基于站间天然电磁场单位脉冲响应的大地电磁时间序列去噪方法
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摘要
针对天然大地电磁场信号在人文活动密集地区易受噪声干扰的问题,本文提出利用两个同步测点天然电磁场时间序列之间的单位脉冲响应,合成本地点受干扰时段的数据,从而去除大地电磁噪声.首先,选择高信噪比时段的数据,采用最小二乘法,估算本地点与参考点之间的单位脉冲响应,再根据卷积定律,结合参考磁场合成本地点的磁场和电场.最后用合成数据替换含噪声时段数据,实现时间域去噪.实测高信噪比数据和含噪数据的处理结果表明,该方法可以高精度合成本地点磁场与电场信号,有效去除本地点电场和磁场噪声,包括相关噪声,提高大地电磁数据质量.
A new method to construct synthetic natural electric and magnetic time series is proposed,in which the time series of local sites are derived using an impulse response and a reference(STIR).This method based on the assumption that the external source of the magnetic field is uniform,and the electric and magnetic fields acquired on the surface satisfy a timeindependent linear relation in the frequency domain.According to the convolution theorem,we can synthesize natural electric and magnetic time series using the impulse responses of interstation transfer function with a reference.Applying this method,two impulse responses need to be estimated:the quasi-MT impulse response tensor and the horizontal magnetic impulse responsetensor.These impulse response tensors are related to the local horizontal electric and magnetic components with the horizontal magnetic components at a reference site,respectively.Some clean segments of time series are selected to estimate impulse responses by using the least-square(LS)method.A test with good quality of MT data shows that the resulted synthetic time-series agree with the natural electric and magnetic time series.For contaminated MT examples,when this method is used to remove noise present at the local site,the scatters of MT sounding curves are remarkably reduced and the data quality are improved.
A new method to construct synthetic natural electric and magnetic time series is proposed,in which the time series of local sites are derived using an impulse response and a reference(STIR).This method based on the assumption that the external source of the magnetic field is uniform,and the electric and magnetic fields acquired on the surface satisfy a timeindependent linear relation in the frequency domain.According to the convolution theorem,we can synthesize natural electric and magnetic time series using the impulse responses of interstation transfer function with a reference.Applying this method,two impulse responses need to be estimated:the quasi-MT impulse response tensor and the horizontal magnetic impulse responsetensor.These impulse response tensors are related to the local horizontal electric and magnetic components with the horizontal magnetic components at a reference site,respectively.Some clean segments of time series are selected to estimate impulse responses by using the least-square(LS)method.A test with good quality of MT data shows that the resulted synthetic time-series agree with the natural electric and magnetic time series.For contaminated MT examples,when this method is used to remove noise present at the local site,the scatters of MT sounding curves are remarkably reduced and the data quality are improved.
引文
Cagniard L.1953.Basic Theory of the magnetotelluric method of geophysical prospecting.Geophysics,18(3):605-635.
Cai J H,Tang J T,Hua X R,et al.2009.An analysis method for magnetotelluric data based on the Hilbert-Huang Transform.Exploration Geophysics,40(2):197-205.
Cai J H.2014.A combinatorial filtering method for magnetotelluric time-series based on Hilbert-Huang transform.Exploration Geophysics,45(2):63-73.
Chen J,Heincke B,Jegen M,et al.2012a.Using empirical mode decomposition to process marine magnetotelluric data.Geophysical Journal International,190(1):293-309.
Chen T S,Ohlsson H,Ljung L.2012b.On the estimation of transfer functions,regularizations and Gaussian processesRevisited.Automatica,48(8):1525-1535.
Di Q Y,Xue G Q,Lei D,et al.2018.Geophysical survey over molybdenum mines using the newly developed M-TEM System.Journal of Applied Geophysics,158:65-70.
Egbert G D,Booker J R.1986.Robust estimation of geomagnetic transfer functions.Geophysical Journal International,87(1):173-194.
Egbert G D,Booker J R,Schultz A.1992.Very long period magnetotellurics at tucson observatory:estimation of impedances.Journal of Geophysical Research:Solid Earth,97(B11):15113-15128.
