Urbanization effect on soil temperature in Nanjing, China

Temporal and spatial changes in soil temperature were monitored in rural and urban areas within Nanjing city, China to investigate the influence of increasing urbanization. Diurnal changes in soil temperature as a function of depth (i.e., 10, 20, 30, 40, 50, 60, 100 and 150 cm below ground surface) were measured continuously for one year (from June 2009 to June 2010) at two locations. Soil temperature was also measured at selected times at 600 locations within urban and rural areas. The results show that both the urban and rural soil temperature profiles are strongly tied to the prevailing air temperature, while the synoptic influence on soil temperature occurs mostly at depths less than 60 cm. Based on spatial averages for the studied one year period, the urban soil is 1.21 degrees C warmer than the rural soil. The nature of the temporal and spatial changes in soil temperature varies according to whether a given location is rural or urban. The average daily, monthly and seasonal difference ranges from 0.29 to 3.03 degrees C, 0.62 to 2.0 degrees C and 0.84 to 1.51 degrees C, respectively, between urban and rural locations. Soil temperature variations generally decrease with increasing depth and increase with urbanization. (C) 2011 Elsevier B.V. All rights reserved.