地表UV-B辐照度会对地球生态系统产生非常重要的影响。利用卫星遥感探测，可实现全球地表UV-B辐照度的长期探测，对于生态系统评估和大气科学研究等具有重要意义。目前基于国产卫星的地表UV-B辐照度产品较少，因此本文开展了高分五号卫星大气痕量气体差分吸收光谱仪（EMI）的地表UV-B辐照度的初步反演。首先基于地表UV-B辐照度的敏感性分析结果，建立无气溶胶情况下晴空地表UV-B辐照度查找表，随后提出了云、气溶胶场景下的校正方法，实现了全球地表UV-B辐照度的反演。最后，为验证该算法的准确性，将EMI结果分别与欧洲OMI卫星数据、WOUDC地面站点数据进行了对比，其中与OMI数据的相关系数大于0.9，与WOUDC地面站点数据的相关系数达到0.97。研究结果表明EMI载荷的地表UV-B辐照度产品准确性高，为后续地表UV-B辐照度等相关产品的发布提供研究基础，也证明了该载荷在全球地表紫外辐射时空分布监测应用中的能力。

Surface UV-B irradiance can have a very important impact on the Earth"s ecosystem. In the modern industrialization process, human activities have led to significant changes in the atmospheric system, such as the reduction of stratospheric ozone, the emergence of ozone holes, tropospheric atmospheric composite pollution and other phenomena, and the corresponding changes in global surface UV-B irradiance, which have brought significant impacts on human and ecological environment, such as skin cancer and crop yield reduction. Therefore, it is important to monitor the surface UV-B irradiance. There are two main ways to monitor surface UV-B irradiance: ground-based monitoring and satellite monitoring. Ground-based platform surface UV-B irradiance monitoring has disadvantages such as sparse site distribution and short operation time. Compared with the limited ground-based monitoring, satellite remote sensing technology can realize the long-term monitoring of global surface UV-B irradiance, which is important for ecosystem assessment and atmospheric science research, etc. At present, there are few surface UV-B irradiance products based on domestic satellites, so the preliminary inversion of surface UV-B irradiance from environmental trace gas monitoring instrument(EMI) on the Gaofen-5 satellite is carried out in this paper. Firstly, a sensitivity analysis of the factors influencing surface UV-B irradiance was performed using the SCIATRAN model to reduce the time consumed in constructing the look-up table construction and interpolation look-up. Based on the results of sensitivity analysis of surface UV-B irradiance, the input parameter nodes of the clear-sky surface UV-B irradiance lookup table are reasonably determined, and the surface UV-B irradiance of EMI under clear-sky conditions is calculated. Then, the research on the correction methods in the presence of clouds and aerosol scenarios was carried out, and the correction of surface UV-B irradiance under clear sky conditions was realized by the cloud correction method based on Lambert equivalent reflectance and the aerosol correction method based on aerosol index to obtain the surface UV-B irradiance under actual conditions, and the inversion of global surface UV-B irradiance was completed. Finally, to verify the correctness of the EMI surface UV-B irradiance algorithm, the results of the algorithm were compared with the European OMI satellite data and WOUDC site data at the same time using a linear fitting method, where the correlation coefficient R with the OMI data was greater than 0.9, and the correlation coefficient R with the WOUDC site data reached more than 0.91, both of which indicate that the results of the method are in high agreement with the OMI data and WOUDC data. However, there are still some shortcomings. The surface UV-B irradiance inversion algorithm of EMI has high accuracy in the region with low surface albedo; while the results are large in the region with high surface albedo. The results show that surface UV-B irradiance products of EMI are highly accurate and can provide a research basis for subsequent releases of surface UV-B irradiance and other related products. These also demonstrate the payload"s capability in global surface UV radiation spatial and temporal distribution monitoring applications, providing a basis for long-term monitoring of the spatial and temporal variation of surface UV-B irradiance studies.