First Advisor

Vivek Shandas

Date of Award

6-14-2024

Document Type

Paper

Degree Name

Master of Science (M.S.) in Geography

Department

Geography

Language

English

DOI

0.15760/geomaster.29

Abstract

Cities are significantly warmer than their surrounding rural environments. Known as the ‘urban heat island effect’, it can affect the health of urban residents and lead to increased energy use. Although this effect is extensively researched, less is known about how landscape characteristics within cities affect local temperature variation. With a warming climate and the need for heat mitigation strategies becoming more urgent, having a finer detailed understanding of the effects on temperature is critical to guide proper management policies. This study examined how tree canopy cover, canopy volume, and impervious surface cover affect daytime near surface air temperature, and how these effects vary between different scales of analysis (10, 30, 60, 90 m radii), ranging from approximate street corridor to city block size. Temperature data was obtained from a car mounted sensor, with traverse data points recorded during morning, afternoon, and evening times, plotted throughout the city of Portland, OR. The variability in near surface air temperature was over 10° F during each traverse period. Near surface air temperature increased linearly with impervious surface cover and decreased linearly with tree canopy cover, with canopy volume reducing temperature by 1° F for every 500 cubic feet of canopy volume for evening temperatures. Magnitude of the effect of tree canopy increased with spatial scale, with 60- and 90-meter scales having the greatest coefficient value. Canopy volume had a positive relationship on presumed nighttime and early morning temperatures at 60- and 90-meter scales, potentially due to impacts in wind fluctuation and air roughness, though canopy cover still had a larger overall negative relationship with temperature. Increasing tree canopy cover and volume effectively explained lower daytime and evening temperatures, while reducing impervious surface cover remains critical for reducing morning and presumed nighttime urban heat. Results may inform strategies for urban foresters and planners in managing urban land cover and tree planting patterns to build increased resiliency towards moderating urban temperature under warming climate conditions.

Rights

In Copyright. URI: http://rightsstatements.org/vocab/InC/1.0/ This Item is protected by copyright and/or related rights. You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s).

Comments

A research paper submitted in partial fulfillment of the requirements for the degree of Master of Science in Geography.

Persistent Identifier

https://archives.pdx.edu/ds/psu/42405

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