Green Areas and Microscale Thermal Comfort in Arid Environments: A Case Study in Mendoza, Argentina

Salvador Enrique Puliafito,Fabián Rolando Bochaca,Rafael Fernandez,David Gabriel Allende

doi:10.4236/acs.2013.33039

Salvador Enrique Puliafito, Fabián Rolando Bochaca + Show 2 more

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https://doi.org/10.4236/acs.2013.33039

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Abstract

A series of mobile and stationary meteorological measurements were performed in the city of Mendoza, Argentina to study the local influence of green areas on the urban canopy layer heat island effect at the micro scale, during the Austral summer of 2003-2005. These results were associated in representative local climate zones (LCZ), which helped to identify different thermal conditions within the city. The physiologically equivalent temperature index was used to determine the thermal comfort in each LCZ, showing that during daylight, trees and parks improve thermal comfort through shading and evapotranspiration; but at the same time, urban tree corridors delay night cooling by retaining warm air beneath their canopies. Also irrigation showed to positively influence on the extension and intensity of the cooling effect of rural areas and parks. The cooling influence of an urban park spreads out through the neighborhoods for 800 - 1000 m, with an average temperature decrease of 1.3°C during daytime and >4.0°C at nighttime.

Highlights

Increasing urbanization rates are associated with changes in land use and land cover (LULC), air pollution and a higher demand for energy and water consumption
The physiologically equivalent temperature index was used to determine the thermal comfort in each local climate zones (LCZ), showing that during daylight, trees and parks improve thermal comfort through shading and evapotranspiration; but at the same time, urban tree corridors delay night cooling by retaining warm air beneath their canopies
To answer to the above questions, the following research methodology was adopted: 1) Local Climate Zones (LCZ) [25] were assigned to the city of Mendoza using LULC maps; 2) a mobile traverse was design to monitor temperature (T) and relative humidity (RH) in each LCZ type; 3) T, RH was evaluated at each measuring point (MP); 4) a thermal comfort index was calculated using the Physiologically Equivalent Temperature (PET) [26]; and 5) meteorological surface data from fixed stations was used to evaluate the influence of irrigation at an urban park in Benegas

Summary

Introduction

Increasing urbanization rates are associated with changes in land use and land cover (LULC), air pollution and a higher demand for energy and water consumption These anthropogenic changes have increased the temperature difference between urban and rural or peripheral environments, the effect of which is known as “urban heat island” (UHI). At the horizontal scale three zones may be identified [1, 2]: 1) the micro scale, from individual building, tree or street to a city block size (0 - 100 m); 2) the local scale, from several homogenous blocks to a neighborhood (200 - 2000 m); and 3) the regional scale, which includes the city scale (5000 - 20,000 m) These vertical and horizontal scales generate two different UHI processes: the UCL_UHI and the UBL_UHI. Other additional causes may be attributed to the increasing particle concentration from urban pollution [6,7], which can alter the energy balance of the atmosphere, increasing local air temperatures and reducing cooling rates [8]

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