Research On Surface UV-B Irradiance Algorithm Of Spaceborne Trace Gas Differential Absorption Spectrometer

Solar radiation has a wide range of effects on life on the earth,providing energy for the Earth's atmospheric motion.In the process of modern industrialization,human activities have caused significant changes in the atmospheric system,such as the decrease of stratospheric ozone amount,the appearance of ozone holes,and the compound pollution of the tropospheric atmosphere,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.The monitoring of surface UV-B irradiance on the ground has shortcomings such as sparse site distribution and short running time.Compared with the limited ground-based monitoring,satellite remote sensing technology can realize long-term monitoring of global surface UV-B irradiance,so satellite monitoring has become an increasingly important way to monitor surface UV-B irradiance.In this dissertation,based on the atmospheric trace gas differential absorption spectrometer(EMI)carried by domestic Gaofen-5 satellite,we carried out the algorithm study of EMI surface UV-B irradiance using the data from EMI inversion and observation,completed the construction of EMI surface UV-B irradiance algorithm,and realized the preliminary inversion of EMI global surface UV-B irradiance.In this dissertation,the SCIATRAN model is used to establish surface UV-B irradiance look-up table under clear-sky conditions,using the solar zenith angle,surface albedo,altitude and total ozone data corresponding to each pixel of EMI,and multi-dimensional interpolation to calculate the clear sky surface UV-B irradiance.In order to reduce the time spent on the construction of the lookup table and the interpolation lookup,the SCIATRAN model was used to analyze the sensitivity of the factors affecting the surface UV-B irradiance.Based on the sensitivity analysis results of the surface UV-B irradiance,the input parameter node of the clear sky surface UV-B irradiance look-up table is reasonably determined,and the surface UV-B irradiance under the EMI clear sky pixel is calculated.Then,the research of the correction method under cloud and aerosol scenes was carried out.The cloud correction method based on Lambertian equivalent reflectance and the aerosol correction method based on aerosol index are used to realize the correction of surface UV-B irradiance under clear-sky conditions and obtain surface UV-B irradiance under actual conditions,completing the inversion of global surface UV-B irradiance.Finally,in order 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 under the same time using the method of statistical distribution and linear fitting.The correlation coefficient with the OMI data was greater than 0.90,and the correlation coefficient with the WOUDC site data was greater than 0.91.The correlation coefficients of both indicate that the results of this 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 higher accuracy in the region with low surface albedo;while the results are large in the region with high surface albedo.Overall,the surface UV-B irradiance products of EMI are highly accurate,which can provide a research basis for the subsequent release of surface UV-B irradiance and other related products.It also proves the load's ability to monitor the spatiotemporal distribution of surface ultraviolet radiation and provides a basis for long-term monitoring of the spatiotemporal changes of surface UV-B irradiance.