| Ozone(O3),a trace gas with unstable chemical properties,has low concentration in the atmosphere.It is mainly distributed in the stratosphere(90%)and troposphere(10%).Ozone absorbs a huge amount of ultraviolet radiation in the stratosphere and maintains the temperature structure of the stratosphere.In the troposphere,ozone mainly comes from the atmosphere photochemical reactions between atmospheric components.Ozone is a kind of"harmful"gas near the ground,which causes damage to human beings and other animals and plants.Using satellite remote sensing to detect the concentration distribution of ozone on a global scale has great significance for the study of atmospheric dynamics and global climate change.Presently,satellite remote sensing detect ozone by nadir viewing,occulation observing and limb sounding.Atmospheric Infrared Ultraspectral Sounder(AIUS)is an infrared occultation spectrometer onboard the Chinese Gao Fen-5 satellite,which is designed to detect the concentration distribution and chemical process of ozone and other atmospheric components.Based on the detection characteristics and the spectral of GF-5/AIUS,the retrieval algorithm and the validation of ozone profile are discussed in this paper.(1)Band selection and spectral quality analysis.Firstly,the retrieval microwindows of the ozone are selected base on the information entropy iterative method of Jacobian matrix.Then the quality of AIUS spectral data are analyzed in the selected microwindows.Finally,eight microwindows with high quality are picked out,which can improve the retrieval efficiency.(2)Establishment of prior knowledge database.The products of ACE-FTS and MLS in recent years are divided into 5°latitude×30°longitude grids by month,and a fine atmospheric background database is established to approximate the real atmospheric state in this paper.At the same time,MLS ozone profile products are used to build the prior profile database of ozone,which can match the actual AIUS data by time and position during the retrieval process to provide accurate prior profile.(3)Tangent height correction.Using the strong absorption of nitrogen in2490-2520cm-1and ozone in 1020-1150cm-1,a method of lookup table of simulated transmittance is proposed in this paper.The lookup table provides accurate height information for retrieval process.It has been proved that the altitude of AIUS can be obtained accurately by the method,and the correction efficiency is improved by27.33 times.(4)Retrieval algorithm.Based on the optimal estimation method,the constraint factors?is calculated by the analysis of AIUS spectral.The constraint factors?is updated in each iteration,which improves the calculation of the OEM in the AIUS ozone profile retrieval.(5)Design and implementation of AIUS ozone profile inversion software.Based on the retrieval algorithm of the ozone profile,a AIUS ozone profile inversion software is designed and implemented in this paper.The software meets the functional requirements of the ground management system of GF-5 satellite data,and can be used for business production of ozone profile products.(6)Validation of AIUS retrieval experiments.Based on the AIUS ozone profile inversion software established in this paper,8-track AIUS data from December 2018to January 2019 are selected to retrieve the ozone profile.The retrieval profiles are compared with MLS ozone products.It shows that the relative difference between the retrieval results of AIUS ozone profile and MLS ozone profile products is within10%at 20?50km.The relative difference is over 20%at 10?15km and 70?90km.The peak value of the average kernel function of the retrieval results are close to 1and the degree of freedom is high,which shows the retrieval results are reliable.The validation research shows that the AIUS ozone profile products with high accuracy can be obtained by the inversion software.Therefore,The AIUS observation data can be used to described the vertical distribution of ozone concentration the middle and upper stratosphere. |
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