Research On Temperature/Pressure And Ozone Retrieval Algorithm Based On Atmospheric Infrared Ultraspectral Spectrometer

Occultation sounding has a high vertical resolution,all radiation received originated in the atmosphere and all variations in signal are due to the atmosphere.It aimed at an altitude of 10-100 km.The infrared limb sounding technique has great significance in detecting stratospheric dynamic processes and chemical processes associated with ozone.In this background,our country also actively develop occultation detection technology,planing to carry on the first Atmospheric Infrared ultraspectral Spectrometer（AIUS）.In this paper,aiming at the AIUS,we focus on the retriveval of temperature/pressure and ozone profile.By selecting the appropriate infrared band region,use the improved statistical inversion method for the inversion of temperature/pressure.use the optical estimation method for ozone profile inversion.In the temperature/pressure retrival phase,SCIATRAN is used to calculate the simulated spectra,then establish the statistical regression relationship between the sample profile and the simulated spectra.In the ozone retrival phase SCIATRAN is used to calculate the weighting function and simulated spectra,then construct the cost function between the simulated spectra and the measured spectra.By Newton iteration method to solve the cost function and get the optimal estimal solution of atmospheric ozone profile.Finally,the inversion results were compared with the ACE –FTS products.The main aspects are summarized as follows:1)Sensitivity analysis.In this paper,the SCIATRAN is used to simulate the temperature and pressure sensitivity in the broad band.The results show that the influence of temperature on the transmission is non-linear,at diferent height channels have different sensitive change.In the lower,the weak absorption CO₂ channels are sensitive to temperaturechanges.At high altitude,the strong absorption CO₂ channels are sensitive to temperature changes.The influence of pressure changes on all channels is consistent,which decreases with increasing pressure.For the ozone sensitivity analysis is similar to the temperature and pressure.In additon to the analysis of channel sensitive to O₃ itself,the sensitive of temperature,pressure,and the interference of H₂O、CO₂、N₂O are also analysized.Sensitively analysis is thefoundation of the channel selection.2)Channel selection.In this paper,I used two kinds of channel selection scheme,aiming at temperature/pressure and ozone respectively.For temperature/pressure channel selection,based on the HIRTAN database,we can get the position and intensity of the CO₂ and interference absorbtion lines.According to the channel sensitivity to temperature/pressure and interference,totally choose 120 channels for the temperature/pressure retrival.For ozone channel selection,based on channels’ Jacobian and information content,totally choose 129 channels for the ozone retrival.3)The inversion of temperature/pressure based on the dynamic statistical regression coefficient.In this paper,ues the improved eigenvector regression algorithm to retrive temperature and pressure.The inversion results were compared with the ACE –FTS products.For the temperature,the single profile inversion error is within ±5K,for the pressure,the single profile inversion error is within ±10%.Besides the limitations of the method are discussed.4)The physical inversion of ozone based on the optical estimation method.The optimal estimation method is widely used in operational inversion system.In this paper,the optimal estimation algorithm is applied to the inversion of AIUS ozone profile,and the results are compared with the ACE-FTS O₃ products.Above 60 km,the inversion result is different from that of the official product,similar to a prior.Below 60 km the difference with the official product within ±20%.Besides,reasons for the differences are analysized.