The Use of Low-cost Data Logging Temperature Sensors in the Evaluation of an Urban Heat Island in Tampa, Florida

The detailed study of the urban environment did not really begin until the start of the 20 century. Early studies by Fassig (1907), Saucier (1949), and Ligda and Bigler (1956) established the hypothetical down-wind effect of cities, while studies by Woollum and Canfield (1968) helped in localizing the hypothesized downwind effect of cities. As the evidence for the modification of weather by urban areas began to amass, Changnon (1968) produced a report on the La Porte precipitation anomaly downwind of Chicago. The Changnon La Porte study brought about an awakening of researchers and the general public to the possibility that urban areas were having an effect on the weather. In the wake of the Changnon report, in 1971 four research teams came together in St. Louis, Missouri, in an effort to study the weather modification induced by the urban-industrial environment. As a result of the collaboration, the St. Louis METROMEX field project was undertaken. Prior to the METROMEX project, urban-related climate modification had been studied only to a limited degree. In order to more fully document the Urban Heat Island (UHI) phenomenon and the effects that urban areas were having on weather modification, the METROMEX study employed a dedicated network of sensors over a period of 5 years. By definition, a UHI is characterized as higher air temperatures in urban areas than in the surrounding rural locations. Historically, in UHI research, the records of local established weather monitoring sites have been used in the gathering of data for UHI analysis. To more fully document the characteristics of the urban environment, the St. Louis METROMEX study employed 220 rain gauges and hail pads distributed evenly over an area of 5700 square kilometers in and around St. Louis, Missouri. Three radar sites were employed to gather firstecho rain data in the study area. Radiosondes were deployed to gather data on upper atmospheric conditions, and aerosol samplers were used to detect cloud condensation nuclei concentrations and air pollutants in and around the city. The St. Louis METROMEX study was the first research effort to attempt to adequately document the specific characteristics within an urban area that might be influencing the climate. It should be noted that the METROMEX study initially employed just 7 weather stations to record temperature data. This was increased to 25 temperature reporting weather stations later in the study period. The low number of temperature recording stations in the METROMEX study, deployed in a large survey area, may have limited the research team’s ability to accurately correlate any changes in weather characteristics that might have been attributed to the UHI. Other researchers have also investigated the UHI using the traditional approach of gathering data from local weather stations in addition to the installation of small networks of field sensors. Bornstein and Lin (2000) studied summertime thunderstorms in Atlanta, Georgia, and found that the UHI induced a convergence zone that initiated thunderstorms. Dixon and Mote (2003) also investigated Atlanta, with similar results. A limiting factor in these two studies was the size of the temperature sampling network used. The Dixon and Mote study utilized 10 recording weather stations situated over a 21 county area, while Bornstein and Lin utilized 42 recording weather stations spread over a 105,000 km study area. The number