CN-121578302-B - InSAR (interferometric synthetic aperture radar) atmospheric delay phase correction method for weighted resampling along ground distance

Abstract

The invention discloses an InSAR atmospheric delay phase correction method for earth distance weighting resampling, which comprises the steps of S1, obtaining two-scene SAR image subsets covering a research area and obtaining two-scene clean water vapor data, S2, carrying out differential interference processing on the two-scene SAR image subsets covering the research area to obtain differential interference phases, S3, accurately calculating the atmospheric delay phases by using an atmospheric delay phase correction model, and S4, accurately solving the deformation of the earth surface in the radar sight direction. The invention provides the latest weight value of each pixel of the ground on the zenith path delay difference in the ground slope direction by correcting the sampling mode of the water vapor product along the ground slope direction, and finally provides the accurate and efficient slope-direction phase total delay calculation method along the ground slope, thereby further optimizing and improving the repeated orbit synthetic aperture radar differential interferometry method, leading the measurement result to be more scientific and reasonable, and having wide application prospect in the repeated orbit InSAR atmospheric phase correction field.

Inventors

• ZHU JIE
• SHI HONGBO
• HAN YUFEI
• LI YU

Assignees

• 中国地震台网中心

Dates

Publication Date

20260508

Application Date

20251218

Claims (3)

1. 1. An InSAR atmospheric delay phase correction method for weighted resampling along the ground distance is characterized by comprising the following steps: s1, performing multi-view and clipping treatment on synthetic aperture radar SAR images of two scenes and the same orbit to obtain two scene SAR image subsets covering a research area, clipping near infrared precipitable vapor products according to the position of the research area, and further removing and filling cloud pollution pixels in the precipitable vapor products to obtain two scene clean vapor data; S2, carrying out differential interference processing on the two-scene SAR image subsets covering the research region to obtain differential interference phases And the differential interference phase Including atmospheric delay phase errors; s3, according to the acquired two-scene water vapor data, using an atmospheric delay phase correction model to accurately calculate an atmospheric delay phase caused by the difference of atmospheric conditions during the observation of the two-scene SAR images ; Specifically, the method comprises the following steps: S31, calculating zenith humidity delay, namely converting the precipitable water vapor into zenith humidity delay ZWD by using a surface temperature measurement method according to a near infrared water vapor product PWV provided by a space radiometer: Wherein, the Is a dimensionless conversion factor, and has a value of 6.0 to 6.5; indicating the density of the water in the liquid state, And Respectively represents the universal water vapor constant and the molar mass of water vapor; And Is the atmospheric reflectance constant; Represents the average atmospheric temperature of the troposphere; S32, calculating a zenith wet delay difference map ZPDDM: Wherein, the And The imaging times of the PWV are shown separately for the two times, Representation of The time of day is the delay of the top wet, Representation of Time zenith wet delay; s33, considering that the water vapor product sampling is required along the ground oblique direction due to the influence of the SAR satellite orbit azimuth angle, respectively calculating the number n of ground oblique direction pixels between the ground pixel points B and A, the number j of east-west pixels and the number m of north-south offset pixels: Wherein, the Representing the angle of incidence of the radar signal, The SAR satellite orbit azimuth angle is represented, R represents the spatial resolution of the precipitation product, and the unit is kilometers; S34, calculating zenith path delay difference in ground oblique distance direction : Wherein gsd denotes the ground pitch direction; s35, calculating the number of pixels occupied by each vertical water vapor layer in the ground inclined distance direction according to the vertical distribution condition of the water vapor in the troposphere: ; s36, further giving the latest weight value of each pixel on the ground on the zenith path delay difference in the ground oblique distance direction : Wherein h represents the average thickness of the troposphere; s37, obtaining a further optimized slope distance to atmosphere delay phase correction model by combining the zenith path delay difference in the ground slope distance direction and the weight value of each pixel on the zenith path delay difference in the ground slope distance direction: Wherein, the For the requested atmospheric delay phase, Representing the wavelength of the radar signal, And The ground distance to zenith path delay difference and the weight value of the ground distance to zenith path delay difference on the pixel i are respectively represented and calculated by the step S34 and the step S36; s38, further calculating the real deformation phase of the earth surface of the research area after the atmospheric delay phase is removed : Wherein, the To remove the differential interference phase of the land leveling effect and the topography phase in the interference pattern, the differential interference phase is calculated by differential interference software, Representing the final true deformation phase of the ground surface; S4, removing an atmospheric delay phase error from the acquired differential interference phase to accurately calculate the deformation of the ground surface along the radar sight direction 。
2. 2. The method for correcting the phase delay of the InSAR atmospheric pressure according to claim 1, wherein the specific steps of step S1 are as follows: s11, performing multi-view processing on SAR images of the synthetic aperture radars with two views and the same orbit to generate an SAR image multi-view intensity map, calculating row and column numbers of a research area in a single-view complex image according to a row and column number and a view number ratio of the research area in the SAR image multi-view intensity map, and then cutting the SAR image to obtain SAR data pairs covering the research area; s12, in remote sensing image processing software, performing geometric correction on the near-infrared vapor product, giving an accurate geographic coordinate position under a vapor product WGS84 coordinate system; In the remote sensing image processing software, firstly, cloud pollution pixels in the water vapor product are removed by utilizing the cloud mask product, and for a small quantity of cloud pollution pixels which are not removed completely, a threshold value is set, the cloud pollution pixels are further removed by utilizing band operation, and all the cloud pollution pixels are replaced with null values; S14, filling the cloud pollution pixels, namely converting the grid data of the vapor products into corresponding vector point data files, taking the vapor value attribute of the data files as a Z value field, and performing spatial interpolation by means of ArcGIS software by utilizing a Kriging interpolation algorithm to obtain a subset of the vapor products capable of removing the cloud pollution pixels.
3. 3. The method for correcting the phase delay of the InSAR atmospheric pressure according to claim 2, wherein the specific steps of step S2 are as follows: s21, registering the auxiliary SAR image to the main SAR image, wherein the registration accuracy is at least 0.1 pixel; S22, resampling the auxiliary SAR image, namely, carrying out phase resampling on the SAR auxiliary image according to a precise registration polynomial and a phase resampling method to obtain a resampled auxiliary SAR image; s23, performing interferometry processing on the main SAR image and the resampled auxiliary SAR image to obtain a differential interference phase 。

