Research On Wind Field Retrieval Technology Of Spaceborne Doppler Asymmetric Spatical Heterodyne Interferometer

The wind field information of the thermospheric atmosphere in the altitude range of 80-300 km is the basic data for studying the atmospheric dynamic process,the distribution of matter and energy,and the spatial and temporal changes in the region.Doppler asymmetric spatial heterodyne(DASH)interferometer is a newly developed passive wind measurement interferometric spectroscopy in recent years.Its simple structure,high throughput,and simultaneous measurement of multiple spectral lines make it very suitable for spaceborne wind measurements.Stable and high-precision inversion technology is very important for wind field detection of spaceborne DASH interferometer.Relevant research abroad has established a complete wind field inversion technology system for spaceborne DASH interferometer,but there is still room for optimization in terms of inversion accuracy and stability.According to the spatial modulation principle of its optical path difference,it is feasible to optimize from the directions of image preprocessing and correction,phase and profile inversion methods,instrument drift monitoring and calibration,etc.Related researches have also been carried out in China on image preprocessing,phase inversion error analysis and optimization,etc.In this dissertation,aiming at improving the accuracy and stability of the wind field inversion of the spaceborne DASH interferometer,relevant research has been carried out in the key links of the inversion technology.The main work are as follows:1.Research on detection principle of thermospheric wind field by spaceborne DASH interferometer.Firstly,by analyzing the distribution of optical path difference on the image plane of the interferometer,the theoretical expressions of the interference fringes under the two incident conditions of on-axis light and off-axis light are calculated respectively.The expression of the phase term in some previous literatures is corrected.The decisive effect of the incident light wavenumber on the interference phase is proved,and the theory is verified by optical simulation and grating moving experiment.Then combined with the limb observation mode,the forward simulation model of wind measurement by spaceborne DASH interferometer is established.2.Research on phase inversion technology of DASH interferometer.In this dissertation,the basic method of DASH phase inversion is established,including image preprocessing,phase inversion,phase thermal drift monitoring and correction,etc.Among them,in terms of image preprocessing,a data baseline correction method based on envelope extraction combined with polynomial fitting has been developed,which can achieve less than 0.5% low-frequency baseline energy residue in the correction of measured data.An interferometric image tilt detection method based on phase inversion has been developed.Compared with the detection error based on the Hough transform method through simulation,under the same signal-to-noise ratio,the accuracy of the method based on phase inversion is improved by more than 10 times.In terms of phase thermal drift monitoring,the method flow of imaging thermal drift monitoring based on segmented edge fitting was developed,and the experimental verification was carried out and the monitoring accuracy was analyzed through simulation.When the data SNR ratio is higher than 35 times,the method can reach an accuracy of 0.05 pixel,and the corresponding wind speed in the experimental prototype is about 12 m/s.Afterwards,a phase inversion technology verification was carried out based on a DASH prototype for thermospheric wind field detection.The prototype continuously observes at night.The overall average wind speed at different times in the observation period is obtained through phase inversion,and compared with the average wind speed in the observation period calculated according to the HWM14(Horizontal neutral Wind Model 14)model.The effectiveness of the phase inversion method is verified by the comparison of wind speed results.The two groups of meridional wind and zonal wind maintained high consistency in value and trend,with correlation coefficients of 0.80 and 0.77,respectively.3.Research on wind profile retrieval technology of spaceborne DASH interferometer.The principles and methods of wind profile inversion based on global optimization and ‘onion peeling’ are analyzed,and the advantages and disadvantages of the two methods are compared.Then,the DASH interferometer forward images of the oxygen red line and the green line were respectively used to invert the wind speed profile using the ‘onion peeling’ method.After adding Gaussian noise with a signal power of 1/200,the standard deviation of the wind speed profile inversion error is about5 m/s,which verifies the effectiveness of the inversion method.The ‘onion peeling’method was used to establish a profile inversion software system,and the on-board data of MIGHTI(Michelson interferometer for global high-resolution thermospheric imaging)was used to conduct profile inversion experiments.Compared with MIGHTI data products,the numerical and There is a good consistency in the trend,which verifies the effectiveness of the inversion system.In this dissertation,based on the research and work on basic interference theory,phase and profile inversion technology of DASH interferometer,a full-link forward and inversion model of thermospheric wind field detection by spaceborne DASH interferometer is established.Among them,innovative progress has been made in determining the accurate expression of the phase of the DASH interferometer,improving the baseline and image tilt detection and correction effects in image preprocessing,and imaging thermal drift monitoring and correction.It provides a reference for higher accuracy and more stable wind field inversion.