Below Canopy Meteorological Measurements at Three Florida Sites with Varying Tree Cover and Development

Abstract

Residential demand for air conditioning is strongly impacted by the surrounding ambient air temperature. Research over several decades has documented the progressive impact of urban heat islands on summer temperatures in the built environment. However, less research has examined how the heat island is impacted by the more localized meteorological environment. How does suburban development and tree canopy cover impact micro-climates in a suburban environment? This has implications, both for preserving trees within recently constructed developments, as well as the potential impact of tree planting programs. To address this question, temperature measurements were made over a one year period at three Melbourne, Florida sites. The results showed a forested nature park of 19 hectares to be consistently cooler during both summer days and nights than a residential development of 9 hectares and density of 4.6 houses per hectare with an extensive tall tree canopy, which, in turn, was consistently cooler than a residential development of 37 hectares and density of 10.1 houses per hectare with very few trees. The average July air temperatures for the forested undeveloped site, residential site with trees, and residential site without bees measured at the project's main stations were 26.2.26.9 and 27.8" respectively at a 2.5-meter height and 26.7.27.0 and 27.7OC respectively at a 9-meter height. The 2.5-meter temperature differences were greater than 1°C between the two residential sites 93% of the time when both sites had wind speeds greater than 0.5 m/s. Secondary. remote temperature sensors grouped around the main stations in each of the three sites to account for spacial variability registered even larger temperature differences than sensors at the main stations. Mobile measurements were made on two summer days, with good agreement with the main stations. The mobile measurement made on a sunny day indicated significant localized warming at commercial sites adjacent to the residential development with trees.