基于COSMIC掩星数据探测汶川M_S8.0地震震前电离层异常
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摘要
获取COSMIC掩星2级数据,基于球谐函数使用最小二乘拟合法计算模型值,为2008年5月12日汶川MS8.0地震前电离层电子密度变化提供背景依据.同时应用主成分分析法研究最大电子密度,得到各主成分所占能量百分比随时间的变化.研究结果发现,震前在震中邻近区域出现电离层扰动增强现象,且随高度不同存在一定差异,主要集中在F2层300—450km.主成分分析结果显示,4月15日—29日19:00—24:00(地方时)第三主成分能量百分比显著增加.上述结果表明,震前电离层存在异常扰动现象.这一研究结果有助于加强地震电离层耦合机理方面的研究.
By a least-squares fitting method we calculated the coefficients of spherical harmonic functions,and examined electron density in and around epicentral region of the Wenchuan MS8.0earthquake based on COSMIC occultation data.At the same time we evaluated the maximum electron density using the principal component analysis,and deduced the temporal variation of the contribution of each principal component.It was found that the enhanced anomalous TEC disturbances over seismogenic zone took place before the Wenchuan earthquake in the layer from altitude of 300km to 450km,further more the disturbance changed with height.The third principal component increased significantly during 19:00—24:00(local time)within 13—27days(from April 15to 29)prior to the Wenchuan earthquake.The results showed that there was a clear ionospheric anomaly before the Wenchuan earthquake.Result of this study helps us in understanding the seismic-ionospheric coupling model.
By a least-squares fitting method we calculated the coefficients of spherical harmonic functions,and examined electron density in and around epicentral region of the Wenchuan MS8.0earthquake based on COSMIC occultation data.At the same time we evaluated the maximum electron density using the principal component analysis,and deduced the temporal variation of the contribution of each principal component.It was found that the enhanced anomalous TEC disturbances over seismogenic zone took place before the Wenchuan earthquake in the layer from altitude of 300km to 450km,further more the disturbance changed with height.The third principal component increased significantly during 19:00—24:00(local time)within 13—27days(from April 15to 29)prior to the Wenchuan earthquake.The results showed that there was a clear ionospheric anomaly before the Wenchuan earthquake.Result of this study helps us in understanding the seismic-ionospheric coupling model.
引文
刘立波,万卫星,陈一定,乐会军.2011.电离层与太阳活动性关系[J].科学通报,56(7):477--487.
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王武星,丁鉴海,余素荣,张永仙.2009.汶川MS8 .0地震前地磁短临异常与强震预测控索[J].地震学报,31(2):172--179.
袁运斌,欧吉坤.2002.基于GPS的电离层监测及延迟改正理论与方法的研究[J].科学通报,47(8):636--639.
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祝芙英,吴云,林剑,周义炎,熊晶,杨剑.2009.汶川地震前电离层VTEC的异常响应[J].地震学报,31(2):180--187.
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Du A M,Tsurutani B T,Sun W.2008.Anomalous geomagnetic storm of 21—22January 2005:A storm main phase during northward IMFs[J].J Geophys Res,113:A10214,doi:10.1029/2008JA013284.
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Fenoglio M A,Johnston M J S,Byerlee J D.1995.Magnetic and electric fields associated with changes in high pore pressure in fault zones:Application to the Loma Prieta ULF emissions[J].J Geophys Res,100(B7):12951--12958.
Freund F T,Takeuchi A,Lau B W S,Post R,Keefner J,Melwn J,Al-Manaseer A.2004.Stress-induced changes in the electrical conductivity of igneous rocks and the generation of ground currents[J].Terrestrial Atomospheric and Oceanic Sciences,15(3):437--468.
Hayakawa M,Molchanov O A,NASDA/UEC team.2004.Summary report of NASDA’s earthquake remote sensing frontier project[J].Phys Chem Earth,29:617--625.
Huang Q.2002.One possible generation mechanism of co-seismic electric signals[J].Proceedings of the Japan Academy(B:Physical and Biological Sciences),78(7):173--178.
Kakinami Y S,Liu J Y,Tsai L C,Oyama K I.2010.Ionospheric electron content anomalies detected by a FORMOSAT-
3 /COSMIC empirical model before and after the Wenchuan Earthquake[J].International Journal of Remote Sensing,31(13):3571--3578.
Liu J Y.2009,Seismoionospheric GPS total electron content anomalies observed before the 12 May 2008 MW7.9 Wenchuan earthquake[J].J Geophys Res,114:A04320,doi:10.1029/2008JA013698.
Pulinets S A.2004.Ionospheric precursors of earthquakes:Recent advances in theory and practical applications[J].Terrestrial Atomospheric and Oceanic Sciences,15(3):413--436.
Xu W Y.2004.Decomposition of daily geomagnetic variations by using method of natural orthogonal component[J].J Geophys Res,109(A05218):229--239.
Yu T,Mao T,Wang Y G,Wang J S.2009.Study of the ionospheric anomaly before the Wenchuan earthquake[J].Chinese Science Bulletin,54(6):1080--1086.
