Himawari-8 (H8)是由日本气象厅发射的新一代静止气象卫星,可实现10 min/次的高频次对地观测,搭载的AHI (Advanced Himawari Imager)传感器设置有与MODIS暗目标气溶胶反演算法所需的类似波段.本文参考暗目标算法构建了针对该卫星传感器的陆地气溶胶反演算法:首先,通过基于地基站点观测数据的精确大气校正,统计得到短波红外与可见光波段的地表反射率比值关系,将此作为先验知识用于地一气解耦时的反射率估计;然后,初步假设大陆型气溶胶类型,利用辐射传输模型建立查找表;最后,通过模拟与卫星观测的表观反射率误差最小实现气溶胶光学厚度反演解算.选取2016年5月覆盖京津冀地区的观测数据进行测试,将反演结果与对应时间的MODIS气溶胶光学厚度产品进行对比验证,空间分布趋势一致、相关性较高,相关系数R达到0.852;通过与地基观测网AERONET站点实测数据对比验证,所有站点的相关系数R2均大于0.88,精度较高.利用反演的高时间分辨率产品,分析了京津冀地区的大气空间分布和日变化情况,结果表明:采用暗目标法对H8静止卫星陆地气溶胶光学厚度反演具有一定的潜力和可行性,能反映气溶胶的高时间变化信息,有望成为大气环境污染变化监测新的重要手段.%Himawari-8 (H8),as a new generation of geostationary meteorological satellites that observes full-disk images (images of the Earth as seen from the satellite) per 10 min,was launched by Japan Meteorological Agency to investigate aerosol characteristics.The Advanced Himawari Imager (AHI) onboard Himawari-8 has similar spectral bands with Moderate Resolution Imaging Spectroradiometer (MODIS).This study applies the Dark Target (DT) method for Aerosol Optical Depth (AOD) retrieval from AHI data.The atmospheric effect is established for the AHI data over AErosol RObotic NETwork sites.The ratio of surface reflectance between the shortwave infrared and visible bands is then obtained.This ratio serves as a priori knowledge for the surface reflectance estimation in the atmosphere-surface coupling model.Assuming that the aerosol type is continental,we build a look-up table through the radiative transfer model.With the retrieval algorithm,the AOD is determined in the case of a minimum difference between simulated apparent reflectance and satellite observations.The algorithm was used to retrieve AOD over the Beijing-Tianjing-Hebei area of China in May 2016.H8 AOD products were compared with MODIS products,and the results revealed a good spatial coincidence,with the correlation coefficient R being 0.852.The H8 AOD products were validated with AERONET observations,and they showed good linear relations,with the correlation coefficient R2 being better than 0.88.The high temporal resolution products were used to analyze aerosol spatial distribution and diurnal variation in the Beijing-Tianjin-Hebei region.Results show that H8 AOD retrieval based on the DT method has certain feasibility and potential.AOD products can express the high temporal variation of aerosol and are thus potentially useful in atmospheric environmental pollution monitoring.
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