InSAR生成DEM中WRF大气校正
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摘要
利用星载重复轨道合成孔径雷达干涉测量InSAR技术获取数字高程模型(DEM),无法避免大气延迟效应的影响。InSAR大气校正的方法很多,但在DEM获取方面的大气校正研究却非常少见。本文研究星载重轨InSAR生产DEM时利用大气数值模式WRF(Weather Research and Forecasting model)得到的水汽结果进行大气校正的问题,重点讨论大气校正的策略,包括WRF模式设置和大气校正时机的选择,简要介绍了基于WRF运算结果的大气校正方法。利用Terra SAR-X数据进行实验,检验了所提出方法的有效性,证明了在干涉相位解缠前进行大气校正,比在相位解缠后进行的效果更好。将所提出方法应用于多基线、多波段InSAR干涉结果融合中,实验结果表明大气校正能够有效降低误差,对于相干性较高的地区效果更好。
Atmospheric delay effect is unavoidable and sometimes serious when using spaceborne repeat-pass synthetic aperture radar interferometry(InSAR) to generate Digital Elevation Models(DEMs). InSAR atmospheric correction methods come in various types. However,they are rarely used in InSAR DEM generation. The method based on atmospheric numerical models offersunique advantages.It can estimate atmospheric water vapor field at the SAR data acquisition time, and it is not affected by clouds. Therefore, this work studies the atmospheric correction strategy and method during the process of InSAR DEM generation based on the atmospheric numerical model called the Weather Research and Forecasting(WFR) model to improve the accuracy of the generated InSAR DEM.First, atmospheric correction strategies are discussed. These strategies include the proper settings of WRF Preprocessing System(WPS)to make the temporal and spatial scales of WRF results match those of SAR data, as well as the selection of a proper atmospheric correction timing to improve the accuracy of InSAR DEMs. One of the key issues of InSAR is phase unwrapping, and atmospheric correction removes the residual atmospheric phase from the interferometric phase of SAR data. Thus, there are two possible atmospheric correction timings: before phase unwrapping and after phase unwrapping. Atmospheric correction before phase unwrapping is theoretically helpful for phase unwrapping because the contribution of the atmosphere is removed. Atmospheric correction after phase unwrapping is commonly used in the field of Differential InSAR(D-InSAR), and its efficiency has been validated. The topographic phase in the process of D-InSAR is removed before phase unwrapping, which makes phase unwrapping easier than that in the process of InSAR DEM generation. A method of atmospheric correction based on WRF results is then introduced. The direct output results of WRF are not atmospheric water vapor field, which is needed to calculate the residual atmospheric phase. Thus, a method for transforming the direct output results of WRF to integrated water vapor(IWV) andthen transforming the IWV to the residual atmospheric phase is introduced. The original coordinates of the WRF results are transformed to the coordinates of SAR data. A workflow of atmospheric correction during the process of InSAR DEM generation is proposed. Experiments are carried outwith Terra SAR-X data to validate the efficiency of the proposed methods. The accuracies of the generated InSAR DEMs with residual atmospheric phase corrected at each possible timing are compared. The compared qualitative and quantitative results prove that the atmospheric corrections work at both timings and that the atmospheric correction before phase unwrapping performs well. However, the atmospheric correction before phase unwrapping may not always work or may worsen the accuracy of the DEM resultin regions where interferometric qualities are poor. The proposed methods are then applied to the fusion of multi-baseline and multi-frequency InSAR results, with the experimental resultsalso proving the efficiency of the methods and the good performance of atmospheric correctionin regions of good interferometric quality.