Egbert G D.1997.Robust multiple-station magnetotelluric data processing.Geophysical Journal International,130(12):475-496.
Escalas M,Queralt P,Ledo J,et al.2013.Polarisation analysis of magnetotelluric time series using a wavelet-based scheme:a method for detection and characterisation of cultural noise sources.Physics of the Earth and Planetary Interiors,2013,218:31-50.
Gamble T D,Goubau W M,Clarke J.1979.Magnetotellurics with a remote magnetic reference.Geophysics,44(1):53-68.
Goubau W M,Maxton P M,Koch R H,et al.1984.Noise correlation lengths in remote reference magnetotellurics.Geophysics,49(4):433-438.
Huang N E,Shen Z,Long S R,et al.1998.The empirical mode decomposition and the Hilbert spectrum for nonlinear and nonstationary time series analysis.Proceedings of the Royal Society of London.Series A:Mathematical,Physical and Engineering Sciences,454(1971):903-995.
Jin S,Wei W B,Wang S,et al.2010.Discussion of the formation and dynamic signification of the high conductive layer in Tibetan crust.Chinese Journal of Geophysics(in Chinese),53(10):2376-2385,doi:10.3969/j.issn.0001-5733.2010.10.011.
Junge A.1996.Characterization of and correction for cultural noise.Surveys in Geophysics,17(4):361-391.
Kappler K N.2012.A data variance technique for automated despiking of magnetotelluric data with a remote reference.Geophysical Prospecting,60(1):179-191.
Larsen J C.1989.Transfer functions:Smooth robust estimates by least-squares and remote reference methods.Geophysical Journal International,99(3):645-663.
Li J,Tang J T,Wang L,et al.2014.Noise suppression for magnetotelluric sounding data based on signal subspace enhancement and endpoint detection.Acta Physica Sinica(in Chinese),63(1):019101.
Li J,Tang J T,Xu Z M,et al.2017a.Magnetotelluric noise suppression base on signal-to-noise identification in ore concentration area.Chinese Journal of Geophysics(in Chinese),60(2):722-737,doi:10.6038/cjg20170224.
Li J,Tang J T,Yan H,et al.2017b.Identification and spearation of magnetotelluric signal and noise based on recurrence analysis and clustering.Chinese Journal of Geophysics(in Chinese),60(5):1918-1936,doi:10.6038/cjg20170525.
Liu J X,Yan J B,He J S,et al.2003.Robust estimation method of sea magnetotelluric impedance based on correlative coefficient.Chinese Journal of Geophysics(in Chinese),46(2):241-245.
Ljung L.1985.On the estimation of transfer functions.Automatica,21(6):677-696.
Neukirch M,Garcia X.2014.Nonstationary magnetotelluric data processing with instantaneous parameter.Journal of Geophysical Research:Solid Earth,119(3):1634-1654.
Schaa R,Gross L,Du Plessis J.2016.PDE-based geophysical modelling using finite elements:examples from 3D resistivity and 2Dmagnetotellurics.Journal of Geophysics and Engineering,13(2):S59-S73.
Shalivahan N,Bhattacharya B B.2002.How remote can the far remote reference site for magnetotelluric measurements be?.Journal of Geophysical Research:Solid Earth,107(6):2105,doi:10.1029/2000JB000119.
Sims W E,Bostick J X,Smith H W.1971.The estimation of magnetotelluric impedance tensor elements from measured data.Geophysics,36(5):938-942.
Tang J T,Hua X R,Cao Z M,et al.2008.Hilbert-Huang transformation and noise suppression of magnetotelluric sounding data.Chinese Journal of Geophysics(in Chinese),51(2):603-610.
Tang J T,Li J,Xiao X,et al.2012a.Mathematical morphology filtering and noise suppression of magnetotelluric sounding data.Chinese Journal of Geophysics(in Chinese),55(5):1784-1793,doi:10.6038/j.issn.0001-5733.2012.05.036.
