陆地生态系统碳监测卫星多角度偏振成像仪细粒子气溶胶反演

Retrieval of fine-mode aerosol based on Directional Polarimetric Camera onboard Terrestrial Ecosystem Carbon Inventory Satellite

细粒子气溶胶光学厚度是大气环境监测、气候变化评估所需的关键参数。对2022年8月发射的陆地生态系统碳监测卫星(CM-1)上搭载的多角度偏振成像仪(DPC)进行了较为系统的介绍。DPC/CM-1的主要改进是星下点空间分辨率从3.3 km提升到2.4 km。针对DPC/CM-1载荷及数据特点,发展了基于偏振与光谱特征和空间纹理特征的云检测方法,同时耦合了多角度信息实现较严格的云像元判识。该方法对于沙漠、植被、丘陵,以及海表耀光及非耀光区域等不同下垫面,均有较好的检测效果。发展了基于改进气溶胶模型的细粒子气溶胶光学厚度(FAOD)反演算法,利用全球地基气溶胶观测网(AERONET)数据对FAOD反演结果进行了验证,拟合直线斜率达到0.95以上,且有接近73%的数据分布于期望误差以内,说明了反演算法的可靠性。FAOD反演结果清晰显示出全球FAOD空间分布特征,其中,印度、非洲中部等地区受人口分布、工/农业排放、生物质燃烧等影响,FAOD高值达到0.7~0.9。DPC/CM-1在轨测试期间的初步反演结果表明其在大气环境监测、污染传输分析等方面的潜力,能够提供更精细尺度的大气参数反演结果。

Fine-mode aerosol optical depth is a key parameter required for atmospheric environment monitoring and climate change assessment.Directional Polarimetric Camera(DPC)onboard the Terrestrial Ecosystem Carbon Inventory Satellite(CM-1)launched in August 2022 was systematically introduced.A major improvement of DPC/CM-1 over other DPC sensors is that the nadir spatial resolution increased from 3.3 km to 2.4 km.According to the sensor and data characteristics of DPC/CM-1,a cloud detection method based on polarimetric and spectral/spatial texture characteristics was developed,and the multi-angle observation was coupled to achieve strict cloud pixel identification.The results of DPC/CM-1 cloud detection show that this method has good detection effect for bright surface such as desert areas,dark surface such as vegetation and hill areas,and the sun-glint and non-sun-glint areas over ocean.An improved fine-mode aerosol optical depth(FAOD)retrieval algorithm was developed.The FAOD retrievals were verified by the data of Aerosol Robotic Network.The validation results show that the slope of the fitted line reaches more than 0.95,and nearly 73%of the observed data are distributed within the expected error,indicating the reliability of the retrieval algorithm.The retrieval results of FAOD clearly show the spatial distribution characteristics of global FAOD.The high FAOD regions(reaching 0.7-0.9)mainly include India and Central Africa,where the high fine particle aerosol contents are probably due to the dense population distribution,strong industrial/agricultural emissions and biomass combustion.The preliminary retrieval results of DPC/CM-1 during the in-orbit test phase show its potential for atmospheric environment monitoring and pollution transport analysis,especially when combined with its high spatial resolution,providing fine-scale atmospheric parameter retrieval results.