Study On The Model Of Clear Sky Illuminance In Chongqing Based On Aerosol Optical Depth

The current architectural design is developing towards a sustainable direction,so buildings are required to be as resource-efficient as possible in the process of construction and use,and more renewable resources such as solar energy should be considered at the beginning of architectural design.Light environment is one of the main contents of architectural environment design,because artificial lighting not only consumes electricity,and long-term exposure to artificial light is not good for children’s eyesight,in contrast,natural lighting can save energy,and is conducive to both physical and mental health.Light climate refers to the average status of natural light formed by direct sunlight,scattered light from the sky and reflected light from the ground.Natural illuminance is an important part of the light climate.The traditional method of obtaining its data is through direct measurement or conversion calculation of sky brightness and radiation.Natural illuminance is not included in the routine observation items of general meteorological stations,the direct measurement data are very few,so the conversion calculation of sky brightness and radiation is still the principal method to acquire natural illuminance data traditionally.With the wide application of satellite remote sensing technology in meteorological field,a new trend of utilizing satellite remote sensing to calculate natural illumination has emerged in recent years.The advantage of satellite remote sensing is the continuity of data information in space.Under the support of the National Natural Science Foundation Project " Research on the daylight environment impact of air pollution-A case study of Chongqing",this study is devoted to the study of the impact of aerosol particles in the atmosphere on natural light.Under the support of the National Natural Science Foundation Project "Research on the impact of air pollution on natural light intensity-Taking Chongqing as an example",this study is devoted to the study of the impact of aerosol particles in the atmosphere on natural light.Theoretically,the main factors affecting the natural light intensity of the clear sky include the solar altitude angle and the atmospheric extinction.The solar altitude angle is affected by the geographical coordinates of the observation points,the number of days and the true sun time.The main substances affecting the atmospheric extinction of the clear sky are aerosols and atmospheric molecules.The scattering of aerosol to natural light is mainly meter scattering,and its forward scattering is far greater than the back scattering,so it has a great influence on illumination.The scattering of atmospheric molecules to natural light is mainly Rayleigh scattering.The degree of the scattered light in the forward direction and the reverse direction is the same,which has little influence on the illumination.The attenuation of aerosol to natural light can be expressed by AOD,which can be obtained by satellite remote sensing.The main purpose of this paper is to study the relationship between AOD of aerosol optical thickness and outdoor natural illuminance under the condition of clear sky,and to establish AOD illuminance model.Because satellite remote sensing can only get AOD data when there is no cloud or thin cloud(the influence of thin cloud on AOD data can be eliminated by cloud removal processing in case of a small amount of cloud),the clear sky in this study refers to the sky condition that can get effective satellite remote sensing AOD data.In this study,the influence of the surrounding environment on the natural illuminance is not considered.Therefore,the illuminance in this paper refers to the total illuminance of the natural light on the outdoor unobstructed horizontal planeThe main research contents are as follows:(1)MODIS McD19-a2 products were calibrated with foundation CE318 sun photometer,so that the accuracy of MODIS AOD data could meet the requirement of basic data modeling.(2)Based on the influence factors of clear sky illumination,sinH,the sine value of solar altitude Angle,and W,the atmospheric precipitation content,were selected as the correction factors,and together with AOD,they constituted the clear sky illumination model of Chongqing.(3)The established model was used to invert the annual sunny illumination value of11 stations in Chongqing,and by means of spatial interpolation,the distribution map of annual,seasonal and monthly illumination in the sky in Chongqing was obtained.Through analysis,the annual clear sky illuminance shows distinct seasonality,summer illuminance is significantly higher than winter illuminance,and the difference of the city’s clear sky illuminance in winter is greater than that in summer;Meanwhile,the distribution of sunny sky illumination also has certain regional features,there are two obvious high value areas in Jiangjin and Wan County(now Wanzhou).This model can be applied to the building lighting simulation in the following research,to explore the influence of outdoor illumination on indoor illumination in sunny days and the reasonable utilization of natural light.