Tang J T,Xu Z M,Xiao X,et al.2012b.Effect rules of strong noise on magnetotelluric(MT)sounding in the Luzong ore cluster area.Chinese Journal of Geophysics(in Chinese),55(12):4147-4159,doi:10.6038/j.issn.0001-5733.2012.12.027.
Tang J T,Ren Z Y,Zhou C,et al.2015.Frequency-domain electromagnetic methods for exploration of the shallow subsurface.Chinese Journal of Geophysics(in Chinese),58(8):2681-2705,doi:10.6038/cjg20150807.
Tang J T,Li G,Xiao X,et al.2017.Strong noise separation for magnetotelluric data based on a signal reconstruction algorithm of compressive sensing.Chinese Journal of Geophysics(in Chinese),60(9):3642-3654,doi:10.6038/cjg20170928.
Tary J B,Herrera R H,Han J J,et al.2014.Spectral estimationwhat is new?What is next?.Reviews of Geophysics,52(4):723-749.
Trad D O,Travassos J M.2000.Wavelet filtering of magnetotelluric data.Geophysics,65(2):482-491.
Wang H,Wei W B,Jin S,et al.2014.Removal of magnetotelluric noise based on synchronous time series relationship.Chinese Journal of Geophysics(in Chinese),57(2):531-545,doi:10.6038/cjg20140218.
Wang H,Cheng J L,Teng X Z,et al.2016.Source effect on magnetotelluric data due to mining area and its suppression.Progress in Geophysics(in Chinese),31(3):1358-1366,doi:10.6038/pg20160359.
Wang H,CampanyàJ,Cheng J L,et al.2017.Synthesis of natural electric and magnetic time-series using inter-station transfer functions and time-series from a neighboring site(STIN):applications for processing MT data.Journal of Geophysical Research:Solid Earth,122(8):5835-5851.
Wang S M,Wang J Y.2004.Analysis on statistic characteristics of magnetotelluric signal.Acta Seismologica Sinica(in Chinese),26(6):669-674.
Wei W B,Unsworth M,Jones A,et al.2001.Detection of widespread fluids in the Tibetan crust by magnetotelluric studies.Science,292(5517):716-719.
Xu Y X,Wang J Y.2000.Power spectrum estimation for magnetotelluric signal based on continuous wavelet transform.Chinese Journal of Geophysics(in Chinese),43(5):677-683.
Zhao G Z,Chen X B,Tang J.2007.Advanced geo-electromagnetic methods in China.Progress in Geophysics(in Chinese),22(4):1171-1180.
Zhao G Z,Chen X B,Wang L F,et al.2008.Evidence of the electromagnetic probe on the eastern edge crust“pipe flow”layer.Science Bulletin(in Chinese),53(3):345-350.
金胜,魏文博,汪硕等.2010.青藏高原地壳高导层的成因及动力学意义探讨-大地电磁探测提供的证据.地球物理学报,53(10):2376-2385,doi:10.3969/j.issn.0001-5733.2010.10.011.
李晋,汤井田,王玲等.2014.基于信号子空间增强和端点检测的大地电磁噪声压制.物理学报,63(1):019101.
李晋,汤井田,徐志敏等.2017a.基于信噪辨识的矿集区大地电磁噪声压制.地球物理学报,60(2):722-737,doi:10.6038/cjg20170224.
李晋,汤井田,燕欢等.2017b.基于递归分析和聚类的大地电磁信噪辨识及分离.地球物理学报,60(5):1918-1936,doi:10.6038/cjg20170525.
柳建新,严家斌,何继善等.2003.基于相关系数的海底大地电磁阻抗Robust估算方法.地球物理学报,46(2):241-245.
汤井田,化希瑞,曹哲民等.2008.Hibert-Huang变换与大地电磁噪声压制.地球物理学报,51(3):603-610.
汤井田,李晋,肖晓等.2012a.数学形态滤波与大地电磁噪声压制.地球物理学报,55(5):1784-1793,doi:10.6038/j.issn.0001-5733.2012.05.036.