Atmospheric delay effect is unavoidable and sometimes serious when using spaceborne repeat-pass synthetic aperture radar interferometry(InSAR) to generate Digital Elevation Models(DEMs). InSAR atmospheric correction methods come in various types. However,they are rarely used in InSAR DEM generation. The method based on atmospheric numerical models offersunique advantages.It can estimate atmospheric water vapor field at the SAR data acquisition time, and it is not affected by clouds. Therefore, this work studies the atmospheric correction strategy and method during the process of InSAR DEM generation based on the atmospheric numerical model called the Weather Research and Forecasting(WFR) model to improve the accuracy of the generated InSAR DEM.First, atmospheric correction strategies are discussed. These strategies include the proper settings of WRF Preprocessing System(WPS)to make the temporal and spatial scales of WRF results match those of SAR data, as well as the selection of a proper atmospheric correction timing to improve the accuracy of InSAR DEMs. One of the key issues of InSAR is phase unwrapping, and atmospheric correction removes the residual atmospheric phase from the interferometric phase of SAR data. Thus, there are two possible atmospheric correction timings: before phase unwrapping and after phase unwrapping. Atmospheric correction before phase unwrapping is theoretically helpful for phase unwrapping because the contribution of the atmosphere is removed. Atmospheric correction after phase unwrapping is commonly used in the field of Differential InSAR(D-InSAR), and its efficiency has been validated. The topographic phase in the process of D-InSAR is removed before phase unwrapping, which makes phase unwrapping easier than that in the process of InSAR DEM generation. A method of atmospheric correction based on WRF results is then introduced. The direct output results of WRF are not atmospheric water vapor field, which is needed to calculate the residual atmospheric phase. Thus, a method for transforming the direct output results of WRF to integrated water vapor(IWV) andthen transforming the IWV to the residual atmospheric phase is introduced. The original coordinates of the WRF results are transformed to the coordinates of SAR data. A workflow of atmospheric correction during the process of InSAR DEM generation is proposed. Experiments are carried outwith Terra SAR-X data to validate the efficiency of the proposed methods. The accuracies of the generated InSAR DEMs with residual atmospheric phase corrected at each possible timing are compared. The compared qualitative and quantitative results prove that the atmospheric corrections work at both timings and that the atmospheric correction before phase unwrapping performs well. However, the atmospheric correction before phase unwrapping may not always work or may worsen the accuracy of the DEM resultin regions where interferometric qualities are poor. The proposed methods are then applied to the fusion of multi-baseline and multi-frequency InSAR results, with the experimental resultsalso proving the efficiency of the methods and the good performance of atmospheric correctionin regions of good interferometric quality.
引文
Bevis M,Chiswell S,Businger S,Herring T A and Bock Y.1996.Es timating wet delays using numerical weather analyses and predic tions.Radio Science,31(3):477-487[DOI:10.1029/96RS00008]
