The Urban Heat Island of San Antonio, Texas, from 1991 to 2010

This study aims to investigate the urban heat island (UHI) effect of San Antonio, Texas (USA), and its temporal changes over the time period 1991-2010. It is an extension of previous work that used historical air temperature data from 1946 to 1990. The study was designed to compare 20 years of daily air temperature records (1991-2010) of San Antonio, Texas (USA), with three small surrounding communities; New Braunfels, Poteet, and Boerne. These towns are all within 50 kilometers of San Antonio and have contemporary temperature records. Temperature differences between San Antonio and the surrounding communities indicate changes in the thermal environment due to urbanization. The results are as follows. The daily UHI intensity in autumn and winter is increasing and decreases in the spring and summer seasons. Autumn is the only season where the daily UHI intensity increased and spring is the only season where it decreased during the years 1991-2010. The results for Poteet and Boerne were generally similar. In June during 1997 to 2010, the daily UHI intensity in San Antonio is increasing at an average rate of 0.8°C/decade relative to New Braunfels. These results are generally consistent with previous studies. A physical model of the urban environment is described that is under development to aid in interpreting the results and for city planning. Mitigation strategies as applied to San Antonio are briefly discussed, including green roofs, and urban trees and other natural vegetation. In conclusion, despite mitigating influences, San Antonio continues to have an increasing UHI effect. However, further work is needed to connect to the previous study from 1946 to 1990 and update to the present to strengthen this conclusion.