Study On Thermal Environmental Effects Of Urban Landscape Pattern Changes In Chengdu

At present, with the rapid development of urbanization and global warming, the urban heat island effect is more and more serious, which has intensified the thermal effect of the city, and the urban thermal environment is becoming more and more serious. Urban thermal environment resultsfrommany factorssuch asthe urban landscape pattern, urban anthropogenic heat, climate conditions and so on. With the acceleration of urbanization process, the urban surfacelandscape changes. Based on thenaturalsurface is continuouslysubstitutedbyurban artificialsurface, heatstorageandheattransfer changed, and the urban thermal flux changed. The change of urban landscape pattern has a very important impact on urban thermal environment.It is significant to study the change of urban landscape pattern and its influence on urban thermal environment, which is of great significance to the development of regional ecological security and urban health.Chengdu is a science and technology center, trade center, financial center and traffic center in Southwest. Chengdu also is the center city of politics, economy and culture in the southwest. Due to the rapid development of Chengdu City and the rapid development of urban construction and transformation, the thermal environment problems gradually exposed.This paper,selecting Chengdu asanexamplearea, extracturban surface information, and retrievelandsurfacetemperaturefromremotesensingimages.Baseonremotesensing, geographic information systemandspatialstatistic methods, this paper analyzed theimpervious surfacesspatial pattern and thermalenvironmentspatial pattern, andlearned the relationship between urban surface landscape and the thermal environment. Themainresearchworksareasfollows:(1)In this paper, the effect of the NDISI method and the BUAI method on the extraction of impervious surface is compared and analyzed, and impervious surface is successfully extracted. Study found that although the NDISI method is not affected by cloud cover, but the extraction accuracy than BUAI method.(2)The surface temperature of Chengdu was retrieved by using the MW method, and compared with the actual temperature of the weather station.The retrieved surface temperature is close to the measured temperature, and the accuracy is better.(3)Spatial and temporal characteristics of impervious surface were analyzed in Chengdu. The impervious surface of the first circle within the administrative regionis significantly more than the second circle. Impervious surface presents a main, multi point distribution pattern in Chengdu, and is mainly distributed in central urban area, surrounding counties, industrial parks and industrial parks.With the development of the city, the impervious surface is increasing, and the expansion of the West and the south is obvious.(4)Spatial and temporal characteristics of thermal environmentwere analyzed in Chengdu. The difference between the average surface temperature of the first circlewithin the administrative regionand the average surface temperature of the second circle is becoming more and more obvious. thermalenvironment presents a main, multi point distribution pattern in Chengdu, and it gradually decreases from the center of the high temperature zone. High temperature zone and sub high temperature area increased, and the southwest and northwest temperature trend contiguous patches.(5)The relationship between the urban landscape pattern and the thermal environment in Chengdu city is discussed.Impervious surface and the surface temperature were positively correlated. Increasing urban impervious surface significantly accelerated the environmental effects of urban heat. Vegetation negatively related with the surface temperature. Increasing urban vegetation can reduce the urban thermal environment effect. The relationship between water and surface temperature is weak.