Biases Associated with Air Temperature Measurements near Roadways and Buildings

Proximity to buildings and paved surfaces can affect the measured air temperature. When buildings and roadways are constructed near an existing meteorological site, this can affect the long-term temperature trend. Homogenization of the national temperature records is required to account for the effects of urbanization and changes in sensor technology. Homogenization is largely based on statistical techniques, however, and contributes to uncertainty in the measured U.S. surface-temperature record. To provide some physical basis for the ongoing controversy focused on the U.S. surface temperature record, an experiment is being performed to evaluate the effects of artificial heat sources such as buildings and parking lots on air temperature. Air temperature measurements within a grassy field, located at varying distances from artificial heat sources at the edge of the field, are being recorded using both the NOAA US Climate Reference Network methodology and the National Weather Service Maximum Minimum Temperature Sensor system. The effects of the roadways and buildings are quantified by comparing the air temperature measured close to the artificial heat sources to the air temperature measured well-within the grassy field, over 200 m downwind of the artificial heat sources.