基于NWC甚低频信号的日出效应的观测与分析

doi:10.6038/cjg2020O0358

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摘要频率在3~30 kHz的甚低频（VLF，Very Low Frequency）波具有较小的传播损耗和较高的趋肤深度，可以在地球-低电离层波导中实现长距离传输，广泛应用于航海导航、对潜通信等领域，且在电离层遥测方面具有十分重要的意义.基于武汉大学自主研发的VLF接收机在武汉接收的NWC（North West Cape）台站信号，本文通过分析2018年4月23日—2020年7月22日的观测数据研究了日出期间NWC信号的幅度响应及其特点和规律.结果表明NWC信号日出期间的幅度响应主要包括两种极小值结构：2个幅度极小值（SR1、SR2）的Type I结构和3个幅度极小值（SR1、SR2、SR3）的Type II结构.在以SR1出现时间为时间零点进行时序叠加分析后发现，Type I结构比Type II具有更强的规律性和稳定性.在Type I结构下，SR2出现时间的波动范围、平均值、标准差分别为43~65 min、54.2 min、4.4 min，而在Type II结构下，SR2和SR3出现时间的波动范围分别为48~93 min、80~120 min，平均值分别为64.7 min、96.4 min，标准差分别为10.2 min、11.7 min.在27个月的观测期内，3—7月份Type I结构的出现概率100%，未出现Type II结构，而在1—2月和8—12月Type I结构出现的概率明显下降，最低降至1月份的20.7%，而Type II在1月、2月、11月的出现概率均高于70%.按春秋分交替变化（周期1和周期2）的统计结果，在周期1内Type I和Type II结构出现的概率分别为91.5%、8.5%，而在周期2内Type I结构出现的概率降至41.9%，Type II结构出现概率则升至58.1%，这表示观测期间内Type II结构主要出现在秋冬季，春夏季发生概率较低.

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	王市委
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	陈欢
	李光剑
	倪彬彬
	赵正予
	袁丁

关键词 ： NWC甚低频信号, 日出效应, 幅度响应, 观测与分析

Abstract：Very-low-frequency (VLF) waves at frequencies of 3~30 kHz can propagate within the Earth-ionosphere waveguide over a long distance due to the small propagation loss and high skin depth. VLF signals are widely used in various fields including navigation, submarine communication and ionospheric remote sounding. In this paper, the self-developed Wuhan University VLF receiver system is adopted to detect the NWC (North West Cape, Australia) VLF transmitter signals (19.8 kHz) at Wuhan, Hubei propagating over a long vertical path >6000 kilometers. By analyzing the ground-based NWC signal data obtained during the period from April 23, 2018 to July 22, 2020, the sunrise effect on the amplitude variation of the NWC VLF signals is investigated in detail. The amplitude responses are categorized to include Type I with two amplitude minima (SR1 and SR2) and Type II with three amplitude minima (SR1, SR2 and SR3). By performing the superposed epoch analysis with the SR1 occurrence time as the zero epoch time, we find that Type I is more stable than Type II. For Type I, the SR2 occurrence time varies between 43~65 minutes, with the mean value and standard deviation of 54.2 minutes and of 4.4 minutes, respectively. In contrast, for the Type II events, the variation range, mean value and standard deviation are 48~93 minutes, 64.7 minutes and 10.2 minutes, and 80~120 minutes, 96.4 minutes and 11.7 minutes for SR2 and SR3, respectively. During the 27-month period, the occurrence rate is 100% for Type I and zero for Type II during the seasonal interval from March to July. The Type I occurrence reduces significantly in other months with the minimum of 20.7% in January. The occurrence probability of Type II is >70% in January, February, and November. The statistical results within the period of equinox-solstice (Period 1 and Period 2) indicate that Type I (Type II) occurs with the probability of 91.5% (8.5%) in Period 1, and in Period 2 the occurrence probability of Type II (Type I) increases (decreases) to 58.1% (41.9%). Consequently, the Type II amplitude variation of NWC VLF transmitter signals frequently occurs in autumn and winter, and occurs in summer and spring with a much lower probability.

Key words： NWC VLF signals Sunrise effect Amplitude responses Observation and analysis

收稿日期: 2020-09-17

PACS:

P352

基金资助:国家自然科学基金（42025404，41574160，41674163），中国航天局预研项目（D020303，D020308），澳门科技大学月球与行星科学实验室和中国科学院月球与深空探测重点实验室伙伴实验室开放课题的支持，以及深圳市科技创新委员会自由探索项目的（JCYJ20180306172239618）资助.

