Studying dynamical monitoring of heat island effect based on MODIS data in coastal cities of Southeast Fujian Province

Abstract

Global warming has obtained more and more attention because the global mean land surface temperature (LST) has increased since the late 19th century. Urban heat island (UHI) effect and its thermal environment are the most important themes in urban climatology and environment researches. One of the possible causes to UHI effect is the drastic reduction in the green space in cities. The coastal cities of southeast Fujian province is the most economically developed and densely populated areas of Fujian province, even in China, and also it is experiencing rapid urbanlization that has resulted in remarkable UHI effect, which will be sure to inference the regional and urban climate, environment, and socio-ecomomic development. In this study, MODIS data of July to August acquired from 2001 to 2007 in coastal cities of southeast Fujian province were elaborately selected out to retrieve the metrics of, land surface tempertuare, normalized difference vegetation index (NDVI) and albedo so as to investigate the intensity, the spatial-temporal pattern, the tendency of UHI effect, monitor annual changes and evaluate the UHI effect though urban radio index (URI) over the study period. Additionally, a new methodology and analysis techniques what was called Urban Thermal Environment Information TuPu(UTEITP) was introduced to detect and measure within-class changes of LST from the spatial, temporal and processes view, try to find the conversion mechanism and analyze the relationship between LST, albedo and NDVI qualitatively. Morever, a correlation model was built to quantitatively analyze and better understanding the relationships between LST and NDVI, LST and albedo.The results showed that UHI effect was keeping on strengthening during the whole study period with a increase tendency overall.UTEITP provided a systematic and effective way to derive comparable changes and processes. Our analysis based on UTEITP and correlation model indicates that there was a linear relationship among surface temperature, NDVI and albedo for all study years, whereas the relationship between LST and NDVI was negative, but positive correlation was shown between NDVI and albedo. These result evidence reminds us to take some instructive measures to weaken the effect of urban heat island, improve the city's thermal and habitat environment and urban sustainable development.