The comparison of vegetation index and surface temperature composites for urban heat-island analysis

Relationships between urban-rural differences in minimum (in situ) air temperature (T-min), normalized difference vegetation index (NDVI), and apparent surface radiant temperature (T-sfc) were examined for 28 cities in the U.S.A. from 28 June through to 8 August 1991. Composites based on NDVI and thermal-IR data, and consistency in urban-rural differences in NDVI and T-sfc were examined. The urban-rural differences in T-sfc, whether based on an NDVI composite or a composite based on thermal-IR data, were not as consistent as the urban-rural differences in NDVI. The composite process utilized, based on NDVI or thermal-IR data, did not appear to contribute to the generally low correlation between urban-rural differences in T-min and T-sfc observed in previous studies.