通讯作者: 顾旭东,男,副教授,主要从事磁层物理和低频波观测系统及传播等方面的研究.E-mail:guxudong@whu.edu.cn E-mail: guxudong@whu.edu.cn

作者简介: 王市委,男,博士生,主要从事甚低频接收机的设计、信号与数据处理等方面的研究.E-mail:wangsw@whu.edu.cn

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http://www.geophy.cn//CN/10.6038/cjg2020O0358 或 http://www.geophy.cn//CN/Y2020/V63/I12/4300

Chakrabarti S K, Sasmal S, Chakraborty S, et al. 2018. Modeling D-Region Ionospheric Response of the Great American TSE of August 21, 2017 from VLF signal perturbation. Advances in Space Research, 62(3):651-661.
Chand A E, Kumar S. 2016. VLF modal interference distance for a west-east propagation path to Fiji.//2016 URSI Asia-Pacific Radio Science Conference (URSI AP-RASC). Seoul, South Korea:IEEE, 1306-1309, doi:10.1109/URSIAP-RASC.2016.7601184.
Chand A E, Kumar S. 2017. VLF modal interference distance and nighttime D region VLF reflection height for west-east and east-west propagation paths to Fiji. Radio Science, 52(8):1004-1015.
Chen Y P, Ni B B, Gu X D, et al. 2017. First observations of low latitude whistlers using WHU ELF/VLF receiver system. Science China Technological Sciences, 60(1):166-174.
Chen Y P, Yang G B, Ni B B, et al. 2016. Development of ground-based ELF/VLF receiver system in Wuhan and its first results. Advances in Space Research, 57(9):1871-1880.
Chen, L, Gu, X D, Cheng W, et al. 2020. Monitoring of atmospheric noise based upon data obtained by WHU VLF detection system. Spacecraft Environment Engineering, 37(2):107-114, doi:10.12126/see.2020.02.001.
Clilverd M A, Duthie R, Rodger C J, et al. 2017. Long-term climate change in the D-region. Scientific Reports, 7:16683.
Clilverd M A, Thomson N R, Rodger C J. 1999. Sunrise effects on VLF signals propagating over a long north-south path. Radio Science, 34(4):939-948.
Crombie D D. 1964. Periodic fading of VLF signals received over long paths during sunrise and sunset. Journal of Research of the National Bureau of Standards Section D Radio Science, 68D(1):27-34.
Golden D I, Spasojevic M, Inan U S. 2009. Diurnal dependence of ELF/VLF hiss and its relation to chorus at L=2.4. Journal of Geophysical Research:Space Physics, 114(A5):A05212, doi:10.1029/2008JA013946.
Hua M, Li W, Ni B B. et al. 2020. Very-low-frequency transmitters bifurcate energetic electron belt in near-earth space. Nature Communications, 11, 4847. https://doi.org/10.1038/s41467-020-18545-y.
Korsakov A A, Kozlov V I, Toropov A A. 2020. Seasonal variations of the amplitude of the VLF radio signals and the intensity of the atmospheric electric field in cryolithozone conditions.//IOP Conference Series:Materials Science and Engineering. Russky Island, Russian Federation:IOP Publishing, 753(4):042093, doi:10.1088/1757-899X/753/4/042093.
Kumar A, Kumar S. 2018. Solar flare effects on D-region ionosphere using VLF measurements during low-and high-solar activity phases of solar cycle 24. Earth, Planets and Space, 70:29.
Liu, X, M.1987. Radio Wave Propagation. Beijing:Higher Education Press.
Lynn K J W. 1967. Anomalous sunrise effects observed on a long transequatorial VLF propagation path. Radio Science, 2(6):521-530.
Ma, X, Xiang, Z, Ni, B, et al. 2020. On the loss mechanisms of radiation belt electron dropouts during the 12 September 2014 geomagnetic storm. Earth and Planetary Physics, 4(6):598-610.
Maurya A K, Phanikumar D V, Singh R, et al. 2014. Low-mid latitude D region ionospheric perturbations associated with 22 July 2009 Total Solar Eclipse:Wave-like signatures inferred from VLF observations. Journal of Geophysical Research:Atmospheres, 119(10):8512-8523.
Muraoka Y. 1982. A new approach to mode conversion effects observed in a mid-latitude VLF transmission. Journal of Atmospheric and Terrestrial Physics, 44(10):855-862.
Ni B B, Bortnik J, Thorne R M, et al. 2013. Resonant scattering and resultant pitch angle evolution of relativistic electrons by plasmaspheric hiss. Journal of Geophysical Research:Space Physics, 118(12):7740-7751.
