The Research On Microclimate Of Urban Fabric Based On Numerical Simulation In Shanghai

With the rapid urbanization of cities,Urban forms the complex and diverse spatial fabric structures,which are composed of different geometric interfaces.The urban form affects the microclimate environment under this structure,which leads the local climate environment different in the city and forms its own unique local climate zone(LCZ).In the background of climate change,how to ensure that urban areas can adapt to the current climate change and make appropriate improvements is an urgent problem to be solved at present.Therefore,it is particularly important to study the microclimate of different urban spatial fabric in the local area of the city.Based on the computer simulation software ENVI-met,this paper selects four urban spatial fabrics in Shanghai,e.g.Old downtown area,Gubei international community,Anting new town and New Jiangwan town,which are formed by different historical backgrounds and planning concepts,and studies the Microclimatic environmental effect of open space(open space of street network and green space)under the overall spatial pattern.Firstly,summarizing the spatial fabric characteristics by combining the historical background and planning concept of the four areas,which is the internal mechanism of forming the each spatial fabric.This paper selects different grade streets and parks in Old downtown area as the measured objects in the field,we verify the effectiveness of the software in simulating the climate environment through the measured meteorological data and ENVI-met software simulation data.The results show that ENVI-met can effectively simulate the distribution of air temperature?wind speed and relative humidity.Secondly,the paper studies the distribution of air temperature,wind speed and thermal comfort index(PMV)in the open space of street network in meso-level and micro-level in the four areas of Old downtown area,Gubei international community,Anting new town and New Jiangwan town.This paper analysis the meteorologicalfactors and thermal comfort distribution of different street grades(widths),street directions,street spacing and connectivity in the meso-level.The results show that the street temperature and PMV value of the urban main street are higher than those of the branch street and inner passage,although the ventilation of the main street is better than that of the branch street;And the microclimate effect of the south-north direction of the street is better than that of the east-west direction;The greater the street Junction spacing is,the worse the street temperature and thermal comfort is,but the better the ventilation effect of the street network is.At the microcosmic level,this paper analyzes the influence of Morphological indexes of the street fabric(Near-line Rate,Height to Wide ratio(H/W)and Sky-View-Factor(SVF)on microclimate.Firstly,this paper studies the distribution of microclimate environment under different street fabric morphological indexes in different street grades and directions,and then quantitatively analyzes the correlation between street morphological indexes and microclimatic environmental factors.The results show that the four regions have different indexes to affect the street microclimate.Generally speaking,the Near-line Rate is within the range of 0.5 to 0.8,and the higher the street H/W,the lower the value of SVF,and the best climate environment in the open space of the street.Thirdly,in the meso-level and micro-level,this paper studies the micro-climate environment of the open space of green.In the meso-level,this paper makes a brief analysis of the landscape layout of the four areas by using the landscape pattern analysis software of Fragstats4.2.And then,analyzes the distribution of microclimate factors and thermal comfort under different landscape patterns in the green open space of four areas.At the micro-level,this paper selects 19 groups of green space combinations(park green space,square green space and residential green space)of the four areas,and discusses the distribution of meteorological factors(temperature?MRT,humidity,wind speed)and thermal comfort index(PMV),and analyzes the correlation between the value of SVF and these factors.The results show thatalthough the wind speed is very small,the air temperature,MRT value and PMV value are the lowest,the relative humidity is higher,and the microclimate effect is the best in the zone of vegetation cover area dominated by arbor.Compared with lawn,the cooling effect of water cover area was more obvious,but the value of MRT and PMV was higher than that of lawn.And the cooling effect of central park green space with compound vegetation is better than that of residential green space.In the residential green space,the microclimate environment of High-rise determinant is better,the wind speed and humidity are relatively high,and the air temperature,the value of MRT and PMV are relatively small.Finally,combined with the open space of street network and green space,comprehensively analyzing the microclimatic factors and thermal comfort of open space in the four areas.The climatic and environmental effects of open space of green space in four regions are better than that of open space of street.Overall,the climate and environment effect of the Old downtown area is the worst,and the weather environment of New Jiangwan town is the best.Finally,we put forward some suggestions for improving the microclimate environment in four areas.