ESTIMATING URBAN TEMPERATURE BIAS USING POLAR-ORBITING SATELLITE DATA

Urban temperature bias, defined to be the difference between a shelter temperature reading of unknown but suspected urban influence and some appropriate rural reference temperature, is estimated through the use of polar-orbiting satellite data. Predicted rural temperatures, based on a method developed using sounding data, are shown to be of reasona ble accuracy in many cases for urban bias assessments using minimum te mperature data from selected urban regions in the United States in Jul y 1989. Assessments of predicted urban bias were based on comparisons with observed bias, as well as independent measures of urban heat isla nd influence, such as population statistics and urban-rural difference s in a vegetation index. This technique provides a means of determinin g urban bias in regions where few if any rural reference stations are available, or where inhomogeneities exist in land surface characterist ics or rural station locations.