不同方位甚低频电磁波衰减的初步研究*

Abstract

Abstract: Based on power spectral density data of electric field at 19.8kHz recorded by the DEMETER satellite during 2005—2010from NWC transmitter in Australia,the spatial distribution of the electric field at topside ionosphere and its magnetic conjugate region excited by NWC and its attenuation features at different directions by using statistical analysis and linear fitting methods are studied.The results show that,(1)at the topside ionosphere above NWC,the electric field recorded by satellite exhibits elliptical dispersion,and the position of maximal electric field center drifts to north and east relative to NWC;(2)the attenuation gradient in northern direction studied region is the smallest in four directions,and the east one is the largest;(3)at magnetic conjugate region,the attenuation gradient at south direction is the smallest,but the north one is the highest. The comprehensive analysis illustrates that,when the VLF electromagnetic wave from NWC transmitter penetrates into ionosphere,it will be controlled by geomagnetic field and mainly propagates along the magnetic power line,so the maximal center of electric field will drift to magnetic equator,and the attenuation gradient at equator-ward direction will be the smallest.

Key words: VLF electric field, NWC transmitter, Attenuation coefficient, DEMETER satellite

CLC Number:

P315.7

XU Wei-Dong, ZHANG Xue-min, LI Zhong, ZHAO Shu-fan, WANG He-sheng. Relationship between Very Low Frequency Electromagnetic Wave Attenuation and Directions[J]. EARTHQUAKE, 2016, 36(2): 60-67.

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Relationship between Very Low Frequency Electromagnetic Wave Attenuation and Directions

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