Chen F L,Lin H and Cheng S L.2013.Principles,Methods and Ap plications of Space-borne SAR Interferometry and Time-series Analysis.Beijing:Science Press(陈富龙,林珲,程世来.2013.星载雷达干涉测量及时间序列分析的原理、方法与应用.北京:科学出版社)
Chen Y H,Guo J M,Chen P X and Huang C J.2015.Reduction of at mospheric effects on In SAR interferograms based on CORSJournal of Geodesy and Geodynamics,35(6):1026-1030(陈元洪郭际明,陈品祥,黄长军.2015.基于CORS的DIn SAR大气延迟校正方法研究.大地测量与地球动力学,35(6):1026-1030[DOI:10.14075/j.jgg.2015.06.025]
Cui X A.2013.The Removal of the Atmospheric Water Vapor Effects in Repeat-Pass In SAR Measurements.Beijing:Peking University(崔喜爱.2013.重轨星载In SAR大气水汽效应去除研究.北京北京大学)
Cui X A,Zeng Q M,Tong Q X,Jiao J and Liang C R.2013.In SAR at mospheric effects analysis of ASAR image mode products.Acta Scientiarum Naturalium Universitatis Pekinensis,49(4):643-649(崔喜爱,曾琪明,童庆禧,焦健,梁存任.2013.条带式InSAR大气效应影响分析研究.北京大学学报(自然科学版)49(4):643-649)
Cui X A,Zeng Q M,Tong Q X,Jiao J and Liang C R.2014.Overview of the atmospheric correction methods in repeat-pass In SAR meas urements.Remote Sensing Technology and Application,29(1)9-17(崔喜爱,曾琪明,童庆禧,焦健,梁存任.2014.InSAR测量中的大气校正方法综述.遥感技术与应用,29(1)9-17)[DOI:10.11873/j.issn.1004-0323.2014.1.0009]
Eineder M and Adam N.2005.A maximum-likelihood estimator to sim ultaneously unwrap,geocode,and fuse SAR interferograms from different viewing geometries into one digital elevation model.IEEE Transactions on Geoscience and Remote Sensing43(1):24-36[DOI:10.1109/TGRS.2004.838389]
Hanssen R F.1998.Atmospheric Heterogeneities in ERSTandem SARInterferometry.Delft,The Netherlands:Delft University Press
Hua F F,Zhang J X,Huang G M and Wang M M.2014.Improved maximum likelihood height estimation method for multi-baseline In SAR elevation inversion.Science of Surveying and Mapping39(3):13-18(花奋奋,张继贤,黄国满,王萌萌.2014.面向多基线干涉SAR高程反演的改进最大似然高程估计方法.测绘科学39(3):13-18)
Jiang T C,Li T and Liu J N.2011.Study on Scan SAR interferometry for monitoring large scale earthquake.Geomatics and Information Science of Wuhan University,36(4):490-494(蒋廷臣,李陶,刘经南.2011.星载宽幅雷达干涉监测大范围地震形变技术研究武汉大学学报(信息科学版),36(4):490-494)
Li Z H,Muller J P and Cross P.2003.Comparison of precipitable wa ter vapor derived from radiosonde,GPS,and moderate-resolution imaging spectroradiometer measurements.Journal of Geophysica Research,108(D20)[DOI:10.1029/2003JD003372]
Li Z W,Ding X L and Liu G X.2004.Modeling atmospheric effects on In SAR with meteorological and continuous GPS observations:al gorithms and some test results.Journal of Atmospheric and Solar Terrestrial Physics,66(11):907-917[DOI:10.1016/j.jastp.200402.006]
NCAR.2015.ARW users guide v3[EB/OL].[2015-10-12]http://www2.mmm.ucar.edu/wrf/users/docs/user_guide_V3/con tents.html
Pang L,Zhang J X and Fan H D.2010.Progress and tendency of multi baseline synthetic aperture radar interferometry technique.Acta Electronica Sinica,38(9):2152-2157(庞蕾,张继贤,范洪冬2010.多基线干涉SAR测量技术发展与趋势分析.电子学报38(9):2152-2157)
Perissin D,Pichelli E,Ferretti R,Rocca F and Pierdicca N.2009.The MM5Numerical Model to Correct PSIn SAR Atmospheric Phase Screen.Frascati,Italy
Sandwell D T and Price E J.1998.Phase gradient approach to stacking interferograms.Journal of Geophysical Research-Solid Earth103(B12):30183-30204[DOI:10.1029/1998JB900008]
Sandwell D T and Sichoix L.2000.Topographic phase recovery from stackeders interferometry and a low-resolution digital elevation model.Journal of Geophysical Research-Solid Earth,105(B12)28211-28222[DOI:10.1029/2000JB900340]
