Application Of Atmospheric Effect Modification In GB-SAR Deformation Monitoring

Geometric characteristics of targets can be measured by deformation monitoring,which has important significance for monitoring and forecasting of natural disasters landslides,rockfall,debris flow etc..GB-SAR is one of the most important technologies in the field of deformation monitoring,which has high accuracy,non-contact measurement,high spatial and temporal resolution,obtaining abundant information and other characteristics.But in the actual application,GB-SAR measurement is vulnerable to outside interference,especially in complex regional meteorological environment,the phase error of atmospheric effects severely affect the measurement accuracy,to solve this problem,this paper focuses on the research of atmospheric effects in GB-SAR deformation monitoring,the main contents are:(1)On the basis of expounding the principle of GB-SAR interferometer and the essence of atmospheric effect,the formula of electromagnetic wave refractive index and GB-SAR interferometer are used to calculate the deformation,when the distance is 200m and the atmospheric refractive index of the electromagnetic wave changes to 10-5 level,the error caused by the atmospheric effect is millimeter,and the atmospheric effect error increases rapidly with the increase of atmospheric refractive index change.The experiment also analyzed the relationship between the refractive index and the air pressure and humidity when the temperature is-20?,0?,20? and 40?,and the relationship between the refractive index and temperature and humidity when the pressure is 800hPa,900hPa,1000hPa and 1100hPa.The results show that the effects of humidity on the atmospheric refractive index is greater than the temperature and pressure;when the temperature below zero,no significant change of refractive index change;above zero,with the increase of temperature,its influence increases gradually;the pressure changes have little effect on atmospheric refractive index.(2)Using L observation model and observation S model of IBIS system to do the atmospheric effect experiment,analysis the atmospheric effects which were observed in targets with different observation distances in the two measuring modes,and try to use the meteorological data to correct the atmospheric effect error in the S model.The results show that the atmospheric effect has obvious spatial and temporal features;the longer the observation period is,the greater the influence of atmospheric effect is,the farther the distance is,the larger the atmospheric effect error is;and it is feasible to use the high spatial and temporal resolution meteorological data to compensate the atmosphere effect.(3)The deformation monitoring experiment on the east side of L i anz i ya was carried out to verify the practical application of GB-SAR deformation monitoring.In order to solve the influence of atmospheric effect in measurement,a method based on atmospheric refractive index profile is presented,this method takes into account the vertical variation of atmospheric refractive index,which is more suitable for the change of meteorological environment.Through coordinate transformation,target recognition and meteorological data preprocessing process,the correction method of the traditional fixed control point,the fixed point correction method based on the atmospheric refractivity profile model and the correction method of meteorological data are used to correct the atmospheric effect error.The results show that the correction method based on the atmospheric refractive index profile model can effectively reduce the atmospheric effect,the precision is up to millimeter,and the correction effect is better than IBIS software and meteorological data correction method,the method is suitable for monitoring the deformation in high mountain and gorge area.In this paper,different wavelet basis functions are used to filter the measurement results,the results show that the wavelet denoising can effectively eliminate the random error in the measurement data,and play a better filtering effect,which is conducive to GB-SAR data processing and analysis of the results.