汤井田,徐志敏,肖晓等.2012b.庐枞矿集区大地电磁测深强噪声的影响规律.地球物理学报,55(12):4147-4159,doi:10.6038/j.issn.0001-5733.2012.12.027.
汤井田,任政勇,周聪等.2015.浅部频率域电磁勘探方法综述.地球物理学报,58(8):2681-2705,doi:10.6038/cjg20150807.
汤井田,李广,肖晓等.2017.基于压缩感知重构算法的大地电磁强干扰分离.地球物理学报,60(9):3642-3654,doi:10.6038/cjg20170928.
王辉,魏文博,金胜等.2014.基于同步大地电磁时间序列依赖关系的噪声处理.地球物理学报,57(2):531-545,doi:10.6038/cjg20140218.
王辉,程久龙,腾星智等.2016.矿区近场源噪声对大地电磁测深数据的影响及其压制方法.地球物理学进展,31(3):1358-1366,doi:10.6038/pg20160359.
王书明,王家映.2004.大地电磁信号统计特征分析.地震学报,26(6):669-674.
徐义贤,王家映.2000.基于连续小波变换的大地电磁信号谱估计方法.地球物理学报,43(5):677-683.
赵国泽,陈小斌,汤吉.2007.中国地球电磁法新进展和发展趋势.地球物理学进展,22(4):1171-1180.
赵国泽,陈小斌,王立凤等.2008.青藏高原东边缘地壳“管流”层的电磁探测证据.科学通报,53(3):345-350.
Cai J H,Tang J T,Hua X R,et al.2009.An analysis method for magnetotelluric data based on the Hilbert-Huang Transform.Exploration Geophysics,40(2):197-205.
Cai J H.2014.A combinatorial filtering method for magnetotelluric time-series based on Hilbert-Huang transform.Exploration Geophysics,45(2):63-73.
Chen J,Heincke B,Jegen M,et al.2012a.Using empirical mode decomposition to process marine magnetotelluric data.Geophysical Journal International,190(1):293-309.
Chen T S,Ohlsson H,Ljung L.2012b.On the estimation of transfer functions,regularizations and Gaussian processesRevisited.Automatica,48(8):1525-1535.
Di Q Y,Xue G Q,Lei D,et al.2018.Geophysical survey over molybdenum mines using the newly developed M-TEM System.Journal of Applied Geophysics,158:65-70.
Egbert G D,Booker J R.1986.Robust estimation of geomagnetic transfer functions.Geophysical Journal International,87(1):173-194.
Egbert G D,Booker J R,Schultz A.1992.Very long period magnetotellurics at tucson observatory:estimation of impedances.Journal of Geophysical Research:Solid Earth,97(B11):15113-15128.
Egbert G D.1997.Robust multiple-station magnetotelluric data processing.Geophysical Journal International,130(12):475-496.
Escalas M,Queralt P,Ledo J,et al.2013.Polarisation analysis of magnetotelluric time series using a wavelet-based scheme:a method for detection and characterisation of cultural noise sources.Physics of the Earth and Planetary Interiors,2013,218:31-50.
Gamble T D,Goubau W M,Clarke J.1979.Magnetotellurics with a remote magnetic reference.Geophysics,44(1):53-68.
Goubau W M,Maxton P M,Koch R H,et al.1984.Noise correlation lengths in remote reference magnetotellurics.Geophysics,49(4):433-438.
Huang N E,Shen Z,Long S R,et al.1998.The empirical mode decomposition and the Hilbert spectrum for nonlinear and nonstationary time series analysis.Proceedings of the Royal Society of London.Series A:Mathematical,Physical and Engineering Sciences,454(1971):903-995.
Jin S,Wei W B,Wang S,et al.2010.Discussion of the formation and dynamic signification of the high conductive layer in Tibetan crust.Chinese Journal of Geophysics(in Chinese),53(10):2376-2385,doi:10.3969/j.issn.0001-5733.2010.10.011.
Junge A.1996.Characterization of and correction for cultural noise.Surveys in Geophysics,17(4):361-391.
