days of the thermal image and from field observation. The third
phase of this work consisted in the analysis of the results from the interpretation of the digital
thermal cartography of surface, in which was possible to discern that the factors relief,
vegetation, altimetry and use of rural soils control the mesoclimatic thermal responses. The
greatest diversification in thermal responses detected concerned the topoclimate, due to the
natural and urban factors, also to the Sun position during the imaging time, which have
defined four distinct thermal situations: Warmer areas, with temperatures between 17° and
19°C; Moderate temperature areas, between 15° and 18°C; Mild temperature areas, between
13° and 17°C; and Lower temperature areas, between 10° and 16°C. Analysing the field
experiments, it was possible to discern that on 08/04, due to the “North Wind” action in the
dissipation of the thermal responses, there was no significant formation of “Urban Heat
Islands” (UHI). Although, on the second day (08/10), under summarized Polar Domain
conditions, the city registered UHI formation of high magnitude at every hour of observation,
as well as the highest center-periphery thermal amplitude (10°C, at 12h). This way, it is
possible to assert that the imposition of regional atmospheric systems acts directly in the
definition of the thermal field and in the UHI formation, therefore being considered to
effectuate a better urban planning and a greater understanding of the local climatic variants.