Description

InSAR (interferometric synthetic aperture radar) atmospheric delay phase correction method for weighted resampling along ground distance Technical Field The invention relates to the fields of space earth observation, earth measurement, engineering measurement, geophysical and geological disaster monitoring, early identification for obtaining earth surface subsidence information and the like, in particular to the technical fields of earthquake isoseism deformation monitoring, fault layer system sliding and locking degree distribution condition investigation, urban ground subsidence monitoring, mining area earth surface subsidence monitoring caused by underground mining, volcanic eruption mobile monitoring, iceberg and glacier mobile monitoring and the like, and in particular relates to an InSAR atmospheric delay phase correction method for weighting resampling along the earth distance. Background In the past decades, synthetic aperture radar interferometry has been successfully applied to the fields of topographic mapping, ground subsidence monitoring, seismic isomorphous monitoring, and the like. However, in the process of obtaining the surface deformation information by using the synthetic aperture radar SAR interferometry, the high-precision application development of the InSAR technology is severely restricted by the atmospheric delay phase error. In order to reduce the influence of the atmospheric effect on the InSAR measurement accuracy, the scholars at home and abroad mainly propose the following four methods for removing the atmospheric phase delay in the interferogram: Method 1 pair-wise analysis (pair-wise logic). Massonnet A pair-wise analysis was first proposed in 1994 to study Landers post-earthquake deformation. By comparing interference results at different time intervals, the analysis-by-analysis method enables the atmospheric signals to be identified qualitatively and separated from the geophysical signals. The analytical method by analytical method is a basic method for analyzing the atmospheric effect of InSAR. The method can only be used as a means for qualitatively judging whether the atmospheric effect exists, and the atmospheric phase delay value cannot be calculated quantitatively; Method 2, interferogram superposition method (Interferogram stacking) and Relay interferogram superposition method (Relay-INTERFREGRAM STACKING). The interferogram superposition method achieves the aim of reducing the atmospheric effect by carrying out superposition average on N independent interferogram generated by different SAR images in the same research area. The interferogram superposition method is one of methods for early researching atmospheric correction, and needs to assume that the deformation rate is constant, so that the interferogram superposition method cannot be applied to a nonlinear deformation rate area, is extremely sensitive to sudden weather (such as large-scale rainfall and thunder) conditions and can generate serious errors; Method 3 permanent scatterer method (PERMANENT SCATTERERS INSAR, PS InSAR). The permanent scatterer method is to estimate the geophysical signal using discrete and time stable phase values of the natural reflectors. According to the different characteristics of the components such as the residual topography phase, the orbit error phase, the decorrelation phase, the atmospheric delay phase and the noise phase in the differential interference phase in the respective time domain and the space domain (the atmospheric delay phase is uncorrelated in the interferograms with the time base line being greater than 1 day, but the interferograms with the time base line being greater than 1 day show higher spatial correlation), analyzing the total phase of each high-coherence point, gradually stripping and removing each error phase in the total phase, so as to improve the accuracy of the unknown quantities such as the surface deformation phase, the atmospheric delay phase and the like, and remove the atmospheric effect of the high-scattering characteristic points in the interferograms. The permanent scatterer method needs a larger SAR image data set (generally more than 30 scenes), is not beneficial to the practical application of SAR technology, and the PS InSAR technology has high requirements on a research area, and the research area must have a sufficient number of reliable PS points; Method 4 external data (vapor product) space radiometer monitoring method. In recent years, with the improvement of the accuracy and spatial resolution of vapor products, a method of removing the atmospheric effect of InSAR by using a global scale vapor product such as a medium resolution imaging spectrometer (Medium Resolution Imaging Spectrometer, MERIS), a medium resolution imaging spectrometer (the Moderate Resolution Imaging Spectroradiometer, MODIS), a medium weather forecast center in europe (European Centre for Medium-RANGE WEATHER Forecasts, ECMWF) and the like has been attracting