基于MODIS影像的PM10反演——以北京市为例

Retrieval of PM10 from MODIS Top-of-atmosphere Reflectance——A Ccase Study in Beijing

提出了一种从MODIS影像上反演可吸入颗粒物浓度(PM10)的方法。该方法的基础为从MODIS影像上反演得到的3个可见光波段气溶胶光学厚度(AOD)计算的ngstrm-α。ngstrm-α与颗粒物粒径有关,根据ngstrm-α能够得到颗粒物有效半径,进而估算颗粒物浓度。反演的气溶胶光学厚度由AERONET北京站与香河站验证。PM10反演结果由北京市环保局发布的AQI反插得到的PM10(AQI)进行验证。结果表明:从MODIS影像上反演的3个可见光波段AOD与AERONET基站AOD具有良好的相关性,相关系数为0.923,均方根误差为0.149。该方法反演的PM10与PM10(AQI)相关系数为0.794,均方根误差为48.34(μg/m3)。

Results of a new methodology for the retrieval of surface particulate matter concentration(PM10)from MODIS(MODerate resolution Imaging Spectroradiometer)top-of-atmosphere reflectance measurements in Beijing is presented in this paper.Basis of the PM10 retrieval methodology is ngstrm-α derived from multi-spectral aerosol optical depth(AOD).Based on properties of 6aerosol models from OPAC(Optical Properties of Aerosols and Clouds)database,AOD is retrieved from MODIS top-of-atmosphere reflectance at 500×500m2resolution.Particle effective radius is related to ngstrm-α and can be estimated by ngstrm-α.By integrating satellite derived AOD,effective radius and ECMWF(European Centre for Medium-Range Weather Forecasts)forecast meteorological data,therefore PM10 can be retrieved.AOD was validated by ground based AERONET measurements(Beijing and Xianghe)and PM10 was validated by surface PM10 which was estimated from AQI.The results showed that retrieved AOD(r=0.923,RMSE=0.149)and PM10(r=0.794,RMSE=48.34(μg/m3))have a good consistency with ground observations.