Kappler K N.2012.A data variance technique for automated despiking of magnetotelluric data with a remote reference.Geophysical Prospecting,60(1):179-191.
Larsen J C.1989.Transfer functions:Smooth robust estimates by least-squares and remote reference methods.Geophysical Journal International,99(3):645-663.
Li J,Tang J T,Wang L,et al.2014.Noise suppression for magnetotelluric sounding data based on signal subspace enhancement and endpoint detection.Acta Physica Sinica(in Chinese),63(1):019101.
Li J,Tang J T,Xu Z M,et al.2017a.Magnetotelluric noise suppression base on signal-to-noise identification in ore concentration area.Chinese Journal of Geophysics(in Chinese),60(2):722-737,doi:10.6038/cjg20170224.
Li J,Tang J T,Yan H,et al.2017b.Identification and spearation of magnetotelluric signal and noise based on recurrence analysis and clustering.Chinese Journal of Geophysics(in Chinese),60(5):1918-1936,doi:10.6038/cjg20170525.
Liu J X,Yan J B,He J S,et al.2003.Robust estimation method of sea magnetotelluric impedance based on correlative coefficient.Chinese Journal of Geophysics(in Chinese),46(2):241-245.
Ljung L.1985.On the estimation of transfer functions.Automatica,21(6):677-696.
Neukirch M,Garcia X.2014.Nonstationary magnetotelluric data processing with instantaneous parameter.Journal of Geophysical Research:Solid Earth,119(3):1634-1654.
Schaa R,Gross L,Du Plessis J.2016.PDE-based geophysical modelling using finite elements:examples from 3D resistivity and 2Dmagnetotellurics.Journal of Geophysics and Engineering,13(2):S59-S73.
Shalivahan N,Bhattacharya B B.2002.How remote can the far remote reference site for magnetotelluric measurements be?.Journal of Geophysical Research:Solid Earth,107(6):2105,doi:10.1029/2000JB000119.
Sims W E,Bostick J X,Smith H W.1971.The estimation of magnetotelluric impedance tensor elements from measured data.Geophysics,36(5):938-942.
Tang J T,Hua X R,Cao Z M,et al.2008.Hilbert-Huang transformation and noise suppression of magnetotelluric sounding data.Chinese Journal of Geophysics(in Chinese),51(2):603-610.
Tang J T,Li J,Xiao X,et al.2012a.Mathematical morphology filtering and noise suppression of magnetotelluric sounding data.Chinese Journal of Geophysics(in Chinese),55(5):1784-1793,doi:10.6038/j.issn.0001-5733.2012.05.036.
Tang J T,Xu Z M,Xiao X,et al.2012b.Effect rules of strong noise on magnetotelluric(MT)sounding in the Luzong ore cluster area.Chinese Journal of Geophysics(in Chinese),55(12):4147-4159,doi:10.6038/j.issn.0001-5733.2012.12.027.
Tang J T,Ren Z Y,Zhou C,et al.2015.Frequency-domain electromagnetic methods for exploration of the shallow subsurface.Chinese Journal of Geophysics(in Chinese),58(8):2681-2705,doi:10.6038/cjg20150807.
Tang J T,Li G,Xiao X,et al.2017.Strong noise separation for magnetotelluric data based on a signal reconstruction algorithm of compressive sensing.Chinese Journal of Geophysics(in Chinese),60(9):3642-3654,doi:10.6038/cjg20170928.
Tary J B,Herrera R H,Han J J,et al.2014.Spectral estimationwhat is new?What is next?.Reviews of Geophysics,52(4):723-749.
Trad D O,Travassos J M.2000.Wavelet filtering of magnetotelluric data.Geophysics,65(2):482-491.
Wang H,Wei W B,Jin S,et al.2014.Removal of magnetotelluric noise based on synchronous time series relationship.Chinese Journal of Geophysics(in Chinese),57(2):531-545,doi:10.6038/cjg20140218.
Wang H,Cheng J L,Teng X Z,et al.2016.Source effect on magnetotelluric data due to mining area and its suppression.Progress in Geophysics(in Chinese),31(3):1358-1366,doi:10.6038/pg20160359.
