The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences. Vol. XXXVII. Part B7. Beijing 2008 
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except the Dongxi Lakes. From 1991 to 1996 the vegetation 
fraction was lightly increased in the whole study area, rose 
1.6%. From 1996 to 2002 is the period which vegetation 
fraction decreased the most sharply in this period, dropped 
7.4%.The average vegetation fraction of the whole area from 
1988 to 2002 was decreased from 58.41% to 50.45%, 
especially in Jiangxia district and the central district. 
□ 0.0 
ED 0 2-0-4 
I 10.4-0.6 
m o. 6-0.8 
Figure.3 The vegetation fraction in the study area on 
Oct 26, 1988(a), Oct 23, 1991(b), Oct 4, 1996(c) and 
Oct 13, 2002(d) 
3.3 Relationship between LST and vegetation fraction 
Previous studies of relationship between vegetation and 
temperature[ 16-18] have proposed a new method ‘ triangle 
method’, by which the relationships of three parameters, (i.e., 
vegetation, surface moisture availability and temperature) were 
discussed. In this study, scatter plots were used to study the 
relationships between brightness temperature and vegetation 
fraction. The results are presented in Fig 4, and 
the character of the space is nearly triangle. Because when 
NDVI reached 0.6 or more, where 100 percent vegetation 
fraction was identified, spatial characteristics of the show were 
not entirely a triangle. 
Fig 2 and Fig 3 show that there was strong negative 
relationship between LST and vegetation fraction with 
brightness temperature. It is presented the Vegetation change 
contributed to the global warming and effected UHI intensity 
mainly through the processes of urban sprawl, degradation of 
cropland in this study. 
Therefore, we also use the regression analysis to present the 
relationships quantitatively compared with ‘triangle method’. 
An analysis based on linear regression showed that the 
coefficient of determination value (R A 2) of Wuhan between the 
above factors was 0.867, 0.843, 0.841, 0.843 of 1988, 1991, 
1996 and 2002. 
Vegetation fraction in different 
time ( % ) 
The change of vegetation fraction in 
different time ( % ) 
1988 
1991 
1996 
2002 
1988-1991 
1991-1996 
1996-2002 
caidian 
57.36 
58.89 
58.68 
49.99 
1.53 
-0.21 
-8.69 
hannan 
48.15 
52.25 
53.37 
43.76 
4.1 
1.12 
-9.61 
jiangxia 
57.71 
56.61 
59.38 
47.73 
-1.1 
2.77 
-11.65 
The center urban 
50.45 
51.76 
53.67 
43.30 
1.31 
1.91 
-10.37 
The whole region 
58.41 
56.20 
57.85 
50.45 
-2.21 
1.65 
-7.4 
Table. 2 Dynamics of vegetation fraction in different districts of Wuhan in 1988, 1991, 1996 and 2002 
4. CONCLUSION 
In this paper, qualitative and quantitative analyses have been 
used to study the change of UHI, vegetation fraction and the 
relationship between those in Wuhan. Several conclusions were 
made: (1) distribution of heat island has been expanded rapidly 
in Wuhan, especially in the center urban; (2) vegetation 
fraction in Wuhan has decreased through 14 years; (3) the 
change of vegetation fraction affected UHI intensity, the 
character of the space between vegetation fraction and 
temperature is nearly triangle; and there also had a strong 
negative relationship between vegetation fraction and 
temperature, the coefficient of determination value (R A 2) in 
different times were larger than 0.8. 
In future study, several works need to future focused. Firstly, 
remote sensing images needs to be improved to reduce the 
influence of thin cloud and inhomogeneous atmosphere 
condition. Secondly, the impact of the distribution of 
vegetation fraction in the urbanized area on UHI needs to be 
further studied. 
ACKNOWLEDGMENTS 
This study was supported by Chinese National 863 program 
(2007AA12Z148 , 2007AA12Z181) and National Science 
Foundation of China grant NO. 40771139, 40523005. 
The results showed that although remote sensing images were 
ideal for analyzing UHI and vegetation fraction, it is difficult to 
select images with similar condition of atmosphere, hydrology.