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Implications of Urban Form and Topography in Thermal Conditions at Local and Micro Scale in a Tropical Urban Area Located in a Valley
  • Gisel Guzmán,
  • Carlos D Hoyos
Gisel Guzmán

Corresponding Author:[email protected]

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Carlos D Hoyos
Associate Professor
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Cities are the most sensitive and vulnerable places to climate variability and change and weather-related extreme events given high population density, with the aggravating factor that urban climate also suffers modifications due to the widespread replacement of the natural surface altering the local thermal conditions. The Aburrá Valley is a narrow valley located at the tropical Andes in northern South America with urban areas between 1300 and 2000 m.a.s.l, a population of approximate 3.9 million people, and a comfortable climate relative to standard indoor conditions. In this work, we examine observed weather patterns in the local scale and the urban canopy layer (UCL) using data from weather stations at sites with different surface features regarding vegetation/non-impervious fractions and urban structure (Sky View Factor SVF). UCL data is available from two data sources, the first one from a field campaign using all-in-one weather sensors at the valley´s bottom, and the second one from a low-cost sensor network with robust temperature and humidity data as part of a local citizen science project with measurements in a diverse altitude range. Results suggest that at the local scale there exist different climate mean conditions due to altitude, with significant weather variability depending on radiation levels and rainfall occurrence, but at the same time, the urban effects are evident since the lowest altitude stations do not necessarily register the highest temperatures depending on the local characteristics. UCL measurements show that, while the altitude defines a background state, there are notable differences between places mainly influenced by insolation changes due to vegetation around and above sensors. Currently, the local population does not perceive thermal stress as a risk factor because it is not difficult to find places with appropriate thermal conditions when thermal discomfort arises. However, this research is relevant considering the projected local surface temperature increase due to climate change and the inexistence of baseline studies assessing the thermal comfort in outdoors to support local adaptation actions. The results of this study are useful for urban planning and building design to improve thermal conditions, especially in open spaces.