Study On The Distribution Patterns And Predictive Model Of Solar Radiation In Urban Street Canyon Based On Panoramic Images

Solar radiation is the main driving force for adjusting the urban climate and the heat balance of street canyon,and it is also an important parameter affecting the thermal and humid environment outside buildings.Understanding the distribution law of urban solar radiation is helpful for us to deal with the existing urban environmental problems and make a prediction of problems in advance.The urban form under the artificial planning influences the distribution law of urban climate and solar radiation in the city and makes it different from other areas.Among them,the SVF(Sky View Factor)is one of the most discussed relevant parameters.Existing research of urban solar radiation distribution mostly produced in the developed high-density urban area,and low-density urban areas are disscessed less.Most of inland China is low density areas,and the solar radiation data of meteorological stations is relatively scarce.Most of cities have only one distant meteorological stations for one or servel cities.Thus it is important to combine the meteorological data with urban form to extend a single station data to the whole city.This study aims to explore the distribution law of solar radiation in urban street street canyon.Based on the existing solar radiation predictive model and batch to obtain and calculate basic data,the optimization and verification of predictive model and the effect of urban form to distribution of solar radiation are produced.The main contents are as follows:(1)Based on the literature of daily total solar radiation predictive model,sorting out the two model.One is based on daily data and other is based on hourly data.Besides these two model,another model with reflection radiation is used to optimize these two.The filed experiment is conduced to verify the accuracy of the optimized model and chose hourly model to investigate the solar radiation in urban area.(2)Since the huge amount of urban data,the calculation process of obtaining the total solar radiation of urban street canyons in batches by python was developed,and the total daily solar radiation distribution of Xi 'an(within the high-speed around the city)was obtained by this method.(3)Taking the Ming city,a typical middle and low-density old urban area in Xi 'an,as an example,the influence of the direction and width of street canyons on the distribution law of solar radiation was studied.The influence law of street canyons morphology on the relationship between SVF and solar radiation was obtained.The results show that different street canyons and solar positions have different effects on SVF and solar radiation intensity: with the change of street canyons width,the radiation intensity changes in different in different direction of street canyons.The influence of the width of south-north street canyons on the radiation intensity is obviously smaller than that of east-west street canyons.Except the summer solstice day(the highest angle of the sun),the mean difference between the widths of the east-west canyons was greater than that of the south-north canyons.The correlation between SVF and solar radiation intensity is related to the direction and width of the street canyon.The correlation in east-west direction canyon is smaller than in the north-south direction,and in the wider street canyon is larger than in the narrow street canyon.In the east-west street canyon,the relationship between SVF and solar radiation intensity is more easily affected by the width of the street canyon.The narrower the street canyon,the greater the influence of SVF on solar radiation intensity(except in winter).(4)The distribution of basic parameters of Xi' an urban form(floor area ratio,building density,building average height,etc.)is obtained and analyzed,and the basic distribution law is studied.Combined with the calculation results of solar radiation,the solar radiation distribution law of the street canyon in the main urban area of Xi 'an city(within the expressway around the city)is studied.The results showed that the relationship between the floor area ratio and solar radiation was the most conspicuous,showing a negative correlation.The narrower the street canyon,the stronger the influence was.In the east-west street canyon,the change of floor area ratio on the south side had a stronger influence on the radiation intensity than that on the north side.The influence of building density and average building height on solar radiation also presents a certain rule,but in some cases the correlation is too low.Therefore,when using urban morphology parameters to predict solar radiation intensity,floor area ratio can be taken as the main reference value,and building density and average building height as auxiliary reference.