AN ASSESSMENT OF SATELLITE REMOTELY-SENSED LAND-COVER PARAMETERS IN QUANTITATIVELY DESCRIBING THE CLIMATIC EFFECT OF URBANIZATION

The regional-scale climatic impact of urbanization is examined using t wo land cover parameters, fractional vegetation cover (Fr) and surface moisture availability (M-0) The parameters are hypothesized to decrea se as surface radiant temperature (T-0) increases, forced by vegetatio n removal and the introduction of non-transpiring, reduced evaporating urban surfaces. Fr and M-0 were derived from vegetation index and To data computed from the Advanced Very High Resolution Radiometer (AVHRR ), and then correlated to a percentage of urban land cover obtained fr om a supervised classification of Landsat TM imagery. Data from 1985 t hrough 1994 for an area near State College, PA, USA, was utilized. Urb an land cover change (at the rate of >3 per cent per km(2) per year) w as statistically significant when related to a decrease in normalized values of Fr and increase in normalized values of T-0. The relationshi p between urbanization and M-0, however, was ill-defined due to variat ions in the composition of urban vegetation. From a nomogram of values of Fr and T-0, a Land Cover Index (LCI) is proposed, which incorporat es the influence of local land cover surrounding urbanized pixels. Suc h an index could allow changes in land use at neighbourhood-scale to b e input in the initialization of atmospheric and hydrological models, as well as provide a new approach for urban heat island analyses. Furt hermore, the nomogram can be used to qualify urbanization effects on e vapotranspiration rates.