Remote Sensing Research Of Green Space Evolution And Its Cool Island Intensity

Constantly expanding of the city at the same time,also with its underlaying surface properties of changing trend from natural surface to impervious surface,and caused one of main ecological environment problem is the Rising of urban heat island. And then,the urban green space plays a positive role in reducing urban thermal environment. Therefore,further study of coupling relationship between space layout of urban green space and thermal environment,it will have great importance to reasonable planning and layout of urban green space and reducing thermal environment.Therefore, this article choose megacity in north China-Tianjin as empirical research object,based on remote sensing and geographic information system software platform and statistical analysis related mathematical methods.from the urban green space layout and evolution characteristics,mainly discussed the coupling relationship between green space and cold island effect,and then build tianjin urban climate map on the basis of analyzing urban cold island landscape evolution characteristics, and put forward the corresponding suggestions and strategys for green space planning and layout etc.First of all, this thesis analyzed urban green space and its evolution characteristics of landscape pattern in tianjin,and from remote sensing images based on four years of 1992, 1999, 2006 and 2013, to interpretation,dynamic analysis and statistical findings:The area of green space is declining more obvious in Tianjin for recent 20 years,the farmland area is the largest decline,mainly change to green land and construction land types,reduce nearly 20km2. Change rate of green space began to increase rapidly in 2006.On the number of landscape patches showed increasing trend,with the fastest growth in 1999-2006. Patch density at the city edge has rapid increase since 1999,the patches shape of green space is more and more complex and presents irregular trend,polymerization degree index has declined after 2006,and landscape fragmentation phenomenon bacome more serious.Secondly, the main goal and key content of this study is coupling analysis between urban green space and its cold island effect. Studied on angles from landscape pattern characteristics, vegetation coverage and morphological characteristics:for landscape perspective, cold island effect of three types from green space mainly by its neighboring patches number,it has a significant influence on surface temperature changes of the type and location for green space. The more concentrated of spatial distribution for green space type,the cold island effect is more significant. 10% increasing of concentration will drop 0.33℃. Largest patch index was significantly negative correlation with average temperature. 10% increase will drop 0.34℃.10% increase of fragmentation index will increase 0.72℃ for average surface temperature;For vegetation perspective,the related parameters of vegetation coverage and cold island intensity is linear positive correlation,10% increase of vegetation coverage can drop about 0.33℃;From the form,through analysis of green space in seven different cold island intensity characteristics form,and then summarizes distribution characteristics of cold island effect strength and less for green space, constructed the form type of cold island effect model; For characteristics of cold island effect,the influence of the most important factors are park area and vegetation coverage,which affects the park land surface temperature. Water ratio in the park also affects the surface temperature to a great extent,cooling intensity for water is higher than 30% and vegetation coverage is higher than 10 is more significant in the park.Thirdly,it’s on the deep analysis from four aspects about the evolution of annual and season,cold island profile and influencing factors. For interannual evolution,higher temperature plaques plays a leading role on surface temperature evolution in study area,the largest plaque index segmentalized trend since 2006. The average patch area of high temperature expands ceasingly, spread index and fragmentation index increase in 2006-2013. The temperature of every patch types showed gradually evenly distributed trend,the intensity of urban cold island effect began to slightly increase after 2006;For seasonal evolution,after entering winter plaque area is rapidly increasing,patch number of low temperature plaque shift to high temperature from spring to summer,summer to autumn,medium temperature and above plaque shift to lower temperature,spring to summer,the biggest plaque index have most serious fall,low temperature plaque index began to increase since winter. The surface temperature plaque has largest spread degrees in summer. Urban cold island intensity in winter is highest;For cold island profile characteristics,the ground temperature on the changes in peak and valley value in study area,the green space is less than the temperature of water,but its further cooling distance. The cool island intensity for different types of green space are different;On the influence factors of cold island pattern,including the size of vegetation coverage,types of underlying surface characteristics,city layout and adjustment,etc. In addition,the natural factors such as wind,cloud cover and relative humidity,and human factors such as urban area,the trend of street,population density all affect the pattern distribution of urban cold island to some extent.Finally,it’s about the green space planning based on urban green space and cold heat island distribution.Through to establish the Tianjin urban climate map, and then divided into five urban climate planning partition,formulate the corresponding partition planning advice specifically from macro and micro level for each planning division. At the same time, definite the heat loads distribution and urban climate sensitive area in Tianjin, and put forward relative optimization measures based above. Finally planning the cooling channels combined with distribution of green space,and put forward the planning direction for urban green space.This paper constructed comprehensive quantitative research methods of perspective and methods based on green space evolution and its cold island effect on the theoretical research level in city scale. For empirical applications, through serious discussion on layout structure, evolution characteristics, cold island effect and planning advice of urban green space in Tianjin, it can provide technical support for urban green space planning and residential environment construction in Tianjin,and provide case reference for the similar research and planning practice.