Wang H,CampanyàJ,Cheng J L,et al.2017.Synthesis of natural electric and magnetic time-series using inter-station transfer functions and time-series from a neighboring site(STIN):applications for processing MT data.Journal of Geophysical Research:Solid Earth,122(8):5835-5851.
Wang S M,Wang J Y.2004.Analysis on statistic characteristics of magnetotelluric signal.Acta Seismologica Sinica(in Chinese),26(6):669-674.
Wei W B,Unsworth M,Jones A,et al.2001.Detection of widespread fluids in the Tibetan crust by magnetotelluric studies.Science,292(5517):716-719.
Xu Y X,Wang J Y.2000.Power spectrum estimation for magnetotelluric signal based on continuous wavelet transform.Chinese Journal of Geophysics(in Chinese),43(5):677-683.
Zhao G Z,Chen X B,Tang J.2007.Advanced geo-electromagnetic methods in China.Progress in Geophysics(in Chinese),22(4):1171-1180.
Zhao G Z,Chen X B,Wang L F,et al.2008.Evidence of the electromagnetic probe on the eastern edge crust“pipe flow”layer.Science Bulletin(in Chinese),53(3):345-350.
金胜,魏文博,汪硕等.2010.青藏高原地壳高导层的成因及动力学意义探讨-大地电磁探测提供的证据.地球物理学报,53(10):2376-2385,doi:10.3969/j.issn.0001-5733.2010.10.011.
李晋,汤井田,王玲等.2014.基于信号子空间增强和端点检测的大地电磁噪声压制.物理学报,63(1):019101.
李晋,汤井田,徐志敏等.2017a.基于信噪辨识的矿集区大地电磁噪声压制.地球物理学报,60(2):722-737,doi:10.6038/cjg20170224.
李晋,汤井田,燕欢等.2017b.基于递归分析和聚类的大地电磁信噪辨识及分离.地球物理学报,60(5):1918-1936,doi:10.6038/cjg20170525.
柳建新,严家斌,何继善等.2003.基于相关系数的海底大地电磁阻抗Robust估算方法.地球物理学报,46(2):241-245.
汤井田,化希瑞,曹哲民等.2008.Hibert-Huang变换与大地电磁噪声压制.地球物理学报,51(3):603-610.
汤井田,李晋,肖晓等.2012a.数学形态滤波与大地电磁噪声压制.地球物理学报,55(5):1784-1793,doi:10.6038/j.issn.0001-5733.2012.05.036.
汤井田,徐志敏,肖晓等.2012b.庐枞矿集区大地电磁测深强噪声的影响规律.地球物理学报,55(12):4147-4159,doi:10.6038/j.issn.0001-5733.2012.12.027.
汤井田,任政勇,周聪等.2015.浅部频率域电磁勘探方法综述.地球物理学报,58(8):2681-2705,doi:10.6038/cjg20150807.
汤井田,李广,肖晓等.2017.基于压缩感知重构算法的大地电磁强干扰分离.地球物理学报,60(9):3642-3654,doi:10.6038/cjg20170928.
王辉,魏文博,金胜等.2014.基于同步大地电磁时间序列依赖关系的噪声处理.地球物理学报,57(2):531-545,doi:10.6038/cjg20140218.
王辉,程久龙,腾星智等.2016.矿区近场源噪声对大地电磁测深数据的影响及其压制方法.地球物理学进展,31(3):1358-1366,doi:10.6038/pg20160359.
王书明,王家映.2004.大地电磁信号统计特征分析.地震学报,26(6):669-674.
徐义贤,王家映.2000.基于连续小波变换的大地电磁信号谱估计方法.地球物理学报,43(5):677-683.
赵国泽,陈小斌,汤吉.2007.中国地球电磁法新进展和发展趋势.地球物理学进展,22(4):1171-1180.
赵国泽,陈小斌,王立凤等.2008.青藏高原东边缘地壳“管流”层的电磁探测证据.科学通报,53(3):345-350.
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