Study On Upper Atmospheric Wind Field Based On GBAII-SHS

The observation on the middle and upper(60-300 kilometers)atmosphere temperature and wind speed has become a frontier research in recent years.Our group has been developed a prototype of GABII(Ground based airglow imaging interferometer)to detect the temperature and wind speed at 90-100 km in 2011.The GBAII combined a Fabry-Perot interferometer(FPI)with a wide-angle Michelson interferometer(MI),but the accuracy of wind speed measurement is still need to be improved.The interference pattern of GBAII is circular ring,but the CCD detector is square.so,the wind speed inversion process is complex.In order to improve the measurement accuracy of wind speed and obtain straight interference fringe at CCD detector,in this research,we replace the MI reflector of GBAII with reflection grating to build GBAII-SHS(Spatial Heterodyne Spectroscopy).We ultimately select a line emitted from O(1S)band at 98 km with wavelength of 557.7 nm as the source.The principle of wind speed measurement is studied in detail.The reflection angle(Littrow angle)of reflection grating is 14.3 degrees with 900 line grating grooves.The optical system of GBAII-SHS is designed.Using the optical software ZEMAX,we obtain the 3D structure diagram of the optical system.The detection spectrum range of interference fringes on the array CCD are 17930.7～18181.2cm-1,and the maximum resolution is about 0.982cm-1.The forward model is studied.We use the MATLAB to calculate the forward model equation and the number of interference fringes is 15.The wind speed of 50m/s is imported into ZEMAX for simulation,the interferometry graph is brought into MATLAB for data inversion and fitting,and the phase difference is 0.191 rad,and finally the wind speed solution formula is introduced to the inversion wind speed of 57.88m/s,and the wind speed accuracy is 7.88 m/s.The GBAII-SHS system is set up our laboratory.The imaging interferogram of 557.7 nm airglow is simulated by 532 nm laser source.The straight fringes confirm the GBAII-SHS working well,which can be used to detect wind speed at 98 km.Since the novel coronavirus pandemic,we cannot carry out field observation,this will be the task of the research group to continue to complete.