Ni B B, Huang H, Zhang W X, et al. 2019. Parametric sensitivity of the formation of reversed electron energy spectrum caused by plasmaspheric hiss. Geophysical Research Letters, 46(8):4134-4143.
Ni B B, Thorne R M, Shprits Y Y, et al. 2008. Resonant scattering of plasma sheet electrons by whistler-mode chorus:Contribution to diffuse auroral precipitation. Geophysical Research Letters, 35(11):L11106, doi:10.1029/2008GL034032.
Pappert R A, Snyder F P. 1972. Some results of a mode-conversion program for VLF. Radio Science, 7(10):913-923.
Parrot M, Berthelier J J, Lebreton J P, et al. 2008. DEMETER observations of EM emissions related to thunderstorms. Space Science Reviews, 137(1-4):511-519.
Ries G. 1967. Results concerning the sunrise effect of VLF signals propagated over long paths. Radio Science, 2(6):531-538.
Samanes J E, Raulin J P, Macotela E L, et al. 2015. Estimating the VLF modal interference distance using the South America VLF Network (SAVNET). Radio Science, 50(2):122-129.
Samanes J, Raulin J P. 2011. Characteristics of nighttime West-to-East VLF waves propagation using the South America VLF Network (SAVNET).//2011 SBMO/IEEE MTT-S International Microwave and Optoelectronics Conference. Natal, Brazil:IEEE.
Steele F K, Crombie D D. 1967. Frequency dependence of VLF fading at sunrise. Radio Science, 2(6):547-549.
Šulić D M, Srećković V A, Mihajlov A A. 2016. A study of VLF signals variations associated with the changes of ionization level in the D-region in consequence of solar conditions. Advances in Space Research, 57(4):1029-1043.
Thompson A M, Archer R W, Harvey I K. 1963. Some observations on VLF standard frequency transmissions as received at Sydney, N. S. W. Proceedings of the IEEE, 51(11):1487-1493.
Wait J R. 1968. Mode conversion and refraction effects in the Earth-ionosphere waveguide for VLF radio waves. Journal of Geophysical Research, 73(11):3537-3548.
Walker D. 1965. Phase steps and amplitude fading of VLF signals at dawn and dusk. Journal of Research of the National Bureau of Standards Section D Radio Science, 69D (11):1435-1443.
Yamaguchi H, Hayakawa M. 2015. Very exceptional cases of VLF/LF ionospheric perturbations for deep oceanic earthquakes offshore the Japan island. Journal of Asian Earth Sciences, 114:279-288.
Yi J, Gu X D, Cheng W, et al. 2020. A detailed investigation oflow latitude tweek atmospherics observed by the WHU ELF/VLF receiver:2. Occurrence features and associated ionospheric parameters. Earth and Planetary Physics, 4(3):238-245.
Yi J, Gu X D, Li Z P, et al. 2019.Modeling and analysis of NWC signal propagation amplitude based on LWPC and IRI models. Chinese Journal of Geophysics (in Chinese),62(9):3223-3234, doi:10.6038/cjg2019N0190.
Yoshida M, Yamauchi T, Horie T, et al. 2008. On the generation mechanism of terminator times in subionospheric VLF/LF propagation and its possible application to seismogenic effects. Natural Hazards and Earth System Sciences, 8(1):129-134.
Zhima Z, Cao J B, Liu W L, et al. 2014. Storm time evolution of ELF/VLF waves observed by DEMETER satellite. Journal of Geophysical Research:Space Physics, 119(4):2612-2622.
Zhou R X, Gu X D, Yang K X, et al. 2020. A detailed investigation of low latitude tweek atmospherics observed by the WHU ELF/VLF receiver:I. Automatic detection and analysis method. Earth and Planetary Physics, 4(2):120-130.
Альперт Я Л.1981. Radio wave propagation and ionosphere. Yuan, Y. Beijing:Posts and Telecom Press.
附中文参考文献
阿尔别尔特. 1981. 无线电波传播和电离层. 袁翊译. 北京:人民邮电出版社.
陈隆,顾旭东,程雯等. 2020. 基于WHU甚低频探测系统的大气噪声监测. 航天器环境工程, 37(2):107-114, doi:10.12126/see.2020.02.001.
刘选谋. 1987. 无线电波传播. 北京:高等教育出版社.
易娟,顾旭东,李志鹏等. 2019. 基于LWPC和IRI模型的NWC台站信号传播幅度建模分析. 地球物理学报, 62(9):3223-3234, doi:10.6038/cjg2019N0190.