Evaluation in the Bias of Temperature Measurements Based on Siting Criteria Used for Climate Observing Systems

Accurate temperature measurements are required for climate models and the determination of climate trends. Uncertainty in air temperature measurements causes uncertainty in climate models, as historical air temperature data are used to test climate models. Air temperature monitoring systems are placed in different types of landscapes and geographical areas that can introduce environmental biases caused by the presence of buildings and pavement. There has been little research done on quantifying such biases. This experiment attempts to quantify these biases by taking temperature measurements at different distances from buildings and pavement. Data was collected for about 1.5 years. Four identical aspirated temperature sensors were used to measure the air temperature. In addition to air temperature, wind speed, wind direction, incoming and outgoing radiation, and surface temperature were also measured. By the end of the experiment it was determined that the environmental bias was higher on the tower closest to the buildings compared to the tower farthest away from the buildings. Low wind speeds also showed higher temperatures. Our results indicate that low wind speeds and proximity to buildings and roadways contribute to positive biases in air temperature.