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Air Temperature Reductions at the Base of Tree Canopies
Citation:
Razzaghmanesh, M., M. Borst, J. Liu, F. Ahmed, T. Oconnor, AND A. Selvakumar. Air Temperature Reductions at the Base of Tree Canopies. Journal of Sustainable Water in the Built Environment. American Society of Civil Engineers (ASCE), New York, NY, 7(3):04021010, (2021). https://doi.org/10.1061/JSWBAY.0000950
Impact/Purpose:
This paper provides results that will help municipal planners position urban trees to obtain benefits not only from from stormwater mitigation but also from temperature reduction
Description:
Urban trees, either as standalone plantings or as part of a tree pit, are a popular stormwater management tool. Beyond the aesthetic contribution to urban environment, trees are widely accepted as reducing ambient air temperature. There is, however, limited quantitative information regarding the temperature mitigation performed by urban trees. This study monitored air temperature at locations throughout the city of Camden, NJ. Sensors were installed under trees of different sizes throughout the city using a statistical experimental design. The tree size (small or large) and canopy (intersecting or non-intersecting), along with street orientation (predominantly north-south or east-west) and analysis period (daylight, nighttime, or full day) were experimental design factors. Sensors attached to poles served as controls. This study recorded temperatures at 10-minute intervals from early August through late November 2017 using logging thermistors mounted in radiation shields about 4 m above the ground surface. Maximum daily air temperature measured at heights of 4 m above the ground surface at control sites was used to divide data into three categories: hot, average and cold. The groups were analyzed separately using Analyses of Variance to test the significance of the categorical variables. During hot days (maximum temperature larger than 30°C), there were meaningful statistical differences between recorded mean air temperatures under trees with intersecting canopies and the control sites. Comparison of street orientation for hot and average days when divided into night and day category showed during day times, east-west streets were hotter than north-south streets and a reverse pattern was noted for the night times. For cold days, there was no difference for the studied categorial factors.
URLs/Downloads:
DOI: Air Temperature Reductions at the Base of Tree Canopies
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