Wegmuller U.1999.Automated terrain corrected SAR geocoding//Pro ceedings of 1999 IEEE International Geoscience and Remote Sensing Symposium(IGARSS).Hamburg,Germany:IEEE1712-1714[DOI:10.1109/IGARSS.1999.772070]
Xiong S T.2014.Improvement of PS-In SARBased on Atmospheric Correction by Using WRF Model.Beijing:Peking University(熊思婷.2014.基于WRF大气校正的PS-In SAR方法改进.北京:北京大学)
Xu C J,Wang H,Ge LL,Yonezawa C and Cheng P.2006.In SAR tro pospheric delay mitigation by GPS observations:a case study in Tokyo area.Journal of Atmospheric and Solar-Terrestrial Physics68(6):629-638[DOI:10.1016/j.jastp.2005.11.010]
Yun Y.2015.Mitigating Atmospheric Effects in Repeat-Pass Space borne In SAR Measurement Through Data Assimilation and Nu merical Simulations with WRF Model.Beijing:Peking University(云烨.2015.基于WRF和数据同化的星载重轨In SAR大气校正研究.北京:北京大学)
Yun Y,Zeng Q M,Green B W and Zhang F Q.2015.Mitigating atmo spheric effects in In SAR measurements through high-resolution data assimilation and numerical simulations with a weather predic tion model.International Journal of Remote Sensing,36(8)2129-2147[DOI:10.1080/01431161.2015.1034894]
Zebker H A and Villasenor J.1992.Decorrelation in interferometric radar echoes.IEEE Transactions on Geoscience and Remote Sens ing,30(5):950-959[DOI:10.1109/36.175330]
Zebker H A,Rosen P A and Hensley S.1997.Atmospheric effects in interferometric synthetic aperture radar surface deformation and topographic maps.Journal of Geophysical Research-Solid Earth102(B4):7547-7563[DOI:10.1029/96JB03804]
Zhang X J,Zeng Q M,Jiao J and Zhang J F.2016.Fusion of space borne multi-baseline and multi-frequency interferometric results based on extended Kalman filter to generate high quality DEMs.ISPRS Journal of Photogrammetry and Remote Sensing111:32-44[DOI:10.1016/j.isprsjprs.2015.11.005]
Chen F L,Lin H and Cheng S L.2013.Principles,Methods and Ap plications of Space-borne SAR Interferometry and Time-series Analysis.Beijing:Science Press(陈富龙,林珲,程世来.2013.星载雷达干涉测量及时间序列分析的原理、方法与应用.北京:科学出版社)
Chen Y H,Guo J M,Chen P X and Huang C J.2015.Reduction of at mospheric effects on In SAR interferograms based on CORSJournal of Geodesy and Geodynamics,35(6):1026-1030(陈元洪郭际明,陈品祥,黄长军.2015.基于CORS的DIn SAR大气延迟校正方法研究.大地测量与地球动力学,35(6):1026-1030[DOI:10.14075/j.jgg.2015.06.025]
Cui X A.2013.The Removal of the Atmospheric Water Vapor Effects in Repeat-Pass In SAR Measurements.Beijing:Peking University(崔喜爱.2013.重轨星载In SAR大气水汽效应去除研究.北京北京大学)
Cui X A,Zeng Q M,Tong Q X,Jiao J and Liang C R.2013.In SAR at mospheric effects analysis of ASAR image mode products.Acta Scientiarum Naturalium Universitatis Pekinensis,49(4):643-649(崔喜爱,曾琪明,童庆禧,焦健,梁存任.2013.条带式InSAR大气效应影响分析研究.北京大学学报(自然科学版)49(4):643-649)
Cui X A,Zeng Q M,Tong Q X,Jiao J and Liang C R.2014.Overview of the atmospheric correction methods in repeat-pass In SAR meas urements.Remote Sensing Technology and Application,29(1)9-17(崔喜爱,曾琪明,童庆禧,焦健,梁存任.2014.InSAR测量中的大气校正方法综述.遥感技术与应用,29(1)9-17)[DOI:10.11873/j.issn.1004-0323.2014.1.0009]
Eineder M and Adam N.2005.A maximum-likelihood estimator to sim ultaneously unwrap,geocode,and fuse SAR interferograms from different viewing geometries into one digital elevation model.IEEE Transactions on Geoscience and Remote Sensing43(1):24-36[DOI:10.1109/TGRS.2004.838389]
Hanssen R F.1998.Atmospheric Heterogeneities in ERSTandem SARInterferometry.Delft,The Netherlands:Delft University Press
Hua F F,Zhang J X,Huang G M and Wang M M.2014.Improved maximum likelihood height estimation method for multi-baseline In SAR elevation inversion.Science of Surveying and Mapping39(3):13-18(花奋奋,张继贤,黄国满,王萌萌.2014.面向多基线干涉SAR高程反演的改进最大似然高程估计方法.测绘科学39(3):13-18)
