To analysis the change of UHI, Urban Heat Index (URI) was
introduced, which was based on the ratio of UHI area to urban
area. The greater the index is, the more intense of the UHI is.
The trend of UHI showed a obvious trend: as the urban area
expanded, the URI of Wuhan consistent increased, especially in
1991. The URI from 1988 to 2002 were 0.134, 0.153and 0.170,
respectively.