Investigating the Urban Heat Island Effect with a Collaborative Inquiry Project

Article excerpt

ABSTRACT

Modification of the earth's surface through urbanization can have a dramatic impact on local climate. A phenomenon known as the Urban Heat Island (UHI) effect, which is a measure of the near-surface air temperature contrast between urbanized and adjoining rural areas, can be evaluated with readily available instruments. Students in an undergraduate general education science course study this phenomenon in the Portland, Oregon area through a collaborative research project. This inquiry project includes background content and literature review, preliminary studies, development of research questions, experimental design and implementation, data analysis and report writing. This project successfully enables students to collaboratively generate a data set that is amenable to sophisticated and interesting analysis and provides an opportunity to study a phenomenon in their local environment.

Keywords: undergraduate education, collaborative inquiry.

INTRODUCTION

Urban heat islands are characterized by "islands" of warm surface air centered on urbanized landscapes and surrounded by progressively cooler air over suburban/rural areas. The urban-rural surface air temperature contrast varies diurnally and is one measure of the urban heat island (UHI) effect. Urban heat islands result from factors that differentiate the urban from the non-urbanized landscape, including: anthropogenic energy releases from heating-ventilation-air conditioning systems, energy emissions from industrial processes and motorized vehicles, the amount of available surface moisture and the differential heat capacities of urban building materials versus natural structures. The magnitude and spatial scale of UHI effects have increased in urban areas around the world and have implications for the transport of air pollutants, modification of bioclimatic conditions, heating and cooling costs and the confounding of long-term temperature records. The investigation of UHI effects provides numerous avenues of exploration that are both topical and relevant to students lives - characteristics that promote successful classroom implementation of science inquiry projects (McNeal and D'Avanzo, 1997).

This paper documents the process used for our Urban Heat Island classroom research project in our undergraduate "Atmospheric Interactions" course and discusses some of the outcomes both in terms of scientific results and achievements in student learning. The course is an upper division undergraduate general education science course that is taken primarily by students not majoring in science to fulfill degree requirements. The objective of the course is to study the physical and chemical properties of the atmosphere through lecture and field studies. We pay particular attention to the impact of human activities on the atmosphere.

This Urban Heat Island project is designed to parallel a scientific research process as it takes the students through literature review, preliminary studies, development of research questions, experimental design and implementation, data analysis and report writing. As an instructional approach it has the following features: it is situated in a meaningful real-world context; it provides students with an opportunity to deepen their understanding of physical principles through application; it requires classroom collaboration combined with significant individual effort; it incorporates an appropriate use of technology and it requires the communication of the analysis in the rhetorical style of a scientific paper. The design and implementation of this project is consistent with science inquiry pedagogy recommended by national organizations to be a part of undergraduate science education (NSF, 1996, Society for College Science Teachers, 1998).

OVERVIEW OF THE URBAN HEAT ISLAND EFFECT

There are numerous on-line and text references that provide good coverage of the basics of boundary layer meteorology and the urban heat island effect (for example - Akbari, 2002, Arnold, 1999, Ahrens, 1994, Turco, 1997, Stull, 1988). …