Jiang T C,Li T and Liu J N.2011.Study on Scan SAR interferometry for monitoring large scale earthquake.Geomatics and Information Science of Wuhan University,36(4):490-494(蒋廷臣,李陶,刘经南.2011.星载宽幅雷达干涉监测大范围地震形变技术研究武汉大学学报(信息科学版),36(4):490-494)
Li Z H,Muller J P and Cross P.2003.Comparison of precipitable wa ter vapor derived from radiosonde,GPS,and moderate-resolution imaging spectroradiometer measurements.Journal of Geophysica Research,108(D20)[DOI:10.1029/2003JD003372]
Li Z W,Ding X L and Liu G X.2004.Modeling atmospheric effects on In SAR with meteorological and continuous GPS observations:al gorithms and some test results.Journal of Atmospheric and Solar Terrestrial Physics,66(11):907-917[DOI:10.1016/j.jastp.200402.006]
NCAR.2015.ARW users guide v3[EB/OL].[2015-10-12]http://www2.mmm.ucar.edu/wrf/users/docs/user_guide_V3/con tents.html
Pang L,Zhang J X and Fan H D.2010.Progress and tendency of multi baseline synthetic aperture radar interferometry technique.Acta Electronica Sinica,38(9):2152-2157(庞蕾,张继贤,范洪冬2010.多基线干涉SAR测量技术发展与趋势分析.电子学报38(9):2152-2157)
Perissin D,Pichelli E,Ferretti R,Rocca F and Pierdicca N.2009.The MM5Numerical Model to Correct PSIn SAR Atmospheric Phase Screen.Frascati,Italy
Sandwell D T and Price E J.1998.Phase gradient approach to stacking interferograms.Journal of Geophysical Research-Solid Earth103(B12):30183-30204[DOI:10.1029/1998JB900008]
Sandwell D T and Sichoix L.2000.Topographic phase recovery from stackeders interferometry and a low-resolution digital elevation model.Journal of Geophysical Research-Solid Earth,105(B12)28211-28222[DOI:10.1029/2000JB900340]
Wegmuller U.1999.Automated terrain corrected SAR geocoding//Pro ceedings of 1999 IEEE International Geoscience and Remote Sensing Symposium(IGARSS).Hamburg,Germany:IEEE1712-1714[DOI:10.1109/IGARSS.1999.772070]
Xiong S T.2014.Improvement of PS-In SARBased on Atmospheric Correction by Using WRF Model.Beijing:Peking University(熊思婷.2014.基于WRF大气校正的PS-In SAR方法改进.北京:北京大学)
Xu C J,Wang H,Ge LL,Yonezawa C and Cheng P.2006.In SAR tro pospheric delay mitigation by GPS observations:a case study in Tokyo area.Journal of Atmospheric and Solar-Terrestrial Physics68(6):629-638[DOI:10.1016/j.jastp.2005.11.010]
Yun Y.2015.Mitigating Atmospheric Effects in Repeat-Pass Space borne In SAR Measurement Through Data Assimilation and Nu merical Simulations with WRF Model.Beijing:Peking University(云烨.2015.基于WRF和数据同化的星载重轨In SAR大气校正研究.北京:北京大学)
Yun Y,Zeng Q M,Green B W and Zhang F Q.2015.Mitigating atmo spheric effects in In SAR measurements through high-resolution data assimilation and numerical simulations with a weather predic tion model.International Journal of Remote Sensing,36(8)2129-2147[DOI:10.1080/01431161.2015.1034894]
Zebker H A and Villasenor J.1992.Decorrelation in interferometric radar echoes.IEEE Transactions on Geoscience and Remote Sens ing,30(5):950-959[DOI:10.1109/36.175330]
Zebker H A,Rosen P A and Hensley S.1997.Atmospheric effects in interferometric synthetic aperture radar surface deformation and topographic maps.Journal of Geophysical Research-Solid Earth102(B4):7547-7563[DOI:10.1029/96JB03804]
Zhang X J,Zeng Q M,Jiao J and Zhang J F.2016.Fusion of space borne multi-baseline and multi-frequency interferometric results based on extended Kalman filter to generate high quality DEMs.ISPRS Journal of Photogrammetry and Remote Sensing111:32-44[DOI:10.1016/j.isprsjprs.2015.11.005]