| Rapid urbanization resulted in the the change between natural environmentand the impervious ground, and which has caused the servious thermal environment problems. The increase of the thermal environment can bring negative effect on the economy, ecology, as well as the living of city residents. The urban green spaces play an important role in the mitigation of urban heat, and accordingly can help the city adapt to the urban climate change. With the help of RS and GIS, three periods (1988,2000,2009) of TM/ETM+were used to retrieve land surface temperature, and interpret land use patterns, in addition, urban green spaces information were obtained through high resolution data of IKNOS in2009; then landscape metrics, moving window and gradient analysis are employed to find the relationship between green biomass, green space pattern and cold island effect, accordingly a model were developed to predict the influence of differenct landscape characteristic of green spaces. At last, based on the research of this thesis, suggestions on the urban green space planning and development for their better cooling effect were given.This thesis was constructed by six chapters. The first chapter introduced the, s paper’s background, significance, ideas, the basic framework of research as well as the description of the study area. The second chapter reviewed the related research. The third chapter gave a general expalnaton on the data and research method used in this thesis, such as single window algorithm of retrieving land surface temperature and moving window of landscape patter analysis. The fourth chapter and the fifth chapter are the main parts of this thesis. The fourth chapter analyzed the landscape characteristics the green spaces of study area and the cold island pattern from spatio-temporal scale. The fifth chapter discovered and analyzed the factors which may affect the cold island intensity caused by the cooling effect of green space, and on the basis of which, a prediction model to calculate the cold island intensity was developed. The sixth chapter is the conclusions. It systematically summarized the main conclusions and innovations of this research, and put forward the disadvantages and the direction future research would study and perfect. The results showed as follows:(1) During the past two decades, the land-use in Nanjing city has undergone tremendous changes, mainly showing as the in the increase of urban areas and decrease of urban green spaces and farm land. However, the landscape spatial pattern analysis shows that the fragmentation, landscape shape index and aggregation of the urban green space had a trend of decreasing at the first10years and then increased in the recent10years. The moving window and the gradient analysis showed that landscape shape index (Landscape Shape Index, LSI) on green class level decreased gradually from the center outwards, which coincident with urban built-up exploration; while in the temporal scale, the aggregation of green (AI) increased slightly in the central region, while decreased away from the central region, indicating that with the outlying region being urbanized, green space distribution became more and more discrete, and the green shape complexity (LSI) was becoming more complexed.(2) The cold island landscape and gradient analysis showed that the high temperature region expanded with extension of the built-up, the low temperature region was reduced with the reduction in the area of natural vegetation, but the cold island patch number was increasing rapidly, indicating that as the fragmentation of green cool island raising gradually, the shape becomes more and more complex.(3) Two different ways were tried to describe the intensity of cold island, that were NDCII (Normalized Difference Cool Island Intensity) and the temperature difference between inside and outside of green patch. Statistical results of mean temperature of five land-use classes showed that except for water areas, green space are the lowest, and next is the farmland. In addition, the watershed analysis model based on digital elevation model was introduced to analyze the distribution of the temperature watershed in Nanjing, and the results showed that with the upheaval of the natural vegetation and the urban area, the pattern of low temperature lines changed significantly.(4) Take Qingliangshan Park as example, the characteristics of cold island landscape caused by cooling effect of the green space had been analyzed. The results showed that its cooling ranges were different in different directions for surrounding terrain. The cooling gradient magnitude of Qingliangshan Park was affected by the surrounding terrain. Over all, distance from the park border increased for each additional10m temperature raises about0.368℃, and the cooling distance was no more than130m. To study the cooling effect of the road green belt, we analyzed the cooling effect of eight samples with typical canopy road green belt. The results showed that the green belt canopy with the width of20m, temperature was0.4℃lower compared to the surrounding area. With the Green Belt tree canopy width increasing for each additional10m, the cooling rate increased by0.33℃.(5) On the scale of landscape, the statistical analysis showed that green biomass presented a significant positive correlation with the cooling effect, in addition, LSI and AI showed a significant negative and a positive correlation respectively. Finally, the model between green patch NDCII and the temperature difference inside and outside green patch was developed, and the accuracy of this model was proved. |
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