传播散射网络模型在电离层波传播研究中的应用
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摘要
用本征函数展开方法推广了传播散射网络模型,结合从地面以下到电离层中的水平分层模型,研究各向异性电离层背景中电磁波的传播问题。仿真结果显示:电磁波穿透电离层所需的最小频率为9.7 MHz;要在200 km高空获得DEMETER卫星电场探测器灵敏度以上的信号,所需要的偶极子源至少为7 kA.m,说明地震前期卫星探测到的VLF/ELF频段的异常信号不大可能直接由地下震源发出的。另一方面,震源偶力矩在正上方所产生的电场强度最大,所波及的范围在以震源为中心,半径为100 km的范围内,表明这种异常信号可能是震源产生的辐射场引起震源上方电离层底部的离子浓度等参数变化导致高能粒子放电或辐射所产生的。
Scattering network method is extended by using eigenfunction to study the propagation of electromagnetic wave in anisotropic ionosphere in this paper,combining the horizontal stratified model for the medium from underground to ionosphere.Simulation results show that the minimum frequency required for electromagnetic wave to penetrate through the ionosphere is 9.7 MHz,and a dipole intensity of at least 7 kA·m is needed for a signal to be detected by the electric probe on DEMETER satellite 200 km above the earth.The results indicate that the abnormal VLF/ELF signals detected by satellite before earthquakes are unlikely to be sent out directly by hypocenter of the earthquake.On the other side,dipole torque produces the most intensive electric field above the hypocenter,sweeping a circle region with radius of 100 km,which indicates that the abnormal signal may result from the lightening or radiation of high energy particles at the bottom of ionosphere.
Scattering network method is extended by using eigenfunction to study the propagation of electromagnetic wave in anisotropic ionosphere in this paper,combining the horizontal stratified model for the medium from underground to ionosphere.Simulation results show that the minimum frequency required for electromagnetic wave to penetrate through the ionosphere is 9.7 MHz,and a dipole intensity of at least 7 kA·m is needed for a signal to be detected by the electric probe on DEMETER satellite 200 km above the earth.The results indicate that the abnormal VLF/ELF signals detected by satellite before earthquakes are unlikely to be sent out directly by hypocenter of the earthquake.On the other side,dipole torque produces the most intensive electric field above the hypocenter,sweeping a circle region with radius of 100 km,which indicates that the abnormal signal may result from the lightening or radiation of high energy particles at the bottom of ionosphere.
引文
[1]MOLCHANOV O A,HAYAKAWA M,RAFAL-SKY V A.Penetration characteristics of electromag-netic emissions from an underground seismic sourceinto the at mosphere,ionosphere,and magnetosphere[J].J.Geophys.Res.,100(A2):1691-1712.
[2]NAGANOI,MAMBO M,HUTATSUISHI G.Nu-merical calculation of electromagnetic waves in an ani-sotropic multilayered medium[J].Radio Sci.,1975,10(6):611-617.
[3]XIA M Y,CHEN Z Y.Matrix-exponent formulationsfor wave radiation and propagationin anisotropic strat-ified ionosphere[J].IEEE Trans.Antennas andPropagation,2000,48(2):339-341.
[4]MIKHNEV V,VAINIKAINEN P V.Iterative step-like reconstruction of stratified dielectric media frommulti-frequency reflected field data[J].SubsurfaceSensing Technology and Application,2000,1(2):65-78.
[5]AZZAM R M,BASHARA N M.Ellipsometry andPolarized Light:North Holland[M].New York.1997.
[6]叶公节,刘兆汉.电离层波理论[M].北京:科学出版社,1983
[7]STRATTONJ A,Electromagnetic Theory[M].NewYork:McGraw-Hill,1941.
[8]戴振铎,鲁述.电磁理论中的并矢格林函数[M].武汉:武汉大学出版社,1995.
[9]MORGAN M A,FISHER D L.Electromagnetic scat-tering by stratified inhomogeneous anisotropic media[J].IEEE Trans.Antennas and Propagation,1987,35(2):191-197.
[10]熊年禄,唐存琛,李行健.电离层物理概论[M].武汉:武汉大学出版社,1999.
[11]OZAKI M,NAGANOI,YAGITANI S,et al.Iono-spheric propagation of ELF/VLF waves radiated fromearthquake[C]//Radio Science Conference 2004.Proceedings,2004 Asia-Pacific,2004:539-542.
[12]徐建华.层状媒质中的电磁场与电磁波[M].北京:石油工业出版社,1997.
[13]BILITZA D.International reference ionosphere2000[R].Radio Science,2001,36(2):261-275.
[14]PULINETS S,BOYARCHUK K.Ionospheric Pre-cursors of Earthquakes[M].New York:Springer,2004.
[2]NAGANOI,MAMBO M,HUTATSUISHI G.Nu-merical calculation of electromagnetic waves in an ani-sotropic multilayered medium[J].Radio Sci.,1975,10(6):611-617.
[3]XIA M Y,CHEN Z Y.Matrix-exponent formulationsfor wave radiation and propagationin anisotropic strat-ified ionosphere[J].IEEE Trans.Antennas andPropagation,2000,48(2):339-341.
[4]MIKHNEV V,VAINIKAINEN P V.Iterative step-like reconstruction of stratified dielectric media frommulti-frequency reflected field data[J].SubsurfaceSensing Technology and Application,2000,1(2):65-78.
[5]AZZAM R M,BASHARA N M.Ellipsometry andPolarized Light:North Holland[M].New York.1997.
[6]叶公节,刘兆汉.电离层波理论[M].北京:科学出版社,1983
[7]STRATTONJ A,Electromagnetic Theory[M].NewYork:McGraw-Hill,1941.
[8]戴振铎,鲁述.电磁理论中的并矢格林函数[M].武汉:武汉大学出版社,1995.
[9]MORGAN M A,FISHER D L.Electromagnetic scat-tering by stratified inhomogeneous anisotropic media[J].IEEE Trans.Antennas and Propagation,1987,35(2):191-197.
[10]熊年禄,唐存琛,李行健.电离层物理概论[M].武汉:武汉大学出版社,1999.
[11]OZAKI M,NAGANOI,YAGITANI S,et al.Iono-spheric propagation of ELF/VLF waves radiated fromearthquake[C]//Radio Science Conference 2004.Proceedings,2004 Asia-Pacific,2004:539-542.
[12]徐建华.层状媒质中的电磁场与电磁波[M].北京:石油工业出版社,1997.
[13]BILITZA D.International reference ionosphere2000[R].Radio Science,2001,36(2):261-275.
[14]PULINETS S,BOYARCHUK K.Ionospheric Pre-cursors of Earthquakes[M].New York:Springer,2004.
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