Zhao B,Wan W.2005.Statistical characteristics of the total ion density in the topside ionosphere during the period1996—2004using empirical orthogonal function(EOF)analysis[J].Annales Geophysicae,23:3615--3631.
Zhao B,Wang M,Yu T,Wang W X,Lei J S,Liu L B,Ning B Q.2008.Is an unusual large enhancement of ionospheric electron density linked with the 2008great Wenchuan earthquake?[J].J Geophys Res,113:A11304,doi:10.1029/2008JA013613.
Zhou Y Y,Wu Y,Qiao X J,Zhu F Y,Yang J.2010.Anomalous variations of ionospheric VTEC before MS8.0 Wenchuan earthquake[J].Chinese J Geophys,53(3):556--566.
尼鲁帕尔·买买吐孙,张永仙.2012.地震电磁卫星电离层扰动研究进展综述[J].地震,32(1):105--117.
王武星,丁鉴海,余素荣,张永仙.2009.汶川MS8 .0地震前地磁短临异常与强震预测控索[J].地震学报,31(2):172--179.
袁运斌,欧吉坤.2002.基于GPS的电离层监测及延迟改正理论与方法的研究[J].科学通报,47(8):636--639.
章红平.2006.基于地基GPS的中国区域电离层监测与延迟改正研究[D].上海:中国科学院上海天文台:33--34.
祝芙英,吴云,林剑,周义炎,熊晶,杨剑.2009.汶川地震前电离层VTEC的异常响应[J].地震学报,31(2):180--187.
Chun C H,Liu J Y,Oyama K I,Yen N L,Liou Y A,Chen S S,Miau J J.2009.Seismo-ionospheric precursor of the2008 MW
7 .9Wenchuan earthquake observed by FORMOSAT-3/COSMIC[J].GPS Solutions,14:83--89.
Du A M,Huang Q H,Yang S F.2002.Epicenter location by abnormal ULF electromagnetic emissions[J].Geophys Res Lett,29(10):1455--1458.
Du A M,Tsurutani B T,Sun W.2008.Anomalous geomagnetic storm of 21—22January 2005:A storm main phase during northward IMFs[J].J Geophys Res,113:A10214,doi:10.1029/2008JA013284.
Du A M,Tsurutani B T,Sun W.2011.Solar wind energy input during prolonged,intense northward interplanetary magnetic fields:A new coupling function[J].J Geophys Res,116:A12215,doi:10.1029/2011JA016718.
Fenoglio M A,Johnston M J S,Byerlee J D.1995.Magnetic and electric fields associated with changes in high pore pressure in fault zones:Application to the Loma Prieta ULF emissions[J].J Geophys Res,100(B7):12951--12958.
Freund F T,Takeuchi A,Lau B W S,Post R,Keefner J,Melwn J,Al-Manaseer A.2004.Stress-induced changes in the electrical conductivity of igneous rocks and the generation of ground currents[J].Terrestrial Atomospheric and Oceanic Sciences,15(3):437--468.
Hayakawa M,Molchanov O A,NASDA/UEC team.2004.Summary report of NASDA’s earthquake remote sensing frontier project[J].Phys Chem Earth,29:617--625.
Huang Q.2002.One possible generation mechanism of co-seismic electric signals[J].Proceedings of the Japan Academy(B:Physical and Biological Sciences),78(7):173--178.
Kakinami Y S,Liu J Y,Tsai L C,Oyama K I.2010.Ionospheric electron content anomalies detected by a FORMOSAT-
3 /COSMIC empirical model before and after the Wenchuan Earthquake[J].International Journal of Remote Sensing,31(13):3571--3578.
Liu J Y.2009,Seismoionospheric GPS total electron content anomalies observed before the 12 May 2008 MW7.9 Wenchuan earthquake[J].J Geophys Res,114:A04320,doi:10.1029/2008JA013698.
Pulinets S A.2004.Ionospheric precursors of earthquakes:Recent advances in theory and practical applications[J].Terrestrial Atomospheric and Oceanic Sciences,15(3):413--436.
Xu W Y.2004.Decomposition of daily geomagnetic variations by using method of natural orthogonal component[J].J Geophys Res,109(A05218):229--239.
Yu T,Mao T,Wang Y G,Wang J S.2009.Study of the ionospheric anomaly before the Wenchuan earthquake[J].Chinese Science Bulletin,54(6):1080--1086.
Zhao B,Wan W.2005.Statistical characteristics of the total ion density in the topside ionosphere during the period1996—2004using empirical orthogonal function(EOF)analysis[J].Annales Geophysicae,23:3615--3631.
Zhao B,Wang M,Yu T,Wang W X,Lei J S,Liu L B,Ning B Q.2008.Is an unusual large enhancement of ionospheric electron density linked with the 2008great Wenchuan earthquake?[J].J Geophys Res,113:A11304,doi:10.1029/2008JA013613.
Zhou Y Y,Wu Y,Qiao X J,Zhu F Y,Yang J.2010.Anomalous variations of ionospheric VTEC before MS8.0 Wenchuan earthquake[J].Chinese J Geophys,53(3):556--566.
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